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Old Jun 25, 2009, 11:15 PM
Vintage Flyer
Indiana
Joined Jan 2005
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Discussion
Playboy Senior 80 inch wingspan gas to electric conversion

Hi guys!
I am attempting to convert a Playboy Senior ( 80 inch span) from a .35 Fox gas engine to electric power.
The guiy at the LHS sold me an E-Flite Power 10 brushless Outrunner rated at 375 watts with a 3S1P lipo at 20C with a Castle Creations 36 amp ESC.
My AUW without motor and battery and ESC is fast approaching 3 lbs.
I want this thing to perform and climb like a good running Fox .35 was on it.
Is this electric setup good enough or will it be doggy?
IEverything from the LHS is still nIB and I have my receipt if I need something different.
Asking for some advice here. Prop is a 10/7

Thanks!
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Last edited by Ercoupe Ed; Jun 25, 2009 at 11:25 PM.
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Old Jun 26, 2009, 03:41 AM
Light and floaty does it
Work in Progress's Avatar
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Joined Sep 2004
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You might be near the limits of the ESC on a 10x7 prop, so check the peak current carefully.
Modelling it with MotoCalc using a GWS 10x6 HD prop and assuming a 3300 mA/h battery, it seems to go pretty well. 1000 feet per minute climb at better than 35 degrees climb angle. What does it do on a Fox 35?

***

Motor: E-Flite Power 10 Outrunner 1100KV
Battery: Polyquest PQ-3300XP (20C); 3 cells;
Speed Control: Castle Creations Phoenix 45; 0.0026 Ohms; High rate.
Drive System: GWS 10x6 HD; 10x6 (Pconst=1.23; Tconst=1) direct drive.
Airframe: Playboy Senior; 800sq.in; 61.7oz RTF; 11.1oz/sq.ft; Cd=0.045; Cl=0.5; Clopt=0.69; Clmax=1.12.
Stats: 88 W/lb in; 67 W/lb out; 16mph stall; 20mph opt @ 45% (61:34, 47F); 23mph level @ 50% (53:32, 50F); 1029ft/min @ 36.1; -141ft/min @ -4.6.
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Old Jun 26, 2009, 10:10 AM
Vintage Flyer
Indiana
Joined Jan 2005
1,674 Posts
Quote:
Originally Posted by Work in Progress
You might be near the limits of the ESC on a 10x7 prop, so check the peak current carefully.
Modelling it with MotoCalc using a GWS 10x6 HD prop and assuming a 3300 mA/h battery, it seems to go pretty well. 1000 feet per minute climb at better than 35 degrees climb angle. What does it do on a Fox 35?

***

Motor: E-Flite Power 10 Outrunner 1100KV
Battery: Polyquest PQ-3300XP (20C); 3 cells;
Speed Control: Castle Creations Phoenix 45; 0.0026 Ohms; High rate.
Drive System: GWS 10x6 HD; 10x6 (Pconst=1.23; Tconst=1) direct drive.
Airframe: Playboy Senior; 800sq.in; 61.7oz RTF; 11.1oz/sq.ft; Cd=0.045; Cl=0.5; Clopt=0.69; Clmax=1.12.
Stats: 88 W/lb in; 67 W/lb out; 16mph stall; 20mph opt @ 45% (61:34, 47F); 23mph level @ 50% (53:32, 50F); 1029ft/min @ 36.1; -141ft/min @ -4.6.

LHS recommended a 3S1P 11.1v/2100mah 20C LipoESC is a Castle Thunderbird 36 with 36 amps continuos with a 10-7 prop
I am not very knowlegable on electrics, but trying to learn.

Is this a good setup the LHS recommends or not?
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Old Jun 26, 2009, 12:30 PM
Light and floaty does it
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Cambridge, Great Britain (UK)
Joined Sep 2004
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All of the equipment you have is fine itself but with electrics if you change one thing it affects all the others. You can get away with all sorts of combinations of prop, motor, battery and ESC providing every part of the chain is operating well within its limits.

Electrics are fundamentally very different from IC motors. With an IC motor, the bigger to prop the less power you will get as the revs are kept down. With electrics, they all try to run at a given speed for a given voltage, and the load determines the current that they consume. So the bigger the prop the more current the motor will try to pull to achieve the revs that the voltage dictates, and the higher the power you get, until something exceeds its limits and suffers a sudden failure or a slower one through overheating.

The load imposed by a prop depends on far more than the diameter and pitch. Blade shape, thickness and chord also have a lot to do with it. What make of prop have you got?

Assuming it is an APC-E I suspect that combo of prop, motor and battery together will pull significantly more than 30A, which will be pushing the battery harder than I would like to push it, same goes for the speed controller. A 20c battery is theoretically ok for a current that will drain it completely in 1/20th of an hour, which is 3 minutes. For a 2100 mA/h battery that's 42A, which gives you plenty of headroom. However, I don't like pushing a LiPo battery harder than 10C: they live a lot longer that way, and you get reasonable flight times. And if the peak current is anywhere near 36A you could really do with a bigger speed controller. a Thunderbird 54 for example.

One thing you could do is get another identical battery and parallel them together in a 3S 2P configuration, effectively creating a 4200 mA/h unit. That would give you a llot more climbs before you have to recharge, and would enable your batteries to survive a lot more charge / discharge cycles.

If you want to reduce the current a bit, a 10x6 GWS HD will draw less than a 10x7 APC-E and still give you plenty of low speed grunt. You don't need a lot of pitch speed in a Playboy Senior, it's really only a one (slow) speed aeroplane.

If you are going to operate electrics you need something like a Wattsup meter to see what your operating current and voltage are. The safest thing might be to prop down a bit to reduce the current draw and accept slightly less performance. For example, Motocalc predicts that an APC 9x6E prop would draw about 23 amps on that motor / battery, and that's a lot more comfortable for your ESC and your battery. It is still enough to make the aeroplane climb at an estimated 25 degrees climb angle at almost 700 feet per minute. More than adequate performance for most purposes.

I must stress that these are computer predictions and the exact numbers will vary according to individual items of equipment, but the general relationships between them will vary as predicted. If you read this thread:
http://www.rcgroups.com/forums/showthread.php?t=1063477
...you will see that a different user recorded 31.5A draw on a 10x7 MAS prop and 28.5A on the same-make 10x6 prop, for example using a 3S LiPo.
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Old Jun 26, 2009, 02:04 PM
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Indiana
Joined Jan 2005
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I will probably need extra weight in the nose anyway, so an extra battery like you suggested would sound like the best thing to do.
Besides, a Playboy Senior can easily lift the weight, and a little extra wing loading won't hurt a thing, especially in a light breeze, it can penetrate better.
I'll try that route and reducing the prop to a 10/6 or even a 9 something.
LHS owner suggested shortening the prop blades of the 10/7.
You're ideas?
Thanks!
Ed
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Old Jun 26, 2009, 02:30 PM
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Regarding the climb of Fox .35 powered full-size Playboys....good ones get to around 1000 feet in 35 seconds...that's a good bit quicker than the 1000 ft/min predicted by MotoCalc.
It's only important if you're trying to match that performance.
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Old Jun 26, 2009, 03:03 PM
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The motor appears to be a re-badged Himax type. I have couple of re-badged Himax's that seem to be identical to the Eflite-10 - see attached pics. They're Tornado 3120/1000 that are supposed to be 1000kV but I think it's more likely 1100kV.
I have one in an OD self launch glider using Mystery 2650 3s lipos (advertised as 4.2v)and a Graupner 9x5 folding prop. It does at 10800rpm, takes 26amps at 300watts. I also tested it with a Graupner 10x6 folder which does 10000rpm, pulls 34amps at 375watts. I'm using an old Model Motors 40amp ESC.

The model weighs 53oz, wing loading is 9.2oz/sq ft & power bursts are usually only about 30secs before lift hunting then repeating the cycle when the model gets down to about 20ft.
I'd guess that's pretty well how you might want to fly the Playboy ?
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Old Jun 26, 2009, 04:36 PM
Vintage Flyer
Indiana
Joined Jan 2005
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Quote:
Originally Posted by patmcc
The motor appears to be a re-badged Himax type. I have couple of re-badged Himax's that seem to be identical to the Eflite-10 - see attached pics. They're Tornado 3120/1000 that are supposed to be 1000kV but I think it's more likely 1100kV.
I have one in an OD self launch glider using Mystery 2650 3s lipos (advertised as 4.2v)and a Graupner 9x5 folding prop. It does at 10800rpm, takes 26amps at 300watts. I also tested it with a Graupner 10x6 folder which does 10000rpm, pulls 34amps at 375watts. I'm using an old Model Motors 40amp ESC.

The model weighs 53oz, wing loading is 9.2oz/sq ft & power bursts are usually only about 30secs before lift hunting then repeating the cycle when the model gets down to about 20ft.
I'd guess that's pretty well how you might want to fly the Playboy ?

Hi Patmcc,
I asked in another thread on glow to electric conversions, and a guy said the Power 10 isn't big enough.
Yes, I want to be able to climb back up and regain altitue with my Playboy.
Basically fly it for fun.
There is a nice open farm field behind my house, but I am in a nice housing addition, and so I don't want to fly gas. Electric is easier, less mes, less noise.
When it starts to come back down, start th motor up and climb out again, just nice long leisurely flights is what I am looking for.

Ed
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Old Jun 26, 2009, 04:39 PM
Vintage Flyer
Indiana
Joined Jan 2005
1,674 Posts
Quote:
Originally Posted by Flyer1950
Regarding the climb of Fox .35 powered full-size Playboys....good ones get to around 1000 feet in 35 seconds...that's a good bit quicker than the 1000 ft/min predicted by MotoCalc.
It's only important if you're trying to match that performance.
Yes I want the same performance, so my question is, find a more powerful motor or not?
I'm open to suggestion, trying to learn here.
Thanks!
Ed
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Old Jun 26, 2009, 06:21 PM
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Ed, I think a Fox 35 would probably have used a 10x6 prop & the figures I gave for the Tornado motor would probably be a little better than the Fox could manage. Against that the Fox was(is) a very light 35 but maybe needed nose weight to achieve the CG so possibly no advantage over electric there.

As WIP mentioned simply putting a bigger prop on an electric motor can (within limits) be used to adjust power to what you want. A longer version of the same motor or even a similar one with lower kV could be used with a bigger prop to give greater thrust.
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Old Jun 26, 2009, 07:49 PM
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Hi there, Ed.. I'm sure you see by now that there are a million variables as it relates to eletric conversation of vintage planes, from gas to electric. My theory has always been to over-power my models.... I recently did a re-build of an old gas PowerHouse with and 84" wingspan and used en e-flite 46, with 5S 5000 mah Lipo, 80 Amp E-flite , ESC and a 15" electric prop... here are the links to my build and a youtube link to my maiden, the other day...

Sal Taibi 84" Powerhouse Old timer rebuild (2 min 13 sec)


Re-build link -

http://www.rcuniverse.com/forum/m_88...tm.htm#8870345
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Old Jun 26, 2009, 10:06 PM
Vintage Flyer
Indiana
Joined Jan 2005
1,674 Posts
Quote:
Originally Posted by Kholder116
Hi there, Ed.. I'm sure you see by now that there are a million variables as it relates to eletric conversation of vintage planes, from gas to electric. My theory has always been to over-power my models.... I recently did a re-build of an old gas PowerHouse with and 84" wingspan and used en e-flite 46, with 5S 5000 mah Lipo, 80 Amp E-flite , ESC and a 15" electric prop... here are the links to my build and a youtube link to my maiden, the other day...

http://www.youtube.com/watch?v=6DDo0YWcvoQ

Re-build link -

http://www.rcuniverse.com/forum/m_88...tm.htm#8870345
Thanks for the advice.
I'd rather have excess power than not enough!
Nice video of your Sal Taibi Powerhouse!
Great looking old airplane!!!

Ed
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Old Jun 26, 2009, 11:41 PM
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Indiana
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Doing a little research here, and it looks like I'd be much better off withan E-Flite Power 32, and a 60 amp ESC instead of the E-Flite Power 10 and a 36 amp ESC.
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Old Jun 27, 2009, 05:49 AM
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If you want it to go pretty much straight up vertically, yes.
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Old Jun 27, 2009, 03:08 PM
Vintage Flyer
Indiana
Joined Jan 2005
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Bought E-Flite 32 and aCastle Thunderbird 54 amp ESC and will paralell two 20C 2100 mah 11.1 volts lipos
Have a couple props to try, a 10-4.5 and a 10-7
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