20+ year-old Level 2 rocket, updated for fist flight...

[Mugs914]

Yep, it is over 20 years old and has never flown.

When I became a BAR in '95 or so, I quickly decided that HP was where I wanted to be and started working my way toward my Level 1 cert. Our local club was great, but our monthly launches were A - G only. There were HP launches a few times a year, but they were about three hours away and always seemed to fall on weekends I was out of town. I had a Vaughn Brothers Javelin (Still do. One f my favorite flyers!) that had many flights on F and G motors and I was going to use that for my l1. So I designed and built this rocket for my eventual L2 cert attempt.

Well, life intervened as it often does and between things like my business running me ragged, travelling frequently, moving, family issues and so on, my L1 cert didn't happen until a few weeks ago. Naturally. I started thinking about L2, and though I'm not in a rush, I am going to get the old bird ready to go. This will mostly involve a few mods to bring it up to date technologically (Things have changed a little bit in twenty years), so I thought I would start a thread to show the process and get yall's input. I hope you'll feel free with your comments and suggestions!

Here it is in all it's 21 year old glory:

 

[mbeels]

Following! I'm so used to having computer simulations for designing rockets. Did such things exist in '95? What tools did you use to design this rocket?

 

[Nick Hutton]

Awesome. How did you manage to keep it in such good condition with 20 years of storage. My kids would have trashed it long before now.

 

[Ben Martin]

Your rocket aged like fine wine. Can't wait to see it fly, keep us updated!

 

[Theory]

Very cool!

 

[Wayco]

I hope you are not planning to repaint it, that paint job is quite unique.
What size MMT does it have?

 

[Mugs914]

Following! I'm so used to having computer simulations for designing rockets. Did such things exist in '95? What tools did you use to design this rocket?

No. No computers were used (or harmed) in the making of this rocket. Back then I used a graph pad, pencil, various engineers scales (rulers), calipers, a calculator, the Barrowman equations and the Giant Leap rocketry catalog! That, help from knowledgeable friends and a bit of common sense would get you where you though you should be. Then you flew the thing to see if you got it right! Things are a lot easier now with OR, but I still like to work out my initial designs on paper.

Awesome. How did you manage to keep it in such good condition with 20 years of storage. My kids would have trashed it long before now.

Oh, it has it's share of hangar rash, but it had a place of honor in the corner of my rocket room where it was mostly out of the danger zone. Having no kids around helped too...

I hope you are not planning to repaint it, that paint job is quite unique.
What size MMT does it have?

Thanks! No, no repaint planned. That kind of pseudo-scale theme is the sort of paint job I still like to do on most of my rockets. I keep thinking I'll do something different, but never seem to.

This one has a 38mm mount. I'm not sure why I didn't go with a 54mm, must have had some reason that seemed logical at the time...

 

[Mugs914]

The biggest mod that I wanted to make was to update the method of recovery. Back then the coupler-type av bays weren't very common (at least as far as I knew). Dual deploy was accomplished using two separate payload bays stacked on top of each other. The middle one housed whatever electronics you were using and the top housed the main. This one was built that way and I wanted to convert it to use a coupler type av bay.

I didn't want to just build a new forward end for the thing, or change the paint job at all. Maybe I'm just sentimental, but after waiting for so long I wanted it to fly as it was built, at least externally. The coupler in the middle (electronics) payload bay was epoxied in with a vengeance, so removing the coupler to make way for a modern av bay wasn't an option. I could Dremel out the coupler bulkhead though.

After two hours of dremeling I had gone from this:



To this:



And, I had discovered three things: One was that Giant Leap sells some VERY stout plywood bulkheads. Number two was that my epoxy skills were quite advanced, even back then. The third was how very glad I was that I hadn't tried to dremel out the whole coupler!

More to come...

 

[Nytrunner]

That was some good dremeling!

 

[mbeels]

Yes, seriously impressive! The tough plywood and epoxy is gone, and the coupler looks intact. That takes a delicate touch.

 

[Bat-mite]

That's a color scheme I haven't seen before. Nice!

 

[Mugs914]

Thanks guys!!

The hardest part was getting to the little ridge of epoxy that formed way up on the forward edge of the coupler when it was originally pushed up into the tube.

The next step was to order a few things from Giant Leap. Amongst some other goodies, I got a 7" coupler tube, two coupler bulkheads and one airframe tube bulkhead that will all become the new av bay.



(The little pack of jelly beans was a neat surprise!)

I committed surgery on the coupler tube, cutting out a strip that was maybe 3/8" wide. The edges of the resulting gap were sanded smooth, covered in epoxy then brought together. The whole thing was wrapped in parchment paper and slipped into another coupler to dry. The strip that was removed was epoxied over the seam on the inside. When the epoxy cured I had an av bay tube that would slide inside the original coupler.

 

[Mugs914]

This is the av bay with the bulkheads. The larger one buts up against the original coupler when the thing installed.

 

[Mugs914]

This is the av bay mocked up. The piece of all-thread is a bit too short to allow the bigger bulkhead to be fitted but you get the idea. The bay will be secured by four (maybe six, haven't quite decided) 6-32 screws through the airframe, coupler, and into blind nuts in the av bay. The screws will be where the aft aluminum wrap sits, so it will have some real fasteners to keep the simulated ones company.

My original idea was to use a single length of all-thread through to av bay with forged eye-nuts on either end to attach the harnesses, but now I'm wondering whether I should go with two all-thread rods and eye bolts or u-bolts. Do you guys think the single piece all thread would be sufficient, or should I go with two for safety (and/or psychological) reasons?

 

[Nytrunner]

Enter the rocket science!

Bad deployment >50g acceleration * mass of your nosecone/payload.

Is one rod strong enough? SHouldn't be too hard to find the strength of the average threaded rod

 

[K'Tesh]

Nice thing about "U" bolts is that they can't easily be undone by the spinning of the rocket during recovery. Don't know how often that happens, but if you were to forget to epoxy your nuts and bolts to the bulkhead, it's within the realm of possibility.

 

[Mugs914]

Yeah, you guys hit on the points I was considering. I guess it was a bit of a dumb question, really. Maybe on something smaller and lighter or where space was an issue it would be a more viable option. No reason on a four inch rocket.

Besides, it's best not to ask too much of a single piece of steel that has had 20 stress raisers cut into every inch of it.

 

[Mugs914]

It's been a spell, but I finally got back to the L2 project. Not much to show, but a bit of progress on the av-bay.

Haven't decided on a layout for the altimeters yet. There's going to be plenty of room for everything, and more besides. Nice change from the 3" bay I just finished!

Here are a few pics:

 

[mbeels]

Nice idea with the U-channel. It's hard to tell from the photos, does the threaded rod pass underneath the plywood sled?

 

[Ez2cDave]

No. No computers were used (or harmed) in the making of this rocket. Back then I used a graph pad, pencil, various engineers scales (rulers), calipers, a calculator, the Barrowman equations and the Giant Leap rocketry catalog! That, help from knowledgeable friends and a bit of common sense would get you where you though you should be. Then you flew the thing to see if you got it right !

Amen, Brother . . . "Old School", Rules ! ! ! . . . ( I'm 58, started flying at age 6, with help from Dad ).

I never use a computer to design my rockets . . . If my brain can't do it, it shouldn't be done - LOL !

The ONLY time I will EVER use a Sim program is when I do my Level 3 . . . The rocket will be TOTALLY designed "on-paper" ( I don't fly "kits" ) and I will get someone who is "Sim-Savvy" to program the Sim for me, so I can meet the Cert requirements for a "Sim".

BTW - You left out a Protractor and Compass in your set of Designing Tools . . . I wasn't quite "Old School" enough to mention a Slide Rule, though !

Dave F.

 

[Andrew_ASC]

Yeah man not gonna lie I’m jealous of your 4” av bay size. I gotta gut my 54mm MD bay and spend more time on it when I get back home again. You have all that space I don’t have. Looooooool!