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View Full Version : Extra 260 mini crash! - copied from parkflyer forum


Buck Rogers
02-12-2008, 05:41 PM
I had originally put this in the park-flyer forum but maybe it is better posted here. I had an unfortunate incident at the weekend when maidening my Fliton Extra 260 mini.

It took to the air just fine but then when I tried to put in a turn things started to go wrong. I banked it over for a nice gentle turn and put on some elivator but not much seemed to happen. I then banked over a bit more - to about 45 degrees and put a bit more elivator on and it started to turn but not that fast. I put on even more elivator but still not much turn. I put on yet more elivator then it seemed to snap round very quickly so a backed off a bit.

In the end the turn was so wide that I hit a tree - not good and a fair amount of damage caused. Perhaps I should have been higher but I had already decided something was wrong and was trying to get back down.

Anyway, something definately seems to be wrong, I should have easily made the turn in the space I had and this is supposed to be a very manouvreable plane - the tree was quite far away.

Having checked everything out when I got home everything is still working - all control surfaces were fine. The question is what would cause this to happen?

My first suspicion is that maybe the COG is too far forward - at the time of the crash it was within limits but quite far forward. Possibly there could be something wrong with the thrust line but I think it looks ok.

Has anyone got any ideas on what might be going on here?

aviatordave
02-12-2008, 06:17 PM
Possible flex in the control linkage to the elevator?

or binding in the control linkage to the elevator.

Whats left of the fuse?

Murocflyer
02-12-2008, 06:31 PM
I'm not sure I understand what the elevator has to do with turning the plane. The elevator is used to raise the nose up and down. Do you mean rudder?

Thanks,

Frank

Buck Rogers
02-12-2008, 06:37 PM
Possible flex in the control linkage to the elevator?

or binding in the control linkage to the elevator.

Whats left of the fuse?

Its not too bad. The wing spar/tube has broken, the top of the rudder has snapped off and various parts of the fuse have taken some damage. Nothing that a bit of glue and new covering wont fix.

I checked out the control surfaces before flying, they all moved correctly and they still move correctly after the crash. There is a little bit of play in the elevator linkage but not too much.

The strange thing is that despite putting quite a lot of elevator on in the turn the nose did not seem to pitch up and the turn didn't seem to tighten up as it should have done. Thinking back I probably used a bit more elevator on take off than I expected too so I'm still thinking it could be a COG problem.


Murocflyer - since this plane has ailerons I was turning using the "bank and yank" method. i.e. bank the aircraft over and apply a bit of elevator to prevent side slip and loss of height.

aviatordave
02-13-2008, 01:43 AM
Yep, you need elevator when you use ailerons to turn, just like the RED BULL Racers :)

Lets ask this, what is the set up?

Start at the motor and work your way back, include everything....with brand names.

Possibly thinking you might have too weak of a servo for the elevator, let us know -

[and what the heck is Buck Rogers doing in the UK?....lol]

Angler-Hi
02-13-2008, 03:02 AM
Sorry to hear that Buck Rogers. I hope you get her fixed up.

Doesn't the elevator have a lot to do with a plane turning? When one of my planes are banking and I want a sharper turn, I give it up elevator to make that sharp turn. I love doing that, especially with my Cessna 182.

Anyway, I hope everything works out. Oh yeah, Frank, I don't have a lot of experience with using the rudder with ailerons at the same time. What are the flight characteristics of using rudder with ailerons/up elevator?

Mike

Murocflyer
02-13-2008, 03:07 AM
Murocflyer - since this plane has ailerons I was turning using the "bank and yank" method. i.e. bank the aircraft over and apply a bit of elevator to prevent side slip and loss of height.

OK, gotcha. That's sounds good then. It originally sounded like you were trying to roll using the elevator so I was confused. Totally my fault. Thanks for clarifying.

Glad to hear damage was not too bad. Can you take video of you flight control movements so we can help troubleshoot?

Thanks,

Frank

Murocflyer
02-13-2008, 03:09 AM
Sorry to hear that Buck Rogers. I hope you get her fixed up.

Doesn't the elevator have a lot to do with a plane turning? When one of my planes are banking and I want a sharper turn, I give it up elevator to make that sharp turn. I love doing that, especially with my Cessna 182.

Anyway, I hope everything works out. Oh yeah, Frank, I don't have a lot of experience with using the rudder with ailerons at the same time. What are the flight characteristics of using rudder with ailerons/up elevator?

Mike

Mike,

I got a great link that can explain all that and then some. I'll get back to you on that here in a little bit. Just don't want you to think I was ignoring you.

Frank

Angler-Hi
02-13-2008, 03:12 AM
Mike,

I got a great link that can explain all that and then some. I'll get back to you on that here in a little bit. Just don't want you to think I was ignoring you.

Frank

Hey thanks Frank! No problem.

Murocflyer
02-13-2008, 08:20 AM
Oh yeah, Frank, I don't have a lot of experience with using the rudder with ailerons at the same time. What are the flight characteristics of using rudder with ailerons/up elevator?

Mike

Mike,

The increased drag from ailerons actuation causes the plane's nose to drop. Adding some up elevator during the turn (roll) helps the plane stay level.

When you turn a plane using ailerons, the plane's nose tends to steer away from the direction of the turn so adding a little rudder toward the direction of the turn helps guide the plane around. (or so I have read -I cannot actually see this happening with my RC planes)

Both of these actions can be mixed into your flight controls with just about any good computer transmitter. Well at least I know my Optic 6 can do it and it was pretty cheap.

Here are some great links for reference. Which I always try to do so folks don't think I'm just talking ca-ca. So if you see me posting something without a reference link, feel free to call me out on it.


http://www.aerospaceweb.org/question/dynamics/q0045.shtml

http://www.av8n.com/how/htm/yaw.html#sec-roll-rudder

http://www.geistware.com/rcmodeling/articles/radio_terms.htm (you might recognize the author on this one)

Hope that helps,

Frank

aviatordave
02-14-2008, 03:30 AM
So Buck...any updates?

Buck Rogers
02-15-2008, 07:02 PM
I've been away with work the last few days so I wasn't able to reply.


Anyway, setup is as follows:

Motor - Turnigy 220 w motor (plenty of power) with 10x7 APC prop
SpeKtrum DX6 radio
4 x Spektrum s75 servos
Dual Sky 3s lipo

Set up for "sport rates" as per the manual with 30% expo on the ailerons and elivator.

I'm going to start repairs this weekend so I'll go over everything again to try and find the problem.