Need advice on Batteries and ESC for my glider

[pierre sarault]

Hi - I need advice on batteries, ESC and running my e-flite inrunner to its full capacity.
I have a 68" electro-glider with a E-flite 28mm EFLM 2005 inrunner KV: 2700, 42 Amp max (12v max))(max 400W) and should drive a direct folding prop 6"X3" or 6"X6" at more than 18000 rpm (I'm hoping 2700X11v= around 20000 rpm?).

It is currently controlled by a Thunderbird 36 A ESC and some puny ThunderPower LiPo 1900 mah 2S (<4C) or 1380 mah 3S (<4C) with really small dia. wires and Futaba two-pin connectors (like on small park flyers...).

After Richard tried to launch this nice craft, it just didn't have the power to really take off; tests done @ home showed rpm to be a measly 9600...not much thrust and with a 8"X4" ...it just doesn't want to go higher than 5800!

Seems my batteries need to be around 2200mah with 50c rating and my ESC (because I'v limited the channel input on the 36A one to keep it from shutting down= too much current draw?) should be 50A with 2 to 3A ESC??

Comments, insights, suggestions are welcome!
Plus where do you suggest I purchase what's needed (so I don't have to wait weeks...)
P.s.: I'll have a 36A ESC, and a small inrunner and 2 small LiPo for sale!

Thanks a lot for the help, the advice...really appreciated!

Pierre Sarault
WIMAC member MAAC 60547
Tel.: 514-481-2617

[Burning Head]

Je pense que ton ESC 36amp est le minimum a y instaler, mais que les KV de ton moteur sont trop élevé et tes prop trop petite pour deplacer un oiseau de 68''WS. try a low KV motors around 900KV and biger then a 28 size canister,with a 11/8

[Burning Head]

regarde les specification de ce glider qui est plus petit http://www.greathobbies.com/productinfo/?prod_id=EFL2700 au lieu de 450 pour égaler le WS , le 480 BL 910 KV de E-flite http://www.greathobbies.com/productinfo/?prod_id=EFLM1500 ou meme pour regler le CG, un .10 , 1100kv http://www.greathobbies.com/productinfo/?prod_id=EFLM4010A. mais attend d'autre avis Pierre:cool:

[pierre sarault]

Merci Richard,
Ca semble etre une question de Brushless INRUNNER (le type que j'ai = direct drive = high rpm / low torque = plus petite helice tourne plus vite = poussee suffisante (?)) et les Brushless OUTRUNNER (ce que tu me suggeres = c'est le stator qui tourne = moins de rpm mais ++ de torque = plus grande helice = plus de poussee (thrust)) et peut-etre moins de courant?

Je ne cherche pas a faire de mon planeur un "Hotliner" parce que la structure de l'aile ne supporterait pas la grande vitesse et les "G" des "Hotliners"!

Evidemment j'aimerais ne pas avoir a changer le speed controller mais de toute facon il va falloir que je change de batterie et ca va me prendre un autre type de chargeur (J"ai vu les deux chez Great Hobbies ce matin). Autres idees?

Anyone have other ideas?
Merci / Thanks

[Burning Head]

Envoi un PM ou autre a Rich R:cool:dans la liste de la communotée, il est un genie de l'electro mathematique

[Kevin Rochon]

Rich is the King of Electric, oh yes also 3D.

And for motors etc.. another king is http://www.hobbyking.com/hobbyking/store/index.rc

[pierre sarault]

Thanks for the tips Richard and Kevin = much appreciated = the "Richard" you are referring-to, looking at the members' list = is it Richard Kearney?

[mdauth]

Thanks for the tips Richard and Kevin = much appreciated = the "Richard" you are referring-to, looking at the members' list = is it Richard Kearney?

RichR, est ce que tu as Le poids de ton avion.

[Burning Head]

Vas dans la section commuautée sur la bande noir de la home page, puis a membres, et tu devrais le trouver dans les R. Son nom est Richard Rambahal, il est le no 22 de haut en bas.

[pierre sarault]

Thanks Richard,
I just sent message to Richard (PM). I was looking at the WIMAC club members list...thanks for pointing me in the right direction!

Pierre

[RichR]

Hi Pierre,

I just read your PM, your glider's inability to launch correctly is due to the absence of thrust from your selected drivetrain. Attempting to spin a small diameter prop at high rpm works for pylon racer and F5D type aircraft where thrust isn't such an issue and top speed is vital, but will not work on a large and heavy airframe such as yours. There are many options to power your glider:

Option 1: Inrunner with gearbox (better for narrow fuse, higher efficiency)
Option 2: Outrunner with gearbox (less common, increasing in popularity)
Option 3: Direct Drive Inrunner (very uncommon)
Option 4: Direct Drive Outrunner (economical)

Your glider will fly from 10" to 14" props give or take an inch and prop selection will be dependant on potential motor weight and kV which affect total deliverable watts from motor.

For battery selection, a 3 cell lipo would best suit your glider, a capacity anywhere from 2000 mah to 2600 mah, with a discharge rate of 25C and above depending on the current you need.

As far as ESC, you could keep your Thunberbird 36 for the moment and verify current using a wattmeter or ammeter and if needed upgrade to a larger esc, such as a Thunderbird 54 if needed.

Please note that gearboxes are used to reduce the final drive ratio from higher Kv motors to allow the use of larger diameter props. Your current Eflite motor could work but you'd have to find a gearbox with an approximate 3:1 ratio which will allow you to use 12 inch props. Your motor Kv will effectively be 900 rpm /volt.

There are litteraly thousands of combinations that will fly your glider adequately, depending on the money you would like to spend and the quality of components you would like to use. On the lower end, you will find Hobbyking and on the higher end you can deal with Icare in Boucherville and purchase Mega, Plettenberg and moderately priced Axi motors.

In summary, swing a bigger prop on a suitable Kv(either by using gearbox or lower Kv motor) monitor your current draw and use appropriate ESC, and use a 3 cell setup!

[dmontesano]

and.......he's back. Richard, I miss your insightful analysis' on Aero Design

[Burning Head]

He is not only a EP magicien, but a hipnotizer too:).

[pierre sarault]

Ok, on reprend du debut - bonne question!

Le planeur pese 26 oz. avec un moteur brushless 6 pole inrunner 2700Kv, esc 36A, RX + 4 servos mais sans batterie - assumons 6 oz pour une LiPo 2100 mah/20C = total = 32 oz = 2 lb.. L'aile est de 68" et la surface est 3.72 pi.ca pour un wing loading de 8.6 oz./pi.ca.. L'aile est high lift - flat bottom.

Le manufacturier d'origine (Hacker-Modell) suggerait d'utiliser un brush-type Speed 480 (8.4vdc@20A max.) qui tournait une helice pliante 6"X3" (Graupner Cam) a environ 13,000rpm = vitesse d'ascension limitee mais suffisante.

Est-ce que mes options sont?:
1) D'utiliser le inrunner 6 pole 28mm de e-flite qui est fait pour remplacer le brush-type 480 mais qui pourrait tourner plus vite (11.1v X 2700Kv = 29,970 rpm (mais avec "load" ca pourrait baisser a 20,000 rpm?)) avec une 6"X3" ou une 7"X4" + de changer d'ESC (pour un 50A)(a acheter) + une 3S LiPo a 2200mah/20C ou 30C (a acheter)? {J'ai deja le inrunner 28mm/2700Kv et les helices 6"X3" et 7"X4"}.
2) L'autre option serait de prendre une helice 11"X8" (A acheter) avec un outrunner (quel modele?/ quel rating?)(a acheter), le meme ESC (36A) et une 3S LiPo 2200mah 20C (a acheter)?

La structure n'est pas concue pour en faire un "hotliner" (ou un planeur de haute performance et vitesse).

Your comments, advice, suggestions are welcome! Vos commentaires, conseils, suggestions sont bienvenues!

Pierre
MAAC 60547 / WIMAC
p.sarault@hotmail.com

[pierre sarault]

Hi Rich,

Thanks for your advice, as you probably saw, I sent another posting not having seen your msg. = oops.

So it looks like I'll have to go with option 2 = get an outrunner to swing and 11"X6" or larger with a 2200mah/25C LiPo.

Yes, Icare are a bit $$, so I'll do some shoppping...got to get a whole new setup including charger...

Thanks again!

p.s.: in my latest entry I provided the orig. specs of the glider (out of production, no one seems to dig V tails).

Pierre
MAAC 60547
p.sarault@hotmail.com

[pierre sarault]

Well, guess what - I tried option 1 = I replaced the 36A thunderbird ESC with a 54A and I tested it with the E-Flite Inrunner 6 pole series brusless with 2700Kv (40A max @ 11.2 V) and used a 12 v starter battery (test only guys...it would never fly!), just to be sure I had enough power available and guess what...there was plenty...got the Graupner 6X3 spinning almost at 20,000 r.p.m....the fuselage leapt out of the cradle despite the small bungie cords to hold it back and the prop crashed into the tach...and exploded (I had gloves and safety glasses). It tore the motor out of the mounting plywood disc and unglued that off the fiberglass fuselage...I was ...shocked!
After repairing and re-fastening the motor and mounting plate, I replaced the Graupner 6 X 3 blades and tried again this time with a few pounds of lead shot in the bottom of the stand and tighter bungie cords = spun it at 19900 r.p.m. and the thing just wanted to leap away. I then tried with an 8X4 with same blade design and could hold 17,600 r.p.m. ...we're talking 65% throttle (motor getting warm, not hot yet) and this thing was starting to pull the stand across the bench!. I also have a Robbe prop with 6.5 X 4 but I haven't tried it yet. This would suggest the I need a LiPo 3S 2000mah or 2200mah /20C to feed it doesn't it!?

[pierre sarault]

Thanks to all and especially RICH with your tips, definitions and advice for the powering of my Scorpion 68" W.S. electro-glider.

I didn't want to scrap my 6 pole 28mm 2470 Kv in-runner (3mm shaft) (which was a costly mistake)(Should have purchased an Outrunner) and I already had an 8X4 folding prop and I got a 56A Castle Creations Thunderbird ESC + BEC ...so what was I going to do?
I tried with a 12VDC starter battery to see what the result would be and the thing just pulled itself + the stand + 1lb of lead shot on my work bench and rammed my tach! It also tore the motor mounting plate right off the fuselage = Well that WAS ENOUGH THRUST!
So I purchased a 1800mah - 3S - 35C LiPo and charged it and tested it in the glider...after buillding and installing a laminated composite engine mount plate with cooling holes to match those of the motor.

I get 17800 r.p.m. at 70% throttle with an 8X4 and it really pulls. When maintained for a minute or so, motor, batt and esc. are just lukewarm...I just finished re-balancing the airframe and it looks promising!

Thanks to you all now lets see it in the air.:)