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Dec 17, 2017, 11:33 AM
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Poll

hobbico nextstar conversion


Making it a taily..and electric power. What ya think?
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Dec 22, 2017, 05:32 PM
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Big tundra tires. 4270 mah 6s lipo. Swinging a 15 x 7 prop. Should be sweet.
Dec 23, 2017, 01:23 PM
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Which electric motor are you using?
Dec 23, 2017, 04:28 PM
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Scorpion 4025-12
Dec 23, 2017, 06:05 PM
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Not my best covering job..but hey..i hate monokote brand. Its all i had on hand..and its a bang around plane anyway. I prefer black baron film. No wrinkles..shrinks up nice.
Dec 23, 2017, 08:01 PM
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Quote:
Originally Posted by emoor1978
Making it a taily..and electric power. What ya think?
I think thats awesome, and much better than originally designed. I prefer taildraggers and I prefer e power. Thats great.
Dec 23, 2017, 08:36 PM
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I had one of these. Flew it a while then set it up for fpv and using a vector flight controller. Kind of a plane for trying out gear.

Picked it up dirt cheap on the web while surfing. Thought I would try something different. Converted to epower, had a g46 motor on 5s for power. Used it on some farm land in a tight field I fly from. Bigger tires, beefier landing gear etc. I beat it up pretty good. Pulled all the stuff out and what is left of it is in the attic now. Fun plane.
Dec 24, 2017, 01:46 PM
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Its all done. Weighs 8 ounces less than the stock glow version. And i overpowered it . Its a flat 6 lbs. Rtf. I fly from a private farm strip i made..its tight flying..so i made some mods to it. Larger wheels..heavier gear..and more control throws.
Dec 24, 2017, 11:58 PM
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vollrathd's Avatar
Quote:
Originally Posted by emoor1978
Its all done. Weighs 8 ounces less than the stock glow version. And i overpowered it . Its a flat 6 lbs. Rtf. I fly from a private farm strip i made..its tight flying..so i made some mods to it. Larger wheels..heavier gear..and more control throws.
Yeah
Now days it's easy to match or exceed the power of a glow engine with a quality electric power system.

I've posted this several times in RCGroups and elsewhere. Perhaps other readers will find these numbers useful.
Dec 25, 2017, 10:30 AM
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Quote:
Originally Posted by vollrathd
Yeah
Now days it's easy to match or exceed the power of a glow engine with a quality electric power system.

I've posted this several times in RCGroups and elsewhere. Perhaps other readers will find these numbers useful.
An E-Flite Power 46 electric motor only has 453 watts output? I read elsewhere 746 watts is needed for a typical 40-46 size glow trainer trainer.
Dec 25, 2017, 11:36 AM
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vollrathd's Avatar
Quote:
Originally Posted by ramboy
An E-Flite Power 46 electric motor only has 453 watts output? I read elsewhere 746 watts is needed for a typical 40-46 size glow trainer trainer.
I have a similar sized Hacker A40-10L motor that is turning a 13X10 APC-E prop at 7500 RPM, around 650 Watts. This motor is rated at 1100 Watts. Years ago, I ran that A40 motor in an 8 pound P-51 model, running at the 1100 Watt rating. It flew well.

Also gave a Rimfire 50 cc motor, running 4500 Watts in a 23 pound airplane. That power system hauls the model straight up out of sight.

And, also have a dozen other models, ranging from a few hundred Watts to 2800 Watts. None are underpowered!

Don't know how many 40 sized glow engines can put out 746 watts with a reasonable prop, IE not turning over at 15K RPM. That 750 Watts is in the area of a 70 sized four stroker glow engine.
Last edited by vollrathd; Dec 25, 2017 at 12:31 PM.
Dec 25, 2017, 01:03 PM
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Quote:
Originally Posted by vollrathd
I have a similar sized Hacker A40-10L motor that is turning a 13X10 APC-E prop at 7500 RPM, around 650 Watts. This motor is rated at 1100 Watts. Years ago, I ran that A40 motor in an 8 pound P-51 model, running at the 1100 Watt rating. It flew well.

Also gave a Rimfire 50 cc motor, running 4500 Watts in a 23 pound airplane. That power system hauls the model straight up out of sight.

And, also have a dozen other models, ranging from a few hundred Watts to 2800 Watts. None are underpowered!

Don't know how many 40 sized glow engines can put out 746 watts with a reasonable prop, IE not turning over at 15K RPM. That 750 Watts is in the area of a 70 sized four stroker glow engine.
746 watts = 1 horsepower. An OS 46 LA puts out about 1.2 horsepower.
Dec 25, 2017, 01:34 PM
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vollrathd's Avatar
Quote:
Originally Posted by ramboy
746 watts = 1 horsepower. An OS 46 LA puts out about 1.2 horsepower.
At what RPM and on what prop?

I'm well aware of conversions between HP and watts, and all sorts of other conversions. One very useful cellphone calculator is provided by realcalc. This calculator has built in conversions between a wide variety of items.
https://play.google.com/store/apps/d...RealCalc&hl=en

My Hacker A40-10L is rated at 1100 Watts, or around 1.47 HP. Don't know if an OS 46LA would be capable of flying an 8 pound P-51 model with a 62 inch wingspan.
Last edited by vollrathd; Dec 25, 2017 at 01:43 PM.
Dec 25, 2017, 02:45 PM
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Hubert1's Avatar
Thanks for those downloads, will have to read them through. I'm converting an avistar elite to electric, going to be using a 6s 5000 mah battery, but I'm having a hard time picking the right motor/esc combo.

Merry Christmas!

Hubert
Dec 25, 2017, 05:22 PM
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vollrathd's Avatar
Quote:
Originally Posted by Hubert1
Thanks for those downloads, will have to read them through. I'm converting an avistar elite to electric, going to be using a 6s 5000 mah battery, but I'm having a hard time picking the right motor/esc combo.

Merry Christmas!

Hubert
This model runs about 7 pounds or so. With 150 Watts per pound, you will have a model that won't be underpowered. So, you're looking at a 1000 Watt electric motor. Something to be aware of though. Those electric motors can turn a larger diameter propeller than a similar horsepower glow engine. You've got to watch for ground clearance on those larger diameter electric props.

There is a very wide variety of electric brushless motors that will fill the bill. One would be a Hacker A50-12S. Or the Hacker A40-10L. Nice thing about electric power. If the A50-12S motor has to much power for your needs, just hang a smaller prop on it.

Here is the motocalc evaluation on the A50 motor in the Avistar

MotOpinion - Elite
Sea Level, 29.92inHg, 59F

Motor: Hacker A50 12S; 500rpm/V; 2.5A no-load; 0.016 Ohms.
Battery: Thunder Power TP5000 (G4 ProLite 20C) (20C); 6 cells; 5000mAh @ 3.7V; 0.006 Ohms/cell.
Speed Control: Generic; 0.001 Ohms; High rate.
Drive System: 13x8 (Pconst=1.31; Tconst=0.95) direct drive.
Airframe: avistar elite; 670sq.in; 115.3oz RTF; 24.8oz/sq.ft; Cd=0.054; Cl=0.47; Clopt=0.71; Clmax=1.24.
Stats: 153 W/lb in; 138 W/lb out; 23mph stall; 30mph opt @ 50% (61:07, 93F); 37mph level @ 59% (47:30, 99F); 2452ft/min @ 66.7; -271ft/min @ -5.8.

Power System Notes:

The full-throttle motor current at the best lift-to-drag ratio airspeed (54A) falls approximately between the motor's maximum efficiency current (56.2A) and its current at theoretical maximum output (632.6A), thus making effective use of the motor.
The voltage (20.2V) exceeds 12V. Be sure the speed control is rated for at least the number of cells specified above.

Possible Aerodynamic Problems:

The static pitch speed (72mph) is greater than 3 times the stall speed (23mph), which might make take-off or hand launching difficult, and is inefficient in flight unless high speeds are intended.
Pitch speed can be decreased by using a lower pitched and/or larger diameter propeller, a higher gear ratio, a lower cell count, or some combination of these methods.

Aerodynamic Notes:

With a wing loading of 24.8oz/sq.ft, a model of this size will have flying characteristics suited to the intermediate pilot, for use in calm to moderate wind conditions.
The static thrust (141.4oz) to weight (115.3oz) ratio is 1.23:1, which will result in extremely short take-off runs, no difficulty taking off from grass surfaces (assuming sufficiently large wheels), and vertical climb-outs. This model will probably be able to perform a hover or torque roll.
At the best lift-to-drag ratio airspeed, the excess-thrust (100.2oz) to weight (115.3oz) ratio is 0.87:1, which will give very steep climbs and incredible acceleration. This model can easily do consecutive loops, and has sufficient in-flight thrust for any aerobatic maneuver.

General Notes:

This analysis is based on calculations that take motor heating effects into account.
These calculations are based on mathematical models that may not account for all limitations of the components used. Always consult the power system component manufacturers to ensure that no limits (current, rpm, etc.) are being exceeded.




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