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crossfire

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I disassembled the motor and grabbed a few pictures. The first shows how far into the liner the nozzle will seat, when the forward seal disk is installed. The other two show the length of the liner.

It does look like the liner is somewhere around .1" or .15" shorter than specified on the assembly drawing. Worst case, I'll take the liner from another reload for the flight next weekend.
How about cutting a little off 1 grain?
 

neil_w

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Any timetable update on the 24mm Q-jets?
I'd like to follow up on my own question with another.

[Edit: sorry my whole premise is wrong; I didn't realize these came in -10 options as well since all my rockets are comfortably in the 4-7 range. So I guess 4/7/10 makes sense, although I still think 5/7/10 would likely be more useful]

I've added the D22 and E26 to all my sims. The vast majority of them show ideal delays in the 5-7s range, with most in the 5-6 second range (especially the D22). That puts them frustratingly in the middle between the available delays of 4-7 seconds. Obviously I will tune this when I get a chance to launch with them, but at the start I'm stuck with choosing a very early or very late delay.

With Estes motors or the 18mm Q-jets I can always find a good enough delay, given the 3/5/7 or 4/6/8 options. But it looks like I might have a struggle with many of my rockets with the 24mm Q-jets. So I am wondering if you could comment why -4 and -7 were chosen as the only delay options.

I will note that I have similar problems with some of the 24mm single-use motors, but my impression is that the Q-jets are intended for more mass-market use, where more options would be desirable.
 
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kevin.mcgee

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I tried to assemble a 54mm motor at Red Glare 2021. It was a J415R. The rear nozzle would not fit into the liner at all. I tried to shave down the inner edge of the liner. When I seated the nozzle I used too much force and the o-ring was compressed until it bulged. Then I couldn’t get the grains, liner, nozzle, and o-ring into the case. I probably should have taken the whole thing home and done the repairs on my workbench rather than in the field. $85 wasted.
 

3stoogesrocketry

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I tried to assemble a 54mm motor at Red Glare 2021. It was a J415R. The rear nozzle would not fit into the liner at all. I tried to shave down the inner edge of the liner. When I seated the nozzle I used too much force and the o-ring was compressed until it bulged. Then I couldn’t get the grains, liner, nozzle, and o-ring into the case. I probably should have taken the whole thing home and done the repairs on my workbench rather than in the field. $85 wasted.

Wasted ? Why can you not make it work? Did you ask any other seasoned fliers or any of the very fine vendor that attended?
 

jd2cylman

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I’ve never been able to get that o-ring in. I leave it out and use a seal disc with a o-ring on the front end instead. Any bulge at all and that o-ring won’t go in. I think the o-ring they use is one size too big.
 

Rocketjunkie

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If ypor 54 mm reload came with a flat phenolic washer then the thin o-ring goes around the nozzle shoulder. If no phenolic washer, the reload uses the seal disk and the o-ring goes in the seal disk groove. The seal disk is thicker than the phenolic washer and there is NO o-ring around the nozzle shoulder. If the nozzle does not easily fit then sand out the end of the liner until it does. Make sure there are no burrs where the liner was cut to length.
 

jd2cylman

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It’s working for me. I’m not gonna wrestle with it when I have a lot of extra forward seal disc o-rings. Everything still fits fine.
 

crossfire

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It’s working for me. I’m not gonna wrestle with it when I have a lot of extra forward seal disc o-rings. Everything still fits fine.
Your saying on some reloads a seal disk goes on nozzle end and forward closure end?
 

AeroTech

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I tried to assemble a 54mm motor at Red Glare 2021. It was a J415R. The rear nozzle would not fit into the liner at all. I tried to shave down the inner edge of the liner. When I seated the nozzle I used too much force and the o-ring was compressed until it bulged. Then I couldn’t get the grains, liner, nozzle, and o-ring into the case. I probably should have taken the whole thing home and done the repairs on my workbench rather than in the field. $85 wasted.
We were at Red Glare 2021. You can always ask us or any dealer to help you.
 

AeroTech

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I disassembled the motor and grabbed a few pictures. The first shows how far into the liner the nozzle will seat, when the forward seal disk is installed. The other two show the length of the liner.

It does look like the liner is somewhere around .1" or .15" shorter than specified on the assembly drawing. Worst case, I'll take the liner from another reload for the flight next weekend.
Strange. Please contact Karl at warranty@aerotech-rocketry.com
 

KenECoyote

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(Note: cross-posted)
Hi, apologies if this is a silly question since I've only just returned to the hobby after years away...
When assembling my 29mm reloads (one 40-120 and the other 180-240 both are new old stock), I noticed that the delay or delay spacer sits proud out of the forward closure (based on the 40-120 instructions it's supposed to)...this means there is a space between the fwd closure and the forward insulator/seal disk and the forward o-ring can be loose...unless the center of the seal disk flexes in towards the grain?

IMG_20210411_214522506.jpg
IMG_20210411_155219447.jpg
Of note is that in the past I probably have assembled dozens of reloads, never had any failures and just now noticing/realizing this.
Edit: Is the o-ring held in place by the pressure of the motor burning and more to prevent gas from escaping the sides of the fwd closure?
 
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Reinhard

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(Note: cross-posted)
Hi, apologies if this is a silly question since I've only just returned to the hobby after years away...
When assembling my 29mm reloads (one 40-120 and the other 180-240 both are new old stock), I noticed that the delay or delay spacer sits proud out of the forward closure (based on the 40-120 instructions it's supposed to)...this means there is a space between the fwd closure and the forward insulator/seal disk and the forward o-ring can be loose...unless the center of the seal disk flexes in towards the grain?

View attachment 459550
View attachment 459551
Of note is that in the past I probably have assembled dozens of reloads, never had any failures and just now noticing/realizing this.
Edit: Is the o-ring held in place by the pressure of the motor burning and more to prevent gas from escaping the sides of the fwd closure?
On the RMS 29/40-120, the delay o-ring gets compressed during tightening of the closures:

On the RMS 29 high power style casings, this is not the case:

Reinhard
 

AeroTech

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The Model Rocket Industry and Hobby Rocketry Loses a Pioneer and Icon

Paul C. Hans passed away early Friday morning, April 9th, 2021 at the age of 74. Paul, along with Don Scott, were the first rocketeers to launch an 8mm movie camera in a model rocket in 1962 in Port Washington, NY. Later that year, they did it again at NARAM-4 at the United States Air Force Academy in Colorado Springs, CO, where they also made the very first egg loft flight with their movie camera rocket.

Paul became a behind-the-scenes icon in the model rocket industry and hobby rocketry with his investment in Enertek™ in 1987, which together with co-owners Lee Piester and Gary Rosenfield, created the first full-line mid-power rocket company since the demise of Enerjet™ in 1974. At the 1987 HIA Trade Show in St. Louis, MO, Enertek experienced instant success and demand for its exciting mid-power hobby rocket line, supported by beautiful packaging and aerospace-grade engineering and composite propellant technology. Unfortunately, due to the inability to raise additional capital to meet the initial demand, Enertek was forced into a voluntary liquidation. Paul acquired the physical and intellectual assets of Enertek, and along with additional personal funding rolled them into an investment in Industrial Solid Propulsion™ (ISP™), Inc., owned by Gary Rosenfield and Dan Meyer. Gary Rosenfield’s AeroTech proprietorship was converted to a corporation and simultaneously became a subsidiary of ISP. Up to that point AeroTech had only been involved in composite propellant motor production, but Paul’s significant financial spark allowed Gary and Dan to accelerate AeroTech’s growth and prominence in hobby rocketry, thanks to the acquisition of the Enertek assets and Paul’s other contributions.

Paul was a co-inventor on the Copperhead™ igniter, Fin-Lok™ plastic fin assembly, Labyrinth™ ejection system and RMS™ (Reloadable Motor System) reloadable motor patents. He also designed the Copperhead™ igniter clip, Interlock™ launch controller, Wart-Hog™ mid-power rocket kit, and wrote most of the original instructions for AeroTech’s rocket kits and ground support equipment. He became a major influence in the strategic direction and legal and regulatory matters of the business. Paul sold his ownership in ISP to the RocketAdventure partnership in 1999, but continued his involvement with the company as a trusted and experienced advisor and consultant over the years, literally until his last day.

Paul attended Brown University in RI and earned an MBA from the Wharton Business School in PA. He spent many years in the field of mergers and acquisitions, which included runs with General Dynamics and Fairchild Industries. He became an expert in aerospace industry business management, strategic planning and financial analysis. Even with the demands of his job, which included extensive travel both domestically and abroad, he raised 3 incredibly talented, worldly and successful children who have told us first hand that, “Dad was always there to support us in everything we did growing up, which continued into adulthood as our most valued advisor.” All three children have precious memories of their model rocketry experiences with Paul as a young father.

Paul had been battling a severe cancer for about two years and was surrounded by his loving family, longtime girlfriend and close friends when he passed. Gary Rosenfield, Karl Baumann and Dane Boles were honored to be with Paul on Thursday and Friday to thank him for all he had done and to say goodbye.

The management team and employees at AeroTech/Quest/RCS were blessed and honored to have enjoyed Paul’s years of hands-on support, counsel, guidance and advice. We will continue to move forward with Paul’s favorite saying in mind, “Steady as she goes!”.
IMG_5552.jpeg

Paul and Jesse.jpeg
 

KenECoyote

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Thanks Reinhard! That was the key point...I didn't think the delay o-ring would compress 1/16", but just tested it and it does for the RMS 29/40-120. However if that is not the case for the RMS 29 high power, I am surprised the spacer sits even higher (about 1/8"). However cranking down on the assembly seems to crush it a bit and also compress the delay o-ring, so for mine it behaves same as the 29/40-120.

I appreciate the response and information since uncertainty on a reload is never a good thing!
 

AeroTech

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Thanks Reinhard! That was the key point...I didn't think the delay o-ring would compress 1/16", but just tested it and it does for the RMS 29/40-120. However if that is not the case for the RMS 29 high power, I am surprised the spacer sits even higher (about 1/8"). However cranking down on the assembly seems to crush it a bit and also compress the delay o-ring, so for mine it behaves same as the 29/40-120.

I appreciate the response and information since uncertainty on a reload is never a good thing!
On the high power hardware, the spacer should not protrude beyond the delay insulator by more than about 1/32”.
 

KenECoyote

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Im extremely unclear of what we are looking at?
Here's a pic of the same disassembled.
IMG_20210411_181833667.jpg

Top row all except the right most item is what was in the previous pic.
Bottom has casing and standard forward closure.
 
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