Baffles instead of wadding for HPR?

[billdz]

During my summer in Slovakia, I came to appreciate the baffles on Klima rockets, which make wadding unnecessary. I was wondering if baffles can be used for HPR, have never seen them on a big rocket. There must be some disadvantage to baffles, otherwise more people would be using them. They worked great for me.

If you have never seen baffles, see
https://www.modelrockets.co.uk/shop...le-kit-for-bt-70-no-more-wadding-mp-1251.html

 

[rharshberger]

Baffles can and have been used in HPR rockets, both as baffles and chute shelves to keep the laundry from sliding deep into the parachute bays of larger rockets.

One thing to watch out for is the Aerotech Red Caps will beat a baffle up pretty quickly.

 

[tfish]

I've played around with Baffles in rockets. It was a really simple system. Stainless Steel scrubbing pad from the "Dollar" store. Tied it on to my shock cords of a couple of 54mm and 3" min dia rockets. Figured I'd do away with the dog barf and or Nomex. I ran the ematches down between the top of the motor and my laundry. One thing I did not take into account was...that the hot gasses passing through that SS mesh are not the same volume as when using bog barf and or Nomex.

So, if you switch to a baffle system from Dog barf/nomex...re=do your ground tests!

Tony

 

[Binder Design]

The stock Velociraptor kit uses a baffle.

 

[dhbarr]

Qualman makes some pretty ones.

 

[Rex R]

I have done a couple of 3" dia.(38mm motors) rockets* w/ baffles, another thing to watch out for is ejection well caps/covers getting stuck on the lower baffle plate and clogging things up for subsequent flights.
*note a piston can be considered as a form of baffle.
Rex

 

[T-Rex]

A couple of my larger rockets use a baffle. Our ceiling is 2000ft so I don't use dual deploy (though I have started using a JLCR). What I have done is extend the motor mount tube and build the baffle there. I use the half-moon type made popular by qquake2k. Yes it restricts the size motor that I can use, but in my case that is not an issue.
I also use tape on my charge so the red cap is a non-issue. Even with a baffle, I have blankets in all my birds. Paranoid I guess....

 

[cbrarick]

nomex blankets. Even in kits that have baffles, the first step for me is to fish out the baffle parts and put them in my spares box. I never use them.

 

[Nathan]

Wadding? I don't think I have ever seen dog barf wadding used in anything bigger than 3" diameter tube.

For baffles I would be concerned that the hot ejection gasses passing through the baffle might still damage the expensive HPR chute. So even with a baffle I would also still use a chute protector.

 

[Rex R]

hot gases are not (usually) the problem they just don't contain enough heat, it is the burning chunks that are the problem. a baffle might not stop the chunks but, it should slow them down to the point that the chute has left the rocket before they arrive. in larger rockets the wadding(dog barf) appears to act as a temporary baffle.
Rex

 

[Bat-mite]

The only disadvantage I can see for baffles in larger rockets is the cost to buy them (fiberglass isn't cheap), the time necessary to install them, and the added weight, if that is a concern.

 

[Handeman]

Wadding? I don't think I have ever seen dog barf wadding used in anything bigger than 3" diameter tube.

For baffles I would be concerned that the hot ejection gasses passing through the baffle might still damage the expensive HPR chute. So even with a baffle I would also still use a chute protector.

You need to come see mine. I use dog barf in my 4" and 6" rockets. I have a D-bag for the 6", but still use dog barf. I have a few chute protectors with holes burned in them and matching holes in the chutes. With the $100+ for large chute in the 6", dog barf is really cheap insurance. In the 4" I use an old hole filled protector so the dog barf is what really protects the chute. I'm almost 2/3 of the way through a bale of dog barf, but I bought it 10 years ago so that ain't too bad. The way I see it, it works, it's cheap, and the residue isn't as bad as the BP residue so it's all good.

 

[rharshberger]

You need to come see mine. I use dog barf in my 4" and 6" rockets. I have a D-bag for the 6", but still use dog barf. I have a few chute protectors with holes burned in them and matching holes in the chutes. With the $100+ for large chute in the 6", dog barf is really cheap insurance. In the 4" I use an old hole filled protector so the dog barf is what really protects the chute. I'm almost 2/3 of the way through a bale of dog barf, but I bought it 10 years ago so that ain't too bad. The way I see it, it works, it's cheap, and the residue isn't as bad as the BP residue so it's all good.

+1, I use Dog Barf as well in my 5" Cherokee-D however a containment like a fire retardant treated paper towel as a "cup" keeps the dog barf from settling down around the charge wells. Both the paper towel and the dog barf a pretty enviromentally friendly.

 

[LOC]

I personally LOVE Baffles. However, some of my colleagues do not! We always have mud slinging at launches. But really. I love them. Yes, sometimes you need a bit more black powder and strong than average motor retention. But not worrying about dog barf is worth it to me!!! We have a few kits with included baffles and to me it's a common sense approach. But! As anything in this hobby, it's always a healthy debate!

 

[Handeman]

I personally LOVE Baffles. However, some of my colleagues do not! We always have mud slinging at launches. But really. I love them. Yes, sometimes you need a bit more black powder and strong than average motor retention. But not worrying about dog barf is worth it to me!!! We have a few kits with included baffles and to me it's a common sense approach. But! As anything in this hobby, it's always a healthy debate!

I have a few rockets with baffles, but not many. Sometimes I find myself putting dog barf down over the baffle.... Not a problem with pistons. I like those better.

 

[jimzcatz]

I refuse to use baffles. I am 100% nomex protectors now.

 

[tbonerocketeer]

Wadding? I don't think I have ever seen dog barf wadding used in anything bigger than 3" diameter tube.

For baffles I would be concerned that the hot ejection gasses passing through the baffle might still damage the expensive HPR chute. So even with a baffle I would also still use a chute protector.

I fly orange crush with barf...7.5" diameter rocket on a P motor. I even use it when I use a nomex protector. Makes them last longer that way(blew a hole in one first use with a 6g charge)

 

[jodykid]

Since the Gods at PML blessed Humans with the knowledge of the miracle of pistons why would anyone use anything else? I use them on everything down to BT20 size rockets.


Joe

 

[djs]

It's my understanding that pistons can have issues in colder weather due to one part (piston) contracting at a different rate than a different part (body tube), resulting in stuck pistons. Not sure where you fly, but in the upper midwest, we'll fly when it's below freezing out.

 

[3stoogesrocketry]

It's my understanding that pistons can have issues in colder weather due to one part (piston) contracting at a different rate than a different part (body tube), resulting in stuck pistons. Not sure where you fly, but in the upper midwest, we'll fly when it's below freezing out.

That and you need to be able to clean the inside of your rocket periodicly . All the BP reside will cause the piston to get tighter and/or even get stuck.

Eric

 

[jodykid]

Central and Southern California where I launch rarely gets to freezing. Mostly in the 80's to 118 or so. And yes pistons do need cleaning now and then. Only problem I've had was one rocket with a sloppy piston fit and a very thin fabric chute that caught the chute skirt between the piston and airframe. Came down spinning sideways with minimal damage.

Joe

 

[jimzcatz]

Since the Gods at PML blessed Humans with the knowledge of the miracle of pistons why would anyone use anything else? I use them on everything down to BT20 size rockets.


Joe

Don't get me started on pistons! They are worse than baffles. Just mho of course.

 

[LOC]

It is cool how different things work for different climates and everyone has an opinion. It's what keeps the hobby rolling imo!

 

[Handeman]

It's my understanding that pistons can have issues in colder weather due to one part (piston) contracting at a different rate than a different part (body tube), resulting in stuck pistons. Not sure where you fly, but in the upper midwest, we'll fly when it's below freezing out.

I agree about the weather, especially with PML kits and the Quantum tubes. Of course you don't want to fly them in very cold weather because the BT will snap like a Candy Cane in cold weather. We won't talk about that.

What I do know, once you get the piston sanded down so it works in cold weather, it works even better in warm. Get is set for the coldest weather and you never have to adjust it again. You might need to clean the tube, but....