CC Express Engine Conversion

[juno]

Hi

I am recently returned to what was a consuming hobby for me as a child. I have been spending quite a lot of time reading through many of the posts on this site and have not been able to find an answer easily.

I recently completed building a CC Express and have found that C11-0 engines are no longer available. I do not want to lose the rocket on D engines and was wondering if there is a way to easily convert the rocket to use 18mm engnes, like a C6-0 and and a B engine in the sustainer.

Unfortunately it is already painted and it may be difficult to remove the existing engine mounts.

Any help would be appreciated, or if anyone knows of a source with left over C11-0 engines, that would also help.

In the future, I will seek out multi-stagers that use 18mm engines....

Thank you for any suggestions, and especially for this wonderful resource. I feel as though I am 12 again, only now I can pretty much buy any rocket I want!

[wyldbill]

The problem you may run into here is that a C6-0 doesn't have nearly the average impulse of a C11-0. I'd sim this to make sure you can get a safe launch. Make sure the factor in the weight of the adapters.

That said, you could take a used 24mm casing and make an 18/24mm adapter. Clear out the nozzle (or cut down an E casing), and add a engine block (the 18mm may stick out a bit). Friction fit the C6-0 in the adapter and the adapter in the lower stage. Do the same for the upper. You could also actually make an 18/24 adapter w/ tubes and rings. This would be lighter and a bit safer.

FWIW,
-bill

[kurtschachner]

You might check local shops in your area since they weren't big movers off the shelf. There are still some around here I think.

[CPMcGraw]

...I recently completed building a CC Express and have found that C11-0 engines are no longer available. I do not want to lose the rocket on D engines and was wondering if there is a way to easily convert the rocket to use 18mm engnes, like a C6-0 and and a B engine in the sustainer...

Juno,

This rocket does need a "hotter" boost than you normally get from an 18mm C6-0 booster, but you can still safely reach over 1000' using the C6-0 in this rocket if you build a couple of 18mm-to-24mm adapters. More important, you will also need a 48" x 3/16" launch rod. The standard 36" x 1/8" rod is both too short and too flexible for this model. Get a one-piece steel rod from Lowes or Home Depot.

Here are some simulation runs to gnaw on:

C6-0 / C6-5......1500'......Dv 22 FPS......42"
C6-0 / B6-6......1070'......Dv 24 FPS......39"

The last measurement in these lines represents how far up the rod the model reaches before it gets to safe flight velocity.

Dv means "Deployment Velocity", BTW. This is how fast the rocket is moving when it tosses the laundry at the top. These numbers are a tad high, so you will also need to "reef the chute" to prevent an explosive opening of the canopy. This is just a short piece of launch lug (about 1/4" long) that forces the canopy to open at a slower rate than normal. It slides over the shroud lines up to the skirt of the canopy, and as the canopy opens, it drags the lines against the inside of the lug, regulating the speed of opening.

[CPMcGraw]

I just ran the simulation again with a D12-0 / B6-6 combination, and got a much better result:

D12-0 / B6-6......1475'......Dv 9 FPS......33"

The D12 has the "hotter" boost needed to get the model moving. Also note the Dv is much lower, meaning you don't need to reef the chute to keep it from shredding. And, the model can launch from a 36" x 3/16" "Maxi Rod" instead of that 48" x 3/16" rod. Finally, note the altitude is only 25 feet lower than the C6-0 / C6-5 combination. This would be the ideal pair of motors.

You're not going to get a safer lower altitude with B6-0 boosters; you might not even get off the rod.

[juno]

Thanks for all the help!

[ghrocketman]

More reasons why we need the C5-0 and B14-0 back !
Staged but relatively LOW altitude flights !