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Motors and Motor Development
Mike,
When I worked at Enertek for Lee Piester in 1987-88, I discovered a box of random rocket motors in the office closet. One of the motors was a bare fiberglass casing with graphite nozzle. It was labeled "Dorffler G Motor". All I have been able to find out about it was that it was made in the mid/late 1970s and that it might have used leftover Enerjet motor components. I was wondering if you could provide me with some history about this motor. Thank you. Bob Sanford |
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Bob - ya know, the more I read the questions here, I'm beginning to learn where all my missing stuff got to! How in the world did my motor protos end up at Centuri I ask? And then I learn Bob Kaplow has at least one of Ed and my 'Brown-Dorffler' motors. You guys collectively have have more of my stuff than I do! Geeezo. Anyway, Ed and I never had an approved budget in our earliest work with composite motors. We made motors and propellant from what we could essentially find laying around. After Enerjet ceased operations the remaining casings, nozzles, head enclosures, and other stuff was shipped and stored at the Estes plant. Well, Ed and I made an effort hide most of it so it wouldn't somehow be destroyed. In affect we stole it and moved it to an area where nobody would find it. We must have had well over 1,000 of both E and F fiberglass casings and more than enough nozzles, both graphite and phenolic, to almost go into motor production. We started making clones of the Enerjets as the fastest way to get on a learning curve. First we made them in the same way Irv Wait did, then we developed our own techniques. The motor you have is one of many of those learning curve motors we made. Then as we took each part or process as far as we could, we chinked over to another aspect of motor design. One of the coolest things about one of those Enerjet motors was that they lit up like a flashbulb right at burnout. The propellant was loaded into the casing without a liner, which meant that it came i n direct contact with inside of the casing wall. And because they burned outward from the cenetr core, the flame head contacted the case wall at the end of the burn. And if you got a little careless and didn't get the propellant loaded just right you could end up with a ring of fire on the inside of the casing right at the front of the nozzle face as well as at the head enclosure. Ed and I worked with many propellants over the years. Loading the double-based motors taught me well not to ignore wearing rubber gloves handling the proellant. On one occasion I got one of the biggest headaches I had ever had because I didn't think holding onto a grain bare-handed for a minute or so would be that big a deal. Wrong. |
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Mike,
Thanks for the information about the motor I found. A few more motor questions: 1) In 1994, Estes released a new E2X kit called the Manta (Parasite B/G). I bought one and the packaging/box listed C10 motors for use with this model. Also, I heard of a C4 motor around the same time. What happened to these two motors? 2) The 1993 catalog introduces the Pro Series Terrier/Sandhawk and Jayhawk scale models. The motor listings for these two kits refer to E15 & E30 motors. Was this E15 the black powder motor which was released? What about the E30 motor? 3) At several hobby shows in the early 1990s, I saw a sign announcing that Estes would have composite motors. This was many years before North Coast Rocketry and the F62 motor. I have attached a picture of the sign. What is the story behind the product mentioned on the sign? Thanks for your time and I look forward to your answers. Bob Sanford |
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The D12 is a detuned D13. The E9 is a detuned E15. The E30 and the D20 I saw fly in person were never released but a bunch of prototypes were made. The detuning of motors are done because BP motors continue to cure after shipping and performance varies quite a bit with temperature and humidity. The D13 had a fairly high failure rate in the west but not so much in the south and east.
I am not subject to Estes NDA. The Pro series ended up being released as clustered 24mm rockets. The F62 internal geometry was an exact copy of the U. S. Rockets F40/F80. As such, one grain is an E, two an F, and three a shippable G. It appears Estes tried to get CPSC to accept G's, and when not, they were not released even though DOT and NAR certified already. Jerry |
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Oh, the D13 definitely had a high failure rate in the South too! I have film!
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Roy nar12605 |
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Sorry Jerry, as the primary designer of the F62 I can tell you most assuradly I did not copy any U.S. Rockets motors, or any one else's for that matter. The internal ballistics of the 'Smokey Sam' propellant dicatated the internal grain geometry just as all propellants do. |
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Mike. what do you think of a BP re-loadable.
I understand that there would be at least 1 initial detriments: CPSC would not recognize this as a model rocket because of the metal casing; therefore only adults could purchase and use. Ok so Estes makes a product for adult only. It sems to me that Estes could use its current investemnet in its Mabel technologies: you just press a propellant grain/delay/smoke train/ejection charge/clay containg cap into a smaller length and diameter paper casing. Using a metal casing would allow you to burn the BP propellant at much higher chamber pressures resulting in much higher Isp's. Nozzles could be single use or multi-use perhaps and replaceable. looking forward to your responses. terry dean what advantages/disadvantages pros/cons do you see to such a product?
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"Old Rocketeer's don't die; they just go OOP".....unless you 3D print them. |
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Mike - the world needs F62 Darkstars! - OK I need F62 Darkstars! It is the finest model rocket motor ever, you need to find someway of bringing it back.
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Did the chicken really cross the road, or did the road move beneath the chicken? Albert Einstein You Can't break the laws of physics but they can break you. Christine McKinley Dale Greene Mentor, Penn Manor Rocket Club VISIT SPAAR 2010 Calder Cup The Old West 2009 Calder Cup " Speaking the Truth in times of universal deceit is a revolutionary act. " George Orwell |
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