Mark One (oz11665)
About this Plan
Mark One. Radio control sport parasol model. Wingspan 63 in, wing area 610 sq in, for .30 to .40 power.
Quote: "Mark One. When David Boddington updated his Barnstormer design the result was this sleek parasol wing sportster.
Mark One was designed as a tribute to a modeller who has suffered more than his fair share of trials and tribulations over the years. Mark Underlin is a member of the Model Pilots Association, who, with his wife Amanda, regularly attends the MPA aeromodelling weeks at the Haven resorts, and MPA events at Old Warden and Grendon Underwood. It was after one of the Filey modelling weeks that we learned of Mark's health problems. Mark has been suffering from kidney failure since the age of eighteen and two transplant operations have proved to be ineffective, so he has to resort to dialysis on a daily and nightly basis. In spite of these severe handicaps Mark took an absolutely full part in all of the aeromodelling activities on offer at Filey, both the building and flying events.
When Amanda was organising a surprise 30th Birthday party for Mark it offered the perfect opportunity to demonstrate the caring side of the MPA. Although time was fairly short it was decided that we would present him a model, ready built and complete with engine and radio control equipment. Amanda and friends purchased the OS 40 Surpass four-stroke engine and a mention to MPA members who had attended the Filey week, brought an immediate response with donations sufficient to cover the costs of the Hi-Tec radio control equipment. Ray Bullen provided some of the Artmill balsa for the construction and Chris Dickens kindly offered his services, plus additional materials, for the model.
For some time I had thought about updating my Barnstormer 63 design and the presentation to Mark made the ideal excuse for this project. Having just reached the solo stage at the MPA Devon Cliffs week, Mark was ready for a stable sports model to give him plenty of flying opportunities and to build up his air time. Chris worked like a mad thing to get the model completed on time and the presentation at the 30th Birthday came as a complete surprise - it was only because of the dozens of guests at the party that Mark didn't go out to fly the model immediately! The fact that the model has now been flying for over three months and has clocked up many flights is testament to Mark's flying abilities and to the rugged nature of the model. Photographs of the model were mostly taken after the many flying sessions, hence the signs of wear and tear.
Design: There is obviously no need to explain the name and the genesis of the model, which is directly related to the Barnstormer designs, the first of which is now some 25 years old. Changes made to bring it to Mark One standard includes the incorporation of sweep back on the wings, the cabane struts being simply formed from pianowire, a cowled upright engine, enclosed cockpit and the use of all sheet tail surfaces. Flying characteristics have, if anything, improved on the original and the wing sweep, together with the use of a four-stroke engine, helps to achieve the correct balance point without resorting to added nose ballast.
There are not many decisions to make before you start chopping and sticking but check for the fit of your engine on the bearers, also the spacing for the servos. Note that the fuel tank is housed in a plywood tube with access to the tank from the front of the fuselage. This has two advantages; the tank is totally separated from the radio equipment and the tube helps to strengthen the forward part of the fuselage. Check the dimension of the round fuel tank you are to fit; note that the tube ends in front of former F4. Wing struts are not 100% necessary from a structural consideration (for non aerobatic flying) but they do improve the appearance considerably. If you are interested in a more aerobatic performance you should certainly fit ailerons and I would suggest reducing the wing dihedral by half.
Wings: Wing panels are built flat over the plan. Pin down the lower trailing edge, rear spar and lower main spar (supported on 1/16 packing). If ailerons are to be fitted they should be constructed at the same time as the wing, the ailerons being cut away after the panel is completed.
Glue the ribs to the spars, canting the root rib to the required dihedral angle, followed by the top main spar, top trailing edge strip and the 3/8 square leading edge. Leave to dry before adding the top leading edge sheet, capping strips and top centre section sheet. Remove from the building board and glue the 3mm plywood strut fixing pieces and wing strut blocks in position, plus the wing tip pieces and gussets.
Sand the root ribs smooth and join the two panels, propping up each tip by 1-1/16 in. When dry remove from the board and cut slots for the dihedral braces; glue them in position supporting the tips to the correct dihedral. Leave for the glue (PVA) to set thoroughly, prepare any servo boxes and aileron linkages and glue the lower leading edge sheeting, cap strips and centre section sheeting in place..."
Mark One, RCM&E, November 1992.
Direct submission to Outerzone.
Supplementary file notes
Article pages, thanks to RFJ.
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