[LEE]

What is the best prop to use on a U can-do 40 size with a Saito .65 4s? Bet one of you brilliant people know the answer, cause I don't Happy new Year everyone

[wingnut]

try a 13x4W (w is for wide blade)
this will give you baggs of torque and lots of verticle

[LEE]

Thanks, but this size is hard to find in reg. hobby shops. Guess I'll try to order from Great hobbies. For now I'll use a 13-6 reg APC.
Thanks

[Gary Maker]

Hi Lee,

According to the prop chart that comes in the Saito engine manual the recommendations for the .65 Satio are:

Prop 10 x 8 to 11 x 7.75 keeping the RPM within the range 2000 to 11,500 RPM.

The size your planning on using ( 13 x 6 ) is only recommended for Saito's .72 to .91 engines.

Check out the specs here: http://horizon.hobbyshopnow.com/products/saito.asp

Click on desired engine and then click on "Specs".

The way I see it, if an 11 x 7.75 gives you 11,500 RPM, you will have much less RPM with the 13 x 6 prop which is a whole 2.25 higher loading P-factor.

P-factor is: (D x 2) + Pitch = P-factor.
10 x 8 = P 28 ... 11 x 7.75 = P 29.75 This is your effective P factor range. A 13 x 8 would be P 32 or 2.25 over range!

Hope this helps!

[wingnut]

hey lee i just bought a 13x4 at my local hobby shop for 14$
it is Skycraft hobbies in Burlington ontario
but id also say that Great hobbies would have them tooo!

[cplant]

For 3D you want to keep the pitch quite low so I've found you can get away with a bit more diameter. At 4"pitch a 13 would be ok I think especially with a torquey four stroke. A 13x6 might be a bit much. A 12x4 would also probably work quite well. The best thing to do is experiment a bit.

A fellow at our field has a 46 UCD with a .46 Evolution in it and he insists on using a 10x7. The plane has no vertical at all (backs up in a hover at WOT). I use a similar sized and powered 2 stroke on a plane that is about the same weight with a 12x4 and the vertical is incredible (plane accelerates out of a hover and climbs at about 30mph out of sight) Another guy I know with the UCD 46 has an O.S. .70 Surpass in it with a 12x6 and it has no punch either. It has been recomended that he go as large as a 14x4 and I am inclined to agree. One thing you don't want to do with the UCD is overspeed it.

[tag]

I have to agree with these fellows. 13-4 wide blade is the prop to use. U-can-do is a 3d plane with 3d control surfaces. Why not use the 3d prop? What you want is lots of vertical torque but not much speed. If you want to fly fast then a 3d plane is probably not the right choice. Hope this helps.