MODEL AEROPLANE NOTES

Auckland Star, Volume LXX, Issue 23, 28 January 1939, Page 3 (Supplement)

MODEL AEROPLANE NOTES

PERI No. 1

A 36in Wing Span Cabin Monoplane With One-blade Propeller.

This medium-sized cabin monoplane, the Peri No. I, caught my eye recently, and is ;i fust-class nindi'l for those that

want a fuselage job of reasonable "» injrspan. y<'l not uettino' into ihe y.-ry liijrii orade. di Ilictil I-t o-bttild class. Us construction is straightforward and simjile. coi-t. of materials is low. and yet with ordinary workmanship it will 11 v and lIV well'. ' '

Tlio /ifst lli'mo- t<> do is 1 o draw ill 1 fiisi>];i;r<' side 1 i;i j>i- ii}i full t-i/.c (in a s|)itl'i' |iiecc of Imaiil aliiiul 2Sin by 4in. Sc(3 llial tliis luiard i-< wit 11 ■ > u t warp or twist and if vim can ;jot a. piece of s.ifL pirn; fur the job, so much the botier Mri tlic ] >ius can be pressed in and pulled out with much more ease. Incidentally, little tliinovi like this make the construction more pleasant. To help in 1 he drawing out I mi-lit state that plan is just about two-ninth full size and the ribs sections about three-i|uarter full size, but if you use the scale of inches shown on the drawing, von can "el all measurements accurately. Draw the win;.' up similarly and you are all >et to pi. Xow proceed to construct lii'st one fuselage ~iije i>ut ot one-ciolith si|iiaro balsa strips, tilling in the uprights and the diaiMmal brac<'s where

shown. " Note that the shapes of the top of the nose formers are not shown on plan, but are made of 1-10 balsa sheet and are made a nice oval outline to i!iv« the curvature on top of the nose. Those are not inserted till later on. Willi one side done and dry, proceed to build the second one right on top of the first, in this manner making sure both are exactly alike in outline. Balsa cement should be used on all joints, being applied by a match stick or a bit of 1-S square balsa sharpened to a taper point. When both are dry, remove from board and build up the fuselage ■skeleton bv inserting the horizontal cross braces, starting at the centre, using rubber bands to hold together as you work along and when ail are in place lilling i:i the bottom and sides in the first bay with 1-8 balsa sheet. Now lit the curved cross pieces 011 top of nose and fit the 1-32 sheet by pinning and cementing. Pins are all removed after cement is set. The undercarriage can now l>e fitted. It is made from 18 swg. wire, and where the rear leg joins the front one you can solder, but a simpler and quite effective method is to bind with 1-M> or 1-30 sq. rubber. This takes a wonderful grip, and is used on gas jobs quite often, so it will stand all that this model will give it. Hind and cement the top ends of the undercarriage to the under side of the fuselage and fit the wheels. Wheels should be not less than lAin diameter, and may be made of aluminium or wood. The noseblock shown is made of laminated 1-S sheet, but can be made from a solid block. Brass or aluminium tube to take ltiewg wire a running fit

is set in the noseblock with cement. Xote there i« no down thrust or side thrust, the hole being exactly in lino with the line shown. Fit the rear rubber hook firmly and also the tailwheel

tn blv. \ou are now ready for covering. In the meantime get on with the wing and tail surfaces. The win" l er y. simple, being a parallel with ribs of l-16in sheet spaced as shown. The leading edge U 1-S bv 3-16, trailing edge l-lt> by 3-lt> and "centre spars 1-S sq. each. Personally I would insert a 1-16 by 3-lti spar in the top of the rib also about one-tliird way back. Bamboo tips are u*ed, this being curved to shape over a gas flame. The rudder and elevator are simple units, the only catch being that the rudder has a hinge made of light strips of aluminium sheet about 2<i swg. being thick enough. Cover the whole of the surfaces with model aero tissue and gi\e a light coat of weak model aero dope.

The propeller is of the one-blade ivpe, being cut from the block size shown. The other end is carefully and accurately weighted with lead until the propeller balances perfectly. Anv accepted form of freewheeler can be fitted with advantage. This propeller is powered with 18 strands of 1-S flat rubber, lubricated well and abou- i

overlap, i.e.. the rubber motor is 25 per cent longer than the distance between the rubber hooks.

If it is found that a little downthrust helps the flying capabilities, this may be done by carving away the bottom of the nose block a iittle over 1-ltiin. For a field test, a match stick can be inserted between the top of the nose block and the first former of the fuselage.