Blackburn Skua, FF to RC conversion of Earl Stahl design - Page 6 - RC Groups
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Dec 28, 2012, 03:33 AM
Registerd Beaver
Smokin' Beaver's Avatar
Looking good Dave.
If I may offer some advice should it be sluggish in response, the gaps between the surfaces may allow airflow to pass between them. To fix that a small strip of tape across the gap may fix it. Of course add the tape to the upper side of the surface when it is deflected down to allow movement of the surface.

How much does she weigh in at? Looks quite light to me,

- Phil
Dec 28, 2012, 05:32 PM
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davidterrell80's Avatar
Thanks for the idea, Phil. I've pondered the gaps. Part of me wonders if the Reynolds numbers are so low here that the gaps would not matter. I'll err on the side of caution and seal the gaps.

She is still under 200 g, but I have not added the motor, ESC or Rx.
Latest blog entry: Remembering Bob Hoover
Jan 04, 2013, 10:30 AM
Registered User
Love the build!
Jan 04, 2013, 07:19 PM
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davidterrell80's Avatar
Thanks. In the "sport scale" spirit of my build, I decided to use rubber bands to attach the wing. The wing-fuselage saddle is done, the servos are in, and the pushrods are set. I did have to add guides at mid rod to control the flex in the pushrods, even though they were carbon. I just chose rods that were a little thin.

This weekend is dedicated to installing the motor, ESC and receiver; and, mocking everything up for a CG check and locating the battery.
Latest blog entry: Remembering Bob Hoover
Jan 04, 2013, 11:13 PM
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davidterrell80's Avatar
I decided to push on a little. I created the roundels in a Powerpoint, printed them on bond paper, cut them out, used spray adhesive to attach them, and laid down some clear packing tape to protect them. The markings on the vertical fin are colored packing tape.

Like I've said before, this is sport scale. As long as she looks good at 20 meters with one squinky eye, I'll be happy.
Latest blog entry: Remembering Bob Hoover
Jan 06, 2013, 05:24 PM
The "pro" in procrastination
Steve85's Avatar
She really looks the part now, David. Did you get around to building your vac former?

Steve
Jan 06, 2013, 08:57 PM
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davidterrell80's Avatar
Hey Steve,

No, not yet.

I've decided to leave the forward canopy to the very end. Then, if timing is tight to achieve first flight before the end of the contest cycle, I can make a temporary forward canopy by flat-patterning it and folding it to shape.

This evening, I've cobbled together the power system and bound the Receiver. Tomorrow, I hope to get the motor mounting finished and installed; and, mount the motor on a test stand with a watt meter hooked up.
Latest blog entry: Remembering Bob Hoover
Jan 07, 2013, 01:37 PM
Slip the surly bonds...
Sopwith Mike's Avatar
Quote:
Originally Posted by davidterrell80
As long as she looks good at 20 meters with one squinky eye, I'll be happy.
Well, I have one squinky eye (seeing the man tomorrow) but she looks pretty good to me!
Jan 07, 2013, 07:00 PM
Heads up...
RMCCOR7737's Avatar
Quote:
Originally Posted by Sopwith Mike
Well, I have one squinky eye (seeing the man tomorrow) but she looks pretty good to me!
I got my squinky eyes fixed last week...LOL It still looks good to me...the plane has a real peculiar design doesn't it?
Jan 07, 2013, 08:03 PM
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davidterrell80's Avatar
My Navy callsign was "Popeye".. thus, the squinky eye remark.

When I saw the plan, I thought, "Was there ever a better plane designed for Rubber-powered flight?"

As for the real plane:

-- The long nose, putting the mass of the engine and the fuel tank far forward, relative to the center of gravity should make a terminal-speed dive stable; e.g. the lawn dart effect.

-- The vertical stab being moved forward, so it would not be blanked by turbulence shed by the horizontal stab in the moments just after a high-speed pull-out begins and AOA is high; just like modern fighters.

-- It even had an anti-spin drogue chute in the tailcone, telling me the clean CG was pretty far aft; so it could be very maneuverable in pitch, once the bomb was dropped.

-- Then, there were several watertight compartments, in the aft fuselage and the (apparently) dry wing, to make ditching more survivable.
Latest blog entry: Remembering Bob Hoover
Jan 07, 2013, 08:11 PM
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davidterrell80's Avatar
I finished the motor installation. I had to rip out the firewall, once, after I mis-measured... mis-cut... something happened and the motor was sticking out of the cowl about 0.5 cm too far.

But it's fixed now.

Once I place the ESC and Rx in the fuselage, lay in some hooked fastener for the battery, test everything with the watt meter, and set up the radio it will be time to turn my attention to the canopy.

To vacuum or not to vacuum...
Latest blog entry: Remembering Bob Hoover
Jan 07, 2013, 08:42 PM
Heads up...
RMCCOR7737's Avatar
Quote:
Originally Posted by davidterrell80
I
To vacuum or not to vacuum...
Vacuum,vacuum,vacuum,vacuum,.....
Jan 08, 2013, 12:44 PM
Registered User
conrad907's Avatar
I would think with those strip ailerons, response should be very good David. Anxious to see it in the air. Looking great!
Jan 08, 2013, 10:02 PM
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davidterrell80's Avatar
Mounted an EMAX CF 2822 motor from Heads Up RC.

1300Kv
Cburst = 16A

The 3S suggested prop was EP8040 which was supposed to draw 12 A and produce 24 ounces of thrust. (3S at 12 A makes for just under 150 Watts)

I tested the setup WOT with a 3S 800mAh 25C battery and got 80W at 7 A.... on the specifications page, Heads Up implies they used a 30C battery for their test. Would the difference be so much?

Working my spreadsheet... I see that 80 watts works out to be 100 W/lb... about trainer performance.

I use these same batteries in my Nakajima Rufe and was considering it under powered.

Must think about this.
Last edited by davidterrell80; Jan 09, 2013 at 11:38 PM.


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