Geoff Graves describes his joint scale project, originally started with his greatly missed modelling buddy Derek Martin
words >> Geoff Graves
photos >> Geoff Graves, Stuart Mackay
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The Waco YMF-5 was first started almost three years ago by Rolls Royce Model Club ex-chairman Derek Martin. He had previously owned a 1/4 scale Waco YMF-5 that he unfortunately lost at a Rolls Royce scale day. The Waco was Derek’s late wife, Mary’s, favourite model, so he decided to set about building another one, but this time he scaled it up to 1/3 scale.
I had been Derek’s friend, co-pilot and helper for a good few years, so we decided to make it a joint project and build the new model together. Derek did all the calculations and measurements, and drew up all the plans, using references and plans from the full-scale aircraft. He also made all the fibreglass plugs and moulds for the cowl and wheel spats, and made the fuselage and tail, while the wings and central section were built by me.
We had originally designed the model around a MUSS 116 two stroke motor but at a late stage I had the opportunity to get a Moki 250 Radial from one of my good friends, Stuart Mackay, who has been very helpful with the installation and set-up of the Moki. The Moki 250 has really added the final touch to the model and also helped to get the CG spot on, with no added nose weight. The Moki has plenty of power behind it and only needs to be at third throttle for normal flying.
I covered the airframe using Solartex, three coats of dope, and then finished using 2k primer and two coats of 2k solid colour car paint. Being in the motor trade I am very lucky to have access to state-of-the-art spray booths for the painting stages.
The cockpit dashboard was made several years ago by the late Harry Harland, of the Yorkshire Old Farts, who was a close friend of Derek’s. The scale pilot was from The Prop Guy and had to be purchased from America.
The radio is controlled by Futaba, with two 2S LiPos feeding a Powerbox power supply system, for all flight controls. There is a separate 6V 5-cell NiMH battery for engine ignition and an 800 mAh NiMH for the landing lights.
The model was registered with the LMA with a target weight of 20kg, with Glenn Masters as the inspector. However, the LMA now has a new limit of 25kg before CAA exemption is required and the final weight of the Waco comes out at 23.5kg with fuel, so no exemption is required.
Unfortunately, Derek’s health took a turn for the worst in the last 18 months of the build, so he didn’t get to see the model fly. But he did see it almost finished and painted and was very satisfied with the outcome. I wanted to honour his memory and decided to add Derek’s name to the artwork on the Waco, by signing his name on the side of the cockpit.
The maiden flight was carried out in July 2021 at the BMFA headquarters in Buckminster, by myself, with Glenn Masters at my side for support. Although it was a nerve wracking build up, the model flew superbly, with only a couple of clicks of down elevator required for straight and level flight.
I have now had several flights with the Waco and have started to explore the acrobatic capabilities a bit more by performing loops, rolls and stall turns, testing the rigging wires, with no issues to date.
The model has been a pleasure to build and I picked up a lot of tips and experience along the way from Derek. I hope to enjoy flying it for many years to come and remembering my good friend and master aero modeler Derek Martin.
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