Good Combo for E-Open B

Want to discuss OPEN electric combat items? Come on in! This is the place.

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Lee Liddle
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Post by Lee Liddle »

They work, I`ve run several of them, jsut keep an eye on the temps and make sure they get air.
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Air Scharnell
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Post by Air Scharnell »

Lee,
Thanks for the info on the motor/Lipo size
The E gremlin James was working hasnt gone any where yet.
So with 1 event left for us right now looking at some ideas for change, in our slow time for next year ...[;)]
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Air Scharnell
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Post by Air Scharnell »

Since Open B doesnt have a price penalty...
Have you tried a Medusa inrunner ?
Just wondering....
I have 3 mos too play before LSN
crash_out
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Post by crash_out »

There's always the Medusa's the flying wing guys like kilque uses...5 or 6 lithium cells can push the right one to well over 150mph...
Lee Liddle
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Post by Lee Liddle »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Since Open B doesn't have a price penalty...
Have you tried a Medusa inrunner ?
Just wondering....
I have 3 mos too play before LSN<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Hey Frank, nope no price limit/penalty, the biggie is the weight limit/penalty. You`ve got to be at less than 4 lbs RTF.

At this point in the technology curve, the only way to do it and stay competitive is speed, size (span) and duration, it to use a flying wing of some sort. I don`t think you`d be able to e-power an avenger and keep it under weight.

You could do it if you run smaller lipos and land and switch batteries mid heat. Nothing wrong with the Medusa motors except for the price, but the cheap Ammo motors have dried up so a good quality B motor will cost you about $75 minimum.

If you`d like some more info, shoot me an e-mail and i`ll try to help.
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Air Scharnell
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Post by Air Scharnell »

Lee,
Thanks for the info...
Yep looked at a Medusa and the price ouch...
Work has been a pain this past week and Im short on time at home.
Will try and do some more work with my Astro experiment this coming week-end....
3S 2000mah in parallel got me 14k on a 8x3 thats on my 8c Commonsense
crash_out
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Post by crash_out »

I've been eyeing the ARC motors that www.lightflightrc.com carries. I've spoken with the owner about them and he seems to think they can accomplish what I need...
sgilkey
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Post by sgilkey »

Brian's used several of the ARC motors and seems to like them, and the price is right. But he has broken a few shafts off at the front bearing. One was due to a broken blade/imbalance that happened so fast he couldn't throttle back and off came the shaft. The other happened yesterday, just a normal landing but in 20 degree weather and the shaft broke clean off. ARC will replace the motors for less than full price but still costs, I think, $35. These are 5mm shaft motors, I believe. Brian can comment more if he finds this thread....
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boiler
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Post by boiler »

Lee and others flying e open B. What are the weights of your motors? To keep e motors on a level field with ic a weight limit might be equivalent to the cid limit imposed on ic engines. Old topic here but we need to do some thinking so we can grow together instead of apart.
TheKid
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Post by TheKid »

The arc motors are 3.2mm shafts. And yes i have broken some. I think you'd have a hard time getting a 28mm (speed 400 or 480) motor to last 5 minutes at the neccesary ~watts. The problem is you need a low kv (a typical 28mm motor has a kv twice as high as you need), and with low kvs and high turn counts the internal resistance adds up and the motor starts running hotter.

The higher quality motor you get, the less waste heat is created. So if you use a really good motor (like neu, hacker, lehner etc.) you might be able to get away with a 5-6 oz motor. But if you run a stinky motor, you would have to add weight so it can cope with the heat.

I think the 36mm motors from lightflightrc.com (namely the 36-55-2T which has a 1450 kv) would be a good combat motor. They are 70 bucks new, and can be replaced for half price if something happens. And they have 5mm shafts. These motors might be a little bit over kill. BUt one thing to think about is

1) it'll cost more upfront. But instead of having to buy a new junky motor (40 bucks maybe?) you can just get it replaced for the same cost. So its about the same cost
2) Just by switching from a junk (inefficient) motor to a quality one you can gain 10% in rpm, just from the increased efficiency.

Like they say, buy quality buy once. Or something like that...

Lee have you tried any of your 36-55-2T in a combat plane? Or do you save those for the ducteed fans?
crash_out
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Post by crash_out »

I was thinking of the 36mm ARC motors. Yes, the 28mm with 3.2mm shafts wouldn't be large enough for combat, at least not SSC/Open/2548.

Yeah, Hackers are great, I like them...but 190-250 bucks for a B40 or B50 for use in combat is out of the question. $115 for a Neu is pushing it. Add to it Neu motors take 4-8 weeks for delivery(imagine what repair time would be...) and I'd rather buy a stock of cheaper $50 motors that I know I can get replaced in a few days.

Most of the viable motors I've seen range from 6-9 ounces. Like Brian said, the higher quality motors are going to weigh a lot less, leaving plane and armor options more open. For those of us using cheaper motors, we lose that much in airframe weight.

Overall, I don't think limiting weight is going to limit power output. A lighter weight Hacker would surely be able to out gun a heavier Turnigy....the only way I see to limit power otuput is to simply do that...Lee has established that SSC takes 300-350 watts to compete. B and scale require 600-650 watts. Either amp draw or voltage alone wouldn't be viable limitation, as one could simply add more of whichever isn't limited and acheive more power.
Lee Liddle
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Post by Lee Liddle »

It takes more than 650w to compete in open B.


Limit the horsepower of IC engines, then talk to me about limiting electric motors.

Sorry, but I`m done beating that dead horse.

If some off the wall proposal gets passed limiting electrics in Open B (like Kirk tried to do last cycle), then I`ll just fly IC.
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Post by crash_out »

Sorry, I was thinking in terms of Limited B....

Just for reference, what is the benchmark in Open B...ie, what props at what RPM...what does the typical .25FX with pipe turn with what prop to be competitive?
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o1moregil
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Post by o1moregil »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by crash_out</i>
<br />Sorry, I was thinking in terms of Limited B....

Just for reference, what is the benchmark in Open B...ie, what props at what RPM...what does the typical .25FX with pipe turn with what prop to be competitive?
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
my 25 fx are turning 21,000rpm (give or take a little) on a 8x5 apc (I'm @ 3000 above see level)
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Post by TheKid »

a .25 will turn a 9x4 at about 18k usually, and a 8x4 (for the wing guys) at 20-21k i think. I never wanted to get close enough to tach one of the 8x4.

Lee, weren't you running 1000 watts (input that is) on your open planes at some point?

One thing with the cheap motors though is that you are putting 1000 watts in to get say 700 out. But with one of the nicer brands you might only have to put 800 in to get 700 out. Thats a whole lot less battery and speed control you have to carry. I would love to see what someone could do with some good quality stuff...

I just got my first neu motor for my speed planes. 143 dollars after shipping, and i waited 10 weeks to get it (blah). Hope its worth it...

I think a Neu 1506 would be an ideal motor for combat...
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