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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 :shock: Happy new Year everyone :cheers:
01-03-2004, 10:23 AM
try a 13x4W (w is for wide blade)
this will give you baggs of torque and lots of verticle
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.
01-05-2004, 03:25 PM
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!
01-05-2004, 05:33 PM
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!
01-05-2004, 10:03 PM
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.
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.
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