In a moment of depravity, I decided that I wanted to kitbash a combination of a Sunward Flat Foot and a Squirrel Works High 5. I am planning on using the larger diameter, but shorter BT55 from the High 5 for the Booster but use the 4 foot fins from the Flat Foot on that stage.

The Booster will use the BT50 from the Flat Foot and the fins from the High 5. I am going to look for some kind of doll head to substitute for a nose cone.

I have only built 2 staged models thus far. An Applewhite 3 Stage Cluster Cone has staged perfectly each time. It inserted a C6-0 into a D12-0 and an A10-P into the C6-0. The other attempt was an Estes CC Express wiich failed to ignite the sustainer motor from the C11-0 Booster. It was also in direct contact for all practical purposes.

As I think about this, I realize that the gap is a long one and that I have the additional complication of staging at the change of BT size. Does anyone have any suggestions as to the best way to do this?

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John A. Lee O.S.L.
Alamo Rocketeers NAR Section 661
NAR 87285, L1 8 March 2008
TRA 03040, L1 8 March 2008
Photos of the "Fleet": http://www.flickr.com/photos/23694991@N03/

I used to tell Mom, "...I want to fly rockets when I grow up!"

She said, "Make up your mind, you can't do both!"

Put some vent holes in the booster centering rings. For the interstage section, I would make something similar to the Laser-X nose cone assembly.

If you are going to use 18mm power, center a BT-50 coupler into a BT-55 coupler. Make the BT-50 coupler long enough to reach from the aft end of the BT-55 coupler to about a 3/4 to a whole inch inside of the BT-50 upper stage plus some extra length for a transition section. Have the interstage section permanently attached to the booster stage.

If you are going to use 24mm power, just make the motor mount tube long enough to reach from the aft end of the booster past the top end to incorporate a transition. Cut some vent holes in the stuffer tube and the centering rings. Then just put a BT-50 coupler into the top of the stuffer tupe.

Strongly agree with everything Intruder said. The only time you don't put the vent holes in the centering rings is when you're going minimum diameter. Run a stuffer tube up the sustainer and put vent holes in it near the top.

In gap-staging, think of the pressure your trying to relieve as water. You want it to flow out of the booster while leaving a straight shot for the burning particles from the motor to the sustainer. The pressure doesn't matter if it leaves out the back through the centering rings or the straight out the sides of the booster. However, one is a much cleaner look.

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Quando Omni Flunkus Moritati

Thanks for both the answers. They bring up more questions though...

My original intent was to stick with 18mm like in the original kits but now am wondering if I should upsize to 24mm because of the weight and drag involved. I'm leaning that way, in any event.

I'm unfamiliar with the Laser X except as an image on a facecard. I do understand that you are recommending the transition/interstage be an integral part of the booster.

I am familiar with the idea of venting. I need a pair of holes in the top of the stuffer tube. I am less clear about putting them in the centering rings. Would there even be enough room for a BT55 to BT20 let alone a BT55 to BT50? I guess I'm asking the diameter of the holes.

Something else I thought of this afternoon is that the booster will be aerodynamic. In order to avoid a core sample, I need to rig a streamer or something. Stuffing it into the stuffer tube would block sustainer ignition. It I put it in the booster BT but outside of the stuffer tube, it would not eject. I thought about stuffing it into the sustainer but am faced with not having any place to put it. Any ideas?

__________________
John A. Lee O.S.L.
Alamo Rocketeers NAR Section 661
NAR 87285, L1 8 March 2008
TRA 03040, L1 8 March 2008
Photos of the "Fleet": http://www.flickr.com/photos/23694991@N03/

I used to tell Mom, "...I want to fly rockets when I grow up!"

She said, "Make up your mind, you can't do both!"

I've cut notches in 2050 rings before as vents. It doesn't need to be much, but I've never developed a formula on size vs volume.

Here is a link to my R&D report regarding recovery ideas.
http://www-personal.umich.edu/~buzznau/Gap-StageR&D.pdf

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Quando Omni Flunkus Moritati

Well, here's a complicated approach......

The vent holes you put in the centering rings are venting the pressure to the rear of the rocket while the flaming hot material is going to the sustainer motor. You need that pressure to deploy a recovery device. I'd opt for a parachute instead of streamer.

When you assemble your stuffer tube, use a tube coupler to slip fit the motor mount portion to the section going to the sustainer. The portion going to the sustainer needs to be glued in place. If you use two centering rings for it, just make sure the ejection gases can get from your vent holes and back afte beyound the aft centering ring. The motor mount will not be glued in the rocket but slip fitted into the stuffer tube. Shock cord anchored to the aft centering ring of the stuffer tube and attached to the motor mount. The parachute attached to the motor mount between the motor mount centering rings. Parachute folded and placed between the motor mount centering rings and installed into rocket. When the pressure from the motor blows through to ignitew the sustainer, the pressure blows the motor mount and recovery system out the aft of the boost.

Wha cha thing?

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Don
NAR 53455
"Carpe Diem"

Tricky. Sounds like an R&D project for sure.

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NAR # 115523
Once upon a better day... SAM #0076
My site: http://rocketry.gonnerman.org

So your basically saying to make the booster rear ejecting. GENIUS!

If you are going to use 18mm power. I would use the same interstage method as the 24mm. However, have a 2050 centering ring in the aft end of the stuffer tube. That way the motor mount tube will fit in the stuffer tube. Also, the stuffer tube will contain most of the burning particles, which would reduce the chance of damage to the recovery system.

Thanks for the link. I downloaded a copy to peruse at leisure (when my secretery isn't looking). I appreciate it.

__________________
John A. Lee O.S.L.
Alamo Rocketeers NAR Section 661
NAR 87285, L1 8 March 2008
TRA 03040, L1 8 March 2008
Photos of the "Fleet": http://www.flickr.com/photos/23694991@N03/

I used to tell Mom, "...I want to fly rockets when I grow up!"

She said, "Make up your mind, you can't do both!"

I think it sounds intriguing. It also sound like something I am sure to mess up. That makes it more intriguing. I think I follow what you're saying but do you have any sketches?

Thanks for the input.

__________________
John A. Lee O.S.L.
Alamo Rocketeers NAR Section 661
NAR 87285, L1 8 March 2008
TRA 03040, L1 8 March 2008
Photos of the "Fleet": http://www.flickr.com/photos/23694991@N03/

I used to tell Mom, "...I want to fly rockets when I grow up!"

She said, "Make up your mind, you can't do both!"