I'll fly the thing naked if it comes down to that.

Art won't let us fly naked. The rocket either. He considers it to be a "requirement". It would make the film look better.

Doug

... machined aluminum bulkheads and rings seem like the only way to go. ...

I'm a big believer in not combining dissimiler materials in assemblies wherever possible. Although attractive when 1st machined, Aluminum sheet is not as ideal (or as robust, in amateur rocketry applications as G10 FR4. first of all aluminum (.098 lg/in^3) weighs more than G10 (.065 lb/in^3) and yet has the same tensile strength, assuming one is using the higher grades of aluminum like 5052-H48 and 6061-T6, otherwise G10 is stronger. For avbay construction, the G10 provides electrical insulation and impact resistance over aluminum.

The biggest concern, I would think, especially when used as centering rings and bulkheads, is that the coefficient of expansion of aluminum is 13x10-6 in/in/DegF as compared with G10's 6x10-6 in/in/DegF or twice that of G10. A slip fit in the winter could become an interference fit in the summer, and any aluminum sheet bonded to FG could have the adhesive separate, which brings us to the next issue. Most of the time it probably wouldn't matter.

A bigger issue is that epoxy does not bond well with aluminum, which is why there is a whole family of fasteners available with large backing plates full of holes or other features that allow the resin to flow over many surfaces to make a better grip. I've never laid up FG before but have designed many products using it. The last point, is if you need to repair a bulkhead (like moving a hole from one spot to another), G10 is easier to play with, just fill the hole with epoxy and drill a new one.

My take, anyway. (aluminum fins mounted with fasteners excluded)

Damn I've been doing it wrong all this time 😯 Actually Mike, I don't glue in the aluminum bulkplates, they are bolted to the motor/booster etc.

Doug

This bird is all bolt-together except for tip to tip carbon and glass and some incidental epoxy to aluminum joints that have no structural ramifications. In that case though there are little machined grooves all around the ring designed to take the epoxy as well as a rather coarse machining so that the epoxy has something to bite.

Next bird down the pike for me will likely have no epoxy other than what is in the commercial airframe and nosecone and will use bolt on aluminum fins as well unless I get seduced by doing a 4" MD altitude bird.

Besides, I'm far more afraid of G10 and epoxy dust and breathing it than I am worried about aluminum, which fortunately comes off as rather coarse swarf rather than super-fine dust that floats in the air for hours.

Warren

Damn I've been doing it wrong all this time 😯 Actually Mike, I don't glue in the aluminum bulkplates, they are bolted to the motor/booster etc.

Doug

No wrong way in this hobby, just personal preference. 😉

I've got a TIG welder when anyone wants to start making really big aluminum launch vehicles. 😀 ...or small 6-32 eye-nuts 💡

No welded aluminum rockets, or in other words no rockets constructed primarily of metals at commercial launches. No reason to do that anyways, composites and other forms of construction are easily strong enough to meet the demands of a rocket, they also weigh a lot less.

Art

No welded aluminum rockets, or in other words no rockets constructed primarily of metals at commercial launches. No reason to do that anyways, composites and other forms of construction are easily strong enough to meet the demands of a rocket, they also weigh a lot less.

Art

Unless you are the BEE team....if you know what I mean!

While I don't care which I use, U-bolts got me my L3 flight safely and reliably, lifting eyes are actually stronger mechanically. Right ME's, Warren and Mike? But, when I venture to MD, I'll definitely use lifting eyes with a locking nut.

I've never once had an eyebolt even start to think about coming off. I do use lock washers, blue Loctite, and some serious elbow grease putting them on.

You know, JW, I rub my elbows on screw joints, but I never get any grease. What am I doing wrong? 😯

BTW, blue or red Locktite is good stuff! Used 'em both with success.

Blue is better for most uses. The red is ULTRA high strength and most times it takes the heat of a torch to get the joint apart. Blue has high strength but can still normally use hand tools with no heat to get them apart..

But your right Bruce GREAT STUFF!

No welded aluminum rockets, or in other words no rockets constructed primarily of metals at commercial launches. No reason to do that anyways, composites and other forms of construction are easily strong enough to meet the demands of a rocket, they also weigh a lot less.

Art

So what is this thing you call a commercial launch...? Think I heard the term long ago.. but just don't remember....

When I use locktite, I typically use the green because I generally do want the part to come apart eventually. Otherwise I use CA or epoxy.

I'm a bigger fan of U-bolts than eye-nuts personally. As I said in an earlier post, my L3 project is using eye-nuts and I'm drilling and pinning them so they don't un-thread.

I'm no ME Bruce - not event close. When it comes to mechanical things, I'm a seat of the pants kinda guy armed with a few rules of thumb. Electronics and software are a completely different thing and even that is becoming a thing of the past. IT is rotting my brain. I'm an EE with a CompSci minor who still kinda sorta remembers how to use a slide rule. I did learn Fortran using punch cards though back in 75.

Warren

When I use locktite, I typically use the green because I generally do want the part to come apart eventually. Otherwise I use CA or epoxy.

I sell TONS of loctite (Just about anything they make) There are 2 Main forms of green. One is a sleeve retainer like used for putting a cylinder sleeve in the engine of a car. The other green they make is a penetrating formula for all ready assembled parts. Its designed to go in and penetrate the threads and lock them tight. The Permatex Corp. makes a lot of stuff (Parent Company of Loctite products) There are some other formulas of green but(and blue and red) but all specific application materials. Like 3M, Permatex is a very large company.

I did learn Fortran using punch cards though back in 75.

I used Fortran IV back in 1970! Ever drop your cards? 🙄 I can get the blue apart, and I just use the red on joints I don't want coming apart. Guys, I'm not aware of the green... ❓

No welded aluminum rockets, or in other words no rockets constructed primarily of metals at commercial launches. No reason to do that anyways, composites and other forms of construction are easily strong enough to meet the demands of a rocket, they also weigh a lot less.

Art

Unless you are the BEE team....if you know what I mean!

Ha! That will never happen again, I mean BEE will never fly at our sites again as long as I am alive.

Art

No welded aluminum rockets, or in other words no rockets constructed primarily of metals at commercial launches. No reason to do that anyways, composites and other forms of construction are easily strong enough to meet the demands of a rocket, they also weigh a lot less.

Art

Unless you are the BEE team....if you know what I mean!

Ha! That will never happen again, I mean BEE will never fly at our sites again as long as I am alive.

Art

THUG SMASH!