wonwinglo

RayS has sent me this-

Hi There!
I've just acquired what must be one of the last Flair Harvard kits in captivity. I like your suggestion of building washout on the wings. Others in my club had trouble with tip stall on the same model.
Perhaps you could help with a couple of questions for a comparative beginner like myself:
1. How much washout did you find necessary?
2. How did you build it in?
Many thanks,
Cheers,
RayS

Ray,if you want Harvard kits then let me know,regarding the essential washout proceed as follows-
Lay down the spars and ribs loosely,on the trailing edge near the tip place a half inch block of wood underneath with a piece of plastic sheet between,so that there is a very gradual progression of washout from the very end rib to the root rib,once happy flood the ribs/spars/trailing edge with thin cyno and allow to cure overnight,repeat the procedure for the other wing making sure the washout is exactly the same.
Once this is incorporated you will never drop a wing on landing,even at very slow speeds,I just love doing circuits in this aeroplane,she is a beauty.
For those unaware with what this washout is for,the tip usually stalls first with the impending wing drop,by incorporating the washout the root stalls out first with no adverse effects.
Flair had a knockout model with the Harvard kit.

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/

RayS

Many thanks for the info. I'll let you know how I get on.

Cheers,
RayS

Uncivil Serpent

Hi Gents,

Just for someone who's having a senior moment, and knows nothing about aircraft, can you explain in simple terms "washout"?

Many thanks

Chris

wonwinglo

***Sure Chris,when an aeroplane stalls ( ie when it reaches a particular angle of attack on the wings that it ceases to fly ) it will usually just drop a wing and sometimes spin into he ground,this precarious situation can be stopped quite simply by making the root of the wing ( ie the centre section portion ) stall first,the way this is done is by gradually introducing what is termed 'washout' into and along the wingtips,looking from the back of the wings at the trailing edge the wingtip has a 'reflex' upwards towards the tip,this has the effect of taking the stall away from the tip where it is not wanted,and introducing it to a more benign area,ie the wing root,so think about it,the angle increases on the wing so the stall strikes the root safely and not the tip.
A good example whereby designers use washout or reflex as it is sometimes referred to is on tailess or delta wing aircraft.
Trust that this answers the question so that you can understand the principles.

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/

Uncivil Serpent

Thanks Barry,

now a lot clearer than it was. Couldn't get the brain to remember everything I was taught in the ATC many moons ago.

Seasons greetings to all by the way

Chris

Uncivil Serpent

Thanks for that Barry, brain wouldn't recall lesson from ATC many moons ago.

Regards

Chris