Hawker Hurricane Mk103

Discussion in 'Member Project Logs' started by pictsidhe, Sep 24, 2019.

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  1. Sep 24, 2019 #1

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

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    Many of you will be familiar with this project, I've posted bits here and there on the forum. I started a discussion thread here about a year ago.

    What is a Mk103 Hurricane? It's a 2/3 scale AC103 legal Hawker Hurricane, of course!

    Why a Hurricane, and not a Spitfire, or P-51?
    Well, I'm British, so I'd prefer a British plane. The Spitfire, while a great aircraft to fly full size, will not scale down well. At full size, it's a small aircraft. It does have 240sqft of wing, so something would need to be shrunk, and the fuselage has very little scope for that. It was also a real handful on the ground thanks to its narrow gear. The Hurricane had a much roomier fuselage. It also had a much thicker wing, which is great structurally. At 2/3 scale, I'm looking at around a foot thick root. That's thick enough for a strong cantilever wing. At 103 speeds, compressibility won't handicap the speed like it did with the full size aircraft. Unlike the spitfire, the pilot is pretty close to the cg. That's important if different weight pilots want to fly it. All the important bits are about the right size and in the right place. The thick wing is icing on the cake.

    I am planning to skin this project in Coroplast (or clone). Behind the cockpit, a monocoque will work. Compared to the Minimax, it looks like I can build cockpit backwards lighter and stronger with Coro. The fuselage from cokpit forward and 2/3 of the wing will get a truss somewhat like the original. This construction is actually more like the Typhoon. I also want to have folding wings for ease of transport. The Fairey Firefly fold looks perfect. Retracts will be 'rubboleo': telescopic but with rubber springs. Gas springing is a PITA to execute. This again compares very well weightwise with the Minimax. I need to change the linkage a bit compared to full size for weight, but it will fold the same. I have selected 4.80 x 8 wheelbarrow tires and plastic wheels. Lightweight and cheap. A little smaller than scale, but much lighter than scale sized ATV tyres. I'm going for 40% chord ailerons in order to improve roll rate somewhat from the glacial rate scale ones would give. Probably keep split flaps, chord may increase to suit the wing fold. Wing spar will be a triangular truss. Lower main spar in the same place as the original. Upper spar a bit further back at about 25% chord, depending on where my knees clear it best. Single rear tube. This will give great torsional rigidity, a shear centre well forward and the mass fairly well forward. 7075 front spar caps, probably 6061 rear tube and trusswork. I'm going to try and leave space for paintball guns in the wings! Though they are a very long way off...

    For the engine, I plan to run an industrial v-twin swinging a huge nearly scale prop (ground clearance). I have a blown Intek 656 for mock-up and possible use as a ground test engine. I'd prefer an 810, but weight may dictate the 627 Vanguard.

    I've been picking away at the design for a year, so many of my early Great Ideas are now in the 'round file', mostly after failing maths or practicality tests. Others keep joining them, but the rate is slowing!

    A couple of days ago, I paid actual money for a sheet of 3/8 ply to mock up the cockpit forward. I cut a few from some really nasty OSB a while back, but I'm going to junk them as they are heavy and flimsy. I need to firm up the seating design and find out where the pilot cg will be before I can get into more detailed design. I'm currently lofting bulkheads after work. The cockpit bulkheads will be 70% scale. Two reasons, one to fit me in, the second is that with the nose bulkheads scaled to 65%, I should be able to see where I'm going...

    Span: 26'8"
    Wing area: 114sqft
    Length: 21'4"
    Height: Tail down, about 7'3 with one prop blade straight down. About 8'5" with one blade straight up
     
    Mr.B., Matt D Murdoch, bifft and 2 others like this.

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