Advice About Disposable Wadding Alternatives in LPRs

[prfesser]

MSDS for #11208 - CREPE PAPER (dick-blick.com)

SECTION 1 – PRODUCT AND COMPANY INFORMATION (greenfiber.com)

Well, both contain fire retardant, though the crepe paper doesn't specify which fire retardant ("Components of construction: Cellulose, Dye, Fixative, Flame Retardant, Ink (printed streamers)"). Borax/borate buffer solution is the cheapest and certainly the least-toxic retardant, and is used in paper-production adhesives as well, so at a SWAG I'd guess that's what the crepe paper contains. As to the dyes, fixatives, etc., I don't have any idea as to what's used.

Many/most types of paper go through very similar manufacturing processes. I'm not saying that dog barf is any better than crepe paper, but based on the MSDS for crepe paper, it appears that it's no worse, at least from a hazardous-chemical standpoint.

Best -- Terry

 

[mh9162013]

"Yes, I'm serious.
I'll tell you what. Go take a $5 and rip it up and throw it away. But before you complain, remind yourself that it's only $5 and nothing to be bothered about"

I don't mean to be contentious here but you just spent ~$3.96 per motor, (I dont fly much LPR, but a 3-Pack of C6-5 is $11.90 on Amazon) and which are used only once. Assuming you fly the entire package, that is <2x the $5.00 you mentioned. (HPR gets a just a tiny, little-bit, not worth mentioning really.... more expensive!) And one is litterally lighting those $$ on fire!

Envronmentally, BP motors generate combsution gasses, and I am sure those can't be somehtning you'd want to breathe? (Althouigh I am a non-smoker so I dont get that whole concept in the first place!) and lets not even talk about AP motors, which are available in 18mm... (I am a EE, not a Chem E, so I am not an expert on the properties of the smoke/compbustion gasses, but they cant be as healthe as fresh. clean mountain air !)

So while I understand, and don't disagree with your "Leave No Trace" flying, Dog Barf & Wadding are biodegrable and prehaps not such a concern?

Oh and by the way, I have a few rockets that use baffles with the Stainless "scrubber", an HP as well, and I am always surprised that they work as well as they do!
They add weight of course, so in LPR, maybe not useful, but MPR and up, they may be an option. (I still use a blakent though)

Anyway Happy flying!

Right now, I'm paying about $2 per motor (I currently fly 13mm minis). But here's the thing, there's no alternative to using these. Even if there was, one has to wonder how much cheaper that alternative would be. And for the record, cost is the the primary reason I'm currently avoiding MPR.

As for the ill health effect from the smoke and combustion byproducts, I'd like to avoid that, too. But again, what's the alternative? If there is one, I'd consider it.

I'm also open to the idea of getting rid of ejection charges altogether. But I'm not aware of any deployment product that works with LPRs and provides the ability to eject a parachute at minimal apogee altitudes, like 75 feet. This is what I estimate my Alpha III gets when using a 1/2A3-2T engine (this Alpha has been modified to use 13mm engines and has a screw on retainer).

Anyways, if there's something out there that's the size of a Jolly Logic AltimeterTwo that can sense apogee and deploy the recovery system at that moment (or at a later time that's programmable) is something I'd be strongly interested in it. But I don't think it exists, b/c the rocket itself would need some sort of power to eject the nose cone or w/e to expose the packed parachute to the atmosphere. But maybe something like a Jolly Logic chute release would work, if it could be modified to work at lower altitudes and be made smaller. Then it would attach to some "contraption" in the nose cone that is held to the rocket body with a spring under tension at the time of launch. Then during release, that spring pops off the nose cone to release the parachute.

Another problem with what I want is that I'd be limited in my BP motor selection. I suppose I could buy a regular Estes BP motor, then remove the ejection charge. But wouldn't that violate a law or NAR code or something?

 

[Back_at_it]

The issue you're going to run into is with the BT20 tube size. It is far too small for a fire blanket to be used. Even 3x3 is way to large.

Since you don't want to use anything non-recoverable your option is a baffle. I've been using baffles for years with great success. There are really only a couple of things you need to keep in mind when using the baffles.

- The baffle needs to be far enough forward that it does not upset the CG of the rocket. In small BT20 rockets this normally means that it needs to be at or above the half way point of the rocket.

- The baffle needs to have enough flow as to not restrict the ejection and cause too much pressure. Too much pressure could cause other issues like splitting the body tube or ejecting the motor out the back.

In the rare occasion that I put a baffle in BT20 I use the plate style with at least 3 plates (4 if the rocket is long enough). Each plate is cut a little larger than a 1/2 moon and the plates are positioned such that they overlap slightly so there is no direct path for burning embers to hit the recovery gear.


EDIT: One more thing to add. As for Dog Barf (insulation). A 50 SQ Ft. bag is about $15 in my area right now and a bundle typically lasts me two to three seasons. Keep in mind that a large number of my rockets have baffles in them or use fire blankets if they are large enough (BT80 and up) so most flights do not use it. It's not a lifetime supply but it does go a long way.

 

[Pem Tech]

Dog barf works well and we have a bucket for everyone to use at every launch. As a solo LPR flyer it may take you a while to make a significant dent in a bale of blow in attic insulation, but it works well and is environmentally safe. It does produce "litter", but one rain and the stuff dissolves. Plus it comes out in such small pieces that no one really notices it on the ground.

Look for a damaged package at a home improvement store and make them an offer.

What he said.

 

[mh9162013]

The issue you're going to run into is with the BT20 tube size. It is far too small for a fire blanket to be used. Even 3x3 is way to large.

Since you don't want to use anything non-recoverable your option is a baffle. I've been using baffles for years with great success. There are really only a couple of things you need to keep in mind when using the baffles.

- The baffle needs to be far enough forward that it does not upset the CG of the rocket. In small BT20 rockets this normally means that it needs to be at or above the half way point of the rocket.

- The baffle needs to have enough flow as to not restrict the ejection and cause too much pressure. Too much pressure could cause other issues like splitting the body tube or ejecting the motor out the back.

In the rare occasion that I put a baffle in BT20 I use the plate style with at least 3 plates (4 if the rocket is long enough). Each plate is cut a little larger than a 1/2 moon and the plates are positioned such that they overlap slightly so there is no direct path for burning embers to hit the recovery gear.

Yeah, I figured a reusable parachute protector would be too big for a BT-20 rocket. Right now, my current design will use a BT-50 tube. If I have the space, I'll use both a 3x3 protector and the baffle. But space is a consideration with the baffle. Then there's the potential issue with upsetting the CG of the rocket, which I didn't think about, but I'm glad you brought that to my attention.

Here's a question for you. Let's say you're putting a baffle into a BT-20 or BT-50 rocket and you have 2 options.

Option 1: Using a 3-plate half-moon style baffle that's 1.5 inches long and it's 1.5 inches away from the top of the motor.

Option 2: Using a 4-plate half-moon style baffle that's 2.0 inches long, but it's 1 inch away from the top of the motor.

Assume the stability and size of the rocket are comparable with either option.

Which option do you use? I imagine option 1 has the benefit of maybe lasting a little bit longer since it's further away from the ejection charge. But option 2 has the benefit of doing a better job protecting the parachute.

 

[waltr]

I have used the 3 half moon plate design in BT20, 50 & 55 tubes with great success. About 1.5" from end of MMT is good.
Also use the center spline for shock cord attachment which makes the cord replaceable.

 

[prfesser]

The issue you're going to run into is with the BT20 tube size. It is far too small for a fire blanket to be used. Even 3x3 is way to large.

Doug Pratt used to sell a very simple, low-cost BT20 rocket, aimed for bulk buy. Plastic vacuum-formed (I think) nose cone, streamer cut from caution tape, kevlar shock cord, and a square of nomex, thin and about 3x3", as a streamer protector. It worked pretty well for the Upward Bound kids for whom I taught a rocket class.

Best -- Terry

 

[Lee Haltom]

I'm not a fan of dog barf either @mh9162013

Use a crepe paper streamer with a penny tape to it. You roll the streamer really tight so it's a slip fit into the body tube. Put the streamer in, set the penny on top and then shove it down the tube so it's sets right above the motor, then pack the chute in.

The streamer falls to earth after apogee, and you pick it up and reuse it. It also helps in tracking the direction of the rocket.

It won't work with an Estes tri-fold style shock chord mount that is near the nose cone though, you need to use a motor retained shock chord mount, or bury the Estes style mount down deep into the body tube.

You can get the crepe paper streamer @ Walmart and it's flame resistant. I'd suggest testing it's flame resistance.

View attachment 516723 View attachment 516724 View attachment 516725 View attachment 516726View attachment 516727View attachment 516728View attachment 516729

When I use dog barf it winds up getting in my mouth somehow. Maybe it’s the brand I bought at Lowes but I don’t like it as much as I thought I would.

 

[mh9162013]

Also use the center spline for shock cord attachment which makes the cord replaceable.

How does that work exactly? If you tied a Kelvar cord to that point, it's probably a few inches deep into the main body tube, right? So how do you untie the knot and reattach a new Kevlar cord?

 

[Back_at_it]

Yeah, I figured a reusable parachute protector would be too big for a BT-20 rocket. Right now, my current design will use a BT-50 tube. If I have the space, I'll use both a 3x3 protector and the baffle. But space is a consideration with the baffle. Then there's the potential issue with upsetting the CG of the rocket, which I didn't think about, but I'm glad you brought that to my attention.

Here's a question for you. Let's say you're putting a baffle into a BT-20 or BT-50 rocket and you have 2 options.

Option 1: Using a 3-plate half-moon style baffle that's 1.5 inches long and it's 1.5 inches away from the top of the motor.

Option 2: Using a 4-plate half-moon style baffle that's 2.0 inches long, but it's 1 inch away from the top of the motor.

Assume the stability and size of the rocket are comparable with either option.

Which option do you use? I imagine option 1 has the benefit of maybe lasting a little bit longer since it's further away from the ejection charge. But option 2 has the benefit of doing a better job protecting the parachute.

I would go with option 2. The 4 plate design will protect the recovery gear better. Once you have assembled your baffle, coat the wood with thinned wood glue. The wood glue will help to protect the baffle even if it's only 1 inch from the end of the motor.

For reference. I have a Baby Bertha with 24mm mount in it. That rocket uses a 4 plate baffle with the plates spaced approx. 1/2" apart. The bottom plate is about 7/8" of a inch from the top of the motor tube. According to my flight log, that rocket has 11 flights on it without any issues.

In both of you options you need to account for CG.

 

[Hyak]

"When I use dog barf it winds up getting in my mouth somehow. Maybe it’s the brand I bought at Lowes but I don’t like it as much as I thought I would. "

No, No, No! You cant eat it raw, you have to put Cholula Hot Sauce on it! Then it tastes great! Fire Roasted with some sandy bits thrown in.... Mmmmmm

So back on topic, 13mm are pretty small, so you'd have to use bigger motors i'd imagine to use systems like JL Chute release. [DISCALIMER: I have never tried siming anything with a 13mm motor with a rocket that would fit electronics so maybe it would work, but Mass? Mass? Mass?]

If you dont already have it, get OpenRocket which is free, and will allow you to sim these sorts of ideas

 

[waltr]

How does that work exactly? If you tied a Kelvar cord to that point, it's probably a few inches deep into the main body tube, right? So how do you untie the knot and reattach a new Kevlar cord?

I do the cord as a loop just long enough to exit the top of the BT. Easy to just cut. A longer cord is tied to this loop.
To get a new piece in, I tie a small weight (hex nut) to the cord, dangle into the baffle, tilt the BT to get the weight around the spline and turn BT to get it to fall out of the baffle and BT. Easy.

 

[Kelly]

I don't care what anyone uses, but if you think you will save money by using nomex you most likely won't. A nomex wrap will cost at least as much as a bale of dog barf, possibly much more. And nomex doesn't last forever, it is subject to wear and tear and heat/fire damage. You will be replacing your blanket before you run out of dog barf.

 

[DigBaddy]

I don't care what anyone uses, but if you think you will save money by using nomex you most likely won't. A nomex wrap will cost at least as much as a bale of dog barf, possibly much more. And nomex doesn't last forever, it is subject to wear and tear and heat/fire damage. You will be replacing your blanket before you run out of dog barf.

And one 3" nomex blanket is usable in only small rockets. Build something bigger, you need another blanket. Lose your rocket, you lose the nomex as well. I've rigged mine up to be quickly swapped between larger rockets to save on costs a bit, but a scratch and dent bale of barf for BT60 and smaller is sure cheaper than buying a nomex blanket for each rocket and faster than swapping blankets between rockets. Ensure a gallon ziploc bag is full and in the range box before each outing and we're good to go.

If one thinks a bale of insulation is excess, find an under-insulated spot in the attic and use some there; may pay for itself over time

 

[mh9162013]

I do the cord as a loop just long enough to exit the top of the BT. Easy to just cut. A longer cord is tied to this loop.
To get a new piece in, I tie a small weight (hex nut) to the cord, dangle into the baffle, tilt the BT to get the weight around the spline and turn BT to get it to fall out of the baffle and BT. Easy.

Oh, ok, that makes sense.

One of hesitations I've had to using a baffle is where to attach the shock cord, as I like to avoid the Estes teabag mount near the top of the main body tube. Attaching it to the baffle makes sense, but I didn't know how you could replace the cord. But if it's a loop that goes around somerthing, I can see how it's easy to replace.

Thanks!

 

[mh9162013]

I don't care what anyone uses, but if you think you will save money by using nomex you most likely won't. A nomex wrap will cost at least as much as a bale of dog barf, possibly much more. And nomex doesn't last forever, it is subject to wear and tear and heat/fire damage. You will be replacing your blanket before you run out of dog barf.

I'm using the reusable wadding in a BT-50 rocket (maybe BT-60 eventually), so the largest peice I'm going to use is 6x6 inches or so. I think I can get one for about $7.

What's your best guess as to how long a 3x3 or 6x6 piece of reusable wadding will last? 50 launches? 300 launches?

 

[MidOH]

I've been running long, full length tubes on all of my low power scratch builds. I use two couplers. Three moon baffles in the lower coupler, just one in the upper. Glue my shock cord into the upper coupler after that baffle.

Then I use a small scrap of blue jeans tied to the shock cord for wadding. Loose. The baffles do most of the work. You can spray fire retardant on just about anything. My arc flash clothes are just plain clothes, retreated. Heck, if your rocket is fiberglass, dampen the jean scrap with anyrhing.

I only burrito dual deployment chutes. Half burrito, top exposed for low power. 2/3 to Full burrito for medium power. For single deployment, the nomex or whatever, is just used as reusable wadding. Chute sits naked above it, and above the shock cord.


LOLz at bt20 rockets. Oh no, my caution tape streamer has melted spots! Hahhaa. Just toss some cabbage in there. Has nobody considered using wadding paper AS the streamer? That crepe party paper makes a perfect streamer.

 

[RokitFlyr]

If someone is that concerned about the cost of flying supplies, I'd say pick another hobby.....
Just my $.02...

 

[mh9162013]

If someone is that concerned about the cost of flying supplies, I'd say pick another hobby.....
Just my $.02...

It's not about the cost of supplies. It's about wasting supplies.

 

[Tractionengines]

I'll only say 1 word.... PISTONS.

 

[mh9162013]

I'll only say 1 word.... PISTONS.

I'm listening...

 

[lakeroadster]

Well, both contain fire retardant, though the crepe paper doesn't specify which fire retardant ("Components of construction: Cellulose, Dye, Fixative, Flame Retardant, Ink (printed streamers)"). Borax/borate buffer solution is the cheapest and certainly the least-toxic retardant, and is used in paper-production adhesives as well, so at a SWAG I'd guess that's what the crepe paper contains. As to the dyes, fixatives, etc., I don't have any idea as to what's used.

Many/most types of paper go through very similar manufacturing processes. I'm not saying that dog barf is any better than crepe paper, but based on the MSDS for crepe paper, it appears that it's no worse, at least from a hazardous-chemical standpoint.

Best -- Terry

No worse? I'm always amazed how folks can read a document, yet miss the statements made in that document that are specifically applicable to the topic at hand.

Per the above referenced documents

Cellulose​

Hazard Overview: ... Care should be taken to minimize the amount of this product released to the environment to avoid ecological effects.​

Crepe Paper​

Hazard Classification This product is classified as not hazardous in accordance with the Globally Harmonized System of Classification and Labelling (GHS)​

 

[mikec]

The ones I'm interested in are from Dino Chutes and they are not made out of Nomex...at least not completely.

They used to use Nomex but I don't think there is any Nomex in their flame-retardant fabric. If it's brightly colored it almost certainly isn't Nomex. Can't speak for Dino but I've had pretty bad luck with orange-colored protectors from another major vendor -- after 5-6 flights the things are full of holes. YMMV. I like dog barf for LPR.

 

[bjphoenix]

I use dog barf, but I find it to be a PITA. One, it's messy and gets all over the place if you are prepping at home. Second, it isn't the easiest to pack - too little and you get embers pushing through, too much packed too tight, you can get a failed deployment

Somebody gave our club a bale so they brought it to the last launch along with a bunch of gallon zip lock bags and gave everybody a bag. I tried it for 3 launches and had 2 failures.

One of the club members has a big plastic jar, probably bigger than a gallon, full of the stuff and labeled on the outside in wide tip marker "dog barf". I was thinking what would someone say if they saw that container setting in their garage?

How does that work exactly? If you tied a Kelvar cord to that point, it's probably a few inches deep into the main body tube, right? So how do you untie the knot and reattach a new Kevlar cord?

All of my rockets have a short kevlar cord attached, the LPR have a small diameter metal loop on each cord. Then I have separate 6' and 10' kevlar cords with snap swivels, attach one snap to the leader on the rocket and attach the other one to the nose cone. My chutes also have snap swivels but frequently these days I use streamers and my crepe paper streamer has a string tied to it with a loop. I run the shock cord through the loop before attaching to the nose cone and it's captured. For larger tubes my chute protector also has a string on it with a loop so I run the shock cord through that loop and it's captured too.

 

[prfesser]

No worse? I'm always amazed how folks can read a document, yet miss the statements made in that document that are specifically applicable to the topic at hand.

Per the above referenced documents

Cellulose​

Hazard Overview: ... Care should be taken to minimize the amount of this product released to the environment to avoid ecological effects.​

Crepe Paper​

Hazard Classification This product is classified as not hazardous in accordance with the Globally Harmonized System of Classification and Labelling (GHS)​

I've only read a few hundred MSDS documents in decades of teaching chemistry (and have been asked to write a few such), but in my experience the MSDS has as its major purpose the limitation of liability to the manufacturer. The manufacturer of cellulose insulation is clearly a bit more careful to limit their liability than the crepe paper manufacturer, possibly because cellulose insulation can be dispersed into the environment more than crepe paper can be.

Sorry, that's just the opinion of a chemistry Ph.D. with 42 years of teaching experience along with publication of two editions of one chemistry textbook and five editions of another. Plus two editions of another book that has had some relevance to rocketry...

Goodbye.

 

[lakeroadster]

I've only read a few hundred MSDS documents in decades of teaching chemistry (and have been asked to write a few such), but in my experience the MSDS has as its major purpose the limitation of liability to the manufacturer. The manufacturer of cellulose insulation is clearly a bit more careful to limit their liability than the crepe paper manufacturer, possibly because cellulose insulation can be dispersed into the environment more than crepe paper can be.

Sorry, that's just the opinion of a chemistry Ph.D. with 42 years of teaching experience along with publication of two editions of one chemistry textbook and five editions of another. Plus two editions of another book that has had some relevance to rocketry...

Goodbye.

Goodbye.? Don't get all pissy, and give us your resume.... just read the report.

 

[Tractionengines]

PISTONS FOR LOW POWER. Some changes from Mid or High power.

Pros: No dog barf. No Estes/Quest wading. No crape paper. Full protection of parachute. Quick to reset for next flight. Works on any size body tube (just need a coupler that fits and a bulkhead for inside the coupler). Pressure pushes out recovery, no need for nosecone inertia to pull it out.

Cons: Must be wiped down to make sure no buildup of black powder residue. Careful fitting during initial assembly. Be aware weather can effect fit. Not as easy on a minimum diameter rocket, (need to add an anchor above motor and below piston, taking up space).

For LPR, non-minimum diameter rocket:
* cut coupler length to .75 to 1.5 times body diameter.
* fit a bulkhead to middle of coupler.
* secure a small loop of kevlar thru bulkhead with access on both sides.
* Bring a kevlar cord up from bottom of rocket. ( motor mount, retainer, anchor point, etc.) Extend about 9-12" past end of body tube.
* protect cord from tube edge and prevent zipper by putting 2 layers if double wall adhesive lined heatshrink 1" long, over kevlar at end of body tube.
* connect kevlar to loop on bottom of piston with a swivel (for quick release )
* connect shock cord (whatever type you prefer) to loop on top of piston.
* (standard recovery "stuff" from here to nosecone.)

Preparing for flight:
*** make sure piston slides freely! ***
* Organize kevlar and slide into rocket.
* Slide in piston.
* Organize shock cord and slide into rocket.
* Pack parachute and slide into rocket.
* Install nosecone.
** make sure nosecone is tight enough to pick up rocket.

FLY ROCKET

POST FLIGHT:
* Disconnect swivel from piston.
* Pull kevlar back thru motor tube.
* Inspect kevlar
* Wipe residue from piston.
* Wipe out body tube.
* Reconnect swivel to piston.

Prep for next flight.

 

[DeltaVee]

Personally, I like baffles... I try and design them such that anything loose shakes out fairly easily... I give the "business end" and any surface that takes a direct hit a good coat of epoxy. Below is one I cobbled together:

 

[smstachwick]

Quick summaries of my opinions of selected further developments in the thread:

I cannot comment on baffles, pistons, or anything else. I have no experience with them.

I choose dog barf over TP every day of the week, except in unusual applications like fireproofing paper parachute protectors as are recommended in the old Alpha kits. I also endorse the use of dog barf in tubes up to and including BT-60, I've had good results in that size so long as I've used enough.

Regarding comparison to the fire blanket, here's where I think dog barf shines:

• Cost: $5 for a bale that will last a lifetime for an individual or a multi-year period for a typical club is going to be less expensive over either of those time periods than a series of blankets that you'll have to replace when your rocket gets lost. And don't fool yourself, at some point it will get lost, that's just part of what we do.
• Packing options. Dog barf can go in from the rear, which is important to me when I have ratty old tubes and uncooperative Estes chutes. If all of your rockets are pristine and you've got thin mylar chutes or something like that, that may be less important.
• Environmental concerns. Dog barf degrades safely in both the physical and chemical sense. DuPont's synthetic fibers won't leach any dangerous chemicals out into the environment as other synthetics will, but they may still prove environmentally harmful through physical degradation over the course of many years.

Here's where I think it will be difficult for dog barf to match the fire blanket:

• Big tubes, especially those used for MPR/HPR. A blanket will be lighter, take up less space, shift less during flight, and produce less risk of ejection failure in a tube bigger than, say, 54mm (2.1 inches). Safety considerations start moving in directions that make a blanket favorable as rocket size goes up.
• Storage space. It can be tricky to find a spot to keep a Homer bucket or a Lowes bale of the stuff in your house, your vehicle, or your range supplies. Then again, rocket supplies are essentially gaseous, expanding or compressing (to a point) to fill the available volume.

 

[OverTheTop]

https://www.rocketryforum.com/threads/paper-parachute-protectors.168048/