What prop and Li-Po should I use?

[arko66]

Hi. Yet another q from an electric flyer.

Who could recommend a good prpop and Li-Po for the following Kit and power-combo?

 

Seagull Edge 540 EP:

 

Wingspan - 42.7ins. (108.5cm)

Wing area - 376.7sq.ins (24.3sq.dm)

Length - 38.8ins (98.6cm)

Approx flying weight - 2.4-2.9lbs (1100-1300g)

I have the HiModel HiModel BL2820-07 (500W) 919Kv Brushless Motor & 60A 'Professional' ESC:

 

SPECS:
* Voltage: 3-4S Li-Poly
* RPM/V: 919kv
* Cont Current: 35A
* Max Current: 45A
* Dimensions: D38 x L46.9mm
* Shaft diameter: 5mm
* Weight: 145g
* Motor Mount: Included
* connectors: 3.5mm Gold 'Bullet' Included
* Recommended model weight: 800-2400g/5.1 lb

Hi-Model 60-80A Professional ESC SPECS:
* Output: 60A,
* Max Output: 80A (10 Secs)
* Input Voltage: 5.6v - 23v
* Lithium Cells: 2 - 6S **See note at bottom
* NiMH/NiCad 5 - 18 Cells
* Super BEC: YES
* Super BEC Output: 3A
* Size: W,29mm x L,57mm x H,19mm
* Weight: 45g

 

I cant get my head around the "Prop Info" that is supplied with the motor. (Thats due to me being a complete NOOB!)

 

Just want to go ballistic (in-flight and extreme!)

 

My motto should be... "Dont rush me ....I CAN go slower!

 

Thankx in advance

Ian.

[Former Member]

[This posting has been removed]

[Garry Pollard]

Try e-mailing BRC Hobbies, the have a e-mail enquiry form on their site. It says a reply will be with you in 3-5 days, never had to wait more than 5 mins

Garry

[Tim Mackey]

Well Ian its really quite simple TBH - the bigger the prop ( in diameter or pitch or both ) the more power you will have.

Of course, prop selection will also determine flight style as well - - -

big diameter = high acceleration or torque  but not top speed ( like a car in low gear ).

small diameter and big pitch = high top speed less acceleration or torque ( high gear ) 

You say you want ballistic and extreme - but please remember that any airframe has limitations and aiming for the full 500 Watt capability of the motor may exceed that limit - I have seen this happen with exactly this model.

Personally I would not aim for more than around 150 Watts per pound unless you are sure of the integrity of the airframe. On your maximum likely AUW of 3lbs that means 3 x 150 = 450 Watts. For this amount of power you maybe need to use 4S lipo to keep the current reasonable, and the revs quite high and you MUST stay within the motor max of 500Watts and 35 - 40A.

450 watts divided by 4s lipo voltage ( 14v) = 32A so you are well within limits, and decent quality 4s LiPo of around say 3000maHr capacity will see good flight times too.

Now as for the prop - well thats where a whattmeter comes in - if you dont have one then buy one if you are at all serious about getting leccy flight right.

The guidelines for props on this motor suggest that on 4s Lipo a 12 x 6 prop should pull around 40A and that means approx 560 Watts so seems a tad high to me. If using 4s then I would go down a bit and try say an 11 x 7 and see what meter reading you get. Then fly it, and if you want more,,, gradually go up in prop size and use the meter each time to check the figures are within maximum allowed.