The Armar Gorrion is an Argentinian home build aircraft, (to arm a sparrow), this is a 1/4 scale representation designed by Denis Tapsfield (circa 1980's) and is built from a Radio Modeller plan RM265 and is 75" wingspan designed for 61 2 stroke engines
I got the model from a deceased modelers estate along with 2 others in my current hanger. This one was the nearest to being complete and had been test flown at our flying field some time previously.
Originally, it came with a HB 61 2stroke installed with a home build silencer which was ingenious in construction but was any thing but gas tight and the bulk head was severely fuel soaked, I changed that for a Pitts style muffler, the engine was installed as a sidewinder. Following radio installation and test flying, which it suvived it was determined the C of G was all wrong and the engine when it ran was limited in power. It had a Perry carb which was very difficult to tune, I eventually swapped the carb for an Irvine type from a Irvine 40, it just happened to fit without modification of the carb or engine. The running of the engine was much improved but still lacked enough umph! to succesfully power the model.
The next mod was to install a four stroke 91 engine, the first being a Magnum XL 91 and more recently a ASP 91 FS
I had probably more than a dozen flights with the Magnum installed but it was never spritely and had just over 8 ounces of lead bolted to the bulk head to get the C of G right, the model was a pleasure to fly and very relaxing until the day the engine went very sick just after take off and I eneded up planting it in a tree on the periphery of the flying field, lack of depth perspective was my excuse. A 10 1/2 pound model unceremoniously being dumped from a tree to terra firma didn't do it a lot of good and I decided on a complete rebuild.
The pictures above are of the rebuilt model, in a effort to lighten the wing loading I rebuilt the tail plane and rudder which looked like they where made from mahogony, well at least balsa that hard. The cowl was remade using glassfibre and glassfibre molding techniques, something that was new to me but a technique I wanted to experience. A new ASP engine installed with a custom exhaust manufactured by me. It turned out the CG was spot on without any lead adding (previously had a big lump screwed to the bulkhead )and tipped the scales about a 1lb lighter. Never got it off the ground so to speak during the test flight, it rolled left just after take off, to which I applied right aileron and it rolled more left, basically rolled in at full bore from about 6 foot and completely wrecked the front of the model and the wing struts. I had the ailerons going the wrong way...!
Rebuild 2 focussed on the front and the wing struts and the left wing, also modded the build to remove the tank access hatch from the top of the front deck, that now goes in from the inside, this made planking and finishing the front deck a lot easier and the model another few ounces lighter.
New covering is doped tissue over the fuselage with cellulose primer and top coat with Solarlac Clear Coat on top, the wings are now covered in GlossTex, previously it was badly covered in solartex which was a nightmare to remove from the fuz.
Tigger now works the controls
Sad fact is while it does look good it doesn't really fly any better and if any thing ground handling seems worse than before, it is a hand full on the ground but I have managed to get it aloft twice now. I am wondering if I could flatten the u/c a bit to reduce the wing attack on the ground, I think it has a tendancy to try and get off the ground before it's really got up flying speed, which is why it tends to roll on lift off.
Andrew's Model Site Web Page