Instead of borrowing a casing couldn't you use a 4inch coupler?

Yes, but 98mm is slightly smaller in diameter (3.86"), so a--wait, I'll measure one I have (I hope) in the garage, might be close. I was thinking about rolling up stiff paper to make a 98mm roll. Either thanks for the suggestion!

You nailed it! I'll have to sand it slightly, but it'll be a good tight fit and give a perfect centering for the retainer. Case closed! Thank you!

I think you need to have a motor case to properly fit the retainer. The aft closure on the Aerotech 98mm case has a different spacing than an AMW 98mm case than a Loki 98mm case than a Cesaroni 98mm case... You want to use the one with the largest spacing to ensure you can fit all the other casings... a little play at the ass end doesn't hurt.

Warren

Good advice. But I think the casing is just used to center the retainer. It should already have enough play. I think I better do one of Denverdoc's pearls of wisdom and re-read the instructions. Again, haven't drilled any holes yet, just checking with everyone to get an idea of what they've done. And, when the instructions say, "Use the motor casing..." they usually mean it. 🙂

Ok as that I have done this part and the use of a case is preferred but a piece of tubing would work. For the large 98mm threaded(or any of the Aeropac threaded retainers that bolt down like the 98mm) its not about the spacing because the actual part that mounts to the rocket does not do so by JB weld or mounting to the motor tube. It does so by being screwed down to the rearmost centering ring. there for the spacing difference in thickness of the motors does not matter as this style of retainer is compatible with all. (AMW,AT,CTI, Loki and some or most hybrids) all the motor casing or tubing does is help align the base that mounts to the centering ring so its centered corectly and not off center and so that the motor will be supported by the actual tube of the motor mount. So yes you could do this with nothing more then a piece of coupler for a 4" tube and use some masking tape to hold it in tight and stuff. I love these retainers over any of the slimlines because the are the industry standard and will mount just about any engine there is and retain it tight. The threads that are there when you spin them on make up the difference for different height spacings for the different motors. Not a fixed in place snap ring.

That's what I thought. You da man, Conway. Thanks!

Conway's advice is all perfect, however he left one thing out. Take it from me, I have lined up and mounted five 98mm AeroPack retainers so far and every one of them has lined up and every screw has fit just right. What Conway forgot to say was; be patient, you will soon find out what I mean.

Also, the reason that I love the larger screw/insert installed AeroPack retainers other than the fact that they are all compatible with every motor case in the industry is that I can remove them. You can do it either way, I know that some people like to mount a few screws and the permanently epoxy the retainer in place while others drill every hole and run wood screws into the back of the rocket which also permanently fixes the retainer to the aft end of the rocket.

Personally I have mounted every one of the retainers I have installed using the inserts and I have set it up so that I can simply remove all twelve screws from the retainer and remove the whole retainer assembly while the inserts remain. The reason I like to be able to remove the whole retainer after a flight is because the bigger motors tend to be very harsh on the back of the rocket and it is nice to be able to clean the retainer when it is standing alone, free from the rocket. I mainly did it in this way in case the rocket ever had a very hard landing and destroyed the retainer and threaded cap or damaged the large threads. In that situation I would be able to remove the retainer and replace it (unlikely, but I have seen rocks out there and don't tell me that in that huge area your rocket can only land in the soft grass, my L3 went 12,300 feet at the north site and out of all that area it touched down on the barbed wire fence, yah)

The lesson here today is that it doesn't hurt to plan for the future. Thanks for your time and good luck Bruce, let me know if I can help in any way! I signed off on your 1 and 2, I would love to be able to sign off on your 3.

Art

Thanks, Art. I wondered about that, permanently mounting the retainer ring. It IS designed to be removed, if you want. And, that's the way I'll go. All it has to do is hold the casing in, without the added push of an ejection charge. There are more than enough screws to do that without epoxy or JB Weld. Art, I'll bring it to Oktoberfest, and I'd like you to take a look at it. I'll have the fins glassed by Thursday night. Next is the ebay at the top of the booster. I'll cut a hatch, etc. At that point, I don't know where I want to have it separate. At first, I wanted the chute to be in above the booster and come out of the parachute tube above the booster, but that will leave the harness free to bang on the upper tube. If I separate at the booster, then there will be "no" chance of breaking the fiberglass tube above. Then again, I have a payload section that I want to hang free above the tube above the booster. At this point, I'll construct with all options possible. But I'm going to stop at that point and think about what I really want to do. Thanks, Art.

Bruce, if I may jump in at this point. I am in the design of my Level 3 also. What is the best way to deploy? Is it better to have the booster on its own recovery, and bring down the front half on its own? Or do you keep them together on a long shockcord? And what about a deployment bag? Art, Con, John S. and anyone elce, you guys see and fly the big boys alot, we could you your thoughts. 8)

Personally, I'm not separating anything! 🙂 I want it all to come down together, so I can find it. 🙂 Tim's L3 is going to be really spectacular, BTW. Tim, we should probably start an L3 topic thread somewhere. I'll copy part of your post and start it in "Construction."

Bruce, if I may jump in at this point. I am in the design of my Level 3 also. What is the best way to deploy? Is it better to have the booster on its own recovery, and bring down the front half on its own? Or do you keep them together on a long shockcord? And what about a deployment bag? Art, Con, John S. and anyone elce, you guys see and fly the big boys alot, we could you your thoughts. 8)

I would recomend to keep them together. Even on rockets the size of event horizon its not hard. Just have to build the recovery set up for that weight. Like in mine being at 55lbs 6" diameter 14ft tall. I will be using 1/2 inch tubular Kevlar harnes. Im doing typical Zipperles deployment. At apogee I will deply my Tac series 3ft chute on a 35 ft long harness between the booster section and the mid airframe. Then the mains deploy via the nose cone exit stage left and anothe 35 feet of 1/2 inch tubular kevlar harness. With a Rocket Rage chute bring it down safely at about 12 to 15 feet per second.

Now You can bring 2 sections down indepedantly but for my likes I think thats another potential for problems (unless we are taking like a rocket weighing in at 500 lbs then thats pretty well what you would have to do) Also Im not sure what you expect for Altitude. In my case I will be 13 to 14K in altitude with the power of the AMW N2020 White Wolf. SO It needs to be dual deploy so it doesnt drift out of the waivers 1 mile radius. As well as it would be yuky to walk that far and have to pack some 55lb brute over my shoulder all the way back. Deployment bags.. Ive never used them I did order a Tac Bag fromGLR.. and to be honest I will probably not use it. Kinda had issues with it myself. So I will just use a great big chute protector and wrap the chute like I do and make kind of a piston out of it.
But thats what I would do as well as what I will be doing.. Look forward to seeing the project!!!Let me know if anyone needs some help in signing off as a wittness or anything as I will be glad to help.

Conway

I am in the design of my Level 3 also. What is the best way to deploy? Is it better to have the booster on its own recovery, and bring down the front half on its own? Or do you keep them together on a long shockcord? And what about a deployment bag?

You know what they say about opinions... I prefer to separate my pieces. Only with a few exceptions, BDCR being one of them, I prefer my payload section to be separate from the rocket. My thinking is that I don't want them to be possibly banging into each other and I can go with two smaller chutes than one larger one, hopefully greater chance for deployment.

As far as them separating on recovery, if they have nearly the same descent rate, they do land close to each other. Like I mentioned BDCR was an exception because its "payload" was very lightweight I do keep it with the rocket. For my next project, I will likely go back to using different chutes for the payload section and booster.

Well, I took my time drilling the holes nicely and neatly, but when it came time to screw the threaded inserts into the G10 bulkplate, uh, they shredded. Nothing in the instructions say the Aero Pack 98mm retainer can't be set into G10. I wrote them for more threaded inserts, and I guess I'll make the 15/64 holes slightly larger, and epoxy them in. Any suggestions? Hate it when this happens. 🙂 Unless, of course, they're supposed to do that. The screw thread is really embedded into the G10 plate. Hmmm... 😳