ASH 31 Mi

Our successful motor glider with span variants of 21m and 18m

ASH 31 Mi
  • Total independence in 18 m class.
  • Enjoy an Open Class feeling with 21 m tips.
  • Have endless fun in the sky.

Within the last 20 years a lot of innovations have been made with our self-launching motor glider ASH 26 E. More than 250 customers from all over the world have been enthusiastic about it.

With the ASH 31 Mi we are continuing this successful story. In 2013, only four years after the start of series production, serial number 100 could be delivered.

For many years our customers have put forward suggestions and requests. Designer Martin Heide and his team have implemented them. The result is a compact 21m span self-launching motorglider, with an “Open-Class-Feeling”. The powerful engine system enables to go airborne anywhere you want. After fitting the shorter outer wing panels the ASH 31 Mi can also be flown competitive in the 18m class. Regardless of the class you choose, the fun and enjoyment of flying this glider was our guiding design principle.

The numerous aerodynamic advances, which have already made the ASG 29 a top performer and best seller in FAI 18m Class, have been fully integrated.

The totally new four-piece wing (with a joint at the 7.00 m half span point) can be transported in a small standard trailer. It also offers an almost-perfect wing geometry for both 18m and 21m span. As with the ASW 28-18 and the ASG 29, the removable winglets of the ASH 31 Mi are used for both wing configurations.

Most modern wing structure

Due to the use of the proven flap and aileron control system of our ASG 29 (and the fact that the ailerons have been extended almost to the tip of the wing) there will be an identical rate of roll for the ASH 31 Mi. Separate control mechanisms for flap and aileron are installed in order to combine pleasant thermalling behaviour with very docile stall characteristics.

Of course, we have also retained our famous control mixer system which provides negative aileron deflections on selection of landing flaps. Even in extreme crosswind situations – it enables pilots to maintain aileron control during ground roll until the aircraft has almost come to a complete stop. It is unique to Schleicher gliders, makes landing easy and has greatly contributed to our outstanding safety record.

The high-performance wing profile with a blowhole boundary layer system, integrated in flaps and ailerons, intentionally trips the laminar airflow as far back as 95% of chord. Needless to say that top and bottom of all control surface gaps are sealed by “Mylar” tapes.

Our newly-developed wing structure allows for a wing span of 21m despite of a wing section as thin as 13%. With a wing area of 13.2 qm the ASH 31 Mi features an aspect ratio of more than 33 and a maximum wing loading of 53 kg/qm.

The maximum water ballast quantity of 140 litres can be adjusted in favour of one or two wing fuel tanks with a total capacity of 30 litres. Maintenance-friendly water bags have been fitted, mainly for this reason. They also allow a very close placement to the C of G and hence make a trim tank in the fin obsolete. Special attention was given to fuselage-wing-transition and empennage as the latest aerodynamic research pointed to these areas for further performance enhancement.

For the competition pilot we will fit a low-drag tailwheel but “just for fun pilots” can install a steerable tailwheel for easier taxiing under power. Of course, the pilot can quickly revert back to a standard tailwheel any time.

Special highlights are also the bug wipers, integrated in the fuselage contour and the anti-collision-light (ACL) in the nose of the vertical stabilizer.

We have also retained the large diameter well sprung 5.00-5 main wheel from the ASH 26 series. This proven and robust undercarriage not only comes with a state-of-the-art hydraulic disc brake but it also allows take-offs and landings on soft airstrips. A clever design places the big 5.00-5 main wheel well forward of the aircraft’s centre of gravity. The advantages are plentiful; first of all it means that ASH 31 Mi pilots don’t need to be concerned about scraping the nose on the ground on application of take-off power. Secondly, in conjunction with effective rubber shock absorbers, it adds greatly to pilot’s comfort on rough airfields. Thirdly, it ensures the highest possible degree of safety due to the most generous ground clearance of any glider in this class.

Safety in the superior comfort cockpit

It goes without saying that we have also retained our award-winning safety cockpit. In addition it has been upgraded by integrating the latest research findings and test results. Pilot protection remains our priority while at the same time ensuring the best possible ergonomics, excellent visibility and a roomy cockpit. Our philosophy could not be clearer when it comes to pilot comfort. We firmly believe that a larger “feel well cockpit” adds much more to the success of a flight than a cramped and performance optimised “minicockpit”. For this approach we are getting increasingly strong support – not only from taller and/or larger competition pilots.

Sufficient room to move, an in-flight adjustable backrest, an adjustable headrest, a powerful cockpit ventilation system and an excellent visibility is what Schleicher customers have rightly come to expect. Even entering and exiting the aircraft is easy and comfortable as the instrument panel lifts up with the canopy. Pilots can choose between different cockpit interior designs and materials.

Powerful, proven and low fuel consumption

The well-proven, liquid and air cooled rotary engine produced by Austro Engine, is also installed in the ASH 31 Mi. It’s equipped with a dual ignition system and a fuel injection system for optimum ease of operation. This compact engine system with the special designed Schleicher propeller has proved its reliability in more than 500 self-launching Schleicher gliders.

Thanks to the electronic fuel-injection system, the fuel consumption is significantly lower compared to conventional two-stroke engines. Our 16 litre fuselage tank allows approx. one hour of engine running. Its modern fuel injection system features automatic altitude compensation to ensure that the generous power output of 41 kW (56 hp) is hardly compromised at altitude.

Another major advantage of the engine is the vibration-free running at all power settings. This allows extended power cruising for ferry flights and avoids the usual “Saw tooth” climb/cruise method. Even flying through controlled airspace at an assigned altitude presents no problem to this aircraft or its engine. It is best conducted at approx. 140 km/h (70 to 75 kt) and represents another most welcome advantage over conventional two-stroke technology.

Compact and maintenance friendly

A folding drive belt allows the engine to remain stationary in the fuselage where it is permanently connected to a large volume muffler. Only the propeller made by Schleicher, extends from the fuselage and can fully be retracted. It keeps the air resistance as low as possible.

Concerning maintenance, this engine also offers great advantages.

The entire power plant can be easily removed. It has no service life limitations and doesn’t require an overhaul after reaching a certain number of running hours or years of service.

The ASH 31 Mi fulfils your dreams

It was certainly a brave to create a new class with the ASH 31 Mi. But the success of this motorglider shows, that we hit the nail on the head. Excellent performance, high quality building construction, maximum comfort, paired with state-of-the-art safety technology, a wide range of applications and a powerful engine system characterize this single seater and offer the pilot the opportunity, to make his flying dreams come true.

Photos: Manfred Münch

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