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Dec 02, 2008, 06:28 PM
Lee Liddle
Knife Liddle's Avatar
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Discussion

Nitro Planes new SR-71 as a prop jet


These just came out and now the "kit" version is available from Nitro Planes for about $130. It comes with retracts and a pair of 64mm fan units. I will probably put fans in this at some point, but I think it will be fun to do as a prop jet for something quick, easy and FAST.

I have an ARC 28-47-1.5 (2800kv). On 4s it spins an APC 4.75x4.75 at 33k rpm at 60 amps. That`s about 850w and 150mph prop speed. I think that prop will be large enough, but if it isn`t, I can go with 3s and a larger prop.

The retracts are decent quality and I plan to use them.

Here`s a shot of the plane 5min out of the big box.
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Dec 02, 2008, 06:35 PM
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willhaney's Avatar
Beautiful model.
Dec 02, 2008, 07:21 PM
I need more room!
mrblucor's Avatar
Sold out already!

JB
Dec 02, 2008, 07:23 PM
Lee Liddle
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Yeah, I was watching a thread on this plane and someone gave the link when they got the airframe kits. They were sold out in 2 days. They`ll have more though, you can bet on that.
Dec 02, 2008, 11:10 PM
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smkn951's Avatar
don't hold out man....what's the link to just the airframe kits?
TIA
Dec 02, 2008, 11:55 PM
Lee Liddle
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Shure, here`s a link to the airframe only version. It is a little hard to find on their web site.

http://www.nitroplanes.com/sr71bltwened.html
Dec 03, 2008, 04:56 AM
Lee Liddle
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Couldn`t sleep so I decided to put the landing gear on. I installed the steering servo but neither of the actuator servos.

Slick set-up on the steering. Put a drop of lube on the tip of the screws that hold the gear in place before installing them.
Dec 03, 2008, 02:17 PM
Lee Liddle
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Motor installed. It`s a tight fit, but it works.
Dec 03, 2008, 10:30 PM
Flying...Pushing Air Down
sr71fan's Avatar

Ufas


The SR in the photo in the link in post #6 has "UFAS" on the right wing. Too funny! They musta' been in a hurry to get the picture.

Gary
Dec 03, 2008, 11:08 PM
Lee Liddle
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Yeah I saw that. I checked the decals that came with this and they`ve fixed the problem.
Dec 03, 2008, 11:10 PM
Lee Liddle
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Put the nose gear retract servo in this evening. PITA but I`ve got it working now. Just one more servo to mount.
Dec 04, 2008, 10:47 AM
Gravity Fighter
Psycho Synapse's Avatar
Knife Liddle,

Please let us know how it flies as a pusher and if you can post a video...that would be awesome.

cool build,
David
Dec 04, 2008, 12:09 PM
Lee Liddle
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Thanks David. Looks like I may be able to fly it tomorrow. I will do video and a very wordy run down on the flight ect ect LOL That`s just me.

BTW I got the main retract servo in and working. Getting the gear to lock without stalling the tiny servo is tricky. I finally used a little liquid soap to lube the servo arm attachment points and the slide arm on the retracts. That did it. No more buzzing.

I`m doing the final placement on the battery. Should finish it tonight.
Dec 04, 2008, 02:41 PM
Lee Liddle
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Gettin` Close


I decided to put a battery hatch on top. It`s easier to switch packs of course, but since I`m going to run between a 4s3600 and a 4s5000 pack, I don`t want it ejecting out the bottom of the plane as I pull out of my dive.
Lipos would be a nasty ordinance splattered down the middle of the runway.

AUW is right at 3lbs. Watt are about 900 at full stick, and thrust/weight is way more than 1/1. My guess is that thrust/weight is about 1.5/1. I`ll check it on my scale when I get everything buttoned up.
Last edited by Knife Liddle; Dec 05, 2008 at 06:27 AM.
Dec 04, 2008, 06:36 PM
Lee Liddle
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Thrust measurement


I was a little optimistic in my thrust predictions. I measured 1750g of sustained thrust for the 1300g airplane. Approx 1.35/1. That`s with a pitch speed of approx 120mph.

I think it will fly


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