International Model Aircraft Limited and Naval Towed Glider Target Development
The company set up offices
and a workshop in Rocks Lane, Thame, to design, test and develop, towed
glider targets for the Royal Navy. The first references to testing
experimental models at Haddenham appear in 1942 with a visit by a Lt.
Stanley Bell RNVR on the 17 August, quickly followed 2 days
later by a report that testing was underway. Lt. Bell was the resident
naval representative at IMA, Thame, and for all practical purposes appears
to have controlled all activities related to the whole development
programme.
The early work at Haddenham was with model gliders with
a wing span of 8ft and were towed across the airfield behind a motor car.
Later a Boulton-Paul Defiant MkII was brought into the test programme for
trials, possibly Fleet Air Arm Defiant TTI DS139 (converted from a MkII),
but it was not considered to be a particularly good tug because of its
poor performance in the climb following take-off – it wasn’t steep enough.
Trials had also continued at Haddenham with a Miles Master II on loan from
No.1 Glider Training School and the services of a very experienced tow
pilot, Flt.Lt. G. Wells, flying in his own time. Flt.Lt. Wells was later
loaned (not attached or seconded) to IMA for a period of some four months
to carry-out the towing trials.
In February 1943 Lt. Bell set out
proposals for the design, development and testing of a number of different
models, some of which were part of the overall plan and others which may
not have been. The proposals included tests on two types of model, both
with a wing-span of 16ft. They were to be towed behind cars at speeds of
up to 110 mph. The location for these tests is not given, but clearly the
airfield at Haddenham would not have been suitable for tests at the
top-end of the speed range, or anywhere near it. There were obviously cars
that could achieve such speeds, but not on grass within the confines of
such a small airfield. These were to be followed by aircraft tows in a
whole variety of different configurations. Concurrently, similar trials
were to be carried-out with a 12ft wing-span tail-less prototype of Bell’s
own design and a 16ft model of a Heinkel He111K twin-engined
bomber.
In support of these proposals there was a requirement for
more space on the airfield and a number of specialists to be added to the
IMA workforce at Thame. Eventually the space issue was resolved when the
ATA (who were now resident on the airfield) agreed to the use of a
blister-hanger, to be used as an erection-shop and cover for the towing
aircraft, and a Nissen Hut as an office. It was also envisaged that RAE
Farnborough would be required to carry-out wind-tunnel tests on each
model. Further aircraft were also requested for tow testing; a Westland
Lysander and a Hawker Henley, but in the interim Lt. Bell suggested that a
Master II, fitted with a suitable winch, could be used. This aircraft
would be used for towing at speeds in excess of 200mph, pending the
arrival of a Miles M33 Monitor target tug – presumably the Fleet Air Arm
TT MkII. In support of this he goes on to suggest that the Monitor would
be able to tow a 20ft (sic) glider target on 6,000ft (of cable) at
well over 300mph.
On the 3 March a Miles Martinet TT1 (HP216) was
delivered to Haddenham, followed on the 19 March by another (HP428),
delivered by the ATA direct from Philips & Powis at Woodley (Reading).
There appears to have been some confusion between Lt. Bell, some
intermediaries, and 41 (Maintenance) Group HQ, Andover – the Group
responsible for supplying and allocating aircraft. Bell had originally
asked for a Martinet with an electrically powered winch but the first to
arrive was fitted with a wind-driven unit. This was at first deemed
acceptable for initial trials but a request was made to exchange it within
a week or so with the type originally requested. In the intervening period
the Martinet fitted with the ‘wrong’ winch was found to have adequate
performance, but despite a telephone call from Bell to 41 Group the second
one was still delivered, complete with an electrically powered winch as
per the original request. There followed what seems to be considerable
debate to get it removed; Bell didn’t want it and the ATA didn’t want it
sitting on their airfield!
In a memo dated 2 August 1943 a report
on trials at HMS Excellent – a shore establishment at Whale Island,
Portsmouth – raised a number of important points. The first was that the
performance of the 16ft span glider was better than standard sleeve
(banner) targets, but the 32ft glider was to be preferred. Second was the
radar response which proved to be better on the production prototype which
had more sheet metal in its construction than earlier models. The final
point raised the question of gunners firing at the tug rather than the
glider since it was difficult to tell the difference when towing a 32ft
span glider. The outcome was that 32ft span gliders should take priority
over the 16ft glider.
Already in train at about the same times was
a full demonstration of 16ft span gliders at Haddenham during the early
evening of 5 August. Later in the month recommendations were made
regarding the identification and colour of the gliders. There is no
specific mention of the 32ft glider, but in the case of the 16ft model,
there was a comment indicating that although it was not too important they
should preferably be red or yellow in colour. It was also recommended that
ROYAL NAVY should be printed on the fin and that roundels should also be
applied as part of the overall scheme.
On the 10 February 1944 both
16ft and 32ft span models were delivered by road to RAF Chalgrove for
towing trials which could not be carried out Haddenham since there were no
hard runways. The following morning a Defiant and a Martinet arrived, as
did a Royal Navy Vultee Vengeance TTIV. Just what the programme was, or
its purpose, is obscure, since the only reference to a tug aircraft and
glider taking-off relates to the Martinet. It seems a little unlikely that
at least one of the other aircraft would not have participated in some
way, if not both. Three months later on the 12 May 1944 trial of two 32ft
all-metal wing targets were planned to take place at RAF Oakley. By the
end of August 1944 practically all the development work was
complete.
Below is a page taken from a book about Lines bros. and
shows the target production line at Merton.
