This time we tested a 6 grain 75mm motor. The same formula as the last stuff we have done before. Data Graph is attached, thrust is on the left, in Newtons, pressure on the right in PSI.
Just a couple of observations from the data. Big spike in pressure and thrust in the middle of the burn. I am speculating that this is due to a void in the grain. Density numbers from the casting sessions have been good. In the mid 90% range.
A bit of erosive burning at the beginning of the burn. I may just leave this in, but I may not. If i decide to take it out, I'll increase the core a 1/16th of an inch, that should resolve that.
Pressures are a bit higher than I want, so I'll increase the nozzle throat a bit and run a bit lower KN.
Max KN for this motor was around 400. I got better than expected ISP for this burn. Bigger motors tend to have better ISP numbers, but this is higher than I would attribute to that. I suspect that my load cell calibration was a bit off. All of my test equipment is hand built by me. The load cell and load cell amp are custom pieces that I made. I am still perfecting the amp circuit.
I've got a movie of the firing, but its in .mov format, and I can't edit it right now. I may be able to get it done in the next few days, but I don't know for sure.
This static firing is in preperation for BALLS this year. Our little group of 4 people will be flying this and other motors at the event. I plan a commercial 2 grain 75mm motor (AMW L700), a 2 grain 75mm of my own formula, a 3 or 4 grain 75mm of my own formula.
One of my friend plan a commercial "M" motor for a certification flight on Friday, followed by a 5 grain 75mm of my formula if the cert is successful.
Another friend plans a two stage flight of a 6 grain 75mm in the booster, 5 grain 75mm in the sustainer for around 25K ft. Several 54mm flights (4 grain and 7 grain)
The other friend is planning several hybrid flights, including a 2 stage hybrid flight. His motor is unique and is patent pending! They come in around the large J to small K in total impulse.
Can't wait to get down there and fly. There should be some amazing stuff. One of the guys I know is planning a "Q" class flight. The motor is amazing...Total impulse 133000 NS, max thrust about 5200 Lbs burn time of 7.5 seconds...average impulse is 17500 N.
Static test again
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Ray
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Static test again
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Greg O'Bryant
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re: Static test again
Very nice burn Ray;
A Q sized engine! Are they planning on lunching a VW BUG?
A Q sized engine! Are they planning on lunching a VW BUG?
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Ray
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re: Static test again
That's flattering about the boosted dart thing...the motor with a bit larger core will be somewhat progressive. Shorten the grain a bit (like 4" instead of 5") and the curve will be "flat".
I can't wait to see the "Q" fly...should be more than impressive...even if the flight is less than optimal...
I've been to XPRS but not BALLS before. The pace will definately be slower, but each flight promises to be memorable.
I buy the liners and casting tubes as a pair from John Lyngdal. The casting tube is spiral wound cardboard and the liner is phenolic impregnated spiral wound paper. It works just fine in all the motor sizes I've tested so far. I see occasional burn through, or even a crack or two, but no damage to cases thus far. I'd say it meets my expectations. I'd like to do some end burners and moon burners some day, so I'll have to beef up the liner in some way. That's in the future though.
I have some propellants that I want to develop over the winter. I am in the process of machining a ballistic motor to do the charactarization. Hoping for some high solids designs to get the ISP up where I want it to be.
Working with a guy that used to be a propellant chemist at one of the motor manufacturers...he adds a lot to the knowledge base...
I can't wait to see the "Q" fly...should be more than impressive...even if the flight is less than optimal...
I've been to XPRS but not BALLS before. The pace will definately be slower, but each flight promises to be memorable.
I buy the liners and casting tubes as a pair from John Lyngdal. The casting tube is spiral wound cardboard and the liner is phenolic impregnated spiral wound paper. It works just fine in all the motor sizes I've tested so far. I see occasional burn through, or even a crack or two, but no damage to cases thus far. I'd say it meets my expectations. I'd like to do some end burners and moon burners some day, so I'll have to beef up the liner in some way. That's in the future though.
I have some propellants that I want to develop over the winter. I am in the process of machining a ballistic motor to do the charactarization. Hoping for some high solids designs to get the ISP up where I want it to be.
Working with a guy that used to be a propellant chemist at one of the motor manufacturers...he adds a lot to the knowledge base...
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Ray
- Posts: 187
- Joined: Thu Nov 11, 2004 12:48 am
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- Location: Washington State, USA
Re: re: Static test again
Well, they could.Greg O'Bryant wrote:Very nice burn Ray;
A Q sized engine! Are they planning on lunching a VW BUG?
I haven't seen the rocket they plan to put the motor in, but it promises to be just as impressive as the motor, which by the way is 8" diameter, about 8 ft long. 158 lbs of propellant. I'm guessing at a lift off weight of around 400+ pounds.
Rumor has it they are planning on about 75000 ft...I hope they make it, the guy is a good guy, I enjoy the heck out of his company (I pick his brain cause its so big when it comes to this stuff).