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Old Jan 15, 2010, 07:18 PM
Pusher jets rule!
crxmanpat's Avatar
Mesa, AZ
Joined Jan 2006
17,626 Posts
Build Log
JTechLaser Quick Build SR-71 with simple thrust vectoring - Kits now available!!!

So my friend Jim (eliworm) gave me something he cut out a long time ago, but never got around to building. It's an SR-71 Blackbird built using the same sort of technique like the 6mmFlyRC Quick Build series.

EDIT - Kits are now available for purchase at BMK Designs: http://www.bmkdesigns.net/sr-71-blackbird.html

The elevons include some forward tabs to effect the simple thrust vectoring. Here are the stats:

Wingspan - 23"
Length - 40"
Motor - 2212-6 2200kv
ESC - 30A
Prop - APC 6X4E
Servos - 2x 9g micro servos
Battery - 1350mAh 3S

AUW - 14.5oz

CG - 3"-4" rearward from the tips of the engine inlet cones.

On with the build!

Pat
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Last edited by crxmanpat; Apr 17, 2010 at 03:31 PM. Reason: Kits link added
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Old Jan 15, 2010, 07:20 PM
Pusher jets rule!
crxmanpat's Avatar
Mesa, AZ
Joined Jan 2006
17,626 Posts
The build starts with gluing in the wing spar (5mm OD CF tube), and then gluing the two wing halves together. After the glue set up I added the forward and rear top fuse sections.

For the verticals, angle guides are provided to ensure both are set at the same angle. Before gluing those on I sanded angles on the sections where the vertical fin makes contact with the wing so that there is plenty of contact between the parts for the glue. I then glued them on and taped the angle guides in place.

Next I flipped the plane over and added the forward and rear bottom fuse sections, and the lower engine pods.

Pat
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Last edited by crxmanpat; Jan 26, 2010 at 12:21 AM.
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Old Jan 15, 2010, 07:20 PM
Pusher jets rule!
crxmanpat's Avatar
Mesa, AZ
Joined Jan 2006
17,626 Posts
One of the final construction steps is to add the lower covers for the electronics bay. In order to make the parts fit properly, some angles need to be cut/sanded into the foam both at the center section and at the ends where they meet with the engine pods. I decided to go ahead and paint the inner portions of mine black before gluing them on so that the inside will be black.

After these are glued on, the final steps are to glue on the motor mount to the foam support black, and to attach the assembly to the airframe. And hinge the control surfaces. Before hinging the surfaces I rounded off the leading edges of the thrust vectoring tabs to prevent binding.

Pat
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Last edited by crxmanpat; Jan 16, 2010 at 12:31 AM.
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Old Jan 16, 2010, 12:36 AM
Pusher jets rule!
crxmanpat's Avatar
Mesa, AZ
Joined Jan 2006
17,626 Posts
That pretty much completes the basic construction. All that's left to do are to paint it, add the electronics and go fly!

One thing that I've discovered is that the electronics bay won't be able to contain the lipo as it's too shallow. If I can make CG, I plan to leave off one of the bottom hatches and place the lipo there. If that doesn't work out, I'll have to move it up in front of the bay.

Tomorrow I will play around with the placement of the electronics and try to find a good CG. I'll probably have it all painted as well.

All together I have about 2 hours total into the build so far.

Pat
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Old Jan 16, 2010, 01:29 AM
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triple_b's Avatar
Duarte, CA
Joined Jun 2008
218 Posts
Hey Pat.

Nice build. I've always loved the SR-71. What paint scheme are you planning? I've always wondered what I would do for orientation if I built one of these. Most of the full scale schemes are black and black and black with a little bit of red.
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Old Jan 16, 2010, 09:45 AM
Pusher jets rule!
crxmanpat's Avatar
Mesa, AZ
Joined Jan 2006
17,626 Posts
Black with red trim of course. Never was keen on the NASA schemes.

Pat
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Old Jan 16, 2010, 12:58 PM
Pusher jets rule!
crxmanpat's Avatar
Mesa, AZ
Joined Jan 2006
17,626 Posts
I think this will be the scheme I use. Shouldn't be too difficult as I already have the skunkworks logo.

Pat
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Old Jan 16, 2010, 01:17 PM
You sabotaged my plane.
eliworm's Avatar
Arizona
Joined Jun 2002
2,825 Posts
Pat, you haven't even had it for 12 hours and you'll be ready for a test flight. I should have given you the plane months ago. It sure is nice to see her framed up. If there is any interest I'll post the plan.

Jim
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Old Jan 16, 2010, 01:18 PM
Pusher jets rule!
crxmanpat's Avatar
Mesa, AZ
Joined Jan 2006
17,626 Posts
Jim,

We may need to mod some of the bottom. Let me get the servos and stuff in and we'll see where it all shakes out.

Pat
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Old Jan 19, 2010, 01:02 AM
Pusher jets rule!
crxmanpat's Avatar
Mesa, AZ
Joined Jan 2006
17,626 Posts
OK, I got some time to complete the build tonight. Control surfaces got hinged and control horns added. Glued in the servos, glued on the motor mount and then installed all the electronics so I could try and determine the CG.

I had a brilliant idea to add the angled decks to the top of the plane, and then cut out the frame in the middle so the lipo would fit inside. But it wound up needing to go all the way in front of the angle decks. If nothing else it added a little more body to the plane.

After reading several threads on other SR-71 profile builds, I decided to set the CG initially at the point where the engine nacelles meet the inner wing portion. The pic with the screwdriver shows where I thought I had set it, but it's really about an inch further back from there. It may be a little forward, but that's OK. Like they say, a nose heavy plane flies poorly, but a tail heavy one flies once.

Also managed to get the black paint on as well. All that's left at this point is to reinstall the electronics and go fly. Weather calls for rain through Friday, so I may not get to fly it until sometime this weekend.

Once I get all the electronics installed again I will get some weights.

Pat
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Last edited by crxmanpat; Jan 26, 2010 at 12:26 AM.
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Old Jan 19, 2010, 11:11 AM
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Kangaman's Avatar
North Hollywood
Joined Jun 2006
259 Posts
Be nice to see this up and flying - lookin good Pat..

Paul
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Old Jan 19, 2010, 03:10 PM
Pusher jets rule!
crxmanpat's Avatar
Mesa, AZ
Joined Jan 2006
17,626 Posts
Thanks Paul!

And because you guys keep sending us your lousy weather, I may actually get it decalled up before the first flight.

Pat
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Old Jan 19, 2010, 04:54 PM
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TheTrashMan's Avatar
Joined Jul 2009
803 Posts
i would like plans.It looks like a realy cool bird.
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Old Jan 19, 2010, 05:21 PM
Slow Flyer
Bombay's Avatar
Richmond, TX
Joined Apr 2008
3,236 Posts
looking good. Good luck with the maiden.
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Old Jan 19, 2010, 05:22 PM
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splitpilot's Avatar
trying to catch Mr. FrSky... It flyes
Joined Jan 2005
1,023 Posts
Yes the plans!!!! (los planos)
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