mgnostic

I scored an interesting purchase at an auction today. A set of Hobby Helpers plans for a PT19. There are three sheets printed on both sides. The plane would span 72" but calls for a K&B Torpedo .29 and a Babcock BCR 5 tube receiver. The plans are described as "Group #856. The accompanying writeup is copyrighted 1956 Smith and Street Publications. Three channel control, the plans show Bonner escapements and a K&B 2 speed needle. Does anybody know anything about the plans or the plane?

Michaelj2k

It's a Chuck Hollinger design that was later adapted to a kit by Jetco then by SIG after Jetco shut down operations. Kits occasionally show up for sale here and there but the plans build is much simpler than the kit. Jetco redesigned it to build the wings on a flat board with each rib split into two parts. The bottom section was added when the panel was completed. With a lot of work, it can be converted to four channel operation with lowered dihedral and a one piece wing. The construction article was published in 1956 in two pieces by Air Trail Hobbies for Young Men which later became American Modeler.

mgnostic

Thanks for the info. The plans are in fair shape and the previous owner had already traced a set of rib templates. I'm going to see if the local Kinko's can make me a copy of the plans to build on top of. The firewall would need to be set back a bit but it would probably make a cool project with a 4 stroke .60

buzzard bait

The full scale is very slow and stately in the air, and it has a lot of dihedral. If you want to capture that character, I would keep it light and go easy on the mods and the power.

Jim

mgnostic

Hmmm, I'm thinking that it really wouldn't be that much work to convert. If anything, modern hardware would simplify it quite a bit. It looks like the original design weight was around 6 pounds. A modern radio would knock off quite a bit of weight. A .60 four stroke with a big prop ought to putt around quietly. In my initial look at the plans it looks as though the wing center section is permanently attached to the fuselage with removable wing panels. I suppose that is workable but it is quite a bit different than I'm used to.

buzzard bait

I don't think it would be hard to add ailerons, I'm just suggesting you find out what the scale dihedral was...it might be the same as the kit shows, even though it doesn't have ailerons. As far as the engine is concerned, I think the main thing is to avoid adding much weight and having to beef it up and add tail weight. As you say, the gear is lighter now, so if you don't make it heavy it's not going to need much power.

Jim

hogflyer

I have a set of the Hobby Helper planes for the PT-19 also. I thought I read someplace that when Hollinger designed it, he used the same airfoil and dihedral as the full scale, and even the outline, including the empennage, is the scaled correctly. If you build it, lets see a build thread. This plane has been on my "need to build" list for some time.....

Hogflyer