#21
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Early or late production on the Cherokee-D? A late production semi-clone that I built back in 1994 drifted out of sight after a successful flight on an Estes E15-8. However, an Estes E motor of any description will require some nose weight. I am surprised that you did not simulate the old Estes Omega with an E12-0/E12-8 combo. If you really want to fly heavy models on black powder motors, I think that you would need a core or semi-core burning motor.
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'Til next time, Mike Toelle NAR 31692 L1 SAM 0373 |
#22
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Counter-intuitive but true. Jerry |
#23
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First simulations with a Cherokee DD...
Simulation 1: E12-0/E12-8......2709'......Dv 16 FPS......60" x 1/4" (45" required) Simulation 2: D12-0/E12-8......2225'......Dv 8 FPS.......60" x 1/4" (47" required) Simulation 3: E12-0/D12-7......2126'......Dv 31 FPS......60" x 1/4" (43" required) I figured a lighter design would work better, and these first runs tend to confirm it. It was a pleasant surprise to see a D12-0 doing as well as it did as the booster, and to see a 500' difference in altitude between it and the E12-0. One item to note with these simulations, all three include a 3 oz allowance for a BoosterVision camera and 9V battery.
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Craig McGraw BARCLONE Rocketry -- http://barclone.rocketshoppe.com BARCLONE Blogsite -- http://barclone.wordpress.com BARCLONE Forum -- BARCLONE Forum BARs helping BARs SAM 0044 AMA 352635 |
#24
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Using a standard Cherokee, I ran simulations with both 18" and 16.4" tubes:
Short-body: E12-6, 2018', Dv 29 FPS, requires 0.375 oz of ballast at base of NC, has a margin of 1.43. 28" of rod. Long-body: E12-6, 1987', Dv 25 FPS, requires 0.25 oz of ballast at base of NC, has a margin of 1.45. 29" of rod. The E12 requires ballast on both versions. The margin was below 1.0 for both without it.
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Craig McGraw BARCLONE Rocketry -- http://barclone.rocketshoppe.com BARCLONE Blogsite -- http://barclone.wordpress.com BARCLONE Forum -- BARCLONE Forum BARs helping BARs SAM 0044 AMA 352635 |
#25
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Not entirely correct. Your forgetting the NAR safety code rule 7 Size. My model rocket will not weigh more than 1,500 grams (53 ounces) at liftoff and will not contain more than 125 grams (4.4 ounces) of propellant or 320 N-sec (71.9 pound-seconds) of total impulse. 3 E9 are 35.8 * 3 = 107.4 grams OK 4 E9 are 35.8 * 4 = 143.2 grams NOT OK - HP and you need a L1 |
#26
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I don't quite follow this... The D12 burn duration is 2.7 seconds, is it not?? The E9 is 3 seconds, correct?? So the E12 is now 2.5 seconds, with the same peak thrust as a D12?? How is this a higher performing motor (IOW an "E" motor) if it has the same DURATION as a D12 and the same peak and average thrust as D12?? I get it that it's a LOW END "E" motor, so it's not going to be double the duration of a D12 at the D12's average and peak thrust levels to be a "full E", or that it has DOUBLE the peak and average thrust for the same duration as a D12, (or some combination thereof) but I don't follow how this is an "E" motor if it has the same burn characteristics as a D12... and the D12 at 17N/s isn't a FULL "D" motor either... I must be missing something... Last I heard though, thrust times duration = total impulse (motor letter class) later! OL JR
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The X-87B Cruise Basselope-- THE Ultimate Weapon in the arsenal of Homeland Security and only $52 million per round! |
#27
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Yep, you're missing something. The D12 is 1.6 seconds. The E12 burns 50% longer.
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Roy nar12605 |
#28
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The thrust curve is similar to the D12, except it burns for another second.
Remove the ".txt" from the file "Estes.E12.eng.txt" and you will have a working .eng file. Greg Quote:
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#29
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My first thought! I actually have an upscale Centuri Stiletto that I made to launch from a D12-0 to an E9-8. Rocksim put it up at around 2900 feet. I have to make another booster now to hold the E12-0 booster. Looks like I will finally have my first rocket capable of breaking 3000 feet! It will be interesting to see if the sustainer will gain more altitude with an E9-8 or an E12-8.
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"AND I hope they are from the planet of the "Chunk spunky Mary-Lou Retton clones". - Ironnerd "Those who trade liberty for security have neither" - Benjamin Franklin "Semroc is almost always the answer" - Stefanj www.paulsavia.com www.soundclick.com/paulsavia |
#30
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BTW, I wasn't clairvoyant - I didn't anticipate the advent of a longer booster motor. I only made the booster longer, as I recall, to keep it closer to scale. But it oughta work perfectly with the E12-0. Doug .
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