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Wadding for H motor lauch?

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tildenm

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Hi all,
Noob to high power stuff. I am looking to get my Level 1 this weekend(!) and have the rocket ready to go (sans motor which I found will be available at the launch). The only thing I am missing is wadding. Will regular low-power wadding work? Do you think someone will have some spare Nomex or some for sale?
Tilden
 

troj

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I wouldn't trust regular paper wadding -- HPR ejection charges will blow right through it, unless you use a gob.

If a vendor will be on site at the launch, see if they sell heat shields -- that's the best route.

Otherwise, get yourself a bale of cellulose insulation from the local home improvement store for $8 and you'll have a lifetime supply!

-Kevin
 

RocketMonkey

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I wouldn't trust regular paper wadding -- HPR ejection charges will blow right through it, unless you use a gob.

If a vendor will be on site at the launch, see if they sell heat shields -- that's the best route.

Otherwise, get yourself a bale of cellulose insulation from the local home improvement store for $8 and you'll have a lifetime supply!

-Kevin
+1
luts of dogbarf or Nomex
 

Handeman

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That's my recommendation too. Go with the dog barf (cellulose insulation) I got my bale on sale when they had damaged bales in clear plastic bags for $2.98 each. Should have gotten two, but as it's been said, one is a lifetime supply.
The nomex shields are OK, I've got four I use, but they do get holes if they are too close to the charge, and that means the chute gets a few holes too.
 

Pantherjon

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Most of the time if you fly with a club they will have the 'dog barf' there available for fliers..No need to buy any- unless you want to..I bought a bale 2 years ago, filled a huge plastic tote and I have barely put a dent in it!:eek:
 

tildenm

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Haha, dog barf it is! That will be easy enough.

Wish me luck, hopefully will be Level 1 when y'all see me again!!!
 

MarkII

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I have a Kevlar heat shield from Giant Leap and a Nomex shield from Top Flight. Neither one has seen action yet. :( (Yikes, the GLR shield is almost 4 years old!) GLR says that their Kevlar shields are much more burn-resistant than the Nomex kind, and to be honest, their shield does seem to be a bit thicker and to have a denser weave than the Nomex one from TFR. But aramid fiber is aramid fiber, regardless of whether it is called Kevlar or Nomex, right? Does anyone have any experience with GLR's Kevlar heat shields who can say whether or not there is any basis for the claim that they hold up better than the Nomex variety?

MarkII
 

troj

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GLR says that their Kevlar shields are much more burn-resistant than the Nomex kind, and to be honest, their shield does seem to be a bit thicker and to have a denser weave than the Nomex one from TFR. ... Does anyone have any experience with GLR's Kevlar heat shields who can say whether or not there is any basis for the claim that they hold up better than the Nomex variety?
Giant Leap's statement is an accurate one.

In addition to the burning from the charges, there's also a ballistic factor, as well, and Kevlar is much better against the ballistic aspect. It's more a function of the type of fiber than it is the thickness.

I have some plain Nomex heat shields, and I have a variety of sizes of Kevlar ones. The Kevlar holds up better; the Nomex ones, especially with HPR ejection charges, tend to develop holes in them.

The Kevlar shields, on the other hand, have had charges laid directly underneath them and have black marks to show for it, but that's it.

-Kevin
 

Fade_to_Black

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Giant Leap's statement is an accurate one.

In addition to the burning from the charges, there's also a ballistic factor, as well, and Kevlar is much better against the ballistic aspect. It's more a function of the type of fiber than it is the thickness.

I have some plain Nomex heat shields, and I have a variety of sizes of Kevlar ones. The Kevlar holds up better; the Nomex ones, especially with HPR ejection charges, tend to develop holes in them.

The Kevlar shields, on the other hand, have had charges laid directly underneath them and have black marks to show for it, but that's it.

-Kevin
Ditto that. I just picked up 50 sq feet of kevlar off ebay to make shields for my L3 project for dirt cheap. I held a lighter under a piece to see what would happen, direct flame just darkened it a little. In my ground testing, the main shield was hit with a 5 gram charge with a little dog barf between it and the charge and all it got was some sooty black marks. All my nomex shields have holes in them. Kevlar for me from now on.
 

redsox15

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What are peoples views on a baffle section instead of the dog barf or kevlar. I am in the process of building a rocket capable of an H motor and also had questions on parachute protection. I have 1/4 in plywood in my basement that I was thinking about using to make a baffle kit of sorts to separate the charge from the parachute. To protect the wood from the embers I was going to glaze the pieces in epoxy.

Matt
 

als57

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Guess I haven't had any issues with the TFR nomex shields yet. Have a couple that have 25+ flights on them with no burn throughs. The one GL kevlar is in my HiTech 45 and has 30+ flights on it with no issues.


Al
 

ttabbal

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What are peoples views on a baffle section instead of the dog barf or kevlar. I am in the process of building a rocket capable of an H motor and also had questions on parachute protection. I have 1/4 in plywood in my basement that I was thinking about using to make a baffle kit of sorts to separate the charge from the parachute. To protect the wood from the embers I was going to glaze the pieces in epoxy.

Matt

If you have room, that works reasonably well. Personally, unless you get fancy with the baffle, I would still put some dogbarf in. Some HP fliers don't like baffles as they limit the length of the motor you can install in the rocket. I am undecided, but as I usually use dual deploy on HP flights, the issue doesn't often come up for me.
 

n5wd

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What are peoples views on a baffle section instead of the dog barf or kevlar. I am in the process of building a rocket capable of an H motor and also had questions on parachute protection. I have 1/4 in plywood in my basement that I was thinking about using to make a baffle kit of sorts to separate the charge from the parachute. To protect the wood from the embers I was going to glaze the pieces in epoxy.
Baffles work quite well - that's what I'm converting all of my 3" and larger rockets to use. Besides the obvious advantage of not needing wadding or dog barf, you can also build your rocket with a zipperless design, preventing a tear in the airframe caused by a line or tether cutting into the airframe at high speed. If you do get a zipper, it'll be on the upper airframe where it'll be easier to repair than on a booster section.

Here's a couple of pix showing my 3" TARC-task booster and the construction details of the boosters I use.

DSC_4892.jpg


DSC_4254.jpg
 

BsSmith

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I've used a Nomex heat shield on my Titan with no problems at all. Over 2 :)o) launches there has not been even a dark spot on the two 58" chutes, I like that.

My Talon came with Kevlar protectors and they seem to be nice, much stiffer then the Nomex one, they almost seem too stiff to seal the sides of the tube. I may need to find a way to give them a better "seal" before I use them, or use some dog barf with them for the first few launches and let the heat do it for me.
 

BayouRat

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I've blown holes in both Nomex and Kevlar shields. But I am overly aggressive with my charges since I started using sheer pins. On my aggressive charges I use dog barf and a Kevlar shield. Seems to work every time.

Note: For a small rocket (2.6" or less). Estes paper wadding can be used. Just make sure you only use half or less of the charge supplied with the motor. (No more the .65 grams) .65 grams is what is in an Estes D12
 

Conan4480

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I have a rocket that I use a Nomex heat shield in. Two flights with no problems. I also have a additional centering ring towards the forward section of the rocket to crate a chute chamber. This not only prevents the chute from sliding down the body tube but it puts the chute farther away from the ejection charge.
 

tildenm

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Whats Up Hobbies was out at the ROC launch today and hooked me up with a Nomex pad (I had a roll of insulation in the car, but pretty purchases are hard to resist!). Anyway, pleased to report I am a L1 now! Actually a 1.5 as I took the test for the L2 while there (why not!?)...
Tilden
 
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Fade_to_Black

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(I had a roll of insulation in the car, but pretty purchases are hard to resist!).
Tilden

Are you talking about the pink fiberglass insulation? If so, that's pretty much considered a no-no as it's not biodegradable, and if you're flying close to a farm, livestock may ingest it. Use the blown-in cellulose insulation instead. If that's what you're using, disregard this post. ;)
 

tildenm

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Are you talking about the pink fiberglass insulation? If so, that's pretty much considered a no-no as it's not biodegradable, and if you're flying close to a farm, livestock may ingest it. Use the blown-in cellulose insulation instead. If that's what you're using, disregard this post. ;)
Actually that is what I did have and I thought it seemed strange to use this. Good catch, fortunately didn't use at the launch and (now) won't use at all. Anyone need a roll of attack insulation? :)
 

MarkII

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Thanks, Kevin and Fred. That is pretty much what I thought. I have seen many references in the forums to using Nomex heat shields, but I couldn't recall seeing anyone talk about using a Kevlar one. It seemed that something like half said that the Nomex protected the chutes well with no problems, while the other half reported getting pinhole-sized burn holes in their shields (and in their chutes). That's why I asked.

MarkII
 

Handeman

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Thanks, Kevin and Fred. That is pretty much what I thought. I have seen many references in the forums to using Nomex heat shields, but I couldn't recall seeing anyone talk about using a Kevlar one. It seemed that something like half said that the Nomex protected the chutes well with no problems, while the other half reported getting pinhole-sized burn holes in their shields (and in their chutes). That's why I asked.

MarkII
I'm not sure you should limit it to pin-hole sized. I have some dime sized holes in some of my shields.
 

kramer714

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Congrats on level 1, what rocket were you flying at the ROC launch? I was flying the I500 saucer.

I use dog barf plus nomex. On some of my rockets I make a 'poor mans piston' out of nomex with dog barf in it, Then I tie the end with a cable tie, looks like a limp boxing glove. I have even attached the ejection charge wire to the cable tie to make sure it stays put. The charge sits between the piston and the bulkhead, with the parachte on the other side of the piston. Helps keep things from moving from one side of the parachute bay to the other plus makes a spongy piston that slides out well. If I remember to do it, I have the 'piston' end near the end of the tube as a zipper stopper. Works well! I have done this with a nomex shield over the shock cord and without.

One warning, do ground test it, the 'pillow' effect seems to dampen out some of the uuumph of the charge, you might need a bit extra.
 

tildenm

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Congrats on level 1, what rocket were you flying at the ROC launch? I was flying the I500 saucer.

I use dog barf plus nomex. On some of my rockets I make a 'poor mans piston' out of nomex with dog barf in it, Then I tie the end with a cable tie, looks like a limp boxing glove. I have even attached the ejection charge wire to the cable tie to make sure it stays put. The charge sits between the piston and the bulkhead, with the parachte on the other side of the piston. Helps keep things from moving from one side of the parachute bay to the other plus makes a spongy piston that slides out well. If I remember to do it, I have the 'piston' end near the end of the tube as a zipper stopper. Works well! I have done this with a nomex shield over the shock cord and without.

One warning, do ground test it, the 'pillow' effect seems to dampen out some of the uuumph of the charge, you might need a bit extra.
Saw yours! It was great!

Ine was the large florescent orange rocket. Looking forward to next months, I am going to do my L2 cert flight on a AARAM kit from PML.
 
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