Sharkface (oz4416)

About this Plan

Sharkface. 22in wingspan radio control model for up to 1.5cc engines and rudder only control.

Quote: "Eric Clutton reveals in his own inimitable way an approach to small-field R/C aerobatic flying on a low budget, introducing the full size plan 'Sharkface' for .049-.09 (.8-1.5cc) engines.

One unfortunate deterrent to radoi control interest is that it is too complicated - how often do we hear, I would have a go at radio, but I can't be bothered going to all that trouble! I'm inclined that way myself, so I have sympathy for this view!

Working on the theory that if anything can go wrong it certainly will to prove a point, I decided to see what could be done about simplification of this R/C business. This becomes a matter of elimination. The first things to go are valves - those little glass bottles full of bits of wire that need a power station to operate. All-transistor receivers are now virtually indestructible and will operate off quite small batteries.

Next, it is possible to fling out all those chattering little relays. These are fairly reliable but they are not crashproof - not for the sort of crashes I have anyway!

Saving weight: Switches can easily cause trouble, so out they go. The Receiver will simply plug into a three pin socket when required. These sockets can be cut down quite a lot if they are not mounted on a bulkhead.

Compound escapements are light and they work very well, but they are more complicated (that word aghain) than the ultra-simple sequence type which are also more crash-proof.

The escapement should pull in on a 1-1/2 volts to be safe, and some eg the Elmic Conquest may require some slight adjustment of the armmature spring for reliable operation on 1-1/2 volts. Don't overdo this or vibration will take effect.

Batteries: That practically takes care of the selection of the radio gear: all transistor, relayless and with a simple escapement, all operating off 3 volts. The use of these small batteries is a great advantage as, if the model stops suddenly the heavy parts will just keep on going, and the 'lighter' they are, the better!

This equipment could be installed in an average type of radio-cum-sports flying model, and some pleasant flying is possible - whenever the weather is suitable! This is unfortunately not very often as the average single channel model tends to disappear downwind at a fast rate on a normal windy Sunday. To 'penetrate' into the wind and make all-weather flying possible, the model must fly fast - there is simply no other way to do this.

To fly fast we must have plenty of power. A heavy model will not penetrate unless it has a powerful engine fitted - it's the engine capacity in relation to the model size that counts. Also a fast flying model will hit the ground with quite a bump if something goes wrong, so it must have built-in bounce. One of the best ways to do this is to reduce the overall size of the model; this means that we can use a relatively small engine and the smaller models are easier, quicker and cheaper to build.

Size of the model: I decided to build mine just large enough to hold the radio equipment and this, together with a reasonable length for the escapement rubber, almost designed the fuselage automatically. An upswept nose helps to reduce landing shocks. Did someone say undercart? This unneccessary complication would add weight, drag and building time - and trip the model up when it lands.

Wings are a necessary evil on RC models, they are often tricky to build and are the first component to break, so my wings will be as small as possible - consistent with a reasonable glide. Built up wings do not have to be flimsy. A glance at the Sharkface plans will tell you this! The prototype was covered with heavywight tissue and has yet to receive any structural damage apart from the odd scrape where it has clobbered the runway.

For those who like to live dangerously the 1.5cc diesel is the obvious choice, but be warned - you need hair on your chest for this one! Sharkface does not become vicious however, and things happen only slightly faster. Rudder movement may have to be reduced for the less intrepid..."

Direct submission to Outerzone.

Update 04/06/2017: Added article, thanks to spitfireflyby.

Update 2/11/2023: Added a vector format version of the plan, thanks to theshadow.

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