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  1. #211
    Join Date
    18th January 2009
    Location
    Virginia - Central
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    Thanks for the report and post flight update.
    This build has been a very worthwhile experience for me, looking at the entire progression from concept to finish details, and had many different directions to pursue based on materials and methods available.
    I'm happy to see you were able to get a flight done before moving down south to fly with our Aussie friends.

    Love to see a list of basic overall specs on the project for the post flight on flight #1 ......motor config. electronics selection for all flight parameters/launch thru air start thru recovery - (know I can go through the build thread but I might be missing something).
    Even the details on ignitor and recovery charges.

    This was a very well thought out project from the build techniques to systems selection and will be a favorite thread for future reference.

    Last edited by MaxQ; 27th November 2017 at 04:54 PM.
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  2. #212
    Join Date
    29th August 2015
    Location
    Pittsburgh
    Posts
    189
    Next up, flight line.

    For the main motor, I was using an Aerotech 75mm L1420R with 4xCTI 38mm I55. I'd originally planned a CTI motor for the main, and had it, but wound up using it for another flight earlier this summer. I chose the Aerotech for availability, with similar specs, but hadn't considered the red flame. It was spectacular, but drowned out the clusters. When they flew, the only reason we know they lit was the long burn. I think a CTI classic would have had better effect but there it is.

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    Taking it to the flight line, we had problems loading it onto the rail guide. While trying to get the parts to mate, we'd forced the forward rail buttons out of alignment. A smack of a rubber mallet later, we were ready for flight. This is definitely a Plan B rocket.

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    Thanks to MaxQ, you've seen the video. It was an impressive flight to watch!

    The clustering was mostly successful. 3 out of 4 burned, but as I mentioned they were hard to spot due to the bright red flame of the main motor. I'm not sure what happened with the fourth motor. The igniter was still in place, and hadn't fired at all. I had redundant timers so it shouldn't have been a problem. As I mentioned earlier, the switch on my continuity checker was damaged so I wasn't able to check that before flight. I haven't traced the wiring yet for reasons you'll see in the next post.

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    Despite the uneven thrust, there was no noticeable problem with a flight that was nice and straight. The main popped at apogee and it slowly drifted into the middle of the field for an easy recovery.

    David Carter
    NAR 98850, TRA 16834, Level 3
    http://www.psc473.org/ http://urrg.us/

    90% of rocketry is sanding! (And a little bit of cursing...)

  3. #213
    Join Date
    29th August 2015
    Location
    Pittsburgh
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    189
    It didn't land upright, but it was a nice gentle landing

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    I even got to take home some fertile soil!

    There was some damage. One part that didn't surprise me was the clustering electronics. This stuck up way too high to give me access to the switches, and I fully expected the shock cords to catch on it and destroy it. I fully expected a redesign before any following flights.

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    The corrugation at the top of the S-IB stage was also damaged. This was just self adhesive paper and is easily replaced. I had thought about putting a thin fiberglass layer over that, and I think that ultimately would be a wise idea.

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    The most serious problem though was a zippering of the inner blue tube. That I hadn't expected. That stuff is strong! Especially with the deployment of the main at apogee this was a surprise. It may also be the one problem that keeps it from flying again without major repairs.

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    Another piece that was damaged happened before flight. It toppled off of a high table and one of the printed plastic pieces snapped. It was an easy fix but in the process the small section of body tube got punctured. Yes, I'm that much of a klutz. Again an easy fix except that in anticipation of my move I gave all of my unused body tubes and parts to a friend in Washington DC. So no fix in time for flight. Le sigh.
    David Carter
    NAR 98850, TRA 16834, Level 3
    http://www.psc473.org/ http://urrg.us/

    90% of rocketry is sanding! (And a little bit of cursing...)

  4. #214
    Join Date
    18th January 2009
    Location
    Virginia - Central
    Posts
    4,005
    Where there is a will, there is a way.
    Sounds like you had to improvise some, but way to go!
    Failure IS NOT an Option.

    Having to leave the states w/o getting this bird in the air would've been a bummer...
    Curious about the air start set up ...so when you have time.....
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  5. #215
    Join Date
    18th January 2009
    Location
    Virginia - Central
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    Quote Originally Posted by grandcross View Post
    The most serious problem though was a zippering of the inner blue tube. That I hadn't expected. That stuff is strong! Especially with the deployment of the main at apogee this was a surprise. It may also be the one problem that keeps it from flying again without major repairs.
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    Zippering around the top of the blue tube ...looks minor but wow, I wouldn't have thought that would happen, esp. with a lower speed apogee deployment.
    Can you tell us where the anchor point for the main shock cord is...down in the length of the core tube it appears...I've been pondering where/how to make strong anchor points inside the shell/airframe...was thinking of not putting it way down inside a body tube where I can't reach it and check for corrosion....thinking of making it anchor in the open like a traditional zipperless fin can.
    Appears the damage is mostly repairable/cosmetic.
    Last edited by MaxQ; 27th November 2017 at 08:11 PM.
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  6. #216
    Join Date
    29th August 2015
    Location
    Pittsburgh
    Posts
    189
    So, for lessons learned...

    One is the fiberglass. This was my first ever home made tube. I did not use enough layers and it was flimsier than I expected. I hadn't realised that fiberglass could dent! I had to fix one section with some epoxy clay. I was happy with my CF sections though and they had a stiffness I expected. I still needed the fiberglass though for the RF transparency.

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    For some sections, such as the transition, I would use a mandrel and make a mold. Next time.

    The 3D printed details worked well, but the big issue I have with them is CA glue. I wasn't happy with any of my joints. They were brittle and broke off easily. I don't know if using the 3D prints to create molds and then resin parts would have worked better. Comments?

    The inner compartments for the electronics worked exactly as designed. The altimeters worked fine. I had been hoping to create some standard wiring pieces using molex connectors but was having problems getting the pins to fit in the connectors. I still hope to get this solved as it would allow me to use my electronics interchangeably and move them from rocket to rocket with a minimum of effort. So back to a dedicated wiring harness.

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    The clustering electronics were a great idea, but as always the devil is in the details. A broken switch may have made the difference between the 3 motors firing and all 4 firing.

    The big issue I have of mating the two sections could have been prevented with a different assembly technique. When I put the 3 inch blue tube into the 5.5, I could have done it with the couple in place to ensure it aligned properly.

    So will it fly again? Probably, but not for a few years. I won't have physical access to it for a while but I definitely want to get this right. I may rebuild the upper section with a stronger FG tube and proper assembly to fix the alignment issues. I have a few years to consider options

    I've definitely learned a lot with this build. Maybe I'll build an SA-5 Saturn I while I'm in Australia...
    David Carter
    NAR 98850, TRA 16834, Level 3
    http://www.psc473.org/ http://urrg.us/

    90% of rocketry is sanding! (And a little bit of cursing...)

  7. #217
    Join Date
    29th August 2015
    Location
    Pittsburgh
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    189
    Quote Originally Posted by MaxQ View Post
    Where there is a will, there is a way.
    Sounds like you had to improvise some, but way to go!
    Failure IS NOT an Option.

    Having to leave the states w/o getting this bird in the air would've been a bummer...
    Curious about the air start set up ...so when you have time.....
    A few more posts since this one... let me know if there's anything specific you want to know.
    David Carter
    NAR 98850, TRA 16834, Level 3
    http://www.psc473.org/ http://urrg.us/

    90% of rocketry is sanding! (And a little bit of cursing...)

  8. #218
    Join Date
    29th August 2015
    Location
    Pittsburgh
    Posts
    189
    Quote Originally Posted by MaxQ View Post
    Zippering around the top of the blue tube ...looks minor but wow, I wouldn't have thought that would happen, esp. with a lower speed apogee deployment.
    Can you tell us where the anchor point for the main shock cord is...down in the length of the core tube it appears...I've been pondering where/how to make strong anchor points inside the shell/airframe...was thinking of not putting it way down inside a body tube where I can't reach it and check for corrosion....thinking of making it anchor in the open like a traditional zipperless fin can.
    Appears the damage is mostly reparable/cosmetic.
    Sadly it's not cosmetic. It's structural. Remember that this is essentially a structure within a facade. This is the mating point between the upper and lower sections. This would require removal down to at least the centering ring, but that leaves the section short about two inches. If I rebuild the upper section, as I'm considering, that won't be a problem but it would certainly be a challenging fix as it is. There's just too little tube to work with.

    My anchor point was the eye bolt attached to the motor. Any other solution would risk entangling either the upper or lower stuffer tubes. If I trim back to the centering ring zippering at this end shouldn't be a problem. I could always glass the other end.
    David Carter
    NAR 98850, TRA 16834, Level 3
    http://www.psc473.org/ http://urrg.us/

    90% of rocketry is sanding! (And a little bit of cursing...)

  9. #219
    Join Date
    18th January 2009
    Location
    Virginia - Central
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    Quote Originally Posted by grandcross View Post
    My anchor point was the eye bolt attached to the motor. Any other solution would risk entangling either the upper or lower stuffer tubes. If I trim back to the centering ring zippering at this end shouldn't be a problem. I could always glass the other end.
    Ok..so I got that....the zippered end of the core blue tube is where the forward section with the transition plugs into the lower section.


    Anchoring to an eyebolt on the motor...that has been a very effective way to do it.
    Most of my projects use the motor ejection well/end closure on the case as a last dich back up when the longer delay allows it...it has saved a rocket or two when a battery or electronics in the recovery subsystem failed.
    But moving to L3 in my case will eventually require I go full redundancy with electronic recovery - so I'll probably try an eyebolt on the end of a motor case soon enough.
    Some of the larger/length rockets I've done I've not particularly liked reaching down inside a long body tube for cleaning maintenance of the shock cord anchor point...and corrosion does mess them up over time.
    I was stuck trying to figure out where to put that load bearing anchor point because there isn't much room inside where the mating points of the airfame come together...but your way may be the way to go.
    Last edited by MaxQ; 27th November 2017 at 08:38 PM.
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  10. #220
    Join Date
    29th August 2015
    Location
    Pittsburgh
    Posts
    189
    Quote Originally Posted by MaxQ View Post
    Ok..so I got that....the zippered end of the core blue tube is where the forward section with the transition plugs into the lower section.


    Anchoring to an eyebolt on the motor...that has been a very effective way to do it.
    Most of my projects use the motor ejection well/end closure on the case as a last dich back up when the longer delay allows it...it has saved a rocket or two when a battery or electronics in the recovery subsystem failed.
    But moving to L3 in my case will eventually require I go full redundancy with electronic recovery - so I'll probably try an eyebolt on the end of a motor case soon enough.
    Some of the larger/length rockets I've done I've not particularly liked reaching down inside a long body tube for cleaning maintenance of the shock cord anchor point...and corrosion does mess them up over time.
    I was stuck trying to figure out where to put that load bearing anchor point because there isn't much room inside where the mating points of the airfame come together...but your way may be the way to go.
    For the 75mm motors, there is no ejection charge. Accessing the anchor bolt is easy... just remove the motor and attach/detach the shock cord.
    David Carter
    NAR 98850, TRA 16834, Level 3
    http://www.psc473.org/ http://urrg.us/

    90% of rocketry is sanding! (And a little bit of cursing...)

  11. #221
    Join Date
    29th August 2015
    Location
    Pittsburgh
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    189
    And finally, the flight stats...

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    David Carter
    NAR 98850, TRA 16834, Level 3
    http://www.psc473.org/ http://urrg.us/

    90% of rocketry is sanding! (And a little bit of cursing...)

  12. #222
    Join Date
    18th January 2009
    Location
    Virginia - Central
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    4,005
    Quote Originally Posted by grandcross View Post
    For the 75mm motors, there is no ejection charge. Accessing the anchor bolt is easy... just remove the motor and attach/detach the shock cord.
    Too bad I did my design with a 54mm core motor.
    The internal spacers looked a bit fragile when I drew up the fin can cross section with a 75mm core motor.
    But I probably can get a eyebolt end closure for a 54mm. case.
    I think Loki had them for even smaller motor cases.
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  13. #223
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    29th August 2015
    Location
    Pittsburgh
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    Starting to think of ways to fix this. Stay tuned for updates in a few years when I return to North America!
    David Carter
    NAR 98850, TRA 16834, Level 3
    http://www.psc473.org/ http://urrg.us/

    90% of rocketry is sanding! (And a little bit of cursing...)

  14. #224
    Join Date
    27th August 2011
    Location
    NJ
    Posts
    2,725
    Dave,
    Your Saturn 1b is a magnificent build....amazing that she flew so stable with on of the smaller motors not firing. The video is just spectacular. Brings tears to the eyes to see the damage..but if anyone can repair it, it would be you. Also wanted to wish you good luck with your upcoming move!

    Rick

  15. #225
    Join Date
    27th January 2009
    Location
    Oregon
    Posts
    2,171
    This mirrors my experience in my hobbies, that no matter how much thought or planning goes into a project, nothing ever works as it should and a 5 minute job will take 2 hours, the less time I have, the longer it will take....

    Glad it flew so well!

    Frank


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