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Old Dec 05, 2003, 02:04 PM
Registered User
Monroe, NC, USA
Joined Jul 2001
104 Posts
Q-500, going electric

Since the Q-500 airframe is available in many forms and price factors, I would like to explore powering one with electric.

I would like to use two 6-cell packs with a brushless motor.

Would it be possible to get a 12 cell setup that will turn an APC 8.5 x 7.5 at 19,000 rpm's, or is that too much for a 12 cell setup?

Any and all comments of advice are appreciated.

________________

Don Stegall

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Last edited by PylonWorld; Dec 05, 2003 at 04:40 PM.
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Old Dec 05, 2003, 05:04 PM
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SoarNeck's Avatar
Calgary, Alberta
Joined Nov 2001
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I doubt you'll get those revs on that prop, with 12 cells. I thought of doing this exact thing myself, using a Hacker B50-6L direct, and a 105 Opto controller. Never got past the planning stages, however.
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Old Dec 05, 2003, 05:26 PM
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United States, GA, Atlanta
Joined Apr 2002
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remember though that just because that the glow guys are trying to wring out the maximum RPM out of that engine, that does not mean that this is the most efficient setup. Spinning that smaller prop ultra fast gives you a lot of pitch speed of course, but it also wastes a lot of power. A slower bigger prop is more efficient.

Instead of worrying about that exact prop size, concentrate on thrust and pitch speed and find a more optimal setup for that motor and wattage.

for example, if you used a hacker b5016XL on 12 SCR cells, and a 10x10 prop direct drive that would give you a thrust to weight just over 1 and still give a 100mph pitch speed. I assume that is enough? I am not sure how fast the q500 racres actually go...

remember, a well planned electrical setup is going to be much more efficient than the same glow setup. You can match the motor and gearbox to the prop and find the sweet spot.... The glow guys can only add more displacement....
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Old Dec 05, 2003, 05:45 PM
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Monroe, NC, USA
Joined Jul 2001
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SoarNeck,

Thanks for the reply.

How many cells would it take? I would like to stay with two 6 cell or 7 cell packs, although three 6 cell packs is not out of the question.

I've used the calc programs before, but I'm hoping someone who uses them on a regular basis can help me out.

If I could get 16,500 to 17,000 with an APC 9x6, that would be a start.

I plan to put a hatch on the side of the fuselage to access the batteries without having to take the wing off.


downeym,

A 424 (Q-500 Sport) plane goes about 110-120 mph. A 428 (Q-500) goes 160-170 mph.

The planes have 500 sq inch wings and the minimum weight is 3.5 pounds. The engines with the muffler weigh about 16 ounces.

I know that going to electric is going to increase the weight, but they have a very light wing loading, especially compared to Q-40's that have a minimum weight of 4 pounds and 400 sq inch wings.

What would a Hacker B5016XL on 14 SCR cells do with an APC 9x10 prop?

The problem is that most Quickie landing gears are just tall enough for 9" props, although that is not an insurmountable problem.

I would love for some of you electric guys to join RCPRO and serve on the Electric Racing Committee. I have molds for an all molded composite Q-500 and a Q-40 and would be glad to provide airframes (for free or nominal cost) to work on electrifying versions of those classes.
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Old Dec 05, 2003, 06:17 PM
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United States, CA, San Diego
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Quote:
Originally posted by PylonWorld
SoarNeck,

Thanks for the reply.

How many cells would it take? I would like to stay with two 6 cell or 7 cell packs, although three 6 cell packs is not out of the question.

I've used the calc programs before, but I'm hoping someone who uses them on a regular basis can help me out.

If I could get 16,500 to 17,000 with an APC 9x6, that would be a start.

Not even close--try 20 cells and 100 amps to get the RPMs you are looking for. FYI try the Aveox online motor test stand for some help. "http://aveox.com/hobby.htm"

Steve
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Old Dec 05, 2003, 09:16 PM
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San Diego, CA, USA
Joined Nov 2001
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Don,

This setup will get you your 19,000 rpm with the 8.5 x 7.5 APC prop with 20 cells. A lower number of cells would put the current so high that you would never get a speed controller to last.

Chuck

From Aveox's virtual test site
Virtual Test Stand Inputs

20 cells, Motor Type Aveox 36/38/1.5 (direct drive), APC Prop 8.5 X 7.5

Outputs
Prop RPM: 19741 RPM
Current: 99.1 Amps
Voltage into Motor: 15.1 Volts
Power Input: 1495 Watts
Power Output: 1344 Watts
Efficiency of Motor Only: 89.9%
Pitch Speed: 140 mph
Thrust at Pitch Speed: 77 oz
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Old Dec 05, 2003, 09:21 PM
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United States, GA, Atlanta
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the other part of the equation is how long is the race? at 100amps, a NiCd or NiNh cell would have to be pretty big to last long enough...
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Old Dec 05, 2003, 09:34 PM
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Monroe, NC, USA
Joined Jul 2001
104 Posts
A traditional AMA pylon race is 10 laps. Q-500 Sport on a 475' x 100' x 475' course usually is in the 1:20 to 1:40 time. We have raced 0.25 powered Q-500's on the 1/2A course (300'x60'300'). Around the same heat times.

100 amps requires a really expensive ESC doesn't it?

At one time I had looked at the Jeti Phasor 45/3 motor with a 70 amp controller. I know it won't be anywhere near the spec at the top of the page, but it may be an easy place to start. Or would it be a waste of time and money?
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Old Dec 05, 2003, 09:45 PM
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Calgary, Alberta
Joined Nov 2001
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Speed is expensive for sure, but there are deals to be had. I bought a geared B50 (carbon case) and a HM105 Opto controller for about $500 cdn a few months ago.

I wouldn't bother with a Phasor now, BTW. They're great sport motors (I have a 30-3), but popularity has driven the price above what I would consider their value to be. They also spin apart at high revs, lacking kevlar bindings around the magnets. Maybe used...
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Old Dec 05, 2003, 10:18 PM
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San Diego, CA, USA
Joined Nov 2001
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Quote:
Originally posted by PylonWorld 100 amps requires a really expensive ESC doesn't it?[/B]
The aveox SH-96 controller, rated for 100 amps costs $329.99. The Aveox 36/38/1.5 motor costs $149.95. (note these are list prices)

Also, at 100 amps twenty gold peak GP 3300 cells would last just under 2 minutes.

You may want to start with something with less performance and cost. But I would not suggest a Phasor or other similar inexpensive sport motor if high performance is what you want.

It is hard to beat Aveox's prices for motors, if truly high performance is what you are after.

Aveox motors are on sale at:

http://www.flydma.com/

Chuck
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Old Dec 05, 2003, 10:20 PM
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the other option woudl be to use a high voltage low current approach with LiPos... get the current down to about 40-50A but keep the watts high bu using more series cells...
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Old Dec 05, 2003, 10:50 PM
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Quote:
Originally posted by downeym
the other option woudl be to use a high voltage low current approach with LiPos... get the current down to about 40-50A but keep the watts high bu using more series cells...
You could, but you have to be very carefull about increasing the voltage too much, as speed controllers are presently not made for very high voltage. Aveox rates their high voltage controllers to be used with a maximum of 30 cells (nicad or nimh). The use of much more voltage will let the smoke out of the FETs. This is not a pretty sight even if your plane survives, which it may not. The controllers from other manufacturers have very similar voltage capabilities.

Now if you want to design your own higher voltage controller, you get into an area where the hazards of lethal electric shock starts to become a problem to deal with.

Chuck
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Old Dec 05, 2003, 11:02 PM
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Monroe, NC, USA
Joined Jul 2001
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Quote:
Originally posted by rcelectfly
...

Now if you want to design your own higher voltage controller, you get into an area where the hazards of lethal electric shock starts to become a problem to deal with.

Chuck
I know the brushless motors are more efficient than the brushed motors, but it occurred to me that I don't need throttle control, just on/off. I realize that is not an option with the brushless motors, but could there be an alternative with Lipo's and high voltage brushed motors?
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Old Dec 05, 2003, 11:02 PM
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for example, motocalc says that a B50 25XL with the same 8.5x7.5 with a 9s4p TP2100 pack will give you 18k rpm at only 30A! plus, this big pack will give 16 minutes duration. This should also be basically equivelant to the 30 cell limit on the controller you mentioned above.

Of course, you are going to spend $500 on batteries... but no one mentioned if we had a budget!
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Old Dec 05, 2003, 11:04 PM
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United States, GA, Atlanta
Joined Apr 2002
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also, obviously make sure you run a seperate receiver pack...
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