ML Aviation Utility
| ML Aviation Utility | |
|---|---|
| Type: | experimental microlight |
| Design country: | |
| Manufacturer: |
ML Aviation |
| First flight: |
March 1953 |
| Number of pieces: |
4th |
The ML Aviation Utility was an experimental light aircraft concept that was also subjected to practical testing. The manufacturer was the British company ML Aviation in the early 1950s . The plan was to create an aircraft that could be easily folded when folded and made ready for the pilot quickly by inflating the wing and hanging a wooden, foldable “gondola box”.
history
One can view the concept of an inflatable utility aircraft as an attempt to produce a simple, light and inexpensive aircraft for military purposes, especially for army requirements. The device was intended to be used for reconnaissance and liaison tasks by army officers in the company command rank.
The machine was designed by Marcel JO Lobelle, who previously worked as chief designer for Fairey and B. for which Swordfish was responsible. Much of the design and research, however, was done at the Research and Development Establishment, RAF Cardington (Bedfordshire). This is also where the first prototype was completed along with two sets of delta-shaped wings. The prototype called "Cardington Kite" first flew in March 1953 at RAE Twinwoods airfield.
The first public demonstration took place in August 1955. At the same time, the Ministry of Supply (MoS) announced that it had placed an order for three development machines with ML Aviation. It was not until August of the following year that the first photos of the clearly further developed version, now known as the ML Utility Mk.1 (RAF serial number XK776), appeared in the press. The wing, which is now made of a different material, was given a “double tail unit” instead of the single central fin. The "nacelle" in particular was heavily redesigned and was now slimmer and longer than before, with a throttled 60 hp Walter Mikron III engine being used.
By August 1957, the Mk.1 had completed 40 hours of flight and had reached a maximum height of 210 m. A total of three Mk.1 gondolas were produced (XK776, XK781, XK784), plus twelve sets of wings, each with its own name. These were interchangeable between the gondolas, but had different elevon areas, profile depths and total areas. No further production orders were placed. The estimated price of the Mk.1 for civilian users would have been between £ 400 and £ 900, the then price for a family car.
construction
The two sets of wings (referred to as Loopy and Loopy2 ) for the first prototype consisted largely of fabric, which was also typically used for inflatable boats. The material of the Mk.1, however, was a rubberized cotton fabric. The wing got its profile shape (approximating to NACA 0024) through internal transverse intermediate webs, which were automatically pulled tight when inflated. These act as membranes that are well air-permeable when inflated, but should only release the air with a delay in the event of damage. This would leave enough time to land safely in an emergency. At the trailing edge of the profile, two additional inflatable surfaces served as elevons , and an additional central vertical surface increased flight stability.
A wooden box-shaped gondola was arranged under the wings, which in turn sat on a solid and very simple tricycle undercarriage. The drive of the prototype consisted of a 65 HP McCulloch engine and allowed a top speed of 72 km / h and a stall speed of 29 km / h.
The pressureless wing could be rolled up in a sack on a jeep and the gondola pulled as a trailer. To set up, the wing was first pressurized to around 1 psi using a mechanical or hand pump. A small wind-powered pump and a relief valve were provided to maintain the pressure during the flight .
It was controlled by a rod that hung down and was connected to the elevons by cables. Fuel was carried in two cylindrical containers that were tied under the wing with straps. During a demonstration in May 1957 it was shown that commissioning could be carried out within a short time with the help of two people. So it took 15 minutes to inflate, then the fuel tanks were attached and the engine started.
Whereabouts
The XK776, one of the foldable chassis and a wing were handed over to the Royal Aircraft Establishment Station Cardington.
Comparable aircraft types
- In the second half of the 1950s, Goodyear implemented a similar concept of an inflatable airplane with the Inflatoplane . However, there was no series production in this case either.
- The Ryan Flex Wing , whose wings were designed according to the Rogallo principle , pursued the concept of an ultralight aircraft that could be used for military purposes and that was easy to transport and operate.
Technical specifications
| Parameter | Data (Mk.1) |
|---|---|
| crew | 1 |
| Passengers | 0 |
| length | 7.05 m |
| span | 10.68 m |
| Center wing depth | 5.34 m |
| Wing area | 36.2 to 49.2 m² (depending on the leaf set) |
| Empty mass | 234 kg |
| Max. Takeoff mass | 450 kg |
| Cruising speed (35 hp) | 80 km / h |
| Top speed (38.5 hp) | 93 km / h |
| Climb performance | 214 m / min |
| Maximum flight time | 2.5 h |
| Engines | 1 × Walter Mikron III four-cylinder in-line engine |
literature
- The Flying Mattress , in Airplane Monthly, November 1974, pp. 954-957
- John Fricker: Inflated Ideas , in Airplane Monthly, December 2004, pp. 80-84
