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Converting the Super Flyin' King to electric?

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Old 05-02-2004, 11:39 AM
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Lance42
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Default Converting the Super Flyin' King to electric?

I'd like to get people's opinions and ideas for converting the [link=http://www.btemodels.com/sfk.html]Super Flyin' King[/link] to electric.

Its wingspan is 11ft (3.3m), its weight is about 33lbs (15kg), and it's usually fitted with a 50-80cc gas engine. This plane is a good choice for me due to its large payload capacity (up to 20lbs/9kg) and large cargo area.

I'm intending to use the plane for a commercial project. It'll be used to carry a gas analyzer for making airborne C02 measurements. The analyzer weighs about 4lbs (1.8kg) and I'm guessing that the batteries will weigh another 6-8lbs (2.7-3.6kg). So I'm looking at a total flying weight of about 44lbs (20kg).

I'd prefer to fly electric to avoid various issues with fuel (mess, engine maintenance, fuel vapour contaminating the measurements, etc). Plus my experience is with electric, albiet with smaller planes. I won't be doing any aerobatics, just flying level at one altitiude (say 100m) and making gentle turns. I'd be flying at the minimum cruising speed most of the time (about 25mph/40kph). Also, I'd like to get at least 30 minutes of flight from a single battery charge (hence the high battery weight).

So is e-conversion feasible with this plane? Assuming it is:

- What power motor should I use, I assume at least 2000W?

- Does anyone have experience with 'Torcman' motors or 'Flyware T-Rex' motors? Both these brands are the outrunner brushless type, and have 2000W+ models available. Any other motor suggestions?

- What prop size would be best? I'd prefer to direct-drive the prop. I need to fly fairly slowly and I have to use battery power efficiently.

- As for batteries, I guess I'll go with LiPo, say a 10s10p pack or something ridiculous like that. Opinions? Cost isn't a big worry for this project. Battery maintenance/charging might be a b*tch though

- The Super Flyin' King can also be fitted with twin motors. Does anyone have experience with using twin electric motors, say 1000-1500W each?

- If it all gets too hard and I decide to go with gas, how much hassle is gas? I've never had a gas/glow plane so I've go no way to compare it to e-flight. Is gas less messy that glow?

Thanks for reading - I'd really appreciate some input.
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Old 05-03-2004, 08:05 AM
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Greg Covey
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Default RE: Converting the Super Flyin' King to electric?

Holy cow! You Aussies sure make things big down under! We recently had a very large fast ferry from Katz delivered from Australia to New York via water on its own power...also very impressive!

My first recommendation would be to consider the twin motor version of the Super Flying King. Two smaller motors are more efficient than one larger motor and you just might get away with some existing motors currently on the market without doing any custom work.
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Old 05-03-2004, 08:28 AM
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Matt Kirsch
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Default RE: Converting the Super Flyin' King to electric?

At 2000 Watts, <50 Watts per pound will leave you with a sour taste in your mouth. 3000 Watts, and you're starting to talk turkey.

Check out that 35% Extra project described in this forum a few weeks back. That'll give you an idea of the kind of battery pack you're looking at in a 3000-4000 Watt application.

No single motor on the market will give you the power, so you'll definitely need to go twin. The 35% Extra has twin motors belt driving a single output shaft. Evidently, there's a twin motor version of the SFK, so you could go that way too.

Prop size... I like Gary Wright's philosophy: Start out with the biggest diameter prop you can fit on the plane.
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Old 05-11-2004, 07:49 PM
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Default RE: Converting the Super Flyin' King to electric?

You might want to reconsider the gas option. My 3W-75 powered SFK with cannister muffler (same setup as Bruce Tharpe's prototype) is the cleanest airplane I've ever owned. No mess whatsoever. There is really nothing to clean up when the flying is done and the exhaust tube points straight down. There is no comparison to a glow engine at all. You could easily modify the muffler with a longer exhuast tube say 6-12 inches long well out of the way of your testing equipment. With a 50 ounce tank it would easily coast along for 30 minutes. Afer 10 minutes, the 40 oz tank on mine is still 2/3 full. Mine weighs 41 lbs and the power is perfect for this airplane and quiet too. Good luck.
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Old 05-12-2004, 05:49 AM
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Default RE: Converting the Super Flyin' King to electric?

Thanks for the info Bob! It's good to hear from someone who has experience with the SFK. I may be able to use a smaller plane now (I found a smaller instrument), but if I do go with the SFK I'll definitely consider gas. Mess and contamination were two of my big worries.
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