I'm trying to learn to spin my Gp Ultimate and am not having a great deal of success. My approach has been to reduce airspeed and then as it stalls slam the stick back and add full rudder. I get a nose-down corkscrew. When power is added the corkscrew tightens but doesn't flatten at all. I have even tried reverse aileron to level the wing and flatten the spin, but the aileron overpowers the rudder and the plane just crabs out of the spiral. I think I'm close, but I'm not sure how to get it to work. The CG is per the plans and throws are more or less as suggested in the manual. I have added a little elevator throw to get a better snap. I'm wondering if I need more rudder. I suppose moving the CG aft would help too. It's already a little pitch sensitive, though, and I don't want to change the CG if I can help it.

Since I'm here I also have two other questions which might also relate to spinning. The plane tends to tuck under in knife edge and has a lot of rudder/aileron coupling. I can handle it, but is there anything I can do to "tune" this out. The plane also has a slight tendency to climb inverted with no forward stick. Any recommendations on that? Overall, the plane is an excellent flyer. I just want to know if there is any "tweaking" I can do to bring it in a little more.

I learned to spin a full scale Cub by accident. My instructor had me in a steep climbing turn stall. When it stalled, I gave it opposite rudder, I thought. But I gave it rudder to promote the spin. I'm not an expert in RC, but have been able to make my planes spin by putting them into the same climbing turn stall, and holding full aileron and rudder. They spin. Every plane I've had recovered when the controls were neutralized. Maybe someone more expert can comment on the besttechniques. I'd like to know the procedure for inverted spins.

Try full left aileron, full left rudder, full up elevator at slow speed. That should develop a spin.

If it doesn't, try full down elevator, full left rudder, rull right aileron. That should develop an inverted spin.

Check your wing incidences. I wonder if one wing is stalling well before the other, caseing the plane to just drop the nose and regain flying speed rather than snapping or spinning.

follow Montague's advice for entering a spin. But from the original post it sounds like your trying to do a flat spin. The way I enter a flat spin is to start with a normal spin and move the ailerons to the opposite direction and add power.

However, not all planes want to flat spin, and often you have to adjust the amount of aileron, rudder and power to get a nice flat spin.

... and the CG. Some models won't do a true spin with the CG in the usual location. Also it can help if the vertical fin/rudder area is on the small side of stable. Don't go TOO far on all this or the model will become very pro spin and a bag o' bits will be the result.

The absolute worst model I ever flew for this pro spin charactaristic WAS (yep, bag o' bits time on third flight) an ARF Piper Cub. The model looked good to the naked eye but something was seriously wrong with that design. It finally crashed despite adding washout, moving the CG forward and deliberatley trying to avoid slow flight. A model from hell.....

Needs more elevator.

A true spin requires the inside wing to be stalled while the outside wing is still flying. Since a stall occurs with too much angle of attack and the elevator controls the angle of attack, the amount of elevator throw controls whether a plane will spin or not.

Dan

... or you could just drink a few shots of tequila- that usually gets things spinning pretty good. [sm=bananahead.gif]

sorry, couldn't resist.


Anyway, I agree with Dan, you probably need more elevator to stall the inside wing.

One thing to note guys, the origional question was about a biplane. If it was a monoplane, I'd totally agree, more elevator and/or move the CG back. It can't hurt here either, but it sounds like you might be rather far back on the CG already. On a bi-plane, if the wings are way out of alignment with each other, you could make it very hard to spin it well.

Oops, thanks, Kirk- missed that.

If a biplane, then there might be an issue with wing incidences. You should make sure that they are set correctly (and I'm sorry I don't know what that is).

A couple books written by full size aerobatic pilots state that a spin is a Rudder-Elevator manuever. Most planes should not need ailerons to do it. In fact, they say that with some planes, the ailerons are ineffective, because by the time the plane actually properly enters the spin, the wing is stalled to the point the ailerons don't have an effect. Of course, that is probably because a correct spin is entered from a full stall.

Hi ksechler

Having come to R/C after having spun many full size types IRL, quite to my surprise in my early attempts I discovered an universal anomoly occurs when attempting to spin an R/C model vs the real McCoy. Classic full size spin entry will only result in a spiral dive developing for a your typical R/C model...which is precisely what you are experiencing.

The following spin entry techique pretty much works for any R/C model which will stall and has the CogG located sufficiently aft such that it will spin. Non-dynamic stall spin entry described.

Select an entry heading and reduce power to flight idle. Smoothly increase back stick (elevator) as speed bleeds off raising the nose to maintain original height. At the point of stall smoothly apply full back stick simultaneously with full rudder in the intended direction of the spin plus apply full aileron in the direction of the intended spin. Yes, full in-spin aileron! The model will incipient spin. To stabilise and maintain the spin, just hold the controls there and count off the rotations until you want to exit. Nose attitude and rate of rotation are dependent upon the individual model & type.

Recovery with an exit on line requires anticipation (¼ turn lead at most), but generally all that is required with any R/C model I've flown is simply to centralise the controls, wait until the rotation stops (quasi-instantaneous with R/C models), recover the nose to the horizon with elevator whilst maintaining wings level with aileron and line (heading/track) with rudder, smoothly apply power and fly away. Quite different, even with idiosyncratic type variation, from full size IRL.

The requirement of application of aileron in the direction of spin to initiate and to maintain same is the anomoly. I've not yet found an R/C model which will initiate a true incipient spin without it. Suggest that you go with engine torque & initially initiate left hand spin entries until you're comfortable with spinning and recovery.

As you've discovered, if you apply positive outspin aileron at the point of entry, instead of initiating a wing drop and assisting spin entry or inciting a dynamic entry as as it frequently does IRL, it denies spin entry in an R/C model completely. Neutral aileron (non-application) in a spinnable R/C model simply results in it entering a spiral dive.

There are models that will spin with just rudder and elevator. The easiest way to get one is to take any acrobatic model that spins well with the ailerons and add a few pounds of lead on the CG. It's amazing how much better they spin with the higher wingloading. One guy at my club had a trainer that would do some of the best looking flatspins you've ever seen. After he bolted 4lbs of lead to the bottom of the fuse. With out the weight it wouldn't spin, with it, he could do a flatspin landing that wouldn't even break the prop. It was quite impressive.

You'll also discover that higher wingloadings also result in a much longer delay in getting out of the spin. I've seen models do an entire rotation after the sticks were centered before recovering. I've also seen models that would not recover with out opposite rudder, down elevator and/or other full-scale type control imputs.

My old overweight (6.5lbs) Cap 21 .40 size would do a very pretty spin with elevator only, no rudder, no aileron. Just slow it down and hold the nose level with more more elevator. Eventually the nose would drop and one wing or the other would drop and you'd spin. That plane took about 3/4 rotation to get out of a spin, and an extended vertical dive after the spin to get enough airspeed back to make a safe pull out. It also snaprolled in a blur, almost impossible to get a clean single snaproll, but double snaprolls were really easy. To get a slower snap, I'd just snap it with low-rate elevator and just a touch of rudder only. If I went at all on the ailerons, or much rudder, it would really speed up the snap.

To further confuse things, I also fly combat planes that don't have rudders. I can spin them with just elevator and aileron. And yes, it's a true spin, not a spiral dive. The nose is 45* down at most, and I can even flatten the spin by taking out some aileron after the spin starts. Of course, these planes have LOTS of elevator LOTS of aileron, and rather far back CG's.

One of the wildest spinning planes I ever had was a Duraplane with a Fox 25. Enter the spin from a full stall, full rudder and up elevator, get the spin started, then go to full down elevator. Found out quickly I had to increase the engine speed from idle or it would shut down from fuel starvation. Without any fuselage side area behind the wing however meant I had to start recovery above 75' altitude. It took about 2 turns to come out of a conventonal spin and 3 to 3 1/2 to leave the flat spin that developed with down elevator.

Are you trying to ENTER a normal spin, or a flat spin, or just trying to spin?
If your "nose-down corkscrew" is not a spin, are you adding power to enter a flat spin?

The correct way to ENTER a spin is to go to a 30 degree nose up, wings level attitude, and reduce throttle to idle while maintaining that attitude until the airplane stalls; at which time add full rudder while holding the stick full back.
If your airplane does'nt spin after the first half turn, or won't spin at all, then you need to add more rudder and/or elevator throw to insure that the airplane remains in a stall. A spin is a full stall maneuver!
Adding power is part of a flat spin recovery, but not ordinarly used in normal spin recovery.

feihu

A plane no longer made by Balsa USA was the Super Stick for a 60. This had a swept back rudder and fin. It was east to get into a spin and recover but a flat spin was a true adventure. Once in you couldnt recover, we tried 6 different models and the results were the same.
If into the spin we increased power and the rotation increased and suprisingly we would land about 40% of the time with the motor running and take off. Other times it was straighten out the gear and go fly again.
This was again demonstrated when the first hershey bar funfly models appeared and full power flat spins were accomplished.

Dennis

I think the Balsa SA Swizzle stick series was based on a construction article in RCM. The concept was a simple fuselage that could be built around any spare wing you happened to have laying around. I built one for a 15 using an old live wire trainer wing. They could be a bear to take off grass. They were spinning fools, al right. I think RCM still sells the plans. Tey go together quick, if you have an available wing.