Tsybin RSR Mach 3 Reconnaissance Aircraft

Dan Snow

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Hi folks,
This is going yo be a thread on my attempt to scratch build a stand off scale rendition of the Soviet Tsybin RSR Mach 3 Reconnaissance aircraft built in 1959. Only a couple of prototypes were built, and it never achieved proposed speeds because they were not successful getting the proposed ram jets to work.
While working on this build I'm taking the advice of Rob Goring and Steve Heilmann and trying to muddle my way through Open Rocket. After much fiddling and trial and error I have a layout that O R is telling me has a stability of 1.84. Is that good?
Basic description:
Main body tube: BT-55, LOA 30", stern 6" tapers to a BT-50
Motor tube: Designed for a 24mm motor either D or E
Recovery: Parachute
NOTE: It will have a single motor in the main body tube, the wingtip ram jets are for looks only. I can only imagine how entertaining launch could be if two wing tip motors weren't ignited at the same time!
The drop tanks will be for display only, held on by a small magnet for easy removal.
 

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Dan Snow

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According to my latest run through on Open Rocket, this layout has a stability number of 1.84, CG is 2.4" above CP.
I had briefly considered using a glide recovery, but then realized that with the wing loading and the pointy nose cone, it would make a fine spear!!
Once my order from Estes arrives and I procure some card stock from either Staples or Hobby Lobby, I can start construction. Unless someone sees something I missed and need to change.
 

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neil_w

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According to my latest run through on Open Rocket, this layout has a stability number of 1.84, CG is 2.4" above CP.
Is that with or without motors? With motors is the only number that matters.

BTW, if you use the new OR version then you'll be able to model the pods on the ends of the wings and the missiles underneath, which will have significant impact and a bit on CG (probably not so much on CP).
 

Dan Snow

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Is that with or without motors? With motors is the only number that matters.

BTW, if you use the new OR version then you'll be able to model the pods on the ends of the wings and the missiles underneath, which will have significant impact and a bit on CG (probably not so much on CP
I haven't learned how to add the motor yet, need to watch more videos.
Going keep the drop tanks as display only.
 

neil_w

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I haven't learned how to add the motor yet, need to watch more videos.
1) Make sure you have a motor mount defined (second tab on the config panel for your inner tube)
2) Go to "Motors and Configurations" tab, click "New Configuration", and select your motor. Note that this process is a bit easier and more foolproof if you're running the new beta.
3) Add as many configurations as you want, with different motors.
4) Select your largest/heaviest motor configuration in the "Configurations" pulldown, top right corner above the rocket diagram.
5) CG and stability reading will not include he selected motor.
Going keep the drop tanks as display only.
Why? They'll be a bit draggy but otherwise flight-worthy. Would look really nice on the pad.
 

Dan Snow

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1) Make sure you have a motor mount defined (second tab on the config panel for your inner tube)
2) Go to "Motors and Configurations" tab, click "New Configuration", and select your motor. Note that this process is a bit easier and more foolproof if you're running the new beta.
3) Add as many configurations as you want, with different motors.
4) Select your largest/heaviest motor configuration in the "Configurations" pulldown, top right corner above the rocket diagram.
5) CG and stability reading will not include he selected motor.

Why? They'll be a bit draggy but otherwise flight-worthy. Would look really nice on the pad.
Why is simple. I've already built them and the wings as detachable, and don't have enough bits to make new tanks. 😁
 

Dan Snow

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Added an E12 motor and 2oz nose weight. and now have a stability number of 0.598. How bad is that? I can still tweak things around, so what sort of number should I shoot for?
I've moved the wings back 1" and lengthened the body tube by 2" and it moved the stability number to 1.15
 
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BABAR

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Added an E12 motor and 2oz nose weight. and now have a stability number of 0.598. How bad is that? I can still tweak things around, so what sort of number should I shoot for?
I've moved the wings back 1" and lengthened the body tube by 2" and it moved the stability number to 1.15
How does it do on the D?

This looks like a great “show” rocket rather than an altitude seeker. Fly whatever brings you the most satisfaction. Personally if I can get away with say 200 feet on a smaller motor, I don’t see that much more fun in flying it out of sight on a heavier more expensive motor and either walking farther or possibly losing it. But I may be in the minority. If you have a big field and low winds, going big can be a lot of fun too.
 

Dan Snow

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How does it do on the D?

This looks like a great “show” rocket rather than an altitude seeker. Fly whatever brings you the most satisfaction. Personally if I can get away with say 200 feet on a smaller motor, I don’t see that much more fun in flying it out of sight on a heavier more expensive motor and either walking farther or possibly losing it. But I may be in the minority. If you have a big field and low winds, going big can be a lot of fun too.
I read somewhere that I should model it using the biggest motor I planned to use, that way if it was stable with CG above CP, going to a smaller more was supposed to make it more stable rather than less. Tried looking for that post but can't find it right now.
To do list has finding a video on how to run simulations on open rocket, and finding the website I saw listed about determining rocket motor size.
 

neil_w

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I think your numbers look pretty good. Target stability margin is usually 1-1.5 (or maybe 1-2), *or* roughly 10% of rocket length. I would say that with 1.15 on that rocket you're in pretty good shape.

Of course, after it's built you may find that the CG is a bit behind where you expected, and you'll need to add a bit of nose weight to get it back to where you want.
 

BABAR

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I read somewhere that I should model it using the biggest motor I planned to use, that way if it was stable with CG above CP, going to a smaller more was supposed to make it more stable rather than less. Tried looking for that post but can't find it right now.
To do list has finding a video on how to run simulations on open rocket, and finding the website I saw listed about determining rocket motor size.
Good point. If you build it with a wider longer mount and it is stable, you are right, you can consider downsizing the motor. Doesn’t work the other way.

Kinda the opposite of drilling a hole. You can easily make a small hole bigger, much more difficult to make a large hole smaller.
 

lakeroadster

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I read somewhere that I should model it using the biggest motor I planned to use, that way if it was stable with CG above CP, going to a smaller more was supposed to make it more stable rather than less. Tried looking for that post but can't find it right now.
To do list has finding a video on how to run simulations on open rocket, and finding the website I saw listed about determining rocket motor size.

The other option is to ensure nose ballast can be easily adjusted. Then you can optimize that ballast based on the motor you want to use.

If you just add fixed nose ballast for the heaviest possible motor, you limit your choice of smaller motors due to maximum lift off weight for the given motor.


010.JPG X-Wing 001.JPG

Engine Chart 001 Max Liftoff Weight.jpg

 
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