H9 Extra 260 crashed after violent, uncontrollable tailspin.....

[Black Bird]

I do not believe it was a CG issue either. I flew my H9 Extra 260 hella tail heavy. At slow speeds, the tail would drop like a poopy dieaper. Spins were flat as a pan cake. The crash was pilot induced. The pilot put himself into a maneuver and did not know how to recover. The more tail heavy, the more maneuverable the plane. But, the pilot must account for the loss of controllability with the correct inputs.

Long story short, it was the pilot and not the plane. Keep practicing.

[RCFanatic12]

the wing tip is not the place to do it, this is copyed from the manual.

1-Measure back 5" from the leading edge at the root rib
and mark the location with a felt-tipped pen on the
bottom of the wing. This is the recommended center
of gravity (CG). The CG range for your Extra 260 is
between 4 3/4 and 5 1/4".
2-Fully assemble the model. With the airplane upright,
lift the airplane with your index fingers to find the
balance point. The balance point (CG) should be
at the mark made at the root rib. If not, add the
necessary weight to the nose or tail to obtain the
correct balance.
(updated wording for #1)-

Balancing the Model
Step 1 on page 40 of the manual
The first sentence should read "On both sides of the fuselage, measure back 5" from the leading edge at the fuselage and mark both places with a felt-tipped pen."

if you did it at the tips then it will most likely be off because the extra wing is tapered from root to tip in both thickness and from front to back.
that is another reason i use the string deal because its dead center of the front-back and side to side. but i know everybody has their own ways of doing it this is just the easyist way i have found to do it.

[/quote]

Yes, I measured from the leading edge at the root rib 5" back and marked it. I then followed that mark in a straight-line to the wing tips and balanced from that point. I couldn't think of any other way to do it since that's the only way I was taught. Are you supposed to measure back 5" underneath the wing, mark it, and then hold the airplane up in the air from underneath the wing at the mark next to the root rib?? I never quite understood the balancing instructions for the plane.

[RCFanatic12]

	Quote: Originally Posted by Black Bird
	I do not believe it was a CG issue either. I flew my H9 Extra 260 hella tail heavy. At slow speeds, the tail would drop like a poopy dieaper. Spins were flat as a pan cake. The crash was pilot induced. The pilot put himself into a maneuver and did not know how to recover. The more tail heavy, the more maneuverable the plane. But, the pilot must account for the loss of controllability with the correct inputs. Long story short, it was the pilot and not the plane. Keep practicing.

Ok, tell me this. How would going from a simply hammerhead maneuver into a straight downline with only minimal aileron input to start a tailspin cause my airplane to randomly enter an uncontrollable, tailspin/flat-spinning maneuver?? I had done smooth blenders with this airplane countless times before with 100% full aileron input and it remained completely under control. My actions as the pilot did not randomly cause these nasty tailspins to suddenly begin; minimal aileron input in a straight downline should not cause an airplane to spin out of control like it did, end of story. Yes, my inexperience in the situation and my incorrect inputs eventually caused the model to crash, but that's not the point of my thread. What caused the plane to enter the maneuver in the first place??

[Flatlandman]

maybe I missed it in this thread but what is your "tail spin"?

Is it possible that you had a lose bit of covering some were that could flap open and disturb air flow some were?

[RCFanatic12]

	Quote: Originally Posted by Flatlandman
	maybe I missed it in this thread but what is your "tail spin"? Is it possible that you had a lose bit of covering some were that could flap open and disturb air flow some were?

When the plane was in a straight downline and I'd input slight aileron to initiate a tailspin, the plane would violently enter the spin and begin tossing the tail of the airplane around uncontrollably in a semi-circular motion and would eventually begin an awkward flat-spinning rotation. And before somebody else brings up another CG issue, the plane flew straight as an arrow in pitch and it flew smooth as can be during slow, stall speed flight; the tail never wanted to drop and the plane never required excessive elevator input to level it out.

As far as the covering, I'd inspected the plane many times and I never noticed anything significant. One of the wing tips had some scarred up ultracote from a rough landing, but it wasn't like there was a bunch of loose covering hanging there.

[Flatlandman]

Have you checked the radio for a freak mix that shouldn't be their or a mix that has been altered?
The covering issue might be just a seem that wasn't completely down.

Also what was the weight of the plane?

[RCFanatic12]

	Quote: Originally Posted by Flatlandman
	Have you checked the radio for a freak mix that shouldn't be their or a mix that has been altered? The covering issue might be just a seem that wasn't completely down. Also what was the weight of the plane?

I had an aileron to rudder mix in the plane that I played around with last summer, but I never had my switch engaged and I definitely would've felt the mix during flight had the switch accidently been turned on. That was the first thing that crossed my mind when this originally started and I always made sure the mix was disabled before I took off. Is there any chance that it still could've been screwing up something in the radio??

As far as the covering, I'm pretty sure everything was securely attached; I wish I could examine it right now, but the plane's just a pile of balsa and torn monokote sitting in the trash can.

I weighed the plane just last month and it was about 14.2 lbs.

[SENEKAfive]

maybe your just a bad pilot just kidding, i think it was something sturtural.

[RTK]

I have never seen a plane go into a violent flat spin on a down line from just a small aileron input as you have stated, no matter where the CG was. I thinking it was something electronic causing this situation to occur when your plane was pointed down. Something grounding, etc that would cause the other servos to go hard over causing this violent flat spin.

[spoiler]

	Quote: Originally Posted by RCFanatic12
	There's only one addendum listed on Horizon's website and it's only related to an error in engine size recommendations. I'll call them in the morning to see if there's been a change that may not be on their website. Also, how exactly would I know if I had been having a binding problem. All of my servos seem to have been working just fine over the past few months and they all function properly after my range checks.

I somehow doubt it was your cg. I also have this plane and I balanced it as you did and since then have played around with the cg by moving the battery or using a heavier battery without ever measuring teh cg again. I was happy to do this as the plane exhibited no negative tendencies, just the usual things. The more rearward cg definately increased elevator sensitivity and made landings harder, but had no uncontrollable stability issues at all. How about some kind of airframe issue, like a bent wing tube...

[go29kev]

YES very much so it could have been a airframe issue... as most people know the h9 260 glue joints suck!!!!! my first one started to come apart in mid air. we got it almost back to the runway before it went in. in fact it was at joenall 2 years ago. when i got the plane back and started looking into what happend i found the glue was pulling off like a hard rubber. and all the joints was able to be pulled apart and the glue did not even pull any wood. It never bonded with the wood it was just stuck on a very thin part of the surface. and with my 2nd one i found the same thing but i knew what to look for and was able to pull the plane apart with one finger. i literly pulled the former apart by picking it up. so i reglued the entire body before ever flying. i have posted on this in another forum on fg and serville people have had the same problem. i love h9 but the cheep a** glue they use sucks.
it took serville flights on my first one before it happend so it could have been one of those that was week and just after some time finaly gave and the body could have started to come apart and caused the tail and wings to twist and that was the end...

[robertp17]

Ok heres my take. I too had the same plane and did not like it. It did weird things that I could not understand. Never found anything wrong but just was unstable as at times for no reason. Anyways for the balance issue, I balanced mine like it says in the manual and it kept showing a little nose heavy and then I tried it at the wingtips by making a strait line out the the tips and it was tail heavy everytime? Explain that one. Whats the proper way to check CG? Anyway it finally met an untimely demise at ATL huckfest last year when it broke in half as I pulled up into a wall. Cant say I miss it.