Modification - Hermes A-1 {Modification}

Modification Hermes A-1 Modification

Modification - Hermes A-1 {Modification}

Contributed by Dick Stafford

Construction Rating:
Flight Rating:
Overall Rating:

Published:	2011-03-24
Manufacturer:	Modification

Brief

This review explains how I converted a sport scale Semroc V-2 xKit to a Hermes A-1.

Components

The following parts are required:

One Semroc V-2 xKit, using the scale fin option
3/32” balsa stock
Thin Kevlar twine
Motor hook
Mylar sheath to hold the motor hook (optional)
Lead shot

I’ll start by saying that the quality of the cone and tail cone was great, like on the first V-2 xKit that I built. On my second, these were a little rougher than expected so I was happy to see the quality was again excellent. As usual, Semroc’s laser cut fins were well appreciated.

Construction

I started the build with the motor mount. This is your typical mount that incorporates a motor block and spring motor hook. I used a mylar sheath to hold the hook in place. I have no idea where it came from and a couple of wraps of tape would work just at well. I also tied and epoxied a short piece of Kevlar twine to the tube. Because of the hook and twine, I had to sand the pre-drilled tail cone a bit. After the motor mount was installed in the tail cone, I had to notch it so the hook would flex. This is not optimal for a scale build, but I wanted the hook.

This is a very sport scale model as I worked with a photo of the Hermes on my computer screen. I entered the measurements into, and manipulated them with, a spread sheet. I found the fin tabs would be 0.5” square and the The dimensions of the upper fins, once rounded to even ruler dimensions, are: root - 2.125"; tip - 1.25"; sweep - 0.75"; and, span - 0.5".

Because the fin tabs were just glued to the end of the stock fins, I laminated them with self adhesive label stock. The edges were then sanded and sealed with thin CA.

When I ran the RockSim, I found the CP was about the same as the stock xKit with the scale fin option. I bored the nose out and added enough lead shot to set the CG. The hook-eye provided with the kit was embedded in the lead/epoxy slurry. It weighs 3 oz without motor and RockSim says a C6-5 will work, a B6-4 would be OK with a long rod.

I used the stock rubber cord, tied to the Kevlar leader. I didn't use the stock 'chute, opting to use a nylon one instead.

Finishing

Here are the steps I followed:

I primed it then painted the white base coat.
I masked the fins and over painted the edges to seal the tape.
When dry, I painted the fins.
I marked the nose cone tip by positioning a clear plastic tube and slightly scoring the white base coat.
I sprayed Rustoleum red primer into a plastic container and, using a micro brush, followed the score mark.
The bulk of the tip was painted with a regular brush.
The lower stripe is 2 pieces of vinyl pin striping.
The stripe on the cone is also vinyl tape. I carefully scored one edge (every 1/16"-1/8") to allow it to conform to cone. This is the first time I've done this and it seemed to work well. There were 2 - 3 places where I touched it up with a Sharpie.

Construction Score: 5

Flight

Because I had retrofitted a motor hook, all I had to do was slide the Quest B6-4 in. I used a square of Quest wadding wrapped around a wad of dog barf and attached a 12" nylon 'chute. The flight was nice with ejection a couple of seconds after apogee.