down thrust Guillow's Arrow

[icedriller]

I am building a Guillow's Arrow and following the instruction for powering it with a .020 Pee Wee.The instructions specify 3 washers behind the motor on the upper two bolts for down thrust.But.....it does not give the size of the washers, thin or thick. My washers stacked 3 come to 1/8". Is this too much or too little

[HatzLymanC]

I had an .020 powerwd one many moons ago.  1/8" will be a good starting point.

Lyman

[Pit]

The washers the instructions refer to are prolly for 2-56 screws.  The thickness of the ones I still have is 0.018".

For what it's worth.

Pete

[gossie]

Your better off building some downthrust into the firewall rather than using washers if it's not too late.

[icedriller]

   Thank you for the suggestion. Nope not too late. How much would you suggest?  1/8"

[gossie]

   Thank you for the suggestion. Nope not too late. How much would you suggest?  1/8"

Can't say I know the model, but if it's Pee Wee powered I guess it's about 30 to 36in span?
  I should think 1/8th would be about right as a starter.  But you must remember EXACTLY how much downthrust or sidethrust too, for that matter depends on a lot of things.
Start off with the 1/8th or a fraction less and see how it goes, then add washers where ever if need be.
Good luck.

[squirlye]

Hey icedriller keep us updated with your Arrow.  I bought a Arrow last month. And I am either going to go RC or free flight with mine. But I recently discovered a cox .020 in a box of msc. 1/2 A engines. So now I think I want go with free flight. Nothing like someone else doing R&D lol....

[Konrad]

Ice,
I don't have a set of Arrow plans with me but I've attached what Guillow shows is needed for the smaller Javelin 24"  Kit #603.
Please note the ridicules amount of down thrust these needed with the 0.020 FF (Note the 3/16 shorter bottom dimension). I would also recommend using a prop with the airfoil backwards for the first trim flights. I will tell you that when trimmed correctly the Arrow climbs like a home sick FAI Angel. If doing the 0.020 conversion please make the wing spars out of bass wood and maybe add some more spars. We don't want the wing going into fluter.

All the best,
Konrad