Star Orbiter G80T...Supersonic?

Discussion in 'Mid Power Rocketry (MPR)' started by ebman159, Jul 23, 2019.

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  1. Jul 23, 2019 #1

    ebman159

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    I was curious if In ideal conditions could a Star Orbiter Rocket go supersonic? I don’t have RockSim, therefore I could only guess about the drag coefficient to calculate how much force I’d need. I think I need around 86 Newtons with little to no humidity(which let’s be honest when does that happen) at the elevation I’m at. I know G80Ts can surpass 100 Newtons at their maximum thrust but I know that’s not the average. I have flown rockets quite a bit, and I’m pretty good at designing and building my own rockets, so I could build one to go supersonic, But I wanted to see if I could maybe push my beloved star Orbiter to hit and surpass the speed sound. If anyone could help me out with info that’d be amazing!
     
  2. Jul 23, 2019 #2

    Donnager

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  3. Jul 23, 2019 #3

    ebman159

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  4. Jul 23, 2019 #4

    Nytrunner

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    Couple things:
    -Fins. Reinforce them somehow. I recommend replacing with Basswood, or at least skinning them with 1/32" basswood.
    -Surface finish. The smoother it is, the faster/higher it goes. Balancing act between weight and added finishing material
    -Recovery. These are intended to be recoverable. Any idea how you'll find it?
     
  5. Jul 23, 2019 #5

    ebman159

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    I have a chute release system that seems to work well when I launch with G40s. I was planning on outfitting it with that and then also altimeter three so I could prove I hit supersonic. Would this be sufficient? I’ll be launching at a local airstrip. Second of all, would replacing the fins or skinning them be easier/more effective. Third, I have sanded my paint and primer on the rocket with increasingly finer grains of sandpaper and it’s really smooth...is this what you were referring to?
     
  6. Jul 23, 2019 #6

    Nytrunner

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    The Chute release will help, and the Alt3 will give good data. Try and secure it in the PL bay so it's vertical axis aligns with rocket (although if it blinks out of site and you can't see it, then you have to hunt for 230$)
    Either or, that's up to you. Anything is better than straight balsa.
    Yep, sounds like you've got finish handled
     
  7. Jul 23, 2019 #7

    ebman159

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  8. Jul 23, 2019 #8

    Wallace

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    Hint: The body tube is the weak point after upping the fins with basswood. Stock built (well built) it''ll handle a G 80..Anything more is up to the prevailing winds..Do a search...
     
  9. Jul 23, 2019 #9

    Nytrunner

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    Gotcha

    So the Alt 3 takes acceleration data in 3 directions (axis) along it's length, side, and top/bottom. When it's shaking around loose, it has to interpret the movement data from all three directions to give you your results. It's really good at doing this, but it's cleaner if you fix it in place. A little balsa sled and ziptie in the payload bay is lightweight and could serve nicely.

    upload_2019-7-23_17-27-6.png
     
  10. Jul 24, 2019 #10

    ebman159

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    Yeah I tested my tube on a scale, putting down about 110 Newtons of force which would be about the maximum amount of thrust. The tube I have had a wrinkle to start with, but I’ve launched it a few times and it hasn’t been an issue...the tube hardly wrinkled at all under the pressure but I think I’m just gonna buy another kit and start there...then I can do everything right from the start. In the event I can’t get another one, anyway to strengthen the tube to keep it from wrinkling further?
     
  11. Jul 24, 2019 #11

    ebman159

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    Sounds good! I didn’t know if you would know...any estimate on how high a G80 would go in this rocket...? I have put a G40 in it and got 2,189 feet out of it.
     
  12. Jul 24, 2019 #12

    Nytrunner

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    A G40 has ~115 N-s (Newton seconds) of impulse, a G80 has ~135 N-s. So about that much higher if all else is equal.

    Although the G80 burns much faster, producing higher thrust, pushing your rocket faster, and creating more drag, so that will reduce the final altitude slightly.
     
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  13. Jul 24, 2019 #13

    ebman159

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    Well thank you! That is extremely helpful information.
     
  14. Jul 24, 2019 #14

    Charles_McG

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    Paper tube is surprisingly tough. I've put BT55 under 100 pounds of compression. (118 at the failure, IIRC) I think weight will be your enemy. Take a look at Apogee's Aspire. Takes a G80 to put it over Mach 1 and it's built -light- and minimal recovery.
     
  15. Jul 24, 2019 #15

    ebman159

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    I took a look at the Aspire but I want to retrieve my data to be able to confirm Mach speed. I don’t have a GPS tracker, nor do I have the money for one, and I am not confident I will find the Aspire if I put a G80 in it...I’ve heard stories. The math checks out for Mach speeds for this rocket but you might be right about the weight.
     
  16. Jul 24, 2019 #16

    Wallace

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    Agreed: But this is 2 tubes and a coupler. I've shredded one, although it took a bit more than a G...
     
  17. Jul 24, 2019 #17

    Theory

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    i highly doubt you will hit mach with a Star Orbiter using a G80. It will be an exciting flight to be sure

    FWIW, a quick run through thrustcurve (which i consider a "back of the envelope" calculation and nothing more) using a weight of 6oz w/o motor and a drag coefficient of .6 shows that a G80 will hit 1,061 ft/sec. and really, when you factor in summer humidity, actual drag from the fins (airfoil on the leading and trailing edge) any overhang of the motor retainer etc. hitting mach with a G is even more unlikely.

    not to worry though, a DMS H182 shows 1,604 ft/sec (well over mach). i have one sitting in the range box for just such a project :)
     
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  18. Jul 24, 2019 #18

    Wallace

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    Now that's interesting. Please let us know how it works out. I've "heard" it's been done, my attempt was not successful, as in it came down in small pieces...
     
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  19. Jul 24, 2019 #19

    ebman159

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    Yeah I know it’s highly unlikely. I will modify the rocket to give it the best chance possible, but I think I’m with ya, I don’t know if it’ll make it over Mach 1.
     
  20. Jul 24, 2019 #20

    Theory

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    will do, though to be 100% honest, the true intent of the H182 is to really push my Aerotech Arreaux

    the Estes Star Orbiter has always been on my "want" list as i like the lines and have a soft spot in my heart for the Estes BP motors. historically i have flown more of them than any other type and still find them fun.
     
  21. Jul 24, 2019 #21

    Wallace

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    Yup, something about b.p. motors is just cool...
     
  22. Jul 24, 2019 #22

    Theory

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    RIGHT?!

    not sure if this is appropriate to mention here, but do you remember the old school Silver Streak motors? by they were exciting - when they worked and when they didnt ;-)
     
  23. Jul 24, 2019 #23

    ebman159

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    Wow. I like the look of the Arreaux. That’ll be exciting. The way I see it, whether I hit supersonic or not, the goal is for me to push this thing’s limits without doing much modification to it and without getting an HPR license. If and when I get my HPR, I’ll begin to experiment more...I think the star Orbiter is a good kit to experiment with personally. I’m sure there’s better but the simplicity and cheap cost of the kit makes it good in case you think might not get it back or get it back in one piece.

    Have fun with that H182 though!! That’ll be fun!
     
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  24. Jul 24, 2019 #24

    Wallace

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    I've heard of Silver Steak motors, but never seen them..
     
  25. Jul 24, 2019 #25

    Wallace

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    The real beauty of the Star Orbiter is the price w/Hobby Lobby discount, light weight and 29mm mmt..Opens up a lot of room to experiment without breaking the bank. I'd say that under the right conditions you can accomplish what you want. I've "pulled off" quite a few things others said would not work. You'll never know unless you try.
     
  26. Jul 24, 2019 #26

    ebman159

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    YESSS!!! Hobby lobby rules for that...I can get F-15 engines for cheap that way too. But I understand it could work, and I understand it might not. But as you said it best, I’ll never know until I try. From what I understand, as long as the conditions and build are perfect, all should go well.
     
  27. Jul 24, 2019 #27

    Wallace

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    That's the correct attitude. Best of luck and don't forget to share results.
     
  28. Jul 24, 2019 #28

    Theory

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    to the OP, if you are looking to "stress test" your build without using cert-1 HP motors, I would suggest trying a G76. yes you need to purchase some hardware, but that thing is one sledgehammer of a G motor. 149N right at the hit (41N more than a G80 and DOUBLE that of a G40)! i can tell you it picked up my 49oz minnie magg like it was nothing. ...and that is saying something, especially with the minnie magg having the same aerodynamic properties as a fridge!
     
  29. Jul 24, 2019 #29

    Wallace

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    Just remember, mass is your enemy when looking for max velocity. Not necessarily so when attempting max altitude..In other words, keep it light..
     
  30. Jul 24, 2019 #30

    ebman159

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    I’ll look into it. Thank you for the info!!
     

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