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Jul 05, 2019, 07:26 AM
Ken's CAD Models
dz1sfb's Avatar
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Quote:
Originally Posted by ruff1
Spitfire is ready...

Build info:
Motor: Suppo BL2208/12
ESC: 10 Amp Heads Up
Battery: GoolRC 900 mah 2S 25C
Prop: 7035
AUW: 10.5 oz
CG: 2.2 inches per the BF109 instructions

Max power: 46 watts @ 7.1 amps - this works out to 70 watts per pound. With wing cubic loading at 9.9 hopefully that will work. Dr. Kiwi shows thrust around the AUW.

I had to put .8 oz in the nose to get the CG right.
Brother, your going to want a 7x6 prop to get the watts per lb up, as well as the desired air speed. That motor is rated up to 16A, which means your only pulling 44% of the power it is capable of producing.

Ken
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Jul 06, 2019, 04:06 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Thanks for the advice. I did some earlier testing, and guess I got confused with the prop I was testing and the results. Those tests had me believing the 7x6 was too much prop with the 10 Amp ESC. I tested a Master Airscrew 7x6, today and it produced 68 watts at 9.6 amps. The connectors got warm but nothing to worry about.

With the AUW of 10.5 oz, that puts me at 105 watts per pound. How does that sound?
Jul 07, 2019, 02:52 PM
Ken's CAD Models
dz1sfb's Avatar
Thread OP
Quote:
Originally Posted by ruff1
Thanks for the advice. I did some earlier testing, and guess I got confused with the prop I was testing and the results. Those tests had me believing the 7x6 was too much prop with the 10 Amp ESC. I tested a Master Airscrew 7x6, today and it produced 68 watts at 9.6 amps. The connectors got warm but nothing to worry about.

With the AUW of 10.5 oz, that puts me at 105 watts per pound. How does that sound?
The 2208 motor is capable of drawing 16A, so it is quite possible to overload a 10A esc.

APC style props seem to give the best bite with the wider blade profile.

Anything over 100 watts per lb. is good. However, loading the motor to its capacity is how to get the most out of any motor without added weight. You should be able to squeeze 130 watts out of that motor, giving you up to 198 watts per lb. You've got a lot of untapped energy.

Ken
Jul 07, 2019, 08:09 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Thanks for the feedback. I'll go with what I have for now.
Jul 27, 2019, 06:32 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Ken,

Maidened today; after dialing in some expo and reducing control surface throws it flew very well. Test pilot really liked the way it rolled, looped and handled inverted flight. A bit too much airplane for me right now, I'll get some buddy box time which should help.

Thanks for a great design sir!
Aug 13, 2019, 07:42 PM
Registered User
Captain Dunsel's Avatar
I have a TBF on the assembly jig, with a Blackburn Skua waiting for the TBF to get out of the jig so it can have it's turn.

Once the Skua is tested (and assuming it survives the test), I'll post the plans. The TBF (from Ken's TBM plan), will have an XT-500 driving the rudder.

I'm looking at some pre-war Skua schemes -- all silver, with roundels on the wing tops. For the TBF, I'd like to put it in star-and-meatball, 1942 colors (but without rudder stripes, if possible!).

CD
Aug 14, 2019, 08:12 AM
Jer. 29:11
jeffsch's Avatar
@Captain Dunsel, the jig is fantastic! Looking forward to seeing your Skua.
Aug 15, 2019, 02:52 PM
Registered User
Captain Dunsel's Avatar
Thank you, Jeffsch, the Frankenjig has been evolving for quite a few years!

Got the control surfaces hinged, the horns glued in, and what I hope will be the final spackling done. Need to finish sand, then paint -- have to go to Wal-Mart and check out the paint selection!

BTW, the fuse & bits in the background are from a box-fuselage SE-5a I started a few weeks ago. It's on hold whilst I finish the two profile jobs for NEAT 2019.

CD


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