West Wings Fournier set up

[Levanter]

I am at the fitting out stage of a West Wings Fournier and I have virtually no electric experience.

1500 wingspan
Around 1000g

It has been such a long time since I bought all the bits on the recommendation of a model shop but I didn't label everything. This is what I hope to use:

Eflite Park 370 motor - 1360 kv
JP Energy Pro ESC Programmable 20A ESC
Graupner CAM folding prop 8 x 4.5
Overlander LiPo 1600 mAh 3s

Does this sound about right please to the many wise people out there.

[Fun Flyer]

I just ran your numbers through my home brew electric flight calculator and it suggests a 900 to 1200 kv motor, 9" to 11" prop and a 30A ESC.

[Geoff S]

All your electrical parts (motor, esc, prop and battery) match OK and should deliver about 150 watts at around 10 to 12 amps. The maximum continuous current for the motor is 12 amps according to the data I've seen and ideally should be checked when you first operate.

So what remains is if 150 watts is sufficient for the Fournier and that depends to some extent on its weight. It's a glider but the full size was aerobatic. It'll probably fly OK if it weighs under 1kg but the lighter the better.

So a definite may be

Geoff

[gangster]

Hi Levanter. I don't think you will be far off the Mark with the stuff you have got. Possibly might need a slightly bigger prop Mine is on Kms 31/12 and a 9x5 prop. About 120 watts. Only flown it once I need to look at the wings to make it , in the words of the song, straighten up and fly right.

[Shed dweller]

I have a West Wings Fournier that flies fine on a speed 400 with a 7x3 prop and a 2S 2000mah lipo. That is about 50W power. I can't recall the weight, but it was built as per the kit (but with ailerons). It started life with an 8.4v 500mah nicad and has always been a good flyer.

[PatMc]

Based on test results when I've ran other motors around the same Kv with the same prop & 3s battery, I think your motor, prop & battery combo will draw around 20A - 24A. Your motor is only rated at 12A continuous so IMO you really need to think about either a smaller prop, dropping to 2s or changing to a lower Kv motor.
It would be best to do a test run with a wattmeter connected but open the throttle slowly & close it if the current rises above 10 - 12A unless the throttle is near fully open.

Personaly I'd be loathe to use a 2s battery instead of 3s but it should still give enough power.
IMO a smaller prop would be better but I'm not sure what's available in folders around 7 x4.
A different motor could be worth considering.
Have you checked the model's cg with the hardware listed in place ? I suspect that you may need to add some nose weight, if this is the case a heavier lower Kv motor (900 -1000Kv) could be the best option. You should be able to get a suitable 28mm motor for around £10 - £15.

[Levanter]

Thanks indeed everyone. I have tried to keep the tail and the all up weigh as light as possible. Given the balance of opinion being quite positive I am doing a dry run on the equipment to get a rough idea of the cg. Covering, it seems, puts a surprising amount of weight at the back end. One of the problems of a larger motor is restricted space and some surgery would be needed. Will let you know how I get on.

[gangster]

Do you own a watt meter? It is an essential tool for this type of experiment and fairly inexpensive . From the figures quoted you could cook that little motor with the wrong prop. I reckon keeping to the 12 amps will give plenty of power for the Fournier and hopefully no cooling issues in that tiny restricted nose and a reasonable flight time with the little battery. I have a 1300 3s which is a close fit through the hatch

[Levanter]

Thanks Gangster. I did buy a wattmeter and this can be its first outing. I think the motor will take 150 watts but is that continuously or peak? I am hoping that the motor will be able to be cut or reduced to do some gliding or soaring.

[Geoff S]

This will give you the motor spec. So you know its limits

Geoff