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  #1  
Old 09-03-2019, 08:40 AM
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Default SRB separation Ideas for Estes Titan IIIe

Just wanted to pick some brains on some ideas of the best way to have functional SRBs on this model which is actually a clone of the original.

Iím not going to use the Estes fin setup, I will be using clear fins through the wall on the main airframe.

Also just B6 or C6-0 in the SRBís. Iíll compare burn times with the main motor to make the selection.

Two problems right up front are:

1: popping the nose cones is a problem due to the upper cargo bay being in the way.

2: hinging the SRBs is a problem because they will most likey travel into the exhaust of the main airframe engine upon release.

Iíve got some ideas but wanted to here from you all first.

The pictures are to give you a picture of the Rocket, mine isnít built yet.
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  #2  
Old 09-03-2019, 08:53 AM
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If you want to get really fancy, I saw a launch back in the mid 90's at Huntsville's Rocket City Classic where the Titan IIIe went finless without active guidance. Look up YORF member George Gassaway and see if he remembers the particulars. He was at the launch and probably knew the modeler. Other notables at the launch were Vince Hueguele, NAR trustee and Tim Pickens, who went on to build the motor for Burt Rutan's space launch, Dan Coon and Greg Warren, all were with HARA at the time. If you know any of them, they might have some details.
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Old 09-03-2019, 09:01 AM
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I popped the nosecones:

https://oldrocketforum.com/showthread.php?t=15364

The build thread is here, too.
https://oldrocketforum.com/showthread.php?t=15092

No problems with hitting the payload transition. Problems with deploying at speed with a -0 motor.
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Old 09-03-2019, 11:04 AM
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You could always go with "rear ejection" on the SRBs.
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Old 09-03-2019, 11:31 AM
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That's an interesting thought.

I built my Titian IIIe so that the boosters attached at both top and bottom. They transferred thrust to the bottom lugs and hung from the top lugs. Nosecone separation (with the breakpoint below the lugs) lifted the top off the upper lugs and let the SRB fall away.

Reversing that, so the lugs/posts point the other direction and thrust is transferred at the top and the SRB hangs from the bottom and 'noseblowing' the bulk of the SRB body tube, letting the aft body/motor pull out recovery might be a nifty solution.
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Old 09-03-2019, 06:59 PM
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Thank you Charles for your thought and link post. I actually read with great interest your post yesterday on this subject. Sure wish you hadnít suffered a Cato.

Those zero delay motors are a concern to. I thought I might get around that with extra long shock cords and wrapping the parachute in such away to delay itís opening?
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Old 09-03-2019, 07:35 PM
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Maybe. I flew it 2-3 times and didn't zipper a tube - but snapped a shockcord each time. The nosecone had enough drag by itself. I was using narrow fabric elastic bands from Walmart.

The SRBs were so light they didn't really need a chute.
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Old 09-04-2019, 02:22 PM
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Ok, I've given the problem some thought.

Here is what I'm thinking on doing. I am looking at gluing the SRB Nose Cone to 1.5" of BT60 tubing and I mean really gluing it so that it doesn't get blown off. This means cutting the SRB's main airframes which is 10.375" each at it's stock length.

Then I would glue the Nose Cone and 1.5" of BT60 to the correct location on the main air frame. This would serve as a solid anchor for the top of the SRBs. Of coarse I would use the assembled full length SRBs to improve alignment while gluing them.

The other 8.875" of the SRT's airframe will connect to the top 1.5" of tubing by BT60 Coupler. One end of the coupler will be butted against the nose cone shoulder forming a anti-blow by seal with the other 1" left over end sliding into the top of the 8.875" SRB airframes.

The bottom of the SRBs will be locked in place by 1/8" launch lugs and dowel rods, two each per boaster.

When the SRB's eject, they will slide straight downward and off the dowels. and the very small parachutes will deploy in a very natural way out of the tops of the boasters much like backfire recovery. The bottom dowels will serve as the bottom anchors during flight with most of the load being on the front 1.5" SRT upper airframe.

I'll have to be careful to have a good fiction fit on the SRB's during flight to keep them from separating at launch that is for sure.

This rocket is for small field launching only, so the SRTs will be most likely using B6-0s and the main motor would be a D12. Burn time for B6-0 is .9 seconds and the D12 is 1.7 seconds.

I added a pic of the Titan IIIe main airframe with both boosters, couplers and nose cones. I didn't add the two dowels and lugs or motor mounts.

So I now open it up to your thoughts.
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  #9  
Old 09-04-2019, 06:02 PM
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If anyone has a Rocksim File on this rocket, sure would be nice if you can post it here. It will save me a lot of time. Thank you!
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  #10  
Old 09-04-2019, 06:54 PM
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Here's my .RKT file
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