It's remarkable to see just how consistent the entire skin of the aircraft looks, the machined tooling has paid off so well. Most aircraft of this scale have noticeable waves and irregularities just all over the surface
We designed split rudders into the Lynx suborbital space plane we were developing at XCOR for similar reasons- it allows speed brake function and also was much simpler to actuate given their locations at the wingtips. We were also able to include a slight preload against the stop to provide greater resistance to flutter, important in a supersonic aircraft.
Always a great presentation… Tungsten makes an interesting choice. Density, and doesn’t corrode at ordinary temperatures of aircraft operation…. And not soft like lead. There is a recent AD for these elevator balance weights on a popular airplane because the weight was cast in a tube… and corrosion formed between the lead and the tube…. The corrosion forces expansion and the weight tries to fall apart. The problem took 20+ years to appear… but, once started the rate of oxidation increases, exacerbating the problem… Go DarkAero! 😃
Really proud of you guys, I have been following you guys for 3 YEARS. If I get a visa to the US, I must come and visit you guys. The consistency is amazing.
I used to fly the SAAB 340 and it had the most amazing redundant elevator system. Basically the left control column controlled the left half of the elevator and the right control column controlled the right half of the elevator. Normally they'd work together as one unit as there was a friction and mechanical plate that meant that if one side moved the other side moved as well. But crucially if part of the system jammed you could overpower the linkage between the two sides and still be able to operate at least half of the elevator. I always thought this was an amazing way to provide redundancy.
Nice, heim joints, bell cranks and torque tubes, with not a whole lot of translation, so backlash should be minimal. You might want to also mention that the control surface weights, by projecting up into the airstream forward of the hinge point, also help manage control forces at higher airspeeds. The split rudder works VERY effectively as a speed brake, I use them this way all the time on my Cozy. I am curious what you're using as a rudder return spring - it looks like you're using push-pull cables to actuate each rudder, but I don't see space inside the rudder for a spring assembly - is it at the pedal end? If so, how do you plan to prevent buckling of the cable in push near the pedals if there is resistance at the rudder end? You'd need a decent sized spring to overcome the friction of a push/pull cable that long. Do you engage the brakes master cylinders only after you get full rudder pedal travel? How do you ensure you can land with the rudders deployed, but without the brakes deployed? (I'm assuming the nosewheel is full castering?) Lastly, I didn't see the roll servo, I'm curious as to where it's going to end up - it looks the only practicable place is behind the seats?
- How I heard it, the rudders are independent - with only a pull cable (spring return to centre) - ??, is the rudder deviation only from centre to full lateral deflection (left or right) ? - OR having no centre stop, the lee side rudder (low pressure) just follows the pressure side (half) to full deflection under spring action? - using the airbrakes on a steep straight-in approach sounds kind of similar to balancing regular toebrakes for yaw control, from the sound of it.. hmmm... Some high performance lightweight RC craft also only use a (single acting) pull cable (kevlar thread/kite-line often used) for tail unit control, the tension is maintained by spring tension as is full tension deflection - balanced by servo force - (spring-pull rudder and elevator - no tensioning problems or slop can intrude)
I think they're making a mistake with the split rudders in the way they have them designed. They really need to follow each other at least somewhat past centerline for the first third of their travel before splitting, with canard aircraft a little misalignment doesn't come with a drag penalty but it certainly will with a split rudder, and especially so with conventional tractor configuration slipstream hitting the vertical. There will only be a single speed and throttle setting in which the two rudders are streamlined and together, the rest of the time one or the other will be split, meaning you'll always have a small amount of airbrake deployed. The rudder pedals should also be interconnected in their movement with airbrake function as a separate lever to actuate that simply moves two pulleys to shorten the rudder cables. This would allow standard toe brakes to be used instead of pushing the pedals to the floor and forcing the airbrakes open in order to make the toe brakes work, or having to use the dreaded piper style hand brake. You may not always want to use brakes with the airbrake deployed for whatever reason, and not being able to put any pressure on the rudder pedals during flight to avoid deploying the airbrake is going to suck.
Great video, as always. In addition to clearly explaining the basic operation of your control system, I especially liked how you quickly touched on the considerations that went into the design; such as goals to minimize friction, backlash, compliance, and weight while also ensuring easy of service.
I never tried the split rudder although I thought a lot about it. I have flown canard aircraft so I understand the speed brake part of it. Good job! Also it looks like you have some differential in the ailerons. Very good! Something I did a lot was flattening and widening the aileron counterweights so they tuck up inside the wing tips only when the aileron deflects down but the weight enters the wind stream when the aileron deflects up. This adds some parasite drag to the to the up aileron side of the aircraft thus reducing the amount of rudder required to maintain coordinated flight. It's good to see some young people that know how to think out good design. Keep it going and be careful. Thanks for the videos!
What about ICING inside the split rudder design? Will you test the push force overcoming ice adhesion? Another option is adding heat for safety. Love the concept, but Ice and Breaking concern me.
Is there an expected loss in rudder authority with your design compared to conventional designs, since only half of the rudder deflects with say a right rudder input. Wouldn't the fact the left half of the rudder remains within the line of the airflow "block" some of the airflow from adhering to the interior side of the deflecting right rudder and therefore reduce effectiveness?
It looks like it shifts the air flow point of indecision on the leading edge so that more air will flow over the clean side and move with higher speed giving more lift. Will it be _efficient_ and forceful enough for fighting *repeating* turbulent air gust rapid wing rises or more importantly immediate effective and powerful spin recovery? Imagine an inadvertent spin at aft C.O.G. with those pretty, narrow wings.
The independent rudders are great. A very safe way to operate a speed brake without forgetting the boards are out. Yes, this happens, even with highly trained and experienced airline pilots they forget to stow the speed brakes.
Man. She is really coming together nicely. I really can't wait to see how that split rudder works out. Seems like a great way to add drag when you want it to slow down such a slippery plane.
I agree. I imagine there's a small aerodynamic penalty to using split rudders. I'm pretty sure the split rudder has more drag in use than a conventional rudder. Having a speed brake likely makes any loses worth it.
@@fdelacou- It could replace flaps for giving drag while reducing altitude without gaining airspeed. Won’t add lift for slower takeoff and landing speeds though.
@@fdelacou NO. Flaps increase lift and drag, important to minimize and bleed KE during landing. Lift is critical for this. Flap extension is typically not allowed at high speeds due to high loading they can create.
Interesting rudder/spead brake. One thing I wonder about is propeller slipstream. On the Rutan canard airplanes the vertical stabs and rudders are outside the spiraling slipstream. On the DarkAero, it will be in the slipstream. I'll be interested to see how you deal with that, as well as rudder trim. My understand (which could very well be wrong) is that on the Rutan canards, the rudders on the winglets is more about creating drag rather than lift. Same goes with split style of flaps on other airplanes. I'm not an aeronautical engineer so I might be all wet... I'd like to see your split rudder act more conventionally with the rudder pedals and have a separate mechanism to split them. Kind of like the A-10 ailerons do. Hmmm... Or.... Leave the rudder conventional an put the speed brakes on the ailerons just like the A-10's! Keep up the good work.
I agree with you. Rutan design is based on drag. In conventional control surfaces it’s the back side of the control surface that moves the airframe. It’s a wing you might say creating lift. Left rudder input means the right side of the vertical fin and right side skin of the rudder making a positive airfoil moving the tail in the left direction. I question if this will work well. I’m not an engineer but have been designing and building model aircraft all of my life for 50 years or so. Have studied design for decades. I guess we will know one day. Great project!!!
You might want to consider a lockout for the split rudder for takeoff and climb. Canard flyers of various makes have had issues during engine outs of panic stomping on both rudder pedals, exacerbating the emergency. This is of course, alleviated with training. Also, a lockout would keep the passenger from inadvertently inputting while shifting their position, ect.
The ability to flip a switch to convert the rudder(s) into a single control surface would inherently be safer. (If this function is actually desired) Failures to the pins/flanges shouldn't lead to any particular dangers.
Very interesting rudder design, really clever double identity for a rudder. However, even though I don't see this bird doing dive bombing, the dive bombers in WWII also had an air brake, which didn't work until they poked it full of holes. Before the holes, the dive flaps ripped themselves off the airplane in some dives. There's going to be quite a vacuum in between your rudder panels. They're also small, unlike the surfaces of a dive brake, so making them work without unexpected consequences should be easy. Holes near the very front of the control surface should do, and won't interfere with the forward flight aerodynamics of the surface, but it will do the pilot and structure a favor. They can be made as decorative as they are functional.
11:00 instead of increasing the arm length to balance it, what if u add a cavity inside the wing and have the aileron elongated along the entire tail, distribute the weight in a short depth and it doesn't interfere with the airflow?
8:15 i've always wondered why more planes don't have that, its like a really easy way to reduce speed. glad to see the team incorporating that design into your aircraft though, keep it up.
TECHICAL PTS ONLY Your rudder is just skin. It should've ribs. Otherwise, it gonna collapse under aero load, locking its hinge, making it catastrophic. Too many linkages providing failure pts. Trim tabs is another set of failure points...Instead give trim tabs on stick like RC model Longer control horns proportionally minimize backlash.
I didn't see any mention that the long torque tubes through the wings, at the cabin, don't pivot at the tube? Hard to explain, and I don't have the correct vocabulary to properly describe, but watch closely at around the 6:00 mark. The inboard bell cranks are anchored on one of the ears?! Is it very weird that the inboard ends of the torque tubes move up and down in space?
+1 for rudder trim! Not always needed… but always appreciated! Really nice for those long climbs to altitude… and extra speed during the descent. Kinda like a yaw damper for the auto-pilot too… not a requirement, but really nice to have in the bumps… Don’t fly sideways! 😃
Ngl, I love everything about the split rudder aside from the control scheme you've selected. Conventional rudder pedals (push one and other moves opposite) with a seperate speed brake lever similar to what youd see on a jet's throttle quadrant would be much better as far as avoiding inadvertent speed brake application and making the transition from other aircraft more seamless.
I have now watched every one of your videos, some more than twice. Its wonderful to witness the evolution of modern design and materials taken to their absolute limits for your mission. The videos are so informative, easy to understand, and the plane is absolutely gorgeous. When it comes time for a DarkAero II, how do you feel about a plane with a 55mph stall speed, fixed gear, fixed pitch prop, 200mph cruise, similar mega-range? Come on, add a couple of feet to the wing, a couple of inches to the cockpit, use that UL520T so we can outclimb the weather - this will be an rv-14 killer. AKA, something us mortals can safely handle and still get insurance for (not to mention have a better resale value)... Just food for thought, keep up the good work, and keep the videos coming.
Do you have enough leverage for one hand to over come the forces on the ailerons control surfaces? If you have 1:1 ration on the torque tube then the only lever advantage is the length of the stick. 🤔🤔🤔🤔🤔🤔
Also, is there a deliberate or inadvertent elevator input when the control sticks are deflected in the aileron axis? I LOVE the control setup, by the way!
@@joelighty409I asked Riley about this in a q & a. He replied that the elevator deflection from applying aileron would be very small and that the pilot would typically add some nose up pitch to compensate for increased bank angle.
Please explain the split rudder more. I see impact force vs lifting force as one side stays flat (stream lined) while the other is inducing drag. Is the concept the same? Are there efficiencies in stabilization with the split rudder?
I don't get this either. The VariEze uses the split rudder to add a little extra pro-yaw drag out at the tips as well as the normal yaw moment, but I can't see the advantage of this on DarkAero because you're adding extra drag down the centre-line.
You guys are awesome! Everything is very well thought out. The split rudder is a great feature. Using it to slow the plane down is very nice. I have to ask, in turns, does the other half, the straight half, hinder the turning ability of the turning half, enough to notice? Do the halves open up enough to maybe offset any drag? Again, great job! I hope to have the money to buy one of your airCRAFT one day! Take care
I didn’t hear anything about designing out flutter? This is of great technical interest to me. It is also the practical speed limit for many airframes, assuming they have lots of hp like this one. Would especially be applicable to high powered turbo normalized aircraft
They mentioned braking forces… for slowing down, or descending… Or, are you asking about how the structure physically handles the added forces while braking? 😀
@@AC-jk8wq Yea I’m more wondering about the mechanical structure. When that planes going hundreds of miles an hour I imagine the forces are huge and you can’t really see any of the mechanism.
It looks like it's castering (ua-cam.com/video/H8Ugh2fzd0I/v-deo.html) but this still involves controlling the braking mechanism. I didn't look carefully for past videos on this.
I like the split rudder as an air brake. But I hope you have considered how the airplane will react in flight with only half of the surface deflecting? With this, you are splitting the airflow, creating a void of air forming low pressure pocket behind the airplane. This means any time you use the rudder (usually at low speed TO or landing) you are adding a lot of drag, which could decelerate the plane at a critical moment. Another negative aspect I foresee is that while one side is deflecting, the other side is still in place, acting as a vertical stabiliser. I believe this will negate a lot of the effective yaw control and may require a lot more deflection to get an adequate response. Just my thoughts. Would love to see how you guys have tested this concept.
The drag force is reduced at lower speeds, and it's likely that the aerodynamic force when using normal rudder input will pull the opposite rudder along (unless the surfaces are blocked from moving across the center point).
As always the ailerons will create some adverse yaw that will have to be counteracted by rudder. Unfortunately the split rudder is going to cause a lot of drag during routine turning.
Why didn't you do the mass balances internally? On the elevator couldn't you have a longer mass balance arm inside the fuselage hanging off the torque tube. Same with the Ailerons off their torque tubes?
Clever design choice with the split rudder/airbrake. For better or worse, this style of airbrake doesn't reduce lift when deployed. Wing spoilers have the benefit of increasing tire traction, although I suppose they have their own concerns, such as difficulty in packaging without a drag penalty. I'm curious how the split rudder's drag compares to a hinged rudder at modest deflections (e.g. trimmed for P-factor at cruise).
How bad is the performance loss during initial climb when using a lot of right rudder? It seems like you’d be trying to climb with the speed break basically partially deployed if you have a consistent rudder input in
Great and enjoyable videos. My question is, is the darkaero going to have a pressurized cockpit?. However is the build of a pressurized cabin just dependent on the strength of material only or how is modelling a design for a pressurized cabin achieved, are there computations?
it's much easier to do pressurized with a round cross section like a balloon. This plane is more boxy. It's not impossible but flat parts need very high strength and the canopy edge and latching mechanisms have to be very strong as well. The 'glass' would be thicker too. Or would have less glass, more or a hard top with pillars like a car, maybe. No pressurized GA plane has been done with a clear canopy afaik but not impossible. Fighter planes have it.
I am predicting the rudder will be changed after flight tests. It would be more sensible to let the split rudder stay together as it moves left and right and only opens up when a speed brake is actually required. Easy enough to do with a mixer. On an aircraft designed for utmost efficiency, getting a drag brake opening every time you use the rudder makes no sense.
Tons of single point failures in their design for sure! The ailerons are also single rod controlled instead of a typical push-pull twin rod setup. Even the split rudder effectiveness with the short rudder couple length has me thinking they won't have much rudder effectiveness at lower airspeeds with lower prop blast at lower power.
How are you guys running brakes and steering with top mount lever pedals? And will there be anything in place to ensure that resting on the pedals isnt going to cause constant airbrake? Also how are you accounting for the need for trim?
I noticed you have an elevator servo connected to the linkages. The rudder control cable system as well as the ailerons do not show servo’s though you did mention servo’s related to a future video on the split flaps if I heard you correctly. At the very least having some sort of trim tab on the rudder would significantly lower the pilot workload on long distance flights. Could this form the basis for a 2 or even 3 axis autopilot system?
Every one of these videos teaches me something. You make complex concepts understandable, and most importantly, you give your audience credit for having enough intelligence to follow along with you. Much appreciated.
Have you seen an aircraft toroidal propellor yet? A few have shown up in 3D prints for drone props… But, I haven’t seen anything since the wave of initial interest… Great question! Lots of added weight, way out on the nose, creates a lot of design hassle…. It would be nice if it has real benefits…. To match the hassle…. 😃 The DarkAero team would be a great group to make it happen.
Love these videos. Would you be willing to do a video on the business model/plan? Curious how you see the DA fitting in around the Lancairs and RVs of the world
Great work in there, thanks for sharing this video. One question, why choose one split rudder movement to stop in the yaw and not make it all the way together with the other part? Wouldn't this create a greater drag while yaw?
Very cool, congrats on the innovative design! I'm still looking forward to HS taxi testing/ TO roll testing. I looked at the similarities/differences between the DarkAero and a TBM for TO roll (for P-factor). They are somewhat (loosely) the same. The TBM has a large rudder, and needs it to hold center line on TO. It will be interesting to see if the split-rudder will also hold center line at full TO power. I'm rooting for you guys! 8) --gary
It's remarkable to see just how consistent the entire skin of the aircraft looks, the machined tooling has paid off so well.
Most aircraft of this scale have noticeable waves and irregularities just all over the surface
It's bright white, lol.
@@FarmerFpvplenty of other white planes out there
A&P pilot here, can’t thank you enough for all of the knowledge you’re giving! Keep it up and can’t wait to see the first flight!
This whole project is phenomenal. I wish you lads the very best of luck in the future!
We designed split rudders into the Lynx suborbital space plane we were developing at XCOR for similar reasons- it allows speed brake function and also was much simpler to actuate given their locations at the wingtips. We were also able to include a slight preload against the stop to provide greater resistance to flutter, important in a supersonic aircraft.
Always a great presentation…
Tungsten makes an interesting choice. Density, and doesn’t corrode at ordinary temperatures of aircraft operation…. And not soft like lead.
There is a recent AD for these elevator balance weights on a popular airplane because the weight was cast in a tube… and corrosion formed between the lead and the tube…. The corrosion forces expansion and the weight tries to fall apart. The problem took 20+ years to appear… but, once started the rate of oxidation increases, exacerbating the problem…
Go DarkAero!
😃
Great explanations and great looking airplane! Reminds me Mike Arnold's AR-5.
Thanks a lot for sharing
Really proud of you guys, I have been following you guys for 3 YEARS. If I get a visa to the US, I must come and visit you guys. The consistency is amazing.
I used to fly the SAAB 340 and it had the most amazing redundant elevator system. Basically the left control column controlled the left half of the elevator and the right control column controlled the right half of the elevator. Normally they'd work together as one unit as there was a friction and mechanical plate that meant that if one side moved the other side moved as well. But crucially if part of the system jammed you could overpower the linkage between the two sides and still be able to operate at least half of the elevator. I always thought this was an amazing way to provide redundancy.
Nice, heim joints, bell cranks and torque tubes, with not a whole lot of translation, so backlash should be minimal. You might want to also mention that the control surface weights, by projecting up into the airstream forward of the hinge point, also help manage control forces at higher airspeeds.
The split rudder works VERY effectively as a speed brake, I use them this way all the time on my Cozy.
I am curious what you're using as a rudder return spring - it looks like you're using push-pull cables to actuate each rudder, but I don't see space inside the rudder for a spring assembly - is it at the pedal end? If so, how do you plan to prevent buckling of the cable in push near the pedals if there is resistance at the rudder end? You'd need a decent sized spring to overcome the friction of a push/pull cable that long.
Do you engage the brakes master cylinders only after you get full rudder pedal travel? How do you ensure you can land with the rudders deployed, but without the brakes deployed? (I'm assuming the nosewheel is full castering?)
Lastly, I didn't see the roll servo, I'm curious as to where it's going to end up - it looks the only practicable place is behind the seats?
- How I heard it, the rudders are independent - with only a pull cable (spring return to centre) - ??, is the rudder deviation only from centre to full lateral deflection (left or right) ? - OR having no centre stop, the lee side rudder (low pressure) just follows the pressure side (half) to full deflection under spring action? - using the airbrakes on a steep straight-in approach sounds kind of similar to balancing regular toebrakes for yaw control, from the sound of it.. hmmm...
Some high performance lightweight RC craft also only use a (single acting) pull cable (kevlar thread/kite-line often used) for tail unit control, the tension is maintained by spring tension as is full tension deflection - balanced by servo force - (spring-pull rudder and elevator - no tensioning problems or slop can intrude)
I think they're making a mistake with the split rudders in the way they have them designed. They really need to follow each other at least somewhat past centerline for the first third of their travel before splitting, with canard aircraft a little misalignment doesn't come with a drag penalty but it certainly will with a split rudder, and especially so with conventional tractor configuration slipstream hitting the vertical. There will only be a single speed and throttle setting in which the two rudders are streamlined and together, the rest of the time one or the other will be split, meaning you'll always have a small amount of airbrake deployed. The rudder pedals should also be interconnected in their movement with airbrake function as a separate lever to actuate that simply moves two pulleys to shorten the rudder cables. This would allow standard toe brakes to be used instead of pushing the pedals to the floor and forcing the airbrakes open in order to make the toe brakes work, or having to use the dreaded piper style hand brake. You may not always want to use brakes with the airbrake deployed for whatever reason, and not being able to put any pressure on the rudder pedals during flight to avoid deploying the airbrake is going to suck.
Great video, as always. In addition to clearly explaining the basic operation of your control system, I especially liked how you quickly touched on the considerations that went into the design; such as goals to minimize friction, backlash, compliance, and weight while also ensuring easy of service.
I never tried the split rudder although I thought a lot about it. I have flown canard aircraft so I understand the speed brake part of it. Good job! Also it looks like you have some differential in the ailerons. Very good! Something I did a lot was flattening and widening the aileron counterweights so they tuck up inside the wing tips only when the aileron deflects down but the weight enters the wind stream when the aileron deflects up. This adds some parasite drag to the to the up aileron side of the aircraft thus reducing the amount of rudder required to maintain coordinated flight. It's good to see some young people that know how to think out good design. Keep it going and be careful. Thanks for the videos!
Such a gorgeous plane
Mmm ok
What about ICING inside the split rudder design? Will you test the push force overcoming ice adhesion? Another option is adding heat for safety. Love the concept, but Ice and Breaking concern me.
Very good point.
How is ice going to get inside an aft-facing gap, when it is closed together for the entire duration of the flight?
Is there an expected loss in rudder authority with your design compared to conventional designs, since only half of the rudder deflects with say a right rudder input. Wouldn't the fact the left half of the rudder remains within the line of the airflow "block" some of the airflow from adhering to the interior side of the deflecting right rudder and therefore reduce effectiveness?
It looks like it shifts the air flow point of indecision on the leading edge so that more air will flow over the clean side and move with higher speed giving more lift. Will it be _efficient_ and forceful enough for fighting *repeating* turbulent air gust rapid wing rises or more importantly immediate effective and powerful spin recovery? Imagine an inadvertent spin at aft C.O.G. with those pretty, narrow wings.
Your project is next level. Love it!
Great video as always!
The independent rudders are great. A very safe way to operate a speed brake without forgetting the boards are out. Yes, this happens, even with highly trained and experienced airline pilots they forget to stow the speed brakes.
Man. She is really coming together nicely.
I really can't wait to see how that split rudder works out.
Seems like a great way to add drag when you want it to slow down such a slippery plane.
The split rudder is so sick
I agree. I imagine there's a small aerodynamic penalty to using split rudders. I'm pretty sure the split rudder has more drag in use than a conventional rudder. Having a speed brake likely makes any loses worth it.
Was wondering if that could be a replacement for ... flaps. Thoughts?
@@fdelacou- It could replace flaps for giving drag while reducing altitude without gaining airspeed. Won’t add lift for slower takeoff and landing speeds though.
No! Not sick but good!
@@fdelacou NO. Flaps increase lift and drag, important to minimize and bleed KE during landing. Lift is critical for this. Flap extension is typically not allowed at high speeds due to high loading they can create.
Beautiful thinking . It made me happy as same as seeing Beautiful paintings
How will you handle constant yaw inputs in cruise flight? Won’t a constant split be inefficient?
Like any airplane, the pilot has to learn its quirks. The cork of this is you can't push hard on both of the rudder pedals at the same time
Interesting rudder/spead brake. One thing I wonder about is propeller slipstream. On the Rutan canard airplanes the vertical stabs and rudders are outside the spiraling slipstream. On the DarkAero, it will be in the slipstream. I'll be interested to see how you deal with that, as well as rudder trim. My understand (which could very well be wrong) is that on the Rutan canards, the rudders on the winglets is more about creating drag rather than lift. Same goes with split style of flaps on other airplanes. I'm not an aeronautical engineer so I might be all wet... I'd like to see your split rudder act more conventionally with the rudder pedals and have a separate mechanism to split them. Kind of like the A-10 ailerons do. Hmmm... Or.... Leave the rudder conventional an put the speed brakes on the ailerons just like the A-10's!
Keep up the good work.
I agree with you. Rutan design is based on drag. In conventional control surfaces it’s the back side of the control surface that moves the airframe. It’s a wing you might say creating lift. Left rudder input means the right side of the vertical fin and right side skin of the rudder making a positive airfoil moving the tail in the left direction. I question if this will work well. I’m not an engineer but have been designing and building model aircraft all of my life for 50 years or so. Have studied design for decades. I guess we will know one day. Great project!!!
Always informative guys!
You've probably already answered this but how is trim done?
thats awesome! i have to put this rudder into my next rc model thanks!
You might want to consider a lockout for the split rudder for takeoff and climb. Canard flyers of various makes have had issues during engine outs of panic stomping on both rudder pedals, exacerbating the emergency. This is of course, alleviated with training. Also, a lockout would keep the passenger from inadvertently inputting while shifting their position, ect.
Does a control lockout not have its own safety challenges?
You wouldn't want to lock out the rudders during takeoff, climb, or any other phase of flight since they are required for directional control.
@@DarkAeroInc only lock out the split rudder functionality. When locked, it should behave as a conventional single rudder
The ability to flip a switch to convert the rudder(s) into a single control surface would inherently be safer. (If this function is actually desired) Failures to the pins/flanges shouldn't lead to any particular dangers.
@@codeforge3301 This is what I meant to convey. Thanks.
Very interesting rudder design, really clever double identity for a rudder. However, even though I don't see this bird doing dive bombing, the dive bombers in WWII also had an air brake, which didn't work until they poked it full of holes. Before the holes, the dive flaps ripped themselves off the airplane in some dives. There's going to be quite a vacuum in between your rudder panels. They're also small, unlike the surfaces of a dive brake, so making them work without unexpected consequences should be easy. Holes near the very front of the control surface should do, and won't interfere with the forward flight aerodynamics of the surface, but it will do the pilot and structure a favor. They can be made as decorative as they are functional.
I was going to mention the drag. If you need to fly with a trim, you'd be flying with a parasitic drag. Anyway, yours went well beyond that!
They didn't have carbon fiber back in WW2. But it is a good idea if they need to.
@@LawyerPapa Ouhhh thats a solid concern.
This project is hugely inspiring, you guys rock! Cheering you on
11:00 instead of increasing the arm length to balance it, what if u add a cavity inside the wing and have the aileron elongated along the entire tail, distribute the weight in a short depth and it doesn't interfere with the airflow?
8:15 i've always wondered why more planes don't have that, its like a really easy way to reduce speed. glad to see the team incorporating that design into your aircraft though, keep it up.
Is there any increased icing risk in the split rudder?
TECHICAL PTS ONLY
Your rudder is just skin. It should've ribs. Otherwise, it gonna collapse under aero load, locking its hinge, making it catastrophic.
Too many linkages providing failure pts. Trim tabs is another set of failure points...Instead give trim tabs on stick like RC model
Longer control horns proportionally minimize backlash.
Your explanations are always so good and easy to understand, great project!
I didn't see any mention that the long torque tubes through the wings, at the cabin, don't pivot at the tube? Hard to explain, and I don't have the correct vocabulary to properly describe, but watch closely at around the 6:00 mark. The inboard bell cranks are anchored on one of the ears?! Is it very weird that the inboard ends of the torque tubes move up and down in space?
Was wondering about flaps. Glad I'm subscribed (11:40).
Do you have a rudder trim system ?
+1 for rudder trim!
Not always needed… but always appreciated! Really nice for those long climbs to altitude… and extra speed during the descent.
Kinda like a yaw damper for the auto-pilot too… not a requirement, but really nice to have in the bumps…
Don’t fly sideways!
😃
We don’t have rudder trim on the prototype, but it wouldn’t be hard to implement if a builder wanted it.
Ngl, I love everything about the split rudder aside from the control scheme you've selected. Conventional rudder pedals (push one and other moves opposite) with a seperate speed brake lever similar to what youd see on a jet's throttle quadrant would be much better as far as avoiding inadvertent speed brake application and making the transition from other aircraft more seamless.
ngl, yeranidiot see my comment above
I'm excited for DarkAero! Approximately when will the maiden take place?
You won't get an answer..five years in so far
You guys are SO LUCID. Actual role models
I have now watched every one of your videos, some more than twice. Its wonderful to witness the evolution of modern design and materials taken to their absolute limits for your mission. The videos are so informative, easy to understand, and the plane is absolutely gorgeous.
When it comes time for a DarkAero II, how do you feel about a plane with a 55mph stall speed, fixed gear, fixed pitch prop, 200mph cruise, similar mega-range? Come on, add a couple of feet to the wing, a couple of inches to the cockpit, use that UL520T so we can outclimb the weather - this will be an rv-14 killer. AKA, something us mortals can safely handle and still get insurance for (not to mention have a better resale value)... Just food for thought, keep up the good work, and keep the videos coming.
This plane looks so good, love your vids, thanks
That is a pretty sweet looking plane! ✈️
Do you have enough leverage for one hand to over come the forces on the ailerons control surfaces? If you have 1:1 ration on the torque tube then the only lever advantage is the length of the stick. 🤔🤔🤔🤔🤔🤔
Cool. Please get into more details.
You may have covered it elsewhere, but I would be interested to hear about the flutter considerations for your split rudder assembly.
Also, is there a deliberate or inadvertent elevator input when the control sticks are deflected in the aileron axis? I LOVE the control setup, by the way!
@@joelighty409I asked Riley about this in a q & a. He replied that the elevator deflection from applying aileron would be very small and that the pilot would typically add some nose up pitch to compensate for increased bank angle.
Thanks!@@rickhearn5899
excelente video, keep it up
Can't wait for the first flight. Amazing work guys.
Impressive work.
Are there no vortexes produced at the end of the wings, increasing drag?
I would love to see the pedals in the cabin to see how the brakes operate with the split rudder system. Please include that in a future video!
The most advanced airplane 🛫 today 🛫🤙🏻🏆☝🏻💪🏼 looking forward to more videos ty
How does the breaking system work, in conjunction with the split rudder?
"braking"... but that's a good question.
When the rudder is split (both rudder pedals depressed), it creates aerodynamic drag. It has nothing to do with the hydraulic brakes on the wheels.
@mgd3333 yes, but it's still a valid question - how does the wheel brake control work?
Toe brakes I'm sure@@brianb-p6586
We need so many more videos. Just normal everyday stuff. These are awesome
Please explain the split rudder more. I see impact force vs lifting force as one side stays flat (stream lined) while the other is inducing drag. Is the concept the same? Are there efficiencies in stabilization with the split rudder?
I don't get this either. The VariEze uses the split rudder to add a little extra pro-yaw drag out at the tips as well as the normal yaw moment, but I can't see the advantage of this on DarkAero because you're adding extra drag down the centre-line.
You guys are awesome! Everything is very well thought out. The split rudder is a great feature. Using it to slow the plane down is very nice. I have to ask, in turns, does the other half, the straight half, hinder the turning ability of the turning half, enough to notice? Do the halves open up enough to maybe offset any drag? Again, great job! I hope to have the money to buy one of your airCRAFT one day! Take care
I didn’t hear anything about designing out flutter? This is of great technical interest to me. It is also the practical speed limit for many airframes, assuming they have lots of hp like this one. Would especially be applicable to high powered turbo normalized aircraft
Hey does your kit include one of those sweet creeper chairs ?
Can you talk a little about how the split rudder is able to handle the high air drag forces when both sides are out?
They mentioned braking forces… for slowing down, or descending…
Or, are you asking about how the structure physically handles the added forces while braking? 😀
@@AC-jk8wq Yea I’m more wondering about the mechanical structure. When that planes going hundreds of miles an hour I imagine the forces are huge and you can’t really see any of the mechanism.
How do the wheel brakes work with split rudders?
Is there an interlock of sorts that keeps the rudders from going into speed brake mode while in flight?
Very cool. You didn't mention nose gear steering. How will that work? Maybe include with the secondary controls discussion?
It looks like it's castering (ua-cam.com/video/H8Ugh2fzd0I/v-deo.html) but this still involves controlling the braking mechanism. I didn't look carefully for past videos on this.
Yes they chose to go with a free castering nose wheel. Steering is handled by differential breaking and rudder at high ground speed.
With the rudder pedals doing so many things, how do you apply the brakes?
Are you guys concerned about the pressure drag vector that is opposite the way you are trying to yaw due to the split rudder?
Why is your elevator torque tube off the center of rotation? Space constraints?
Still wondering how the mechanism works, can you make a detailed video on how those flaps controlled ?
I like the split rudder as an air brake. But I hope you have considered how the airplane will react in flight with only half of the surface deflecting?
With this, you are splitting the airflow, creating a void of air forming low pressure pocket behind the airplane. This means any time you use the rudder (usually at low speed TO or landing) you are adding a lot of drag, which could decelerate the plane at a critical moment.
Another negative aspect I foresee is that while one side is deflecting, the other side is still in place, acting as a vertical stabiliser. I believe this will negate a lot of the effective yaw control and may require a lot more deflection to get an adequate response.
Just my thoughts. Would love to see how you guys have tested this concept.
The drag force is reduced at lower speeds, and it's likely that the aerodynamic force when using normal rudder input will pull the opposite rudder along (unless the surfaces are blocked from moving across the center point).
I like the sleek CF fuselage. No rivets.
As always the ailerons will create some adverse yaw that will have to be counteracted by rudder. Unfortunately the split rudder is going to cause a lot of drag during routine turning.
thanks question: you dont need to balance split flaps or split ruder right? this question includes balance via weight and aiirodynamicaly.
Nice one! Guess next month the video will be about flaps and trims? And what about the antennas? I’m really curious about those…
From the first minute of the video I was wondering the same thing. Where are the flaps and trim tabs?
they have been doing this for years, never seen anything fly.@@rmarsh3309
Can't wait to see it fly.
Amazing video as usual. Just curious to know which camera do you use? The auto focus is sharp, fast and accurate.
Why didn't you do the mass balances internally? On the elevator couldn't you have a longer mass balance arm inside the fuselage hanging off the torque tube. Same with the Ailerons off their torque tubes?
Adding, this has been a fantastic project to witness and learn!
this
Why is the fuselage so long? Could the cruising drag be reduced if the empennage is closer to the cockpit?
Love the plane! One question though, how do your wheel brakes work? Guessing no toe brakes?
Clever design choice with the split rudder/airbrake. For better or worse, this style of airbrake doesn't reduce lift when deployed. Wing spoilers have the benefit of increasing tire traction, although I suppose they have their own concerns, such as difficulty in packaging without a drag penalty.
I'm curious how the split rudder's drag compares to a hinged rudder at modest deflections (e.g. trimmed for P-factor at cruise).
What have you done to control adverse yaw when applying the ailerons?
Time 2:35 shows differential movement, more drag on the inside lowering wing.
How bad is the performance loss during initial climb when using a lot of right rudder? It seems like you’d be trying to climb with the speed break basically partially deployed if you have a consistent rudder input in
Great and enjoyable videos. My question is, is the darkaero going to have a pressurized cockpit?. However is the build of a pressurized cabin just dependent on the strength of material only or how is modelling a design for a pressurized cabin achieved, are there computations?
it's much easier to do pressurized with a round cross section like a balloon. This plane is more boxy. It's not impossible but flat parts need very high strength and the canopy edge and latching mechanisms have to be very strong as well. The 'glass' would be thicker too. Or would have less glass, more or a hard top with pillars like a car, maybe.
No pressurized GA plane has been done with a clear canopy afaik but not impossible. Fighter planes have it.
Are the rudders mass balanced?
I am predicting the rudder will be changed after flight tests. It would be more sensible to let the split rudder stay together as it moves left and right and only opens up when a speed brake is actually required. Easy enough to do with a mixer.
On an aircraft designed for utmost efficiency, getting a drag brake opening every time you use the rudder makes no sense.
They would be wise to have a plan B.
Is there any redundancy in the system? Seeing that the elevator is connected via a single push rod, does that mean there is a single point of failure?
Tons of single point failures in their design for sure! The ailerons are also single rod controlled instead of a typical push-pull twin rod setup. Even the split rudder effectiveness with the short rudder couple length has me thinking they won't have much rudder effectiveness at lower airspeeds with lower prop blast at lower power.
Is there a differential in the ailerons between up and down deflection or is the travel the same? Cheers and good luck.
Cant wait for the maiden flight! Do u guys have a date in mind when that will be?
One doubt, the split rudder can in thesis act differently because both sides would never act equaly and cause yaw?
How are you guys running brakes and steering with top mount lever pedals?
And will there be anything in place to ensure that resting on the pedals isnt going to cause constant airbrake?
Also how are you accounting for the need for trim?
How does the roll not bleed into pitch control? When you move the stick sideways, it seems that the pitch linkage would move a bit forward?
I noticed you have an elevator servo connected to the linkages. The rudder control cable system as well as the ailerons do not show servo’s though you did mention servo’s related to a future video on the split flaps if I heard you correctly. At the very least having some sort of trim tab on the rudder would significantly lower the pilot workload on long distance flights. Could this form the basis for a 2 or even 3 axis autopilot system?
Every one of these videos teaches me something. You make complex concepts understandable, and most importantly, you give your audience credit for having enough intelligence to follow along with you. Much appreciated.
Have you thought of including a toroidal propeller.
Reduced noise, higher performance. Amazing.
Have you seen an aircraft toroidal propellor yet?
A few have shown up in 3D prints for drone props…
But, I haven’t seen anything since the wave of initial interest…
Great question!
Lots of added weight, way out on the nose, creates a lot of design hassle….
It would be nice if it has real benefits…. To match the hassle…. 😃
The DarkAero team would be a great group to make it happen.
I'm really curious about the single split rudder. Wouldn't that increase drag any time you use the rudder in a coordinated turn?
what are you guys doing about confliced input /panic input on the rudder?
you might just end up with a huge speedbrake deployed at takeoff
Does split rudder add to STOL capabilities?
Love these videos. Would you be willing to do a video on the business model/plan? Curious how you see the DA fitting in around the Lancairs and RVs of the world
In 1965, the Payen Arbalète PA60 was already using such a system that inspired Rockwell for the space shuttle...
Great work in there, thanks for sharing this video. One question, why choose one split rudder movement to stop in the yaw and not make it all the way together with the other part? Wouldn't this create a greater drag while yaw?
Very cool, congrats on the innovative design! I'm still looking forward to HS taxi testing/ TO roll testing. I looked at the similarities/differences between the DarkAero and a TBM for TO roll (for P-factor). They are somewhat (loosely) the same. The TBM has a large rudder, and needs it to hold center line on TO. It will be interesting to see if the split-rudder will also hold center line at full TO power. I'm rooting for you guys! 8) --gary
We're spoilers considered over or augmenting ailerons in the interest of mitigating adverse yaw ??
When are we going to fly this thing?
Is right rudder only or left rudder only not going to act like an unwanted air brake ?