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Jul 05, 2006, 08:07 PM
Happy bluesman
hrbeta's Avatar
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Question

Electric power for dummies


Hello all,
I'm new to electric flight and I have a lot of questions 'bout engine sizes, batteries, controllers, etc., etc. Is there a site or perhaps a book on the subject where I can gather usefull info?
Thanks in advance.

hrbeta
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Jul 06, 2006, 09:16 AM
Master of 1 point landing
Quote:
Originally Posted by hrbeta
Hello all,
I'm new to electric flight and I have a lot of questions 'bout engine sizes, batteries, controllers, etc., etc. Is there a site or perhaps a book on the subject where I can gather usefull info?
Thanks in advance.

hrbeta
Yeah, this one - ask away and read all you can in your spare time
Jul 06, 2006, 10:37 AM
Registered User
Best thing is maybe to tell us what model, or type of model, you're thinking of getting, or what kind of flying you like to do (you're new into electric flight, does that mean you've got glow experience?). Then you'll get plenty of suggestions about motors, ESCs, and batteries, and you'll begin to get a feel for it all.
Jul 06, 2006, 12:14 PM
Registered User
hi there hrbeta,

Are you new to RC or new to the electric way of thinking?

I'm about three months new to the hobby and have spent *hours* reading threads on this web site. I can't agree more with the thought that you've found the place to do some good reading and learning.

Save yourself some of the bucks and frustrations I've learned and just read for a few weeks. RESIST the urge to buy that pretty sailplane and dig a $200 hold in the ground.

If you're hands on and have some bucks to toss around, may I suggest s GWS slow stick (or similar). Make the stock system work. Learn how to upgrade the battery to a LiPo first. That is, learn how to change one *easy* variable.

then read up on brusheless motors and ESCs for your slow stick and make a not-so-slow stick. I've gotten mine to where I can fly it on one Thunder Power 2100 mAh battery for 25-30 minutes!

The options to consider after upgrading one system are mind boggling. You'll learn how to juggle the variable:

Lesson Zero, and of utmost importance is safety. Please never ever charge a LiPo battery unsafely. If you don't think you know what "safe" means, stop right there! (It's not a secret, but don't cut corners learning important lessons here, read up!). Never ever charge a lipo battery unattended - a seemingly "fine" battery can swell up in 5 minutes and produce a 2,000 degree Fahrenheit fire.
Never charge a LiPo at a milliamp rating that exceeds the "1c" rating of the battery (e.g. I charge my 1320 mAh Lipos at 1.3 amps or less). Never, EVER re-use a battery that's been bent, poked, prodded or mis-shaped. Fires from these batteries can burn down your car/house/garage.
Never ever charge LiPo batteries using NiCad or NiMH charge modes. battery go boom.
(and more....)

Basics / Essentials that answer the "What electronics do I use..." question:
What's your Plane's weight?

What thrust vs. speed does the plane (and user) need to fly well? Often related issue: what size field you have to work with, and what is your experience with RC controls (do *you* need extra space, etc.)

Which prop sizes support the build, thrust required, amperage drawn and the limits that your ESC and battery have? Generally very related to prop/motor selection is to answer what gearbox is used if you are not in direct drive mode. (that is prop directly attached to the motor's spindle)

Learn how to estimate what power draw, thrust and speed differences occur when you change a prop on your existing setup? You *can* guess, and guessing *can* ruin equipment.

Learn VERY soon what a "too large" (too long in many cases) prop is for your setup and you'll not burn up your electronics. That 12 inch prop might look cool, but what if an eight-inch prop keeps your motor cool?!

what size motor to use. Don't skip the lessons on what WINDINGS you'll need if you are purchasing brushless motors; fewer windings cause the motor to run hotter, spin the prop faster, and pull more amperage. Learn what KV means on the outside of a motor box before you buy one and you'll save the $60 I've put into a neat, but not so useful motor.

what size electronic speed controller to use (20-25 amps is often sufficient for smaller/gentler setups, but some seemingly small planes can pull 30-40!)

Some More advanced things to learn:
When do you need to use a BEC? (what the heck is a BEC!)


One great way to learn if you can is tackle your local hobby shop guru, if you have one, you're lucky, and use them to help understand your questions and good answers. Try showing up off hours, not during the mad Saturday afternoon rush, and a good shop owner will spend time with you teaching you how this stuff works. My LHS has a few pros that have been gracious with their time, and in the end have also earned a dedicated customer.

One of the best ways I've learned (and am still learning) about power systems is to go find a thread on this web site that discussed a plane I am interested in (e.g. the humongous Slow Stick thread is in one the beginner's area), or the foamy do-it-yourself jets look like a lot of fun.

You almost need to know the kinds of questions to ask to get a lot from the power systems discussion. Start with a plane discussion on something you like and you'll see the types of questions more experienced folks have.

Enjoy the learning process, I have!
Doug
Last edited by dougaustin; Jul 06, 2006 at 12:29 PM.
Jul 06, 2006, 05:58 PM
Callsign: Jolly Roger
MyDigitalParadis's Avatar
Doug, very nice synopsys.

I've been flying electric for almost two years but till recently I simply bought preexisting combinations (ie Plane, Motor, Prop). Now I'm building my own and having to learn quickly about motors. I've two nice "little" motors where by the problem is just that, they are little. they resemble the E-flight 370's but do not have nearly the thrust.

Read through topics that look like they may relate. If you have a specific question use the search features. I'd have 10 times the posts I do now except that I can often find what I need to know that way. When that fails post your question. After you post it though don't quit "google" it. you would be surprised the resources available.

Have you flown before? If not a plane like the slow stick is a great place to start. It is easy to fly, has a fair number of options for upgrades, and if you buy smart almost all the electronics can be transferred to another, more advanced plane when the time comes. I only just recently retired my slow stick after 1.5 years of faithfull service. A mid air collision with a P-51 model brought her down. I didn't need to retire it though. The complete kit is only 35$ and in this case I only ruined the Prop, Center shaft and a couple of plastic pieces, about 12$ but I've too many other projects and decided to build them first.

Radio, There are many inexpensive radios but if you can buy a JR, FUtaba, or Hitech type. They have the most compatable hardware available including USB adaptors that allow you to connect your radio to your PC and using a flight sim like FMS (Flight Model Simulator) you can learn the basics before you leave the ground. I spent 250$ on my JR and it's 10 models and 6 channels makes it the only radio I've needed in two years.

First and formost though buy good quality equipment. If this is to be more than an experiment it will be money well spent.

Paul
Jul 06, 2006, 08:51 PM
Happy bluesman
hrbeta's Avatar
Thread OP

Thanks


Thanks guys for your comments. I was a dedicated slope sailplane builder/flyer some 30 years ago. I also logged a few hours on glow trainers. I'm very happy now to have found the newer generation of electric parkflyiers. They seem a lot of fun to me. I am setting myself up to start building and flying again. Lots of things have changed in 30 years (God, I sound old). I like the new materials like Depron and the sub-micro electronics, I can "digest" them with ease, but the electric motor world and its accessories I find baffling. I know this is a fine Forum and there is a lot of combined knowledge and experience here and I intend to learn from, and make the best use of, it. I'd just like to also have a direct reference source that I can consult. An "electric flight compendium" of sorts if such a thing exists.
Thanks again for your welcoming words. I hope we'll be in touch.
Hector
Jul 06, 2006, 08:58 PM
characters welcome!
Mark Wood's Avatar
Quote:
Originally Posted by hrbeta
I'd just like to also have a direct reference source that I can consult. An "electric flight compendium" of sorts if such a thing exists.
Almost everyone that has been in the hobby even a few months would agree that the problem with any non-dynamic attempt to capture such a thing would be obsolete even as it was published as there so many new things coming out almost weekly. See the Search tab at the top right of the page? That is your true friend and primary resource for finding the latest answers to your questions. It's easy to use once to get the hang of it and you will find most any information with the drop of a keyword or two.

Welcome (back) to the hobby!

mw
Jul 07, 2006, 03:56 AM
Registered User
It wouldn't do any harm to have a read of the "Electric Flight FAQ". It's not been updated for quite a while so parts of it are horribly out-of-date e.g. the batteries section has almost nothing about li-pos just NiCd and NiMH. But there's still SOME useful general information in there.

http://www.ezonemag.com/pages/faq/index.shtml

Steve


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