AeroTech Open Thread

[mikec]

I'm not a glider person, nor Aerotech, but couldn't you just put the delay grain in, and then put no powder in the ejection charge well?

If all you're trying to do is not get an ejection charge, then certainly. If you are trying to use an RC (glider) 24mm reload with a standard 24mm case, you can't. Even plugging the forward closure with JB Weld, the 24mm RC reloads don't seal correctly.

Maybe the OP could clarify what they are trying to do.

 

[kjohnson]

If all you're trying to do is not get an ejection charge, then certainly. If you are trying to use an RC (glider) 24mm reload with a standard 24mm case, you can't. Even plugging the forward closure with JB Weld, the 24mm RC reloads don't seal correctly.

Maybe the OP could clarify what they are trying to do.

All I'm trying to do is find out if AT is considering making a plugged forward closure for the 24mm reload casing, like they did for the 18mm casing. Or if not, will AT provide a manufacturer's recommendation to plug the 24mm forward closure like they did with the 18mm casing.

Try not to read too much into a simple question, and while I appreciate ingenuity that folks approach a problem (especially the epoxy in the delay insulator - that's pretty slick), I'm really interested in the AT response.

Thanks,

kj

 

[burkefj]

Yes please, those of you suggesting plugging or using JB weld do not understand the dimensions internally of the 24mm standard case and the RC reloads. There is a lip on the forward closure for the o-ring that exists in standard reloads that does not exist in the rc reloads, that lip allows the liner to push forward when using an RC reload and not seal the rear o-ring correctly so filling with JB will not work by itself. All it needs is to have a .03 fiber washer included in the reload to butt against the forward closure lip and the endburning reloads will work fine, I've flown them myself this way. I've talked to Charlie about this. I've also asked him about a plugged closure and reducing prices on the rc cases. He seemed interested.

Frank

 

[Estesbasher]

KJ. Whats wrong with using the delay? Just buy them with the short delay and leave out the powder. You can give them a call or ask them on face book. The link in on the front page.https://www.aerotech-rocketry.com/ I thought you where just using the regular 24/40 case and reloads for your gliders

 

[burkefj]

There is no delay in 24mm RC reloads, there is propellent, one o-ring and a nozzle....that's it.

KJ. Whats wrong with using the delay? Just buy them with the short delay and leave out the powder. You can give them a call or ask them on face book. The link in on the front page.https://www.aerotech-rocketry.com/ I thought you where just using the regular 24/40 case and reloads for your gliders

 

[mwtoelle]

There is no delay in 24mm RC reloads, there is propellent, one o-ring and a nozzle....that's it.

I will also mention that the RMS-24/40 RC and the RMS-32/60-100 RC reload cases have only a rear closure. The case is machine from a block of aluminum, which is the reason that they cost so much. The only RC reload with a delay element would be the F23 Skywriter reload for the 32mm case, the load has an 8 second smoke trail for leaving trail while doing aerobatics after lift off. It has a plastic holder for the the smoke column.

 

[kjohnson]

KJ. Whats wrong with using the delay? Just buy them with the short delay and leave out the powder. You can give them a call or ask them on face book. The link in on the front page.https://www.aerotech-rocketry.com/ I thought you where just using the regular 24/40 case and reloads for your gliders

I use the RC casing for my gliders. Have plenty of them, they work great. The question isn't about gliders though. I know I used the example of the C3.4 and D2.3 and called them glider motors but that's cause I couldn't remember the designations 😱

I brought them up because it's the only time I've seen AT say this:
"AeroTech designed the new end-burning reloads to be compatible with existing RMS-18/20 hardware. Users are instructed to plug the ejection well in the forward closure with “JB Weld” epoxy to prevent reverse thrust from escaping out the forward end of the motor as the propellant grain burns out. AeroTech will make a separate forward closure available for users who wish to continue using their RMS-18/20 motors with standard model rockets, and there are also plans for a “plugged” forward closure to eliminate the step of applying the JB Weld epoxy." (Source- https://www.oldrocketforum.com/showthread.php?t=12809 )

Just wondering if a plugged forward closure for the 24mm case is being thought about and if not, would AT recommend the same JB Weld instructions for the 24mm casing.

kj

 

[emckee]

New question/request for Aerotech:

Please update the instructions for the L850 reloads... I flew one of these last weekend, but ran into a hiccup when assembling the motor. The instructions call for a fiber washer as the forward insulator, but one is not included in the reload kit. Also, a third O-ring is included, but is not mentioned in the instructions. Through a fair amount of head-scratching and consulting with more knowledgeable folk, we put it on a seal disk and assembled the motor as such, but this being my first 75mm motor build, I was very nervous deviating from the instruction set, as you might imagine.

The flight went beautifully, btw...

Thanks!
-e

 

[ATGM]

Did I read that right? Is there a "possibility" of a 29mm Super Thunder?

Yes, we are filling in the 29mm HP line with some ST and some DM.

 

[ATGM]

I'm trying to simulate flying a M1297 in a 75/6400 case. Can someone tell me how much a 75mm spacer and one grain worth of case weigh? I seem to recall that CTI stated 400g for each spacer and case length that you add.

Chris,

If you don't have that info yet please email Karl and see if he can get that for you. Inbox me if you need his contact info. Thanks!

 

[ATGM]

Noted! Thanks for the clarification...

Now, what can you tell us about the new reloads?

-e

We have the 24/60 blue and red almost wrapped up and also are working on some 29/40-120 red and sparky loads. A bunch of other stuff but those are the main ones at this time.

 

[ATGM]

View attachment 295140View attachment 295141:

Charlie,

Saturday I launched a 75mm L1040DM, AT/CTI crossload for the first time. It was a spectacular take-off lot's a, fire, smoke, sparks and loud noise...

The motor assembly was simpler than I expected, one less O-ring than the CTI reload. The YouTube video is excellent, https://www.youtube.com/watch?v=d0xjmJ-Yur8&feature=youtu.be,
and it should be linked to the AT online instructions.

Less expensive hardware and less expensive reloads, it couldn't be better...:wave:

Thanks,
Spicer

Awesome Spicer, thanks for showing that!

 

[ATGM]

Is there any chance that Aerotech will make available a plugged forward closure for the 24mm casing, like they did for the 18mm casing? Or if not, provide guidance on plugging ejection well of the 24mm casing like they did for the 18mm casing when the C & D glider loads were released?

Thanks,
kj

I will respond to this question with an answer that more broadly covers the subject of Hobby hardware in general; we are currently updating the hardware and that includes things like the 24mm plugged closure but most notably you will see some pricing adjustments made in the favor of the consumer. Look for AT to get the hobby hardware pricing down in the next 45-60 days.

 

[ATGM]

New question/request for Aerotech:

Please update the instructions for the L850 reloads... I flew one of these last weekend, but ran into a hiccup when assembling the motor. The instructions call for a fiber washer as the forward insulator, but one is not included in the reload kit. Also, a third O-ring is included, but is not mentioned in the instructions. Through a fair amount of head-scratching and consulting with more knowledgeable folk, we put it on a seal disk and assembled the motor as such, but this being my first 75mm motor build, I was very nervous deviating from the instruction set, as you might imagine.

The flight went beautifully, btw...

Thanks!
-e

All 75mm instructions are being updated and will be as simple as the 38mm RMS-PLUS instructions. These are almost finished, they are awesome and super easy to follow. There will only need to be 2 versions for all of the 75mm loads so it will be much easier next time around.

 

[markg]

Yes, we are filling in the 29mm HP line with some ST and some DM.

29 DM - yes please!

 

[djs]

working on some 29/40-120 red and sparky loads

Any idea on the timeframe for these? I'm excited for both!

 

[emckee]

We have the 24/60 blue and red almost wrapped up and also are working on some 29/40-120 red and sparky loads. A bunch of other stuff but those are the main ones at this time.

Ooooh, I've been waiting for the return of the 29/40-120 red load for quite a while, glad to hear it's on the way. And DM too!!! Woohoo!

waiting with baited breath...

 

[tab28682]

....

Just wondering if a plugged forward closure for the 24mm case is being thought about and if not, would AT recommend the same JB Weld instructions for the 24mm casing.

kj

Before the RMS RC 24mm cases came out, I flew a number of the normal 24 mm RMS reloads (E18s and such) in my venerable Estes Stratoblaster. Simply packed the ejection charge area tightly with dog barf and taped it closed with several layers of masking tape. Worked fine and is less "permanent" than the JB Weld option.

Back in the day I would fly the case in a rocket glider and then in a normal rocket with motor ejection on the same day.

Having said all that, I would probably go ahead and buy a plugged forward closure for my 24mm hardware if it does become available.

 

[KenRico]

29 DM - yes please!

Perfect for a NytFlyr payload !

Kenny

 

[grouch]

Yes, we are filling in the 29mm HP line with some ST and some DM.

SCORE! Thanks Charlie. This is very good news. I can't wait to burn some 29mm ST in my small stuff. Very happy camper!

 

[Donaldsrockets]

We have the 24/60 blue and red almost wrapped up and also are working on some 29/40-120 red and sparky loads. A bunch of other stuff but those are the main ones at this time.

What are the rough designations of these loads???

I'd say anything in the average 40-80 N/s range should be awesome.

 

[Wayco]

Yes, we are filling in the 29mm HP line with some ST and some DM.

We have the 24/60 blue and red almost wrapped up and also are working on some 29/40-120 red and sparky loads. A bunch of other stuff but those are the main ones at this time.

This is great news for me, I have a dual deploy Argent that I have been feeding the single use H115 DM to for a while, it would be nice to have a cheaper reload for it. My D region Tomahawk flies well on the 24/60 F35, having some more choices for that casing would be great!

 

[markg]

Yes, we are filling in the 29mm HP line with some ST and some DM.

Also - how about getting DM available for sale in Canada?

 

[ATGM]

Also - how about getting DM available for sale in Canada?

We are currently working on getting DM approved for sale in Canada, we should know something soon.

 

[ATGM]

CTI 75mm Reloads Used in AeroTech Hardware Advisory

6/28/16



Dear AeroTech/RCS Dealers and Customers,


We have become aware of a problem that has occurred when customers use Cesaroni
Technologies (CTI) 75mm rocket motor reload kits loaded in AeroTech RMS hardware. There
have been a number of instances in which the motor casing gets very hot near the forward end
of the casing (immediately below the forward bulkhead), and in some instances a blister
develops on the casing. In most situations this renders the casing unusable for future flights.
This problem is caused by hot gases passing between the casing and the liner at the forward
bulkhead end, which occurs in the moments following ignition of the motor. In most rocket
motors, especially those with long L/D ratios, there is a significant difference in the internal
pressure of the motor between the aft and forward ends, due to the velocity of the gases in the
motor being higher at the nozzle end. This pressure differential allows a small amount of gas to
travel around the outside of the liner, through the liner/nozzle joint and out the nozzle throat.
AeroTech recognized this phenomenon many years ago and implemented a “forward seal disk”
(FSD) in its longer L/D motors (and exclusively in the 75 & 98mm RMS motors). The FSD
effectively seals the joint between the case and the liner, preventing any gas from escaping
through the gap. Unfortunately, CTI motors are not designed to be truly sealed at the
liner/casing interface and only have a phenolic washer captured between the liner and the
forward bulkhead in an interference fit. This arrangement does not provide a complete seal and
will occasionally allow enough gases to pass around the liner and cause a hot spot, casing
blister or in worst cases, a burn-through.


Therefore, customers who choose to use CTI reloads in AeroTech RMS hardware are advised
to include AeroTech’s forward seal disk and forward seal disk O-ring when assembling their
motors. This will minimize the case blistering problem. As an added bonus, it makes the motor
hardware far easier to clean up after recovery.


NOTE: AeroTech/RCS does not recommend the use of CTI reloads in AeroTech RMS hardware
and cannot warranty any resulting motor failures from this combination. Customers who seek
warranty repair or replacement under these circumstances are advised to contact CTI directly.
Your understanding and patience is appreciated, and we thank you for your continued support.

 

[iter]

I bought an I140 on Friday and found a new part in it, a metal washer. Updated paper instructions in the package refer to it as "ejection charge baffle washer." I don't use motor ejection on these, but I'm curious about this innovation. What does it do? What problem does it solve?

Ari.

 

[pyrobob]

I believe this was primarily the result of some of the larger throat motors such as the I205W and I500T having a weaker ejection charge at times. The washer chokes the ejection charge gas from going aft and "leaking" through the nozzle. I guess they adopted it to the entire DMS line.

 

[bob jablonski]

I believe this was primarily the result of some of the larger throat motors such as the I205W and I500T having a weaker ejection charge at times. The washer chokes the ejection charge gas from going aft and "leaking" through the nozzle. I guess they adopted it to the entire DMS line.

My understanding was due to a couple early ejections at or around burn out to prevent the flame from getting around the delay and setting off the ejection charge. I have seen a couple of these happen. And this is the reason Karl gave one of the flyers with the early ejection. You know it may actually be a preventitive measure on both.

 

[Kruegon]

At NSL 2016, Charlie was talking about the new part. It's designed to strengthen the ejection charge. Since I haven't dealt with the issue myself, I cannot speak on the actual effect. Just relaying the info I gleaned.

 

[tbonerocketeer]

My understanding was due to a couple early ejections at or around burn out to prevent the flame from getting around the delay and setting off the ejection charge. I have seen a couple of these happen. And this is the reason Karl gave one of the flyers with the early ejection. You know it may actually be a preventitive measure on both.

It chokes the hole into the closure so the ejection gasses go up, and not out the nozzle. A washer won't stop flame from bypassing anything.