Have beeb flying for a year now and no trouble taking off any of my planes-nose grear or tail draggers. I figured the Cub would be no problem. Have an OS 52 four stroke in it and it is set up properly-CG , throws etc. BUT, I can't get it up to enough speed before she wants to lift off, stall and crash. I try to get it running with very little elevator just to keep the tail down on initial roll out, let the elevator neutral out and let her climb out . It has worked a couple of times but after three crashes on take off this brand new beauty is starting to look pretty beat up. One of my buddies has a Goldberg Cub and no problems. He is flying it with a Saito 65 4 stroke. Anybody out there flying this H9 Cub? What's your experience with the take offs. Some guys say all Cubs are a bear for trying to get off the ground safely. Any words of wisdom would be appreciated.

It sounds like the Cub is trying to take off with too little airpeed. Chances are very high that you have your CG too far back or you have too much positive wing incidence. Another other item to check is the thrust line. Too much downthrust would make it balloon. I would go with forward CG. As they say, "nose heavy flies poorly, tail heavy flies once".

i wore out a tail wheel groundlooping on my GP cub b4 i finally figured out how to take off. ez on throttle and after 20-30 tries it will started to become mo fun.... ...i have 2 cubs and the 60 size flies great with a ys 63. very short takeoffs and lots of power once wheeels lift off works for me. -Tinman-

If I understand you correctly, here is your problem:

"I try to get it running with very little elevator just to keep the tail down on initial roll out"

You want to hold enough up elevator initially to keep the model from tipping over on its nose when you initially apply throttle, but that is all. The goal is to get the tailwheel off of the ground as soon as possible and to steer with the rudder. This way, your Cub won't take off prematurely and stall.

Don't forget to hold a bit of opposite aileron if you are taking off crosswind. Opposite to the direction the model is trying to roll from being blown, that is. Roll the model slightly into the wind.

Good luck.

Norm,
I have the setup as you do. Hanger 9 Cub with OS 52 Surpass. Initially I had the same problem, plane would not build up much airspeed on the ground. I managed to get the plane off the ground but it was a dog in the air, just about flying. The only thing I changed was the prop and what a difference. I fly mine with a 12X6, APC. I my intial flight I had a 11X7. A 12X6 sounds like alot of prop but that 52 has no problem. I swing around 9,000 RPM and the plane flies great, plenty of power for a cub. I have about 20-30 flight on it now. Let me know if you have any questions. [email protected]

Tony Gagliardi Jr.

I had a APC 13x6 on my 52 for over 50 hours of run time, a 13 with less pitch might work better yet.

My cub was the arf and I put a OS 70 surpass on it. Absolutley a blast to fly. Takeoffs took a little getting used to. Never groundlooped or anything just fairly difficult keeping the plane straight until proper speed is established. My advice is to put a bigger 4 stroke on it and you will not believe the difference. Now that I have numerous flights under my belt with this plane, the easiest way to get it up is to gun it and 10 feet later you are airborne. Keep in mind the engine i have pulling it. In a tailslide I can pull it back over without any problems. I caught some flack at my field when I bought this plane. Now 3 of the others have gotten one. The slow low passes are AWESOME!!!!Good luck..

Keep in mind that Cubs are some of the hardest planes to take off without ground looping or premature lift-off. They look like gentle trainers, but around here it's been fun at times watching 'hot' pilots fighting a new cub all over the runway. I have an H9 with a .65 Saito and a 13 x 6 prop that will take off a sweet as a lamb if you do it right, but will bite you the first chance it gets if you goof...

• The J-3 has a very narrow stance and critical gear placement relative to CG.
• You must let the tail come w-a-y up since the shape of the fuselage bottom will fool you into thinking it's nose low when the wing is still at a positive angle of attack.
• You need toe-in on the landing gear to avoid ground loops.
• You should use a large diameter, low pitch prop and bring power on gradually. (in fact they will usually break ground before you're all the way up on the throttle)
• NO ailerons (well at least the least you can get away with) on take off. Cubs fly well on just rudder.
• If you have a computer radio, mix 20 - 25% rudder with your ailerons just in case you have to level the wings on take off and use them. - It sure improves the turns too.
• Keep it at a fairly flat climb angle and don't make hard turn inputs until you have flying speed after take-off.
• Make sure both wheels are free and one is not binding or harder to spin.

The list can go on more, but that pretty well vents my spleen -

quint

Norm
I suspect you have a wing incidense problem, too much positive relative to the horizontal stab and engine thrust line. I believe some the other guys that responded also have this problem. Too much positive incidence on a high wing, flat bottom wing, tail dragger will give just the results you got when trying to take off.
Try at least a 1/16 or better a 1/8 thick spacer under the trailing edge of the wing. I think you'll see a vast improvement.

What prop? As someone else here suggested this can have alot to do with it. My OS 52 is no powerhouse and is very sensitive to prop changes (won't make enough power with the wrong one)...

I would think 12x6 would be right with a cub, but 11x6 is my 52's favorite...

Good luck

I have the GP Cub with an OS52 on it. Os recommends you use a 12-7 and thats what I have on it. The way I see it your not getting enough speed on take off and applying to much up when it gets in the air. You have to fly it scale like. A real Cub took awhile to gain altitude.

Hey, this is just the thread I needed to read. My GP 60 cub is nearing completion. Thank goodness I don't plan to let this plane be my 2nd plane to fly! I'll be getting some stick time on the 4-star 60, Aresti, and Sig SE first.

Thanks for the tips, folks. The G2 simulator makes it seem too easy.

i have a GP 60 Cub and i have a problem taking off if i slowly apply throttle. the cub will either make a hard sharp right or left turn without warning. i toed in the gear and it helped a bit. But i have found a way that works for me. When im lined up down the runway and im ready to go, I just apply full power all at once. The Cub pulls straight, I stear with the rudder . pull back on the elevator and im airborne. Im running a saito .91 and its got tons of power.
I think part of the problem for cubs is that the main gear are placed far forward and are very close together.

Thanks for all the tips, guys. As soon as I get the Cub back together I'll try to do all that has been suggested. Norm

My h9 Cub had some up trust built in had same problems that you are having. added shims too mount so it now has 1 or 2 degrees of down thrust and it now takes off fine. Magum 4 stroke 61 and APC 12/6. Motor is not as strong as OS 52. Hope this helps also others tips on toe in etc. should help. Why do they fly better after they a dinged.

Thanks for the tip,bpannier. Makes sense to me and will pay attention to that detail when I rebuilt the firewall and replace motor mount.

Hey guys, I have some questions.

I am building a scratch built Cub from Cad plans I have and I am currious if anyone has a Cub similar to the size of mine that could give me some guideline measurements. My wingspan is 90". I have started building the wing halves and Im curious about the angle of dihedral. Also what angles of deflection are for rudder and elevator.

Also, I am using a Saito .91 engine. I bought a 13x6 prop for this plane and from reading these posts I think this is a bad choice. quint is using this same prop on a .65 Saito, so I think I could use some better advise on prop size.


For more pics on this project.

Thanks

Had a Hangar 9 J-3 powered by a De Walt drill motor with a belt reduction and a 15 x 10 prop. Bought a set of Bob Shattleroe custom spring loaded landing gear for this 10 lb beast (17 cells). This gear has a coil spring suspension and slight toe-in. Takeoffs were never a problem, but I tried to fly it in as scale-like a manner as possible: hold up elevator, slowly increase throttle, ease off on the elevator as speed builds to let the tail lift, pull back gently after top ground speed is reached. With plenty of down and right thrust I never had a torque or ballooning problem. The shock absorbing landing gear really helped smooth out touchdowns. I lost it to a vicious spin when my transmitter antenna loosened up. (Now have same power system in a Kyosho Tiger Moth, it handles crosswind better than the Cub.)

i have one with saito 90 twin it flys great with 13x8 prop, like they said keep it a little nose heavy and you dont need a lot of elv. just take your time lift off slow. scale like not stick like..

I built a 40-size cub from the great planes kit as my first plane, having no previous exposure to model airplanes, and I learned to fly on that plane. I had the help of an instructor, but it really never gave me any trouble on take-off. Just add throttle slowly and you'll be fine.

Dan, the 13 x 6 is one of my favorite props on a Saito 72. Think you need to look at a 14 or 15 inchers with low pitch for a 91.
Ed M.

At the local airport I overheard two full size pilots recalling their "early days" learning the basics in a J-3. One said he still remembers the uneasy feeling he got when his Instructor had him literally ram the stick full forward on a takeoff roll. This was to pick up that long tail back there. He said he was always scared he was going to jam the prop into the ground, but it never happened. I tried it on my R/C Cub and it worked. Once the tail is flying it's easy to steer with the rudder and it just goes on down the strip till its ready to leave. My RCM Funster had a flat bottomed airfoil shaped horizontal stab that helped get it's long tail up as soon as it began to run and with no input from me. It took off fine every time. I have a similar setup on a Crop Duster type now. Cubs with their flat tails make you do the work. If I can do it anyone can do it.

Ha... you've been used to flying sports models havent you? Welcome to the world of scale aeroplanes... a totally different ball game and a complete different technique mindset.
Yep it wants to take off at a very low throttle setting, know why? Because as a model its massively over powered compared to the full size.

Learning to taking off a Cub with finnese is one of the great RC aeroplane milestones!!! So enjoy the learning experience.

As you're experiencing trying to do it fast dosen't work. You Must go very slowly on the throttle. If you are getting airbourn at anything over 1/3rd throttle you'll going way to quickly.
As you have seen, it wants to take of it's self at a low throttle setting... it's either stalls, or you slam open the throttle and it snaps...bummer.

It has to be one slow constant movment, best practiced in very little wind to start with.

Taking off left to right with youself in the middle: I be positioning your sized aeroplane at least 20m to my left. Start advancing the throttle to make it taxi, advance a little more to a faster taxi, alittle more to an fast taxi letting the tail raise, advance again to break ground infront of me, advance again as it's getting airbourn, advance again to fly away with authority, advance again to you desired flying speed... this is done in one smooth transition, get the picture.

Forget about holding in up elevator as you take the run. If it's nosing over it's because you've used to much power... infact done correctly you'd be needing a little down elevator!

Rudder... Cub? Damn it's a sensitive mother...they can start swinging this way and that can't they?
The key again is speed or in a Cubs case, the lack of it. Any swinging on your take off run basically case for a abort! Forget it and start again. You must watch the aeroplane very carefully and input (ease in) the rudder the MOMENT you see the slightest deviation from the center line. You are new to the hobby so the aeroplane will be ahead of you 99.9% of the time and thats not a good place to be when it come to rudder correcting a Cub. Thats why we have to practice, to get to understand the aeroplane and learn it's ideosychrosise(spelling) so we'll be ahead of it!
Enjoy the proccess and good luck.