Mega Alpha Rebuild thread

Lots of build threads, so here's a rebuild thread. I have some time off work the next 1 1/2 weeks so I hope to finish the rebuild of the Mega Alpha. It's my Maxi Alpha sort-of clone. Same diameter and height but with bigger fins than the Maxi. I originally built it in April/May. It had a cato earlier this season that cleaned out the fin can, and so I'm rebuilding it to be a true mid power rocket. I started the rebuild a few weeks back, so some of these photos are from back then.

Here it is with the rest of my Alpha family, before the cato.

The cato was on an Estes E12-6. The motor appeared to burn all at once, and since the original motor mount was flimsy, the mount went for a short 30' ride straight out of the top of the rocket. Damaged the cone as you can see. The fin can was almost unscathed, so I got the idea of doing a proper rebuild, with a solid 24mm plywood-loc tube mount.

I ordered the rings and tube from LOC, and got the Aeropack retainer from my local vendor Animal Motor Works. You need to get the '24mm L2' retainer if you want a perfect fit on LOC tubing. The other sizes (L and P) are for other vendor's OD tube sizes. JB Weld where the rings mount to the tube, as well as to secure the retainer body to the end of the motor mount tube. The struts that you see in the can are balsa reinforcements, so it's not a TTW design (original can survived the cato so my goal was to use it as is but with some beefing up).

The motor mount was installed using West Systems epoxy (205 fast hardener, 105 resin, with some colloidal silica mixed in to make it thicker). Here's the completed booster section on the glassing stand. I build the stand from scratch (obviously!) out of scrap that was laying around the garage. I plan to fly the rebuilt rocket on up to G motors, so the next step is some reinforcement with fiberglass.

This is my first attempt at glassing. I also used West Systems (205 hardener, 105 resin) to adhere the 1.5 oz cloth. I opted to do each of the 3 segments separately, so I cut the glass to a rough fit, spread the epoxy on with a small foam roller (cheap one from Home Depot), applied the glass, and then smoothed with the roller and a bit more epoxy. Here's one of the segments drying on the stand. After its dry, I cut most of the excess glass off with a scissor, then sand (around 320 grit seems best) to get the edges of the glassed area smooth.

The booster is right now drying on the glassing stand. I installed one final wrap of cloth onto the upper portion. Now for the payload section. I cut the busted end of the nose off, and then drilled holes through the tube and cone. Plastic rivets will hold the nose in place. For recovery attachment, I built the bulkhead that you see here and installed a u-bolt.

The upper end of the payload section showing the bolt end of the u-bolt. I used some 5 min Loctite to assemble the bulkhead - plywood ring plus a 1" section of BT-80 tube coupler. The bolt studs will serve double duty as the mount points for the altimeter sled. It will be a dual deploy rocket, motor ejection at apogee and then altimeter controlled cable cutter to deploy the main.

Cut off nose mounted in payload tube, showing rivet holes.

The altimeter sled main section. To mount it I will attach it to a metal or wood strip, the whole thing forming a 'T' shape. The strip will have 2 1/4" holes drilled 1 3/8" apart, which we be used to mount the assembly on the u-bolt studs. My variation on the 'how to use nose as altimeter bay' theme. That red thing is the cable cutter from Archetype Rocketry.

Finished building the altimeter sled and mount. The metal strap is from a standard steel hose clamp, epoxied and nailed into the edge of the sled. The rubber hose segment provides a no-wiggle friction fit inside the nose cone. I still have to drill a small hole in the forward bulkhead for the ematch wire to pass through, and some vent holes through the top of the tube and cone shoulder.

I made a radical change to the Mega Alpha. It has always been prone to weathercocking, with the OR sims showing it as over 3 caliber stable. I decided to trim the fins, and so it is no longer an Alpha. The new config is 1.1 caliber stable with the largest G motor I plan to fly with, and a very acceptable 1.25 with an F51.

To do it, I drew my cut lines, clamped a steel ruler next to the line to act as a saw guide, and then used my razor saw to carefully make the cuts. I cut these:



from this:



to make this:



I really like the new look but now need a new name for the rocket!

"Beta" sounds like the next in line.

Handeman said:

"Beta" sounds like the next in line.

Click to expand...

Hah, not a bad choice. Certainly shorter than "Gallifrey Falls No More", which has popped into my head a few times today.

Ready to go. Might fly it tomorrow then back to the paint station to really finish it.

This rocket flew straight as an arrow on a CTI F51 to 1182'. The chute unravelled from the burrito at apogee, so not a true DD flight. I figured out what I did wrong and will correct it before the next flight. Also flew it empty (no electronics) on an Estes E12-6. Both underpowered and too long of a delay - I won't use that motor again in this rocket.

Oh, and got lots of thumbs up at yesterday's RIMRA launch for the name 'Gallifrey Falls No More', so I'm sticking with it. Dr. Who fans among the ranks of rocketeers? Imagine that!