JETEX PLANS - JETEX 200

VEROSONIC

example@example.com (Administrator) — Tue, 09 Mar 2021 09:48:29 GMT

Veron Verosonic. High performance sailplane. Building instructions. First, study the plan and identify all the parts on the printed sheets of balsa. Familiarise yourself with these and all other instructions. This design, if carefully built, is quite capable of consistent contest durations of three to four minutes in still air from a standard FAI line length of 328 feet. The only tools needed are small pliers, a few pinns, either steel backed razor blade or balsa knife, and fine sandpaper. The fuslage sides, wing and stabilizer panels and the fin are all built directly over the plan. Wings: Lay the plan on the building board and cover with waxed tissue or greaseproof paper to protect from the cement. Select two even grade lengths of 3/8 x 1/8 for spars. Lay over plan and mark in pencil the positions of all ribs. Taper spans on top edge to 1/4 x 1/8 at R11.

SKYJET 200

example@example.com (Administrator) — Tue, 09 Mar 2021 00:34:24 GMT

Keil Kraft Skyjet 200. Free flight sport model for Jetex 200 power.

ROCKET 'DELTA'

example@example.com (Administrator) — Thu, 04 Mar 2021 23:11:29 GMT

Free flight model for Jetex power.

LITTLE STINKER

example@example.com (Administrator) — Wed, 03 Mar 2021 09:39:35 GMT

Little Stinker. Free flight Jetex model. Winner of the 1950 'Jetex' competition. A study of this successful high performance contest design leaves no doubt that the designer is a lightweight enthusiast. His performance at Farlop under most adverse weather conditions amply proved the capabilities of this model, the flight times being 114.7 seconds and 122.7 seconds. In his opinion the following design requirements were necessary in order to obtain maximum performance with a Jetex model: 1. Ultra light weight; this being very necessary if a fast and high climb is desired. 2. Have a comparatively low centre of gravity, ie motor mounted under the fuselage. 3. Have a large tailplane area and moment arm to stop power looping and to give a good pull-out glide. Construction. Fuselage. Build this in the usual manner, ie lay down two sides, remove from plan and fit in formers together with spacers. Panel the nose pay (weight box) and cement on the roughly-shaped nose block, finishing this off when the cement has thoroughly dried.

GHOUL III

example@example.com (Administrator) — Sat, 20 Feb 2021 02:39:55 GMT

A 352 Sq ins Flying Wing for power units weighing up to 2.1 ounces EASY to fly, and simple to build, Ghoul III is the latest design by our well-known specialist contributor on tailless types - MM Gates. Why not try one for your baby class diesel or Jetex unit? Its high performance is equal to the best of orthodox designs. Construction. The wing centre sections are constructed by cutting out the ribs and cementing them to the I in. square spar, then add L.E.'s and T.E.'s which are first roughly shaped. Outer portions are made similarly. The centre section block is made from laminated sheet, shaped to give the correct dihedral. Only the inner ribs of the outer sections need be set to allow for dihedral. All five sections of the wing should be very carefully cemented together, and the joints gussetted as shown on the plan. Sew the rear undercarriage legs to the trailing edge and cement firmly. The nosewheel legs are pushed into the centre section. Cover with rag tissue, well doped and fuel proofed. Note that before covering, the washout will be insufficient, the tissue will induce further washout into the outer sections quite naturally. Final adjustments should he made to the washout after doping; but before fuel-proofing. Fins and elevons should be cut from lightweight 1/16 in sheet and added after covering. Care must be taken in setting both elevons to the same angle. The method of pylon construction will depend on the motor to be used. This may be anything from a Jetex 200 to an Elfin 1.49.

BOULTON-PAUL P111A

example@example.com (Administrator) — Wed, 27 Jan 2021 08:18:31 GMT

One of the earliest deltas, the P.111A has always attracted modellers with its clean lines, stubby fuselage and general pert appearance. Besides stubbiness, the body also features from the modellers point of view a capacious interior and easy curves which lend themselves to moulded sheet constuction. DP Golding has taken full advantage of these points in this neat and smooth-flying scale model. Construction commences by carving a solid block fuselage (preferably from obechi); this is the only 'awkward' stage of the construction, but it is essential for true scale appearance. The block is carved 1/32 in undersize overall, smoothed and given one coat of clear dope. Four sheets of fairly soft 1/32 balsa are required, and one of these should be soaked in hot water for about ten minutes. After shaking or wiping off the surplus, lay one edge on the fuselage block centre line and bind tightly with 1/4 in rubber. Where wrinkles occur (probably two at each end) cut and allow to overlap, butt-joining when dry. The corresponding quarter should be made in the same way and, when dry butt-joined to the first piece, replacing the complete half-shell on the former and binding in place. Steam in front of a kettle for a couple of minutes and allow to dry before removing and laying aside. The bottom half repeats the process, and two 1/32 x 1/4 strips are cemented along the edges to facilitate jointing. Rubber marks, etc., will sand away quite easily. Construct all formers and fit in F1-5, the lower halves of F12-15, and F16, followed by the motor mount. Add top halves of F12 and 15, and F7-11 and install the augmenter tube which must be accurately lined up and will need approximately 3 in cut off the end. Build fin, etc., and fair in place and make parachute housing, which is added after completion of the fuselage. Fit and align top shell and cement in place. Silk cover the lower half up to just above the join and cover the top with rag tissue.

ZEPHYR

example@example.com (Administrator) — Mon, 04 Jan 2021 22:17:26 GMT

Reprinted from Aeromodeller, June 1948, pp. 354-356 Zephyr Fuselage. This is a simple slab sider. Build the two sides on the drawing. Next, cut the-temporary bulkheads of 1/8th sheet balsa and hold them in place between the fuselage sides with pins at No. 3 and No. 6 cross strut positions. Cement the rear ends of the fuselage sides together, then No. I top and bottom crosspieces. When this has been done the fuselage sides will take a natural curve from nose to tail and the remaining cross struts can be fitted. When all are in place and the cement has set, remove the temporary bulkheads and fit normal cross struts. Next, fit the crosspieces and celluloid tubing for the wing attachment pins and undercarriage struts, and finally the wing seating on which the centre section rests. Mainplane. This is in three sections, right, left and centre section, cemented together and reinforced at the joints by a hard balsa bridge piece cemented to the rear face of the main spar, and a 20 gauge steel wire strip cemented and bound with tissue to the front face of the trailing edge. Tailplane. Build the tailplane on the drawing, as the leading edge if of 1/8th and- the trailing edge of 1/16th balsa, place strips of 1/32 sheet balsa between the drawing and the under- side of the trailing edge to raise it to the correct position. Zephyr Fin and Rudder. The fin and rudder are joined by two small sheet brass strips. Build and cover the two units as one, cut through the tissue after doping between trailing edge of fin and leading edge of rudder to allow for rudder adjustment. Flying. Trim the model for gliding with the Jetex unit unloaded. The extra weight of the loaded unit and slight down thrust counteracts the tendency to climb too steeply under power. Fine adjustment of downthrust can be obtained by placing thin washers between the Jetex base and the under- side of the fuselage.

TWIZZLER

example@example.com (Administrator) — Mon, 04 Jan 2021 22:03:00 GMT

Reprinted from Aeromodeller, November 1951 (p. 593) For a near-vertical climb with Jetex 200, try Dick Twomey's latest, the Twizzler – an easy to build, easy to fly, high performance JETEX model, 28 inch span, with detachable wing, designed for competition work with the JETEX 200. CONVINCED that the high thrust line layout is the best for Jetex duration, Dick Twomey has developed the "Twizzler" (a name born recently in the excited broadcast commentary of the Supermarine Attacker upward roll at the "Daily Express" Air Show) from his renowned "Firecrest" design. He has found a simple way of doubling the power, while halving the engine run, which is perfect for open ratio competitions. The climb of the "Twizzler" is thus stepped up to over a 60 degree angle, and recently it established the best ratio in a power contest with a 3 min. 27-56 sec. flight giving a ratio of 20-5 : 1. The chief differences between this and other Twomey designs are reduced drag, with a slimmer fuselage, less fin area, faster wing section, enlarged tailplane with dihedral tips, light weight, and the off-set Jetex unit. Last year's model won the R.A.F. Championships, and "Twizzler" is undoubtedly an improved version. Study the designer's trimming gen on the plan [also reprinted below] for his novel system of boosting Jetex power. CONSTRUCTION Fuselage. Cut two fuselage sides from 1/16 in, sheet (medium) join them with former A and add 1/16 in. cross spacers. Cut away as shown for wing, which slides into position in one piece. Add ply Jetex platform, formers B and C, noseblock fin and rudder. Sand finished fuselage all over. Wings. Build whole wing in one piece, flat on the plan. Then crack at dihedral points, prop up to required heights and cement dihedral gussets in place. (A "turbulator" was tried on the original model, but has been discarded as having no beneficial effect on such a small model.) Tailplane. Simply constructed and must be kept free of unnecessary weight. Do not neglect to build in 1 in. dihedral under each tip as shown on the plan. Failure to do so would have grave effects on stability. Jetex Mounting. Offset the unit 10 degrees to starboard, as shown. Then by "balancing" rudder against motor sidethrust you can achieve the best and most safe trim, a straight steep climb followed by a left-circling glide.—Happy "Twizzling"! TRIMMMING With c.g. in position shown test glide with Jetex unit empty until satisfactory left circle is achieved. All alterations to glide trim are made by giving positive or negative incidence to tailplane. Do not touch thrust line or wing incidence. Now cut one 200 charge in two and try power flight. Make alterations to rudder to obtain straight stable climb. Note that rudder alterations may also entail tailplane alteration (the tighter the turn, the more negative incidence required to keep nose up). Increase power by inserting two 200 charges but not launching until the first has completely burnt out and the second charge is under way. Trim until this is satisfactory. For final power trials cut down the diameter of a 350 charge until it just fits. You can thus fit two 350 fuel capsules into the 200 unit and the result is astonishing. Complete engine run will now be 10-15 secs with a corresponding increase in power. Length of engine run depends on how much air gap there is between the fuel and the inside cylinder walls of the unit. The less close the fit the more the power and the shorter the power run. Warning:- With the 350 fuel the Jetex metal end cap will not last forever and also the asbestos washers must be continuously replaced.

STILETTO

example@example.com (Administrator) — Mon, 04 Jan 2021 21:45:02 GMT

Reprinted from Model Aircraft, May 1954 (p. 184) A contest model for the Jetex 200 by one of the experts STILETTO is the latest in a line of models designed for the Jetex 200, and developed from the original Firecrest, which won the first I.C.I. Challenge Trophy contest in 1949 with a 20 : 1 ratio. Stiletto Since then the tendency has been towards lighter construction, reduced wing area, and smaller fuselage cross-section: so that the biggest asset of present-day Jetex models is a steep, fast climb. Stiletto belongs to this school of thought, and must be trimmed accordingly. It is able to stay in a fast straight climb, and will gain maximum height in this way. High-thrustline is the ideal set-up for this trim, while under-slung jet units generally characterise the " spiral-climb " type of model. The original model was lost after an 8-minute flight (on one pellet). It had previously qualified for the I.C.I. Finals with 3 : 55 o.0.s. on 14 secs. fizz (ratio 16 : 8). The second Stiletto built gained fourth place in the 1953 I.C.I. Trophy, with a ratio of 9 : 07; and anyone who attended the All-Britain Rally can remember that weather conditions were not ideal. It is of vital importance to go easy when trimming, starting with only 4-5 sec. of fizz. If the least tendency to turn under power is apparent, do not fail to make a correction before the next attempt. Anyone who has flown contest Jetex models (or only watched them) knows that they are even more prone to spiral power dives than prop-powered planes. With reaction propulsion, variations of thrust are common, and such variations will cause inconsistencies in airspeed fatal to a circling model. Moral: keep straight! Then it will be safe to say "the faster the better" … and the resulting climb will certainly satisfy you. Fuselage The fuselage section takes the form of an inverted triangle: i.e. the "base" is at the top, and the "apex" forms a keel at the bottom. The fuselage is built upside-down, the "base" being built first, on the plan. (See fuselage top elevation.) After the spacers have set, the first five inches of this are curved upwards, till the point of the nose is 11/16 in. from the building-board. Now the formers can be added, and the underfin also, after the 3/32 in. keel has been cemented in place. After the fuselage has been lifted from the plan, add pylon centre-post, cementing it firmly to the keel. Then pylon front and rear edges can be added, and top also. Eventually all spacers can be added, and Jetex mounting clip screwed into place. Check that thrust-line is as shown on plan. Note: If the builder has not had too much experience with Jetex models, it is recommended to build the pylon unit separately, and make it "knock-off" in the event of a power dive. However, if you consider yourself able to trim without such diversions, it is well worthwhile to make the pylon integral with the fuselage, as this will be lighter. Add small fin as d/t stop, and 1/8 in. sheet to give correct tailplane incidence as shown – add also 1 mm. ply platform for tailplane. Cover with lightweight Modelspan, and add two coats of clear dope. Total weight should be 0.4 oz. Wings These must be constructed with care, as weight has to be cut to a minimum. Ensure that T.E. is of hard 1/16 in. sheet. Build whole wing on plan, leaving out top spar and bracing struts at first. All "oblique" ribs are of 1/32 in. sheet, while "straight" ones are of 1/16 in. sheet. Tips only have dihedral, so these are cracked up to the required angle. Be careful not to let the dihedral "creep" to a greater amount than that shown on the plan: more than ¼ in. extra could be dangerous to performance. When dihedral has set, add top spar and forward bracing struts. Give wing adequate time to set firmly, having ensured … of course … that the building-board is dead flat. Cover with light Modelspan, add two coats of clear dope on top, one coat below. Check dihedral does not change, nor warps appear, while dope is drying. Same applies to tail. Wing weight 0.4 oz. Tail This is built on plan, dihedralled as shown. Add pins as shown, for operation of tip-up d/t. Cover with light Modelspan, one coat of dope top and bottom. Weight 0.2 oz.

FIRECREST

example@example.com (Administrator) — Mon, 04 Jan 2021 13:25:32 GMT

Reprinted from Model Aviation (UK), Feb. 1950 (p. 20) FIRECREST is one of the few Jetex-powered models which has not followed conventional lines – that is, the high wing, pod-and-boom type with the underslung jet unit mounted in the rear of the pod. With all such layouts the line of thrust is very much below the centre of drag of the whole model, often with the result that the model is actually underelevated to prevent stalling under power. With the jet unit mounted just above the wings the line of thrust coincides, or very nearly so, with the centre of resistance so that optimum trim can be obtained both under power and on the glide. This then enables a very efficient rigging to be adopted, where the centre of gravity is moved well aft so that the tailplane is carrying part of the total load. Naturally enough, the tailplane itself is of lifting section. Winners, 1949 ICI Jetex Trophy For the wings, a Marquardt type aerofoil section was chosen as this has proved ideal for small, lightly loaded models, combining low drag for best climb with excellent glide characteristics at lower speeds. The Firecrest, in other words, is designed along best modern duration lines and as such has a flight ratio comparable with that of most free flight power models on limited motor runs. The final design which won the I.C.I. Trophy differs from the original prototype. One of the main differences is that an underslung fin is used. The first model also had an upper fin of almost the same area, but this was not found necessary as adequate directional and spiral stability is achieved with just the bottom fin alone. Constructionally, the Firecrest should present no difficulties to the average builder. The fuselage sides are cut from sheet and joined with 1/16" square spacers and a 1/16" sheet former (former A), as shown in the detailed sketches. The original model used hard 1/32" sheet for the sides, but light 1/16" sheet is preferable, and can work out at about the same weight, if carefully selected. Thinner sheet has a tendency to buckle or warp. To mount the Jetex 200 unit, the standard clip is screwed to a 1 mm. ply base, which is then cemented across the top of the fuselage immediately behind former C. The span between former B and the noseblock is filled in with soft balsa block. The cockpit cover is cut down from a standard commercial bubble type canopy, reversed back to front. To take landing loads, sheet in the first bay of the underside of the fuselage. The remainder of the top and bottom surfaces of the fuselage are then tissue covered and the whole given one coat of dope. Construction of the wings and tailplane is straightforward. The wings are built flat in one piece and later cracked up to the required dihedral angles. Joints are strengthened by cementing the 1 mm. ply W1 and W2 members to the spars. The Firecrest is best flown in a wide circling glide after a straight climb. Trim for glide first, having balanced the model at the design C.G. position, and add negative incidence to the tailplane, if necessary, to get the flattest glide. Try power tests with a quarter-charge, i.e. one half of a single charge. Any tendency to turn under power can be corrected with rudder, or by offsetting the Jetex unit, or a combination of both.