Old Timer (oz9926)

About this Plan

Old Timer. Vintage style sport model for radio control.

Quote: "We used to call them 'F-Crates' in Sweden in the fifties. I guess there is a similar nickname in Gt Britain. There were many designs available, but they all had one thing in common. The wing had a double dihedral, was mounted on a pylon and often had elliptical wingtips.

The 'Oldtimer' looks like, but isn't, a genuine Oldtimer. The model has been changed to fit R/C on the following points:

1. The cambered or thin free flight profile is replaced by a semi symmetric, fairly thick wing profile, which makes the model easy to trim.
2. The CG point is at the normal 25-30% from the leading edge and the stabilizer has a symmetric profile. The F-models almost always had a lifting stab and the CG close to the trailing edge.
3. The wing is of a simpler design than that of the real oldtimers.
4. The thickness of the longerons is increased to 6.6mm from the usual free flight dimensions 3x3 or 4x4.
5. The wing has spars from spruce and webs from ply to withstand the stress of the extra weight of RC equipment.
6. The fin is larger to give a more stable flight - this model isn't intended to float around and search for thermals by itself!

But we have kept the following attractive attributes of the old F models:

1. The stabilizer is removable, if you want.
2. The pylon mounted wing with its double dihedral that maintains extreme stability. The fuselage is hanging down under the wing as in a parachute.

We covered all our Oldtimers with opaque Excelcote. It produces a fine Oldtimer look, almost identical to fine Japan tissue or silk. An advantage of this is that you may easily inspect the inner parts, including the RC equipment and the tank through the covering. This is fine if you have made a fine framework at the building table. Otherwise ordinary film is better.

The engine choice is very interesting with these models. Different engines will give quite different planes to fly. If we start at the lower end you may fly the Oldtimer with as small as .09-.15 engines. This will produce a very docile model, like a motorized glider. In this case, don't fit an undercarriage.

If you want the 'action' option you should choose at least a .20 engine. Now the model starts to climb almost vertical like the contest models of the fifties. The .25FSR engine is the best choice, by my standards.

A very special derivative of the formula is born when you fit a racer .25. This model zooms up to 200-300 metres in 10-20 seconds with a deafening howl..."

Old Timer, RCM&E, December 1988.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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