Spooky (oz4496)

About this Plan

Spooky. A 31 inch flying wing for 0.049 engines and two function radio. Uses a Jedelsky-wing construction.

The Keil Kraft Spook (oz4439) chuck glider design (by Bill Dean) dates back to 1947. This here is a later redrawn version at 31 in wingspan, for RC with a Cox pusher engine and 2 channels.

Direct submission to Outerzone.

Update 18/7/2023: Added article, thanks to RFJ.

Quote: "Maximum fun, minimum cost - build this flying wing and carve up the sky - it only needs inexpensive 2 channel radio and an .049 engine. Spooky, by David Boddington.

t was that man Swailes again. Hey Dave, remember that KK chuck glider call the Spook - wouldn't it make a great R/C fun model if it was enlarged?' What does he think I'm, Mr Memory Man, the design was current in the 1950's! But I wasn't going to get away with it that easy, he'd managed to find an original drawing of this little 'wing thing'. OK Ken, when I've got a few minutes to spare I'll take a look at it.

Of course, as soon as I took a peep at the Spook I was hooked, the mind went into overdrive and mental pictures of the model wheeling around the sky rapidly took over. Yes! Twice the size, a three dimensional fuselage, my avourite Jedelsky wing, a Cox Black Widow screwed on the back, el-cheapo two function radio and you would have a real fun machine. That was Sunday evening. On Monday I handed the drawing to Ken and we were test flying the Spooky on Friday - a bit late but I was at Model Technics on the Thursday!

Assuming your copy of AMI gets to you on Wednesday or Thursday, you should be airborne with Spooky on Sunday. The design ended up at 2-1/2 times the original 12-1/2 in span and this has proved to be an ideal size for the .049 engine power.

You don't need to use sophisticated radio equipment, a simple sliding tray system for the aileron servo provides the elevon control. You could use standard size servos but we used the J Perkins' Mini BB Servo and their Micro JR version (see Shop Talk January issue) allied to a Hitec 27MHz receiver and Tx and a 200 MAH battery. We are pleased to report that they all worked fine, the servo-response was very lively and in keeping with this little model. Total weight of the model was only [text missing].

The Jedelsky wing, with a slight taper on the trailing edge, gives a certain amount of reflex but this, with the elevons up, proved to be insufficient and Ken did some on-site butchery to increase the tip reflex, in common with the original HLG. Once this mod had been carried out, and the C of G moved delicately back, the Spooky was up and away.

Construction: Start with building the fuselage, first arranging the location of the radio equipment, you won't need the battery at the front, try to leave the options open to allow the correct balance to be achieved without having to add ballast.

Fixing a Cox 049 engine to the rear former (laminated for good screw retention) is the easiest option but alternative engine bearers are shown in case you want to fit a Mills .75, PAW 80 or similar. In this case, the fuel tank could go between formers F5 and FO.

Construction of the fuselage could hardly be more simple but do ensure that the aileron servo slide (if fitted) is moving smoothly, it consists of a plywood tray with 16g brass tubes bound and epoxied to the top edges. This slides on two ltig pianowire rods fixed to Jormers F4 and F5, the elevator servo moves it forwards or backwards. Round off the top front and lower corners, the hatch is held by a plywood tongue at the front and the wing dowel, with a small rubber band, at the rear. All done? Right, on to the wings.

A nice light quarter grain balsawood is ideal for the wings and start off by using a lightweight filler on the underside of the sheets (it is almost impossible to treat this area when the ribs are in position). Build the left and right hand full panels, note the grain of the 3/32 rear sheet is parallel to the aileron, the root ribs and ribs inboard of the fin are set at the dihedral angle and the penultimate root rib is glued in position after the wing is banded onto the fuselage. Pin down the ribs, add the sheet, using a PVA glue and leave to set. Note that all ribs are the same length at this stage.

When set, remove from the building board, shape and sand the leading edge, trim the rib ends (and plane away some of the surplus to the tip ribs) and join, the panels by supporting the fin ribs by 1 inch. Trim the centre leading edge triangle, check the fit on the fuselage, add the ribs to fit clear of the sides and reinforce the rib joint with nylon and PVA.

Cut away the ailerons, these can be hinged using fabric patches, thread or strong adhesive tape. The tips outboard of the tin have no dihedral and the rear section, as shown on the drawings, are turned up to give a reflex. Cut the tops away outboard of the fin, leave a spigot to project through the fin, but cut away the portions shown shaded. Make up the fins from balsawood/0.4mm plywood laminations, and sand well.

Glue the fins in position, upright, and cut and bend the rear of the tip to the reflex shown. Mark and glue the 1/4 in triangular to the outside of the fin and then glue the tip in position..."

Supplementary file notes

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