First Bluetube 2.0 scratch build with DD

Hello TRF!

I'm attempting to build my first HPR Bluetube 2.0 with DD. I would love for any suggestions and or tips. I am using the new Aerotech DMS L1000W as the motor. My goal with this build is to do the following:

1) Break 2 miles

2) Reach Mach of slightly above

3) Have a great time


I do have a few questions:

1) Would it be worth using 1/4 inch centering rings to hold the MMT into place or should just go full minimum diameter?

2) Does anyone know how long the nose cones are for the Always Ready Rocketry? It doesn't specify on their site.

View attachment BT2_Rocket.ork

Sounds like fun. I'm not sure which nose cones ARR is supplying, but I suspect they are equivalent to LOC.
I've had great success with Blue Tube - you'll like it.

I love Blue Tube and use it in a lot of my builds. One thing to keep in mind, the final build is usually quite a bit heavier than the simulation. Make sure that every component you can think of is in the design file. Check out my rocksim file for my L2 Basic Blues 3", I put in everything I could think of and was still a good 20% off final build weight. https://www.rocketreviews.com/always-ready-rocketry-always-ready-rocketry---basic-blues.html

Taking a quick look at your design, I personally would reduce it to a 3 fin, and play with fin shape and size until I got to a stability cal of around 2.

Killachrome said:

2) Reach Mach of slightly above

Click to expand...

There's a lot of turbulence at the Mach transition, so it's best to stay under Mach or go past it. Your fins are slightly swept-back, which increases the chance of flutter.

In general, optimizing for altitude and speed simultaneously is impossible. Drag is proportional to the square of the velocity so going faster generally means not going higher. Also, for speed you'll want the minimum mass, while for altitude the optimal mass will generally be higher.

Killachrome said:

1) Would it be worth using 1/4 inch centering rings to hold the MMT into place or should just go full minimum diameter?

Click to expand...

If you mean should should you reduce the body diameter rather than use centering rings in a larger body, then probably yes. Drag is based largely on the frontal surface of the rocket (S = πr²), so reducing this will allow you to fly faster/higher. However, you want to make sure you have enough space for the recovery system and it looks to me like you have too small a main parachute bay for a minimum diameter rocket.

Thanks everyone for the help and advice! I have spent most of the day playing around with the design, but I do have a slight problem. No matter what I change or weight I add, I am still having trouble getting my apogee time to 18 seconds which is the max delay for the L1000. The easiest solution would be to used a plugged motor, but I am wanting to use the L1000 due to budget constraints. Any help would be most appreciated!

Killachrome said:

No matter what I change or weight I add, I am still having trouble getting my apogee time to 18 seconds which is the max delay for the L1000.

Click to expand...

You're using dual deployment, so why do you care about motor ejection? Just plug the motor and let the electronics fire at true apogee (not what you guess/sim it to be).

I was going to use it as a backup, but I will take it out and get some more distance. Since I have only used Cessaroni motors, would I use the Aerotech 54mm forward plugged closure or would I use a piece of thin cardboard and CA glue? I have never plugged a motor before and I tried searching both on the forum and google with no luck. Thanks

PS. John, please do more videos because they are very helpful!

On a CTI, you would pop the paper cap off the ejection charge, scrape out ALL the Black Powder, then fill the space up with dog barf, and use masking tape to seal.
Aerotech, roughly the same, empty the BP out (or dont put it in) fill space with dogbarf, and cap.