Jeddy

Hi,
Please can anyone point me to useful websites for an electric virgin? I have a load of gliders and would like to stick electric motors in a couple of them (they are designed with electric motors as an option), however I'm totally confused by all this electric stuff... All sorts of questions come to mind

How do I know how much power I need (how do I work out what power depending on whether I want to launch it vertially or just manage to limp back to the slope when all the lift goes).
How many cells should I use (one is going to be 8 for space reasons, the other could be loads) - what sort of cells AA, C's etc ???
What's all this AR stuff on batteries?
How do I know if I need a gearbox, and if so what sort?
How do I know what prop - pitch / diameter I need?
What are conventional and outrunner motors.
etc. etc..

all sorts of questions.

I won't trouble you for answers, but if someone could point me to a website that could answer these questions (as well as questions I don't even know to ask yet), that would be much appreciated!
Thanks.

Matt Kirsch

My Feedback: (21)

Many of your questions can be answered using the search feature on this and perhaps other forum sites. Other resources include Red's R/C Battery Clinic www.rcbatteryclinic.com. The E-Flight FAQ at www.ezonemag.com is an invaluable resource. We really need one here, but everyone's too busy flying

Say, I am going to start a thread requesting questions for an Electric FAQ in Electric General Discussion. I'd appreciate it if you listed the questions you posted in this thread there.

One of your questions in particular is not going to be found in a FAQ, though. There are many ways to determine how much power you need, and a few schools of thought. All of them, though, depend on the size of the plane and the desired performance. I often use the Watts-per-pound method that basically states for a given amount of performance, power the airplane with so many Watts per pound of all-up weight. You kinda need to know the weight of the power system for this to work, but you can go through several iterations to get an accurate weight, or overestimate.

Normal gliders start out at 50 Watts per pound, and full-blown F5B racers are running at least 150 Watts per pound, maybe even 200. From there, you'd translate it into Volts and Amps. If you plan on running the motor for long periods, a low Amp draw and more Volts will keep the motor cooler, and the batteries will last longer. For zoom launches and short motor runs, you can run high Amps to keep the battery weight down. Your run-of-the-mill Goldberg Electra with stock power system will run about 25 Amps on 6 cells, while a full-blown F5B will run 200 Amps on 20+, IIRC.

Cell size will depend on how many Amps you're going to draw. For anything over about 25 Amps, you'll want Sub C cells in most cases. It's less confusing if you don't try to decipher the letters on the batteries. There's no one system used by all manufacturers. Even one manufacturer uses several systems. Just treat them as simple model names. Sanyo HR4/5FAUP == Ford Focus.

Jeddy

Thanks, that Ezonemag one looks like what I was looking for!!

Matt Kirsch

My Feedback: (21)

You've got to promise that you won't go over to "The Dark Side" (join ezone and abandon us), though

Oh, and I posted that thread, but I don't see your quesitons!!! Get busy!

akahoverit

My Feedback: (2)

Who sells jeti esc's besides hobby lobby?

dbl8ts

Dear a.k.a. hoverit:

Why are you so anti-Hobby Lobby? What did they do when you tried to order the Jeti? What did you chew them out about regarding your order?

Dr Kiwi

I'm only half anti-HL and half anti the State of Tennessee - I live in TN and HL charges $7.99 for shipping (only 120 miles), which is iniquitous: (I can get stuff from Japan, ?6000miles, quicker, for $2.50): but, even worse, the state of Tennessee adds 9.25% State Tax to every order I put in.

I wonder why I order from "out-of-state" on the Internet?

Cheers, Phil

Peter Khor

My Feedback: (4)

Phil, HL has $2.50 shipping if items fit in 4" cube shipping box. Call 'em. Can't help with the tax though

Matt Kirsch

My Feedback: (21)

How did this turn into an anti-Hobby Lobby thread?

FWIW, I remember reading that akahoverit's problem with HL is that they rejected his credit card because the address on the card didn't match the shipping address he provided. He'd recently moved, and hadn't updated his credit card yet. Blame the scamming scumbags for that policy, not Hobby Lobby. Credit card companies charge a fee for every transaction. The less secure the transaction, the higher the fee. This is why you see companies requiring the CVV2 number, and why some require the shipping address to be the same as the billing address on the card. They get a break from the credit card company.

You want this stuff to be available, and you want it cheap, then you've got to be willing to jump through some hoops to get it.