About this Plan
Twophin. Single channel radio control model.
Quote: "Quick, strong and simple. Twophin, by Peter Holland.
WHY not build a manual pulse model? The system has quite a lot to recommend it in terms of simplicity, both from the constructional point of view and piloting technique. Our two free plans use the same radio installation so that if one chooses to make both, it is simple matter to transfer the complete control pack from one model to the other. In fact all that is necessary is to hook a piece of nylon on to the actuator crank and then switch on.
The 'Twophin' is a lightweight sports aircraft for 0.5 cc to 0.8 cc there being a variety of suitable diesel or glow motors either radial or beam mounted. The fuselage nose is just a lump of block balsa sandwiched be-tween the basic sheet sides and 1/32 ply doublers. This form of construction not only provides excellent 'thump resistance', but allows a variety of engine installations to be used.
The best way of adapting the model to suit a different power unit is to mount the motor of your choice on short scraps of hard-wood engine bearer and lock the bolts with a strip of wire soldered across the heads. If the motor is of the radially mounted type, a similar procedure is used for locking the bolts into a piece of 1/8 or 3/16 in plywood. In this case the plywood should be cut to fit b-tween the sides of the fuselage (1-9/16 in wide). Make the block shorter to allow the ply to butt against it when the engine is placed in position with the prop driver just clear of F1. A small hollow may then be made behind the bulkhead in the top surface of the block, to accommodate a small fuel tank.
The removable cockpit canopy, which has its own balsa baseplate, serves to cover the tank and generally tidy up the nose of the model, which sometimes tends to look rather like an afterthought on some functional machines.
The solid block nose also makes a firm anchorage for the piano wire skid. If the upper end of the wire is wound with cement coated thread and cemented in with a hole drilled in the block it will be held quite firmly. If one flies from a grass field, undercarriages on models this size are of very little use for take off and a skid is quite adequate for landing, thus saving drag, weight, expense, time and those inelegant nose-overs when the wheels become entangled with grass.
Features of the Design. The use of twin fins enable the rudder to be placed out of the slipstream, this serves to make the model more docile and give it an almost similiar characteristic on power or glide. The rudder need only be on one fin, simplifying the linkage.
If one wished to use an escapement, a half-span push rod could be used, as in Fig.1, but the model being designed primarily for manual pulse would need a slightly increased rudder area. The hinge line should be moved forward to 3/8 in. for this purpose and the corner of the tailplane cut to allow its movement..."
Direct submission to Outerzone.
Supplementary file notes
Did we get something wrong with these details about this plan (especially the datafile)?
That happens sometimes. You can help us fix it.
Add a correction
Do you have a photo you'd like to submit for this page? Then email email@example.com
User commentsNo comments yet for this plan. Got something to say about this one?
Add a comment
* Credit field
The Credit field in the Outerzone database is designed to recognise and credit the hard work done in scanning and digitally cleaning these vintage and old timer model aircraft plans to get them into a usable format. Currently, it is also used to credit people simply for uploading the plan to a forum on the internet. Which is not quite the same thing. This will change soon. Probably.
This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.
© Outerzone, 2011-2021.
All content is free to download for personal use.
For non-personal use and/or publication: plans, photos, excerpts, links etc may be used, provided that full and clear credit is given to Outerzone with appropriate and specific direction to the original content i.e. a direct hyperlink back to the Outerzone source page.
Unauthorized use and/or duplication of this material without express and written permission from this site's owner is strictly prohibited. If we discover that content is being stolen, we will consider filing a formal DMCA notice.