Variable Drag Project

Discussion in 'High Power Rocketry (HPR)' started by Rocketjunkie, Jan 14, 2020.

Help Support The Rocketry Forum by donating:

  1. Feb 22, 2020 #31

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    I have 3 1/8" holes. If I cover 2 holes and suck on the other one, I consistently get good readings, but out on the field if I do exactly the same thing none of them work. (I have 4.) The Fireflys flash the same sequence as the Strattologger beeps so I have no difficulty interpreting the flashes :)
    I intend to give the Estes ones "free to good homes" like kittens :):D for kids.
     
  2. Feb 22, 2020 #32

    BEC

    BEC

    BEC

    Well-Known Member

    Joined:
    Feb 19, 2009
    Messages:
    2,902
    Likes Received:
    140
    Gender:
    Male
    Location:
    Auburn, WA
    The strange thing is that when I set out to intentionally make one fail, I couldn't do it. Even with a nearly sealed small payload compartment, it read a plausible value, and when flown with a FireFly alongside, reported VERY similar results. Truly mysterious.
     
    Last edited: Feb 22, 2020
  3. Feb 22, 2020 #33

    BEC

    BEC

    BEC

    Well-Known Member

    Joined:
    Feb 19, 2009
    Messages:
    2,902
    Likes Received:
    140
    Gender:
    Male
    Location:
    Auburn, WA
    That doesn't make any sense. What else is different between the two situations besides, I'd guess, the temperature? There must be something.
     
  4. Feb 22, 2020 #34

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    Temperature and there is some wind on the field, none in the motel room. I did try waiting various amounts of time between turning the altimeter on and potting it into the payload section.
     
  5. Feb 22, 2020 #35

    BEC

    BEC

    BEC

    Well-Known Member

    Joined:
    Feb 19, 2009
    Messages:
    2,902
    Likes Received:
    140
    Gender:
    Male
    Location:
    Auburn, WA
    The Estes Altimeter has no “installation delay”. It starts looking for the pressure change (amount unknown) and, I think, rate of pressure change (again, amount unknown) to trigger it’s “I’m flying” logic. So waiting times should not matter. It’s hard for me to imagine that winds blowing into/across static ports would fool it into not thinking it is flying.

    Note, by the way, that the apogee is NOT locked in and pulling the nose cone off the payload section with the static ports blocked will change the result it reports.

    All this is really more argument to use the FireFly. Lighter, less expensive and much more consistently reliable. And if you can manage to catch the Firefly Field Data Display in stock on perfectflitedirect.com then you can just plug it in and read altitude, max speed, flight time, and descent rate from the display.
     
  6. Feb 22, 2020 #36

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    The Estes altimeters never show a liftoff detect. They still read 0 on recovery. I'm moving to the 4", it will recover dual deploy with the Strattologger CF and so doesn't need a second altimeter.
     
  7. Feb 28, 2020 #37

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    Received the box of LOC parts today. Will be referred to as TV400. Enough parts for 2 boosters, 4 payload bays, and 1 set of 6 plates.
    TV400 build 01a.jpg TV400 build 02a.jpg
    This is the first time in over 30 years I've gotten LOC nose cones that weren't white:) The white one is the nose cone from my original (1989) EZI, the only part of the rocket I still have. Also parts to repair You Gotta Be Nuts! that was damaged by a J99 cato.
     
  8. Feb 28, 2020 #38

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    The plates on this one will be slightly smaller than the direct scale of the TV60, 7" instead of 7.31" giving a triangle size of 10.39". Tube fins will be 1/6 of a 34" tube (5-5/8"), main body will be 1 34" tube, and main chute bay will be 1/2 of a 34" tube.
    I also mixed up 4 2 grain 54mm J220s (700 N-s). Planning a set of flights at the April ICBM launch.
     
  9. Feb 29, 2020 #39

    BABAR

    BABAR

    BABAR

    Builds Rockets for NASA TRF Lifetime Supporter TRF Supporter

    Joined:
    Aug 27, 2011
    Messages:
    5,182
    Likes Received:
    812
    Does airflow over the vent holes distort the measured altitude?
     
  10. Feb 29, 2020 #40

    Nytrunner

    Nytrunner

    Nytrunner

    Master of Rivets

    Joined:
    Oct 15, 2016
    Messages:
    5,951
    Likes Received:
    1,537
    Gender:
    Male
    Location:
    Huntsville AL
    Older altimeters could be spooked by turbulence at mach. Then youd have to set a mach delay period so it wouldnt deploy before then.

    These days the altimeter is pretty good about ignoring the fluctuations through boost/coast and reading the final altitude in "still" air.
     
  11. Mar 1, 2020 #41

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    Start construction with avbays. Started with 1/2" OD, .120 wall aluminum tubing. ID of .260" is just right for 5/16" UNC threads, so cut to 5-5/8" long and tap both ends. Enlarge center hole of bulkheads to 5/16".
    TV400 build 03a.jpg
    Picture shows all 4 rods with 5/16" eye bolts along with centering ringsand bulkheads.
    Next picture shows dry fit of altimeter bay, then with altimeter. All my rockets have this style altimeter bay so I can use any altimeter in any rocket.
    TV400 build 04a.jpg TV400 build 05a.jpg TV400 build 06a.jpg
    Altimeter bay fitted in coupler, rear, inside, and front.
    TV400 build 07a.jpg TV400 build 08a.jpg TV400 build 09a.jpg
     
  12. Mar 1, 2020 #42

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    Couplers cut for the other 3 bays
    TV400 build 10a.jpg
    Epoxy the bulkheads and threads on the forward end of the center rod.
    TV400 build 12a.jpg TV400 build 13a.jpg TV400 build 14a.jpg
    Repeat 3 more times for the other 3 bays.
    TV400 build 15a.jpg
     

    Attached Files:

    Lukun7 likes this.
  13. Mar 5, 2020 #43

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    Add 50" chutes, main recovery harness, and nose cones to payload bays.
    TV400 build 16a.jpg TV400 build 17a.jpg TV400 build 18a.jpg
    17 and 18 shows how I add eye bolt to nose cone. Forged are not necessary here as they only need to withstand the weight of the nose cone.
    Begin work on thrust plates and booster bodies.
    Thrust plates with template I used to mark the plywood. The line from the round portion to directly out is 7".
    TV400 build 20a.jpg
    Thrust plates with 4" long couplers
    TV400 build 19a.jpg
    Stop and prep other rockets for this weekend's ROSCO launch near Camden, SC
    Other rockets prepped.jpg
    High Tech H45 on CTI H54, Motoreater on J460 and 2 H97, Deuce on 2 J150, and 3" Tuber on I59.
     
  14. Mar 5, 2020 #44

    Buckeye

    Buckeye

    Buckeye

    Well-Known Member

    Joined:
    Sep 6, 2009
    Messages:
    2,283
    Likes Received:
    212
    Why are 4 rockets needed? Can you make the modular drag plates removeable/configurable on just one rocket?
     
  15. Mar 5, 2020 #45

    GlenP

    GlenP

    GlenP

    Well-Known Member

    Joined:
    Oct 4, 2014
    Messages:
    1,674
    Likes Received:
    159
    Why, so you can have a DRAG RACE, of course!
     
  16. Mar 5, 2020 #46

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    For the 4", I'm building 2 rockets. I prefer to preprep the rockets at home so that's why I have 4 payload sections. There was not much difference in cost between 1 booster section and 2 so I went ahead and got enough parts for 2 boosters. The drag plates are removable and can be moved from 1 rocket to another. The 7.5" version will be only 1 rocket.
     
  17. Mar 8, 2020 #47

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    The Camden launch scheduled for this weekend was cancelled :(. Standing water on the field, Looks like Sunday would have been perfect, sunny, high low 60s, and light wind never going above 4 mph.
    So, back to work on the TV400s.
    Cut tube fins and seal the edges with CA
    TV400 build 22a.jpg
    Align with bulkhead, coupler, and tube fin then wood glue the bulkhead to drag plate. Wood glue the coupler next. Once the wood glue dries, use epoxy to fillet the bulkhead-coupler joint.
    TV400 build 23a.jpg TV400 build 25a.jpg TV400 build 26a.jpg TV400 build 30a.jpg
    Repeat for the other 5 drag plate assemblies They're on the TV60s flown on D and E motors.
    TV400 build 29a.jpg
     
  18. Mar 8, 2020 #48

    beeblebrox

    beeblebrox

    beeblebrox

    8 C6-0, 12 D11-9, 20 D20-0, 20 E5-0, 3 Cinerocs

    Joined:
    Mar 19, 2016
    Messages:
    422
    Likes Received:
    109
    Gender:
    Male
    Location:
    West Chester, PA
    Where is the Camden you reference? If you mean Camden NJ, give me club contact info for future reference!
     
  19. Mar 8, 2020 #49

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    Camden, SC. About 1/2 hour east of Columbia. Home of ICBM and ROSCO clubs. Info in the group rocketrysouthcarolina on Facebook, some info at rocketrysouthcarolina.org
     
  20. Mar 11, 2020 #50

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    Continuing the build.
    54 mm motor mounts, 12" long TV400 build 32a.jpg
    Attach tube fins to booster section. TV400 build 33a.jpg
    Then install motor mount TV400 build 34a.jpg
    I did install the nuts that came with the CRs but they will need longer screws to clear the motor tube. I just tape in the motor.
    Shock cord mount, a length of shock cord and a blob of epoxy. This is like the old style LOC string mount but far less likely to zipper. TV400 build 36a.jpg
    Apogee harnesses. About 40ft. long. The regular quick link fits on the booster shock cord mount, the longer one is needed to fit over the 5/16" eye bolt on the altimeter bay. TV400 build 37a.jpg View with booster sections TV400 build 39a.jpg
    Also mixed up 4 2 grain 54 mm white J220s. About 700 N-s. TV400 build 41a.jpg They use the small hole closure and 29 mm nozzle. Lots cheaper than a 54 mm nozzle.
     
  21. Mar 11, 2020 #51

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    Next, I sanded the oversize from the drag plates until they fit.
    TV400-6 TV400 build 43a.jpg
    TV400-4 TV400 build 44a.jpg TV400-2 TV400 build 45a.jpg TV400-0 TV400 build 46a.jpg
    Both boosters,one with all 6 plates, the other with none. TV400 build 42a.jpg
    All that's needed are rail buttons in tube 6 for when not flying all 6 plates. If all 6 are used it will fly off a 1/2" rod between the tube fins. The rail buttons will be surface mounted, 1 inside tube fin and 1 above it. See next post coming within a few days.
     
    Last edited: Mar 11, 2020
  22. Mar 13, 2020 #52

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    (TV400 47, 50) Glue on nuts with rail buttons on them. TV400 build 47a.jpg TV400 build 50a.jpg
    (TV400 52, 53) Bend flanges to fit 1 for outside of BT, the other for inside of fin. TV400 build 52a.jpg TV400 build 53a.jpg
    (TV400 54, 55, 56) Nuts installed on 1 booster. Repeat for the second. TV400 build 54a.jpg TV400 build 56a.jpg
    (TV400 57, 58, 59) Roll launch lug 9/16" ID, 4 layers thick from gummed paper tape. Last picture shows a 1/2" threaded rod in launch rod configuration. TV400 build 57a.jpg TV400 build 58a.jpg TV400 build 59a.jpg
     
  23. Mar 23, 2020 #53

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    Finishing up the TV400 build.
    TV400 build 60a.jpg
    Apply 2 coats of filler primer to drag plates, sanding 220 then 400 grit after each coat.
    TV400 build 61a.jpg TV400 build 62a.jpg
    A single plastic rivet prevents the drag plates from rotating when using less than 6. You can see the other booster with rivet holes in the background.
    This completes construction of these test vehicles.
     
  24. Mar 24, 2020 #54

    Nytrunner

    Nytrunner

    Nytrunner

    Master of Rivets

    Joined:
    Oct 15, 2016
    Messages:
    5,951
    Likes Received:
    1,537
    Gender:
    Male
    Location:
    Huntsville AL
    I missed it apparently, how do you secure the plates to the rocket so they don't get blown out the back?
     
  25. Mar 24, 2020 #55

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    The plates have a 4" section of coupler that fits into the tube fin. See the plate construction in post #47. The loads are asymmetric, so the load tends to jam the coupler. In addition, there is a rivet, that in addition to preventing rotation, also prevents the coupler from slipping out. In the TV60, I just used a small piece of masking tape to make sure the coupler stayed in. These rockets are NOT designed to go any where near supersonic!
     
  26. Mar 25, 2020 #56

    Nytrunner

    Nytrunner

    Nytrunner

    Master of Rivets

    Joined:
    Oct 15, 2016
    Messages:
    5,951
    Likes Received:
    1,537
    Gender:
    Male
    Location:
    Huntsville AL
    Doh, the rivets!

    Hopefully that'll keep things nice and secure, and the scale up of the area won't turn into killer drag on the plates
     
  27. Apr 7, 2020 at 2:27 AM #57

    Rocketjunkie

    Rocketjunkie

    Rocketjunkie

    Addicted to APCP

    Joined:
    Jan 19, 2009
    Messages:
    3,890
    Likes Received:
    181
    4" TV400 rockets ready to fly. Project on hold until HPR launches resume.
     

Share This Page

Group Builder