Happy to help man! Really appreciate the shoutout. 🔥 This is such a cool project and I can’t wait to see where this goes! My unique build also went through some growing pains but every time out was a learning opportunity and now we’re at 185MPH! Keep going and always happy to help 🏎
wooo! I made it into the vid!! thanks for the mention! was a pleasure to meet you. a few of us were using gyros, we have the futaba one. if it wobbles you can turn down the gain, but it looks like it might be picking up vibrations. i find the 3m double sided grey vba tape the best. cheers!
Doh! 😖 wish I the car survived to get another run so I could have tried that trick with the tape and turned down the gains! The pleasure was all mine, man! Hope to see you at another event! 👍
That gyro would have been massively freaked out by the vibration. On RC helis, the gyros (flybarless units) are installed on an anti-vibration pad to help alleviate the effects, but the vibrations from rotary flight look like nothing compared the vibes you would get from running on rough tarmac. Looking at that, I'm not surprised the other guys didn't use gyros.
Yea, at those speeds the vibrations must be making the gyro think it has gone off center and then it tries to correct the movement that it's causing itself. The only way to fix that would be to record data from accelerometers and create gyro software with the right compensations.
Having a longer smoothing interval on the raw gyro data might help a lot with reducing vibration-induced oscillations. Only downside is the gyro becomes less responsive to sudden jerks, but I think for a speed car this wouldn't matter too much, since being smooth on the steering should help with stability at speed.
Raz Shifrin has used gyros on every one of his cars and he's one of the fastest in the speed running scene. To be fair, he uses Futaba gyros which are the best in the game (at least for cars anyways but I think they do alright in the flight world as well if I'm not totally mistaken). He has it turned waaaay down so as to not cause violent oscillations which only get worse the faster you go. Now, I know he said no one else there was using them so I don't want to rule out the possibility that Raz decided to change his setup based on the conditions on the ground but, at the same time, I'd be more than a little surprised if he did. As the old adage goes, don't fix what ain't broken. I could be wrong of course. This is just my initial take after having watched Raz for a few years and his approach to the use of available technologies in his vehicles.
@@JJayzX Believe in JESUS today, confess and repent of your sins. No one goes to heaven for doing good but by believing in JESUS who died for our sins. For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.(John 3:16)🥳❤️😁❤️
RC car speedrun community seems like a fun bunch… thanks for putting them in the spotlight!! You’re probably right about the slop in steering causing your oscillations. Might be worth adding some stabilized rudder surfaces and leave the main steering unstabilized
@@bob2859 Believe in JESUS today, confess and repent of your sins. No one goes to heaven for doing good but by believing in JESUS who died for our sins. For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.(John 3:16)🥳❤️😁❤️
I LOVE how you always showcase your “mistakes,” and reframe them as learning experiences; especially with your infectious positive attitude about how much you’ve learned. This is such a great example to show my young niece and nephew; well actually for anyone for that matter! Thanks for sharing this fascinating video with us!!!
Believe in JESUS today, confess and repent of your sins. No one goes to heaven for doing good but by believing in JESUS who died for our sins. For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.(John 3:16)🥳❤️😁❤️
My first thought was the servo. For those kind of speeds you probably want something heavy duty and pretty rigid, that may be part of what caused the gyro to get confused.
That’s possible but I’m sure the oscillation is initiated by the input noise from the road. Without any sort of tuning there’s absolutely no way that the gyro will be able to work properly on a bumpy tarmac at 100 mph even if the servo was a good match. People will spend dozens of hours of testing to tune a gyro for a purpose like this because of the extreme conditions.
@@Chevsilverado yes I agree my stream liner uses 2 gyros one 3 channel for the aero and a gy401 for steering, shock absorbing mounts are critical but if too soft the problem will come back just like a slow servo,I e had some bad crashes tuning gyros in and even planes it’s not much different if u have snapped a prop mid air it usually doesn’t end well lol also just as critical to the gyro as servo speed is it’s location on the chassis it greatly effects its response! Having said that most of my speed runs are on very bumpy outback Australian roads so my cars are usually tuned on rough surfaces my best pass was only 218kmh but was done on rough loose surface roads and only managed a bit over a full second of full throttle but it’s better than the xo1 on same surface only could do 150kmh before taking flight
One of the best series yet! Edit: I would love to see a mini Bloodhound build with the jet engine, as this would be realistic to the actual Bloodhound. (Because you mentioned redesigning the chassis to incorporate the engine)
Gyro in a car will reach an oscillation speed due to the servo max slew speed. You can reduce the problem by mounting the gyro on the upright so it turns with servo (or doesn’t turn with the car in a slide. What you need to do is use a flight controller like ardurover to have gps pid position control for the whole length of the runway and onboard data logging.
I second the flight controller idea. A flight controller would allow a lot more adjustment. I'd also add pitot air speed indicator and a quadrature encoder on at least one wheel to be better speed data. Edit: The flight controller should have either a flash chip or a SD card for black box data. Lots of great information can be logged using programs like ArduRover.
Believe in JESUS today, confess and repent of your sins. No one goes to heaven for doing good but by believing in JESUS who died for our sins. For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.(John 3:16)🥳❤️😁❤️
@@alunesh12345 Stop making Christians look like crazy people. Are you really Muslim trying to make Christians look bad? Whatever you believe, stop spamming. It's EVIL.
The issue with the gyro is that the steering sensitivity increases with speed. Meaning at low speeds the gyro gain is correct but at higher speeds the total output gain (steering + gyro gain) has increased causing the oscillations. I would not recommend a simple gyro for this. Maybe a flight controller with GPS to dynamically change the gain correctly for the speed?
I agree, gyro's require tuning, and you are operating it in 2 distinct scenarios, so you either need to tune it for high speed, or both, def not ONLY tuned for low speed (the way you have it now). The front suspension could be replaced and/or upgraded... I don't think the platform is stable enough for high speed passes without one, or both. I would also like to see some larger/stiffer/lighter gussets on your wing, it appears to be VERY helpful.
Quad flight controllers used to have all sorts of problems with vibrations inducing signals into the gyros. It was solved with speeding up the sampling and pid-loop and with advanced filters. I doubt that gyro has what it takes.
@@ulwur Back in the day, before advance filtering, PID controllers had TPA, which essentially softened the gain as throttle increases. I think for simple controllers (such as this car in the video) could probably work by using a programmable gyro. There are some RC car gyros that can be tuned via RC link, which allows you to mix the throttle channel with the gain.
@@kwaaaa That seems ideal. I got into building quads 6ish years ago, and I have only heard of someone using throttle P.I.D. attenuation once... it doesn't seem to be necessary on drones. This car, however, seems like an ideal candidate.
I guess some pesky rules might forbid the use of autonomous steering using mmWave/microwave beacons aimed along the track in a sort of nanoscale ILS guidance system? Do you have datalogging on the servo and gyro? Is there any sign of the gyro outputs maxing out? Can you map the gyro gain and PID control loop parameters to vary with speed? How about using explosafe cellular filler inside the tank to reduce sloshing? Compliant/damped mountings to reduce high-frequency vibration noise from the track surface? Kalman filters to manage measurement noise? Viscous damping and maybe spring preload of the steering mechanism to take out any backlash at the neutral position of the servo? Looks like a huge amount of fun to be had. Great seeing the evolution of this project.
Great video as always. I really like you reflecting on changes, looking for errors and being able to find them, even when they're your own. When going on with this project, I would strongly suggest looking into landspeed record cars and their setup. All of them are low-drag, low-downforce configurations. Especially with no wheels being driven, a rear wing makes not much sense for downforce, however the vertical stabilizer is often used in LSR cars. The rear wing will effectively lever up your front wheels, making the car instable at speed. A front wing to counter this or even a unified "central" wing (think aircraft aerofoil upside down) might make sense, with a small vertical stabilizer at the rear. As I said, enjoy your content and the experimenting you are doing. Have fun!
Two suggestions: ditch the spektrum radio and go for something more modern like Crossfire or ELRS. If you want to use some active stabilization, go for something that provides you with logs so you can analyze the behavior dynamically.
After watching a few times just something I'd like to add. Thrust angle from the jet is quite important. Jet cars for drag racing and landspeed actually slightly angle the jet downwards. Which seems counter intuitive but that's where your downforce comes in the trick here is balancing your downforce and thrust angle.
Failed in creating a 100mph car but succeeded in gaining valuable information on how to get to a 100mph car SAFELY and RELIABLY. Not to mention tips and contacts from the event who have the same pursuit. That's a win for any engineer and glad you think the same way!
I'd invest more into the suspension. An inwards toe angle makes the car want to go in a straight line, where an outwards toe angle makes the steering more responsible but the whole car way more unstable. Positive caster also helps with stability. Camber can be used to reduce the patch area.
Believe in JESUS today, confess and repent of your sins. No one goes to heaven for doing good but by believing in JESUS who died for our sins. For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.(John 3:16)🥳❤️😁❤️
@@alunesh12345 Barakaka Allah feek. Now while the sons of Israel were in the wilderness, they found a man gathering wood on the sabbath day. Those who found him gathering wood brought him to Moses and Aaron and to all the congregation; and they put him in custody because it had not been declared what should be done to him.read more. Then the Lord said to Moses, “The man shall surely be put to death; all the congregation shall stone him with stones outside the camp.” So all the congregation brought him outside the camp and stoned him to death with stones, just as the Lord had commanded Moses. Numbers 15:32-36
Damn man, I'm 36 years old and have had an engineering mindset my entire life despite not going to school for it. To see someone your age making a jet powered RC car, then crashing, and having such a positive attitude about it, fills me with a lot of confidence about future generations. Keep developing your passion, by the time your my age your GOING to engineer something truly epic, and I can't wait to see it. Subscribed!
Your experiment did NOT FAIL at all. What it did was teach you a lesson and how to overcome it. I say that's a win win. I can't wait to see the new car!! You got this!!!
Two things need attention immediately before you move forward. 1st. Spectrum radios are prone to interference from high power wifi telemetry. We proved this at Flite Fest when people fly near the pump out in the field. When it pulses its data (and this is not bias for radio types) spectrum radios tend to fail safe if within the direct path of that pulse. I assume an airport uses similar devices for various things they need to track. Look into that or swap radios or receivers for better. Second: Gyros are SUPER sensitive. Vibrations will drive them bonkers specially if it hits a resonant frequency. IF you intend to use one then you need to look into some kind of soft mounting to isolate the gyro from any part of the body. Bumps and bouncing usually won't effect them to much if the gain is set properly. A resonance however will totally bork the system and may as you saw induce a drift or totally lock what ever it is controlling. (This is actually what I think happened on this particular run but the radio stuff needs to be checked in any and all cases)
Spektrum radios are great but have some of the shortest ranges of radio systems I have used. For this job maybe you could look at some other radio systems used for long range drone flying or something like that. Kevin uses the "Dumbo" RC radio, it might be better for this type of project.
Really interesting attempts and development iterations. Being into liquid rocket hobbies my first glance at your construction made me wonder why you haven't slush plates in your fuel tank? The fuel might start oscillation wildly at an unpredictable speed because of this. Might just be one of several reasons in combination. It would be easy to eliminate this, just by filing the tank half way up with a few large metal spiral chips from a lathe or from drilling.
Just rebuild the steering with all metal, high precision parts so it has no slop. Put rudders on the fins and have the gyros operate those instead of the steering. Experiment with speed dependent actuation %. The faster it goes, the less correction to prevent applying so much steering input it makes the car turn too much. Another thing to look into is detecting oscillation caused by the gyro. In that case it should return the rudders to neutral and hold them until wobble stops. If two rudder servos are used, they could be both turned to maximum outwards to act as air brakes. One more thing, mount the engine with a little bit of upward tilt at the rear to push the rear end down. Having it parallel to the chassis is going to make it rock forward, putting more force on the front wheels. That will put more drag on the front, less on the rear, leading to amplifying the effects of steering and wanting to spin around - resisted only by the big fins.
Need to mount the jet very low and as far forward as you dare - Use some duct work for intake and exhaust. You could use a venturi effect for the jet thrust to create some downforce by sucking some air out from under the car. If the centre of drag/lift is behind the centre of mass it shouldn't go out of control so badly, and at speed it will become even more stable.
Was looking for a comment like this. The amount of thrust is just too much for a car that light, it completely dominates any aero the car has. Pulling the car forward with a front mounted engine seems like an obvious (and not particularly pleasing to look at) solution.
I think making a custom purpose built car is the way to go. Incorporate the engine into the chassis and really stiffen it up. Make some suspension components where you can control the wheel geometry (adding a bit of caster into the front steering wheels will help greatly at high speed). Beef up the steering servo as well for rigidity and crash resistance. Even make a new new body shell out of fibreglass or carbon fibre to cover the chassis and engine as one piece. Don't really need to worry about too much weight as you're after top speed instead of top acceleration (though heaps of weight would make steering difficult). Fantastic vid as always 🙂
Here's some suggestions which hopefully may help before it's next run. Cut out the body around the engine so you can lift it on and off easily. Turn down the steering 'dual rate' on the transmitter to about 60%, it'll make it less 'twitchy'. If you run the gyro make sure the gain isn't too high, you only want the gyro to assist, not totally control. Add a separate failsafe or kill switch for the engine so you can kill it remotely if possible using an aux channel. Swap the receiver out for an aeroplane receiver as it will give you more range. Hope that helps :)
You could add an fpv camera to get a drivers pov, instead of turning around everytime the car passes and hoping you go off track (plus the help of the gyro). You can also go even further than you used to because you can see everything in front of you. The only problem being cost.
Great series! I think it would be really useful if you installed some fpv gear on the car so you could more easily steer it and get oscillations under control faster
Speedrunning RC's is no joke... gyro's are amazing tech if set up properly. another trick we speedrunners use is turning down the dual rate of your controller so any steering inputs are dulled out a bit more. (you can also do this with negative exponential values). Dont get your head down. I got out of the game after a nasty crash that totalled my ride but the thrill of watching your build go by can't be beat. Good luck out there!
You've demonstrated one law that affects many hobbies. Others in the hobby will be quick to tell you what you're doing wrong, with little, to no evidence to back it up. Following their advice blindly would have seet you back. Every hobby has these people.
I’m not an engineer but here’s my unsolicited $.02 anyways. It would add some drag but I would recommend pointing the front of those massive fins inwards so if the tail goes to the right the left fin will be more streamlined and the right side will cause more drag pushing the tail back to the left. In a weird way this would act like dihedral in a wing and be positively stable both statically and dynamically. Also ditch the gyro though I would have tried it too just like you. Great vid BTW
I have a theory. If you are pushing it with thrust from the rear of the car it's less stable. My theory is that you move the engine to the front and give it just the right angle to keep it slightly pushing down similar to the current setup but slightly more and sorta have the chassis be following along. This would increase the downforce and imo increase stability. The large upright wings would still be needed. Very neat project you have. Lots of luck to you
@7:00 yes - that is exactly what I was thinking you need. If you can get that engine down low into the body it will be a game changer. Take a look at how a jet dragster or top fuel dragster is set up to go 300+ miles an hour in a quarter mile.
Amazing work. I would add dividers in the fuel tank to stop the fuel sloshing around, and lower the engine as much as possible by cutting out some of the moulded shell and 3D printing a aero housing.
Great work and I like the attitude never rely on what some one thinks they saw there is a reason they cover new rockets in engineering cameras. Good luck with the new build.
Maybe u should place d engine as low as possible and then use an s duct to feed it air Plus the oscillation might just b caused by the car wanting to take off, u might want to work on generating more downforce Looking forward to more projects 😃😃😃
gyro's are programed to work at acceleration around g (10 m/s), it gives different outputs at higher accelerations. you can use accelerometer for correcting gyro's output.
I don't think this is correct. Accelerometers are used to correct a gyro's sense of "up" in a flight controller. Gyros drift over time but the type used in the video don't need this sort of correction since it's only tracking a single axis of rotation.
As soon as I saw you were at Rossa I knew Kevin Talbot might appear in it somewhere. Also heard Raz Shifrin giving some design pointers as he makes some insane speed cars. Now I just have to wait to see their videos of the event and Kev showing us your car in his video.
Gyro gain and non isolated plus steering slop. Bin it off the steering and add it to the vertical stabilisers with rudders. Also use a quad flight controller with inactive so you can data log. They are cheap enough and you can use car or boat profiles. Also, spectrum and loss of signal, who’d of thought it.
The reason for some of the issues is due to your braking i believe, if i remember correctly you are braking with the back wheels. Full-size cars brake predominantly on the front wheels for a reason. When you are braking with the back wheels you are essentially moving the center of stability forwards, past the center of gravity. You see this effect when you are driving on ice and use the handbrake. rotating wheels have higher lateral grip than spinning/sliding wheels. The wing helps to counteract this, keeping the center of stability behind the center of mass until you lose enough speed, at which point you lose control. This might also be why it stopped wobbling when the motor gave full gas again, just to crash. A relevant example with wheels and grip that may be worth mentioning, when you are braking and accelerating you are essentially borrowing lateral grip. When a FWD car accelerates too hard in a corner they crash front first When a RWD car accelerates too hard in a corner they crash ass first. the same holds true with front brake vs handbrake. The fact that the center of thrust is above the wheels is probably also adding to this, by putting more pressure on the front wheels during acceleration. Cars which use a normal motor which spins the wheels have a center of thrust that is both at ground level, and is in the same direction as the ground itself.
Sorry to write this, but you are wrong. You can have a blown up tire on the front wheels of your car and control it safely to the stand. But a blown up tire on the rear wheels will spin you out of control. The back wheels is what is stabilizing your motion. The front wheels are for steering the car. The same goes for braking. If you brake only on the front, you move the braking point in front of the center of mass, making the car instable. If you brake on the rear, you move the braking point behind the center of mass. The pitch of the car towards the front while braking (forced by the suspension) moves the center of mass also to the front and makes it necessary to have bigger brakes on the front than on the back.
@@Craftlngo Part of that is exactly what i'm describing. The back wheels is what stabilizes the motion, when you brake to the point where the wheels start to slide you lose lateral traction. This is why braking only on the rear wheels causes you to lose control. Braking to the point of sliding is analoguos to the tire blowing up, just to a smaller amount. Braking the back wheels to the point of sliding moves the center of stability forwards by an immense amount. This is what i described at the end with the braking on ice. I am sorry if that was unclear. Something i also have to say is that the center of mass is always the same, What changes when you brake is not the center of mass, but the direction of "acceleration". All things experience 9.8 m/s/s, ie a 1-60 accelaration of about 3 seconds constantly, That is gravity. When you brake you add an additional force - deacceleration. That force if it equals 1g(9.8 m/s/s) moves the direction of acceleration 45°, putting the center of pressure on the wheels forwards, which makes the traction act as if the center of mass is moved forwards.
Awesome project. When attending meets like that, there will always be the "I know better" kind of people, especially when you're new in the group. Some are worth listening too. Others just love the sound of their own voice. You did a good job verifying the issues with the design. Since it's experimental on many levels, there are no real rules how to go about it. You can't be first while following someone else's footsteps. To throw my hat in the ring, I'd consider having a separate channel for the gyro and actually give the stabilizing fins air rudders and a lightning fast servo. It's only at high speeds you need the assistance, and by then the rudders should give adequate correction force while allowing for a quicker response since the servo won't have to fight against the centrifugal forces of the spinning wheels. Cheers!
Hi, I think I have a really easy improvement with large benefit: The oscillation is dramatically worsened by your fuel tank. Look at a tanker for example. They have ridges inside of the tank to stop the fuel from flapping arround too much
Sorry for the late comment. Enjoying watching this jet car go. I caught it at the end of the video. Loss of signal and the fail-safe problem. That problem starts with the DX6e. The e models don't have the diversity antenna system. The single antenna has good range to the sides of the transmitter, but if you point the antenna towards your car, plane, whatever, you are effectivity putting it in the cone of silence. I happen to like and use Spektrum for flying. Just not the e model transmitters. I've seen planes lost because of antenna being pointed towards the bird at half the distances I fly out to with only a dozen dropped frames on my DX18. I'd bury that 6e in a shallow grave at midnight and upgrade to a full DX6, 8 or better before attempting another speed run. Good luck and keep the vids coming.
Piece of advice, don't take aerodynamics advice from people who are not experts. Trust your own testing and then make any Nessasary changes. Good luck.
14:45 You say that the wheel wobble didn't happen without the gyro, but it clearly was. It looks like the gyro is trying to compensate for that slight wobble, but with the slop in the system and possibly some resonance from the fins it can't get there. I would look at rebuilding the front end then tuning the gains on the gyro.
It would be great if you could funnel the flow of that venturi from the jet exhaust entering the tube through slots in the base frame to get ground suction like some of the fan suction race cars of the past
Someday I'd like to see a hobbyist build a simple laser guiding system that you could just place at the end of the track so the car would home automatically to it. Steering a high speed RC car is just a recipe for disaster. The gyro is a good idea though!
I agree with you,the gyro was to sensitive,any play in your steering will exaggerate the gyro compensation,I would run without gyro and a small degree of tow out on the front,this should help to keep it running straight,hope you have mire success on the next run I watch in anticipation 👍
You're bringing the heat at the event up, and I can totally see how you could have made that error with the radio. Heat is no joke - I've had heatstroke exactly once, while I was a camp counselor, and I never want to experience that again. Stay hydrated, homies! Seriously, though, hot weather can be a killer, especially if you're not used to it.
200mph+ on electric rc car already achieved ... interresting project but so far from improving that record, was thinking like non rc world where jet powered are unbeatable ! How fast theoricaly can push those rc jet ? Keep it up ;).
A couple more tips for improving handling,heavier silicone oil or smaller valves in the shock’s and more spring rate on the rear will do more than fuel line,also you need Less front traction! You want to go straight so put grip on the back and as much as you can! and a set of Harder compound tyres on the front, if using foam you can shape the front tyre’s so it acts like extreme negative camber ie not cylindrical but conical profile the added benefit is the narrow point of tyre touching the road is easier to compress and will absorb more bumps and more aerodynamic! Hope this helps!
100% the Gyro gain causing that 'oscillation'. I'm not sure how much you can turn it down on them ones. If you are going to continue to use one, have a look at the Onisiki 3 Axis one. Super precise and easily adjustable gain from your Tx. Look forward to seeing this hit triple figures. (Edit: watched till the end...yes, agree, slop and gyro) :)
I love how the Genius's in the trade are so supportive and un-biased towards further ingenuity. What a great Hobby... If only Government could be as transparent as this with their invisible budget to explore exotic tech
I’m not an engineer, so I’m sorry if I’m dumb for even suggesting this, but if you wanted the covered wheels with it having no chance of it rubbing against… maybe try putting two runners (would be part of the frame) along either side of the vehicle, similar to modern go-karts, attach the cover on top of that? Just a thought, might have other unforeseen consequences though. Either way, love this! First jet-powered RC I’ve ever seen. And it’s beautiful
14:45 you can see the wheels slightly expand from the wheels spinning so fast which I think is pretty cool as is. I would so love the opportunity to mess around with a jet turbine though
I don't think it's a good idea to disagree with the designer of the best limitless wing on the market. His cars don't oscillate at over 190 mph with much stronger cross winds. The gyro wouldn't have been overcompensating if there hadn't been an oscillation in the first place. You made a giant sail behind the rear axle.
good job... suggestion tho.. i would brace the wings to the frame via supports to the frame at the top (in last testing you can see a little left to right flexing ) kinda like airplanes brace with cables.. /TT\ kinda like that but heavy duty fishing line tired to both and a piece of carbonfiber across .. should greatly stiffen the fins. and if done right would plant the fins to where they wont move at all (like stapping a package down on a truck thats too tall) ... only other thing i can think off is stiffen the turning and point jet engine down alittle so it will plant it to the ground better. no alot mabie 1-2 degree.. reasoning is the tires can only have so much grip. so you need to compensate via downforce 2-3 lbs of downforce is a big difference on such small tires... i learned that with my 120mph 2wd ruster........
what i would suggest is get the handling stiffer and go electric with a increased length and check the weight distribution of the car particularly as in high speeds and winds the lighter sides tend to lift up and did your car lean towards same side in both the crashes .
Just wanted to throw in that it sounds normal that the gyro freaks out when you do a dry run with the wheels off the ground - like that steering has no effect on the orientation of the car, so the feedback loop is broken. It's like when you take the props of a quadcopter, it'll just try to throttle up like crazy to try and get control over it's orientation unsuccessfully.
ExpressLRS control link for your radio. Also, Gyros hate vibrations. Dampening the mounting point of the gyro may help, but road vibrations may be too much for the gyro to filter out.
If you're concerned about failsafing, ditch the Spektrum gear and convert over to ExpressLRS.. You won't failsafe with it. Perhaps a more advanced flight controller might be able to help as a substitute for the gyro as well. Just some food for thought. Awesome project mate, love it 😊
As a rule of thumb turn the gyro gain right down. I usually run about 30-35% gain and it seems to do a great job. The sloppiness in the steering is another large contributing factor. Apart from replacing worn links etc... tighten the pivot balls of your front suspension arms. they usually come loose and contribute to the slop. Zero slack is the best. You were around some speed run royalty at Rossa, Raz Shiffrin is a LEGEND at setting cars up right and Kev Talbot Is an RC (and Monster Truck) God!! Huge fan of both. I really hope you get this beast back up and running soon and onward to 200mph mate! Cheers from Aus!
Absolutely correct. I play simple Rockets 2 and it's fun testing and engineering crafts of any kind in the sandbox, designer , and test and play in a physics world. Try simple Rockets 2. It's definitely up your alley
Very interesting. Gyros can be finicky & sometimes very counterproductive. I use them on all my speed cars, but learned to keep them dialed down. At first I thought I “needed” all the help I could get & turned the gyro all the way up. Couldn’t figure out why the car was all over the road. I keep an eye out for your videos & always enjoy them. It was great to see Kevin on this video & I think I heard Raz in the background also. Best of luck going forward. JOE M
"all my speed cars" Where are the videos? It's always fun to see other people's projects. Don't worry about production quality just shoot some video and upload it to UA-cam. Just don't shoot in vertical format.
@@ddegn Thanks so much for your reply. You are a very talented young man. I am just an old man that loves building fast RC cars…certainly not the best at it. I do the best I can & I get a lot of joy in the hobby that would otherwise be missing from my life. Keep up the great work. You are always a pleasure to watch.
Never compromise and don't let anyone change your mind last minute, if you fail, it's your fault. I think this crash could have been avoided with more testing of course. I think using the electric motors on the chassis and adding a weight at the height the jet engine would be mounted to do some stability testing before actually slapping you're expensive jet and fuel supply to it is the economic course of action to take. Heck, maybe even running it as a hybrid might achieve some better results for you. I don't know about the gyro, it could well be the slop in the steering that caused that crash so although it seems like it caused your accident here, I think it was just wear and tear. I can't wait to see what you do on the next car, I think custom chassis and body are the next port of call but unless you're doing fancy carbon/grp layup I can't see anything else being affordable and available apart from 3D printing but I don't know enough about that to say yeah, it's good for structural integrity and forces that the chassis would be exposed to. Anyway, I look forward to the next vid!
I'd probably try to make the car aero stabilized and ditch the gyro for what you're doing. Would be worth it to upgrade and rebuild the front end with stiffer components to get rid of the steering slop. You can also try the rear covered wheels again, but make some sort of rigid frame (maybe out of some metal?) to keep the body from sucking into the wheels.
I love your scientific approach to solving problems. People on the side only had their eyes and past experience to go on, still it was an interesting lead.
Despite all the problems, I love your ambition and "can-do" attitude. Keep up the great work mate 👍 "We learn more from our mistakes than we do from our successes." -- Every successful person ever...probably
From an engineer with 20+yrs of experience, awesome video & engineering content!! 😎👌 Also, as a speedrunner, when it comes to gyros, I prefer to keep them off. The problem that I have experienced with gyros is that if a wheel looses contact with the road while the gyro auto correct... Well, it's going to over shoot your car in the wrong direction. A tip that I'm not sure you have implemented yet is to switch the diff fluid in the front & rear diffs to 1mill, that will help keep your car in a straight line. Just some thoughts, good luck 🤞 🍀 👍
You may need a Glitch buster on the receiver. With the Gyro attached to the receiver, its pulling too much power and the receiver can't supply that power. I have this same issue with high torque servos. I put a Racers Edge Glitch Buster capacitor on it and it solved the issue.
Not many people understand this, kudos. The gyro causes the servo to do more work. If power to the rx isn't robust, the added load can cause a brown out, which may result in a crash. Most guys attribute the crash to a loss of signal, and root cause is often incorrectly identified. It takes some work to correctly identify the root issue. Fortunately there are plenty of ways to identify signal strength and voltage through telemetry, none of which were employed here, regrettably. It takes a lot of time and energy to "make your luck".
It was great to meet you at the Rossa event . My money was on the gyro being the cause of the "wobbles". I hope to see you back next year with a new speed build .
Small suggestion from DK: The car would benefit of having the tank modified, i would suggest to open it and add small plates into it, to prevent the "sloshing effect". Without this, a small correction can easy turn into a big issue during high speed and direction corrections. You will find the same in the tanks of almost all trucks transporting liquid. Cool project, keep on fighting.
These gyros get weird when there is a lot of vibration, many have the ability to be toned down with a potentiometer on the radio but I'd just not use it. The wing seems to be giving you plenty of stability at speed. Maybe turn the rates way down so the steering is very mild. Also I'd get a surface radio, it should be easier to drive with a wheel rather than sticks. Raz knows how to build a damn fine car and his perfect pass servo is epic but he comes off as a pompous know-it-all calling everything garbage and whatnot. He was doing it to Kevin in his last video too.
Hi, great attempt. Have you thought of monitoring the speed and adjusting the response of the steering accordingly. That is making the steering travel less for the same joystick input, so you have finer control at high speed. You will never want full left or right steering lock at 160kph.
I think that gyro might me a bit subpar for the task (quality gyros for RC planes go around 200€), apart from the vibrations and the EMI with the electric setup. For really high speed applications, like fast rc jets (by fast I mean 320km/h or more) usually the gyro is supplied with speed data (from a GPS or a pitot tube) to turn down the gain (until VERY low values) when the speed is high. If you decide to use a gyro again after this, I would suggest to turn down the gain to the bare minimum. You wont crash a car due to this, the worst case is having a "slow" handling, like a boat. Or better, swap that gyro with a futaba one.
I think suspension springs could help in the rear. They could allow the rake angle of aero wings, so the more they push down, the lower their angle, reducing drag.
Ah percussive maintenance! I am just going to look now and see what you've come up with, but I still think that body wasn't helping at high speeds. The fins were good, although it likely wouldn't hurt to make them more rigid. Look forward to seeing the next version of this jet car!
Cool to see something different. Definitely ditch the Spektrum radio, so many run aways with them, Futaba or Sanwa is the way to go or the Radio Link if you are doing it on more of a budget. That gyro is a budget one more aimed towards drifting, also the gain may have wanted adjusting as others have said.
If there’s one thing I’ve learned when messing with control systems is that PIDs require a ton of tuning and testing when you want to use them in a vehicle like this. This vehicle has a ton of vibration, it has to work at low and high speed, and the environment is quite unforgiving. Any tiny bump or overcompensation sends it out of control as you saw. The only way to make this gyro work at all is to do A LOT of test runs while recording gyro data, then you have to learn how to tune PIDs to perfectly balance the system, but even then sometimes you may encounter an un-tested scenario where your PID settings oscillate. Mounting it to some sort of shock absorbing system in your car + tuning out input noise would be the first steps. Also a big issue is that the gyro isn’t tuned for the speed. It’s way too sensitive and even if it has some sort of algorithm to try to compensate for any errors, one overcompensation at 100mph is already too much. I think passive stability is the way to go for this vehicle because it’s definitely possible to control it manually as you saw from other competitors, and any benefit from a properly functioning gyro would be minimal considering the risk and effort. I’ve seen a program which tunes your PIDs via AI to a technically perfect level, but I think this car can’t really do that because it’s not like you can crash it over and over again while the AI sorts the PID out. Also, look at baffling your fuel tank. If the cars oscillation somewhat matches the sloshing rate in the fuel tank then that’ll be a huge stability issue. Like carrying a big jug of water which has the same slosh rate as your steps and you can feel it try to tip you over.
Happy to help man! Really appreciate the shoutout. 🔥 This is such a cool project and I can’t wait to see where this goes! My unique build also went through some growing pains but every time out was a learning opportunity and now we’re at 185MPH! Keep going and always happy to help 🏎
thx for spoiling
@@KjekkasAron how in the world could what I said be taken as a spoiler? Unless you’re talking about my car 😂
just kidding man haha love ur vids btw
@@KjekkasAron 😂 you got me! You rock thanks so much
Sup, Kev
wooo! I made it into the vid!! thanks for the mention! was a pleasure to meet you. a few of us were using gyros, we have the futaba one. if it wobbles you can turn down the gain, but it looks like it might be picking up vibrations. i find the 3m double sided grey vba tape the best. cheers!
hi kev
Dang I thought kev would comment here I saw him dang what a crossover!!!
I new i saw kev on the footage
KEV! awesome to see you with this guy too!
Doh! 😖 wish I the car survived to get another run so I could have tried that trick with the tape and turned down the gains! The pleasure was all mine, man! Hope to see you at another event! 👍
That gyro would have been massively freaked out by the vibration. On RC helis, the gyros (flybarless units) are installed on an anti-vibration pad to help alleviate the effects, but the vibrations from rotary flight look like nothing compared the vibes you would get from running on rough tarmac. Looking at that, I'm not surprised the other guys didn't use gyros.
Yea, at those speeds the vibrations must be making the gyro think it has gone off center and then it tries to correct the movement that it's causing itself. The only way to fix that would be to record data from accelerometers and create gyro software with the right compensations.
Some of them used gyros!
Having a longer smoothing interval on the raw gyro data might help a lot with reducing vibration-induced oscillations. Only downside is the gyro becomes less responsive to sudden jerks, but I think for a speed car this wouldn't matter too much, since being smooth on the steering should help with stability at speed.
Raz Shifrin has used gyros on every one of his cars and he's one of the fastest in the speed running scene. To be fair, he uses Futaba gyros which are the best in the game (at least for cars anyways but I think they do alright in the flight world as well if I'm not totally mistaken). He has it turned waaaay down so as to not cause violent oscillations which only get worse the faster you go. Now, I know he said no one else there was using them so I don't want to rule out the possibility that Raz decided to change his setup based on the conditions on the ground but, at the same time, I'd be more than a little surprised if he did. As the old adage goes, don't fix what ain't broken. I could be wrong of course. This is just my initial take after having watched Raz for a few years and his approach to the use of available technologies in his vehicles.
@@JJayzX Believe in JESUS today, confess and repent of your sins. No one goes to heaven for doing good but by believing in JESUS who died for our sins. For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.(John 3:16)🥳❤️😁❤️
The fact no one else was using a turbine shows how interesting and unique it is. Don't let this series die. Keep it up!
RC car speedrun community seems like a fun bunch… thanks for putting them in the spotlight!!
You’re probably right about the slop in steering causing your oscillations. Might be worth adding some stabilized rudder surfaces and leave the main steering unstabilized
An aero-stabilized short-wheelbase RC car? Hang on, this isn't rctestflight!
@@bob2859 Believe in JESUS today, confess and repent of your sins. No one goes to heaven for doing good but by believing in JESUS who died for our sins. For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.(John 3:16)🥳❤️😁❤️
I LOVE how you always showcase your “mistakes,” and reframe them as learning experiences; especially with your infectious positive attitude about how much you’ve learned. This is such a great example to show my young niece and nephew; well actually for anyone for that matter! Thanks for sharing this fascinating video with us!!!
Believe in JESUS today, confess and repent of your sins. No one goes to heaven for doing good but by believing in JESUS who died for our sins. For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.(John 3:16)🥳❤️😁❤️
My first thought was the servo. For those kind of speeds you probably want something heavy duty and pretty rigid, that may be part of what caused the gyro to get confused.
Yes. In the RC heli world they match servos to the gyro and their respective capabilities are known both ways. Makes wag much less of a problem.
If the servo response rate is too slow it won’t work with a gyro it has to be fast and strong!
That’s possible but I’m sure the oscillation is initiated by the input noise from the road. Without any sort of tuning there’s absolutely no way that the gyro will be able to work properly on a bumpy tarmac at 100 mph even if the servo was a good match. People will spend dozens of hours of testing to tune a gyro for a purpose like this because of the extreme conditions.
@@Chevsilverado yes I agree my stream liner uses 2 gyros one 3 channel for the aero and a gy401 for steering, shock absorbing mounts are critical but if too soft the problem will come back just like a slow servo,I e had some bad crashes tuning gyros in and even planes it’s not much different if u have snapped a prop mid air it usually doesn’t end well lol also just as critical to the gyro as servo speed is it’s location on the chassis it greatly effects its response! Having said that most of my speed runs are on very bumpy outback Australian roads so my cars are usually tuned on rough surfaces my best pass was only 218kmh but was done on rough loose surface roads and only managed a bit over a full second of full throttle but
it’s better than the xo1 on same surface only could do 150kmh before taking flight
Nice work. That guy saying it was the fins was talking rubbish.
One of the best series yet!
Edit:
I would love to see a mini Bloodhound build with the jet engine, as this would be realistic to the actual Bloodhound. (Because you mentioned redesigning the chassis to incorporate the engine)
It is. But I’d love to see the space shuttle return
Couldn’t agree more.
Don't forget his rocket plane program, pretty cool content too and he has a rocket that hit 700km/h
@@maxlobry4508 True. I enjoy the RC cars more, but the rocket series is one of the best on UA-cam.
Or, given his penchant for classic design, something from the golden age of British speed record cars.
Gyro in a car will reach an oscillation speed due to the servo max slew speed.
You can reduce the problem by mounting the gyro on the upright so it turns with servo (or doesn’t turn with the car in a slide.
What you need to do is use a flight controller like ardurover to have gps pid position control for the whole length of the runway and onboard data logging.
I second the flight controller idea. A flight controller would allow a lot more adjustment. I'd also add pitot air speed indicator and a quadrature encoder on at least one wheel to be better speed data.
Edit: The flight controller should have either a flash chip or a SD card for black box data. Lots of great information can be logged using programs like ArduRover.
@@ddegn
Didn’t think of using a Speedo.
The gps and accelerometers are pretty good.
Believe in JESUS today, confess and repent of your sins. No one goes to heaven for doing good but by believing in JESUS who died for our sins. For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.(John 3:16)🥳❤️😁❤️
@@alunesh12345 Stop making Christians look like crazy people. Are you really Muslim trying to make Christians look bad?
Whatever you believe, stop spamming. It's EVIL.
@@alunesh12345
Why believe when you can know
The issue with the gyro is that the steering sensitivity increases with speed. Meaning at low speeds the gyro gain is correct but at higher speeds the total output gain (steering + gyro gain) has increased causing the oscillations. I would not recommend a simple gyro for this. Maybe a flight controller with GPS to dynamically change the gain correctly for the speed?
I agree, gyro's require tuning, and you are operating it in 2 distinct scenarios, so you either need to tune it for high speed, or both, def not ONLY tuned for low speed (the way you have it now). The front suspension could be replaced and/or upgraded... I don't think the platform is stable enough for high speed passes without one, or both. I would also like to see some larger/stiffer/lighter gussets on your wing, it appears to be VERY helpful.
Quad flight controllers used to have all sorts of problems with vibrations inducing signals into the gyros. It was solved with speeding up the sampling and pid-loop and with advanced filters.
I doubt that gyro has what it takes.
@@ulwur Back in the day, before advance filtering, PID controllers had TPA, which essentially softened the gain as throttle increases. I think for simple controllers (such as this car in the video) could probably work by using a programmable gyro. There are some RC car gyros that can be tuned via RC link, which allows you to mix the throttle channel with the gain.
@@kwaaaa That seems ideal. I got into building quads 6ish years ago, and I have only heard of someone using throttle P.I.D. attenuation once... it doesn't seem to be necessary on drones. This car, however, seems like an ideal candidate.
@@MrFadjule at low speed the assistance of gyros is probably not needed. So just tune it for high speed would fix it.
I guess some pesky rules might forbid the use of autonomous steering using mmWave/microwave beacons aimed along the track in a sort of nanoscale ILS guidance system? Do you have datalogging on the servo and gyro? Is there any sign of the gyro outputs maxing out? Can you map the gyro gain and PID control loop parameters to vary with speed? How about using explosafe cellular filler inside the tank to reduce sloshing? Compliant/damped mountings to reduce high-frequency vibration noise from the track surface? Kalman filters to manage measurement noise? Viscous damping and maybe spring preload of the steering mechanism to take out any backlash at the neutral position of the servo? Looks like a huge amount of fun to be had. Great seeing the evolution of this project.
Great video as always. I really like you reflecting on changes, looking for errors and being able to find them, even when they're your own.
When going on with this project, I would strongly suggest looking into landspeed record cars and their setup. All of them are low-drag, low-downforce configurations.
Especially with no wheels being driven, a rear wing makes not much sense for downforce, however the vertical stabilizer is often used in LSR cars.
The rear wing will effectively lever up your front wheels, making the car instable at speed. A front wing to counter this or even a unified "central" wing (think aircraft aerofoil upside down) might make sense, with a small vertical stabilizer at the rear.
As I said, enjoy your content and the experimenting you are doing. Have fun!
Two suggestions: ditch the spektrum radio and go for something more modern like Crossfire or ELRS. If you want to use some active stabilization, go for something that provides you with logs so you can analyze the behavior dynamically.
ELRS ftw :) crossfire at 50hz is too slow for that kind of speed :P
ELRS with a flight controller to load the data and filter sensor input.
After watching a few times just something I'd like to add. Thrust angle from the jet is quite important. Jet cars for drag racing and landspeed actually slightly angle the jet downwards. Which seems counter intuitive but that's where your downforce comes in the trick here is balancing your downforce and thrust angle.
Failed in creating a 100mph car but succeeded in gaining valuable information on how to get to a 100mph car SAFELY and RELIABLY. Not to mention tips and contacts from the event who have the same pursuit. That's a win for any engineer and glad you think the same way!
perhaps some kind of steering damper. it's something motorcycles also use at high speed to prevent a "death wobble" (kinda what your car is doing)
I'd invest more into the suspension. An inwards toe angle makes the car want to go in a straight line, where an outwards toe angle makes the steering more responsible but the whole car way more unstable. Positive caster also helps with stability. Camber can be used to reduce the patch area.
Believe in JESUS today, confess and repent of your sins. No one goes to heaven for doing good but by believing in JESUS who died for our sins. For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.(John 3:16)🥳❤️😁❤️
@@alunesh12345 Barakaka Allah feek.
Now while the sons of Israel were in the wilderness, they found a man gathering wood on the sabbath day. Those who found him gathering wood brought him to Moses and Aaron and to all the congregation; and they put him in custody because it had not been declared what should be done to him.read more.
Then the Lord said to Moses, “The man shall surely be put to death; all the congregation shall stone him with stones outside the camp.” So all the congregation brought him outside the camp and stoned him to death with stones, just as the Lord had commanded Moses.
Numbers 15:32-36
Damn man, I'm 36 years old and have had an engineering mindset my entire life despite not going to school for it. To see someone your age making a jet powered RC car, then crashing, and having such a positive attitude about it, fills me with a lot of confidence about future generations. Keep developing your passion, by the time your my age your GOING to engineer something truly epic, and I can't wait to see it. Subscribed!
Your experiment did NOT FAIL at all. What it did was teach you a lesson and how to overcome it. I say that's a win win. I can't wait to see the new car!! You got this!!!
It's so cool seeing Kev, Raz, and Project Air all interacting!
Two things need attention immediately before you move forward. 1st. Spectrum radios are prone to interference from high power wifi telemetry. We proved this at Flite Fest when people fly near the pump out in the field. When it pulses its data (and this is not bias for radio types) spectrum radios tend to fail safe if within the direct path of that pulse. I assume an airport uses similar devices for various things they need to track. Look into that or swap radios or receivers for better.
Second: Gyros are SUPER sensitive. Vibrations will drive them bonkers specially if it hits a resonant frequency. IF you intend to use one then you need to look into some kind of soft mounting to isolate the gyro from any part of the body. Bumps and bouncing usually won't effect them to much if the gain is set properly. A resonance however will totally bork the system and may as you saw induce a drift or totally lock what ever it is controlling. (This is actually what I think happened on this particular run but the radio stuff needs to be checked in any and all cases)
Spektrum radios are great but have some of the shortest ranges of radio systems I have used.
For this job maybe you could look at some other radio systems used for long range drone flying or something like that.
Kevin uses the "Dumbo" RC radio, it might be better for this type of project.
i like how the replay feature lets you see that you are not the only one that skipped the sponsored ad
Really interesting attempts and development iterations. Being into liquid rocket hobbies my first glance at your construction made me wonder why you haven't slush plates in your fuel tank? The fuel might start oscillation wildly at an unpredictable speed because of this. Might just be one of several reasons in combination. It would be easy to eliminate this, just by filing the tank half way up with a few large metal spiral chips from a lathe or from drilling.
Yeah that was a thought that crossed my mind too.
Just rebuild the steering with all metal, high precision parts so it has no slop. Put rudders on the fins and have the gyros operate those instead of the steering. Experiment with speed dependent actuation %. The faster it goes, the less correction to prevent applying so much steering input it makes the car turn too much. Another thing to look into is detecting oscillation caused by the gyro. In that case it should return the rudders to neutral and hold them until wobble stops. If two rudder servos are used, they could be both turned to maximum outwards to act as air brakes.
One more thing, mount the engine with a little bit of upward tilt at the rear to push the rear end down. Having it parallel to the chassis is going to make it rock forward, putting more force on the front wheels. That will put more drag on the front, less on the rear, leading to amplifying the effects of steering and wanting to spin around - resisted only by the big fins.
Need to mount the jet very low and as far forward as you dare - Use some duct work for intake and exhaust. You could use a venturi effect for the jet thrust to create some downforce by sucking some air out from under the car. If the centre of drag/lift is behind the centre of mass it shouldn't go out of control so badly, and at speed it will become even more stable.
Jet engine for suction? That's a easy way to ingest as much debris as possible.
Was looking for a comment like this. The amount of thrust is just too much for a car that light, it completely dominates any aero the car has.
Pulling the car forward with a front mounted engine seems like an obvious (and not particularly pleasing to look at) solution.
the c/g is off where it is.. it needs to be 50/50 or 70/30 its better for a jet engine to drag on the ground then push in my opinion...
I think making a custom purpose built car is the way to go. Incorporate the engine into the chassis and really stiffen it up. Make some suspension components where you can control the wheel geometry (adding a bit of caster into the front steering wheels will help greatly at high speed). Beef up the steering servo as well for rigidity and crash resistance. Even make a new new body shell out of fibreglass or carbon fibre to cover the chassis and engine as one piece. Don't really need to worry about too much weight as you're after top speed instead of top acceleration (though heaps of weight would make steering difficult). Fantastic vid as always 🙂
Here's some suggestions which hopefully may help before it's next run.
Cut out the body around the engine so you can lift it on and off easily.
Turn down the steering 'dual rate' on the transmitter to about 60%, it'll make it less 'twitchy'.
If you run the gyro make sure the gain isn't too high, you only want the gyro to assist, not totally control.
Add a separate failsafe or kill switch for the engine so you can kill it remotely if possible using an aux channel.
Swap the receiver out for an aeroplane receiver as it will give you more range.
Hope that helps :)
Agreed. The engine shouldn't need to be removed to access the fuel tank. I'm sure he'll make these changes. It looks like he was rushed this time.
You could add an fpv camera to get a drivers pov, instead of turning around everytime the car passes and hoping you go off track (plus the help of the gyro). You can also go even further than you used to because you can see everything in front of you. The only problem being cost.
Great series! I think it would be really useful if you installed some fpv gear on the car so you could more easily steer it and get oscillations under control faster
Development is never a failure. The information you gleaned from this is invaluable.
Yup someone is falling into the deep rabbit hole of RC speed runs :), great vid and awesome seeing Kevin in there as well.
Speedrunning RC's is no joke... gyro's are amazing tech if set up properly. another trick we speedrunners use is turning down the dual rate of your controller so any steering inputs are dulled out a bit more. (you can also do this with negative exponential values). Dont get your head down. I got out of the game after a nasty crash that totalled my ride but the thrill of watching your build go by can't be beat. Good luck out there!
You've demonstrated one law that affects many hobbies. Others in the hobby will be quick to tell you what you're doing wrong, with little, to no evidence to back it up. Following their advice blindly would have seet you back. Every hobby has these people.
I’m not an engineer but here’s my unsolicited $.02 anyways.
It would add some drag but I would recommend pointing the front of those massive fins inwards so if the tail goes to the right the left fin will be more streamlined and the right side will cause more drag pushing the tail back to the left. In a weird way this would act like dihedral in a wing and be positively stable both statically and dynamically. Also ditch the gyro though I would have tried it too just like you.
Great vid BTW
I have a theory. If you are pushing it with thrust from the rear of the car it's less stable. My theory is that you move the engine to the front and give it just the right angle to keep it slightly pushing down similar to the current setup but slightly more and sorta have the chassis be following along. This would increase the downforce and imo increase stability. The large upright wings would still be needed. Very neat project you have. Lots of luck to you
Robert Goddard, is that you???
@7:00 yes - that is exactly what I was thinking you need. If you can get that engine down low into the body it will be a game changer. Take a look at how a jet dragster or top fuel dragster is set up to go 300+ miles an hour in a quarter mile.
Amazing work. I would add dividers in the fuel tank to stop the fuel sloshing around, and lower the engine as much as possible by cutting out some of the moulded shell and 3D printing a aero housing.
This is truly how educational content should be presented - highly valuable and greatly enjayable.
Loved this project. Would love to see you push forward with this 👍🏻🍻
Great work and I like the attitude never rely on what some one thinks they saw there is a reason they cover new rockets in engineering cameras. Good luck with the new build.
Why don't you position the jet engine even lower and make scoop for air intake.
That’s a good idea
Maybe u should place d engine as low as possible and then use an s duct to feed it air
Plus the oscillation might just b caused by the car wanting to take off, u might want to work on generating more downforce
Looking forward to more projects 😃😃😃
gyro's are programed to work at acceleration around g (10 m/s), it gives different outputs at higher accelerations. you can use accelerometer for correcting gyro's output.
I don't think this is correct.
Accelerometers are used to correct a gyro's sense of "up" in a flight controller. Gyros drift over time but the type used in the video don't need this sort of correction since it's only tracking a single axis of rotation.
As soon as I saw you were at Rossa I knew Kevin Talbot might appear in it somewhere.
Also heard Raz Shifrin giving some design pointers as he makes some insane speed cars.
Now I just have to wait to see their videos of the event and Kev showing us your car in his video.
So amazing to see. You have influenced the way I do my projects now
Gyro gain and non isolated plus steering slop. Bin it off the steering and add it to the vertical stabilisers with rudders. Also use a quad flight controller with inactive so you can data log. They are cheap enough and you can use car or boat profiles. Also, spectrum and loss of signal, who’d of thought it.
The reason for some of the issues is due to your braking i believe, if i remember correctly you are braking with the back wheels.
Full-size cars brake predominantly on the front wheels for a reason. When you are braking with the back wheels you are essentially moving the center of stability forwards, past the center of gravity. You see this effect when you are driving on ice and use the handbrake. rotating wheels have higher lateral grip than spinning/sliding wheels.
The wing helps to counteract this, keeping the center of stability behind the center of mass until you lose enough speed, at which point you lose control. This might also be why it stopped wobbling when the motor gave full gas again, just to crash.
A relevant example with wheels and grip that may be worth mentioning, when you are braking and accelerating you are essentially borrowing lateral grip.
When a FWD car accelerates too hard in a corner they crash front first
When a RWD car accelerates too hard in a corner they crash ass first.
the same holds true with front brake vs handbrake.
The fact that the center of thrust is above the wheels is probably also adding to this, by putting more pressure on the front wheels during acceleration. Cars which use a normal motor which spins the wheels have a center of thrust that is both at ground level, and is in the same direction as the ground itself.
Yes to me it also looks like the wings actually was the reason for it not to perform worse in the wobble period 🤓
Sorry to write this, but you are wrong. You can have a blown up tire on the front wheels of your car and control it safely to the stand. But a blown up tire on the rear wheels will spin you out of control. The back wheels is what is stabilizing your motion. The front wheels are for steering the car. The same goes for braking. If you brake only on the front, you move the braking point in front of the center of mass, making the car instable. If you brake on the rear, you move the braking point behind the center of mass.
The pitch of the car towards the front while braking (forced by the suspension) moves the center of mass also to the front and makes it necessary to have bigger brakes on the front than on the back.
@@Craftlngo Part of that is exactly what i'm describing. The back wheels is what stabilizes the motion, when you brake to the point where the wheels start to slide you lose lateral traction. This is why braking only on the rear wheels causes you to lose control.
Braking to the point of sliding is analoguos to the tire blowing up, just to a smaller amount.
Braking the back wheels to the point of sliding moves the center of stability forwards by an immense amount. This is what i described at the end with the braking on ice.
I am sorry if that was unclear.
Something i also have to say is that the center of mass is always the same, What changes when you brake is not the center of mass, but the direction of "acceleration".
All things experience 9.8 m/s/s, ie a 1-60 accelaration of about 3 seconds constantly, That is gravity.
When you brake you add an additional force - deacceleration. That force if it equals 1g(9.8 m/s/s) moves the direction of acceleration 45°, putting the center of pressure on the wheels forwards, which makes the traction act as if the center of mass is moved forwards.
@@Ganbalf ah ok, English is not my native language. Quite likely that I didn't understood a part correctly.
Awesome project. When attending meets like that, there will always be the "I know better" kind of people, especially when you're new in the group. Some are worth listening too. Others just love the sound of their own voice. You did a good job verifying the issues with the design. Since it's experimental on many levels, there are no real rules how to go about it. You can't be first while following someone else's footsteps.
To throw my hat in the ring, I'd consider having a separate channel for the gyro and actually give the stabilizing fins air rudders and a lightning fast servo. It's only at high speeds you need the assistance, and by then the rudders should give adequate correction force while allowing for a quicker response since the servo won't have to fight against the centrifugal forces of the spinning wheels.
Cheers!
Hi, I think I have a really easy improvement with large benefit: The oscillation is dramatically worsened by your fuel tank. Look at a tanker for example. They have ridges inside of the tank to stop the fuel from flapping arround too much
Sorry for the late comment. Enjoying watching this jet car go. I caught it at the end of the video. Loss of signal and the fail-safe problem. That problem starts with the DX6e. The e models don't have the diversity antenna system. The single antenna has good range to the sides of the transmitter, but if you point the antenna towards your car, plane, whatever, you are effectivity putting it in the cone of silence. I happen to like and use Spektrum for flying. Just not the e model transmitters. I've seen planes lost because of antenna being pointed towards the bird at half the distances I fly out to with only a dozen dropped frames on my DX18. I'd bury that 6e in a shallow grave at midnight and upgrade to a full DX6, 8 or better before attempting another speed run. Good luck and keep the vids coming.
Piece of advice, don't take aerodynamics advice from people who are not experts. Trust your own testing and then make any Nessasary changes. Good luck.
14:45 You say that the wheel wobble didn't happen without the gyro, but it clearly was. It looks like the gyro is trying to compensate for that slight wobble, but with the slop in the system and possibly some resonance from the fins it can't get there. I would look at rebuilding the front end then tuning the gains on the gyro.
It would be great if you could funnel the flow of that venturi from the jet exhaust entering the tube through slots in the base frame to get ground suction like some of the fan suction race cars of the past
Someday I'd like to see a hobbyist build a simple laser guiding system that you could just place at the end of the track so the car would home automatically to it. Steering a high speed RC car is just a recipe for disaster. The gyro is a good idea though!
I agree with you,the gyro was to sensitive,any play in your steering will exaggerate the gyro compensation,I would run without gyro and a small degree of tow out on the front,this should help to keep it running straight,hope you have mire success on the next run I watch in anticipation 👍
You're bringing the heat at the event up, and I can totally see how you could have made that error with the radio. Heat is no joke - I've had heatstroke exactly once, while I was a camp counselor, and I never want to experience that again.
Stay hydrated, homies! Seriously, though, hot weather can be a killer, especially if you're not used to it.
200mph+ on electric rc car already achieved ... interresting project but so far from improving that record, was thinking like non rc world where jet powered are unbeatable !
How fast theoricaly can push those rc jet ? Keep it up ;).
I appreciate you adding the error search at the end. Not as entertaining, but immensly insightfull
A couple more tips for improving handling,heavier silicone oil or smaller valves in the shock’s and more spring rate on the rear will do more than fuel line,also you need Less front traction! You want to go straight so put grip on the back and as much as you can! and a set of Harder compound tyres on the front, if using foam you can shape the front tyre’s so it acts like extreme negative camber ie not cylindrical but conical profile the added benefit is the narrow point of tyre touching the road is easier to compress and will absorb more bumps and more aerodynamic! Hope this helps!
100% the Gyro gain causing that 'oscillation'. I'm not sure how much you can turn it down on them ones. If you are going to continue to use one, have a look at the Onisiki 3 Axis one. Super precise and easily adjustable gain from your Tx. Look forward to seeing this hit triple figures. (Edit: watched till the end...yes, agree, slop and gyro) :)
I love how the Genius's in the trade are so supportive and un-biased towards further ingenuity. What a great Hobby... If only Government could be as transparent as this with their invisible budget to explore exotic tech
Your experiment was no failure . You learned from it , knowledge is invaluable
I’m not an engineer, so I’m sorry if I’m dumb for even suggesting this, but if you wanted the covered wheels with it having no chance of it rubbing against… maybe try putting two runners (would be part of the frame) along either side of the vehicle, similar to modern go-karts, attach the cover on top of that? Just a thought, might have other unforeseen consequences though. Either way, love this! First jet-powered RC I’ve ever seen. And it’s beautiful
14:45 you can see the wheels slightly expand from the wheels spinning so fast which I think is pretty cool as is. I would so love the opportunity to mess around with a jet turbine though
I don't think it's a good idea to disagree with the designer of the best limitless wing on the market. His cars don't oscillate at over 190 mph with much stronger cross winds.
The gyro wouldn't have been overcompensating if there hadn't been an oscillation in the first place. You made a giant sail behind the rear axle.
good job... suggestion tho.. i would brace the wings to the frame via supports to the frame at the top (in last testing you can see a little left to right flexing ) kinda like airplanes brace with cables.. /TT\ kinda like that but heavy duty fishing line tired to both and a piece of carbonfiber across .. should greatly stiffen the fins. and if done right would plant the fins to where they wont move at all (like stapping a package down on a truck thats too tall) ... only other thing i can think off is stiffen the turning and point jet engine down alittle so it will plant it to the ground better. no alot mabie 1-2 degree.. reasoning is the tires can only have so much grip. so you need to compensate via downforce 2-3 lbs of downforce is a big difference on such small tires... i learned that with my 120mph 2wd ruster........
Yessss! Amazing build
love that you included kev
Colin, COLIN! Yeah your lads at it again, yeah the Jet thing, yeah I don't know but it's on fire pal.
More of this project please, it’s awesome!!!!!
what i would suggest is get the handling stiffer and go electric with a increased length and check the weight distribution of the car particularly as in high speeds and winds the lighter sides tend to lift up and did your car lean towards same side in both the crashes .
Just wanted to throw in that it sounds normal that the gyro freaks out when you do a dry run with the wheels off the ground - like that steering has no effect on the orientation of the car, so the feedback loop is broken. It's like when you take the props of a quadcopter, it'll just try to throttle up like crazy to try and get control over it's orientation unsuccessfully.
ExpressLRS control link for your radio. Also, Gyros hate vibrations. Dampening the mounting point of the gyro may help, but road vibrations may be too much for the gyro to filter out.
The best scientists show their mistakes and failures. You are awsome!
If you're concerned about failsafing, ditch the Spektrum gear and convert over to ExpressLRS.. You won't failsafe with it.
Perhaps a more advanced flight controller might be able to help as a substitute for the gyro as well. Just some food for thought.
Awesome project mate, love it 😊
Приветствую любителей турбо-реактивной тяги!
As a rule of thumb turn the gyro gain right down. I usually run about 30-35% gain and it seems to do a great job. The sloppiness in the steering is another large contributing factor. Apart from replacing worn links etc... tighten the pivot balls of your front suspension arms. they usually come loose and contribute to the slop.
Zero slack is the best.
You were around some speed run royalty at Rossa, Raz Shiffrin is a LEGEND at setting cars up right and Kev Talbot Is an RC (and Monster Truck) God!! Huge fan of both.
I really hope you get this beast back up and running soon and onward to 200mph mate! Cheers from Aus!
Absolutely correct. I play simple Rockets 2 and it's fun testing and engineering crafts of any kind in the sandbox, designer , and test and play in a physics world. Try simple Rockets 2. It's definitely up your alley
Very interesting. Gyros can be finicky & sometimes very counterproductive. I use them on all my speed cars, but learned to keep them dialed down. At first I thought I “needed” all the help I could get & turned the gyro all the way up. Couldn’t figure out why the car was all over the road.
I keep an eye out for your videos & always enjoy them. It was great to see Kevin on this video & I think I heard Raz in the background also. Best of luck going forward. JOE M
"all my speed cars"
Where are the videos?
It's always fun to see other people's projects. Don't worry about production quality just shoot some video and upload it to UA-cam. Just don't shoot in vertical format.
@@ddegn Thanks so much for your reply. You are a very talented young man. I am just an old man that loves building fast RC cars…certainly not the best at it. I do the best I can & I get a lot of joy in the hobby that would otherwise be missing from my life. Keep up the great work. You are always a pleasure to watch.
Never compromise and don't let anyone change your mind last minute, if you fail, it's your fault. I think this crash could have been avoided with more testing of course. I think using the electric motors on the chassis and adding a weight at the height the jet engine would be mounted to do some stability testing before actually slapping you're expensive jet and fuel supply to it is the economic course of action to take. Heck, maybe even running it as a hybrid might achieve some better results for you. I don't know about the gyro, it could well be the slop in the steering that caused that crash so although it seems like it caused your accident here, I think it was just wear and tear. I can't wait to see what you do on the next car, I think custom chassis and body are the next port of call but unless you're doing fancy carbon/grp layup I can't see anything else being affordable and available apart from 3D printing but I don't know enough about that to say yeah, it's good for structural integrity and forces that the chassis would be exposed to. Anyway, I look forward to the next vid!
I'd probably try to make the car aero stabilized and ditch the gyro for what you're doing. Would be worth it to upgrade and rebuild the front end with stiffer components to get rid of the steering slop.
You can also try the rear covered wheels again, but make some sort of rigid frame (maybe out of some metal?) to keep the body from sucking into the wheels.
No disaster there, great learning project, you did say you were running to its limit and now you know allot more.. very interesting
I love your scientific approach to solving problems. People on the side only had their eyes and past experience to go on, still it was an interesting lead.
Despite all the problems, I love your ambition and "can-do" attitude. Keep up the great work mate 👍
"We learn more from our mistakes than we do from our successes." -- Every successful person ever...probably
From an engineer with 20+yrs of experience, awesome video & engineering content!! 😎👌
Also, as a speedrunner, when it comes to gyros, I prefer to keep them off. The problem that I have experienced with gyros is that if a wheel looses contact with the road while the gyro auto correct... Well, it's going to over shoot your car in the wrong direction.
A tip that I'm not sure you have implemented yet is to switch the diff fluid in the front & rear diffs to 1mill, that will help keep your car in a straight line.
Just some thoughts, good luck 🤞 🍀 👍
You may need a Glitch buster on the receiver. With the Gyro attached to the receiver, its pulling too much power and the receiver can't supply that power. I have this same issue with high torque servos. I put a Racers Edge Glitch Buster capacitor on it and it solved the issue.
Not many people understand this, kudos. The gyro causes the servo to do more work. If power to the rx isn't robust, the added load can cause a brown out, which may result in a crash. Most guys attribute the crash to a loss of signal, and root cause is often incorrectly identified. It takes some work to correctly identify the root issue. Fortunately there are plenty of ways to identify signal strength and voltage through telemetry, none of which were employed here, regrettably. It takes a lot of time and energy to "make your luck".
It was great to meet you at the Rossa event .
My money was on the gyro being the cause of the "wobbles".
I hope to see you back next year with a new speed build .
Small suggestion from DK:
The car would benefit of having the tank modified, i would suggest to open it and add small plates into it, to prevent the "sloshing effect".
Without this, a small correction can easy turn into a big issue during high speed and direction corrections.
You will find the same in the tanks of almost all trucks transporting liquid.
Cool project, keep on fighting.
These gyros get weird when there is a lot of vibration, many have the ability to be toned down with a potentiometer on the radio but I'd just not use it. The wing seems to be giving you plenty of stability at speed. Maybe turn the rates way down so the steering is very mild. Also I'd get a surface radio, it should be easier to drive with a wheel rather than sticks. Raz knows how to build a damn fine car and his perfect pass servo is epic but he comes off as a pompous know-it-all calling everything garbage and whatnot. He was doing it to Kevin in his last video too.
Hi, great attempt.
Have you thought of monitoring the speed and adjusting the response of the steering accordingly.
That is making the steering travel less for the same joystick input, so you have finer control at high speed.
You will never want full left or right steering lock at 160kph.
I think that gyro might me a bit subpar for the task (quality gyros for RC planes go around 200€), apart from the vibrations and the EMI with the electric setup. For really high speed applications, like fast rc jets (by fast I mean 320km/h or more) usually the gyro is supplied with speed data (from a GPS or a pitot tube) to turn down the gain (until VERY low values) when the speed is high.
If you decide to use a gyro again after this, I would suggest to turn down the gain to the bare minimum. You wont crash a car due to this, the worst case is having a "slow" handling, like a boat. Or better, swap that gyro with a futaba one.
I think suspension springs could help in the rear. They could allow the rake angle of aero wings, so the more they push down, the lower their angle, reducing drag.
It was a pleasure meeting you buddyx
Was so strange to suddenly see Kevin lol. Never would've expected you two to meet
Ah percussive maintenance!
I am just going to look now and see what you've come up with, but I still think that body wasn't helping at high speeds. The fins were good, although it likely wouldn't hurt to make them more rigid. Look forward to seeing the next version of this jet car!
Cool to see something different. Definitely ditch the Spektrum radio, so many run aways with them, Futaba or Sanwa is the way to go or the Radio Link if you are doing it on more of a budget. That gyro is a budget one more aimed towards drifting, also the gain may have wanted adjusting as others have said.
good job on figuring out what the problem was!
If there’s one thing I’ve learned when messing with control systems is that PIDs require a ton of tuning and testing when you want to use them in a vehicle like this. This vehicle has a ton of vibration, it has to work at low and high speed, and the environment is quite unforgiving. Any tiny bump or overcompensation sends it out of control as you saw. The only way to make this gyro work at all is to do A LOT of test runs while recording gyro data, then you have to learn how to tune PIDs to perfectly balance the system, but even then sometimes you may encounter an un-tested scenario where your PID settings oscillate. Mounting it to some sort of shock absorbing system in your car + tuning out input noise would be the first steps. Also a big issue is that the gyro isn’t tuned for the speed. It’s way too sensitive and even if it has some sort of algorithm to try to compensate for any errors, one overcompensation at 100mph is already too much.
I think passive stability is the way to go for this vehicle because it’s definitely possible to control it manually as you saw from other competitors, and any benefit from a properly functioning gyro would be minimal considering the risk and effort.
I’ve seen a program which tunes your PIDs via AI to a technically perfect level, but I think this car can’t really do that because it’s not like you can crash it over and over again while the AI sorts the PID out.
Also, look at baffling your fuel tank. If the cars oscillation somewhat matches the sloshing rate in the fuel tank then that’ll be a huge stability issue. Like carrying a big jug of water which has the same slosh rate as your steps and you can feel it try to tip you over.