F84 Thunderjet

Bill Stark

The May 2001 newsletter contained some results from the club survey. This seemed to show a lack of interest in PSS and design and build. To fill the gap, here are details of a just completed scratch built PSS version of an early American jet.

The Thunderjet was one of the first operational jets from the USA. Underpowered, but with a good range, it was used as a fighter bomber in Korea along with Sabres as top cover. It also served with several NATO Air Forces. Rumour had it, that it was so underpowered that even with rocket assistance, it only became airborne because the world is round!

I had always thought that it would make a good glider and found an article and plan in the June 95 QFI by Paul Jansen. This was for a small model of 35 inches span with a glass fibre fuselage, using the lost foam technique. I wanted something a little larger, a 48 inch span and of balsa and ply construction. The scale outline in QFI seemed good, so this was used as the basis for the new plan.

An article in the American magazine, Sailplane Modeller, recommended glassed 1/32" plywood wing skins for slope soarers, so this was used, minus the glass. The wing structure was built up with an Eppler 178 section, and the fuselage planked with 1/8" balsa. An excellent reference with colour photos was found in Aberdeen Central Library.

The wings, which were no problem to build but seem a little on the heavy side, should cope well with the Brimmond gorse. The fuselage took a long time &&&. it has been years since I had planked anything this big, but the end result looked fine.

How to strengthen and finish it? Two coats of sanding sealer were applied, then a leg from an old pair of tights was pulled over the structure and doped. This gave it a lot of strength and left several options for the final finish. How you get the tights is up to you!

In retrospect, it would have been better to fill the nylon weave and paint it, but I found that Solarfilm adhered nicely to the nylon, and so used that. The double curvature on the fuselage made this difficult, but then again, it's not going to be entered in a scale contest. For the canopy, a 2 litre lemonade bottle was shrunk over a balsa former and this looks OK. The tip tanks were carved out of blue foam.

The end result looks good from a distance, and the all up weight is 40 ozs at 20ozs per square foot.