Top Secret....

Posted by Ethan Kosoof on July 7, 2008 at 5:07am

Hi Ya'll

I just got this in the mail the other day. Pictured next to that beast is a PML 2" Amraam for scale so you know how big this thing is. You'll have to wait and see if you wanna know what it's going in :)

Ethan

Comment by davetherocketguy on July 7, 2008 at 6:23am: It's a casing...DUH. But what motor...hmmm. Seeing how I have never flown anything larger than an H that means I have no clue. I am going to guess a CTI casing for an O5300? Regardless, that sucker is HUGE.

Comment by Peter Waithe on July 7, 2008 at 7:21am: My guess is a AMW case for the M2200.

Comment by Ethan Kosoof on July 8, 2008 at 4:10am: Close, but no banana!

Dave, its not an O5300...Although I'd love to get my hands on of them : )

Mr. Waithe, your pretty close! You've got the diameter right...Its not AMW though. Its not actually any brand it all so I guess that was kind of a trick question! Details to come.... :D

Comment by Peter Waithe on July 8, 2008 at 8:26am: OK, now you got my curiousity going.

Comment by Whitney Richard on July 9, 2008 at 10:36am: Looks to me like you are planning and adventure to the land of erosive burning!

Comment by Peter Waithe on July 9, 2008 at 11:33am: Whatever he is planning, it is going to be a way cool flight. I believe the diameter of an M is 6". Maybe he is planning a near minimum diameter M flight.

Comment by John Smolley on July 12, 2008 at 6:00pm: What a tease! Well the M mentioned is 3" diameter. The PML rocket is 42". Which just happens to be a little bit longer than the biggest commercial M made in 76--IIRC Jeff Taylor was selling 4' cases in 76 a while back. But people kept getting killed. Seriously, this would then appear to be oNe serious motor with a very high length/diameter ratio. This can be very good if treated properly, and very bad if not. One of the potential problems with these so-called fence post motors is a phenomenon known as erosive burning--what Richard is referring to.

For any unfamliar with the term, basically what that means is that the jet of hot gas lunging towards the nozzle (or upwards) accelerates the rate at which things get burnt.This creates greater thrust, but can also put huge stresses on the propellant grains. If things get out of hand, these motors usually come apart in a hurry--often by popping a closure. Frank Kosdon who was one of the first amateurs to come along and make real motors that burned APCP is famous for these kinds of motors. OK enuf history (and if I have any of this wrong, someone please correct me). When and in what will this be flying?

Comment by Ethan Kosoof on July 12, 2008 at 7:59pm: Ok...here is another bit of the story....its 48" long. Holds 43.5" of propellant.

I'm not making the propellant. I am only building the rocket it is going into. The only reason it is in my hands is for sizing purposes, and as a mandrel for the tubes. The propellant is being made by an experienced EX'er.

Comment by John Smolley on July 13, 2008 at 3:37pm: Hi Ethan. Chatted wih a compatriot of yours last night, ChrisN. Since you have confirmed the dimensions and used the word manfrel, don't think I'm giving anything away by saying this then amounts to neart a full M in a 3" min diameter rocket that should be capable of 40-50K feet. WOW! Keep us all posted as things proceed. Because the flight speeds will be >M3 this may be a case where high Tg epoxy is absolutely called for.

Comment by Peter Waithe on July 13, 2008 at 5:36pm: So I was close with a minimum diameter M project. What are the rest of the specs for this project? Length? Weight?