Monthly Archives: May 2017

The NA-16 (actually the NA-16-1A)

CAC Wirraway

During the process of selecting a design to be constructed as the Wirraway, the Air Board requested CAC to purchase one example of their chosen design so that it could be tested by the RAAF. Thus CAC ordered the sole NA-16-1A in early 1937. The NA-16-1A (also known by its NAA accounting code or “charge code” of NA-32) was a single-engined 2-seat training and general purpose aircraft.

In the newspapers of the day, this aircraft became widely known as the “NA-16”, even though this was not technically correct. In this short article, I will refer to the aircraft by its NAA model number, NA-16-1A.

The NA-16-1A was constructed at the Inglewood, California factory of NAA and flight tested before being dismantled and crated prior to shipping to Australia. Contemporary manuals published by NAA describe the NA-16-1A as “Modified BT-9D, Australia”. The main modification was the installation of a Pratt & Whitney Aircraft R-1340 Wasp engine, as opposed to the Wright R-975 Whirlwind in the BT-9D.

Above: This photograph shows the sole NA-16-1A in California prior to its delivery to Australia (San Diego Air and Space Museum).
Above: A head-on photograph of the NA-16-1A in California prior to its delivery (San Diego Air and Space Museum).
Above: Another photograph of the NA-16-1A in California prior to its delivery.
Notice that the aerial mast appears to have been removed when this photo was taken (San Diego Air and Space Museum).
Above: Another photograph of the NA-16-1A in California prior to its delivery. The corrugated skin on the horizontal stabilizer (as well as the tail fin) is evident in this image (San Diego Air and Space Museum).

The NA-16-1A arrived in Australia on August 9th 1937[1] and was assembled at Point Cook, since the CAC factory was still under construction.

There was a good deal of discussion about who should carry out the first flight of the aircraft in Australia once it had been assembled, since CAC had not yet engaged their own test pilot at this point. Options canvassed included:

  • Major Victor Bertrandias of Douglas Aircraft (who was due in Melbourne in October, but was obviously going to be too late)
  • Moye Stephens, the pioneering aviator and co-founder of Northrop, who was in Australia at the time on behalf of Lockheed
  • Eric Chaseling (who was in California at the time, taking delivery of VH-ABH from Lockheed for Associated Airlines, and could be checked out by NAA before leaving for Australia, where he was due on 16 September)
  • Sqn Ldr Frederick Scherger, Director of Training for the RAAF who was a highly experienced pilot with experience on similar types

Wackett was in California at the time, but a conference between the Air Board and CAC was held in Melbourne on 23 July to discuss the question. Chief of Air Staff Richard Williams believed that RAAF pilots could handle it, but he would welcome an American expert if CAC were covering the cost. Wackett cabled on 9 August, noting Moye Stephens was in Australia, but not recommended by Kindelberger of NAA, and that he (Wackett) suggested Chaseling instead.

Several days later it was agreed that the RAAF would provide the pilot, and so on 26 August CAC was advised that Sqn Ldr Frederick Scherger would be made available.

The aircraft made its first flight on September 3rd[2] in the hands of Sqn Ldr Scherger, lasting for 55 minutes, with two loops included. The acceptance testing and handling trials program required by the RAAF was completed in six days, with a total of 6 hours 40 minutes of flying time.

Above: This photograph shows the NA-16-1A at Point Cook shortly after its arrival in Australia in 1937. It is seen in the company of de Havilland Moth primary trainers. It bears RAAF roundels, but no serial number so presumably this photograph was taken before the NA-16-1A was handed over to the RAAF on February 2nd 1938 (Australian War Memorial ref P02515.002).
Above: Cadet Geoff Nicholl (later Wing Commander) from the RAAF College, standing beside the NA-16-1A at Point Cook in 1937 (Australian War Memorial ref P02515.001).

In December 1937 a series of comparative flight tests were carried out between the NA-16-1A and the NA-16-2K (a retractable-gear version).

On 13 January 1938 Ellis Wackett wrote to Williams (CAS) to reply to his enquiry about critical comments on the NA-16 which appeared in C.G. Grey’s editorial in The Aeroplane on December 8th 1937. Without naming his sources, Grey commented:

The first NA 16 to be seen in Australia was inspected at Sydney a few weeks ago… The first is still expected to fly in February. The machine did not excite much comment, and pilots who have handled it are not impressed by its performance in bad weather, when it is apt to do many things which it should not. 

Ellis Wackett mentioned to Williams that he had discussed the issue with Sqn/Ldr Scherger and F/Lt Kyle (who had flown the aircraft to Sydney and back) and they “had nothing adverse to say about it and liked flying it”.

On January 14th 1938 the Air Board wrote to the Defence Department to inform the Minister that trials of the NA-16-1A and the NA-16-2K had confirmed that the NA-16-2K had superior performance and more desirable features.[3]

Since the NA-16-1A was no longer needed by CAC for development activities, it could now be handed over to the RAAF for conversion training for the new Wirraway aircraft which would later be entering service. This took place on February 2nd 1938, and from this point its history can be traced from RAAF records. Text in italics below is taken from the service card for A20-1[4]:

02/02/1938 Received at 1 Aircraft Depot (Laverton) ex CAC. Wasp engine number 6155. Order number A.30964

07/02/1938 Issued to No. 2 Squadron, Laverton

As soon as the aircraft was delivered to the RAAF, Group Captain Wrigley, Commanding Officer of RAAF Laverton, wrote to the Air Board pointing out that there was no cock (shut-off valve) installed between the oil tank and the oil pump[5], which could result in oil draining into the head of the lowest cylinders and possibly causing damage due to the high compression in this situation. The Directorate of Technical Services at the Air Board pointed out that later Wasp engines incorporated a non-return valve which served the function of the proposed cock without adding the risk that the engine could be operated with the oil turned off at the cock[6].

During its time at No. 2 (General Purpose) Squadron at Laverton, it was noticed that a large amount of flame was emitted from the exhaust manifold when the aircraft was performing aerobatics, particularly in slow rolling vertical climbs. In some cases flames could be seen extending along the full length of the fuselage by observers on the ground when the aircraft was flown inverted.

On April 27th 1938 the CO of No. 2 Squadron wrote to the CO of RAAF Laverton to express his concerns[7] as it was observed that heat from the exhaust had blistered the dope on the cowlings and wing covering at the root of the wing and had scorched the fabric on the removable fuselage side panel. The heat had even buckled some of the wing leading-edge skin near the root. The Squadron dismantled and checked the carburetor to determine if this was the cause and it appeared that a non-return valve (intended for inverted flight) was not installed on the carburetor and this was allowing excess petrol to flow into the engine. This excess fuel was not burned during the combustion cycle and ignited in the exhaust manifold, resulting in the flames coming from the exhaust pipe.

On April 2nd the aircraft was inspected at CAC by Lawrence Wackett and Pieter Schipper (Engineering Superintendent, who had joined CAC from Pratt & Whitney Aircraft in the USA). They pronounced the damage as only cosmetic and the aircraft as airworthy. They suggested repairing the aluminium skin when the aircraft was available to do so, and extending the exhaust manifold by 12 inches to prevent the hot exhaust flowing over the wing root when the aircraft was flown inverted. Photographs of the aircraft do not show any such extension so it appears this suggestion was not followed. However photographs of the aircraft later in its life show a metal patch on the lower front of the fuselage, replacing a section of fabric covering which would have suffered scorching again.

On June 1st 1938 the Directorate of Technical Services sent 8 rollers for installation on the sliding canopy sections to RAAF Laverton[8] and on June 22nd the Commanding Officer at Laverton informed the Air Board that these had been installed on the aircraft[9].

Above: This photograph shows the aircraft at Point Cook, following it’s transfer to the RAAF as A20-1 on 2 February 1938.The fixed landing gear, direct drive two-bladed propeller and flat-panel windscreen are noticeable.
The prominent scorch-mark from the exhaust pipe (caused by the lack of a non-return valve in the carburetor allowing too much fuel into the engine during vertical climbs or inverted flight) is also obvious along the lower side of the fuselage.
Image copyright expired, courtesy of the AWM archive.

24/06/1938 Received at No. 1 Flying Training School (Point Cook) ex 2 Squadron

During its time with No. 1 Flying Training School at Point Cook, the under-side of the tail-plane was damaged[10] and the aircraft was sent back to CAC for repairs. It was also noticed that the heads were breaking off some of the counter-sunk bolts along the front of the engine cowling[11].

24/08/1938 Returned to CAC for repairs.

Part of the skin was replaced underneath the tail-plane and some local reinforcing was also added.[12]

09/09/1938 Arrived 1 FTS ex CAC

23/09/1938 Wingtip struck ground at Point Cook

On October 5th 1938 an urgent request was placed with CAC to repair the starboard aileron and wing-tip[13].

On October 24th 1938 it was proposed that the aircraft should be withdrawn to No. 1 Aircraft Depot and held there until the first squadron to be equipped with Wirraways was ready[14].

On February 2nd 1939 the spark plugs were checked by CAC and found to be in excellent condition after 20 hours running time on the engine[15].

During the middle of April it was noticed that the Exide battery was inefficient, resulting in a ban on aerobatics issued on April 20th[16].

22/08/1939 Received No. 1 Squadron ex 1FTS

28/08/1939 Allotted No. 21 Squadron ex 1Sqn

17/10/1939 120-hourly service 23/10 Engine #6155

10/01/1940 Allotted No. 8 Squadron ex 21 Sqn

17/05/1940 Allotted 1AD ex 8 Sqn for complete overhaul

24/05/1940 Received 1AD ex 8Sqn for for ARS rep

12/06/1940 Allotted Engineering School ex 1AD

23/06/1940 Issued to Engineering School ex 1AD converted to Wirraway instructional airframe #2

Above: The NA-16-1A spent the later part of it’s life as an instructional airframe at No. 1 Engineering School, Ascot Vale (the Melbourne Showgrounds). Here two W.A.A.A.F. servicewomen demonstrate hand starting techniques. Note that the aircraft was painted in the standard war-time camouflage scheme by this point of its career.
Image copyright expired, courtesy of the Argus Newspaper Collection of Photographs, State Library of Victoria.
Above: Here is A20-1 again during the hand starting demonstration “photo shoot”.
Image copyright expired, courtesy of the AWM archive.
Above: Another view of the NA-16-1A while being used as an instructional airframe. From this view it appears to have been fitted with a standard Wirraway wing centre-section with retractable undercarriage, along with a standard hydraulic system and control shelf, not fitted during its flying life. The instructor is showing the keen students how the undercarriage retraction system functions.
State Library of Victoria, ref H99 206-2172

17/10/1945 Converted to components

Bibliography

A selection of books containing information related to the NA-16-1A:

  • Hagedorn, Dan. North American NA-16 / AT-6 / SNJ. North Branch, MN: Specialty Press, 1997. ISBN 0-933424-84-1
  • Smith, Peter Charles. North American T-6 SNJ, Harvard & Wirraway – A Pictorial Record. Ramsbury, Marlborough, Wiltshire, UK: The Crowood Press, 2000. ISBN 1-86126-382-1
  • Wackett, Lawrence Aircraft Pioneer – An Autobiography.Sydney, Angus and Robertson, 1972. ISBN 0207123780

Additional internet information sources

You can find more information regarding the NA-16-1A on these websites:

Footnotes

1. “FIGHTING AEROPLANES.” The Mercury (Hobart, Tas. : 1860 – 1954) 10 Aug 1937: 8. Web. 27 Jul 2012 http://nla.gov.au/nla.news-article25419245

2. “NEW FIGHTING ‘PLANE TESTED AT LAVERTON” The Sydney Morning Herald (NSW : 1842 – 1954), Saturday 4 September 1937, page 18 http://nla.gov.au/nla.news-article17405543

3. Letter 14/01/1938 from Secretary, Air Board to Secretary, Department of Defence, RAAF ref 16/1/7. National Archives of Australia, Series number , Control Symbol 

4. Aircraft status cards, Wirraway A20-1 to A20-305. National Archives of Australia, Series number A10297, Control symbol BLOCK 107

5. Letter 7/02/1938 from RAAF Laverton to Air Board, RAAF reference 212/1/2E. National Archives of Australia, Series number A705, Control symbol 9/15/5

6. Letter 28/02/1938 from DTS, Air Member for Supply to RAAF Laverton. National Archives of Australia, Series number A705, Control symbol 9/15/5

7. Letter 27/4/1938 from CO No.2 Sqn to CO RAAF Laverton ref 212/1/2. National Archives of Australia, Series number A705, Control symbol 9/15/5

8. Letter 1/6/38 from DTS to RAAF Laverton. National Archives of Australia, Series number A705, Control symbol 9/15/5

9. Letter 22/6/38 from RAAF Laverton to Air Board. National Archives of Australia, Series number A705, Control symbol 9/15/5

10. Correspondence file 10/08/1938 reference 1FTS 2729 (FS 115). National Archives of Australia, Series number A2408, Control symbol 9/15 PART 1

11. Correspondence file 10/02/1939 reference 1FTS 2728 (FS 114). National Archives of Australia, Series number A2408, Control symbol 9/15 PART 1

12. Letter 9/8/1938 from DTS to DE. National Archives of Australia, Series number A705, Control symbol 9/15/5

13. Correspondence file 05/10/1938 reference SAB 11389. National Archives of Australia, Series number A2408, Control symbol 9/15 PART 1

14. Correspondence file 27/10/1938 reference A/CAS. National Archives of Australia, Series number A2408, Control symbol 9/15 PART 1

15. Correspondence file 02/02/1939 CAC Resident Technical Officer reference 075/39. National Archives of Australia, Series number A2408, Control symbol 9/15 PART 1

16. Correspondence file 20/04/1939 reference 250/34/17S. National Archives of Australia, Series number A2408, Control symbol 9/15 PART 1