Piston, Baffle, or Wadding?

[Hospital_Rocket]

So lets take a brief survey.


What is the best MPR/HPR recovery system?

 

[BlueNinja]

I'd say a baffle. Pack chute and insert motor.

 

[Ryan S.]

I think dog barf because you can really get full protection of your chute with it

 

[RocketboyG80]

I use a combo of a Nomex heatshield just under the chute and some starch packing peanuts in the bottom. This provides excellent protection... in my experience. Plus the heatshield reduces the amount of disposable wadding you have to lug around. If it starts to get crusty you can just wash it with some soap and water. Good poll idea BTW.

 

[Rocketmaniac]

For Mid-powered I use the dog barf........ For High-powered I use a combo of Nomex shields and dog barf............

 

[lalligood]

hmmm... How about "None of the above"?

I voted for piston system, as it has worked extremely well in my PML Phobos, but I'm also fortunate enough to live in a climate where I don't have to worry about Quantum tubing shrinking with cold temperatures--as it rarely gets below 40 degrees here & if it does, it only lasts for a couple of days at most!

That aside, I love my CD spool rockets, saucers, & new 29mm Qubit because they DON'T REQUIRE ANYTHING AT ALL (Oh yeah, I have a cloned Estes Sputnik that doesn't need anything either!) *Those* are my favorites!

 

[bobkrech]

Definately an anti-zipper designed baffle for any rocket with motor ejection.

This configuration virtually guarantees 100% separation if the ejection charge goes off, and if the chute is attached to the shock cord near the eyebolt on the baffle, the NC/BT is blown clear and the chute is far less lickely to strip on any early or late deployment.

Bob Krech

 

[rocket877]

Originally posted by lalligood
hmmm... How about "None of the above"?

That aside, I love my CD spool rockets, saucers, & new 29mm Qubit because they DON'T REQUIRE ANYTHING AT ALL (Oh yeah, I have a cloned Estes Sputnik that doesn't need anything either!) *Those* are my favorites!

I agree with you Lance. Aerobrake is the most relliable recovery systems.

I would like to see some of your CD spool rockets. Perhaps we can collaborate on a kit.

 

[cls]

OK, here's one vote AGAINST piston systems.


Saturday my daughter's Sumo, on the 2nd flight: at ejection the piston stuck, the shock cord burned stretched & broke, the nose & parachute flew away, the motor blew out the back (29/240 H97) & disappeared, and the MMT & fin-lock system was destroyed, the booster section tumbled & stuck a fin in the mud.

piston systems suck.


all parts were recovered thanks to friendly rocketeers. (my 29/240 didn't even get a scratch on it.)

I have a length of 29mm MMT so we will rebuilt the Sumo BUT STILL!!!! GEEZE!!! I am sure unimpressed by pistons.

 

[Hospital_Rocket]

Cliff

I'm going to do my L1 with a Sumo, and after spemding hpurs trying to sand that "piston" that came with it down far enough to fit, I just gave up. I modroc'd it to fasten a steel cable to the eve at the top of the MMT. The cable ends even with the end of the body tube and I attach the shock cord there. I added a Thrustline Nomex shield to augment the baffle, and will see what happens there.

I re-used the piston part to reinforce the tail of the Sumo.


On the flip side, my PML piston in a MINI-BBX seems to work flawlessly.


Al

 

[cls]

Hospital-Rocket,

"the cable ends even with the end of the body tube" sounds like a zipper-machine to me!

good idea to use the coupler on the back end. although, the rocket is sturdy enough as-is. those fin-loks work well.

I am glad to hear your PML has worked well, I saw a bunch fail at a launch recently.

good luck with your L1!!

 

[PGerringer]

I use dog barf and Nomex.

 

[Hospital_Rocket]

Originally posted by cls


"the cable ends even with the end of the body tube" sounds like a zipper-machine to me!

2.376

Actually I lifted the idea from a Nike Apache by Cosmodrome. The net effect is to move the anchor point of the shock cord to a point essentially flush with the end of the BT. Of course 20' of tubular nylon at the end of that does not hurt either

Of course, it's all about seeing if what comes down resembles what you sent up.....

A

 

[bfraley]

I've had good luck with pistons. But they need to be installed correctly or they can jam easily. See...

https://www.deltavrocketry.com/piston.htm

 

[bobkrech]

I've had good luck with pistons. But they need to be installed correctly or they can jam easily.

A really valuable observation backed by solid experimental evidence and a good theoretical explanation of why pistons jam.

The proper piston orientation is counter-intuitive at first, but make sense if you think about it.

Bob Krech

 

[hokkyokusei]

They all have their own pros and cons.

Personally, I've never had a problem with pistons. You need to verify that they run smooth. I typically test that I can push everything out by blowing ionto teh motor mount. But than i do that no matter the recovery system in use (excpet CPR - natch). Having said all of that, I've only ever used phenolic/phenolic pistons. I can see the logic in those that say phenolic and quantum have differing expansion rates.

So what do I typically use? If it's a kit, I'll use whatever it came with, if I'm scratch building, I generally use nomex.

 

[Dbarrm]

I dont mean to sound dumb but what is a barf bag???

Dan

 

[lalligood]

Originally posted by Dbarrm
I dont mean to sound dumb but what is a barf bag???

Dan

I think you meant "dog barf"...

It's insulation made with recycled newspaper. You can find it in your local home improvement store. A massive brick of the stuff (the only way it comes) will last you & an entire club of active rocketeers a LIFETIME to use...all for ~$8

The name comes from the appearance of the stuff when it's loose. Thankfully it lacks any resemblance to the texture and/or smell of the real thing!

 

[Dbarrm]

Thanks. Hell if I know where I came up with barf bag. I think I need more sleep.

Dan

 

[Stones]

Nomex.
Barf where the BT doesn't accomodate the Nomex.

 

[Chilly]

I'm experimenting with a combination baffle & nomex shield now. I built a baffle with a coupler sleeve, bulkhead, and stainless steel scouring pad (a la Aerotech). The scouring pad was unrolled and put in the sleeve, and I epoxied the bulkhead (with eyebolt) to one end of the coupler. The bulkhead was then drilled with six 1/4" holes.

The whole shebang attaches to the motor mount's forward centering ring, and then kevlar shock cord is attached to the eyebolt on the forward bulkhead. For good measure I'm putting a nomex heat shield at the parchute bridle. It could've been made a "zipperless" design as well but I didn't think it through far enough.

If it works I may build my Mini BBX this way & just use the piston parts to build the baffle. Considering the temperature extremes we get I'd rather not fiddle around with a piston system.

 

[Habu]

I'd agree with this.
I use baffles wherever I can in my modrocs and
in all of my MPR's and HPR's.
I also recommend the zipperless construction when possible.
The nomex is good insurance, a deployment bag is nice if you are using a big enough BT to accommodate one.

I haven't ever used pistons.
But I have seen them fail.
I have also had a baffle blow completely out on one occasion.
Completely recovered and the baffle was the only damage to the rocket.

 

[Johnnie]

Dog barf!

Bought a brick of it in 1997, and have yet to use a 1/4 of it. Cost of wadding at Home Depot in 1997 $3.67...rockets and parachutes it has protected...priceless.

Don't do sticky pistons, and have yet to try nomex...

 

[Sirius Rocketry]

Who came up with the term "dog barf" anyway? I would love to know the history of that one! For some reqason, it sounds like a Bob Kaplow invention to me!

 

[rdbones]

I voted for the Piston - I have not had a problem with the one in my Small Endeavour, and am putting one in my scratch built L1 bird.

With that said, I have used all of the above systems, and have found that each one has pro's and cons.

 

[Hospital_Rocket]

Who came up with the term "dog barf" anyway? I would love to know the history of that one! For some reqason, it sounds like a Bob Kaplow invention to me!

Really, my dog has never barfed up anything that easy to clean up.

 

[noise]

I voted permanent wadding, but I've had success with baffles too. No HPR yet though, so my opinion may change.

 

[Rock_It]

Dog barf for LPR.

Baffle for MPR.

Chute Protector or D-Bag for HPR.

 

[CraigF]

Nomex: reliable, easy, cheap. Baffle is second, somewhat heavier. Wadding is OK for real small stuff, I only use whatever I get included in sets (can't buy barf here). Haven't used a piston yet. This is L/MPR.

 

[TWRackers]

Who came up with the term "dog barf" anyway? I would love to know the history of that one! For some reqason, it sounds like a Bob Kaplow invention to me!

At least they didn't start calling it "cat barf". Now that's stinky. :vroam:

I've actually had good success with the pistons in my two PML rockets, and I did flip the pistons around as described in the deltavrocketry web site. But baffles, once installed, are mostly maintenance-free, as long as you occasionally shake the burnt particles out of them.