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  #91  
Old 02-09-2019, 08:53 PM
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tbzep tbzep is offline
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That's not much area. I'd hate to have to drill a hole, but I'd probably just use electronics.

However, if you want to use motor ejection, you will just about have to do some test charges and start small. You only have to do enough to kick the NC enough to pull out a loose fitting pilot chute and let it pull out the main.
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  #92  
Old 02-10-2019, 06:11 AM
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Jerry Irvine Jerry Irvine is offline
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In practice the current design works and no tubes explode. I choose not to overthink it.

But if you are going to overthink it, remember the gasses are compressible so the pressure analysis is not literal. The payload section is designed to slide off with about 10 pounds linear force and you can overthink it and back analyse the pressure at which it moves. I am guessing 20 psi or so.

So no matter the theoretical peak pressure from an oversized charge (1.2g vs 0.5g), the payload releases the pressure when the pressure rises to about 20 psi.

Overthunk.

Last edited by Jerry Irvine : 02-10-2019 at 07:10 AM.
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  #93  
Old 02-10-2019, 12:19 PM
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Yes, but you're looking at the laundry end releasing pressure, not following the volume from the source. The first restriction is where there might possibly be some damage. Going from the motor tube to the three body tubes, you have about the equivalent of a BT-5. If the charge isn't too strong and the slots have good clean glue joints/fillets, it will be ok, but I've seen Estes mini motors destroy BT-5 tubes on regular 3FNC rockets.

Build it, test it, then prep and paint it...unless you just love sanding for the sake of sanding.
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  #94  
Old 02-12-2019, 07:35 PM
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Well - Decided to try....

Using a long drill bit and files, I now have 2 ports that are 3/8" wide x 2.5" long (see pix).
Along with my concept of "PPE" - glove with masking tape to support the drill bit

The third pod I'm just going to cut the port 1/2" x 2.5". That gives me a total of 3.125. That is an equivalent of a 1.995" diameter tube.

I may decide to a expand the first 2 ports to a full 1/2", although I am concerned with wrecking things. That will grow the port area to 3.75", or the equivalent of a 2.18" diameter tube.
Of course, so long as I maintain basic structural integrity I can still do electronic deployment.

After the pods are installed I plan to perform a tethered ejection test. I will first use an adapter to install a 24mm CTI motor with its 0.6g of ejection to see if it can get the laundry out.

After that? Jump to a 38mm with 1.2g???
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  #95  
Old 02-17-2019, 08:29 PM
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I got to do some work this weekend

First, I cut the 1/2" x 2.5" slot in the third pod and motor section. Epoxied the tubes together. You can see the gap with just a 1/2" wide port vs. the 3/4" called out. I used a 1/8" dowel epoxied between the tubes to seal the gap. (need to grab a picture of it)

Started cutting ports on the tops of the pods and passenger pod. I've done them all 1/2" x 3"
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  #96  
Old 02-17-2019, 08:36 PM
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Modified the tail cone for the passenger section,

Clearance is needed for the ports. A few views attached.
Basically, the cut section clears 2 of the ports and the angled portion will be against the 3rd port (but with the angle it will allow the gasses to flow)

I plan to fill the cone with 2 part foam to reduce the volume
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  #97  
Old 02-20-2019, 08:52 AM
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Jerry Irvine Jerry Irvine is offline
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I added Tridents to the web page. It is still a work in progress.

http://v-serv.com/usr/retro.htm

I also made some changes to some Ace kit pages. Please check all links.

http://v-serv.com/usr/aceseries.htm

I also made typographical error changes to 38mm and 54mm reloadable motors, but they are not available to TRA/NAR members.

Also some changes and new kits at BMR2 series.

Last edited by Jerry Irvine : 02-20-2019 at 08:21 PM.
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  #98  
Old 02-24-2019, 06:38 PM
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Frustrated - have run into a "life situation" that is now limiting me to work on rockets barely an hour or two each weekend. But here is what I've done...

Filled the cone with 2 part foam to remove the empty volume.
Installed a T nut for a rail button.

The cone is very loose in the body tube. I decided to glue some strips inside the tube to build it up. It took 3 layers of regular copy paper. Might have been able to get a partial 4th but it was good enough for me.

The kit comes with an oversized Estes style "tea bag" style shock cord mount.
I instead drilled 2 holes in the cone and passed some kevlar through the holes for an anchor. I didn't want to trust the loop built into the nose cone....

Scored the plastic for grip, and used epoxy to glue in the cone.
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  #99  
Old 02-24-2019, 06:43 PM
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And now, to put the passenger pod on. A bit of epoxy, my foam guides, and some rubber bands...

I included a view looking into the pod and the ducts
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  #100  
Old 03-03-2019, 02:16 PM
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Cut and angled some 1/8" dowels.
Mixed up some Rocketpoxy and started reinforcing the joints and sealing the ducts!
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