I was very excited to see that the original Double Duty worked so well and is quite a sight to see with the booster parachute recovery. The only problem was that it is small to see and the color white make it even harder to see in a overcast, white, sky.

Here is my first go at a SLS design with the SLS Double Duty. If built, a few parts are custom such as the CR-9125 and HTC that I used for the first stage is the JT-70E cut to 1 inch long, hoping the it will fit the LT-225 with a little extra glue. Also it will be required to cut a 3 inch section, for the booster stage, off of the LT-225140 and the ST-930 will be cut to 2.25 inches for staging fit.

PS. This is my "best guess" on the heavy duty parts for the SLS design so any input would be appreciated.

Enjoy and Thanks Again, JP.

James Pierson
NAR# 77907
.

Attached Thumbnails

     

Attached Files

SLS Double Duty.rkt (97.3 KB, 120 views)

I seperated the the rocket into a two stage design.
Gained 100 ft in max alt.
Bob

Attached Files

SLS Double Duty_fix.rkt (78.1 KB, 88 views)

The BTH-70 is 2.247" OD and 2.175" ID. We also use it as an HTC-225 coupler. We can cut it to any length.

__________________
Carl McLawhorn
NAR#4717 L2
semroc.com

James,

Before you get too sky-happy, take a look at the launch guide length...

Using Blindeye2's revision, the guide length is 47". Even with a 48" rod, you have to subtract about 3" to allow for the blast deflector, and another 10" for the launch lug position on the tube. That only gives you 35" of guide length.

You also need a V12 in place of that twin-rotor Wankel booster...

__________________
Craig McGraw

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SAM 0044
AMA 352635

When I went back and looked, the original simulation has both engines firing
at launch with a max acceleration of 681 ft/sec/sec. The revised 2 stage version
has a max acceleration of 452 ft/sec/sec. What was an ok launch rod length
of 32 in became 46 in. Good eye for the details McGraw.
Bob

I am always " Sky Happy " Craig, especially at test flight time .

To fix the LL problem I could add an lower LL at the bottom of the 2nd stage and use a 48" rod, should have done that anyways for the SLS design. Good catch. Also have notice with the Fixed file from Bob that the Dv's are a little higher and may need to make some design/ fin adjustments.

Thanks for the input Craig, JP.

James Pierson
NAR# 77907

The 2 stage version I uplaoded displays the booster altitude in the plot
of the flight simulation. With an ESTES D12-0 booster engine, the booster
stage peak altitude is about 340 ft. I have wondered why no stageing data
is available in the summary of flight simulation results. You can select booster
data to be plotted. It would be nice to get the staging time, altitude, and velocity
at staging, and the booster peak altitude in the simulation summary.

Bob

Thanks for the info Carl. I will update the file using the BTH-70 as a HTC of 1 inch long. Also I could not find the CR-9125 listed at Semroc. I know you can custom cut most anything but I prefer using in stock/listed parts.

Just wondering if I missed the listing for the CR-9125 and are they paper(.05?) or lite ply of what thickness?

Thanks all at Semroc, JP.

James Pierson
NAR# 77907

They are there now. I thought I had them listed. They are .050 fiber. Plywood would be thin, but possible.

__________________
Carl McLawhorn
NAR#4717 L2
semroc.com

Thanks Bob, I always make things more complicated than what they really are. I set the MM tubes as 1st and 2nd stages seperately. My mistake and thanks for the fix. With your file in the 2D flight mode I can see the booster image drop away. Very cool!!

What will tell me in Rocksim at what altitude the booster drops away?

Thanks for the help, JP.

James Pierson
NAR# 77907