Built-up fins for the new HoJo
 

With the MR painting disaster now behind me, I sliced open a new Estes Honest John kit.

Instead of doing the 3-layer balsa fins, I'll try doing built-up fins of a balsa core and cardstock skins--much like the old pro-series Patriot.

After separating the (4) fin cores from the sheet I use one of the laminate leading edge pieces as a template to pencil a line on each side of each core.
Using the blunted point one of "the Vixen's" old nail files I press a groove into each side of each fin core.
I then apply a line of Titebond Red into the groove on one side only for now.
I then register a piece of 1/16" dowel into the glued groove.

I hope this works, or I'll be cutting (4) new core pieces!

TBC

I then repeat the same technique for the other surface of each fin core. I'll let these dry overnight.

Time for a Scotch and an IPA. Good night.

TBC

Very cool mod!

Enjoy a night's rest.

Thanks!

...and I did.

Now for the skinning (or is it enrobment?)

First I use the Corian board covered with 220 to scrape bevels into the leading and trailing edges of the fin blanks.

For the skins I'll use my best sheet of .015" acid free card stock that's polished on one side.

Next I cut out an oversized blank and then use the unused balsa fin pieces as patterns to make the cuts. The leading and trailing edges are of course extended because the skin will be folded.

The skins are then cut out with a fresh #11 blade. I then use the steel ruler and the blunt end of "The Vixen's" nail file to press a groove into the cardstock for a crisp fold.

I then apply Titebond Red to the leading edge, trailing edge, and center rib of the core and lay and hold skin onto it until the glue grabs.

One skin down--seven to go!

TBC

Even though there's only one skin on this fin assembly, I test fit the fin into the slot of the fin can. Some trimming and detailing will be required, but I think the fin mod. will work.

TBC

The glue is set on the first skin of all four fins and I now repeat the process with the other side of each fin. After the glue has dried again I cut the excess from the leading and trailing edges.

Now all four fins are skinned--except the outer tips still have to be capped or filled (I haven't decided which.) There will be a buttload of fitting and trimming to do, but I think it will still be easier than trying to get this crisp of a bevel on this much surface area by hand scraping.

We'll see.

TBC

Now for the fin tips.

As it turns out, covering the fin tips is easier than I'd thought.
First I use the Corian board to sand the tip flat. I then dispense an amount of Squadron Green onto a paper plate and smoosh the fin tip into the putty--extruding the putty up into the void of the tip.

After the Squadron Green dries I'll sand it smooth.

TBC

Very nice work. Can't wait to get my hands on this kit. I have the mini and the BT-55 versions. Both fly great.

Thanks! I've always loved flying the HoJo--from the Mini to the Maxi Brute.

Now that the Squadron Green is set I've scraped the leading and trailing edges to smooth them. I then give the edges a soak with thin CA to strengthen them and to prevent them from "fuzzilating"(?).

TBC

Now for the mounting.

It was necessary to undercut the skin on the root edges of all of the fins to ensure the tab reached the engine tube. Since I'm gluing balsa to BT and balsa to styrene in the same operation I'll use epoxy. I mix and apply the 15 min. epoxy to the slot tab and to the root of the core of (2) fins and insert them into the fin can.

As the resin hardens I maintain the alignment with the steel ruler.

TBC