Designer Techniques No. 19

Hawker Tempest Mk V Series II

by Gareth Logan - Summer 2000

 

I have built and flown a variety of PSS types in recent times, and like many began with an Andy Conway Hawk.  This was swiftly followed by the Jim Strain Victor and a Ron Collins Mustang.  All excellent choices for all conditions.  At some point along the way discussions came round to the somewhat challenging prospect of trying a P-47D Thunderbolt.  John Plumbley had already successfully used Brian Taylors' plans for a largish FW-190 and enquiries soon established that a suitably sized plan was available for the P-47.  Both John and I decided to go for it, and were excited by the prospect of a fine pair of Jugs on the slope. (I've often admired the Jugs at events around the country myself!! Ed.)

The success of the 'Jugs' as a subject for PSS is now well known, and despite their apparent bulk and blunt front-ends, they are an absolute delight to fly.   After some happy times with the P­47, I looked around for another subject and became taken with the Tempest V.  Although a similar size to the P-47, the Tempest is somewhat more streamlined and has a more slender fuselage.  This had to be a winner I thought, and so proceeded to order the said plan, cowl and canopy from Brian Taylor.

So, what is the Tempest V all about...........?

Gareth Logans' Tempest V is launched at the Hole of Horcum event - April 2000

The plan notes show that the prototype model (c.1973?) weighed in at a healthy 9 1/4 lb. which included 3/4 lb. of nose ballast.  The designer states that with care, particularly at the tail­end, an all-up weight of 8 1 /2 lb. can be achieved.  Given the intentions to slope-soar the model I considered that even at 8 1 /2 lb. it would be too heavy.  I therefore needed to save as much weight as possible and by building carefully was aiming (or hoping!) for something like a finished weight of 6 or 7 lb.

The construction method is very similar to that on the P-47D Thunderbolt, also based on a Brian Taylor plan.  The fuselage is built with a central box, around which formers are set to produce an accurate scale outline.  The box consists of 1/4" solid balsa sheet at the front and extreme rear, each end being connected by an open ladder type structure built from 1 -4" square balsa.  AIthough the model would not be subjected to the stresses and vibration produced by a 'big noisy thing' at the front, I was wary of building too lightly, as we all know - slope landings can be somewhat abrupt affairs at the best of times.

All things being equal however, I considered that all the 1/4" sheet and square balsa used in the fuselage could safely be substituted with 3/16".  All the formers were left as 1/8" sheet, but most were hollowed extensively.

The fin and tailplane are all built up as per the plan, and again all ribs were lightened by cutting suitably sized holes in them.  All the tail-end is sheeted in 1/16" balsa.  The elevator on the plan uses solid balsa so this was substituted with a lightly built-up affair.  A working rudder was considered unnecessary, so this was built as part of the fin.  Omitting rudder hinging, control links and associated strong points helps in a small way to keep tail-end weight down. The omission of the steerable tail wheel (or any wheel!) must also have contributed greatly to the weight saving.

The fuselage was partly planked to ensure a degree of rigidity whilst work progressed on the wing seat areas.  A change in wing section was considered essential and the fairly thick semi-symmetrical original was replaced by E205, and the wing incidence was kept the same.  

Before progressing further I now had to construct the wing in order to achieve a good fit on the fuselage, and to assist in finalising the method of mounting.  The plan shows metal retaining brackets at the leading edge and two substantial bolts at the rear.  I decided to adopt a standard kipper type method of a dowel peg at the front of the wing and a single nylon bolt at the rear.

Building the wing over the plan using the flat-bottomed E205 ribs proved straight forward apart from some fun with the outer-panel dihedral.  The wing is built in three parts, a flat centre panel and separate outer panels which are glued on at the appropriate angle.  A dihedral joint template is shown on the plan so this was used, but I had to take into account the thinner wing when measuring the dihedral at the wing tip.  At one point the wings were beginning to resemble a Gentle Lady before I managed to sort out what I believed to be the correct angle.

Inboard lower trailing-edge flaps were omitted for simplicity and to reduce weight.  The ribs on the outer panels were also hollowed-out for the same reason.  Brian Taylor plans often show scale-like aileron arrangements in terms of hinging.  I followed the plan in this respect to achieve a reasonably neat setup using brass tube and piano-wire to provide hinging at each end of the aileron.  I decided to extend the ailerons inboard by one rib, as this slight deviation from scale is not too noticeable but would hopefully improve control authority.

Whilst working on the wings, the natural interruptions required for glue to set etc. were used to begin thinking about the cockpit area.  My interest in the Tempest had prompted me to acquire a reprint of the official 'Pilot's Notes', and these showed the instrument layout to good effect.  I used the tried, tested and simple method of white plastic card cut to the shape of the instrument panels and painted matt black.  The instruments details were scratched out of the matt-black using a scalpel blade, allowing the white plastic to show through in a rough representation of the various dials and switches.  A simple balsa bucket-type seat for the 1/8" scale Pete's Pilot was made up and fitted, and the rest of the cockpit made up using bits of scrap balsa.  The fuselage planking around the cockpit area was then finished.  I probably completed these details in only 2 or 3 hours and was quite pleased with the result.  A sliding canopy was achieved by using small square-section plastic tube with slots let-in lengthways to form square 'C' section rails which are attached to the cockpit sides.  The canopy was fitted with pieces of plastic "H" section which run in the square 'C' channels.

Being somewhat lazy and far from a perfectionist I tend to favour a representation of a cockpit rather than a faithful reproduction, particularly as much remains hidden from view.  I must admit that I get somewhat fed­up and can rarely go all out for 100% finding that my attention span wanes somewhat as 90% is reached. The last 10%always eludes me!

After completing the wings, the mounting points and lower fuselage areas were completed and the rest of the fuselage planking finished.

A fibreglass cowl was obtained with the plan and this proved to be a reasonably good fit on the completed fuselage.  In the absence of an engine and associated mountings, the fuselage central box was extended forwards within the cowl, and a suitably strong bulkhead fitted at the very front.  A hardwood spinner was turned by a friend and a 5mm. bolt let into the back.  This was used to secure the spinner through the front of the cowl into the front bulkhead, retaining the cowl in place at the same time.

It's always interesting at this point to stand back and view the assembled model and to consider the implications for balancing the aircraft.  After installing the elevator servo at the very front of the cowl and a single, central wing servo driving the ailerons, a battery pack and receiver was roughly positioned at the front.  Going for broke, I initially dumped some 12ozs. of lead up front and checked the balance point.  This was disappointingly rearwards and another 8oz. was finally required to bring things in line.

Covering a model is often a chore for me as I am always itching to finish the thing and see if it flies.  Having previously used Solartex and been disappointed to see it blister on hot sunny days, I plumped for a change.  After much debate on the merits and alleged simplicity of using white paper pasted on with diluted PVA, I took the plunge with some trepidation.  As things turned out the process was quite straight forward.  A light coat of sanding-sealer was applied and an approximation of panel lines drawn on the surfaces. The paper was cut to fit (more-or-less) these panels.  Thinned PVA was brushed onto the surface of the model one area at a time, quickly followed by the paper panel which was first dunked in water.  On applying the paper the wrinkles were smoothed out with a dry cloth dabbed on the surface.  Working methodically over the model probably didn't take much longer than it would have if I'd used an iron-on film.  It must be said however, that the final result did not inspire me, it just looked like what it was, loads of pieces of paper stuck on!  However, once a grey undercoat was applied the appearance was transformed and I began to look forward to the rest of the painting.  Humbrol enamels were sprayed on, using a colour scheme based on an aircraft from No.3 squadron circa. Jan. 1945.  Some aircraft at this time still retained invasion stripes on the lower surfaces, and I decided to apply said stripes to the underside to aid orientation in flight.

Being too mean to shell-out for decals I hand-painted the RAF roundels and squadron markings.  Interestingly, I was unable locally to find a suitable Humbrol  blue fur the roundels.   Some rummaging around in the shed followed, and I found an aerosol tin of Halfords Acrylic Rover Nautilus Blue which was roughly suitable, so this was used to good effect.

On completion of the painting some 'weathering' was added and a couple of light coats of Satin varnish was applied.  The balance point was not noticeably affected by the covering and painting, and it was then that I decided to weigh the finished model to find out how successful my weight­ saving efforts had been.  I was very pleased to find the weight to be comfortably under 6 lbs. and eagerly awaited an opportunity for a test flight.

The Hole of Horcum April meeting was only two weeks away and this proved to be the first opportunity to fly the model.  As they say, she flew straight off the board, albeit in less than stunning conditions.  A degree of caution had therefore to be exercised on this first outing, but it was readily apparent that the handling was every bit as satisfying as expected, with no real vices.  Of course, flying this size of model with wing loadings around 25oz. does mean that if you do something silly, the aircraft can lose a lot of height alarmingly quickly!  As long as a modicum of common sense prevails (yeah, right!) the Tempest is a delight to fly, almost like a big kipper.  Rolls are sweet, and although not as fast at the P-47, probably more scale- like as a result.  Particularly impressive are those low-level passes across the slope where the Tempest seems to be most realistic, representing it's role as a low to medium level fighter.  Typical of a model of this size, I think that the weight and shear presence contribute to a very solid looking aircraft and I can't wait to get her out in better conditions.

I consider myself a very much average builder and am adept at hiding all manner of 'agricultural' construction beneath a sheet of 1/16th balsa.  It was very satisfying therefore to find that the model was so well regarded at the Hole of Horcum meeting, winning a much appreciated first place.  All in all, 1 have been most impressed with the Tempest, and would recommend this size of model and type of construction to anyone with a modicum of experience building and flying PSS.  

 

Wingspan: 61 1/2"
1/8th. Scale.
Fully built-up construction.


Planked fuselage and sheeted
wings -
Eppler 205 wing section


DESIGNED BY BRIAN TAYLOR for 10cc. ENGINES.

 

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