opjose

Which is a good answer to the original question.

Effectively, when in doubt, test. That will give you more accuracy than anything else.

MikeL

My Feedback: (3)

Oh, you can do that, but it would be a foolish thing to do. It's great for knowing how long you can sit there in the backyard with four or five servos moving. Your idea of "average draw" is great, too, if a person actually knows what that is.

The point that you simply don't seem to be understanding is that you are recommending that people measure their system's capacity with an artificially low current draw, and use the time measured in order to determine the amount of time that is safe. I think it's great that you've now couched that highly specific method with "back[ing] off from what is measured for safety's sake" which surely wasn't in your initial bit of advice to Delbert. You want to use a fuel tank analogy? Use the right one--what you've suggested is the equivalent of seeing how long the engine will idle on the ground until out of fuel, and believing that to be an accurate representation of how long an actual flight could last.

Yes, I'm judging your advice. If you don't like people doing that, I'd suggest that you refrain from offering advice. We all form opinions about what we read. When we answer a question, we've got a responsibility to answer it based on either first hand experience or real knowledge. You've suggested methods that will lead people down the wrong path. You're unwilling to retract that advice, for whatever reason.

Does increasing the amount of airflow over a deflected control surface exert more pressure on that control surface?
Does more pressure on a control surface mean that a servo has to exert more physical force to attain or maintain a given position?
Do servos "fight" engine vibration, exerting more force to maintain a neutral control surface position than when an engine is not running?
Do servos draw more current when they have to exert more physical force to attain or maintain a given position?

Most of us can figure out that the answer to each of those questions is yes. Do you disagree? That article from Central Hobbies that I mentioned gives a measured current draw of 95mA on their test model (which is likely to be a YS four-stroke pattern ship, given what they sell) without the engine running. With the engine running at full throttle on the ground, the current draw went to 375mA. That's a huge difference, and the model isn't even flying. Is that a model that's likely to be representative of what is usually discussed here in the Beginner's forum? No, but the basic concept is still valid. It's very unlikely that a .40-size trainer will see a current draw that high from just running up the engine, but it surely will see a markedly increased current draw.

You gave this neat, simple little collection of methods, at least three of which bear little relation to what actually goes on when a model is flying. You can keep trying to put lipstick on that particular pig if you like, but it's a very bad idea to suggest that other people use those methods. If you want to do that yourself and try it with your models, that's your choice. I rather doubt that you have.

-pkh-

My Feedback: (2)

This is all dependent on the plane, the battery pack you installed, the servos you installed, how you fly, and how long a "flight" is.

Most people building a plane will put a battery pack in that they figure will last at least 3-5 flights. If you actually did this with your plane, then your instructor's advice holds. For example, a 600mAh receiver pack might get you 3-5 flights in a trainer with standard servos and 8 minute flight times. Put this same pack in a Twist 3D with high torque servos, 12 minute flight times, and really rip on it with some aerobatics, you'd probably be lucky to get one flight out of it!

I can get 3-5 flights out of most of my planes with some margin, but I use 1000mAh to 1200mAh AA-cell packs in my planes with standard servos, and 2300mAh A-cell packs in my aerobatic planes with high torque servos. If you start getting into giant scale planes, you're probably going to go with sub-C cell packs or LiPos.

kc31406

What in the world have I started here in this thread?

I'm learning more and more from this debate.

By the way, I get my [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXNK81&P=0]volt meter [/link] in the mail today. Hope I don't blow something up when I try it out!

jmurphy18

Dumb question time.... ESV????? Charger??
Thanks

bruce88123

ESV= Expanded Scale Voltmeter = a meter that allows you to check your batteries under a loaded condition. Better/truer indication than a normal/standard meter that doesn't apply a load.

Charger = the thing that puts the go juice back in your batteries. Use the proper type for the batteries you are using.

jmurphy18

Thanks Bruce! I had the impression you all were talking about a charger, but it did not make sense. I now know what ESV means. I did know charger as I have one

bruce88123

Ask any time you are unsure of what anyone is speaking about. We veterans sometimes forget not everyone instantly knows the lingo. I often learn new terms here too. If we talk over your head, it doesn't help.

kc31406

I agree!

I once thought AOL meant American Organization of Liars!

Sometimes I still do!

bruce88123

No that's Democ........... oops, not allowed to go there.

jmurphy18

ROTFLMAO!! to both
I always called them Loses on line Hated those acconts when I ran the track web site. [:'(]

kc31406

If I would charge my 600 mah receiver batteries on the quick charger at .60 until it beeps what reading would I be looking for on my volt meter? 4.9 - 5.1 - 5.8 - 6.2 ????

I'd like to know.

P-40 DRIVER

I would not make practice of quick charging your batteries but your volt meter should read in the green fully charged if you using that Tower meter.

stockdaddy

I like using this voltmeter:
http://www2.towerhobbies.com/cgi-bin...&I=LXWW16&P=ML

I fly till its down 4.6volts on 4cell NICD pack. I guessing that if when i land if for some reason my voltmeter reads below 4.25 volts, then i was flying unsafe and should up my starting limit.

The downside is now i have to take of my wings to read the volts each time. I'm thinking of getting something like this:
http://www2.towerhobbies.com/cgi-bin...&I=LXPNU3&P=ML

Not sure if there are cheaper/better options out there.

Being an electric flyer, i know all too well how they packs can be unpreditable and go bad without warning. I would check every flight and don't assume you are fully charged at proper voltage coming off the charger.

piper_chuck

My Feedback: (12)

I use these http://www2.towerhobbies.com/cgi-bin...?&I=LXJ778&P=7 on nearly all of my planes. They work great.