Main Deployment Altitude - 500 ft or 700 ft

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GregGleason

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I hope to fly my dual-deploy Ascender, soon. I hope that it will be my first successful DD flight.

The electronics that I am using is a Perfectflite MAWD.

I keep going back in forth between the main being set to 500 ft or 700 ft.

Right now I'm leaning toward 500 ft so I can have a shorter walk. But a 700 ft will allow more time for eyes to find it.

Any thoughts?

Greg
 

Banzai88

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Start high for your first flight until you're SURE how long it takes for your parachute to deploy, inflate, and stabilize. Different methods of folding and rolling and different types of chutes all pack and unroll/inflate differently.

If it goes bad, popping lower won't save you, and could possibly be worse because you won't have any time to bleed off any velocity. If it goes bad higher up, you have more time for the slip stream to shake things loose and possibly come out with a save.

After that, choose parachute type, size and deployment altitude based on winds aloft, landing surface, and desired performance to fly the field.
 
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scsager

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First let me say - Nice Job on the AV Bay!!! :)

Either 500' or 700' should be OK. Safe recovery with no damage is the main consideration. I wouldn't go any lower than 500' on the first flight.
 

cbrarick

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then work down from there. My Wildman Jr deploys at 200 feet. No sense in walking when I can stop it a good 40 feet off the deck.
 

rharshberger

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Start high for your first flight until you're SURE how long it takes for your parachute to deploy, inflate, and stabilize. Different methods of folding and rolling and different types of chutes all pack and unroll/inflate differently.

If it goes bad, popping lower won't save you, and could possibly be worse because you won't have any time to bleed off any velocity. If it goes bad higher up, you have more time for the slip stream to shake things loose and possibly come out with a save.

After that, choose parachute type, size and deployment altitude based on winds aloft, landing surface, and desired performance to fly the field.
+1 for the stated reasons. I usually set all my DD main chutes for 500', except for the first flight which is usually 700', the method I use for packing chutes takes between 75 and 100 feet for everything to get deployed and working (based on altimeter data).
 

GregGleason

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Thanks for the comments. I see the wisdom for the 700 ft, and let me tell you why.

I just did two ground tests for the main bay (I'll do the drogue bay later, but I'm not sweating that as much). The first one was too little BP (0.7 g) and couldn't overcome the two 2-56 nylon screws. Therefore I upped the amount for 0.9 g for the second test. Things came out beautifully with full extension on the 15 foot (I think) harness. But the burrito folded chute protector never unwrapped and held the chute in place. Ugh. That's why we ground test.

The chute protector is a home-made 7"x7" square of wool fabric. These are new and haven't been flight tested enough, but I think I need to change to a different material that wants to readily separate from the chute.

So, does anyone have a better idea for a fabric to use for a chute protector?

Greg
 

rharshberger

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Thanks for the comments. I see the wisdom for the 700 ft, and let me tell you why.

I just did two ground tests for the main bay (I'll do the drogue bay later, but I'm not sweating that as much). The first one was too little BP (0.7 g) and couldn't overcome the two 2-56 nylon screws. Therefore I upped the amount for 0.9 g for the second test. Things came out beautifully with full extension on the 15 foot (I think) harness. But the burrito folded chute protector never unwrapped and held the chute in place. Ugh. That's why we ground test.

The chute protector is a home-made 7"x7" square of wool fabric. These are new and haven't been flight tested enough, but I think I need to change to a different material that wants to readily separate from the chute.

So, does anyone have a better idea for a fabric to use for a chute protector?

Greg
Nomex can be had cheap-ish from Ebay, or I have used borated ( borax and boric acid, fire retardant mix dissolved in hot water) canvas. The canvas cute protectors are not as long lasting as the nomex ones though.
 

Titan II

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Thanks for the comments. I see the wisdom for the 700 ft, and let me tell you why.

I just did two ground tests for the main bay (I'll do the drogue bay later, but I'm not sweating that as much). The first one was too little BP (0.7 g) and couldn't overcome the two 2-56 nylon screws. Therefore I upped the amount for 0.9 g for the second test. Things came out beautifully with full extension on the 15 foot (I think) harness. But the burrito folded chute protector never unwrapped and held the chute in place. Ugh. That's why we ground test.

The chute protector is a home-made 7"x7" square of wool fabric. These are new and haven't been flight tested enough, but I think I need to change to a different material that wants to readily separate from the chute.

So, does anyone have a better idea for a fabric to use for a chute protector?

Greg
https://topflightrecoveryllc.homestead.com/page3.html
 

markkoelsch

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What you need to do is attach the nomex a distance below the chute that is greater that the length of the chute. Think of it like this. It is all packed in the rocket. Charge pops and blows it out. The chute and nosecone are moving, and gets clear of the charge quickly. As it moves have the nomex pulled off and get it into clean air. Had a friend fail a L3 when the nomex never separated from his chute.

I showed him how I do it, and no problems since.
 

GregGleason

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Well, the launch is about a week away, so I wanted to test it in a day or two. I'm not sure if it would get here in time. It's an option in the future.

What you need to do is attach the nomex a distance below the chute that is greater that the length of the chute. Think of it like this. It is all packed in the rocket. Charge pops and blows it out. The chute and nosecone are moving, and gets clear of the charge quickly. As it moves have the nomex pulled off and get it into clean air. Had a friend fail a L3 when the nomex never separated from his chute.

I showed him how I do it, and no problems since.
I actually did that. But the chute protector was so toasted it retained the burrito shape and the nose cone didn't have enough energy to separate the two.

Burrito = Nomex.

If you're given to making your own, I fly this stuff, takes a blast with no issues at all: https://www.ebay.com/itm/272267182865
I may use that in the future.

I think I am going to go with a combo fabric of canvas for the outside and thin ironing board material for the inside. We will see how that works.

Greg
 

cbrarick

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so your chute protector is the problem? Use a manufactured one.
 

Nathan

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My problem with most Nomex chute protectors is that the Nomex may make them fire resistant but some are so thin that they get blast holes in them. I make my own chute protectors out of heavy cotton fabric made flame resistant by soaking in a solution of borax and boric acid. Works great. Only downside is that after washing them they need to be re-treated with the borax solution.
 

rharshberger

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My problem with most Nomex chute protectors is that the Nomex may make them fire resistant but some are so thin that they get blast holes in them. I make my own chute protectors out of heavy cotton fabric made flame resistant by soaking in a solution of borax and boric acid. Works great. Only downside is that after washing them they need to be re-treated with the borax solution.
I use the same fire retardant treatment on duck canvas (cotton canvas) from my local fabric store, while they do not last as long as my nomex protectors, they are cheap to make since a box of 20 Mule Team borax and a bottle of boric acid (powdered Roach killer). The fabric, borax and boric acid are about $20 and will make quite a few protectors, that being said a good heavy weight nomex will outlast the canvas ones by quite a bit. I think one of the key features of the fabric we use in chute protectors is it needs to be stiff, so it opens easily in the airstream.
 

GregGleason

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I use the same fire retardant treatment on duck canvas (cotton canvas) from my local fabric store, while they do not last as long as my nomex protectors, they are cheap to make since a box of 20 Mule Team borax and a bottle of boric acid (powdered Roach killer). The fabric, borax and boric acid are about $20 and will make quite a few protectors, that being said a good heavy weight nomex will outlast the canvas ones by quite a bit. I think one of the key features of the fabric we use in chute protectors is it needs to be stiff, so it opens easily in the airstream.
Yep. That's what I got, DUCK canvas. I think I'll treat mine, too.

Greg
 

Banzai88

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I use the same fire retardant treatment on duck canvas (cotton canvas) from my local fabric store, while they do not last as long as my nomex protectors, they are cheap to make since a box of 20 Mule Team borax and a bottle of boric acid (powdered Roach killer). The fabric, borax and boric acid are about $20 and will make quite a few protectors, that being said a good heavy weight nomex will outlast the canvas ones by quite a bit. I think one of the key features of the fabric we use in chute protectors is it needs to be stiff, so it opens easily in the airstream.
I actually think that the commercial nomex offerings are way too stiff, and that's part of the issue with having to get the placement and wrap just right, or they'll trap the recovery gear.

The fabric I use, posted in the link above, is not stiff or super tight weave like the commercial heavy nomex, and it works like a dream. Slip stream opens it up every time, regardless of where on the harness you place it, just get it into the airstream, so it's much more forgiving and takes the blast of the BP charge without issue.

For the $10 spent on one yard of the fabric, you can make a fleet of reusable, washable heavily fire resistant burritos. If you go the extra step and get nomex or kevlar thread, you can make them even better than commercial, and can size them specifically for your rocket. As a bonus, you can also make sleeves for your TN harnesses.

No matter what you use, the key is to make sure that you tie off the nomex far enough down the recovery harness from the nose cone that as it deploys it will pull the chute clear and you won't have to worry about whether your fabric is stiff or not, or rely on slip stream action.
 
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rharshberger

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I actually think that the commercial nomex offerings are way too stiff, and that's part of the issue with having to get the placement and wrap just right, or they'll trap the recovery gear.

The fabric I use, posted in the link above, is not stiff or super tight weave like the commercial heavy nomex, and it works like a dream. Slip stream opens it up every time, regardless of where on the harness you place it, just get it into the airstream, so it's much more forgiving and takes the blast of the BP charge without issue.

For the $10 spent on one yard of the fabric, you can make a fleet of reusable, washable heavily fire resistant burritos. If you go the extra step and get nomex or kevlar thread, you can make them even better than commercial, and can size them specifically for your rocket. As a bonus, you can also make sleeves for your TN harnesses.

No matter what you use, the key is to make sure that you tie off the nomex far enough down the recovery harness from the nose cone that as it deploys it will pull the chute clear and you won't have to worry about whether your fabric is stiff or not, or rely on slip stream action.
I use the same nomex from that seller in the Aged Copper color and it works just fine, its also ripstop iirc.
 

Bat-mite

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Some people have used lettuce and cabbage leaves .... :cyclops:

Nomex is a little better because it doesn't get as "sticky" with BP residue, but Kevlar can be used as well. GLR sells Kevlar protectors.
 

GregGleason

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My problem with most Nomex chute protectors is that the Nomex may make them fire resistant but some are so thin that they get blast holes in them. I make my own chute protectors out of heavy cotton fabric made flame resistant by soaking in a solution of borax and boric acid. Works great. Only downside is that after washing them they need to be re-treated with the borax solution.
I use the same fire retardant treatment on duck canvas (cotton canvas) from my local fabric store, while they do not last as long as my nomex protectors, they are cheap to make since a box of 20 Mule Team borax and a bottle of boric acid (powdered Roach killer). The fabric, borax and boric acid are about $20 and will make quite a few protectors, that being said a good heavy weight nomex will outlast the canvas ones by quite a bit. I think one of the key features of the fabric we use in chute protectors is it needs to be stiff, so it opens easily in the airstream.
Ok. I treated my canvas with the solution but it seems to too stiff, like it's starched.

Is there a way to get it more pliable?

Greg
 

GregGleason

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I just ball it up and flatten it, after a while it will loosen up somewhat.
Just for fun, I put a couple in the ball mill for a few hours. They are much more pliable now.

As an added bonus, a forum member is going to send me something to try!

Greg
 

AlphaHybrids

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I have been using ironing board fabric for 15 years. Just double it up and holds up well. I have one now that has 15 flights - still a troooper!

Edward
 

Handeman

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I go to the junk yard and get the used air bag material. It's hanging out of the steering wheel and dash of a lot of cars and you can usually get each old bag for a buck or so.

It doesn't last as long as the commercial nomex, but you can get a lot of them out of each air bag and they're cheap. Since they are made to contain an explosive charge, they work very well for chute protectors.

As far as deployment altitude. I've been flying my rockets for quite a while and 300 ft for the main is as high as I like to go. 200 would be better on most of mine, but I've got over a dozen flights on all of them so I would probably go with 300 or 400 ft for a new untried rocket since I pack and fold the chutes the same as I do on the older ones.
 
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