Wing setup advice

[Boots]

I have a non programmable tx hitec focus 6.

I have a  FMK Flutterbug, I built another wing for it with ailerons. the new wing has an identical aerofoil section and same wing area, the ailerons are almost entire wing length, wing cord 15cm . aileron cord 2.5cm.

flutterbug wing is flat  with dihedral on the tips whereas my wing is a std centre dihedral type.

I have 5 degrees dihedral and 6mm up and down on ailerons.

After having crashed I am sure I need less movement on aileron.

 

I am not a skilled pilot so I am looking for stability  not aerobatics

 

questions

should I increase dihedral  to say 10 degrees ?

what ratio of differential should i use , 70% down and 30% up ?

[Former Member]

[This posting has been removed]

[Boots]

 Eric

        the FMK  flutterbug is a 3ch , speed 400   powered glider or light plane, quite a low wing loading, 15oz/ 420gm all up weight with a wing area of 241sq in/ 1550 sq cm.

 

on 3ch, rudder and elevator it flys very well. even for me!!

with new wing ,as always cog was between 25to 33% of wing cord, I have been advised to always err on the slightly nose heavy , never fly tail heavy.

I took off and trimmed ailerons for level wings, then i flew rudder elevator only 

elevator control seemed normal

rudder control seemed much different,,,,,after a normal turn wings would not level, had to use ailerons to do this.

I tried to fly aileron elevator only but could level out and straight out  after a turn either  at this point things all went wrong

 

I think the crash occured due to too much aileron causing  the plane to stand on its wing tip and bank heavily after which a tight corkscrew into the ground. once I have a plane into a difficult position I react too slowly and half the time seem to give the wrong control too .

 

 

I have been advised to adjust ailerons for more down than up? 

 

             

[Delta Whiskey]

For my wing, with no rudder, I had to use evelon mixing, are you sure you can use the non programmable tx with it?

[Simon Chaddock]

Boots

My guess is that by adding such large ailerons on a basic rudder/elevator design probably means you won't be able to fly it easily as rudder only.

 

Remember the rudder makes the plane yaw and it will only yaw so much as the fixed fin prevents it going too far. Once the plane is yawing its built in stability induces a banked turn. With the rudder back at neutral its natural stability returns the wing level.

The Flutterbug is a trainer so the rudder is relatively small to ensure any manoeuvres do not get out of hand too quickly.

 

However the aileron is a primary control. It makes the plane roll and it will continue to do so until you do something about, it by which time the plane could be in a position that it might not easily recover by itself - as you found.

 

So the question is does your new wing have the same natural stability as the old one? From your description it sounds like it does not, so some aileron control is required, but the emphasis is on some.

 

For a trainer my advice is either to significantly reduce the aileron movement or better still make them smaller, spanning no more than the outer one third of the wing. This should reduce the rate of roll to something you can safely manage.

Well that my 2d worth I hope it helps.

Edited By Simon Chaddock on 19/09/2009 01:29:55

[Former Member]

[This posting has been removed]

[Pete Robinson]

Posted by Boots on 14/09/2009 08:08:44:

I have a non programmable tx hitec focus 6.

I have a  FMK Flutterbug, .........................

 

I am not a skilled pilot so I am looking for stability  not aerobatics

 

Hi

 

I have been out of the hobby for about ten years and getting back now.

 

I built the same model but had big problems getting it stable. Mine has a 1000KV motor and lipo cells. It is fine now that I have added 3/32 packing under the leading edge and a tiny amount of downthrust to the motor.

 

The plan shows no incidence on the wing or tailplane at all. I.E. everything set to neutral like an aerobatic model.

Surely in a model like this (powered glider) there has to be at least some incidence.

 

Well she flys perfectly now and very slow as it is very light with a battery the size of a match box..

 

It used to climb well under power and with power off would streak to the ground.

Its good to know that someone had luck with this model as supplied.

 

Was this one of the new laser cut versions of the kit?

 

 

Peter

 

[Boots]

My Flutterbug was built by copying another one which is 8 years old, I have no plans.

my wings seem to have only half the dihedral it should have.

I broke my speed 400's by smashing them into the ground so I now use an emax 2812 outrunner 7 x 6 slow fly prop and turnigy 1300mah 3cell.

I have appx 4 degrees down and side thrust

 nose is too short so the former in the fusilage  under the front of wing has been removed to allow the lipo to sit under the c of g  

the rx and servos are as far back as they will go ( below trailing edge)

towerpro 30a esc in nose

motor draws 16amp full power so it is some 190 watts , static test 800 grm thrust and flying weight 600 grm

I am sure it is now over powered, shame !! will climb very quickly at 40 to 50 degrees which means its too small to see very quickly. it cant sustain vertical flight so i guess in flight thrust is less than 600 grm

I suspect my static thrust rig is no good

A friend who can fly anything has done alsorts of aerobatic stuff with it

Best plane I have ever had

looks like Peter went for the sensible settup and I chose hooligan.

 

[Pete Robinson]

Well mine clims at about 45 degrees and runs a 9x4.3 slowfly prob.

Flown slowly it looks just like an old style rubber power model.

 

I changed the construction quite a bit as the kit is pretty basic. I added formers to the rear and made a hatch on the nose secured by magnet.

I put a steel straight edge under the wind and measure the distance of leading and trailing edge of the tailplane. That is when I discovered there was no incidence at all and the plan was just the same.  From my FF days I know that a lifting wing needs some incidence. at least. Hence the rush to the ground when the motor was cut. only loads of up ele solved the problem.

 

I have a 1000 KV motor and two cell 900 lipo.

 

Even with this setup it can be well away from you in no time at all.

Electric power has opened up a new world for me because I can turn off when things go wrong and turn on again too............great.

unlike the diesel powered rudder and ele models I have built and flown in the past

 

Your model

I think folk here are right about much shorter aelerons and less movement.

One thing I do know is that small models respond to tiny changes in trim. Unlike the 80 inch FF. gliders I flew when I were but a kid. and my recent gas powered 60 inch Junior 60.

 

To trim and fly a tiny model takes a great amount of skill and I take my hat off the those who can do this.

 

Pete