I have a Kyosho P-40 Warhawk with mechanical retracts. I am running an OS 61 FX and need to know what prop I should use. Please keep in mind that I would like to achieve top end.
I have not flown this plane yet so I have no idea what prop to use. I have an 11x7.5 on it now. Does this prop have too much pitch?
Please chime in on this one.
Thanks, Marco

i have several warbirds running 61fx.s. the best prop iv'e found is apc 12-6.hope this helps.

Marco:

If you want the scale look, try the Master Airscrew 3 blade
11 x 7. I wouldn't have any of their 2 blades, but I've got the 3
blades on four of my planes.

Randy

drywaller
by top end do you mean air speed or engine rpm? these type planes like air speed thus more pitch is good. it doesnt hurt to load the motor some. I mistakenly put a 10 x 5 ( 5 looked like an 8) on a 40 sized chipmunk the motor sounded great but did not want to hold level flite well. also depends on how lite the plane but for a 60 size 11x 7.5 dont sound too bad a place to start

7-1/2 pitch is certainly not too much for trial starter, but it's worth experimenting with 11x7, 11x8, 12x6 after you have a feel for your 11x7-1/2.

that the 11x7.5 is a good starting point. When tuning the engine it seems to offer more than enough thrust to pull this thing around the sky.
I have a feeling that an 11x8 or even 9 would be better suited.
I will be flying this plane around the middle of next week. I will let you know how it works out for me.
Marco.

Props: Tuned Pipe: 12x9, 12x10, 12x11
Sport: 12x6, 12x7, 12x8, 13x6, 13x7
Break-In: 11x7

those are the recommended prop's and prop ranges

Drywaller,
I fly several OS .61's both FX and FSR's, and I get the best overall performance with an APC 13-6 !

Ugly Stik 60, Goldberg Tiger 60, Hobbico Xtra 300
My flying is mostly "boring holes in the sky" so top speed isn't my #1 consideration. Ground clearance becomes important with some models too....
Happy Flying !

Drywaller, the 11x7.5 is an excellent starting point. The engine I assume is new so that will let it turn extra RPM's but It will be loud. All the feilds I fly at have noise limits so I am forced to use larger props (I use 12x9's on all my .60, which yeilds a sound level of around 92db), an 11x7.5 will yeild a 99 to 100 db while new but as it breaks in that can climb as High as 104db. If you don't have that restriction great!
My bet is you will like the 11x7.5 just fine but if you want to change props. You need to get a rpm reading while out at the feild. Once you have that you can find your top horizontal speed with the formula:

(RPM X Pitch) / 1056 = MPH.

RPM = Rotations per minute
Pitch = Pitch of the prop. In inches
MPH = Miles Per Hour

If you want to change prop.s you need to be able to compair them without having to buy them. You can do this with the formula:

Dia x Dia x Dia x Dia x RPM x RPM x RPM x Pitch = Hp
140000000000000000

Dia = Prop. Diameter
Hp = Horse Power

Pluging in the RPM's you got for the 11x7.5 you will get a Hp. We can plug that Hp into the next equation:

Cubed root((Hp x 140000000000000000) / (Dia x Dia x Dia x Dia x Pitch)) = RPM

Then using (RPM x Pitch) / 1056 = MPH we can see what that prop will do to our top speed in relationship to the 11x7.5 we alread flew it with.
Good luck.