Any special considerations for jam-packed payload tube?

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Hmm, they couldn't do a 7.5 bag in like 6in? I am ordering my DBag this week. I may just do the 7.5x10 because the rocketman 16' chute feels like it's going to pack bigger than a normal chute. Have an inquiry out to Fruity Chutes at the moment.

I sent Gene the dimensions and material of my chute, and he recommended the bag I got. As it is, my chute just barely fits in there.

Moving the bulkhead seems like the way to go. I think I may still have the internal bulkhead that came with it. I had to order the external separately. I can figure this out, but I'd like to see your pics, too.
 
Measurements on MadCow's site are wrong. Payload tube is 24". Coupler is more like 16", I can't remember for sure. Add in the U-bolts and charge wells sitting on top of the coupler, and I come up with about 8" of free space. And I have a 10" D-bag! Plus 30' tubuklar Kevlar harness, plus 36" chute protector. :facepalm:
The payload section is 26in long. You have 8in of coupler from each direction which leaves about 10in. Once you add the bulkheads charge cups, etc. in I can see why there is only 7in of space. It's why I put my nosecone bulkhead 2 in from the top side of the NC coupler so I could gain another 12in of space.
I think you are misunderstanding my point:

* Take everything out of the payload bay
* install coupler as for flight
* measure inside from the coupler bulkhead to the opposite end of the payload bay
* that is the length of tube you need to pressurize

It doesn't matter how much stuff you have in the tube - it will all move and leave a void behind. So you have to figure the total empty space from the bulkhead until the bottom of the d-bag or whatever leaves the payload bay. Unless your kit is different that what's shown on the Mac Cow Rocketry website, the coupler is 12" long and the A/V bay is 26" long. That leaves 20" of open tube to pressurize. Add in the 850lbf to shear the 5 pins.

How much stuff you have in the payload bay does not change how long the open tube is.


Tony
 
This is the same methodology I use.
I went back and re-read your post (#4) and that is exactly what I do as well. Hasn't failed me yet. How full the payload bay is does not matter, if anything, may need need more oomph if everything is a tight friction fit.

I would be concerned about the amount of force required to shear those five 8-32 screws. All told the OP is going to need about 1000 lbs of force to get things out the door. That sure seems like a lot. Is there a reason you picked that amount of force?


Tony
 
I went back and re-read your post (#4) and that is exactly what I do as well. Hasn't failed me yet. How full the payload bay is does not matter, if anything, may need need more oomph if everything is a tight friction fit.

I would be concerned about the amount of force required to shear those five 8-32 screws. All told the OP is going to need about 1000 lbs of force to get things out the door. That sure seems like a lot. Is there a reason you picked that amount of force?


Tony

I'm sure I went overboard, but I was concerned about losing the nose at apogee.
 
I'm sure I went overboard, but I was concerned about losing the nose at apogee.

For reference, I am using (3) 4-40 screws but unlike your flight all my laundry deploys through the nose so I want them to break at apogee. I just need the screws to hold back the pressure differential.
 
For reference, I am using (3) 4-40 screws but unlike your flight all my laundry deploys through the nose so I want them to break at apogee. I just need the screws to hold back the pressure differential.

How about those pics of your NC coupler? :wink:
 
I'm sure I went overboard, but I was concerned about losing the nose at apogee.
At BALLS a few years ago I found I needed more nose weight than I thought for a big rocket I was flying, an N to well over 10,000' in a 6" rocket. But I had calculated the shear pins on the original weight so at the top it popped out the main when the shock cord hit the end.

It took 600 seconds to come down. I swear it thermaled upwards several times. It seemed to take forever to come down and I was lucky the winds were light. So I understand the caution in keeping the laundry in until it's supposed to come out.


Tony
 
I bought a new bulkhead (Madcow got it to me from CA in two days!) and I have decided to put my tracker in the AV bay and just epoxy the bulkhead into the NC coupler. I'll recess it three or four inches. That should be quick, a minimum of changes to the design, and easy to install.

I should have my thrust plate by the end of the week, and ready to ground test by 3/18. That gives me three potential Saturdays for testing prior to LDRS.

Whew.
 
I bought a new bulkhead (Madcow got it to me from CA in two days!) and I have decided to put my tracker in the AV bay and just epoxy the bulkhead into the NC coupler. I'll recess it three or four inches. That should be quick, a minimum of changes to the design, and easy to install.

I should have my thrust plate by the end of the week, and ready to ground test by 3/18. That gives me three potential Saturdays for testing prior to LDRS.

Whew.


Sorry, I haven't gotten up to the rocket shop yet to take pictures. Your plan sounds good though. Hearty fillet on each side and you should be good.
 
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