I have a Kyosho agwagon. It is fairly aerobatic, but in certain manuevers, most Im using rudder,it trys to flat spin coming out of it. Now i know that a real agwagon put into a flat spin will never come out of it. Mine has mod wing tips that are pointed up, kinda a small verticle wing. Does anyone have a idea to why it wants to do this death manuever? Is there a way to stop it?
My theory---At the end of the stunt, the plane stalls , when im using rudder, it trys to flat spin. I have enough engine to pull it out, but it has almost not made it several times.

If you are slow and in uncoordinated flight then there is a good chance for a stall/spin. The spin would then flatten due to an aft CG and/or lots of elevator throw. Moving the CG forward may help some, as well as maintaining enough speed through your maneuvers to prevent uncoordinated stalls.

My agwagon has lots of elevator throw, and is major nose heavy.
Im running a .70 OS 4 stroker on my agwagon, i got the power, but it seems on a exit, heading at the ground, it will spin a few times, and scare the crap out of me. AAAAHHHHHHH.lol.
thanks for the info falcon.

If it is truely "major nose heavy" that's as bad or worse than tail heavy. A very nose heavy aircraft will stall/snap/spin in a heartbeat, particularly when using lots of elevator out of a dive. Tied to very large elevator throw it's no wonder the airplane is scaring you. A nose heavy aircraft situation works the wing the hardest because it has to generate more angle of attack to fly the airplane, leaving little left over for maneuvers.

A tail heavy airplane works the wing the easiest but it also causes pitch up's which lead to stalls and maybe spins. An aft Cg is the usual cause of a true flat spin (rotating in yaw with fuselage parallel to the ground). Power (with recovery controls) is the only thing that will get you out of a flat spin.

Recommendation: remeasure the Cg and get it to 25-30% of the MAC.

Dago:

When the P-80 (F-80) was developed into the T-33 it had a bad characteristic: control departure often put you in the grip of what was called "TheThing." Guess what.

On the T-bird this was solved by adding empennage area. Logic tells me it was added to the vertical fin, but memory says it was added to the horizontal stab.

but on a small plane it's eay to try, and hurts nothing.

Cut a triangle of medium balsa, fit it to the front of the vert fin, make it look like a P-51d. Stick it on with Shoo-Goo or something else that will come off when you want it to. Fly it. Improvement? Make one a little bit larger and try again. When you stop getting improvement, do the same triangle trick to the stab. You will find a combination that will work fine. Might take several tries.

When it flies as you want it, then make nice parts to go where your temporary ones were, glue them in properly and paint/cover them. Fly happily.

Twin caught in "The Thing? Either get out, or "Ka-Ching!

Bill.

im not sure what u mean William Robison, but is this what you mean on the vert stab? Like the stang. The agwagon has few caracteristics like the stang to start out with, so i might all ready have them on the plane.
My next option its to throw some weight into the tail to balance it.
thanks for the info.

this is the most recent picture of my agwagon. I had a 4 blade on it, sounded and flew great. now im back to a 13-6. I had to put quite a bit of off thrust on to engine, it torqued over on almost every take off, now I dont have a bit of problems with that.

Those little tiplets of yours are awfully far forward in the wing. Perhaps these are creating a de-stabilizing force that's competing with the vertical fin and rudder. My advice would be to rip them puppies off and see how the model flies without them.

Are they scale? I can't imagine them being shaped like that for full size. They don't look like the usual NASA winglets at all. For starters the ends of the ailerons are exposed. Certainly they would make lousy end plates for controlling tip vortices with then being so short at the rear. Perhaps this is what is causing the nasty tip stall, the vortix is sneaking around the ends of the ailerons and doesn't want to let go until you power out of the spin.

And I think what Will is reffering to is often called a dorsal fin or dorsal gusset. It's the short ridge running along the upper fuselage from the base of the more normal fin, ie: the bit they added when they went from the B model to the D model. Actually you've already got it.

I thought I had that little gusset.
The tips arnt scale, I made them after I cartwheeled the plane, destroied the scale wing tips--the cost of the wing tips are i think $30 a pair. The original curve down, hard to make.
I want to have wing tips on it, but what other kind of wing tips can I put on it to make a better flying plane, do I need to make them longer?
To tell you the truth, after I put these on , the plane turned better and didnt fall in a turn, as if acting as wings.
Do you know any NASA wing tips I can put on this puppy, that look good, make it fly better, and fairly easy to make, consider it took 2 hours to make the ones on it right now.

you can see the original tips are nothing like my mod tips.

Bruce:

Seeing his picture I agree 100% on his wing tip destabilizers. Rip off what you have there, Dago, and replace them with flat plates extending from the LE to the trailing edge of the ailerons. Make then exrend no more than 1/4" to 3/8" above and below the wing. I think you'd probably be better off with nothing than what you have.

And Bruce, "Right again, Robin," it's the fin gusset I was talking about. If the correction of the tip abomination doesn't take care of the problem, add the gussets to the stab. With those instability generators off the tips shouldn't need anything else.

A twin with those fences, rather lose my senses.

Bill.

PS: Dago, the original are called "Hoerner" tips,wr

Hum, this was simple, I think we solved my spin problem in one day, since I dont have time to build them tonight, ill build them tommarow and try them tuesday or next saturday. Ill report the results for ya'll.
Now for a second question, why is it that this plane can not recover from the a flat spin (death spin)? I think it is because of the high amount of dihedral this plane has.
Another mod I made to this plane is build a tailcone that is about 1/4" longer than the stock, not much, but it looks better, does that tail cone being lengthand have any thing to do with its flight caracteristics? I heard on the real agwagon, if you dont have that tail cone, its not safe to fly.
I think as you guys can tell, this agwagon is not a stock kyosho agwagon.

The small rudder certainly won't help getting out of a flat spin.

the rudder on this plane isnt that small? Do you mean the vertical stab, or the moving rudder. Sorry if i sound , well, the way i put thing isnt all that smart sounding. do i need to extend it ,kinda like a cap 232 rudder?lol.

Dago:

What Ryan is talking about is exactly what I said to start with, in different words.

If replacing the vortex generators with plain tip plates doesn't remove the tendency to flat spin, increase the size of the dorsal gusset until you have no further improvement, then if there's still a problem do the same to the stab.

Yes, if you would rather, you could increase the rudder area. The gusset is easier. More rudder area might work better, though.

Flat spin recovery requires the tail plane to be outside the air disturbed by the wing. That's why you can power out with a prop plane, the propwash blows the tail "Free" of the vortices, but low to medium power jets have to be knocked out with flaps, dropping the gear, or anything that can radically alter the airflow. A high power jet sometimes can be blasted out with thrust.

Twin in a flat spin? Wait, see how far it'll dig in.

Bill.

Later Tiger moths had dorsal strakes on the front of the stab at the root to stop unrecoverable spins. If you got into an inverted flatspin with a Harvard you were told to bail out. Unrecoverable!

WR, the Hoerner wing tip is not downturned.

The Agwagon has A-10 style downturned wing tips.

York:

I am not the ultimate information source, I have been known to err.

But I will draw your attention to Cessna. The late 150 series is advertised as having "Hoerner" wing tips.

The wing tips on the late Cessna 150s curve down.

Maybe "Hoerner" has to do with the vortices generated rather than a particular curve?

Twins with Hoerner, are for a fast burner.

Bill.

I've also seen these identified many times as reversed Hoerner tips way before the A-10 used them. The Maule Rocket used this type of downturned tips for one.

Ok, last night I added 4-5 inch monster truck wheels to the agwagon. our field is wet, and muddy right now. On the test flight every thing went on. I did all the normal manuvers that sometimes had the begining of a flat spin after. I never had it try to flat spin, but I did stall it, and it was tip stalling side to side while falling.
Could these monster tires have stoped the the flat spin episode?
Im going to remover the wingtips this week and build the flat plate wing tip for it.
Perfect flying day, my biggest problem is the tire came off the rim on a landing, funniest thing Id ever seen.

ok guys here are the new wing tips, what do ya thin, painted with black and 18 karat gold paint.

Dago:

A little crude but should be more than good engough for a test. You can always round off the front corner.

A twin, said the owl, requires a second cowl.

Bill.

Ill probabaly leave the the way they are,Im running out of paint, Ill test the plane this weekend and let you know what happens.

Ummm, ...... this may be a silly questoin but why do you want tip plates instead of just a plain old sorta streamlined rounded tip?

Bruce:

Possibly at my suggestion. This way he has a lot of the advantages of the (reversed?) Hoerner tips, without the aggravation of carving them.

Keep at it, Dago. We're with you.

Rounded, drooped tip or a plate, I like twins, they all fly great.

Bill.