Building the world's biggest rubber powered airplane, pt.2
Вставка
- Опубліковано 29 вер 2024
- All materials supplied by Windcatcher RC. All carbon in this build is available directly from Windcatcher. windcatcherrc....
Part 1: • Building the world's b...
Part 3 flying: • Rubber Band Airplane W...
Music from RoyaltyFreeMusic: pixabay.com/mu...
Support the dream: / joshuawfinn
Like us on Facebook: / jhaerospace
Builder's group: www.facebook.c...
Instagram / joshuawfinn
Learn about indoor freeflight: indoornewsandv...
Tiktok: www.tiktok.com...
![[UA] Eternal Fire проти NAVI | EPL Season 20 Malta](http://i.ytimg.com/vi/chvlsDygrZM/mqdefault.jpg)
I still can't believe the size of that monster. It's difficult to understand until you see the scale of it while you are holding it. You did a fantastic job designing and building it.
I had help and inspiration from the best!
When is the next video please?
@@davidfranklin5270 Soon... very soon. 😁
I enjoy every one of your videos, Josh, but this series is something special. Please don't keep us waiting much longer to see this beast in the air! Guaranteed to be spectacular!
Glad you're enjoying it! Flight footage is coming soon!
@@joshuawfinnAnxiously waiting for the maiden flight here. Hey, that would be an interesting name for it: "Rubber Maiden"
What a monster well done indeed---- no specs posted, what is the span, weight, prop size?
Like he said, 300% of 68" Dawn Patrol, with exceptional 200% fuselage cross section and prop diameter.
Check the front page at jhaerospace.com
Everybody watching this knows why you are doing this, we're right there with you.
You definately need a bigger prop diameter. McCombs, Make Model Airplanes Fly, says prop diameter in inches should be at least 1.5 times the square root of wing area in square inches. The larger diameter prop, with its larger swept area, moves a larger volume of air with lower acceleration, with greater efficiency. You want the largest diameter you can fit; the limitation is ground strikes. You are not going to ROG this plane, so that limitation does not apply. The blade angle distribution should be the (helical) advance angle in level flight plus the attack angle of maximum L/D for your blade profile. For our little airfoils, that is going to be somewhere around 4 to 6 degrees. What is your prop advance ratio?
For maximim still air duration, the average torque of the motor should correspond to the apogee torque, the torque at which the plane flys level. I find torque (gm cm) to weight (gm) ratios from about 0.76 to about 1.24, averaging around 1.0. The high 1.24 is for the AMA Cub with its low aspect ratio flat wing. The 0.76 is for the Dandiflyer, with its high aspect ratio cambered wing. Your plane, with its slender fuselage, high aspect ratio cambered airfoil, will likely be at the low end of ths scale. That allows us to calculate the optimum torque if you know the weight of the airplane. Torque allows us to calculate motor cross section for maximum still air duration.
Well, for max performance, yes. However the torque requirements for a full sized propeller are beyond my physical abilities. You would need over 200 in-oz just to get a cruise climb going with the 78" propeller, on roughly 48 strands of 1/4" rubber. Besides the need for an electric winding rig on a gantry, there's also the hazard of what happens in a motor breakage. The smaller prop lets me get a slow climb going at around 100 in-oz, and a pretty substantial climb at anything above 140 in-oz.
Keen for part 3!
Can you please make a build video for the 2024 Stinger kit, I really need to for SciOly :)
Use the 2023 vid and the new manual. The only difference with the new one is it's simpler and has the option for an extended Div B wing.
@@joshuawfinn Okay then, thank you :)
chase it with a paramotor? surely there's someone with a paramotor that would be happy to help :)
I need to look into that in the future. A very good idea.
What is Bud Romak's take on this monster?
Bud absolutely loves it!
Seeing it with wings is breathtaking!
i cant believe you didnt let us see the test glide !
Gotcha! Yeah just wait, it's coming!
I can think of loads of reasons for doing this. Thanks to all at J&H Aerospace and at Windcatcher RC for this fantastic series! Can't wait to see how this goes. Nice one guys! ⭐⭐👍
❤Amazing. Hello from europe. Czech republik. I seen you First Time with flie test and you 8motor springouse house... I love it. Can you make a video about that? That rubbed power plane is what all 5 years i cant understand. Amazing and wanted.... Big fan from europe. Thank!
I'm still working on making a full video on that bird. It will happen eventually. Just gotta get some other stuff done first.
The oddity on the amount of giant scale rubber powered plane projects I’ve been seeing the past year. While not substantiated, Think Flight also built a massive rubber plane scaled off the little profile balsa toys.
It's called an arms race. 😉 seriously though it just gave me the push I needed to finally do this. So glad I did!
I follow!
But the bigger the plane gets, the more harder to make it. But big planes fly nicer.
I started with cl at twelve years old, and then rc., Now that im 57 years old.
Very true, in all respects!
I am waiting and are very 🤩 exited, this is great.
Wow…going to be totally epic 👍👍👍…now to find that thermal 😃
Thank you!
Have you thought about drilling a hole at a shallow angle from the bottom of the nose block so you can put a pin to keep the prop from turning? That way it can be pulled out from behind the prop as you're launching.
I had planned to do that but ran out of time to address the issue of how to make the blades stay open when the prop was readied for launch with the pin in place. Hoping to get that taken care of over the winter.
legend status!
Has quinea hens, is driven and brilliant. Definitely a .000001 percent individual.
Completely bonkers, love it!
Simply AWESOME! (literally)
Proves the saying. "The only differencw between men and boys is the SIZE and cost of the toys". I wish I could get paud to have so much fun. Eagerly waiting for the fliggt videos. Keep up the great content.
Thanks David! It's been a fun adventure!
How about a twin engine this size. Small central fuselage with a long pod on each wing for the rubber.
I pondered it, but couldn't figure a good way to deal with two motors on something this big.
Looks like one item in a modeler's bucket list.
Absolutely!
As far as I can tell this is one extremely long boring commercial, fly the damn thing already!😮
Watch the latest video. ;)
When is the next video installment? You have us all dying in anticipation!😮
I'm literally waiting for a music copyright license to clear before I can release it. It's driving me nuts waiting!
Preliminary engineering estimates for rubber motors.
Assume airframe weight of 4.91 lb = 2,227 grams (yes, I know, gram is a unit of mass, not weight, but guess what, we weigh everything in grams and the 980s cancel out), torque to weight ratio 0.75, motor length 95 inches, apogee torque coefficient 20,772, we get 38 strands of 1/8", motor weight 0.675 lb, apogee torque 26.38 in oz, breaking torque 131.92 in oz, maximum turns 2,243, at a revolution rate of 22 rps, 1 min 42 seconds.
You can manage a motor about twice the available distance, make it 190" long. We get 42 strands of 1/8", motor weight 1.54 lb, apogee torque 30.17 in oz, breaking torque 150.84 in oz, maximum turns 4,290, at a revolution rate of 22 rps, 2 min 15 seconds.
You are doing it, not because it is easy, but because it is hard !
Yes!!!
Josh, have you measured the apogee torque and revolution rate of your largest planes? You could do such testing on the present configuration. That can guide the sizing of the prop and motor for this one. I suspect a larger prop will be more efficient, will deliver the same thrust with less torque or more thrust with the same torque. The larger prop will be heavier, but it is a marginal increase on the total weight, so the increase on required power will also be marginal. The larger prop will have a lower revolution rate, giving a longer mtor run.
🤞🤞🤞🤞🙂
what D/t system did you use.?😊😊
It's a BMK B2 RDT. The flying video has some closeups of it.
Nylon bolts might be adequate for the fuselage joint. Keep it light and add lightness.
Rough engineering estimate. Torque to weight ratio, should be verified by test, assume low 0.75. Weight; aircraft 4.91 lb + motor 1.13 lb (could change on test) = 6.04 lb = 2,740 grams. Multiply by 0.75 Q/W to get 2,055 gram centimeters of torque, = 28.5 inch ounces cruise torque. Breaking torque is typically about five times average torque, 143 inch ounces. Your 200 in oz winder is adequate.
Unfortunately nylon bolts for the fuselage join proved insufficient, but it flies alright anyway.
Extraordinary model!!! I'm super anxious to see the video showing your historic record setting attempt, but I'm just as interested to find out how much that magnificent airplane WEIGHS! Best wishes to you and everyone else who is involved in this incredible project. I have good feelings about this!
Get ready, it goes live tomorrow!
Can't wait to see part 3.
This is absolutely bonkers and I love it 😂
That was such a tease stopping the video just at the moment of the test glide 😂
Yeah we had fun with that!