Making a rocket wadding-free: baffle or nomex?

Discussion on ground control/GSE and recovery equipment. This includes launch pads, triggers, chutes, streamers etc. Includes other items such as simulation and other computer software, etc.

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Making a rocket wadding-free: baffle or nomex?

Postby Raaahbin » Wed Dec 28, 2011 1:49 pm

Hi folks,

Hoping I can learn from others' experience on this one: I am going to be building a couple of rockets soon, and am interested to try out a wadding-free setup. I have always used standard wadding or dog barf in the past, so I don't have any experience in other forms of recovery protection. I'm a bit of the way through building an Aerotech Initiator, which has a baffle in it, but I'm deciding between ordering baffles or nomex chute protectors for some other rockets (BT55-BT70 sizes). Does anyone have recommendations as to which would be better? And why? Or are there very much "horses for courses"... if so, which horses for which courses?

Thanks,
Robin

ETA: If I go with the nomex option, do I also need a shock cord protector?
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Re: Making a rocket wadding-free: baffle or nomex?

Postby Scoop1261 » Wed Dec 28, 2011 1:58 pm

Personally, I would go with the Nomex option, and yes you would also need shockcord protectors or a short Kevlar leader.
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Re: Making a rocket wadding-free: baffle or nomex?

Postby PK » Wed Dec 28, 2011 2:08 pm

Piston.

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Re: Making a rocket wadding-free: baffle or nomex?

Postby Scoop1261 » Wed Dec 28, 2011 2:10 pm

PK wrote:Piston.


Even better

I guess it is a bit "Horses for Courses" but my reasoning of Nomex over baffles, is that the nomex is easily replaced when worn and could even be used in multiple rockets, where the baffles are a little less maintainable, however as PK has suggested a piston could be the ultimate solution.
Last edited by Scoop1261 on Wed Dec 28, 2011 2:22 pm, edited 1 time in total.
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Re: Making a rocket wadding-free: baffle or nomex?

Postby PK » Wed Dec 28, 2011 2:19 pm

Troy once did (and I think still does) a really nice baffle setup in a 38mm rocket consisting of a stainless steel scourning pad secured by two, perforated, bulkheads.
To my mind, a piston is less work but his solution was elegant and certainly allowed him to turn those little rockets around super fast.
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Re: Making a rocket wadding-free: baffle or nomex?

Postby OverTheTop » Wed Dec 28, 2011 2:54 pm

I vote for the stainless steel scourer too. Although it is a case of horses for courses as said before.

I have tried the scourers, baffles, dog-barf and streamers (flame resistant, used as wadding) from Spotlight. All work well.
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Re: Making a rocket wadding-free: baffle or nomex?

Postby Raaahbin » Thu Dec 29, 2011 9:49 pm

Thanks for all your feedback - that's been most helpful!

I have one other question about the nomex protectors: are they too heavy for low power rockets? I was just looking at the Sunward Aerospace site, which proudly states that its nomex protectors weigh "only" 6.5 ounces... but that's the better part of 200g, which seems like a lot of weight to add to a rocket compared with traditional wadding. Should I save such things for MPR/HPR?
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Re: Making a rocket wadding-free: baffle or nomex?

Postby guy97 » Thu Dec 29, 2011 11:48 pm

I think thats the thickness not the actual weight. It think its 6.5 ounce is the density either per sq metre or per sq yard maybe. I have a 4*4inch sheet here it it fews a few grams
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Re: Making a rocket wadding-free: baffle or nomex?

Postby Lamp » Fri Dec 30, 2011 12:10 am

For LPR I still use Wadding or "Dog Barf", but there is nothing wrong with Nomex (I use it in all my MPR and HPR). Guy is right, it does not weigh that much, I agree with him that the quoted figures are probably 6.5 Ozs per square yard (or square metre).
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Re: Making a rocket wadding-free: baffle or nomex?

Postby Wingnut » Fri Dec 30, 2011 12:22 am

My 2 cents...

I've had great results using pistons and baffles in LPR's. I've made my own pistons for a number of rockets from BT-5 up to BT-60. For rockets made from BT-70 and BT-80 I've simply bought a FlisKits baffle kit from Suburban Rocketry. Use Kevlar shock cord and you won't need a separate shock cord protector.

In my larger rockets, my personal preference is a Nomex chute protector but I still use some dog barf to protect the Nomex from the full force of the ejection charge.

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Re: Making a rocket wadding-free: baffle or nomex?

Postby Kryten » Fri Dec 30, 2011 9:38 am

Just in case you haven't considered:
With a piston or Nomex chute protector you need to use Kevlar in the "exposed" section of shock cord.
A baffle with scourer means you can use virtually any shock cord
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Re: Making a rocket wadding-free: baffle or nomex?

Postby rocket_troy » Fri Dec 30, 2011 10:38 am

Kryten wrote:Just in case you haven't considered:
With a piston or Nomex chute protector you need to use Kevlar in the "exposed" section of shock cord.
A baffle with scourer means you can use virtually any shock cord

That's the actual reason for me heading in the baffle direction back then. Of course, now I take a far more sensible approach and do away with the hot stuff altogether :P

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Re: Making a rocket wadding-free: baffle or nomex?

Postby jez_tranter » Tue Feb 12, 2013 9:26 pm

I have used a kitchen fire blanket as a cheap alternative to nomex. Quite successful but you still have to protect the shock cord.

You can get a 1 m x 1 m fire blanket from bunnings for $10.

It is made of fibreglass and a bit messy when you cut it as it frays - but you can hem it if you are keen or just replace it from the remaining 0.99 m2 you have left over.


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