Help with by L1 flight: Aerotech RMS-29/360 and H180W-14A

[WizardOfBoz]

So I had heard that Aerotech engines were a bit complex in all their permutations. For example, this old thread highlights all the different sizes and spacers and such.

So I have the RMS-29/360, and an H180W-14A for my engine (what does the "A" stand for, btw?), and the "Reload Adapter System" (RAS).

The motor comes with the aluminum motor case, a standard motor forward closure, a forward seal disc, and a motor aft closure,

The RAS comes with two spacers, a floating forward closure, and a retaining ring.

For a normal 360 size motor one uses the forward seal disk (optional, depends on motor?) and the forward closure.

For a shorter motor (in my case, a "240"), one uses the floating forward closure instead of the standard one. So I'd put the delay charge (with appropriate o-ring) in the floating closure, and the ejection charge with cap on the forward end of that floating closure, then put it in the casing, then add the appropriate number (one or two) spacers, and then the floating forward closure. Is this correct?

The picture shows the aft closure, the casing, and the (optional) forward disk seal (the common parts) in the vertical middle of the picture, with the two foreward options above and below. Below is shown the standard aft closure for full 360 size motors. Above is the floating forward closure, two extensions, and the retaining ring. For my L1 motor (shown) the upper arrangment is what I want.

Aerotech's instructions were apparently written by engineers. As an engineer myself, let me clarify that is not a compliment. Why not show an exploded diagram in the instructions? Grrrr.

But to help ensure I don't CATO on my L1 flight, do I have the correct parts laid out?

Thanks!

 

[MarsLander]

This should help you...

 

[jmasterj]

It's looks like you have things laid out correctly. Make sure you contain the BP well; it can be tricky in the 29mm floating closure because there's not much room for tape between the outside of the closure and the inside of the spacer.

 

[WizardOfBoz]

Thanks, MarsLander. I think what I've got is correct. BTW, I have LocTite High Temperature Anti-Seize. Would this be better than SuperLube?

 

[jmasterj]

Thanks, MarsLander. I think what I've got is correct. BTW, I have LocTite High Temperature Anti-Seize. Would this be better than SuperLube?

Type of grease really doesn't matter much.

 

[WizardOfBoz]

It's looks like you have things laid out correctly. Make sure you contain the BP well; it can be tricky in the 29mm floating closure because there's not much room for tape between the outside of the closure and the inside of the spacer.

Yes this does look tricky, because there are two holes in the floating closure! Apparently one could plug the hold in the closure from the aft side, add the BP, put the cap on invert the closure, pull out the plug, and then put the closure into the casing with the aft side up. When the forward retainer is screwed in, one should be good to go.

 

[WizardOfBoz]

Type of grease really doesn't matter much.

Think I'll use superlube on the o-rings, and loctite* on the threads.

*Loctite antisieze, not loctite threadlocker!

 

[-Slick-Ice]

The super lube should be the NGLI-2 synthetic grease and can be used for the o-rings and threads.
I would not use what I am assuming is nickle anti-seize on the aluminum threads.

 

[troj]

Think I'll use superlube on the o-rings, and loctite* on the threads.

*Loctite antisieze, not loctite threadlocker!

Use the Superlube on the threads, as well.

 

[SolarYellow]

I would never use anti-seize on the threads of a case due to the mess the metal powders make. They will get everywhere.

Apart from Aeroshell 64 grease on an AR15 barrel nut, the only anti-seize I will use on aluminum threads is "ZDP," or zinc-dust petrolatum. It does the anti-seize job and the zinc actually inhibits corrosion of the aluminum. The metal powders (copper, nickel, etc.) in every other mixture sold as anti-seize that I have ever looked at will promote corrosion of aluminum.

SuperLube or any decent silicone-based (compatible with any o-ring) synthetic should work perfectly on the threads, and you'll only have one more tube of goo to carry around.

 

[bad_idea]

H180W-14A for my engine (what does the "A" stand for, btw?)

"A" indicates that the delay may be adjusted to be shorter by drilling. You can either drill it very carefully yourself according to the instructions, or you can use the RMS 18-38mm Delay Drilling Tool (RDDT) to make it simpler. Note there is a separate tool for 54mm RMS delays (54RDDT), and a third for disposable (DMS) motors (UDDT).

 

[jmasterj]

Yes this does look tricky, because there are two holes in the floating closure! Apparently one could plug the hold in the closure from the aft side, add the BP, put the cap on invert the closure, pull out the plug, and then put the closure into the casing with the aft side up. When the forward retainer is screwed in, one should be good to go.

I'm not clear what that means. You have it facing the right way in the picture. Assemble the delay into the closure, then add the BP to the well before you put it into the casing. Then fill any space in the week with wadding and tape over it securely. THEN assemble it into the case, put the spacers on top, and screw in the RAS forward closure.

 

[JackC]

Do NOT use Loc tite on your threads. Your closures should only be hand-tight. Do use your grease on the threads. The type of grease doesn’t matter much with small motors (H or I). Vasoline will work fine. I tend to use Superlube and that will work even better.

 

[speed]

Use the Superlube on the threads, as well.

Been doing that since 1993. Still have all my original cases. I use them and even loan them out! I have tubes that say "Archer" on them!

 

[WizardOfBoz]

Ok, the "optimizer" in me has been convinced: Superlube it is. I actually like SuperLube. It has Teflon(R) in it I think. I used to work where DuPont made Teflon(R). Thanks, all.

 

[wonderboy]

I have to post this... I'm sure anti-seize would work wonderfully to keep the threads lubricated and prevent galling but the big problem with it is illustrated in the following picture:

 

[troj]

So I had heard that Aerotech engines were a bit complex in all their permutations. For example, this old thread highlights all the different sizes and spacers and such.

One question that comes to mind, from reading this - have you ever sat down and watched someone assemble a 29mm or 38mm high power reload? If not, I'd suggest grabbing someone at your next launch, who's good at explaining things, and then watch them assemble a motor. It'll be time well spent.

From some of the questions you're asking, it feels like this is an area where you're a little uncomfortable. Having someone show you how it's done will help.

Then, ask your certifying authority (whomever is going to sign off on your cert) to watch you assemble the motor. They should be able to help answer questions, if you have any, as you go.

-Kevin

 

[WizardOfBoz]

troj (Kevin), thanks. I think I understand the logic and how it all works. But you're right, nothing wrong about asking for help.

And if you don't ask for help you miss out on hilarious posts like wonderboy's.

 

[JackC]

One question that comes to mind, from reading this - have you ever sat down and watched someone assemble a 29mm or 38mm high power reload? If not, I'd suggest grabbing someone at your next launch, who's good at explaining things, and then watch them assemble a motor. It'll be time well spent.

From some of the questions you're asking, it feels like this is an area where you're a little uncomfortable. Having someone show you how it's done will help.

Then, ask your certifying authority (whomever is going to sign off on your cert) to watch you assemble the motor. They should be able to help answer questions, if you have any, as you go.

-Kevin

You can probably find motor building on YouTube, too. It’s nice to have a video you can pause and rewind.

 

[WizardOfBoz]

Yes, there are ample resources on youtube and (for example) Apogee (thanks, Tim!) to allow one to grok the method and technique involved. At least I'm reasonably confident of getting the motor installed in the correct direction.