RAF SE5a (oz793)

About this Plan

RAF SE5a. Free flight scale model for .5 - .8 cc power by Doug McHard, from Aeromodeller December 1957. Wingspan 27 in. Scale is 1/12.

Quote: "The free-flight scale plan given away with this issue, and the Famous Biplanes solid model description which occupies our centre pages reflect the result of the longest, most involved research ever undertaken by us on the subject of one type of aircraft. Four contributors, three of our staff and many renowned authorities were responsible for what we consider to be the first-ever accurate plans of the famous SE5a, and both George Cox and Doug McHard are to be congratulated for two excellent drawings.

We do not have to emphasise the fine flying characteristics of Doug McHard's scale model for .8 cc. Its fame is already renowned following displays at the RAF Championships and the All-Britain Rally, where for realism in flight and excellent scale detail it was the top free-flight model in Concours d'Elegance and a source of admiration from all. The copius detail on the plan with stage by stage illustrations should enable any modeller with a little experience to duplicate the excellent performance of the prototype."

Quote: "A 1 inch to 1 foot free flight scale model of Major 'Mick' Mannock's machine as flown in 74 squadron RFC. Designed by JD McHard for .5 cc to .8 cc engines.

Before starting any assembly, carefully mark and cut out all fuselage parts. Cement wire fittings and 3/32 x 3/32 cross pieces to formers where indicated on plan. Bend wire for struts and undercarriage.

Start assembly of fuselage by binding with fuse wire and soldering together the undercarriage and front cabane struts. Ths unit is now bound securely to the front (ply) face of bulkhead 3. Coat with cement and block up with 1/8 in diameter binding holes to prevent fule seepage from the engine bearers. Align carefullly and cement firnly. Bind rear cabane struts to engine bearers (see plan view) then cement bulkhead 4 in position. This stage of assembly is shown in Photo 1.

The 3/32 medium grade sheet balsa fuselage sides should be carefully scored at bulkhead station 8 and bent slightly inwards aft of this point (see plan view). Coat the crack thoroughly with cement inside and outside, and allow to dry before proceeding further.

Cement to the inside surface of each side the 3/32 sheet reinforcement between bulkhead positions 1 and 2 and at lower wing attachment point (see side view). Cement the already assembled bulkheads to the starboard fuselage side and affix bulkheads 7 to 12 and lower wing attachment tubes as shown in Photo 2.

Attach port fuselage side, lower nose reinforcement, nose block, tailblock, tailskid and bulkhead 6. This stage is illustrated in Photo 3. Now cement the 1/8 x 1/16 stringers to rear fuselage, Photo 4. Cut away the stringers immediately behind the cockpit so that the rear edge of the 1/16 nose sheeting lies flush with the stringer surface (see side view). Cover fuselage decking ahead of cockpit with softish 1/16 sheet balsa one side at a time.

Moisten the outside surface of the sheet before cementing in place, this will pre-curve the balsa and considerably simplify the operation, see Photo 5.

Cover underside of fuselage with soft sheet balsa with grain running across the fuselage, Photo 6.

The removable top engine cowling is next built. Using the two 1/8 dowels in the top nose block plug this into the lower nose block cement the 1/4 in balsa bulkhead 1A to the rear of the nose block, cement the two 3/32 square hard balsa reinforcing strips to bulkhead 1A and to these strips attach bulkheads 2A and 3A. Bulkhead 2A should have the 20 swg retaining hook already fitted and cemented in place. Now cover the top of the cowling with medium sheet balsa, pre-bending as previously described for the cockpit decking.

When dry, remove the top cowling which should now appear as in Photo 7. This photograph also shows the engine in position, in this case an Allbon Merlin. Note the needle valve hole which must be cut to suit the particular engine chosen. The engine thrust-line should be corrected for sidethrust at this stage and the mounting bolt holes drilled in the bearers. After checking remove motor until model is complete and fuel proofed.

Tailplane: Cut out the tailplane, fin and rudder from soft balsa. The stabiliser is too broad to be cut from the standard 3-in wide sheet and the join should be made along the leading edge using a strip of hard balsa ahead of the joint. Cement former 13 (m/m ply) to the recess in the tailplane leading edge and cement the 1/8. hardwood locating dowel in place. Cement the 20 swg tail unit fixing hooks to the upper surface of the stabiliser trailing edge (see side view). Cement fin and rudder to stabiliser upper surface and square up with the soft balsa fairing blocks at each side. Make certain the rudder is upright. To the underside of the stabiliser cement the 1/8 sheet balsa locating piece making certain that the rudder is truly straight fore and aft. Cement the celluloid rigging washers to the tailplane in positions shown. A dotted line on the plan indicates the true scale stabiliser outline. The model will fly with a true scale stabiliser but is more sensitive and needs very carefully trimming.

Top Wing Centre Section: Next bind with fuse wire and solder, the 18 swg tubes to the upper ends of the cabane struts. Place the fuselage exactly over the side view on the plan and make certain the ends of the tubes come in the correct position as shown, before proceeding further. Make adjustments if necessary. Sight the tubes from the front to ensure that they are both in line.

The upper wing centre section is now built flat on the plan. Do not cement the M/M ply facing ribs to the structure at this stage. When dry remove from plan, and secure to fuselage cabane struts (see note and exploded view on plan). Cement the rigging hooks firmly in position.

The strut fairings should be sanded to a streamline section and bound and cemented in position then double covered with lightweight Modelspan cemented on, Photo 8.

Undercarriage: The main undercarriage leg fairings are bound to the leg from, top to bottom with strong thread and then covered with Modelspan. They are not cemented to the fuselage at the top end. The rear undercarriage struts are made up, the lower ends threaded over the axles and the top ends allowed to travel freely back and forth in the slots cut in the 1/16 sheet under-fuselage covering. Spring the spreader bar into place.

Wings: The upper and lower wings are identical except for the roots of the lower panels which have an extra rib and are cut away at the trailing edge, this is clearly shown on the plan. Incidentally, if you are a very strict scale fan, this last rib space should have no dihedral, however this is almost unnoticeable in practice, and the extra complication involved in construction was not considered worthwhile on this essentially straight-forward model. The only other differences between the upper and lower wing panels lies in the 20 swg strut fixings and rigging hooks. The positioning of these is clearly shown on the plan.

Before commencing wing construction cut all spars to correct size and bind the 18 swg wing attachment wires in position. Shape the leading and trailing edges to correct sections and cut the rib notches in them where indicated.

Pin down the trailing edges and hold the spars in correct position with pins on either side. Now cement the ribs in place and then attach the leading edge. The soft balsa sheet tips should be ,fitted but the necessary carving to section should be left until the structure is lifted from the plan. When dry the remaining wire fittings should be bound in place and the wings sanded smooth with very fine sandpaper.

The wing interplane struts are now made. They should be a sliding fit over the 20 swg wing fittings.

Assembly and Rigging: Assemble the wings and struts. The wing root attachment wires should be a smooth sliding fit in their tubes and they should be adjusted to give 1 in dihedral under each wingtip.

The rigging 'wires' are reproduced with grey, shirring elastic thread and four pieces are required each 14 in long and fitted with small 20 swg rings at each end. One length of elastic thread is taken from the front rigging hook 3 in. out from the root of the upper wing, down and around the top of the main undercarriage leg and up to the top of the front interplane strut. The elastic is taken outside the struts and thus prevents them from falling off. From the top of the front strut the rigging goes down to the bottom end of the rear strut and terminates at the rigging hook near the rear cabane strut.

The second rigging thread starts at the front cabane strut hook and terminates at the rear rigging hook on the top wing underside after passing around the interplane struts and over the fuselage rigging hook. This completes the rigging on one side, the reverse procedure is followed for the opposite side.

Cover all surfaces with single weight Modelspan, give one coat of clear and two of coloured dope.

Details: Fit wheels, radiator strips, engine cylinder blocks and gun. The two exhaust pipes are made from 1/4 sq balsa sanded to circular section and covered with Modelspan. They are attached by cementing and binding to the cabane struts. They are not cemented to the engine cylinder blocks.

Add roundels and insignia and fuel proof the entire aircraft, paying particular attention to the engine compartment and the nose generally. All-up weight should be between 8 and 9 ounces.

The model should balance horizontally when supported on the fingertips under the top wing centre section at the point shown on the plan. If necessary add weight to nose or tail until correct balance is achieved.

Glide test over long grass under calm conditions, launch level at model's flying speed, into wind, and note the descent. If the model dives, add weight to tail. If it climbs first and then dives; add weight to nose, until a steady controlled glide results.

First power flight should be made with the engine running very slowly, gradually build up revs making any necessary thrust line adjustments on the way to correct turning or erratic power flight, until the model safely handles full power. Trim for a large radius left-hand turn under power by adjusting the engine side thrust. The rudder may be warped slightly right to keep the nose up in sharp left turns under. power. Never turn the rudder over to the left and DON'T try right-hand circuits under power until you know the model's characteristics!"

Update 24/12/2022: Replaced this plan with a clearer copy, thanks to brokenenglish.

Update 2/6/2023: Added later article from Flying Scale Models, November 2002, thanks to RFJ. This includes some good colour photos of Doug McHard's second build of the SE5a model, almost 50 years later [pics 008-010]. The article text seems to be a direct reprint.

Supplementary file notes

Planfile includes article.
Later article (Nov 2002).

Corrections?

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