AeroTech Open Thread

[Theory]

yes, plastic wrap is also what I use.

 

[rfjustin]

I don’t know how to avoid it. You have to apply the glue to the grain and then slide it into the liner. That leaves some glue on the liner where the nozzle goes. You then have to stack the grains on the nozzle. Granted, I’ve only bonded the grains to the liner 3-4 times, but I really don’t see how to keep the nozzle from getting bonded to the liner in the process.

Go to a big box store and get a long dowel rod, just smaller in diameter than the the core of the grains of the K-1000. One swift smack against the nozzle, I bet that puppy will pop right off the liner.

 

[Art Upton]

On a somewhat related note, what nozzle should the M685 have? I’m building both the M685 and the K1000 at the same time and I’m now second guessing whether I somehow switched the nozzles.

 

[Jmhepworth]

The nozzle that I’m pretty sure came with the M685 is a single throat.

 

[Antares JS]

I don’t know how to avoid it. You have to apply the glue to the grain and then slide it into the liner. That leaves some glue on the liner where the nozzle goes. You then have to stack the grains on the nozzle. Granted, I’ve only bonded the grains to the liner 3-4 times, but I really don’t see how to keep the nozzle from getting bonded to the liner in the process.

Install the nozzle into the liner, stand it up vertically, nozzle-side down, and load the grains from the forward end. Press the grains down a bit after loading the last grain to make room for the seal disk, and wipe off any adhesive on the inside forward end with a baby wipe.

I've done all my grain bonding that way and as a side effect, never had a stuck nozzle because the adhesive never contacts it.

 

[Art Upton]

The nozzle that I’m pretty sure came with the M685 is a single throat.

Newer ones could be, they seemed to be switching to those.

 

[AeroTech]

A new dealer for our Australian customers:

 

[Jmhepworth]

Go to a big box store and get a long dowel rod, just smaller in diameter than the the core of the grains of the K-1000. One swift smack against the nozzle, I bet that puppy will pop right off the liner.

It did pop right off. So now do I drill out four of the holes?

 

[Jmhepworth]

It did pop right off. So now do I drill out four of the holes?

I measured the diameter of the center hole. It’s about a half inch, Which is more than the .359” in the drawing. Incidentally, the diameter is nearly (if not exactly) the same as the other nozzle with a single hole. So right now I’m inclined to reassemble the motor, cross my fingers, and send it. Nothing in the assembly instructions said anything about drilling holes in the Medusa nozzle.

 

[jmasterj]

I measured the diameter of the center hole. It’s about a half inch, Which is more than the .359” in the drawing. Incidentally, the diameter is nearly (if not exactly) the same as the other nozzle with a single hole. So right now I’m inclined to reassemble the motor, cross my fingers, and send it. Nothing in the assembly instructions said anything about drilling holes in the Medusa nozzle.

You can calculate the total area of the nozzles in the drawing and compare that with the total area of the nozzle you have.

 

[Jmhepworth]

You can calculate the total area of the nozzles in the drawing and compare that with the total area of the nozzle you have.

That requires math. Retired lawyer here. Assuming my math is correct (huge assumption, I should add), the drawing has a total of 714 mm and the nozzle I have has only 506. That’s millimeters squared, but I can’t figure out how to do that on my iPad.

 

[rfjustin]

It did pop right off. So now do I drill out four of the holes?

Hold for @AeroTech to confirm you are good to go.

 

[Jmhepworth]

I measured the diameter of the center hole. It’s about a half inch, Which is more than the .359” in the drawing. Incidentally, the diameter is nearly (if not exactly) the same as the other nozzle with a single hole. So right now I’m inclined to reassemble the motor, cross my fingers, and send it. Nothing in the assembly instructions said anything about drilling holes in the Medusa nozzle.

Gary, I could use some guidance here.

 

[rfjustin]

Install the nozzle into the liner, stand it up vertically, nozzle-side down, and load the grains from the forward end. Press the grains down a bit after loading the last grain to make room for the seal disk, and wipe off any adhesive on the inside forward end with a baby wipe.

I've done all my grain bonding that way and as a side effect, never had a stuck nozzle because the adhesive never contacts it.

That's how I prefer to do mine as well.

 

[Jmhepworth]

That's how I prefer to do mine as well.

If I ever do another one, that’s what I will do as well. I’ve always stacked the grains, secured them with cellophane tape, and then slid the liner down over the stack. I’ve liked doing it that way because I could make sure the spacer O rings were in the right place. But however I do it, I will make sure that the nozzle are is clean.

 

[DAllen]

Hey hurry up and get that L1090 made so Wildman can send my BF order pretty please.

 

[cls]

I’m pretty frustrated with myself right now. Perhaps I should just go back to A8-3s.

Make a cluster of 2500,That would be an M.

 

[WILDMANRS]

That requires math. Retired lawyer here. Assuming my math is correct (huge assumption, I should add), the drawing has a total of 714 mm and the nozzle I have has only 506. That’s millimeters squared, but I can’t figure out how to do that on my iPad.

Call Karl

 

[tjsnakez]

I have a K1000 with a Medusa nozzle. Only the center hole is open; the other six are closed. Is that what it should be?

They came that way for a period before switching to the single throat nozzle to allow usage in CTI cases. It's the correct nozzle.

 

[rokit]

That requires math. Retired lawyer here. Assuming my math is correct (huge assumption, I should add), the drawing has a total of 714 mm and the nozzle I have has only 506. That’s millimeters squared, but I can’t figure out how to do that on my iPad.

Can iPads do Excel? I think I got this link from a post from tfish:

https://info-central.rocketlabdelta.com/archive/propulsion_atmedusa.html

 

[Theory]

Hey hurry up and get that L1090 made so Wildman can send my BF order pretty please.

Is that whats holding my order up too????

 

[Theory]

If I ever do another one, that’s what I will do as well. I’ve always stacked the grains, secured them with cellophane tape, and then slid the liner down over the stack. I’ve liked doing it that way because I could make sure the spacer O rings were in the right place. But however I do it, I will make sure that the nozzle are is clean.

this is how I do it. easy for one person

 

[AeroTech]

I have a K1000 with a Medusa nozzle. Only the center hole is open; the other six are closed. Is that what it should be?

K1000T originally had 4 of the outer throats opened, but I believe we went with a larger center throat only so they would work as a Crossload.

 

[Jmhepworth]

K1000T originally had 4 of the outer throats opened, but I believe we went with a larger center throat only so they would work as a Crossload.

Thanks. That’s consistent with what I’m seeing. And it’s what I was hoping.

 

[conneryc]

Aerotech M1500G Grain Bonding question.....

I'm about to do my first grain bonding attempt and I just wanted some clarification on the grain spacer o-rings. I've seen some people say that they should NOT be greased and others say they should.

The grain bonding instructions that came with the motor show Step 5 "Install a grain spacer o-ring". No mention in those instructions for the o-rings to be greased or not.

However, in the RMS-75/1280-10240 Assembly Drawing and Instructions, Step 1 is "Lightly grease o-rings (4, 9, 13 & 14) where 14 is identified as "grain spacer o-rings"

So before I start, I just wanted to get clarification so that I have the best chance of success.

Thanks

 

[rfjustin]

Aerotech M1500G Grain Bonding question.....

I'm about to do my first grain bonding attempt and I just wanted some clarification on the grain spacer o-rings. I've seen some people say that they should NOT be greased and others say they should.

The grain bonding instructions that came with the motor show Step 5 "Install a grain spacer o-ring". No mention in those instructions for the o-rings to be greased or not.

However, in the RMS-75/1280-10240 Assembly Drawing and Instructions, Step 1 is "Lightly grease o-rings (4, 9, 13 & 14) where 14 is identified as "grain spacer o-rings"

So before I start, I just wanted to get clarification so that I have the best chance of success.

Thanks

Grain spacer o-rings do not need grease.

 

[eggplant]

No reason to grease them! The reason to grease other o-rings is to make the components they are installed into easier to slide into place, and to prevent damage during installation. Once the o-ring is in place, the grease doesn't do anything (for a static seal). Grain spacer o-rings are there to make sure that the faces of the grains are exposed and able to burn and aren't intended to seal anything. They just drop into place, so no grease is required.

 

[conneryc]

Wow! That was NOT a fun experience. I don't know if the bottle of Elmers Glue All that I got from Amazon was old or what, but it seemed to start foaming almost immediately. Made a mess and I was barely able to get the forth grain into the liner. I wrapped the seal disk and the nozzle in a couple wraps of saranwrap, made sure the bottom grain was in contact with the nozzle and that the nozzle shoulder was flush with the bottom of the liner. But some weight on top to keep it from expanding. There HAS to be an easier and less messy and stressful way to do grain bonding. I think part of the problem was because I had to peel off the glassine layer from the grains to get them to slide easily into the liner. Otherwise they were very tight and would only slide through with some effort.

 

[DAllen]

Wow! That was NOT a fun experience. I don't know if the bottle of Elmers Glue All that I got from Amazon was old or what, but it seemed to start foaming almost immediately. Made a mess and I was barely able to get the forth grain into the liner. I wrapped the seal disk and the nozzle in a couple wraps of saranwrap, made sure the bottom grain was in contact with the nozzle and that the nozzle shoulder was flush with the bottom of the liner. But some weight on top to keep it from expanding. There HAS to be an easier and less messy and stressful way to do grain bonding. I think part of the problem was because I had to peel off the glassine layer from the grains to get them to slide easily into the liner. Otherwise they were very tight and would only slide through with some effort.

To make the experience better I almost always peel some of the grains prior to gluing. Making sure to get enough off that they slide in/out of the liner without a lot of effort. Then getting a nice even (not thick) coat with the glue is easy peasy. Also, I don't know a lot about the Elmers glue but yeah, if its foaming right off the bat I would toss it and go to the local mom & pop hardware store to get the next bottle. I'd want stuff that is functioning correctly especially in this application.

 

[conneryc]

To make the experience better I almost always peel some of the grains prior to gluing. Making sure to get enough off that they slide in/out of the liner without a lot of effort. Then getting a nice even (not thick) coat with the glue is easy peasy. Also, I don't know a lot about the Elmers glue but yeah, if its foaming right off the bat I would toss it and go to the local mom & pop hardware store to get the next bottle. I'd want stuff that is functioning correctly especially in this application.

What glue do you use? I've seen some say to use Gorilla Glue, but I just went with what Aerotech recommends.