I800 insanity

Discussion in 'Propulsion' started by watermelonman, Dec 30, 2015.

Help Support The Rocketry Forum by donating:

  1. Dec 30, 2015 #1

    watermelonman

    watermelonman

    watermelonman

    Well-Known Member

    Joined:
    Sep 22, 2014
    Messages:
    2,559
    Likes Received:
    0
    Anyone flying the I800 on relatively thin rockets? I have a larger rocket that loves the K2045, and the rocket in question has done quite well on I566 and I540, but I was shocked to see the I800 simulation showing so much more acceleration than even these other crazy flights.
     
  2. Dec 30, 2015 #2

    3stoogesrocketry

    3stoogesrocketry

    3stoogesrocketry

    Well-Known Member

    Joined:
    Feb 26, 2012
    Messages:
    1,127
    Likes Received:
    61
    Your total impulse is so much lower , you will not see the same speeds as the I540.

    Eric
     
  3. Dec 30, 2015 #3

    COrocket

    COrocket

    COrocket

    Well-Known Member

    Joined:
    Oct 28, 2009
    Messages:
    817
    Likes Received:
    0
    What's a "thin" rocket? I'm assuming close to minimum diameter? If it has done well on an I540 then it should do fine since the I800 is less impulse. Normally it's speed that destroys rockets, not acceleration.
     
  4. Dec 30, 2015 #4

    watermelonman

    watermelonman

    watermelonman

    Well-Known Member

    Joined:
    Sep 22, 2014
    Messages:
    2,559
    Likes Received:
    0
    Right, the speed is a going to be a good deal lower but the acceleration number jumped out at me. I mean, I do not think I have seen anything else claim to be in the 3000s of ft/s/s before, and even the 2000s I see are on the lower end of that range. I half imagine the motor taking the mount straight through the epoxy and body upon ignition.
     
  5. Dec 31, 2015 #5

    Sooner Boomer

    Sooner Boomer

    Sooner Boomer

    Well-Known Member

    Joined:
    Mar 21, 2011
    Messages:
    2,436
    Likes Received:
    84
    The I800 is a real kick in the pants. Thrustcurve says the motor puts out 180 lbs (800N) of thrust for a half-second. I think the acceleration/jerk is going to severely stress just about any airframe this side of a greyhound bus.
     
  6. Dec 31, 2015 #6

    mpitfield

    mpitfield

    mpitfield

    Lifetime Supporter Staff Member TRF Lifetime Supporter Global Mod

    Joined:
    Jul 7, 2013
    Messages:
    4,444
    Likes Received:
    210
    Gender:
    Male
    Location:
    Toronto, Ontario
    Hmm looks like an interesting motor. I wouldn't rely on the motor eject though.
     
  7. Dec 31, 2015 #7

    COrocket

    COrocket

    COrocket

    Well-Known Member

    Joined:
    Oct 28, 2009
    Messages:
    817
    Likes Received:
    0
    I've never seen any high power rocket fail in this manner. People have launched ordinary blue tube rockets on Aerotech I1299s. As long as the rocket doesn't have any non-traditional construction techniques, you will be just fine.
     
  8. Dec 31, 2015 #8

    bobkrech

    bobkrech

    bobkrech

    Well-Known Member

    Joined:
    Jan 20, 2009
    Messages:
    8,351
    Likes Received:
    13
    With a lightweight 12 oz. MD rocket similar to a shortened LOC Weasel, the CTI I800 can pull a fierce 136G or ~4,000 fpsps, and the AT I1299 can pull an outrageous 225G or about ~6,000 fpsps. Both flights would have a Max-V around 1,900 fps to 2,000 fps with an apogee ~9400' if the rocket holds together. The issue with either is the potential for column buckling, or in plain English, folding the airframe over.

    Check out http://www.bpasa.com/NERRF.htm for NERRF 3 and the X-16 flight, a LOC Weasel on an I-540. It folded over at 1050 mph (~1540 fps) but the rocket was 42" long and column buckling depends somewhat on the L/D ratio.

    Bob
     
  9. Dec 31, 2015 #9

    Viperfixr

    Viperfixr

    Viperfixr

    Born Again Rocketeer TRF Supporter

    Joined:
    Jan 19, 2009
    Messages:
    1,421
    Likes Received:
    43
    Flew my Lil'Dog DD on one at the last Tripoli Vegas Oktoberfest. Sounded like a cannon going off, then the echo--loved it! The 3lb FWFG Lil'Dog took it, no problem at all, as did the Stratologger and the Duracell 9V.
     
  10. Dec 31, 2015 #10

    CzTeacherMan

    CzTeacherMan

    CzTeacherMan

    Well-Known Member

    Joined:
    Aug 8, 2014
    Messages:
    2,789
    Likes Received:
    136
    TRF user "DJS" flew an I800 on a Wildman Interceptor Sport and Midwest Power. 54mm airframe, 38mm hole, small body rocket. Fantastic flight. Headsnap... As in the entire crowd watching got whiplash. Got it back NO problem whatsoever.
    High impulse/Short burn motors aren't as huge a deal as you think. The moment the fuel burns out, the rocket is decelerating. The real punishment of airframes comes with high impulse/long burn motors... As the high impulse burn continues putting force on the rocket, pushing it faster and faster and faster, the stresses on the airframe continue to build. However, there's not a whole lot of motors in the 38mm range that can overstress a properly built fiberglass airframe.
     
  11. Dec 31, 2015 #11

    watermelonman

    watermelonman

    watermelonman

    Well-Known Member

    Joined:
    Sep 22, 2014
    Messages:
    2,559
    Likes Received:
    0
    Yes, if it was fiberglass I would probably let it rip. It was one of my first rockets, though, initially built with cardboard, wood, and Bob Smith 5m epoxy. I have since discovered that I enjoy abusing it, and gave it a single layer of 2oz fiberglass with West 105. It takes I540s and J290s all day, but the I800 makes me think twice about the internal bonds.
     
  12. Dec 31, 2015 #12

    dixontj93060

    dixontj93060

    dixontj93060

    Well-Known Member

    Joined:
    Feb 20, 2009
    Messages:
    12,882
    Likes Received:
    14
    I sheared fins on a PML Ariel with an I800. Poor flutter profile on those kits--definitely must reinforce that one. On yours couldn't say as you don't give any fin/airframe parameters to calculate flutter risk.
     
  13. Dec 31, 2015 #13

    watermelonman

    watermelonman

    watermelonman

    Well-Known Member

    Joined:
    Sep 22, 2014
    Messages:
    2,559
    Likes Received:
    0
    Oh, it started life as a Nuke Pro Max, so the basic triangular fins. Is flutter more of a risk with increasing acceleration or velocity?
     
  14. Dec 31, 2015 #14

    bobkrech

    bobkrech

    bobkrech

    Well-Known Member

    Joined:
    Jan 20, 2009
    Messages:
    8,351
    Likes Received:
    13
  15. Dec 31, 2015 #15

    T34zac

    T34zac

    T34zac

    Well-Known Member

    Joined:
    Jul 23, 2014
    Messages:
    836
    Likes Received:
    0
    Gender:
    Male
    Location:
    Massachusetts
    I the I800. There's cool motors, and there's REALLY cool motors. I've flown this motor four times. Three times in the rocket I got my L2 with, and once in a minimum diameter (and with what I know now, I'll be the first to admit) that was improperly built. It reached Mach 1 and 100Gs before falling apart, everything that was worth anything (motor casing, tracker, altimeter) came back without damage. Easily one of the most spectacular 'flights' I've ever seen.

    My new 38mm minimum diameter sims to about 10,500' and 160Gs. I'm not sure I'm going to attempt that flight anytime soon.

    But I'd love to put this into my Darkstar Jr. Definitely would be a fun flight to watch. Probably get some good whistle out of it too.
     
    Last edited: Jan 3, 2016
  16. Jan 1, 2016 #16

    g zilla

    g zilla

    g zilla

    Well-Known Member

    Joined:
    Oct 20, 2013
    Messages:
    495
    Likes Received:
    0
    I ve flown 3-4 flights on this motor. 1 was a night flight 4" rocket with 3200 + leds. The other 2 or 3 flights on 54mm fiberglass rocket. It hauls azz.
     
  17. Jan 1, 2016 #17

    3stoogesrocketry

    3stoogesrocketry

    3stoogesrocketry

    Well-Known Member

    Joined:
    Feb 26, 2012
    Messages:
    1,127
    Likes Received:
    61
    So after re reading your first post , why are you concerned about the I 800 if you have flown a K2045 in the airframe before ?

    Eric
     
  18. Jan 1, 2016 #18

    markkoelsch

    markkoelsch

    markkoelsch

    Well-Known Member

    Joined:
    Mar 18, 2009
    Messages:
    4,300
    Likes Received:
    144
    He has not- it was a different rocket.
     
  19. Jan 1, 2016 #19

    djs

    djs

    djs

    Well-Known Member

    Joined:
    Jul 27, 2014
    Messages:
    3,132
    Likes Received:
    168
    Well technically it was 2.25 miles away, and after following my tracker thru 3 farm fields and falling into a ditch, I did find it with no airframe damage, other than a loose rail button. I'll definitely fly that again at MWP14 :)
     
  20. Jan 2, 2016 #20

    CzTeacherMan

    CzTeacherMan

    CzTeacherMan

    Well-Known Member

    Joined:
    Aug 8, 2014
    Messages:
    2,789
    Likes Received:
    136
    This time with a Chute Release...
     
  21. Jan 3, 2016 #21

    watermelonman

    watermelonman

    watermelonman

    Well-Known Member

    Joined:
    Sep 22, 2014
    Messages:
    2,559
    Likes Received:
    0
    Mark is correct. Sorry if that made the topic unclear, all I was trying to say was that I am fairly familiar with vmax motors. In fact I flew another K2045 again yesterday!
    [video=vimeo;150595672]https://vimeo.com/150595672[/video]

    That is Vimeo number 150595672 for those whose browsers disagree with the forum.
     

Share This Page