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Aug 26, 2020, 05:52 PM
Ghost Rider the pattern's full
santanig5's Avatar
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Question

Old "Sportster "? Conversion Questions


Greetings,

I've had this old glow plane for more than 20 years, never flown, but I've been flying electric for the past 5 years and am ready to try to convert and fly it.



LOA: 48"

Wingspan: 62"

Weight: 4 lbs airframe only, 6 1/2 lbs with motor, esc, 5000mAh 6S battery.

Power: Millennium PRO 65 glow.

Prop: 12x7



I have a donor power system from a old FMS 1400mm Pitts, 6S.



Wingspan 1400mm / 55.1in

Length 1297mm / 51.1in

Flying Weight 3300g / 7 1/4lbs.

Power System 5060-Kv360 Brushless Motor

Speed Control 85A ESC, Internal 5A SBEC

Propeller 14x8, 3-blade propeller with spinner

Required Battery 22.2V 3300mAh 25C 6 cell LiPo



Will this power system suffice?
Last edited by santanig5; Aug 28, 2020 at 08:37 PM.
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Aug 26, 2020, 07:04 PM
San Antonio TX.
sensei's Avatar
Yes it will fly it around, I donít believe it will be allot of power per say, but if you are just going lazy fly, it should be fine.

Bob
Aug 27, 2020, 12:27 AM
Registered User
scirocco's Avatar
I see you posted the prop is 12x7. Is that the biggest that will fit or what the glow engine used?

With 6S and only 360 rpm/V you would want a 14x10 prop to achieve the 100W/lb benchmark for a sport model.

If 12" is the max, then it is a marginal setup compared to glow power. 12x10 on 6S will give you only 450W. Flyable but limited aerobatic capability.

You could achieve .60 glow performance with that motor and a 12" prop if you were willing to use 8S voltage, ie 4S + 4S in series or 6S + 2S, but that would require a high voltage esc.
Aug 27, 2020, 06:08 AM
Ghost Rider the pattern's full
santanig5's Avatar
Thread OP
Quote:
Originally Posted by scirocco
I see you posted the prop is 12x7. Is that the biggest that will fit or what the glow engine used?

With 6S and only 360 rpm/V you would want a 14x10 prop to achieve the 100W/lb benchmark for a sport model.

If 12" is the max, then it is a marginal setup compared to glow power. 12x10 on 6S will give you only 450W. Flyable but limited aerobatic capability.

You could achieve .60 glow performance with that motor and a 12" prop if you were willing to use 8S voltage, ie 4S + 4S in series or 6S + 2S, but that would require a high voltage esc.
Both, what it came with and what will fit with about 1 1/4" clearance.
I think I'll hold off on this for now, it looks like I'm going to have to buy a motor like a rimfire. 60 for this to fly like a sport plane on 6S and don't have the money to invest at this point.
Not really feeling 8S.
Latest blog entry: FMS F4U-4 Corsair V3 1400mm PNP
Aug 27, 2020, 07:56 AM
Registered User
scirocco's Avatar
Makes sense.

Personally, I think the Rimfire 60 Kv is a little too high for useful sized props on 6S

The Rimfire 80 is the same size, just lower Kv that IMO is better suited to a 12" prop on 6S. 12x8 should be about 800W which would haul. The Leopard LC5065-5T with Kv between the Rimfires could also be worth a look - and a more reasonable price.

I'd be assessing balance with whichever pack you want to use and looking for motors with Kv between 480 min and about 550 rpm/V that best help balance, although there don't seem to be many reasonably pried motors above 480 rpm/V and above 400g. The motor search tool in ECalc (subscriber version, desktop mode) is invaluable for finding comparable motors
Aug 27, 2020, 08:56 AM
Ghost Rider the pattern's full
santanig5's Avatar
Thread OP
If I'm reading the G.P. site correctly the .80 says "Power System Recommendation60 Amp ESC, 6S LiPo, 15x6 to 15x8 Electric Prop"

While the .60 says "Power System Recommendation60 Amp ESC, 6S LiPo, 12x6 to 13x4 Electric Prop"
Which is right where I am.
Guessing I can go with a .46 if I want a little more prop clearance?
"Power System Recommendation60 Amp ESC, 6S LiPo, 10x5 to 11x5 Electric Prop"
Latest blog entry: FMS F4U-4 Corsair V3 1400mm PNP
Aug 27, 2020, 05:42 PM
Registered User
scirocco's Avatar
Quote:
Originally Posted by santanig5
If I'm reading the G.P. site correctly the .80 says "Power System Recommendation60 Amp ESC, 6S LiPo, 15x6 to 15x8 Electric Prop"

While the .60 says "Power System Recommendation60 Amp ESC, 6S LiPo, 12x6 to 13x4 Electric Prop"
Which is right where I am.
Guessing I can go with a .46 if I want a little more prop clearance?
"Power System Recommendation60 Amp ESC, 6S LiPo, 10x5 to 11x5 Electric Prop"
IMO those recommendations are re not entirely realistic

If you put a 12*6 prop on a 650 rpm/V Rimfire 60 you'll be pulling something like 1250-1300W. A) way more than you need, B) a lot of power for a ~360g motor C) you'd want bigger than a 60A ESC.

The Rimfire 46 recommendation is downright ridiculous. An 11x5 prop on 6S is going to pull about 1400W, way too much for a 268g motor.

If you want to run 10 or 11" props I think of the Rimfire, the 60 is the better option - about 750W with 10x6 and 1050W with 11*7.

For a sport (ie not 3D) model, don't be afraid to add pitch to tailor your power and thrust if adding diameter is not feasible or is too big a power increment.
Aug 28, 2020, 07:55 PM
I just want to go fly!
walter3rd's Avatar
FYI I have been flying my ss 60 with a 13x8 prop on 5s and it’s a great flying plane.i can’t remember what motor I have but it’s smaller than a power 60 for sure. Plenty of power to sport fly and my go to after time away. Fantastic plane. Good luck. Scirocco knows his stuff and has helped me many times before. Thanks. Walt ps- mine was built from a kit and was only used as electric. All my kits are designed for fuel but I just fly electric myself
Oct 28, 2020, 04:43 PM
Ghost Rider the pattern's full
santanig5's Avatar
Thread OP
Well, it's been a while, but I think I'm ready to maiden this plane.
I asked a buddy to cut the hatch, he took his time, but did a beautiful job.
She is a tick over 5 lbs. Without battery.
I'm probably going with my HobbyStar 6S/4200mAh/40c @495g, I don't think I'll get a decent CG with anything larger.
It's about 2 1/4" from the leading edge now, of course I have no idea where the COG is on this plane.
Motor and prop are the same, 85A FMS ESC that came with the motor from the Pitts.

Thoughts?
Latest blog entry: FMS F4U-4 Corsair V3 1400mm PNP
Oct 29, 2020, 03:18 PM
I just want to go fly!
walter3rd's Avatar
Good luck
Oct 29, 2020, 08:45 PM
Balsa Flies Better!
I think your cg is too far forward- perhaps Walter can chime in with where his airplane's cg is? I have no idea about your power system at this point, but on a 5 lb airplane, 6s might be a bit much. Like I've said before- a watt meter is your friend...

Sam
Oct 30, 2020, 07:17 AM
I just want to go fly!
walter3rd's Avatar
mine fly's great on 5 s and she's no lightweight. just fyi.
Oct 30, 2020, 01:23 PM
Ghost Rider the pattern's full
santanig5's Avatar
Thread OP
Quote:
Originally Posted by Megowcoupe
I think your cg is too far forward- perhaps Walter can chime in with where his airplane's cg is? I have no idea about your power system at this point, but on a 5 lb airplane, 6s might be a bit much. Like I've said before- a watt meter is your friend...

Sam
yep, I'll definitely check it, however the doner plane was 7 1/4 lbs. but it did have a larger 3 blade prop.
Latest blog entry: FMS F4U-4 Corsair V3 1400mm PNP
Nov 02, 2020, 05:57 PM
Registered User
I just converted a glow powered Great Planes Super Sportster that a cousin gave me. It was set up for a .60 glow. When I cut the nose off, there was a big blob of clay packed behind the firewall. So I extended the nose to make it like a turbine powered aircraft. Power is a Tacon 60 on 6s. Prop is a Master Airscrew 12/8 3 blade drawing 39 amps. Flies pretty well. I am moving the c/g slowly back till I find the sweet spot
Nov 02, 2020, 08:20 PM
Ghost Rider the pattern's full
santanig5's Avatar
Thread OP
Quote:
Originally Posted by warbird51
I just converted a glow powered Great Planes Super Sportster that a cousin gave me. It was set up for a .60 glow. When I cut the nose off, there was a big blob of clay packed behind the firewall. So I extended the nose to make it like a turbine powered aircraft. Power is a Tacon 60 on 6s. Prop is a Master Airscrew 12/8 3 blade drawing 39 amps. Flies pretty well. I am moving the c/g slowly back till I find the sweet spot
Sweet
Latest blog entry: FMS F4U-4 Corsair V3 1400mm PNP


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