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  #11  
Old 05-04-2009, 09:15 AM
Chas Russell's Avatar
Chas Russell Chas Russell is offline
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Carl,
You mentioned that the casing walls are holding up to the burn. Will a six-second delay burn possibly cause too much erosion? I know that it is dynamically less damaging, I was just thinking about the heat. Perhaps the char from the propellant burn will provide some heat protection.

Guess you'll just have to make and test a few.

Chas
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  #12  
Old 05-04-2009, 10:13 PM
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chanstevens chanstevens is offline
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Quote:
Originally Posted by Carl@Semroc
Those are the results from the second prototype A1.5-0 10mm engine! A little too hot for an A, but that was improved with third which was 2.50N 1.51N and 1.66s. There still is .6" left over in the tube for delay and EC. That will probably limit a full A to about 6 seconds max.

The thin wall cases do hold up. I was afraid that since they are about .050", they would cato or burn-through. So far, all the tests are positive.

An old Estes A8-3 on the stand was 2.2N-s with a .52s burn.

There is still a lot of work to do!


A 6-second A? I'll fly a bunch, but am not sure I've got the attention span to track anything that flies on one of your C's when you release them. You'll certainly never get these into Wal-Mart, so that Estes acquisition might not be such a hot idea.
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  #13  
Old 05-04-2009, 10:31 PM
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Quote:
Originally Posted by foose4string
Very cool.

I have a generic question relating to your motors(this may have been discussed already-not sure).... what is the process for making the nozzles and how are were they made for the prototypes? This question has nothing to do with the prototype test results, I'm just curious how certain aspects of the motors are(or will be) manufactured since I don't know much about the process.
The nozzle is made of clay. It looks like kitty litter before it is compressed. When it is pressed, like the black powder and delay, its density almost doubles and it is a very hard slug. The divergent cone and throat are pressed into the base of the clay by a steel drift or die to give it the correct shape.
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  #14  
Old 05-04-2009, 10:32 PM
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Quote:
Originally Posted by Initiator001
Great news, Carl!

Please be sure to get your motors California certified so I can fly them.

Bob
We will HAVE to get them CA certified or no one can fly them in competition!
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  #15  
Old 05-04-2009, 10:34 PM
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Quote:
Originally Posted by chanstevens
A 6-second A?
That is 6-second delay. The burn time is about 1.6 seconds.

I am looking at a 2 second delay before the actual burn for an upper stage engine. The booster would ignite the upper stage, then drop off. The sustainer would produce just enough gas to drop the base pressure for 2 seconds or so to allow it to act as a boosted dart, then after the velocity burns off some, the actual burn would start. For B altitude, I have always wondered if this would help. I was working on that with 13mm engines in the early 70's when the rug got pulled.

I suppose I could fly the combination in Rocksim, but it is not the same without the sulfur smell.
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  #16  
Old 05-04-2009, 11:08 PM
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Quote:
Originally Posted by Carl@Semroc
...

I suppose I could fly the combination in Rocksim, but it is not the same without the sulfur smell.

Rocket simulations - who needs 'em? The guy over in the "Ask Mike" forum said that HE don't need no stinkin' sim program, so why should any of the REST of us use one!

Simulation software - feh!

Just set them up on Semroc's remote corporate rocket range, retreat into the heavily-reinforced blockhouse that you have on site, press the button, and see what happens!



MarkII
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  #17  
Old 05-04-2009, 11:39 PM
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Originally Posted by Mark II
Rocket simulations - who needs 'em? The guy over in the "Ask Mike" forum said that HE don't need no stinkin' sim program, so why should any of the REST of us use one!
I was wondering if I was the only one that saw the humor in that.

When Telex hired me in 1971 as a final test technician, I convinced the guy in personnel that I knew a lot about logic design because I had read a few books. I aced the test and started the next day. My new supervisor told me that my oscilloscope was on order. I told him, essentially, that i did not need no stinking scope; I could see ones and zeros with a meter, if he just told me how many volts a zero was and how many volts a one was. He went over to his office, pulled a few hairs out, and came back and asked me if the guy that hired me had told me about the 90 day probation period. He suggested that if I really did not know how to use a scope, I had better learn pretty D**N quick.

From that point on, I have always been willing to add any new tool to my toolbox and learn how to use it. All the people that I worked for initially and that I supervised later were stuck in the same groove of "I don't need anything that I did not have 20 years ago."

I can look at a box and tell you how much it weighs, but the post office prefers that I use a "stinkin" scale as a cross-check!
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  #18  
Old 05-05-2009, 01:00 AM
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Quote:
Originally Posted by MarkII
Rocket simulations - who needs 'em? The guy over in the "Ask Mike" forum said that HE don't need no stinkin' sim program, so why should any of the REST of us use one!


Quote:
Originally Posted by Carl@Semroc
I was wondering if I was the only one that saw the humor in that.


Being one of the primary targets of that short-range tactical strike I thought it was kinda funny, too. Sad, but funny...

Carl, what sort of final weights (with delay charges loaded) are you expecting the complete engine to reach? I'm trying to force-feed your numbers into the RockSim engine editor, so I can start excessively relying on my simulations of this engine.
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  #19  
Old 05-05-2009, 01:14 AM
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Quote:
Originally Posted by CPMcGraw
Being one of the primary targets of that short-range tactical strike I thought it was kinda funny, too. Sad, but funny...

Carl, what sort of final weights (with delay charges loaded) are you expecting the complete engine to reach? I'm trying to force-feed your numbers into the RockSim engine editor, so I can start excessively relying on my simulations of this engine.
Just estimates:

Casing and nozzle 1.5g
BP for A 3.3g
Delay 5 sec 1.0g
E/C & cap .7g


So:
A1.5-0 about 4.8g + about .3g extra BP for blow-through
A1.5-5 about 6.5g
2-A1.5-5 about 6.9g (2 second delay before BP)

Booster will probably have larger spike than sustainer.
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  #20  
Old 05-05-2009, 01:21 AM
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Thanks, Carl!
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