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  #1  
Old 01-10-2011, 12:44 PM
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Carl@Semroc Carl@Semroc is offline
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Default New engine type

In our final days of Semroc 1.0, we were working on several new types of engines. One broke the propellant into sections divided by delays and another had an initial delay followed by propellant then the normal end delay. The first type sounded like a multistage but had higher altitudes. The second was for an upper stage sustainer.

The booster would ignite the delay as it staged. The sustainer would continue for 1 or 2 seconds coasting and slowing until the main propellant started. At this point it was much higher and going slower (with much less drag) as the main charge started. The sustainer did not have an initial spike so it burned at a lower thrust for a longer period. The slight pressure should also help base drag during the delay during staging.

I ran Rocksim on an A1.5-0 to A1.4-4/7 combination on a 10mm 2 stage and it sims to almost 2800 feet(850 meters). The NAR record is 731 meters for B altitude. The -4/7 means it delays 4 seconds before main burn then a 7 second delay before ejection. This is not for the faint of heart or heavy rockets (or non-vertical flights!)

A1.5-0 to A1.4-4/7

BECO v=350 ft/sec alt=300 ft
- 4 second delay - - 0 delay -
SEIGN v=72 ft/sec alt=1100 ft
SECO v=600 ft/sec alt=1800 feet
Apogee v=0 ft/sec alt=2800 ft

A1-5-0 to A1.5-7

BECO v=350 ft/sec
-no delay-
SEIGN - same as BECO
SECO v=700 ft/sec alt=1300 ft
Apogee v=0 ft/sec alt=2300 ft (500 feet less altitude)

Problem is in seeing a 10mm rocket at 2800 ft!
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  #2  
Old 01-10-2011, 12:56 PM
zog139 zog139 is offline
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NARAM-40 had "B" altitude as an event. The engine of choice was the Apogee 10.5mm B2-7. They flew great, but tracking them as you mentioned was difficult. The motor you describe in your post sounds fascinating, I would think it might work easily for Altitude events ( tracking) however it might work in other events such as boost glider ?


I volunteer to beta test :-)
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  #3  
Old 01-10-2011, 10:24 PM
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Sounds interesting, thanks for sharing Carl. When the sustainer ignited, did the initial delay provide sufficient pressure to separate the booster?
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Old 01-11-2011, 11:12 PM
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Gus Gus is offline
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Carl,

At WSMC last summer the Chinese were flying two step single stage motors. High initial thrust followed by slow sustain. They sounded like staged separate motors but were just single motors with two different steps to their burn. Very interesting sounding.

I presume they were using them in various events but I personally only witnessed them being used by the junior team in parachute duration (they flew in the lane next to Emma with the US juniors). The Chinese didn't do particularly well in that event but there was so much lift that day that it just didn't matter what motor you used. Realistically, the parachute and streamer duration models are so lightweight that you don't really need any increased thrust at liftoff. With pistons even an A1 will get up to stability speed by the time it leaves the piston.

I know these 10mm motors are just thought experiments at this point but our biggest disadvantage on the US Spacemodeling team is that we don't have 10mm motors to develop and practice with (at this point we don't even have a 13mm booster motor to practice with). Our best altitude flight this year in S1b (B-altitude) was over 100 meters below the Slovenian winner. So we could REALLY use some American 10mm A 1.5s.

Steve
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Old 01-13-2011, 09:41 PM
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GuyNoir GuyNoir is offline
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Quote:
Originally Posted by Carl@Semroc
The booster would ignite the delay as it staged. The sustainer would continue for 1 or 2 seconds coasting and slowing until the main propellant started.


Alan Jones, Bob Kaplow's old teammate, did an R&D on delayed staging for NARAM-30 in Huntsville. He also helped his nephews fly D Altitude using the techniques outlined in his report. If memory serves me right, he did C6-3 to C6-7 staging with some Centuri Sure-Shot wick in the upper stage, and pretty conclusively proved that having a delay between staging was a good thing.
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  #6  
Old 01-13-2011, 09:47 PM
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Quote:
Originally Posted by PaulK
Sounds interesting, thanks for sharing Carl. When the sustainer ignited, did the initial delay provide sufficient pressure to separate the booster?

It did with 18mm engines. We might have to dope the entrance of the A1.4 with BP since it has a .06" throat and delay does not ignite as easily as BP. It will be fun playing with it!
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Old 01-13-2011, 10:01 PM
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Quote:
Originally Posted by Gus
Carl,

At WSMC last summer the Chinese were flying two step single stage motors. High initial thrust followed by slow sustain. They sounded like staged separate motors but were just single motors with two different steps to their burn. Very interesting sounding.

I presume they were using them in various events but I personally only witnessed them being used by the junior team in parachute duration (they flew in the lane next to Emma with the US juniors). The Chinese didn't do particularly well in that event but there was so much lift that day that it just didn't matter what motor you used. Realistically, the parachute and streamer duration models are so lightweight that you don't really need any increased thrust at liftoff. With pistons even an A1 will get up to stability speed by the time it leaves the piston.

I know these 10mm motors are just thought experiments at this point but our biggest disadvantage on the US Spacemodeling team is that we don't have 10mm motors to develop and practice with (at this point we don't even have a 13mm booster motor to practice with). Our best altitude flight this year in S1b (B-altitude) was over 100 meters below the Slovenian winner. So we could REALLY use some American 10mm A 1.5s.

Steve

I remember a long 18mm D (4.5") that I pressed with four B charges with a 1-2 second delay between each charge. I had an external DECAP to provide the final delay and ejection charge. I placed a 1 oz charge of KCLO3 and aluminum dust as the "recovery device" and fired it at night in a thunderstorm. When the flash lit up the sky above the lower clouds, the sound took almost 5 seconds to reach the ground. I fired one earlier in the daytime and never heard the third and fourth charges and never saw it again.

We really want to be able to supply 10mm A1.5's to the USA team! In fact competirion is the primary reason for tooling for 10mm since it is not a "mainstream" engine.

I just finished reading the SR article on the WSMC. I would have loved to be there cheering Emma and the other youth. They all looked so happy and are all winners.
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  #8  
Old 01-14-2011, 08:43 AM
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ghrocketman ghrocketman is offline
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Carl,
I like that KCLO3 and Aluminum dust "ejection" charge.
Several individuals I know experimented with similar mixtures way back when I was in high school with quite entertaining results.
SHOULD still be perfectly legal to do so now with ZERO permits/licenses.

Nowadays unless you have 47 explosive licenses and permits through BATFE, CPSC, local and state fire marshals, police chiefs and sheriffs, environmental agencies and other various useless nonsense agencies, you will be charged with some sort of terrorism. My grandfather (now deceased), father, and several uncles can remember being able to go to local hardware stores to buy actual DYNAMITE for blastin' stumps, etc. without ANY sort of permit, you just had to sign for it. After that stopped, most farms I knew of used ANFO for stump removal.
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  #9  
Old 01-14-2011, 12:19 PM
WillMarchant WillMarchant is offline
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Quote:
Originally Posted by Carl@Semroc
We really want to be able to supply 10mm A1.5's to the USA team! In fact competirion is the primary reason for tooling for 10mm since it is not a "mainstream" engine.


That's an excellent idea, Carl! Any way we can help out? Preorders maybe?
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  #10  
Old 01-14-2011, 12:36 PM
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Quote:
Originally Posted by WillMarchant
That's an excellent idea, Carl! Any way we can help out? Preorders maybe?
I will let you know. For now, we are just working within our finances. December was good, so we can advance a few more steps!

We have never taken pre-orders (not with heart problems ) and I will never report to 220 stockholders again. I would not ask our friends to do anything other than what they are already doing and continue having patience with us as we expand.
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