jcato
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It sure does! Nice job - and thanks for sharing its 'birth' with the TRF community! I'm sure there are many who will benefit from the knowledge you shared.
-- john.
Build Thread - 9 ft, 24 Gore, Semi-Elliptical Chute
- Thread starter Handeman
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It sure does! Nice job - and thanks for sharing its 'birth' with the TRF community! I'm sure there are many who will benefit from the knowledge you shared.
-- john.
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Beautiful!
Nice chute! Figured it would be a good kite flying day.
Who was flying the that black triangle UFO in the last photo?LOL
Elaine took the pics and was hiding behind my Durango to stay out of the wind. That UFO was the back hatch.
grouch
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So jealous! Very nice work from start to finish.
rfjustin
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Awesome job and good luck with L3!
JimJarvis50
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Great job on the chute! Green and gold next time??
How are you planning to do the deployment (i.e., bag, pilot, etc.)?
Jim
How are you planning to do the deployment (i.e., bag, pilot, etc.)?
Jim
grouch
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Jim, connections to Baylor by chance or just good taste?
Green and Gold is the Green Bay Packers, everyone knows that!
I considered Green and Gold. My RC controlled chute is Green and Gold, as are most of the smaller home made ones. I have a 4" Thug, since retired, in a Packers theme. I plan to do a 3X up scale of that. 12" OD and 99" tall. That will be Packers Backer III and definitely have a Green and Gold chute!
As for the deployment, I did some ground testing at my TAPs house this week. He has loaned me his d-bag to use for my flight. The bag will be attached to the forward av-bay along with the shock cord. The bag will only extend out of the upper tube a couple of inches. This will allow the bag to protect the chute, but the nose cone will pull everything out. That is the method he has used on his L3 rockets for over 10 years, so that's what I'm going with.
I may explore d-bags and pilot chutes further on later flights.
JimJarvis50
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The latter (or maybe not so much).
Interesting deployment method. You just need to make sure your drogue is sized correctly and it should work fine. I trust your harness will be longer than your shroud lines? I've actually seen it not that way, and the ending wasn't good.
Jim
That harness and chute size will be checked and rechecked! That seems like a pretty simple thing to make sure of, but it's always the simple things we forget that seem to doom a flight!
P.S. Great headgear!
Wow, wow, and wow!! I was wondering if a stiff wire might be used to slide through the seam, crimp the paracord and and pull through in one swoop? Might be easier than trying to work the large needle through? Kurt
You might be able to do that, but I'm not sure it will save you much time or be much easier. Of course you have to have a long enough piece of stiff wire. In this case you would have needed at least a 6 ft piece. I actually thought threading the lines through was one of the easier steps in building this. There was only one end where I had some difficulty getting the line past the seams at the top end of the gore. For a little bit, I thought I might have to split the seams and resew them a little further apart. I had made the tunnel part too narrow, but once I got the folded part of the cord with the needle through, the rest was easy.
So I made a drogue chute using the same techniques I used to make this chute. They will be a matching pair.
I didn't do a "build" on the drogue, but I posted some pics in the build thread for my L3. The drogue pics are in posts 55 & 57.
I made a Disk-Gap-Band chute for the drogue. It is the same design as the one used to drop the Viking lander on Mars. Of course that chute was 53 ft in diameter, mine is 2 ft. One thing about the Disk-Gap-Band is that its Cd is only 0.52 instead of the 0.75 that most chutes have.
I didn't do a "build" on the drogue, but I posted some pics in the build thread for my L3. The drogue pics are in posts 55 & 57.
I made a Disk-Gap-Band chute for the drogue. It is the same design as the one used to drop the Viking lander on Mars. Of course that chute was 53 ft in diameter, mine is 2 ft. One thing about the Disk-Gap-Band is that its Cd is only 0.52 instead of the 0.75 that most chutes have.
JonathanOtt
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I've been playing with ChuteCalc and have a question.
How do you print the gores actual size?
The spreadsheet has a note on it that says (something to the effect of) "...the pattern can be enlarged as needed."
So how do you enlarge it?
Print one off, measure it and then do the math to figure out how much to enlarge by, then tell your printer to print X,000% of actual size?
Or do you go into page view, and stretch the plot until you get the X & Y dimensions right, then print?
I guess it could be done either way, but there has to be an easier way.
The Scott Bryce gore generator converts to an actual size PDF, but that is a hemispherical 'chute, where Nakka's is semi eliptical.
Is it six of one, half-dozen of the other (or is that another discussion for another time)?
Jon
How do you print the gores actual size?
The spreadsheet has a note on it that says (something to the effect of) "...the pattern can be enlarged as needed."
So how do you enlarge it?
Print one off, measure it and then do the math to figure out how much to enlarge by, then tell your printer to print X,000% of actual size?
Or do you go into page view, and stretch the plot until you get the X & Y dimensions right, then print?
I guess it could be done either way, but there has to be an easier way.
The Scott Bryce gore generator converts to an actual size PDF, but that is a hemispherical 'chute, where Nakka's is semi eliptical.
Is it six of one, half-dozen of the other (or is that another discussion for another time)?
Jon
I didn't print it at all. The pattern was on a grid and the output said what centimeter size the grid pattern was. In this case, a 2cm x 2cm grid pattern. In less than the time it would have taken to figure out how to print it full size and then put all the pages together right, I just drew half of it. I had a roll of brown builder paper for rolling tubes and folded a length of that in half and laid out the 2cm squares and drew half the pattern on it using the fold as the center-line of the gore. Having a yard-stick with centimeters on it, or a "meter-stick" makes laying out the grid pattern pretty painless, tedious but painless. I then added seam allowances all the way around and cut out the paper pattern. I then traced the unfolded pattern onto an 1/8" thick piece of Tempered Hardboard Panel and cut that out and sanded the edges smooth.
The hardboard pattern works much better for cutting the gores with a hot knife than a paper pattern, especially for larger sizes and multiple gores. It gives you a solid edge to follow with the hot knife and the melted nylon edge sticks to the edge of the hardboard. This is a good thing since I had to move the pattern and nylon to complete the cutout since it was slightly longer than the 3' x 5' cement board I was using as a cutting surface for the hot knife. The cut nylon stuck to the pattern and made it easy to move and adjust to complete the cuts without having to make sure it was still positioned on the nylon right. It pulls loose from the pattern very easily when you are done.
I still have some of the hardboard left although I've made more patterns from it. I usually use hardboard patterns for any chute above 36" diameter or more than 8 gores. I use the builders paper because it works well when rolling tubes for smoke grains in my ex motors, but you could use any type of paper for laying out the grid patterns.
JonathanOtt
Well-Known Member
This is one that needs to be put in an encyclopedia of how to do things. I'd have never found it if it wasn't for someone mentioning it.
I appreciate the though and hope you got some good info from this thread. There were a lot of things I learned and still use with my chutes today, but this chute is kind like my scratch built, 2" ID mailing tube, 38mm MMT, DD, L1 cert rocket. It worked fine, and flew great for many years, but I would never build one like that again.
If I were to build this chute again, I would never thread the shroud lines across the top of the canopy like I did on this one. This chute will probably hold up to a very high speed (hundreds of MPH) deployment, but we really don't have those types of deployments in our rocketry. After building this, I had a long talk with my brother, a licensed parachute rigger (should have done that first). He said with the relatively slow deployment speeds our rockets use, all I needed was to zig-zag stitch about 5" - 6" of the shroud lines to the gore seams. That would have made it pack so much smaller.
Just a note, The only chutes I built after this one was the drogue and pilot chute for that rocket. I've found that most of my L1 and L2 rockets, up to about 12 lbs. work just fine on various size umbrellas. From 28" kids to 53" golf umbrellas. I use 150 lb. Dacron (3/32" OD) for shrouds and zig-zag about 1 1/2" of the shroud line at each gore seam. They don't look all that nice, but cost me <$1 each (I collect trashed umbrellas when I need a chute) and the only one that failed did so when the ejection went off at motor burnout, (about 280 MPH). The failure was the umbrella seams, not the shroud line attachment points. It still worked as a pretty good streamer and the only damage to the rocket was the zipper from the high speed deployment.
I do plan to build a few chutes for the new rockets I have in by build queue, but that's a little in the future.
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