AT baffle/anchor/shock cord questions

[DynaSoar]

This is data collection. I'm looking for numbers from direct experience, not what someone did/would do instead.

Besides hearing how many have experienced these problems, if you have flown AT birds and NOT experienced them, that's an important data point too, and I'd like to know.

How many people have actually HAD to remove the steel baffling for cleaning? That is, found that the airflow was signifincantly reduced, cleaned a significant amount of stuff out of it, put it back and it worked better?

If so, after how many flights, what kinds of motors, and how much stuff came out? How much "better" did it work? If you could recognize what the stuff was, what was it (paper ejection charge cap pieces? dog barf?).


Also:

How many people have actually had an AT elastic shock cord installed on the anchor per instructions burn through, or break at or near the anchor with clear signs of significant burning?

Again, after how many flights, and what kinds of motors?


If any of these things did happen, and it might have had something to do with how you built it (glue on the shock cord, etc.) that'd be good to know.

 

[Chilly]

I've had an Arreaux for about two years and it's made at least a dozen flights. I've noticed the mesh is starting to corrode and has gotten to the point where rusted chunks of the stuff are falling out of the motor tube. The last time it flew, the chute got scorched in a couple of spots.
If I ever build another Aerotech kit I'll probably leave the mesh out and just use dog barf wadding. They'll take bigger motors that way, also.

 

[Habu]

I have a couple of stock Aerotech kits and one that I modified for a baffle. We won't consider that one unless it is important to say I elected away from the mesh system.
My Airspike has flown many (at least a dozen) times and only recently have I started to see debris begin to shake out from the motor tube. My Wart Hog hasn't seen as many flights but so far so good.
After each flight I try to remember to shake out the plastic or paper ejection cap.

The elastic shock cord hasn't given me any problems thus far.

 

[n3tjm]

I never had a problem with the mesh system... and I flown Aerotech rockets for many years, with D through H motors.

Make sure you stretch out the mesh before installing it into the motor tube. If you just cram it in there, it will clog up in no time with residue.

An interesting note: I have found the that mesh is not really necessary... I had Aerotech rockets where te mesh has completely disolved, and I still flew them.... have seen no damage to the shock cord or parachutes yet.

 

[loopy]

I've never had a problem with my AT cooling mesh. No damage to cord/chute, and I just shake the rocket out after every flight to get as much out as I can. After every third or fourth flight, I use a bent coat hanger to stretch the mesh back out a little, and I have yet to have any problems at all.

Loopy

 

[Initiator001]

I have built and flown dozens of Enertek/AeroTech prototype & production kits using the baffle system and have never taken the mesh out to clean it. I have also incorporated the cooling mesh into other companies' kits and my own scratch-build projects and have never removed the mesh for cleaning. I have had no problems with restricted ejection gas flow.

I have never had any problm with the plastic anchor for the shock cord. No buring/burn-through of the shock cord, either.

One thing that was discovered while testing at AeroTech was that if ANY glue/cement got inside the forward end of the motor mount tube and got in contact with the mesh, the mesh would hold the ejection charge heat for a time and the glue would act as a fuel. The result was charring or buring of the motor mount tube.

I do not allow any glue into the forward end of the motor mount tube. Rather, I put cement on the plastic baffle (after roughing it up with sandpaper) and insert the baffle into the tube. Any excess glue squeezes out where the motor mount tube meets the baffle flange.

 

[DynaSoar]

Originally posted by Chilly
I've had an Arreaux for about two years and it's made at least a dozen flights. I've noticed the mesh is starting to corrode and has gotten to the point where rusted chunks of the stuff are falling out of the motor tube. The last time it flew, the chute got scorched in a couple of spots.
If I ever build another Aerotech kit I'll probably leave the mesh out and just use dog barf wadding. They'll take bigger motors that way, also.

Corrosion is not a usual complaint. Did it land in water?

 

[DynaSoar]

Originally posted by n3tjm
I never had a problem with the mesh system... and I flown Aerotech rockets for many years, with D through H motors.

Make sure you stretch out the mesh before installing it into the motor tube. If you just cram it in there, it will clog up in no time with residue.

An interesting note: I have found the that mesh is not really necessary... I had Aerotech rockets where te mesh has completely disolved, and I still flew them.... have seen no damage to the shock cord or parachutes yet.

Completely dissolved? Yours corroded too?

I *did* mash mine in down to 2" on the Mirage, so I could set the thrust ring to fit Ellis Mountin H's. It didn't seem any harder to blow through at the time. I'll have to keep an eye on it.

 

[xenon]

I've flown my stock Arcas well over 20 times. I've never even looked at the baffle after I built it. It still works
I usually make sure the red ejection cap comes out when I remove the motor, but I guess it hasn't always. Other than that, I've never poked around at it or anything

Now that someone brought it up, I might just go look....

 

[xenon]

Okay, I just checked for the mesh. There isn't any! it all must have completely corroded. I wonder how many flights it has been like that

 

[DynaSoar]

Originally posted by xenon
Okay, I just checked for the mesh. There isn't any! it all must have completely corroded. I wonder how many flights it has been like that

Geez, does this count as a good thing or not?

The problem with data is that it's objective. Results aren't necessarily.

 

[Chilly]

I can say unequivocally that my Arreaux has never landed in water. Humidity, OTOH, could be just as much an issue over time.

 

[n3tjm]

Interesting how you don't need the mesh . What does a number on the mesh is not the ejection charge, but actually the dealy grain. When the charge goes off, whatever delay burnoff is left will shoot throungh the ejection hole... The delay element contin MANY corrosive ellements, including HCL.

 

[DynaSoar]

Originally posted by Chilly
I can say unequivocally that my Arreaux has never landed in water. Humidity, OTOH, could be just as much an issue over time.

Good data point. Heat flash starts oxidation, humididity continues it.

Good reason to try copper instead.

 

[DynaSoar]

Originally posted by n3tjm
Interesting how you don't need the mesh . What does a number on the mesh is not the ejection charge, but actually the dealy grain. When the charge goes off, whatever delay burnoff is left will shoot throungh the ejection hole... The delay element contin MANY corrosive ellements, including HCL.

Maybe copper won't work better then. Got a list of the chemicals involved?

 

[havoc821]

Had an F20 CATO in my Initiator and ejection charge went off 1 sec into burn and motor burned from both ends for about another sec and completely melted baffle assembly.

 

[rabidsheeep]

well, just for kicks i checked and the mesh is alittle messed up, and the red cap was still stuck in

im gonna ask my dad to get me a probe (long kelly clamp) from the hospital to rip out the mesh and ill just use wadding

 

[Stymye]

can you just drag the old piece out with a hook and shove annother new one in?
I'm looking in the back of my warthog and it appears pretty easy to change out. I imagine the stainless steel would probably be the thing to use. copper corrodes too easily.

 

[DynaSoar]

Originally posted by xenon
I've flown my stock Arcas well over 20 times. I've never even looked at the baffle after I built it. It still works
I usually make sure the red ejection cap comes out when I remove the motor, but I guess it hasn't always. Other than that, I've never poked around at it or anything

Now that someone brought it up, I might just go look....

"Red ejection cap"? You use the cap to cover the ejection port, right?

Plastic WOULD gum the works up. Is there an alternative? Masking tape?

 

[Habu]

Some in our club have used masking tape but I don't think it was due to a concern for the plastic cap getting stuck in the mesh...
they probably had lost the cap.

 

[loopy]

After the flight, I take the motor out, then shake the rocket out to make the ejection cap drop out. The mesh will wear out after awhile, but is easily replaced with another mesh from the "Chore Boy" thing. That's all that mesh is.

Loopy

 

[ssthor]

I have a minimum of 12 launches on my Initiator (stock) and 6 on my Arreaux (stock). All flights have used RMS engines F & G.

1. I have not experienced any meshing issues at this time. As others had stated, I make sure that the red ejection cap falls out after each flight. After each launch day, I use a clothes hanger with a very small bend at the end to stretch out the mesh. When I do this, a few small mesh "curlies" fall out. I will eventually replace it with chore boy.

2. Regarding the shock cord, everthing has work as intended. Because it is a concern of mine, I perform a visual check with a flashlight. I have noticed a slight graying on the cord near the baffle eye. However, it is difficult to determine if it is burn damage or just residue since the cord is black. When the need comes to replacing the cord, I will most likely use white.

So far so good!

 

[Stymye]

I use masking tape to contain the ejection, no scientific reason , just had a few caps that didn't fit well, and "stuck" with the tape ever since than . In the case of the aerotech baffle ,This may be a slight benefit as the tape "usually" stays with the casing.