New Design -- Blackjack

[CPMcGraw]

This one looks like a model I will just have to try building. The performance is great, with excellent Dv numbers. What will be the most complex will be the drilling out of five 1/4" holes through a pair of BC-1045 cones...

If only there was a laser drill... :D

Length: 40.50"
Diameter: 1.04" (ST-10)
Fin Span: 5.85" (Jay's upscale Chuter-II fins)
Weight: 2.12 oz


B6-4......331'......Dv 8 FPS......36" x 1/8" rod
C6-5......817'......Dv 7 FPS......36" x 1/8" rod


The A8-3 is not recommended at all. The B4-4 is acceptable in a pinch, but reaches 10' lower altitude, and has a higher Dv number.

Enjoy!

[JRThro]

I like it a lot, Craig.

At first I thought it was just larger forward and aft sections joined by a thinner midsection. That in itself would make me like it, and I probably won't even attempt to build it with the 5 (!!!) smaller gas ducting tubes between the forward and aft sections. Maybe I'll modify it with a single small tube to duct the gases.

Since I don't have Rocksim, I opened the .rkt file in OpenRocket 1.1.0, and it told me it was ignoring the spill hole in the parachute (did you use one?). However, it also shows five 1/4" tubes overlaid on one another at the model's centerline between the forward and aft sections, and it doesn't show a motor mount at all. So I added a motor mount, thrust block, centering rings, and motor clip (mass object). I haven't looked into the parts in much detail, so I don't know what else it might have missed or screwed up.

Using a C6-5, max. altitude in OpenRocket 1.1.0 was ~575 ft.

[CPMcGraw]

I like it a lot, Craig.

At first I thought it was just larger forward and aft sections joined by a thinner midsection. That in itself would make me like it, and I probably won't even attempt to build it with the 5 (!!!) smaller gas ducting tubes between the forward and aft sections. Maybe I'll modify it with a single small tube to duct the gases.

Since I don't have Rocksim, I opened the .rkt file in OpenRocket 1.1.0, and it told me it was ignoring the spill hole in the parachute (did you use one?). However, it also shows five 1/4" tubes overlaid on one another at the model's centerline between the forward and aft sections, and it doesn't show a motor mount at all. So I added a motor mount, thrust block, centering rings, and motor clip (mass object). I haven't looked into the parts in much detail, so I don't know what else it might have missed or screwed up.

Using a C6-5, max. altitude in OpenRocket 1.1.0 was ~575 ft.

OpenRocket probably doesn't know how to work with Subassemblies. The engine mount is a subassembly using a 4" ST-7. The lower 1" extends out the rear and has 8 small 'cooling vanes' attached. These are cut from 0.020" (or 0.025") matteboard. My general idea is to have them laser-cut.

The parachutes (yes, two of them) do not have spill holes. They are simply basic Semroc 12" parachutes built per the instructions.

Thanks for the heads-up on the new version of OpenRocket. I'll DL it and see how it compares. (Addendum below.)

As for the five small tubes, they're essentially very long launch lugs (LL-3) and not standard tubes. If you can locate some heavier-walled tubes with an OD of 0.25", I'd suggest using them instead.

I now have OpenRocket downloaded. The five Gas Passage tubes can be manually set by editing each one. The "Radial Distance" is 0.30", and the angles are 0, 72, 144, 216, and 288. This will clear up the visual aspect.

I'll finish up the file and save it in OpenRocket format.

[Doug Sams]

As for the five small tubes, they're essentially very long launch lugs (LL-3) and not standard tubes. If you can locate some heavier-walled tubes with an OD of 0.25", I'd suggest using them instead.FYI, Totally Tubular (http://www.wooshrocketry.org/misc/tt.htm) lists such a tube: T-2, 0.246" od, 0.013" wall thk. Not sure if anybody else carries it or not.

Doug

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[CPMcGraw]

Here's the OpenRocket file version I mentioned. There was a need to revise the file to take care of some glaring omissions.

The performance numbers are conservative, compared to RockSim.


B6-4......229'
C6-5......510'


OpenRocket does not yet have user-chosen preferences for the simulation data displays.

The file is zipped, since the ORK format is not recognized yet here on YORF...

[CPMcGraw]

FYI, Totally Tubular (http://www.wooshrocketry.org/misc/tt.htm) lists such a tube: T-2, 0.246" od, 0.013" wall thk. Not sure if anybody else carries it or not.

Doug

.

That's another set of component data we need to include in the CSV files... :o

Thanks, Doug!