STEVESRCWORLD

My Feedback: (23)

HELLO,
I need some help finding a prop for my 400 motor. it has the 4200kv and will be running a 3 cell lithium battery. it goes in a new glider which i have never had before and i don't know what size folding prop i need for it. glider is 63" wingspan and weighs a little over a pound. i would like to have a fast speed but also good pull for climbing. the spinner size is 1 1/4 inches to fit the glider. i measured the motor shaft and it is .078 or 5/64 or 1.8 mm and i don't know what to do. please help put me in the right direction. thanks all

Matt Kirsch

My Feedback: (21)

Direct drive, that motor won't turn more than maybe a 5x4 prop without drawing too many Amps. It's not going to perform well in the nose of a draggy sailplane. A gearbx will allow the motor to turn a much larger prop for much better efficiency.

Dr Kiwi

I'm not guaranteeing the Motocalc calculation, but this gives you an idea of the right way to go (the motor is rated (optimistically) at 18A continuous).

Motor: E-Flite Park 400; 4200rpm/V; 1.8A no-load; 0.24 Ohms.
Battery: Thunder Power TP2100 (ProLite) (15C); 3 cells; 2100mAh @ 3.7V; 0.018 Ohms/cell.
Speed Control: Castle Creations Phoenix 35; 0.0045 Ohms; High rate.
Drive System: 13x8 (Pconst=1.11; Tconst=1) geared 5.33:1 (Eff=80%).
Airframe: Anything you want.
Motor Amps = 15.5
Motor Volts = 10.2
Input (W) = 157.6
Motor RPM = 20064
Prop RPM = 3764
Thrust (oz) = 20.3
PSpd (mph) = 28.5

Maybe this might do it better:

Motor: E-Flite Park 400; 4200rpm/V; 1.8A no-load; 0.24 Ohms.
Battery: Thunder Power TP2100 (ProLite) (15C); 3 cells; 2100mAh @ 3.7V; 0.018 Ohms/cell.
Speed Control: Castle Creations Phoenix 35; 0.0045 Ohms; High rate.
Drive System: Direct Drive Propellers; 9x7 (Pconst=1.11; Tconst=1) geared 3:1 (Eff=80%).
Airframe: Anything you want.
Motor Amps = 15.8
Motor Volts = 10.2
Input (W) = 160.4
Motor RPM = 19108
Prop RPM = 6369
Thrust (oz) = 12.9
PSpd (mph) = 42.2

Phoenex

My Feedback: (1)

The shaft size is 2mm. The motor is not reccomended and was never designed to be used for direct drive with the shaft that small. You need to get together with someone with experience in electric planes to help you with motor/mount, gearbox-prop setup etc. as these issues are detailed and tailored to the plane. The local hobby shop may be able to help you. All parts of the power system battery, motor, gearbox, prop, speed controller must be matched to work together with the plane or you will have major problems.

Edit-This post was not in reply to Dr. Kiwi (I would be speaking to choir). I clicked on the wrong reply by mistake, the reply was meant for the thread starter.

VOLUNTEER

Here's the page for your motor. Look at the bottom for the prop/gearbox recommendations. I have the 400 outrunner on a 19 oz Stevens Aero Styk and it flies great.

[link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=EFLM1100]Horizon[/link]

STEVESRCWORLD

My Feedback: (23)

well i got on hobby lobby's website and they sell a graupner 4.7 x 2.4 folding prop to fit a 2mm shaft. i ordered it just to see what happens they say it works fine and they sell a lot of them that size for the 400 motor. the splane i'm building is the monton sold through giant scale planes. i must say that it looks very nice and it builds well and quick to. the wings are thin and so is the fuselage so it may not take much to fly it. can somebody run the motocalc's on the prop that i have ordered? i will be using a 1700 mah lipo at 20c discharge.

Dr Kiwi

Well - this is what Motocalc says you'll get - okay for an 8oz, 36" span plane - but nowhere near enough thrust for a 16oz, 63" monster. I reckon that tiny prop will just be whizzing around pulling nothing.

Motor: E-Flite Park 400; 4200rpm/V; 1.8A no-load; 0.24 Ohms.
Battery: Thunder Power TP2100 (ProLite) (15C); 3 cells; 2100mAh @ 3.7V; 0.018 Ohms/cell.
Speed Control: Castle Creations Phoenix 25; 0.0065 Ohms; High rate.
Drive System: Direct Drive Propellers; 4.7x4.2 (Pconst=1.11; Tconst=1) direct drive.
Airframe: Anything you want.
Motor Amps = 15.6
Motor Volts = 10.2
Input (W) = 158.7
Prop RPM = 19375
Thrust (oz) = 8.8
PSpd (mph) = 77.1