Page 5 of 5 FirstFirst 1 2 3 4 5
Results 121 to 131 of 131
  1. #121
    Join Date
    23rd July 2014
    Location
    Massachusetts
    Posts
    832
    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
    193
    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
    193
    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. 

Name:	IMG_20170429_143447.jpg 
Views:	69 
Size:	80.3 KB 
ID:	318832Click image for larger version. 

Name:	IMG_20170429_152908.jpg 
Views:	69 
Size:	195.3 KB 
ID:	318828Click image for larger version. 

Name:	IMG_20170429_143133.jpg 
Views:	63 
Size:	80.8 KB 
ID:	318833

    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. 

Name:	IMG_20170429_152133.jpg 
Views:	80 
Size:	206.5 KB 
ID:	318831

    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. 

Name:	IMG_20170429_152207.jpg 
Views:	76 
Size:	192.5 KB 
ID:	318830

    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. 

Name:	IMG_20170429_152835.jpg 
Views:	76 
Size:	178.7 KB 
ID:	318829

    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
    832
    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
    193
    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
    832

    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
    193
    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
    193
    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
    832
    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
    193
    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
    193
    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!



Similar Threads

  1. Mad Cow Frenzy XL 3.0" Build Thread
    By tHoagland in forum High Power Rocketry (HPR)
    Replies: 18
    Last Post: 9th January 2017, 02:55 PM
  2. 4" Madcow Tomach Build Thread
    By Ccolvin968 in forum High Power Rocketry (HPR)
    Replies: 32
    Last Post: 7th January 2017, 12:29 AM
  3. MADCOW 4" FRENZY CARDBOARD ROCKET... A BUILD THREAD #1
    By TMJ in forum High Power Rocketry (HPR)
    Replies: 357
    Last Post: 13th September 2016, 12:48 AM
  4. Madcow Frenzy Build
    By McBoingboing in forum High Power Rocketry (HPR)
    Replies: 4
    Last Post: 27th January 2016, 04:45 PM
  5. Madcow Tomach Build Thread - "Not an Engineer"
    By AlnessW in forum High Power Rocketry (HPR)
    Replies: 98
    Last Post: 6th October 2015, 03:46 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •