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Hobby Lab SR-71

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U812

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Stumbled over this in the garage in the old bone yard. Never did fly it as a rocket but I did as an electric pusher and it was blindingly fast. I retired it a couple of year ago but it's still in good shape.

So. How do I get it to fly as a rocket again?

Found the old instructions on line. Something about an E-15-P motor. Seems I'll need an bigger launch pad and a 12 volt system. But I worried the motor might be hard to come by?

I saw a few videos of it flying as a Rocket. It flew very well.

Also does anyone now were to find a scan of the decal? Mine could stand to be replaced.

Thanks for any help, links and info on this bird.

Steve

SR.jpg
 

powderburner

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If that's an Estes E15 that you're supposed to use, those are loooong gone (discontinued due to little problems like CATOs)

If the next choice is a plugged Estes E9, I don't think those exist either.

If they meant a composite E15 (aerotech?) I guess you could use a RMS and load some sort of plug in place of the delay grain...

Let us know what you find? (that works)
 

sj_h1

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Stumbled over this in the garage in the old bone yard. Never did fly it as a rocket but I did as an electric pusher and it was blindingly fast. I retired it a couple of year ago but it's still in good shape.

So. How do I get it to fly as a rocket again?

Found the old instructions on line. Something about an E-15-P motor. Seems I'll need an bigger launch pad and a 12 volt system. But I worried the motor might be hard to come by?

I saw a few videos of it flying as a Rocket. It flew very well.

Also does anyone now were to find a scan of the decal? Mine could stand to be replaced.

Thanks for any help, links and info on this bird.

Steve
I have the Estes decal sheet if that help. The resolution is too high to post here. If you want them, sent me an email address an I will email them to you if you want.
 

bcanino

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If that's an Estes E15 that you're supposed to use, those are loooong gone (discontinued due to little problems like CATOs)

If the next choice is a plugged Estes E9, I don't think those exist either.

If they meant a composite E15 (aerotech?) I guess you could use a RMS and load some sort of plug in place of the delay grain...

Let us know what you find? (that works)
No, Not Estes, Aerotech and you can still get the E15-P from Value Rockets
I doubt that a E9 will get the SR-71 off the pad.
 

U812

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Thanks guys for all the help and responses. It was a real trip to fly as a RC plane but I never did like the prop at the back. No SR should ever be flown on a prop it's just not right! ;)

Steve
 

jadebox

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Found the old instructions on line. Something about an E-15-P motor.
I have some of the E15-P motors. They are the old-style Aerotech E15 motors with no ejection charge. You can probably find someone with a bunch of the old-style E15's from which the ejection charge has escaped. Just plug up the little hole on top and you'll have an E15-P.

-- Roger
 

georgegassaway

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The E11-P reload for the 24mm “R/C” case is really ideal for the SR-71. The E11-P reload did not exist when the SR-71 first came out.

Two things about that. For one, you need to have the 24mm R/C casing. And the other thing is that since the R/C case weighs more, you’d need to add a bit of noseweight to help to keep the glide CG in the right range.

Otherwise yes, the Aerotech E15, plugged, is the way to go. Even if the Estes E9-P was still made, the E9’s thrust is a bit too wimpy for the SR-71. And it only is about 27-28 N-sec, while the E11 and E15 are close to 40 n-sec.

BTW - a link I ran across:
http://homepage.mac.com/srogers4/rockets/gliders/sr-71/

- George Gassaway
 

U812

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Thans guys this is a big help!

Steve
 

Serenity

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I have a HobbyLab SR-71, and I have flown it on an Aerotech reloadable F12 and also an E18. These two reloads are for the regular 24/20-40 RMS casing which has the delay element cap with the ejection charge well. I assemble the reload per instructions, I simply don't put any black powder in the ejection well. Since you aren't really employing the ejection charge, it doesn't matter what delay time you use. BE SURE to use the delay element, I wouldn't substitute wadding or anything like that (not to mention I'm pretty sure that substituting wadding for a delay element would constitute illegal modification to a commercial engine at a sanctioned TRA or NAR launch).

VERY IMPORTANT - as George said in his post, make sure that you check the balance with whatever motor you plan on using. This bird is pretty sensitive to having the proper CG. Some of these birds were also bad about the radio components coming loose inside during boost or a rough landing, which can radically change the balance, which ends up being bad news.

I've had a couple of people tell me that they couldn't fit the regular 24mm AT RMS casing in their HL SR-71 motor mount, but it works fine in mine. Perhaps there were manufacturing variances that prevents that casing from working in some of them. If you decide to try this, I'd check the fit before going to the field.

The F12 is an interesting motor for the bird, as it leaves a long black smoke trail for the BlackBird. Looks neat. The E18 motor will come close to duplicating the performance of the single use E15PW Aerotech motor - they are very close as far as thrust characteristics.

It sounds like you have a fair amount of RC experience, and you say you flew the SR-71 with a pusher prop power plant (say that real fast 3 times). The only thing you want to remember is that with a glider, and particularly a delta variant glider, you can bleed speed really fast in a turn. I've had that happen with the HL SR-71. Pull a hard turn with it at low speed, and part way through the turn it's quite likely to stall and snap on you. To turn this bird, I always do one of two things - go into a shallow dive prior to the turn to build up sufficient speed, or make sure that I let it descend in the turn so that it will maintain speed. I don't recommend any sharp turns unless you have plenty of altitude.

It is a fun and interesting model to fly, and it always attracts attention at a launch.
 

U812

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Serenity,

Thanks for all the detailed info!

KPM61,

Thanks very much but I finally got them.

Steve
 
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