Help Support RocketryForum by donating using the link above or becoming a Supporting Member.


Page 1 of 2 1 2 LastLast
Results 1 to 30 of 34
  1. #1
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119

    Blue Stage - High Power Two Stage

    I've decided to try building a high power two stage rocket. I've never used Blue Tube but I've heard good things about it, so, I'm planning to use 4" Blue Tube. I'm not sure what the final name will be but so far it is "One Stage, Two Stage, Red Stage, Blue Stage". That is kind of a long name, so, I'm hoping to come up with something shorter.

    I haven't started building yet, but, so far here's my plan:
    4" Blue Tube, approx. 92" total height.
    1/4" plywood fins mounted TTW.
    54mm MMT in the booster and 38mm MMT in the sustainer.
    An Eggtimer Quantum, located in the sustainer, will light the sustainer.
    An Eggtimer Quark, located in the nose cone, will handle deployment for the sustainer. I'm thinking I'll either use a Cable Cutter or a Chute Release on the main chute to reduce the drift on the sustainer.
    If needed, I have a custom-build GPS tracker that I can also mount in the nose cone.
    The booster will drag separate or separate when the sustainer motor fires. I'm going to line inside of the inter-stage coupler with thinned JB Weld to protect it from heat damage.
    The booster parachute will be deployed using the booster motor. Depending on the booster motor, I will use a Chute Release on the booster parachute.

    I've got a design in Open Rocket which I will post later. I think/hope I'm on the right track, but, I'm still researching a few things, like, how much stability should I be aiming for on each stage and what is the best way to build an avionics bay near the MMT in the sustainer. Also, can I cut Blue Tube using my compound mitre/chop saw or should I use a hand saw. Any and all rocket-related advice is greatly appreciated.

    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  2. #2
    Join Date
    15th October 2016
    Location
    Huntsville AL
    Posts
    2,140
    Quote Originally Posted by kswing View Post
    I've decided to try building a high power two stage rocket. I've never used Blue Tube but I've heard good things about it, so, I'm planning to use 4" Blue Tube. I'm not sure what the final name will be but so far it is "One Stage, Two Stage, Red Stage, Blue Stage". That is kind of a long name, so, I'm hoping to come up with something shorter.

    I haven't started building yet, but, so far here's my plan:
    4" Blue Tube, approx. 92" total height.
    1/4" plywood fins mounted TTW.
    54mm MMT in the booster and 38mm MMT in the sustainer.
    An Eggtimer Quantum, located in the sustainer, will light the sustainer.
    An Eggtimer Quark, located in the nose cone, will handle deployment for the sustainer. I'm thinking I'll either use a Cable Cutter or a Chute Release on the main chute to reduce the drift on the sustainer.
    If needed, I have a custom-build GPS tracker that I can also mount in the nose cone.
    The booster will drag separate or separate when the sustainer motor fires. I'm going to line inside of the inter-stage coupler with thinned JB Weld to protect it from heat damage.
    The booster parachute will be deployed using the booster motor. Depending on the booster motor, I will use a Chute Release on the booster parachute.

    I've got a design in Open Rocket which I will post later. I think/hope I'm on the right track, but, I'm still researching a few things, like, how much stability should I be aiming for on each stage and what is the best way to build an avionics bay near the MMT in the sustainer. Also, can I cut Blue Tube using my compound mitre/chop saw or should I use a hand saw. Any and all rocket-related advice is greatly appreciated.
    Sounds awesome! Will read

    Please call it Red-Stage/Blue-Stage. With propellant choices to match!

    "I'm at least 70% confident about whatever I say (90% of the time)"- college me

    NAR 101195
    Level 1: Big SAM, 9/10/16

  3. #3
    Join Date
    30th January 2016
    Location
    US > OK > NE
    Posts
    3,737
    OTR-B good :-D

  4. #4
    Join Date
    22nd August 2015
    Location
    Rhode Island
    Posts
    1,282
    Iím working towards my first HPR 2-stage flight in 2018 too. Iíll be watching this intently.


    Sent from my iPhone using Rocketry Forum
    NAR #100940, RIMRA & CMASS
    L1 - 4/17/16, Tyrannosaur (by Binder Design), Loki H144
    L2 - 8/19/17, Terrordactyl (by Binder Design), CTI J250

  5. #5
    Join Date
    11th January 2012
    Location
    Commonwealth of VA
    Posts
    1,603
    Quote Originally Posted by kswing View Post
    Also, can I cut Blue Tube using my compound mitre/chop saw or should I use a hand saw?
    I have a lot of experience with Blue Tube, and it works well for me. Cutting with a compound mitre saw works great.

    -Bill Riley

    TRA: 12294
    NAR: 89196

    A good rule for rocket experimenters to follow is this: always assume that it will explode.
    ó Astronautics, issue 38, October 1937.


  6. #6
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119
    Quote Originally Posted by Worsaer View Post
    I have a lot of experience with Blue Tube, and it works well for me. Cutting with a compound mitre saw works great.
    Thanks for the advice on cutting Blue Tube.

    Below is an image from Open Rocket. So far I'm looking at stability of about 3.2 when staging from a J to an I and about 2.4 when staging from a K to a J. Upper stage stability is above 2 for both.

    Click image for larger version. 

Name:	otrb.png 
Views:	117 
Size:	1.13 MB 
ID:	334846
    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  7. #7
    Join Date
    15th October 2016
    Location
    Huntsville AL
    Posts
    2,140
    Fantastic

    Looks like it could fly straight out of a dr. Seuss book. just needs oh the Places You'll Go on the side.

  8. #8
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119
    So far I haven't made much progress except for cutting the booster tube and sealing it with sanding sealer. The compound mitre saw worked quite well.

    I'm debating between using standard dual deploy for the sustainer or putting both the deployment altimeter and the tracker in the nose cone and using a cable cutter or a chute release on the main. The advantage I see to dual deploy is that I'm familiar with it and it would make it easier to launch just the booster along with the dual deploy section. The advantage I see with everything in the nose cone is there will be one less deployment charge and parachute to setup and maintain.

    Also, what is the best igniter to use for lighting the sustainer? I'm thinking I may try dipping one of my dual deploy e-matches in pyrogen, but, I'm wondering if there is a better way.
    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  9. #9
    Join Date
    22nd August 2015
    Location
    Rhode Island
    Posts
    1,282
    Quote Originally Posted by kswing View Post
    So far I haven't made much progress except for cutting the booster tube and sealing it with sanding sealer. The compound mitre saw worked quite well.

    I'm debating between using standard dual deploy for the sustainer or putting both the deployment altimeter and the tracker in the nose cone and using a cable cutter or a chute release on the main. The advantage I see to dual deploy is that I'm familiar with it and it would make it easier to launch just the booster along with the dual deploy section. The advantage I see with everything in the nose cone is there will be one less deployment charge and parachute to setup and maintain.

    Also, what is the best igniter to use for lighting the sustainer? I'm thinking I may try dipping one of my dual deploy e-matches in pyrogen, but, I'm wondering if there is a better way.
    Most people say to use CTI motors in the sustainer. They have a pyrodex pellet in them that makes ignition a piece of cake with an e-match. That's what I'm planning to do.
    NAR #100940, RIMRA & CMASS
    L1 - 4/17/16, Tyrannosaur (by Binder Design), Loki H144
    L2 - 8/19/17, Terrordactyl (by Binder Design), CTI J250

  10. #10
    Join Date
    23rd July 2011
    Location
    Butte, MT
    Posts
    2,550

    Blue Stage - High Power Two Stage

    Quote Originally Posted by BDB View Post
    Most people say to use CTI motors in the sustainer. They have a pyrodex pellet in them that makes ignition a piece of cake with an e-match. That's what I'm planning to do.
    Just for correctness, CTI doesnít use a pyrodex pellet. They use a pressed black powder pellet of their own design. Individual rocketeers like us use pyrodex pellets to try and emulate the black powder pellet.
    Last edited by Steve Shannon; 24th December 2017 at 03:53 AM.
    Steve Shannon
    L3CC, TAP, Director, Tripoli Rocketry Association

  11. #11
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119
    Quote Originally Posted by BDB View Post
    Most people say to use CTI motors in the sustainer. They have a pyrodex pellet in them that makes ignition a piece of cake with an e-match. That's what I'm planning to do.
    Thanks for the advice. So far I only have AeroTech hardware.....maybe it's time I start looking at CTI hardware.

    I've also read about coating the top grains of the motor with pyrogen, so, that may be another option I need to look into.
    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  12. #12
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119
    I've been looking at my risk factors and risk mitigation and here's what I have so far:
    Risk: Quantum fails or sustainer doesn't light - Mitigation: Quark still deploys drogue and then main
    Risk: Sustainer lights and Quark fails - Mitigation: Upper stage motor ejection deploys drogue - no ballistic reentry
    Risk: Booster doesn't drag separate - Mitigation: Upper stage ignition will force separation
    Risk: Booster motor ejection fails - Mitigation: None - acceptable risk - low probability and booster should be mostly unstable with large fins and no nosecone

    I'm trying to have one layer of redundancy for most likely events - am I missing any big risks here?

    I may try to configure the second channel on the Quantum to act as a tertiary backup for the main deployment.

    So far I'm planning to use a Blue Tube coupler to join the booster and sustainer and my design has it going about 3" or 3.5" into the bottom of the sustainer. I'm planning to have 3 centering rings in the sustainer and recess the lower centering ring by 3.5" so it won't interfere with the coupler. I'm basing this on the avionics bays I see for sale and they often seem to be 8" long (for a 4" rocket) with a 1" switch band, so, that would be a 3.5" overlap. My question is, will 3" of Blue Tube coupler be enough overlap between the two stages? How often have folks seen rockets fail at a coupler? Please keep in mind that this design probably won't be going supersonic.

    Also, in light of previous comments and other research I've done, I've ordered CTI hardware so that I can use CTI motors in the sustainer to enhance my odds for ignition.
    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  13. #13
    Join Date
    22nd August 2015
    Location
    Rhode Island
    Posts
    1,282
    Quote Originally Posted by kswing View Post
    I've been looking at my risk factors and risk mitigation and here's what I have so far:
    Risk: Quantum fails or sustainer doesn't light - Mitigation: Quark still deploys drogue and then main
    Risk: Sustainer lights and Quark fails - Mitigation: Upper stage motor ejection deploys drogue - no ballistic reentry
    Risk: Booster doesn't drag separate - Mitigation: Upper stage ignition will force separation
    Risk: Booster motor ejection fails - Mitigation: None - acceptable risk - low probability and booster should be mostly unstable with large fins and no nosecone

    I'm trying to have one layer of redundancy for most likely events - am I missing any big risks here?

    I may try to configure the second channel on the Quantum to act as a tertiary backup for the main deployment.

    So far I'm planning to use a Blue Tube coupler to join the booster and sustainer and my design has it going about 3" or 3.5" into the bottom of the sustainer. I'm planning to have 3 centering rings in the sustainer and recess the lower centering ring by 3.5" so it won't interfere with the coupler. I'm basing this on the avionics bays I see for sale and they often seem to be 8" long (for a 4" rocket) with a 1" switch band, so, that would be a 3.5" overlap. My question is, will 3" of Blue Tube coupler be enough overlap between the two stages? How often have folks seen rockets fail at a coupler? Please keep in mind that this design probably won't be going supersonic.

    Also, in light of previous comments and other research I've done, I've ordered CTI hardware so that I can use CTI motors in the sustainer to enhance my odds for ignition.
    I like the risk mitigation scheme. I've tried to light a sustainer with my Quantum twice and had it fail twice. Both times were my fault programming it. I had planned on motor eject for sustainer deployment, so both flights ended in a destroyed sustainer. Luckily, I was just staging an F50 to a C11 with a BT60 rocket, so there wasn't much of a safety hazard in the crashes. But in retrospect, I should have planned for the possible failure. Next time, I'll use my quantum to also fire a deployment charge.
    NAR #100940, RIMRA & CMASS
    L1 - 4/17/16, Tyrannosaur (by Binder Design), Loki H144
    L2 - 8/19/17, Terrordactyl (by Binder Design), CTI J250

  14. #14
    Join Date
    9th October 2013
    Location
    San Jose, CA
    Posts
    690
    I'll start off by saying my experience in 2-stage flights is exactly one flight, but it was a successful flight, so that makes me an expert, right? (PLEASE note the sarcasm here) By the second week in January I hope to be able to say 2-out-of-2, have a J394G3-to-I255RL lined-up for my second flight, was going to fly it earlier this month but the RRC3 in the sustainer threw a fit on the pad with ~20 minutes left on the waiver, so I packed things up at that point. Anyway, my thread for my semi-custom 2-stage Osprey 75 is here.

    Oh, and I think "Red Stage, Blue Stage" is a fantastic name. Me, I'd be shooting for red motors in the booster and blue motors in the sustainer, also.

    Quote Originally Posted by kswing View Post
    An Eggtimer Quantum, located in the sustainer, will light the sustainer.
    An Eggtimer Quark, located in the nose cone, will handle deployment for the sustainer. I'm thinking I'll either use a Cable Cutter or a Chute Release on the main chute to reduce the drift on the sustainer.
    If needed, I have a custom-build GPS tracker that I can also mount in the nose cone.
    The booster will drag separate or separate when the sustainer motor fires. I'm going to line inside of the inter-stage coupler with thinned JB Weld to protect it from heat damage.
    The booster parachute will be deployed using the booster motor. Depending on the booster motor, I will use a Chute Release on the booster parachute.
    So if I got that, the sustainer has a single separation point, so you have electronics in the nose and are basically electronic backup for a motor eject sustainer (or perhaps vice-versa), with a Chute Release (or similar) doing the actual main deployment.

    Quote Originally Posted by kswing View Post
    I've been looking at my risk factors and risk mitigation and here's what I have so far:
    Risk: Quantum fails or sustainer doesn't light - Mitigation: Quark still deploys drogue and then main
    Risk: Sustainer lights and Quark fails - Mitigation: Upper stage motor ejection deploys drogue - no ballistic reentry
    My main concern here is whether motor eject will even be an option in the sustainer. It totally depends on the motor combos you're looking at, but in my research for my 2-stage rocket motor combos I've found that the coast phase for the sustainer is typically longer than the motor is designed for (since the motor assumes its starting from zero, but the sustainer will be going [much?] faster when the sustainer motor lights), so even at the longest (undrilled) delay the sustainer's motor could be firing before apogee. Now perhaps if you're only popping the nose and the chute remains reefed maybe that won't zipper, but it seems risky to me.

    Also, depending on the altitudes (motor selection) and where the Chute Release ends up in the airframe, you might see some of what I know as 'piston effects', where the motor acceleration causes the column of air in the parachute section to shift up/down creating localized areas of higher or lower pressure, so I'd wonder if, depending on your motor choices and the altitude of first-stage burnout and second-stage ignition, if the CR might be fooled into seeing the ejection altitude inside the rocket. Worst thing that typically happens here is the main comes out at apogee, if the rocket isn't going too fast that should be fine it just might be a longer walk. If the motor eject goes off early it could be worse. I flew a CR in my 2-stage but it was in the booster, so it only saw one motor ignition/burnout. Better ventilation in the payload section (holes near the top and bottom) can help reduce/eliminate this.

    Quote Originally Posted by kswing
    Risk: Booster doesn't drag separate - Mitigation: Upper stage ignition will force separation
    I guess a lot of (some?) people do this, I've designed both of my 2-stagers to have an ejection charge in the ISC forward bulkhead. I just didn't like the thought of the motor coming up to pressure while it's still enclosed in the ISC, so if there wasn't a drag separation the motor might over-pressurize? My 3"-to-3" rocket didn't separate until the charge fired, and it was not a tight fit between the ISC and sustainer. My second 2-stage is 4"-to-54mm, so it seems like there will be more drag with the transition, when it was just the large Osprey 75 fins creating the drag that wasn't enough for my rocket to separate. Since you're also same size booster/sustainer I wonder if you'll see any drag separation.

    Quote Originally Posted by kswing
    Risk: Booster motor ejection fails - Mitigation: None - acceptable risk - low probability and booster should be mostly unstable with large fins and no nosecone
    This part scares me personally, but once you've bit the bullet for an ejection charge in the ISC that means electronics in the ISC, so having that electronics handle both separation and apogee deployment for the booster becomes pretty simple. So for me it was a no-brainer since I was going to have the electronics there anyway. I had also decided to have a tracker in both stages, largely because the experienced 2-stage flyer at our launches was always asking for help with keeping an eye on the booster so that he wouldn't lose it, I decided to fly trackers in both parts so that I'd never be wondering where the booster wound up. =)

    Quote Originally Posted by kswing
    I may try to configure the second channel on the Quantum to act as a tertiary backup for the main deployment.
    I think you may find that this option is necessary since the motor delay may not be able to be made long enough, so it may be your only viable backup.

    Quote Originally Posted by kswing
    So far I'm planning to use a Blue Tube coupler to join the booster and sustainer and my design has it going about 3" or 3.5" into the bottom of the sustainer. I'm planning to have 3 centering rings in the sustainer and recess the lower centering ring by 3.5" so it won't interfere with the coupler. I'm basing this on the avionics bays I see for sale and they often seem to be 8" long (for a 4" rocket) with a 1" switch band, so, that would be a 3.5" overlap.
    For the 4" kits I have (Binder Excel w/DD, RW X-celerator) the couplers have been 14" and 9", with 4" and 1" vent bands, respectively. The former is big, you glue 2 7" couplers together at the 4" vent band, and end up with 5" overlap on each end (though I had my vent band lengthened an inch so that an Additive Aerospace Mobius camera shroud would fit on the band, leaving 4.5" on each side), the X-celerator was clearly designed for a 1" vent band and 4" of overlap on each end. I've heard on this forum multiple times the recommendation that the coupler overlap always be at least one caliber, my RW Double Shot was definitely designed so that the ISC would go just over 54mm into the 54mm sustainer, when I designed my 2-stage Osprey 75 I similarly designed for a 3" mate in the 3" sustainer. Now as to whether 3.5" or 3" is 'close enough' to 4" that it works I can't say, I'd imagine it also depends on the flexibility of the tubing (and how tight of a fit between the coupler and tube) and I have absolutely no experience with Blue Tube, both of my 2-stagers are fiberglass. Keep in mind that you have one rocket pushing another through the ISC, so there's a good bit more weight (and a bigger moment arm) resting on this coupler than in your typical avionics bay/nosecone coupler, so if the sustainer wants to tilt during booster firing the ISC is the only thing keeping things straight.
    Will Ferry (Launches & Videos) NAR #96512 (L2) / TRA #15328 (L2) / LUNAR #2759
    L1: 9/2013 @ XPRS, GLR T-Bolt "Thunderbolt" (R.I.P.), H148R
    L2: 4/2016 @ TCC Helm, Binder Design Excel w/DD "dd2.xls", J315R
    Impulse flown (flights): 2013: 767Ns (2), 2014: 4298Ns (8), 2015: 7486Ns (16), 2016: 11693Ns (18), 2017: 11138Ns (16), 2018: 3879Ns (5)

  15. #15
    Join Date
    18th January 2009
    Location
    Savannnah, Ga
    Posts
    7,917
    You have overlooked the most serious risk factors, the arming procedure at the pad. Went right to the middle & the end. you need to include the beginning.
    How am I arming and testing, before going to pad with out risk of sustainer ignition?
    Igniter's not in motor, separate ignition test with another igniter, OUTSIDE of sustainer.
    Testing trackers and base.
    Cold start GPS systems, so I have hot start at pad.
    Get 4-5 D sat position checked for GPS function.
    Transport sections to pads.
    Assembly of booster-sustainer at pads
    When- where RSO'd

    Safest arming sequence of my electronics.
    All personal clear from pad area BEFORE I arm sustainer.
    What do I do if sustainer lights at pad while I'm on ladder arming it.[or any scenario]

    Just a few things ya don't worry about normal single stage flights.
    Now you are personally responsible for pad safety of those around you, in a manner not normally thought of.

    What am I doing to prevent sustainer ignition if rocket has begun gravity turn towards earth, or in bad off vertical position.
    Am I sure there is enough thrust/stack ratio to safely lift the whole thing off rail.
    Is velocity going to be high enough , when time for sustainer ignite, [not too much coast delay]

    Just a few items you may wish to add. Before it leaves the pad.
    Jim Hendricksen
    L-3 Tripoli 9693
    [ICBM, Orangeburg,SC R.I.P.] - QCRS ,Princeton ILL - MDRA , Price Maryland - Woosh, Bong Wisconsin- ROCC, Charlotte NC , ICBM Camden SC
    "Made" member of Chicago & Carolina Rocket Mafia
    Rocketry...........an exact science.......but not exactly !!!

  16. #16
    Join Date
    26th November 2009
    Posts
    5,214
    What about HEI Jim? Do you dry test, that is test everything out at home without propellant grains in the motor case to judge stability of your system and electronics? Then setup and save arming the sustainer for last? Kurt

  17. #17
    Join Date
    22nd August 2015
    Location
    Rhode Island
    Posts
    1,282
    Quote Originally Posted by blackjack2564 View Post
    You have overlooked the most serious risk factors, the arming procedure at the pad. Went right to the middle & the end. you need to include the beginning.
    How am I arming and testing, before going to pad with out risk of sustainer ignition?
    Igniter's not in motor, separate ignition test with another igniter, OUTSIDE of sustainer.
    Testing trackers and base.
    Cold start GPS systems, so I have hot start at pad.
    Get 4-5 D sat position checked for GPS function.
    Transport sections to pads.
    Assembly of booster-sustainer at pads
    When- where RSO'd

    Safest arming sequence of my electronics.
    All personal clear from pad area BEFORE I arm sustainer.
    What do I do if sustainer lights at pad while I'm on ladder arming it.[or any scenario]

    Just a few things ya don't worry about normal single stage flights.
    Now you are personally responsible for pad safety of those around you, in a manner not normally thought of.

    What am I doing to prevent sustainer ignition if rocket has begun gravity turn towards earth, or in bad off vertical position.
    Am I sure there is enough thrust/stack ratio to safely lift the whole thing off rail.
    Is velocity going to be high enough , when time for sustainer ignite, [not too much coast delay]

    Just a few items you may wish to add. Before it leaves the pad.
    Jim is right that the biggest safety issue with a two stage HPR rocket is arming the sustainer. The Quantum should help with that because it can be armed remotely, but you need to be sure to insert the igniter and arm the Quantum only when the rocket is upright on the pad.
    NAR #100940, RIMRA & CMASS
    L1 - 4/17/16, Tyrannosaur (by Binder Design), Loki H144
    L2 - 8/19/17, Terrordactyl (by Binder Design), CTI J250

  18. #18
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119
    Thanks again for all of the feedback. I'm still looking into the best way to couple the booster and sustainer to ensure that they are strong enough yet will still separate when needed. In order to reduce complexity a bit, I've decided to go with standard dual-deploy (using the Eggtimer Quark) for the sustainer since I've done that successfully 10 or 20 times. I'll only have the tracker in the nose cone. This also helps by moving the Quark arming switch down a bit so that I should be able to reach it without a ladder.

    I've put a lot of thought into how to safely arm and launch the rocket and based on the above comments I've put even more thought into it. The Quantum has some safety checks, such as a minimum safe altitude and a minimum safe vertical velocity, that I plan to take advantage of to ensure I don't end up with rocket coming down under power. Also, unlike many other altimeters, arming the Quantum is done via WIFI and is a separate step from powering on the Quantum. As part of the electrical design I'm including a small dual-pole-dual-throw (DPDT) switch located in the lower avionics bay between the Eggtimer Quantum and the sustainer igniter. I'm going to wire the DPDT switch so that when the switch is on (armed), it connects both wires from the Quantum to the igniter and when it is off (safe), neither side connects to the Quantum and the igniter leads are shunted together. Based on this, here is my current arming sequence:

    At the car
    Power on the GPS tracking system and confirm location lock
    Confirm sustainer safety switch (3S) in “safe” mode
    Power on the Quantum
    Verify proper settings (igniter delay, minimum safe altitude, minimum safe vertical velocity) on the Quantum based on the booster motor being used
    Connect sustainer igniter (outside of the motor) to the Quantum
    Switch 3S to “armed” mode
    Check connectivity on the Quantum (via WIFI)
    Switch 3S to “safe” mode - this shunts the igniter leads
    Disconnect the sustainer igniter
    (Note that the Quantum is on but has still not been "armed")


    At the pad
    Raise rocket on the launch rail
    Hold the stages apart with a short piece of 1” wooden dowel
    Confirm 3S in “safe” mode
    Connect the sustainer igniter to the Quantum
    Close/seal the lower avionics bay

    Insert sustainer igniter into the motor and secure it
    Join booster and sustainer by removing the dowel

    Arm Quark (sustainer deployment altimeter) via screw switch
    Insert igniter into the booster and connect it to the launch system
    Switch 3S to “armed” mode

    Verify connectivity on the Quantum
    Arm the Quantum
    Verify connectivity on the launch system





    I considered arming the Quark before inserting the sustainer igniter (in case the sustainer lights), but, in general I've been told that you shouldn't move deployment altimeters once they've armed. Also, if the sustainer does accidentally ignite, it should have the motor ejection to deploy the drogue and avoid a ballistic recovery.

    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  19. #19
    Join Date
    27th December 2014
    Location
    Seattle, WA
    Posts
    914
    I have seen one shred due to short couplers. IIRC, it was a 4" rocket with a 2" overlap. The rocket did a couple of really nice shimmies off the pad and then folded over under thrust. I don't know how that coupler overlap got past the SLI safety inspections.
    NAR L1 "Cheeto Dust", scratch 54mm, H54R (before it became a G54), Mansfield, WA
    L2 "Arc Light", Madcow 2.6" Arcas, J285CL, Mansfield, WA, recovery by snowshoe

  20. #20
    Join Date
    11th October 2017
    Posts
    23
    I've never been querried about coupler overlap.
    I'm currently designing a 6" blue tube and I'm planning to have 5-5.5" overlap on the couplers.
    This is ~0.8 caliber and my experience with 4" is that ~0.75 caliber works well.
    Any thoughts?
    Regards, Rich
    NAR 59673, L2
    TRA 17721, L2 via reciprocity with NAR
    NAR L1 - EZI-65 extended, dual deploy, I140
    NAR L2 - EZI-65 extended, dual deploy, J270

  21. #21
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119
    Quote Originally Posted by anbhtblr View Post
    I've never been querried about coupler overlap.
    I'm currently designing a 6" blue tube and I'm planning to have 5-5.5" overlap on the couplers.
    This is ~0.8 caliber and my experience with 4" is that ~0.75 caliber works well.
    Any thoughts?
    In general the rule I always hear is 1 caliber on each side, but, I see many commercial nose cones and electronic bays that only provide a little less than that. For example the electronics bays for 4" from LOC Precision are 8" couplers with a 1" switch band and their 7.5" nose cones only have a 5" shoulder. I am not an expert on this, but, in my opinion I'd think that if the rocket is not pushing limits and the coupler is strong and fits well you should be okay with 5.5" or maybe even 5" on a 6" rocket.
    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  22. #22
    Join Date
    11th October 2017
    Posts
    23
    Thanks for the feedback. I'm currently feeling comfortable with the design choice.

    Regards, Rich
    NAR 59673, L2
    Regards, Rich
    NAR 59673, L2
    TRA 17721, L2 via reciprocity with NAR
    NAR L1 - EZI-65 extended, dual deploy, I140
    NAR L2 - EZI-65 extended, dual deploy, J270

  23. #23
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119
    Today I started cutting the fin slots in the booster of this rocket. This is my first time cutting slots as the previous rockets I've built had the slots already cut. I'm using a router and jig similar to (but not as refined as) the one found on John Coker's site (http://www.jcrocket.com/finslots.shtml). I'm using a 1/4" up-cut router bit which fits nicely with the 1/4" plywood I'm using for the fins. So far it seems to be working well. The edges are just a tiny bit fuzzy, but, nothing that can't be fixed with a quick bit of sanding. Also, the ends of the slots end up round, so, I used a sharp knife to square them off. Here's a picture:Click image for larger version. 

Name:	first_fin_slot.jpg 
Views:	86 
Size:	70.3 KB 
ID:	335271
    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  24. #24
    Join Date
    23rd July 2011
    Location
    Butte, MT
    Posts
    2,550
    Quote Originally Posted by kswing View Post
    Today I started cutting the fin slots in the booster of this rocket. This is my first time cutting slots as the previous rockets I've built had the slots already cut. I'm using a router and jig similar to (but not as refined as) the one found on John Coker's site (http://www.jcrocket.com/finslots.shtml). I'm using a 1/4" up-cut router bit which fits nicely with the 1/4" plywood I'm using for the fins. So far it seems to be working well. The edges are just a tiny bit fuzzy, but, nothing that can't be fixed with a quick bit of sanding. Also, the ends of the slots end up round, so, I used a sharp knife to square them off. Here's a picture:Click image for larger version. 

Name:	first_fin_slot.jpg 
Views:	86 
Size:	70.3 KB 
ID:	335271
    Nice job on cutting slots!
    Youíre probably better off leaving the ends of the slots round. A squared off slot results in stress riser at the corners, an area where stresses are greatly concentrated.
    If you leave them round you can either make the slot slightly longer or you can sand the corners off the fin tabs.


    Steve Shannon
    Steve Shannon
    L3CC, TAP, Director, Tripoli Rocketry Association

  25. #25
    Join Date
    26th November 2009
    Posts
    5,214
    Quote Originally Posted by Worsaer View Post
    I have a lot of experience with Blue Tube, and it works well for me. Cutting with a compound mitre saw works great.
    I gotta get me one of those compound mitre cutter saw thingies.
    Also gotta get something set up to slot tubes in a straight fashion I can be sure of. Kurt

  26. #26
    Join Date
    15th October 2016
    Location
    Huntsville AL
    Posts
    2,140
    Quote Originally Posted by ksaves2 View Post
    I gotta get me one of those compound mitre cutter saw thingies.
    Also gotta get something set up to slot tubes in a straight fashion I can be sure of. Kurt
    I need something too. I've got a boattail to slot that's mocking me from my closet. Just need to talk my way into the good graces of a club member with a mill.

  27. #27
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119
    Quote Originally Posted by Steve Shannon View Post
    Nice job on cutting slots!
    You’re probably better off leaving the ends of the slots round. A squared off slot results in stress riser at the corners, an area where stresses are greatly concentrated.
    If you leave them round you can either make the slot slightly longer or you can sand the corners off the fin tabs.


    Steve Shannon
    Thanks for the tip....I think I'll leave the next set round and round off the fin tabs to match.


    As far as tools go, they are very helpful sometimes. I also do some woodworking, so, I already have a some of the tools needed. I'm using a fine crosscut blade on the compound mitre saw and it works well for tube cutting (and moldings). The fin jig I'm using is the kind where the router rides on a sled down the length of the tube. I've made the frame out of 1" pine and the sled out of 1/4" MDF and I use a spring clamp as my stop block. I check my alignment before cutting by dipping the router bit in finger paint and then lowering it (without power) down to the tube.
    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  28. #28
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119
    I made some progress on this rocket over the past few days. I cut all of the fin slots on the booster and I've cut out two of the four fins for the booster. I'm starting to really appreciate how nice and convenient it is to build a kit that already has the tube slots and fins cut. The booster tube shifted/rolled a bit (about 1/8") while cutting one of my fin slots, so, I had to go back over it with the router to get one edge straight and I'll have to fill the gap with epoxy or cover it with a fin fillet. It shifted because I didn't have the tube clamped as tightly as it should have been while routing. I learned my lesson and the others are all nice and straight.
    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  29. #29
    Join Date
    16th March 2016
    Location
    Virginia
    Posts
    119
    I've cut out all four fins for the booster, so, soon I'll be able to start working on the MMT and fins for the booster.

    Also, people have asked, so, below are some pictures of my tube slotting jig. It isn't pretty but it works. The sides/rails of the jig look a bit curved-in because they are. Rather than ripping boards to 5" tall for the sides, I ended up gluing together two 1"x3" boards (whose actual dimensions are 3/4" by 2 1/2") using biscuits and the biscuit slot cutter was aligned a bit crooked so the two boards had a bit of an angle between them. They are still parallel at the bottom and at the top, so, it didn't really make a difference.

    Here's a tube in the jig - underneath the tube is duct tape to keep it from moving:
    Click image for larger version. 

Name:	jig_with_tube.jpg 
Views:	52 
Size:	84.3 KB 
ID:	335977

    Here's the router sled - a bit of extra 1/4" plywood was needed so I could counter-sink the router mounting screws:
    Click image for larger version. 

Name:	router_sled.jpg 
Views:	46 
Size:	120.4 KB 
ID:	335978

    Below is the sled on the base. The small board sticking up on the left was used to align the router sled with the end of the jig. I put a spring clamp on one of the rails on the other side of the router to act as a stop for the sled
    Click image for larger version. 

Name:	sled_on_jig.jpg 
Views:	49 
Size:	105.4 KB 
ID:	335979
    Ken
    Northern Virginia
    TRA# 16215
    L2 - 11/19/2016

  30. #30
    Join Date
    15th October 2016
    Location
    Huntsville AL
    Posts
    2,140
    Good jig.

    What do you do to ensure the slots are 90deg?


Similar Threads

  1. Help on selecting a first two stage high power rocket kit
    By Bobfly in forum High Power Rocketry (HPR)
    Replies: 227
    Last Post: 2nd February 2018, 03:11 AM
  2. High Power 2-Stage build thread
    By csoechtig in forum High Power Rocketry (HPR)
    Replies: 41
    Last Post: 19th May 2014, 12:19 PM
  3. 2 stage Mid/High power pictures
    By conman13 in forum The Watering Hole
    Replies: 0
    Last Post: 11th April 2014, 01:43 AM
  4. 2 Stage Minimum Diameter High Power How To?
    By Lentamental in forum High Power Rocketry (HPR)
    Replies: 17
    Last Post: 14th June 2011, 04:29 AM
  5. 2 Stage - High Power - Where to Start?
    By valkrider15 in forum High Power Rocketry (HPR)
    Replies: 19
    Last Post: 1st June 2005, 11:37 PM

Posting Permissions

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