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  #91  
Old 02-09-2019, 09:53 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, 07:11 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.
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Exemptions not regulations. Please support DOT treating slow burning solids as not subject to HMR. 2015 NAR President declines!
U.S. Rockets instaship. http://bit.ly/1aca7mA Please buy some rockets.
The O administration believed in tax, spend, borrow, fine, mandate, monologue. D voters will soon be very happy with the election outcome!
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Last edited by Jerry Irvine : 02-10-2019 at 08:10 AM.
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  #93  
Old 02-10-2019, 01:19 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, 08:35 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, 09:29 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, 09:36 PM
Les Les is offline
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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 Yesterday, 09:52 AM
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Jerry Irvine Jerry Irvine is offline
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Default Trident 2.25, 4, 12

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.
__________________
Exemptions not regulations. Please support DOT treating slow burning solids as not subject to HMR. 2015 NAR President declines!
U.S. Rockets instaship. http://bit.ly/1aca7mA Please buy some rockets.
The O administration believed in tax, spend, borrow, fine, mandate, monologue. D voters will soon be very happy with the election outcome!
Model rocketry is as safe as safe can be defined in human existence. Bow and pray: GH Stine, Orville, Vern, Lee, Lonnie, Carl, etc. No, really.

Last edited by Jerry Irvine : Yesterday at 09:21 PM.
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