Wednesday, May 27, 2020

Gym Ripper Tail Surfaces

The vertical fin is a nice grade of 1/6" balsa. I'm going to used Cover Grip on the tail surfaces,
so I inset a piece of scrap with Super'Phatic. Now, there should be no warp or curl when the Cover Grip is applied.

The same technique to prevent warp is used on the horizontal stabilizer. (Note that the rudder and elevator pieces do not need this.)
Until the next time,
Hals und beinbruch
The Comet Kid

Gym Ripper Fuselage Part 4

Here I'm just illustrating the use of the MagnaBoard to line up the fuselage parts prior to using medium CA and Super'Phatic on the points of contact.

I decided to paint the cabane assemblies before gluing them in. Normally, I'd use some wood stain but opted for a match to the transparent yellow covering. The paint is from Michael's and it is a water-based acrylic with really rich pigment.

I learned this "trick" from one of the RC Micro World authors' articles. It was probably Bob Aberle. I've painted the areas where, in a much larger model, I would have had to wrap the covering down over the edge of some openings. You will see later that I will lay down the covering and just slice at the edges. It should look nice and finished.

Let's move on to the tail surfaces.
Hals und Beinbruch!
The Comet Kid

Tuesday, May 19, 2020

Gym Ripper Fuselage Part 3

This is the left cabane assembly. Stevens Aero really did some nice work laser cutting the plywood parts. Instead of just gluing the uprights to the crosspiece, I found some hardwood dowel material and working it down to about 1/16" diameter by chucking it in my Dremel and using a nail file for my sanding tool. I used the laser cut holes to glue in the dowels for a really strong mechanical joint. (Thanks to all the building mentors over the years who gave me an infinitely valuable "tool kit" of techniques to store in my iBrain.)
That wraps it up for today. This was a fun building day.

Gym Ripper Fuselage Part 2

I'm going to show what can happen with Super'Phatic. I glued down the bottom longeron and placed a dark grey magnet over it to hold it down after cleaning up what I thought was all the excess with a cotton swab. After a 20 minute cure, the magnet refused to come up. You can see how it ripped off part of the balsa fuselage side at that join. Grumbling to myself, I carefully saved the damaged piece with some careful X-acto surgery and reglued; I put down a small piece of plastic wrap before I set the magnet back for its clamping action.

Gym Ripper Fuselage Part 1

The overall fit of the parts went very nicely. Here's an overall shot of today's work. Both plywood cabane assemblies are glued with 5-minute epoxy and are sitting for an overnight cure. The fuselage sides are built in the time-tested method used on so many slab-sided models. First, build one side; on goes the plastic wrap and the matching side is built over it.

Monday, May 18, 2020

Gym Ripper Wing Part 10

The wing is all framed up and ready for shaping the TE, LE and light sanding.

Next comes the fuselage.

Gym Ripper Wing Part 9

This is my preferred method of applying Super'Phatic. I have a small artist's brush. A shot of glue at one section of the junction of the parts, and I literally paint it into the joints on all sides. Then the brush is immediately dunked in an old coffee mug holding plain water. It has lasted years.

Gym Ripper Wing Part 8

The right wing panel is laid up.

Gym Ripper Wing Part 7

You can see I relieve the tip sheet and two ribs to allow for a carbon fiber rod of about 1/16" diameter to carry the spar on out.

Gym Ripper Wing Part 6

The left tip panel is blocked up 2" as per the plan. I found that two VHS videotapes stacked to a perfect 2".

Gym Ripper Wing Part 5

This was an addition not called for in the kit. I carefully cut in the center panel ribs to glue in a piece of carbon fiber scavenged from a trashed ARF foamy. I like some strength. It's my glider building heritage. The red vertical inked line was referenced to the CG marking for the wing. I wanted the spar there.

Gym Ripper Wing Part 4

Here we see that Stevens Aero has accurately ( and I mean accurately cut even the 1/16" balsa gussets where called for on the plan. All the parts are ID'd with laser-cut numbers and letters so there's no fooling around wondering what goes where. Those Humming Bird Model Products Small Magnetic clamps are worth every penny. This is a small magnet clamp for building with 1/16th and 1/8th strip wood and for general holding and blocking applications. Small enough to fit inside smaller structures.  Laser-cut 1/16 ply and includes parts for 30 magnet holders (you will need 60 magnets). These dual-sided clamps are shown here with one using the 1/8" side on the trailing edge and one using the 1/16" side holding the gusset.

Gym Ripper Wing Part 3

Now I reveal the product that I discovered in my LHS. Super'Phatic Glue is a super-thin water-based glue that acts like CA but has the wicking properties of Titebond II. It is perfect for gluing balsa parts which are accurately laser cut.

The wing center section and the left tip panel go up in 10 minutes or less.

Gym Ripper Wing Part 2

I'm using the magnets supplied by Easy Built with the XL Magna-Board to line up the ribs, LE, and TE.

The large, dark grey magnets are from Easy Built. The unusual-looking jigging magnetic
tools at the trailing edge were purchased from Hummingbird Model Products. More about them in a later post.

Gym Ripper Wing

Gym Ripper laser cut wing parts

I decided to show all the nicely laser-cut parts. The model will be built on my Magna-Board which I bought from Easy Built Models. The quality of balsa wood is indeed very nice.

Gym Ripper from

This will be a rapid build of the Stevens Aero Gym Ripper. I'll talk more about the kit later and why I am building it now. (By the way, it is currently out of stock.)