The 1930s saw a number of well-funded Australian aviation organisations scrabbling around for business. Aviation historian Keith Meggs checks out a hornet and a moth project that didn’t get off the ground for long.
The Hornet Aero engine came about as the result of discussions between Don Harkness, managing director of Harkness & Hillier Engineering Company at Parramatta Rd, Five Dock (Syd), and Edgar Wikner Percival (later to found Percival Aircraft in England) as to the desirability of a more powerful engine being available for current light aircraft. The limit then was of the order of 60-70hp, and it was felt that at least 100hp could be utilised in the immediate future.
The company had been associated with automobile and aircraft work for a considerable period, had made blocks and heads for Brockway bus engines, the complete Australian VI car, after taking over the original manufacturer’s factory, replacement rings and pistons for the Sunbeam Dyaks in AA&ECo and QANTAS Avro 504K’s, and considerable overhaul and reconditioning work on various aircraft and engines, dating from work on one of the imported Blériot XI’s, on W.E. Hart’s Gnome rotary, and on ‘Wizard’ Stone’s Queen monoplane. Harkness was a well-known racing-car driver and was the first man to drive at over 100mph in Australia, on 17 October 1925, when he achieved 108mph.
Some correspondence was carried out with Larkin during the manufacture of the Lascoter and Lascondor, after Larkin had asked about the possibility of engines being manufactured for these types, but with no result.
Following the discussions with Percival, Harkness spent some 12 months of spare time in the design of a four-cylinder air-cooled in-line engine as a private venture. Detail drawings and pattern making were completed in about another six months, and casting of the crankcase, cylinder block and head, sump (all of aluminium), and manifolds, sufficient for two engines, was then undertaken. From company stocks of Hispano-Suiza parts, aluminium pistons, gudgeon pins, rear vertical shafts, camshafts, and camshaft bearings were used. The cylinder block was cast integrally with the crankcase, with cooling fins incorporated, and steel liners were inserted into the bores. Design and manufacture of a number of special tools, to carry out operations which others had declared to be impossible, was successfully carried out during manufacture of the engine.
Forgings for the crankshaft and connecting rods were a problem, until Sir Keith Smith (who, with his brother Ross, flew the Vickers Vimy from England to Australia in November-December 1919), as Australian representative of Vickers, became interested in the engine, and eventually had them done in England for the prototype, for which they were supplied free of charge. They were delivered within three months, and machining commenced immediately, so that, after heat treatment at the Lithgow Small Arms Factory, final assembly of the engine was completed by about mid-June 1929, when it was reported that it would be going to the RAAF Experimental Section at Randwick for testing within a few days, based on enquiries and discussions of some months previously. However, difficulties were encountered in arranging for such work to be accepted when the time came.
A syndicate had been formed in about January 1929 to finance development and marketing of the engine, and, after completion of the prototype, Harkness visited Melbourne to arrange for Type Testing. He tried unsuccessfully on five occasions to see Col Brinsmead, but discussion then with Air Cdre Williams resulted in final approval to have the testing carried out at Randwick, at Harkness & Hillier expense, and with the use of company labour, because of the impending closure of the Section. However, it was stated that CAB would not accept test results for civil certification.
An initial test run for about one hour was made, followed by a power check with a propeller which would absorb 80hp. This showed that it would comfortably exceed that figure, and subsequently a larger propeller absorbed 110hp at 2,000rpm. Late in July, Brinsmead denied any responsibility for test delays, and stated that CAB had been doing its best to make suitable arrangements — on 6 August it was announced that CAB was sending a representative from Melbourne to Sydney to go fully into the question of Hornet testing. A statement emanating from an RAAF officer at Randwick on the following day proclaimed that no engine could have given better results during preliminary trials.
To conform with the Type Test requirements, it was necessary for it to be run on a dynamometer for 100 hours under supervision, and because of the difficulties of air cooling during early stages of the run at Randwick, a second engine fitted up for water cooling was built. Oil cooling was achieved by feeding the oil through a heat exchanger built around the induction manifold, and full-pressure lubrication was used.
An attempt was made to obtain a power curve on a small brake at the Five Dock factory, but the task was then transferred to the Engineering School of the Sydney Technical College, where a run was made on 2 July 1930, under the supervision of CAB Inspector Tom Johnson, and it was then taken to Randwick for tear-down inspection and further testing. At that time £1,100 had been spent on development.
Passed as satisfactory, engine Type Certificate NO1 was issued on about 7 or 8 October 1930, and it was subsequently fitted to VH–UOG, with the radiator mounted under the rear of the engine bay, for the required 50 hours of flying time, after which it was removed and fitted to ‘Wonga’.
The delay in gaining a Type Certificate brought about outspoken criticism of CAB from the two groups of investors who had backed the project in turn, to make a commercial proposition of the Hornet. After the first could get no satisfaction from CAB and was disbanded, a second was formed, and one of its members planned to install a Hornet in his own aircraft for the 1929 East-West Air Race. Unfortunately one of the Race conditions stipulated full airworthiness certification for each entry, and this one was therefore ineligible. It also ruled out a Hornet-engined entry for the P. Viner Cup which had been presented to the Aero Club for competition.
It was intended that Hornets be built for the Centenary Racer with a dry-sump installation, for an aircraft which Edgar Percival had in mind (apparently the basic layout which was later detailed for him in England, and developed into the Percival Gull), for another home-built aircraft, now untraceable, and another for General Aircraft Co. An unsuccessful attempt was made to certify it in time to interest the RAAF, which had earlier called tenders for engines suitable for Moths and Avians, and had paid a visit to the Harkness & Hillier factory to inspect the Hornet. One was sold for fitment to a speed boat, and was apparently in use for many years, but the ones for the Racer could not be completed in time for installation, and ADC Cirrus Hermes were specified instead.
For those produced beyond the prototype, a Lidcombe firm, acting as agents for Vickers, did all the forgings. The actual number built is not known, as no firm figure can be found from any source, but it would seem that possibly five or six were completed, several of which were used in speed boats and speed cars — in September 1966, Don Harkness advised that he had just bought one of his engines back, but did not say from whom.
The Hornet was the first really suitable aircraft engine designed and built in Australia, and it was expected that it would be possible to sell them at a lower price than the comparable Gipsy-I and Cirrus engines, with which it was interchangeable in the relevant aircraft. However, lack of support put an end to the project.
Moths at the Cockatoo Dockyard
With the experience which he had had at the famous Cockatoo Dockyard including methods, and costing, Wing Cdr Wackett (he resigned from the RAAF, but remained on the Reserve as a Wing Commander, after closing down the establishment at Randwick) formed the opinion that the organisation’s aircraft engineering section would be able to build a wooden DH60 Moth for between £350 and £400. After this was discussed by Air Board it was noted on 12 September 1932 that such a result would have a direct bearing on whether any future Moths would be built in wood or metal, and that the Dockyard’s Aircraft Division was almost without work.
Accordingly the order was recommended, and on 28 October the resultant approval was passed to the Dockyard, detailing one DH60G airframe, to be completed and delivered to Mascot by 15 June 1933. Certain of the components were to be issued by the RAAF for incorporation, and all the drawings and specifications, held by the Defence Department, were to be forwarded to the company within the following week.
Also provided was RAAF MOTH (WOOD) TECHNICAL ORDERS, RAAF AIRCRAFT GENERAL INSTRUCTIONS, and RAAF WORKSHOP INSTRUCTIONS, which Wackett presumably had himself, or might have written some of them. Flt Sgt J.R. Lockington was attached to the Dockyard to inspect work for DTS and SAP, as it progressed. (SAP is believed to be an abbreviation for a proposed post of Superintendent of Aircraft Production within CAB, to oversee the further production of DH60’s for civil use, as proposed by Wackett. In the event, such did not eventuate, and the post did not come into being.)
Work commenced immediately, and on 25 November it was reported that all timber had been tested and passed by inspection, manufacture of ribs had commenced, all the main components had been rough sawn, and the fuselage jig had been set out and checked.
The subsequent reports to the Defence Department are summarised as follows, and show the rate of progress attained:-
30 December 1932 All mainplane ribs manufactured, fin completed, tailplane ready for assembly, and all ribs and spars completed for elevators, rudder, and ailerons. The fuselage was held up for lack of metal fittings, although a quantity of these were then being processed.
13 January 1933 Cowls being made, fuselage formers being steamed and bent, ply bulkheads being fitted. Spindling of wing spars completed and the necessary drilling underway, and all fuselage fittings completed. 10 February 1933 Control surfaces covered, fuselage internal components being fitted, mainplanes awaiting assembly, undercarriage compression members and airscrew being manufactured.
The RAAF was responsible for issue to the Dockyard, for fitment to the aircraft, of the engine, instruments, streamline wires and fittings, wheels, fuel lines and cocks, control system, exhaust group, windscreens, tail skid, axle assembly, fuel tank, centre-section struts, and front mainplane-attachment fittings. However, there was some delay in delivery of a number of these parts and, in the case of the metal fittings, the Dockyard was originally under the impression that they would be supplied. When it was found that many of them would not be, they were manufactured on the basis of one set off, for that aircraft only.
On 10 March it was reported that the aircraft was at an advanced stage, and expected first flight was then 3 April, as A7–55 — it was handed over to the RAAF, at Mascot, on 4 April, having been flown initially by (it is thought) Flg Off Charles Douglas Candy (eventually AVM Candy).
He then ferried it to 1AD Laverton with Wg Cdr Eric C. Harrison, the Director of Aircraft Inspection, accompanying him. After a technical inspection and condition report carried out by 1AD, a progressive inspection schedule was laid down for its further RAAF use.
Notwithstanding the original price estimate, the actual construction cost came to £1,016/4/- , which figure included overhead and profit margin, but not the sum of £76/8/- spent on jigs and tooling, nor the value of the parts and materials issued by the RAAF, namely £672/10/4. The overall cost of the aircraft was therefore £1,765/2/4, and in a letter to the Secretary, Department of Defence, on 22 June, in answer to a request for a reduction in price, the Dockyard stated that the original quote was based on large quantities of aircraft being manufactured, and on the fact that certain parts would be issued ex-RAAF stock.
The necessary manufacture of scores of individual metal fittings for this aircraft had made tooling and manufacturing costs unnecessarily high but, in deference to the request, it was stated that all profit and overhead charges, totalling £347/13/-, would be waived. The Dockyard therefore gained nothing but the experience.
Allotted to NO1 Squadron at Point Cook on 24 January 1934, it was used by the flying training course then in progress, and a 50-hourly inspection on 15 February brought the comment that it compared favourably with standard Gipsy Moths. At July 1935 it was operating on floats for seaplane training, at Point Cook also.
Some measure of fame was achieved by it when the Australian Government hurriedly equipped RRS (Royal Research Ship) ‘‘Discovery II’’ with a Wapiti and A7––55, and sent the ship to the Antarctic from Melbourne on 23 December 1935, to search for explorer Lincoln Ellsworth, who had disappeared with his Northrop Delta on 23 November while on a trans-Antarctic flight.
Flown by Flt Lt Gilbert Eric Douglas, A7––55 took off from the Bay of Whales on 16 January 1936, and located Ellsworth and his companion at the Little America base, to which they had trekked after running out of fuel 25 miles south — the base was in fact only about five miles from the ship’s position.