So, maybe I'll try a three-stager

Someone's missing their kids toy walrus

Nytrunner said:

Someone's missing their kids toy walrus

Click to expand...

It's a seal......a wineryseal

TonyL said:

Hi Jim,
your brewery filter is nice and all, but did you get one of these?
It came free with the order. I got the 2" and the 1.5" in case they were different [suppose I could have asked but I tend to order parts around midnight...]. The 1.5" is $1.50 cheaper.
br/
Tony

Click to expand...

I ordered exactly the same sizes...., at around the same time...., and wondered if they actually were different sizes....

No walrus....

G'Jim

So, here is a quick video of the test of the basket (and my pellets). The test was fine, but Stu is worried about the basket coming out of the motor (or rather, getting stuck at the nozzle). I'm just not sure what the strategy should be here.

The test was with 5 grams of pellets versus 9 grams for the flight.

Jim

Why would it come out of the motor?

Heat weakening and parts being melted off?

JimJarvis50 said:

So, here is a quick video of the test of the basket (and my pellets). The test was fine, but Stu is worried about the basket coming out of the motor (or rather, getting stuck at the nozzle). I'm just not sure what the strategy should be here.

The test was with 5 grams of pellets versus 9 grams for the flight.

Jim

Click to expand...

Impressive as always. Thanks for keeping us updated. Two thoughts:

Basket getting stuck at the nozzle: The solution would present itself if you weren't doing HEI: attach the basket to the rod holding the igniter in. The rod would ensure proper orientation. Since that isn't the case, two alternatives come to mind. First, have a rod anyways. Perhaps all the way to the nozzle, or perhaps just long enough to ensure proper orientation at the nozzle. The second would be to retain the mesh basket and attach it to the forward closure so that I won't be ejected as a whole (it will probably still be ejected as the heat of the motor destroys it, but hopefully it will come out in chunks that won't foul the nozzle.)

The nozzle itself: The purpose of the basket is to allow for full combustion in a thin atmosphere so that the motor can come up to temp/pressure. Have you considered using a wax semi-plug at the throat to reduce the throat diameter? It would hold combustion products in a little longer, but the moment the motor came up to a sustaining temperature/pressure, the high flow rate/temp would immediately ablate away all the wax.

Hi Jim,

Lacking any flight history, you should plan for it to pass through the nozzle in some form because it is thin wire. If it is anchored well enough that it has to melt to get free, the pieces will be small. If big parts of the basket come free, that would probably cause problems. Do the pellets melt the wire? If they don't, then they shouldn't cause the end to drop off, and the whole thing should generally melt at once, keeping the pieces small. Unfortunately testing is the most reliable [and usually costly] way of sorting out this type of thing.

br/

Tony

I would definitely NOT try reducing the nozzle with wax or anything else to manage pressure without some serious testing, unless your goal is 'some sort of event'.

That looks identical to my test in a 10-mesh ss basket. If the rim of mesh is spread out and captured in a collar fastened to the forward closure, it won't come off.

Thanks John, good to know.

jsdemar said:

That looks identical to my test in a 10-mesh ss basket. If the rim of mesh is spread out and captured in a collar fastened to the forward closure, it won't come off.

Click to expand...

I can use the half of the filter that has the flanged base (i.e., the flanged base and about 3" of the basket). In addition to the flanged base, this approach will avoid the use of the curved portion of wire at the end of the filter. I can see that possibly coming loose. The flanged base can be attached to the closure such that the basket won't come out. Since the cyliner is now open, I'm planning to use 0.025 safety wire to weave a "top" for the basket and also a support at about the mid point of the basket, and the pellets will sit between those supports (extending an inch or so into the top of the first grain).

In the test, the basket itself doesn't seem to have any damage to it. It's just charred. Hard to say for sure though. The 0.032 nichrome safety wire was not damaged at all. I'm going to go from 0.032" to 0.025 for the safety wire, just to make it a little easier to fabricate the supports.

Jim

So, here's what I ended up doing. I trimed the wire flange to go around my contacts and then screwed it down to the epoxy (probably not necessary, as I ended up potting the assembly in epoxy). I'll put in "bulkheads" of safety wire about mid-way up the basket and at the top of the basket to contain the pellets. I have a couple of BKNO3-dipped ematches, and I'll probably just run them up the side of the basket and in through the top.

Jim

Jim,
Excellent work, I would not change anything structurally. If you think you will want it reusable, extending the terminals above the epoxy on the next one might be an idea.

br/

Tony

TonyL said:

Jim,
Excellent work, I would not change anything structurally. If you think you will want it reusable, extending the terminals above the epoxy on the next one might be an idea.

br/

Tony

Click to expand...

Initially, I potted the epoxy such that the terminals were still usable. It wasn't a very thick coating of epoxy (see pic) , so I just filled the well. We have another forward closure if need be.

Jim

JimJarvis50 said:

Initially, I potted the epoxy such that the terminals were still usable. It wasn't a very thick coating of epoxy (see pic) , so I just filled the well. We have another forward closure if need be.

Click to expand...

How about using silicone for the second step in the potting process? The epoxy in the first step ensures that everything is kept in place and able to handle the pressure, whereas the silicone is more resistant to heat and also easier to remove for refurbishment.

Reinhard

Reinhard said:

How about using silicone for the second step in the potting process? The epoxy in the first step ensures that everything is kept in place and able to handle the pressure, whereas the silicone is more resistant to heat and also easier to remove for refurbishment.

Reinhard

Click to expand...

Yeah, could have done it that way, and it would have been fine.

In other news, I have completed the wiring harness for the rocket. This rocket is unusual because all of the control is from "Kate 2" in the nose cone. So, the wiring to all of the charges, which are located on a bulkhead, along with the sustainer ignition wiring, have to pass through the main chute bay. There are fittings that will let go when the sustainer drogue charges fire and when the nose cone separates. I will never be known for my wiring, so I apologize in advance for those of you that get offended by my work.

In other minor news:

- The actual Kate 2, not the prototype, is now in my hands for some testing this weekend. Thanks to Vern for putting together this wonderful device.
- The P and O motors have been completed. Everything fits. Stu did these, but I helped a little.
- Our Class 3 paperwork is back from Tripoli, ready to be submitted to the FAA.

The only major construction step at this point is to apply ablative to the cone and fins. We'll see how that goes.

Jim

What do you use for breakaway co nectors?

Nytrunner said:

What do you use for breakaway co nectors?

Click to expand...

They are something called Dean's micro plugs:

https://www.hobbytown.com/deans-micro-plug-2nb-black-nonpolarized-connector-reversible-wsd1225/p3593

They are exactly the form factor that I want. I just sand the prongs a little until I get just the fit I want.

Jim

Well, the Balls rocket is pretty much complete...., almost. I completed the head end ignition "basket" and I also added some redundant electronics just in case Kate has a brain freeze (not going to happen though). I have everything ready for transport, and what is left is essentially packing. Almost.

The almost part of this is the ablative. I went ahead and popped for the Firex Rx-2376. It isn't cheap, and they didn't exactly give me a lot of it. At the moment, I don't have a complete plan for applying it.

Part A is like cold honey. This is the part that contains the isocyanates (m-tolylidene diisocyanate to be specific). Part B is mostly a suspension of ammonium oxalate solids, triisopropanolamine (a urethane I believe) with methylene chloride as the solvent. Oh, Joy. The material is supposed to be sprayed on, but the combination of A/B is sort of like thick epoxy when mixed. It would have to be cut with more methylene chloride in order to be sprayed.

Given that I don't have much of this, I was hoping to apply it with a roller. I found one that doesn't immediately swell up upon exposure to methylene chloride, but my first pilot attempt didn't go too well. The problem seemed to be that the methylene chloride evaporates so quickly that the material gets too thick and gloppy to spread out. I'm going to try to thin it out a little for the next try. If that doesn't work, maybe a brush would work, but applying this is like painting with paint that dries in about 5 seconds. I was wondering about using a hard roller of some sort to smooth it out before it sets up. Hmm.

Ideas on how to do this would be appreciated.

Jim

Good luck with the project Jim . Keen to hear how the ablatives go.

I probably shouldn't have to mention it but please use an exceptionally well-ventilated area when applying this. Forced extraction too would be my approach to this stuff. That stuff is a likely carcinogen, and metabolises to carbon monoxide .

Jim,
also be very careful about glove choice as isocyanates and methylene chloride probably have different permeation properties and both are indeed quite nasty. Silvershield gloves are impervious to almost everything, just that they are awkwardly shaped. You might try wearing a cpap type or other air supply setup unless you are confident in your organic vapor cartridges. You can get a tyvec hood pretty cheap plus a fan and a hose as one concept I was seriously looking at when I thought I would need to work in a poorly ventilated space.
br/

Tony

TonyL said:

Jim,
also be very careful about glove choice as isocyanates and methylene chloride probably have different permeation properties and both are indeed quite nasty. Silvershield gloves are impervious to almost everything, just that they are awkwardly shaped. You might try wearing a cpap type or other air supply setup unless you are confident in your organic vapor cartridges. You can get a tyvec hood pretty cheap plus a fan and a hose as one concept I was seriously looking at when I thought I would need to work in a poorly ventilated space.
br/

Tony

Click to expand...

I really don't have any choice but to do this outside (still taking the above precautions). It just aggrevates the problem or the methylene chloride evaporation (it's a bit warm in Texas this time of year).

Jim

TonyL said:

Jim,
also be very careful about glove choice as isocyanates and methylene chloride probably have different permeation properties and both are indeed quite nasty. Silvershield gloves are impervious to almost everything, just that they are awkwardly shaped. You might try wearing a cpap type or other air supply setup unless you are confident in your organic vapor cartridges. You can get a tyvec hood pretty cheap plus a fan and a hose as one concept I was seriously looking at when I thought I would need to work in a poorly ventilated space.
br/

Tony

Click to expand...

You aren’t kidding. Methylene chloride is nasty stuff. Suspect you already know this, but for others following the thread....

Skimmed the following from MDS
https://www.atmos.umd.edu/~russ/MSDS/methylene_chloride.htm


Skin Protection:
Wear impervious protective clothing, including boots, gloves, lab coat, apron or coveralls, as appropriate, to prevent skin contact. Neoprene is a recommended material for personal protective equipment. Natural rubber and polyvinyl chloride ARE NOT recommended materials for personal protective equipment

So, the ablative is going to be applied this weekend. I hope. I'm going to be able to use a fume hood at work. That solves a lot of problems, but I still need to determine how to apply it. The best idea I have at the moment is to use a spray bottle of some sort - something with a trigger that you might use to spray a plant for example. I just need to find the right kind of bottle. Something that delivers a coarse spray and that will stand up to the methylene chloride, at least for long enough to do the application.

Jim

Once again, Tony (TFish) was deeply involved in the recovery of one of my rockets. At least this time, we arrived at the rocket at the same time (he usually gets there first). This was the P to O two-stager. The flight was on Saturday around noon. We didn't get the altitude we wanted, but everything worked and recovered as planned. Given the carnage over the weekend, we are fortunate, as most of the large projects had issues! There will be a video, but here's a teaser to start with (Pad Cam by Peter Thoeny).



Jim

JimJarvis50 said:

Once again, Tony (TFish) was deeply involved in the recovery of one of my rockets. At least this time, we arrived at the rocket at the same time (he usually gets there first). This was the P to O two-stager. The flight was on Saturday around noon. We didn't get the altitude we wanted, but everything worked and recovered as planned. Given the carnage over the weekend, we are fortunate, as most of the large projects had issues! There will be a video, but here's a teaser to start with (Pad Cam by Peter Thoeny).

Click to expand...

Congratulations Jim!!! Glad to hear you did well, I was a bit worried as it did seem like there was a lot of carnage around.

Congrats!

Outstanding Jim! Now show us how to do 3.

Nice job!

the other unrecognizable Jim! lol don't feel bad, a lot of folks I know,didn't know me either.......

blackjack2564 said:

Nice job!

the other unrecognizable Jim! lol don't feel bad, a lot of folks I know,didn't know me either.......

Click to expand...

You might be interested to hear that it took the pellets
5 seconds to light the motor! Maybe you have better pellets.

The other Jim