Severe problem with snaping out of loops. Aeroworks 260 .60/.90

[STANG KILLA SS]

I have put several more flights on my 260. Flys really great till you pull back with the elevator. Wants to drop the right wing and roll over on its back BAD. just rolls right out of the loops. Does it on low rates as well as high rates. If you just ease into the elevator and fly low rates using 1/4 of the stick movement in seems OK and flyable. But if you make a sudden move it snaps or use more than half the stick movement it rolls hard out of the loop. usually only getting half a loop and rolls back upright at the top. and on high rates its pretty violent.
weve tripled checked were not getting a mix and not accidently putting in aileron input.
I found a heavy wing tip, balanced, and thought that might fix it. No good. Put some up aileron in it and no good. Added nose weight,no good. Added tail weight,no good. It flys so good other wise, the Saito 100 is a great match for this plane. With a 16x4W it performs really great. The strange part is if you roll inverted and go full down elevator it seems to be OK. The travel is the same for both up and down elevator.
throws and CG are dead on aeroworks recomendations.
any one ever had a plane do this? roll hard when on the elevator more than half way?

[kamikaze89]

That is an issue with the CG it sounds like. Maybe try to move it even farther forward and see if that helps? Does it have any other tail heavy characteristics?


Chase

[jtec/radiowave]

If everything else checks out it sounds like you have too much elevator throw. back down on your rates and when you pull use less elevator. My guess is that if you did a sudden pull on a stright line run it would snap also.

[JBenson]

I just helped a friend maiden his AW 60-90 260 this past Friday and it did not diplay anything like this. I did several hard pulls trying to get it to snap and it wouldn't. You might want to make sure both servos are traveling equally. Below is the video of the maiden.

YouTube - Danny's Aeroworks Extra 260 .60 - .90 -...

JB

[bodywerks]

If you pull enough elevator on any aerobatic plane it can do this. However, to help prevent it from doing it you need to make sure you have a perfect lateral balance and that your elevator halves are traveling the exact same amount through the entire range of travel. I believe the 60-90 260 has a mechanically linked elevator so there is only so much you can do there, but I am not surprised that it is breaking out to the right, given that it is a side-mounted engine. Take your battery pack and mount it to the left side of the fuse and add about 1/4 ounce to the left wing tip and fly it again.
if it stops doing it then great. If it doesn't, then get some altitude, point the nose straight down at idle, gain some speed, and swiftly pull back on the elevator(low rates) and look to see if the plan recovers to level flight with the wings level. You obviously have to make sure you are not inputting any aileron or eleator when you do this. Which ever wing is low is the heavy wing.

[jtec/radiowave]

your best source of info is Aeroworks. Give Rocco a call I am sure he can help you out

[STANG KILLA SS]

	Quote: Originally Posted by kamikaze89
	That is an issue with the CG it sounds like. Maybe try to move it even farther forward and see if that helps? Does it have any other tail heavy characteristics? Chase

were almost positive its not tail heavy. no touchy elev or porposing. and tracks like a pattern ship. and when you go inverted, it sinks downward. we actually thought it was quite nose heavy, even though on a full tank the CG is dead on aeroworks marks. we added a ounce to the tail and it didnt help.

[STANG KILLA SS]

	Quote: Originally Posted by jtec/radiowave
	If everything else checks out it sounds like you have too much elevator throw. back down on your rates and when you pull use less elevator. My guess is that if you did a sudden pull on a stright line run it would snap also.

but it does it on low rates with 1/2" of travel. thats not the problem.

[STANG KILLA SS]

	Quote: Originally Posted by bodywerks
	If you pull enough elevator on any aerobatic plane it can do this. However, to help prevent it from doing it you need to make sure you have a perfect lateral balance and that your elevator halves are traveling the exact same amount through the entire range of travel. I believe the 60-90 260 has a mechanically linked elevator so there is only so much you can do there, but I am not surprised that it is breaking out to the right, given that it is a side-mounted engine. Take your battery pack and mount it to the left side of the fuse and add about 1/4 ounce to the left wing tip and fly it again. if it stops doing it then great. If it doesn't, then get some altitude, point the nose straight down at idle, gain some speed, and swiftly pull back on the elevator(low rates) and look to see if the plan recovers to level flight with the wings level. You obviously have to make sure you are not inputting any aileron or eleator when you do this. Which ever wing is low is the heavy wing.

we have balanced the plane, it was severerely right wing heavy, we had to add 1 oz to the left wing tip to get it balanced perfect. it didnt change anything still does it just as bad.

its a single elevator servo plane, ie the elevators are one piece, so thats not the probem.

weve tried that test . and trying to pull out the plane would do a half roll. after 4-5 of these we were out of safetly altitude and she went in the trees.



a simple repair and we had her back up. checked CG and balance and put back in the air, and it still does it.

yes we have made absolutly certain we are not putting in any cross (aleron) inputs.

[Tired Old Man]

A lot of different factors control how a plane flies, including pilot input.

Center of gravity has a trememdous impact on snapping. Too far forward, regardless of what a manual states it should start out at, can cause a snappy plane. Most manufacturer suggested c/g's are set pretty forward to make a plane fairly safe for everybody, newbie and experienced alike. The owner always has to take the time to learn the plane and adjust the c.g to the personal flying style and desirable traits.

Airspeed can be a problem. Too slow and too much control input and a plane stalls. Too much control input can generate a stall at any airspeed, so keep that in mind when you pull full deflections.

Aircraft weight has an impact on performance. One can make a plane too heavy for the available wing area, requiring that the plane be flown much faster than usual to keep it in the air.

Lateral balance has an effect, but it's relatively minor compared to control deflection/input and c/g.

Typically, the problem with a plane being snappy is one generated by the owner. It may be due to a lack of understanding of aerodynamics, not understanding set up and trimming, or just simple over controlling. Either way the owner needs to take the time to learn what a plane does and adjust the various factors that cause a plane to snap. There aren't very many planes on the market anymore that have flight control problems out of the box, and virtually none of them will be ones from the major name shops.

[STANG KILLA SS]

great info. i still thought it was a CG issue. too nose heavy, but the 1 oz on the tail didnt do anything. maybe it needs more.
we were flying at 1/2 to 3/4 throttle for the tests.
great post. i think well concintrate on CG for our next test.

[kevod]

I read that you checked the deflection of the elevator on the ground, but is it possible that part of the elevator is flexing in flight due to a weak linkage, weak wood in the elevator, blowback, so on?

I had an airplane a long time ago that had the exact same tendencies - it would snap out of up elevator pulls but down elevator worked fine.
I ended up putting carbon fiber over the push rod as it was fairly long and it never had that problem again.

[bodywerks]

What are yor low rates, how many degrees? Are you trying to do like a hot-dogging loop or a precision, circular loop?
You could also just be too heavy and will just have to fly the plane more carefully or lighten it up.

[The_Wreck]

I have had this problem on planes before, and in two cases it was do to wing warping or an incidence issue between the two wings. If it is incidence, you probably will need to carry a lot of aileron trim to get level flight, If not it maybe warped wings. If it is almost always snapping to the same wing, upright, but then is ok inverted, I think your wing maybe warped. The leading edge at the tip warping up will cause the wing to stall faster, the leading edge down at the tip will cause it to stall later.

You can use an incidence meter to check the wing at the root and the tip to test if it is warped. On a lot of smaller arfs, you can twist the wing by hand and tighten the wrinkles created in the covering to get it back into shape.

[Tired Old Man]

The C/G is generally considered correct when you can fly the plane at a medium upright airspeed and have zero elevator trim required to maintain level flight. Any trim input equates to a weight imbalance at one end or the other. Rudder and aileron trims should be neutral for straight and level flight. Any trim inputs work the opposite direction when a plane is inverted, so you really don't want to have surface trims controlling straight and level flight.

From that point you can work on engine thrust lines using simple throttle inputs in level flight to determine if thrust changes are taking place with throttle ups or downs. If you have a pitch change with throttle changes then you adjust the engine thrust angle or, when changing thrust angle is impossible for whatever reason, develop a throttle to elevator mix to compensate.

Once those are done yopu start working on adjusting the control throws needed to obtain the ability to make a full elevator pull at a given airspeed. The "book" values will generally need to be adjusted downwards to some extent to achieve a full pull without a stall at a constant medium airspeed. Don't forget that we're talking about IMAC type flying here where one is tryng for constant airspeed flight in all orientations. 3D changes all that dramatically.

Once all the above is complete you can start working on mixes to offset any undesirable coupling that may take place with various control inputs.

As you can see, what comes out of the box is not perfect for every flight condition. Trimming is an involved process that requires many flights, lot's of time, and considerable thought before a plane flies as well as it could or should. There are far too many user induced factors that have an effect on trim conditions when a plane is assembled, so the manufacturers can only provide generalized set up information to get a plane in the air. After that it's completely up to the individual to determine what kind of performance they have and that performance is controlled by trimming the plane.

You can't work on only one item to correct a flight issue. There are many other areas that add input to the issue so you need to understand what makes things tick and move forward accordingly.