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  1. #121
    Join Date
    23rd July 2014
    Location
    Massachusetts
    Posts
    836
    That's an oddly high amount of force that you predict being required to get your drogue out. I don't use shear pins for my drogue compartment, and I use a 2.0g charge for the my main apogee charge and 2.5g for my backup. Same with my main parachute using 3x 2-56 nylon shear pins from McMaster Carr

    NAR# 98194
    Level 1: CTI I-216, 3,043'
    Level 2: CTI K-740, 5,999'

    Personal altitude record: 12,400' CTI L395
    2014 total impulse: 9,018.2 Ns (76% M)
    2015 total impulse: 7,171.7 Ns (40% M)
    2016 total impulse: 18,664.2 Ns (91% N)
    2017 total impulse: 8,281.1 Ns (80% M)

  2. #122
    Join Date
    31st August 2016
    Posts
    210
    Quote Originally Posted by T34zac View Post
    That's an oddly high amount of force that you predict being required to get your drogue out. I don't use shear pins for my drogue compartment, and I use a 2.0g charge for the my main apogee charge and 2.5g for my backup. Same with my main parachute using 3x 2-56 nylon shear pins from McMaster Carr
    It's just based on how much force it took to break the shear pins when I tested it myself... 2x 2-56 took 65lbs one time I tried it, so probably want 80-100lbs of force from the BP to be safe. The main should probably have 150lbs+ to be safe. I'm using 2g for both primary and secondary on the mean. Currently planning on 1.5g primary 2g backup for apogee (1.5g worked great when I was friction fitting) but I need to ground test again with the 2x shear pins.


  3. #123
    Join Date
    31st August 2016
    Posts
    210
    Looks like I'll be flying the maiden flight this coming weekend on a J600! It won't be painted in time, but that's OK since I'll be ground testing before flight anyway and it'd be a shame to mess the paint. I may fly a second time on a K2000. The big goals this weekend are (1) shake down (2) get a better sense of the drag situation and see if it's possible I can fly this under 10k on an M. The camera shrouds are nice and draggy and I won't sand too well :-) I can get openrocket to sim around 9k, and I canalso get it to sim to 11.5k depending on settings.

    Let's talk AV bay. I have two eggtimer quantums with two batteries each, so I'm using two DPDT switches, one for each altimeter. The switches are mounted to the inside wall of the switch band with holes cut to make the toggle accessible. To make the avbay fully removable, I'm using powerpole connectors to connect the switches to the main board. Here are the switches with wires soldered on and connectors crimped.
    Click image for larger version. 

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    Here's a diagram showing my wiring for each altimeter. It isn't all that interesting:


    I designed a laser cut wood assembly to hold the quantums, connector jacks and batteries. This is the top. As you can see, one bulkhead is semi-permanently attached (wires are soldered on), while the other is removable using more powerpole connectors. The two sets of jacks in the bottom are where the switches plug in.
    Click image for larger version. 

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    This is the bottom of the board. You can see the 4 wells for batteries and the JST connectors run to each well.
    Click image for larger version. 

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    This is what it looks like with the batteries put in. A thin piece of plywood slides in over them, locking them in the wells. I use a pin then (middle right side) to keep the plywood in place.

    Click image for larger version. 

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    I'm pretty pleased overall. Everything is very very secure. It's certainly on the heavy side, but I'm not concerned at all about that for this rocket and it was fun to design and build.

  4. #124
    Join Date
    23rd July 2014
    Location
    Massachusetts
    Posts
    836
    Av-bay looks nice. Also looks hefty. Should aid in trying to keep large motors low.

    I think I'll try and make the trip up next weekend. I've got a K740 that I can't keep below 10k unless it's in my Frenzy. But if I can get my hands on an L910 I'll fly that instead.
    NAR# 98194
    Level 1: CTI I-216, 3,043'
    Level 2: CTI K-740, 5,999'

    Personal altitude record: 12,400' CTI L395
    2014 total impulse: 9,018.2 Ns (76% M)
    2015 total impulse: 7,171.7 Ns (40% M)
    2016 total impulse: 18,664.2 Ns (91% N)
    2017 total impulse: 8,281.1 Ns (80% M)

  5. #125
    Join Date
    31st August 2016
    Posts
    210
    Quote Originally Posted by T34zac View Post
    Av-bay looks nice. Also looks hefty. Should aid in trying to keep large motors low.

    I think I'll try and make the trip up next weekend. I've got a K740 that I can't keep below 10k unless it's in my Frenzy. But if I can get my hands on an L910 I'll fly that instead.
    It is hefty indeed :-) Though the rocket seems to be at a weight where a pound up or down doesn't have a big effect.

    No joke, I'm seriously considering mixing a small amount of glitter into my future+simplegreen clearcoat when I paint the rocket (not before this weekend). Should aid with visibility and definitely add some drag :-) I won't use a lot, but I was inspired after seeing a sculpture a month ago that had been finished with a small amount of glitter mixed in to the final coat and it looked pretty cool.

    Let me know if you'll be able to come this weekend, it'd be great to meet and person and I'd love to see your Frenzy.

  6. #126
    Join Date
    23rd July 2014
    Location
    Massachusetts
    Posts
    836

    Madcow FG 4" Frenzy XL build thread

    The glitter would probably aid in visibility quite a bit. That being said, in early April I had visibility on it all the way up and down from 12,400'. Granted at altitude all I could see was the smoke trail and then the drogue chute. But visual tracking was nice to have.

    But yes I'm trying to see if my weekend is open and if it is I'll be on my way up to Maine. The drive is only about an hour and a half for me. Will be worth it even if I only get one motor off.
    NAR# 98194
    Level 1: CTI I-216, 3,043'
    Level 2: CTI K-740, 5,999'

    Personal altitude record: 12,400' CTI L395
    2014 total impulse: 9,018.2 Ns (76% M)
    2015 total impulse: 7,171.7 Ns (40% M)
    2016 total impulse: 18,664.2 Ns (91% N)
    2017 total impulse: 8,281.1 Ns (80% M)

  7. #127
    Join Date
    31st August 2016
    Posts
    210
    Quote Originally Posted by T34zac View Post
    The glitter would probably aid in visibility quite a bit. That being said, in early April I had visibility on it all the way up and down from 12,400'. Granted at altitude all I could see was the smoke trail and then the drogue chute. But visual tracking was nice to have.
    Wow would've loved to see that flight. How much does your Frenzy weigh fully loaded except for the motor case/reload? L395 looks pretty slow off the rod with my build though it'd be tempting! And where did you go to fly it to 12400? It looks like the L395 would take it nearly as high as an M1101.

  8. #128
    Join Date
    31st August 2016
    Posts
    210
    Looks like the launch this weekend may be canceled :-( so I won't be able to fly until June 3 most likely.

    I'm looking at motors. The first flight will be on a J600 that I've already bought to 2k or so feet. I'm eyeing the K2045 for the second flight to 3.5k or so to serve as kind of a stress test (acceleration and deceleration) before sending it up really high. I don't own 75mm hardware yet, and I was going to put that off until I'm ready to do the cert flight in case the rocket gets lost before then. I'm also considering just doing DMS for the cert.

  9. #129
    Join Date
    23rd July 2014
    Location
    Massachusetts
    Posts
    836
    Ive got a k2045. Still trying to figure out what I want it to go in. But I flew my frenzy in Maryland at LDRS this past April for that flight. The L395 is indeed very slow. Fully loaded it was 31 pounds. The RSO was very reluctant to let it go but MDRA staff (who had seen my fly the same motor in the same rocket the previous year) let it go.
    NAR# 98194
    Level 1: CTI I-216, 3,043'
    Level 2: CTI K-740, 5,999'

    Personal altitude record: 12,400' CTI L395
    2014 total impulse: 9,018.2 Ns (76% M)
    2015 total impulse: 7,171.7 Ns (40% M)
    2016 total impulse: 18,664.2 Ns (91% N)
    2017 total impulse: 8,281.1 Ns (80% M)

  10. #130
    Join Date
    31st August 2016
    Posts
    210
    Quote Originally Posted by T34zac View Post
    Ive got a k2045. Still trying to figure out what I want it to go in. But I flew my frenzy in Maryland at LDRS this past April for that flight. The L395 is indeed very slow. Fully loaded it was 31 pounds. The RSO was very reluctant to let it go but MDRA staff (who had seen my fly the same motor in the same rocket the previous year) let it go.
    Woah 31lbs? Isn't the l395 load plus case around 12.5lbs? So your frenzy without motor is 18-19lbs? Btw I think I found your flight on youtube when searching for l395, looked awesome :-)

  11. #131
    Join Date
    31st August 2016
    Posts
    210
    Ground tested again now that I'm using 2x 2-56 pins for the drogue separation. 1.5g (which is what I used when I was planning to friction fit) was enough to shear the pins but the rocket didn't separate as much as I'd have liked, so I'm going with 2g as shown in the video below. I'm also using 2g for my main charges so on the plus side I don't need to worry about messing up on launch day and mixing up where each size charge goes - they are all the same size now!


  12. #132
    Join Date
    31st August 2016
    Posts
    210
    Flew the maiden flight on a CTI J600 to 1651 feet. Everything worked perfectly, including the pair of video cameras I mounted to opposite sides of the rocket. I'm going to try and turn that into a 3d video, but for now here is a composite video of those two cameras and the ground camera synced up:



    The video is pretty high resolution because of the combined cameras, so feel free to go to full screen and enjoy!

    It looks the rocket falls around 60-65fps under the 15" drogue, and (as expected) around 18fps under main.

    I've also purchased my 75mm hardware, hoping to try for my L3 late this fall down at MDRA. Between now and then I'd like to fly on one of the K2000ish Vmaxes to try and test it out under a harsher flight without risking losing it, and maybe another K or two.

  13. #133
    Join Date
    13th February 2016
    Location
    Gilroy, CA
    Posts
    480
    Congrats on your maiden flight! I was impressed with the lack of rotation. Your fins must be lined up well with the body tube. (I'm slowly working to correct my fin slots)
    Do you have and pictures of your camera mounts?
    Kevin NAR, Section #534 LUNAR / TRA
    L2- Madcow Level-2 4" Fiberglass, Redundant DD
    Work in-progress: Madcow 4-inch Fiberglass Frenzy XL

  14. #134
    Join Date
    31st August 2016
    Posts
    210
    Quote Originally Posted by kevinkal View Post
    Congrats on your maiden flight! I was impressed with the lack of rotation. Your fins must be lined up well with the body tube. (I'm slowly working to correct my fin slots)
    Do you have and pictures of your camera mounts?
    Thanks! Yeah the two things I was happiest with about the video were:
    1) Very very little rotation during the boost (the lens distortion makes it hard to tell exactly, but I'm guessing 30 degrees total from liftoff to apogee)
    2) My paint job is shiny enough to see all sorts of awesome reflections off the body and fins :-)

    Regarding rotation, I was pretty sure that my fin slots weren't all that perfect (pretty certain they were worse than yours based on the measurements you gave in your thread), but unlike you I didn't try and correct them since I didn't trust I had the tools/skill to do a better job. I also thought the bevels weren't perfect either, and I had to sand the fins some to make them all the same size. I used a jig to mount them as perpendicular to the rocket and self-aligned as possible, but the slots are the biggest determinant of rotation. As such, I was pretty shocked at how little rotation there was, though to be fair this was a pretty low-key flight. I'm pretty sure there will be a lot more than 30 degrees total rotation when I let her rip :-)

    I don't have a closeup of the camera mounts and I'm traveling so I can't take any pictures until next weekend. However, here's a full-length shot of the rocket, and you can one of the two gray camera shrouds about 3 feet up:
    Click image for larger version. 

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    The cameras are 808 type keychain cameras with a #16 lens. I have one mounted in-line with a fin and the other between the other two fins. This seemed to be the least likely placement to cause any effects on the rocket flight. I used these shrouds from additive aerospace, and attached them with 4-40 screws into standard 4-40 nuts that I epoxied to inside of the airframe. The shrouds work great, with the only annoying thing for my purposes being that the 808 camera has an offset lens, so I'm going to need to do some funny cropping to line the videos up to try and make a 3d video (you can see in the video above that the rocket body isn't perfectly lined up between the two cameras).

    All in all though, I couldn't have had a much better first flight! Though the shrouds aren't draggy enough to keep me under 10k on an M, so I won't be doing that in Maine....

  15. #135
    Join Date
    13th February 2016
    Location
    Gilroy, CA
    Posts
    480
    I think the long boards you clamped to your fins with the bevel cut edges that sat on the booster tube helped with fin alignment. The slots that Madcow put in my booster tube were a sloppy fit to the fins, and then after sanding the fins, there will be even more slop in the fin slot. I think your jig then forced the fins to align with the body nicely, using any available slop in the slot-2-fin joint.

    Regarding your camera mounts, I am familiar with those same units.. in fact I have both the 808 and Mobius versions for 4" airframes. Would you believe that I simply drilled and tapped my 4" FG booster tube for 3mm metric and used four 3mm nylon screws threaded into the thin body tube to secure the camera? After tightening the screws, I simply used a razor to cut them off flush on the inside of the body tube. It's worked perfectly for over 10 flights up to 1000 ft/sec so far... and even survived being dragged through a bumpy plowed hard dirt farm field for about 15 minutes without breaking. If I wanted to spend more money, and I don't, I would put one of the new camera enclosures and shrouds that Madcow is carrying... I forget the name of the manufacturer, but they are nice with a carbon fiber fairing that covers just the camera lens which has been removed from the camera body to minimize how much the camera protrudes into the airflow.

    That really was a nice first flight. I just ran a quick sim on my OpenRocket FG Frenzy 4" XL and the CTI J600RL sims to 2,500 ft! I don't have the camera shrouds modeled, but they can't explain the difference between 1,600 and 2,500 ft. The model shows 249 oz with this motor. I did not add any adapter mass to convert from 75mm motor mount to the 38mm case either. What does your simulation predict for the J600? That's a 998 N-sec impulse, correct?

    I'm glad you posted this.. I will motivate me to work on my rocket and stop fixing things around the house!
    Kevin NAR, Section #534 LUNAR / TRA
    L2- Madcow Level-2 4" Fiberglass, Redundant DD
    Work in-progress: Madcow 4-inch Fiberglass Frenzy XL

  16. #136
    Join Date
    31st August 2016
    Posts
    210
    Quote Originally Posted by kevinkal View Post
    I think the long boards you clamped to your fins with the bevel cut edges that sat on the booster tube helped with fin alignment. The slots that Madcow put in my booster tube were a sloppy fit to the fins, and then after sanding the fins, there will be even more slop in the fin slot. I think your jig then forced the fins to align with the body nicely, using any available slop in the slot-2-fin joint.

    Regarding your camera mounts, I am familiar with those same units.. in fact I have both the 808 and Mobius versions for 4" airframes. Would you believe that I simply drilled and tapped my 4" FG booster tube for 3mm metric and used four 3mm nylon screws threaded into the thin body tube to secure the camera? After tightening the screws, I simply used a razor to cut them off flush on the inside of the body tube. It's worked perfectly for over 10 flights up to 1000 ft/sec so far... and even survived being dragged through a bumpy plowed hard dirt farm field for about 15 minutes without breaking. If I wanted to spend more money, and I don't, I would put one of the new camera enclosures and shrouds that Madcow is carrying... I forget the name of the manufacturer, but they are nice with a carbon fiber fairing that covers just the camera lens which has been removed from the camera body to minimize how much the camera protrudes into the airflow.

    That really was a nice first flight. I just ran a quick sim on my OpenRocket FG Frenzy 4" XL and the CTI 600RL sims to 2,500 ft! I don't have the camera shrouds modeled, but they can't explain the difference between 1,600 and 2,500 ft. The model shows 249 oz with this motor. I did not add any adapter mass to convert from 75mm motor mount to the 38mm case either. What does your simulation predict for the J600? That's a 998 N-sec impulse, correct?

    I'm glad you posted this.. I will motivate me to work on my rocket and stop fixing things around the house!
    My rocket ended up heavy - 16lbs or so with no motor (though including all batteries, cameras, tracker, etc), and then another 0.5lbs for a pair of aeropack adapters to get me from 75mm to 38mm. That left it at 18.5lbs on the pad for the J600 which yeah is about 1kNsec.

    My openrocket file for this is at home (I'm traveling) so I can't check the specifics, but I did add the camera shrouds to the model as a pair of thick fins with dimensions chosen to match the shrouds. I think I may have left them and the main fins as "rounded", and left the finish as smooth paint, and the sim was just about the same as the actual flight after you account for taking off 8 degrees from vertical in fairly substantial winds (12mph at surface if I remember correctly)

  17. #137
    Join Date
    17th January 2011
    Location
    Spring Green WI
    Posts
    2,560
    Are you sure you want to fly a 16.5 lb rocket on the I600?
    TRA 2225
    TWA
    QCRS
    WOOSH

  18. #138
    Join Date
    31st August 2016
    Posts
    210
    Quote Originally Posted by crossfire View Post
    Are you sure you want to fly a 16.5 lb rocket on the I600?
    Who said anything about I600? I flew it on a J600 which was about as small as I'd want to go (went to 1650 feet). From this point forward it'll be Ks and up.

  19. #139
    Join Date
    17th January 2011
    Location
    Spring Green WI
    Posts
    2,560
    Very sorry. I read it wrong.
    TRA 2225
    TWA
    QCRS
    WOOSH

  20. #140
    Join Date
    23rd July 2014
    Location
    Massachusetts
    Posts
    836
    Very nice on it's first flight. Wish I was there to see. I'm going to re build the av-bay on mine before I fly it again. Got a lot of things I want to correct from the first one I did on it.
    NAR# 98194
    Level 1: CTI I-216, 3,043'
    Level 2: CTI K-740, 5,999'

    Personal altitude record: 12,400' CTI L395
    2014 total impulse: 9,018.2 Ns (76% M)
    2015 total impulse: 7,171.7 Ns (40% M)
    2016 total impulse: 18,664.2 Ns (91% N)
    2017 total impulse: 8,281.1 Ns (80% M)

  21. #141
    Join Date
    31st August 2016
    Posts
    210
    Quote Originally Posted by T34zac View Post
    Very nice on it's first flight. Wish I was there to see. I'm going to re build the av-bay on mine before I fly it again. Got a lot of things I want to correct from the first one I did on it.
    Thanks! The next MMMSC launch I might be at is July 15. I'd like to fly on the 75mm K2000 next, but that's contingent on them getting back in stock and the wind playing nice :-) Barring that, perhaps a 54mm K445

    I'd be curious to hear about what you are changing about your av bay - going to be on a build thread?

  22. #142
    Join Date
    23rd July 2014
    Location
    Massachusetts
    Posts
    836
    Not going to be on a build thread. But I've been using key switches to arm/disarm my electronics. While they look cool and are pretty robust, but since they are mounted to the vent band, it requires me to use some pretty lengthy wires so I can actually take the av-bay lids off, so I'm going to replace them with screw switches mounted to the sled. Also I need to accommodate for my MissileWorks RTx unit. Going to add charge cups, replace the terminal blocks, and tidy up the wiring.

    NAR# 98194
    Level 1: CTI I-216, 3,043'
    Level 2: CTI K-740, 5,999'

    Personal altitude record: 12,400' CTI L395
    2014 total impulse: 9,018.2 Ns (76% M)
    2015 total impulse: 7,171.7 Ns (40% M)
    2016 total impulse: 18,664.2 Ns (91% N)
    2017 total impulse: 8,281.1 Ns (80% M)

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