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Originally Posted by georgegassaway
I recall reading either in Stine's handbook, or in MRM, about a "Wada" device. I can't recall exactly what the device was called (maybe also an augmenter). But pretty much the same concept as the Kuhn augmenter. Pretty sure though, it predated Kuhn's. The impression I got about the Wada device was it only had a short distance of the motor sticking inside of it, say 3/4" of a normal 18mm motor, so not as much "kick" as using 2.5" of a motor casing length.
I would never, EVER, trust a 1/4" wide wrap of tape at the top of a motor (as described for Kuhn's), for a safe friction fit, to prevent the motor from getting kicked out.
Actually, may have read about Wada's in an article or report by Geoff Landis about pistons in the mid-70's.
The CMR Boom Tube came after others began to develop pistons. The boom Tube had a design flaw, where it was attached to a wooden block base, with a hole in the wooden block for a launch rod to slide thru. So, the piston sat off to the side of a launch rod on a normal pad (about 1.5 to 2 inches over), rather than the piston's core rod being mounted directly to a pad. This meant every time it worked, the offset acceleration force caused it to whip to one side, due to the lateral offset of the wooden base slid over a rod. I saw those things being used on serious contest models at NARAM-16 (my first NARAM), slid over a 1/8" rod and cringed as the models often tipped off for the very reason of the side-whip.
Doing some googling, I found this:
"Wes WADA introduced “Augmenter Tube” (essentially short “piston” without moving
parts) in his Research and Development report at NARAM-5, (Hanscom Field, Bedford,
Massachusetts, 1963)
Pretty interesting source for that quote, a very long dissertation by a top Russian FAI flier, Alexander Mitiuriev, aimed at the FAI S1 event (Altitude). It includes his compilation of history on pistons.
http://www.nar.org/wp-content/uploa...-2013-Rev-4.pdf
But it does not cover a lot of the in-between piston developments from Wada's, beyond the Closed Breech launcher dead-end for models, and then the ZVPL. As it is i'm impressed at the info he obtained and compiled like that.
In-between (early 1970's there were telescoping tube piston launchers, like BT-5 sliding inside of BT-20 (using AR-5/20 rings), a big stepping stone between closed breech and ZVPL. Telescoping were the first real pistons I used. |
George, Geoff Landis' had a report titled," The Zero Volume Piston Launcher or An Illustrated History of Closed Breech Launchers" in the May 1974 issue of Model Rocketeer. This was an expanded upon version of his MIT Con Proceedings paper," Building a Zero Volume Piston Launcher ", April 1973..
He had poor illustrations of several types of Piston launchers in both papers and in the 1st a drawing of Wes Wada's thrust augmenter from 1963. It basically looks like a piece of body tube, about the length of an engine, that has a nose block in one end of the tube. This is how I also thought it looked to me, from what I had read.
It was here that I first learned of the Kuhn Augmenter. As I posted it now appears that the Kuhn Thrust Augmenter evolved fairly quicky and with about a year became the CMR piston Launcher the "Boom Tube". The 1984 R&D report that I found described to a T the internal workings of the Boom Tube connection, and coincides with the Kuhn Thrust augmenter. It appears Howard just merged the two devices into a better one.
But recently, I got hold of a 1963 copy of the American Aircraft Modeler, and it shows a completely different design drawing by G.Harry Stine of Wes Wada's piston design.
This drawing shows the body tube/nose with an engine enclosed, sitting in a longer, bigger outer tube with the fin can and fins sitting on top of the outer tube and as the model accelerates out of the piston tube it catches the fin can/ fins body tube on the way up.
What is funny about this is, Trip Barber shows that same type of piston tube in a diagram in his January 1974 MIT Journal article, "Pressurization Effect Launchers" as a "blow-thru" piston launcher.
There's no doubt in my mind that Geoff Landis designed and build the 1st ZVPL, but he designed his zvpl from a piston Launcher that he had seen earlier by a person named George Helser in August 1971 at NARAM-13. At this same event, Andrew Bennet was using a similar, if NOT identical Standard type piston launcher as George Helser.
In fact, Andy Bennett presented a paper on his Standard Piston which is identical to George Helsers's Standard Piston, at MIT in March 1972.
Either way, Geoff was present at Both NARAM -13 in August 1971, and at MITCON in March 72 so there's ample evidence that he saw both Standard Piston Launchers from both people.
George had designed a piston launcher that is and was called the Standard Piston Launcher. This was a small tube inside a bigger tube, whereas the ZVPL is a big tube over a smaller tube.
There's more to it than that, the Standard piston launcher had considerable open space to fill before it would pressurize, while the ZVPL of course had zero or minimum volume to pressurize.
Geoff Landis May 1974 article shows 2 iterations of his ZVPL. It shows the first version which he also showed in the March 1974 report, but it also shows the ZVPL that we all know about today. The V1 used a string as a piston stop to prevent the piston tube from separating from the piston rod, while his V2 used a hard stop piston stop against the piston head.
The piston stop V2 model was effectively analyzed by Bauer,Prozio & Thoelen in March 1974 with their report, " Optimization of the Zero Volume Piston Launcher. "
This is just the first 5 years of Piston Tube development. I believe a Richard Essman back in 59-62 used a thrust augmented, but I'm going to have to go back and find the entry. And then I have to move forward to the mid-80's with Jeff Vincent and Chuck Weiss development of the floating head piston launcher now banned from FAI competition because it was just to **** effective and we can't have the American flyers using it to win Gold medals. (Plus it might hit somebody in the head on the way down).
And then there's your brass head piston launcher. I believe you got that idea from seeing a piston from a competition at the Internats?
My plans are to develop this into an article publishable in Sport Rocketry sooner than later.
and yes George I read that piston history by Alexander Mitiuriev. That's what got me started on this in the first place because I think it's kind of strange that a Russian would supposedly know more about our American model rocket piston development history than we do ourselves, so I decided to create the definitive reference.
PS George : I have 2 photos and text from a RC BG by Bernie Biales that I want to give you for your RC BG history page. I need some place to send them to. dm me a email address?