Smaller Propellers more Speed???? - RC Groups
Thread Tools
Oct 27, 2009, 10:48 AM
the answer 42 is

Smaller Propellers more Speed????


Im just a newby on this electric world , Im wondering why F5D planes use such small propellers (4x4.5)??

Besides I have a kind of F5D entry plane, now I have a 8x4.5 propeller it flys nicely and has some speed. I was wondering what would be the effect of just changing the propeller for something smaller, lets say a 6x4?? will this be enough to propell the plane?? will it go any faster than now?? or what will happend then ???

thanks a lo for your imput

Sign up now
to remove ads between posts
Oct 27, 2009, 10:52 AM
Registered User
rdbell's Avatar
Well I'm not an expert but the motor probably wouldn't be able to spin it fast enough because of its kV rating. Lower kV ratings are meant to turn bigger props at a slower speed and higher Kv ratings are meant to turn a smaller prop at a faster rpm. Something like a 2200 rating would be just about perfect for a 6x4.
Oct 27, 2009, 11:46 AM
Needs to do 52 legs !!
jjmouris's Avatar
Add a cell.
Oct 27, 2009, 12:22 PM
The Kid
Thekid3418's Avatar
For a given motor and cell count, a bigger prop will basically always be faster. If you went with a 6x4 your power would go way down, and you wouldnt have the available thrust if the 8" prop.

I would suggest if you want more speed
1) go with an 8x8 or similar
2) add a cell and prop down (6x6 or similar)
3) get a higher kv motor with a smaller prop (something around 3000-3200kv with a 5" prop)
Oct 27, 2009, 01:56 PM
Team Extreme! Team Twisted!
hercdriver7777's Avatar
It's all about pitch and RPM. Right now you have a 4.5 pitch prop. To go faster you either need to turn faster or increase the pitch and keep the RPM the same. If you were to go with a shorter prop, like a 6x4.5, it is possible that the motor might be able to turn it faster and your top end speed could be higher. That depends on whether the motor is capable of turning faster with less of a load on it. However, by going to a shorter prop you are giving up thrust to increase velocity so the plane will not accelerate from low speed as well as it did with a larger prop.

The next option is to add voltage to increase RPM of existing prop. Be careful because as you add voltage to the same prop/motor combo you will increase AMPs. You need to make sure your ESC can handle it.

Lastly you could just put a prop with more pitch on it. Diameter could stay the same or go smaller. The higher pitch will reduce the motor's RPM possibly so reducing the diameter and increasing the pitch may be optimal. It all depends on how the motor is handling the load of the current prop.

I'm sure you would get a much more precise answer if you gave us the make and model of the motor.
Oct 27, 2009, 02:11 PM
the answer 42 is
Hey woowo thanks a lot for all th information, the specs of the motor are:

Model : D2627-1200
KV (rpm/v) : 1200
Voltage (v) : 11.1
No Load Current (A): 0.7
No Load Speed (rpm) : 13550
Load Current (A) : 9.5
Load Speed (rpm) : 5800
Pull (g) : 550
G/A : 47.3
Weight : 40g (5g)

I used it before with a 9x6 propeller for a 1m glider I had and it can pull it very well.

so what would be your advise?? go back to a larger prop?? or a smaller one??



Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Zagi more speed? EJay Foamies (Kits) 2 Jul 19, 2002 12:07 AM
More speed from sp 400 DD than gear 370 ? RMason Power Systems 5 Jun 21, 2002 07:47 PM
More Speed 280 questions theKAT Parkflyers 0 Apr 24, 2002 08:36 PM
Smaller than a Speed 280? zbrubaker Parkflyers 10 Mar 18, 2002 12:51 PM
Anyone modified the TwinStar for more speed? Pierre Audette Foamies (Kits) 8 Jan 15, 2002 12:09 PM