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Clipper III


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Not exactly a build log but the latest results from the workshop. I wanted something a bit Superstar like but couldn't find a good enough plan (the ones on the freezone are too low-rez). I had this plan in the box since the mid 70s and looked at it from time to time. What with all the free time we have these days I decided to have a go. 70s builds are quite wood intensive so I changed the construction methods, using sheet over formers and stringers for the fuz and the more usual square spar top and bottom rather than the method shown of cutting halfway through a full depth spar. I have added motorised retracts and the usual 2 servo aileron control. To get prop-to-ground clearance. I had to cut the front of the wing root back to allow room for the retract nose gear. I guess in the old days they didn't use anything bigger than an 11" prop albeit very coarse pitch. Balancing may be an issue but I have the choice of using an Irvine .61/.72 or a .53. With such a long nose moment it may be possible to use the smaller engine if the weight can be kept down to the 6Lb.

A.

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  • 9 months later...

Clipper III painted and fuel-proofed.

Having completed it I have a quandary due to it's long nose, fitting an engine powerful enough makes it too nose heavy and fitting any of the ones I have that balances it won't be powerful enough. Having fully finished the airframe it seems a pity to hack it about to fit batteries and/or servos in the back. What I need is an engine that weighs no more than 600g (with silencer) but has the power of a good 60 2stroke.  My original plan was to use an Irvine 72 but this comes out to 750g. I looked at using a tuned pipe for this plane but it just doesn't suit. I trial fitted my YS63 FS but re-reading the rules for classic pattern competition, supercharged four strokes are not allowed.

The plan shows the CG back as far as 70% which must be a mistake by the designer Chick Holland or who ever drew the plan, this would mean that the nose wheel would be redundant as 70% CG is behind the main gear. I decided to use a much more conventional CG which is still difficult to achieve. A possible answer to this may be to use the latest OS55, but loath as I am to buy another OS engine after all the plating problems this may be the only answer.

FinalScheme.jpg

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Murat,

I considered that, it would clean up the lines of the front end and Epower is within the rules but I made no provision for a battery hatch.

On a quick recalculation and jigging things around a bit I think an OS65 at a 100g saving over the Irvine72 would fit OK but I'll have to look at the bank balance before I pull the trigger on that one.

Many thanks for the compliments.

 

A.

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Takes me back a long time since this was my very first F3A model. I built a pair of them, one for myself and the other for Jim Davis. These had the long acetate canopies as per the original design. We used HP 61s and I do not remember there being any cg problems, about 40 to 45% would sound about right to me for the swept wing.

Cannot remember what happened to mine but I built another with a differently shaped fuselage to simplify the construction. Got shot down by a rogue Tx at my first comp., the Rochester Airshow but borrowed Jim`s Clipper and came 4th which was very pleasing since there were some `names` there and I had never flown the very much out of trim model before.

All of my later designs were a development of this model in one way or another, i.e. the Reaction and Dragon.

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I wish I'd kept my HP61, HP engines were light for their capacity so it would have suited the design.  The wing isn't actually swept although there is more taper fore than aft. There was no way of getting the specified canopy these days so I just painted it on over a sheeted structure. I also changed the wing internal structure. The external shape is true to the original design although I did leave out the fin strake.

IMG_20200625_105548856.jpg

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The original fus construction was quite simple, 3/16th sides, 1/2" top and 1" triangular to join them, slotted to bend then shaped. I seem to remember a weight of 6 1/4lbs dry.

Many models |I based on this required a little lead in the tail, as do my current Dalotels which are remarkably similar.

Not sure what came first, the Clipper or the Bulldog by Kieth Jones. Somebody must have copied one or the other because even the fin was the same.

I later increased the wing area a little because things like pipes, higher cell count batteries, retracts and a fuel pressure system pushed up the weight to 9 3/4lbs with fuel and the loading would have been above the FAI competition limit of 24 1/2oz/sq.ft. This was used on my `Golden Oldie` design which I flew to 8th place at my second Nationals. The Super Bulldog used my wing design.

Just a little history.

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