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Building Tips and technical articles. => ARF'S => Topic started by: Mike Alimov on June 16, 2021, 03:10:33 PM
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The Score is a good flyer, I had one powered by Saito 62, and seen other Scores fly well with 60-size combustion engines. But no reports of anyone building/ converting one to electric. My main concern is that the total weight is projected to be close to 78-80 oz due to electric powertrains being 8-10 oz heavier.
Any thoughts?
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Jim Aron did it. I recommend his system.
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Jim Aron did it. I recommend his system.
I'd be interested to hear from him
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Why do you say electrics are 8 to 10 ounces heavier?
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Why do you say electrics are 8 to 10 ounces heavier?
Ok, Crist, maybe not by 8-10 oz, but even 6 oz more is a big difference. I went ahead and weighed ST60 with tube muffler: 14 oz, plus 2oz tank, for a total of 16 oz. For electric system this size: battery TP 6s 2800 mah: 13 oz, motor 7 oz, ESC 2oz, for a total of 22 oz.
So even if the E-Score comes out to 76 oz of all up weight, that's still porkier than most planes that size.
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Mike,
How a the weight of glow fuel added to this?
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Mike,
How a the weight of glow fuel added to this?
Yup, how much fuel for that ST60? Then you can cut that in half to be fair. Don't forget fuel lines and filters too. Also you can calc the amount of oil that stays on the plane during flight.
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Hi Mike
I think you estimate of 8-10 oz for a conversion might be pessimistic, but no matter. Even at 80 oz the power system will not be a problem.
Proved out the biggest Brodak power system on an ARF Strega that weighed in at 80 oz. Motor barely worked up a sweat and the airplane never knew what hit it. Other concerns were nose-heaviness - I thought it was OK but my brothers and nephew all thought it needed a slug of lead in the back. If the Score balanced with the Saito 62, then a heavy outrunner sounds like a smart choice. Because the 80 oz weight was right at the border for .018" lines we put it on .021" - no problem.
The heaviest part (and part with the most weight saving opportunity) of the Strega system was the battery. There are more/better motor & battery choices out there now Here's my thoughts on the Strega set-up and what I would consider today:
* APC 13x5.5 EP (an APC 13x6.5EP would have enabled the next size smaller battery)
* Arrowind 3526 650 kV (BadAss 3530-700kV is heavier but still lighter than the Saito and would help shrink the battery)
* Castle Phoenix 65A (45A would have been plenty but no important weight savings)
* 6Sx2800 at 16 oz (6S x 2200 @12 oz, but again I think there are lighter choices out there)
Not familiar with the front structure of the Score - does it have a firewall with a nose-cone style cowl? If so then it would probably be a chore to use a front mounted motor. On the other hand a nose cone would simplify motor access.
The Strega did not have any meaningful structure at the nose, so I used a rear mount on a 1/4" plywood firewall. I also removed the motor mounts. Used a top side battery hatch, but today I would make it side access to improve battery retention and stiffen the front end. I modified the ARF with a bolt on wing - I understand the Score also uses a bolt on wing? Just the thing for a dad with two sons who fly stunt and a single SUV to get all of them to the contest!
So besides the fact that a 80 oz stunter is a load to hang on to, yes, I think you can get there from here.
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If I remember right the Score had a marginal nose that some times would leave the plane with vibrations of the IC engines. D>K