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  #1  
Old 02-14-2021, 04:09 PM
shockwaveriderz shockwaveriderz is offline
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Smile Making your own thin-mill mylar parachutes: parachute duration

Has anybody ever successfully glued 2 pieces of silver mylar parachute material together to make a bigger chute and had it stay together during deployment?

research indicates to me that contact cement( roll or spray) might work. Heat sealing ?

I found this:

"it is possible to glue together multiple sheets to form a large sheet. To do this, use the type of contact cement that is used for styrofoam. It does not melt mylar and it dries quickly without the remaining exposed bits of cement still remaining tacky."

to which contact cement are they referring to?

UHU POR ? Weldwood?



TIA
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  #2  
Old 02-14-2021, 08:34 PM
olDave olDave is offline
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Default just how big do you need to make your chute?

mylar already comes in bed-sheet-sized pieces (go get a space blanket)

some observations
---bigger chutes require big BT sizes to contain them (more drag)
---bigger chutes are harder to protect from hot ejection gas
---bigger chutes add more mass to your rocket and tend to reduce maximum altitude
---bigger chutes take more time to open fully (while your duration rocket freefalls)
---bigger chutes get tangled up more frequently (and sometimes don't open at all )
---bigger chutes can more easily get caught in a thermal and leave the county, which is not good if you are competing under rules that require you to return the rocket to the judges

the point is, there are some trade-offs to consider.
the reason I point out this stuff is that many moons ago, I tried using super-sized chutes made from dry cleaner bags for duration competition.
ask me how I learned these lessons.
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Old 02-14-2021, 08:41 PM
olDave olDave is offline
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Default also--

the more thin your chute material is, the more prone it is to tearing or stretching....and melting when you try to join it to another piece

it would be well worth your time to do some testing (with heavy suspended loads) to see where the minimum thickness is

sorry but I can't give you any suggestions on availability of thin MIL mylars, I have not competed in this area for decades
maybe someone can post suggestions where to find good-quality (good strength) mylar these days
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Old 02-17-2021, 10:52 AM
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Ez2cDave Ez2cDave is offline
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Default

Quote:
Originally Posted by olDave
mylar already comes in bed-sheet-sized pieces (go get a space blanket)

some observations
---bigger chutes require big BT sizes to contain them (more drag)
---bigger chutes are harder to protect from hot ejection gas
---bigger chutes add more mass to your rocket and tend to reduce maximum altitude
---bigger chutes take more time to open fully (while your duration rocket freefalls)
---bigger chutes get tangled up more frequently (and sometimes don't open at all )
---bigger chutes can more easily get caught in a thermal and leave the county, which is not good if you are competing under rules that require you to return the rocket to the judges

the point is, there are some trade-offs to consider.
the reason I point out this stuff is that many moons ago, I tried using super-sized chutes made from dry cleaner bags for duration competition.
ask me how I learned these lessons.


I am pretty sure that Shockie is talking about 1/4 mil Aluminized Mylar, for "all-out" competition chutes, not the mylar "survival blankets".

Dave F.
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  #5  
Old 02-18-2021, 10:45 AM
ASP ASP is offline
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Default

Aerospace Speciality Products has 1/4 mil Mylar available in 54" square sheets.
https://www.asp-rocketry.com/ecomme...e.cfm?cat_id=42
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  #6  
Old 02-19-2021, 07:32 AM
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Default

I think the UHU would work. Would it hold ? Only testing would tell.
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Old 02-19-2021, 01:09 PM
shockwaveriderz shockwaveriderz is offline
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Quote:
Originally Posted by barone
I think the UHU would work. Would it hold ? Only testing would tell.


that's what I am going to do. see if I can literally rip them apart after I glue them together.
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Old 02-19-2021, 01:51 PM
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Quote:
Originally Posted by shockwaveriderz
that's what I am going to do. see if I can literally rip them apart after I glue them together.


Another thing to consider is how "fold-able" the seams are when packing the parachute.

Does it dry rigid ? Does it tend to "stay folded", once it is folded?

Etc, etc, etc .

Dave F.
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  #9  
Old 02-19-2021, 06:48 PM
shockwaveriderz shockwaveriderz is offline
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Quote:
Originally Posted by Ez2cDave
Another thing to consider is how "fold-able" the seams are when packing the parachute.

Does it dry rigid ? Does it tend to "stay folded", once it is folded?

Etc, etc, etc .

Dave F.


Those are questions I hope to answer. Besides glue I'm also going to try to "heat-seal" them.....

I'm going to try several different glues and seam widths......and various double sided tapes....

There's a CA adhesive double sided tape that's available but it may be too thick for my purposes....

I can't believe that nobody has every done any tests like this before. I've got almost every possible R&D report available via the NAR but there doesn't seem to be any research done in this area before. If anybody knows of any, drop me a line.
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Old 02-19-2021, 11:12 PM
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Quote:
Originally Posted by shockwaveriderz
Those are questions I hope to answer. Besides glue I'm also going to try to "heat-seal" them.....

I'm going to try several different glues and seam widths......and various double sided tapes....

There's a CA adhesive double sided tape that's available but it may be too thick for my purposes....

I can't believe that nobody has every done any tests like this before. I've got almost every possible R&D report available via the NAR but there doesn't seem to be any research done in this area before. If anybody knows of any, drop me a line.

Hmmmm.....sounds like an R&D report in your future.....
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