handyman

My Feedback: (2)

i give up, tried it all........the plane will not stay str8 for take off,,,,,,,,,,been flying now about 20 yrs so not new to this, what do you think,,,,,,,,and where or how would i use one

HighPlains

My Feedback: (1)

Have you tried down trim on the elevator? Get the tail flying and the rest is easy.

handyman

My Feedback: (2)

been there done that also

madsenw

My Feedback: (5)

I know the owner of Action Hobbies in Lakewood Colorado is real knowledgeable about Cubs and gyros in planes. I would give him a call 303 233 6275. It sounds like a torque issue to me. I will bet you tried this, but anyhow I use a real gentle application of power to counteract this, and I push the tail into the ground for the first 20 feet. Also, I know wider main gear can help, and turning the wheels slilghtly out or in seems to work. I dont know if I helped, but I am sure Brad at Action can fix your problem.

Best regards

RCVFR

My Feedback: (7)

Which Cub, engine, prop are you using? How is the landing gear set up? What is your take off technique with the Cub? If all else fails, I guess a gyro might have to do the job, but for someone with your experience it seems a shame to resort to that.

MinnFlyer

My Feedback: (4)

You would just put it between the Rx and the rudder servo

Live Wire

handyman
I have 3 Cubs of different sizes. If your landing gear is back under the leading edge of your wing, it will give you the fits[:@] Is there a way you can move the wheels ahead of the wing by shimming the back of your landing gear. And do check your toein other wise all they do is ground loop

And if you use a gyro on the rudder you are going to change the way it fly's.

GaGeeBees

My Feedback: (23)

I had the worst behaving Cub in the world. It was impossible to take off, even in the hands of our most experienced club members. Ultimately the only solution that worked was a simple one. We set low rates for the rudder at minimal movement and just flipped to low rates when ready for the takeoff roll. The difference was incredible and a plane that couldn't be handled on takeoff became completely docile. As soon as it's in the air I flip the switch back to high rates. Give it a try, it might work for you too.

Live Wire

Forgot to ask what Cub is it. If it is the Goldberg, with the single wire gear you are going to have fun on landing too.

handyman

My Feedback: (2)

its a GP with a 46

GaGeeBees

My Feedback: (23)

I've been flying the GP Cub since 2003. Here are two (or is it three?) of mine. No special toe-in or any of the other usual advice followed. Both fly great.

Live Wire

Just a thought , with that plate type landing gear, is the gear angle foward. I had the plate type gear on my goldberg and changed it to the wire what a mistake, going to change again to Cub type gear

Villa

Hi handyman
I have had three J3-Cubs with OS46FX engines. Love them. Have you tried feeding in the throttle slowly? Be ready with a little right rudder as needed. Abort the takeoff if it is not correct. What makes the Cub interesting for me is that it needs to be handled differently than other planes. You just have to learn what that difference is. With a Cub, you have to learn to use the rudder in the air and on the ground. Don't just apply it and hold it. Use it as the situation requires. In other words, learn how to handle the plane. When taxiing back, go slow and use some up elevator to get the rear wheel to have more authority. Go for it!

handyman

My Feedback: (2)

thanks for the help, been flying for over 32 yrs now, just a small problem with this one plane

JohnBuckner

My Feedback: (1)

I have used a gyro on the rudder successfully on two of my eight current flying multi engine airplanes and the reason is uneven spoolups of the engines during a slow throttle up takeoffs preventing the takeoff waltz This is most important on the four and six engine airplanes. They certainly can help with certain problamatical airplanes.

The gyro is plugged to the rudder Rx port and the rudder servo(s) is plugged to the gyro. The gyro must be secured in the airplane with the marked axis on the case oriented vertically. The Gyro must be located fairly near the center of gravity. Having a shutoff feature on a spare channel is not neccessary. The gyro set properly will not affect your normal pilot imputs or the flight of the airplane. If the gain is set too high the result will be a slight hunting in yaw during high speed flight, You simply slow down, land and adjust the gain down.

It is tested each morning by switching on the tx/rx and wiggling the tail of the airplane vigorusly and you will see the rudder make quick momentary imputs in the opposite direction of each wiggle.

The two I have are the hobbico airplane gyro (now discontinued) with a neutral adjustment and gain control. The gain is set around 50% to start with and the neutral should be checked each day before first flight since all piezo sensor units are affected by temperature changes.

John

Villa

Hi handyman
It looks like you and I started with R/C about the same time. I learned in 1972 and built an 8 channel single-stick Heath Kit radio to learn with. About 2 years ago I designed and built a SPAD J3-Cub, using the dimensions for a Sig 71" wing span J3-Cub as a guide. I had many of the same problems you described with it, plus even worse ones. I snap rolled it 2-3 times on takeoff. I had completely forgotten how to handle a J3-Cub. Fortunately, being a SPAD, there was actually little or no damage. One of the blessings of getting old is that I don't have to remember everything. Anyway, once I figured out how to take it off and fly it, I concentrated on getting the landings correct. On this thing, what appeared to be a good landing would end up with the plane going down on the nose and frequently ending up-side-down. I moved the CG, I even moved the wing, went to bigger tires; nothing worked. Finally I noticed that just before it would nose over, it rapidly went left-right-left then nose over. It could have been right-left-right. I could not seem to stop that motion with rudder input. I even tried some up elevator to get the rear tire to "grab". This was too dangerous because the plane wanted to takeoff. I just could not give up on this challenge. One day I wondered if a larger vertical stab would help. I re-checked the area of my vertical stab and it was to spec. I then added a piece of 2MM Coroplast to the front of the vertical stab that increased the vertical stab area (not the rudder) by 100%. I got rid of the last minute wiggle and resulting nose over. My CoroCub (the name I gave my Coroplast J3-Cub) probably has a wing with greater drag than the model I based it on. I believe my wing is thicker. Good luck with solving your problem.

morganflyboy

My Feedback: (14)

Hey Handyman, I just finished up a GP 40 size Cub last summer and I clipped the wings to 61 Inches and I am running a Magnum 70 F/S in it. I fly 4 different Cubs and I Noticed with the G.P. on take off, throttle managment was needed or it was all over the run way. What I mean by that is, Low Rate Rudder on take off and I do the throttle advancements in steps EX - idle to 1/4 throttle full elevator for tracking with rudder. 1/4 to 1/2 release elev and tail should rotate, still feeding in right rudder to keep it straight. 1/2 to 3/4 plane should be straight and ready to rotate from ground, gain about 50 feet of alt and advance to full throttle slowly. None of my other Cubs fly like The G.P. thats for sure, give it shot you nothing to loose. Good Luck

Morgan
As they say, nothing flys like a CUB!!!!!!!!!!!!!!!!!!!!!!!

madsenw

My Feedback: (5)

I talked to our resident expert and he feels it could be several issues. First, is it possible the wing is warped? Second, have you measure from main wing to elevator to ensure the wings are equadistant? Third the elevator may not match the datum line which will affect how it performs. Fourth, the part of the cabin where the wing attaches may be out of sink.

BarracudaHockey

My Feedback: (11)

John, excellent post. Let me correct one miss stated "must" though.

That doesnt matter a bit other than balance purposes. Mount the gyro where its flat to the yaw axis, and in the area of least vibration.

handyman

My Feedback: (2)

thanks guys i checked all that, after 30 yrs of flying thats a norm thing to check, even on a ARF, think i will go with the gyro, just need to find the rite one

JohnBuckner

My Feedback: (1)

In the case of the two I own the Hobbico airplane gyro the instructions do indeed suggest locating as near as pratical to the Vertical axis/CG. And I did find out it does make a difference in sensitivity if located in my case further aft. That was on my first one and I later moved it closer (forward) and its performance was improved.


On the matter of the gyros orientation I beleve we were both expressing the same thing in a different manner

Live Wire

After 60 years I say use common sense, and fly the sucker.

GaGeeBees

My Feedback: (23)

Before you drop $200 on a gyro, I strongly suggest you try using very low rates on the rudder for takeoff. I think you'll be amazed AND it won't cost you a cent Of course if your mind is made up, it's your model and it's your money. Go for it and good luck. Let us know how it works out.

Oh... and only six years experience here so of course I defer to all the more experienced advisors here.

landeck

My Feedback: (1)

The following is a great thread on using a gyro to control direction on take off using the Futaba GY401 gyro.

http://www.rcuniverse.com/forum/m_60...tm.htm#6056543

Bruce

David Bathe

I have the same model, clipped.
Toe-in is a no brainer... just do it, then...
SLOW and VERY EASY on the throttle.
Id you're anything past one third throttle at the end of the take of run... you've over cooked it.
It's literally one click of throttle at a time... slowly let the plane advance... and use VERY little rudder etc etc.
Taking a Cub of with finesse is one of the great RC challenges.
99% of the time ours are massively overpowered in a scale sence... the plane needs to fly on the wing.[8D]
Get into the minimal engine mind set and enter a Zen like sense of tranquility.[sm=sleeping.gif]
Enjoy