ASH 31 Mi

  Our new motorglider with 21m and 18m span
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  ...enjoy the Open Class Feeling

Total independence in the 18m Class.

Enjoy an Open Class Feeling with 21m tips,
and have endless fun in the sky...

With our self-launching motor glider ASH 26 E we introduced many innovations which have since been enthusiastically embraced by more than 250 customers from all corners of the globe.

Over recent years our customers have put forward many welcome suggestions. We have implemented them and today we are pleased to introduce the result – a new self-launcher for 18m Class which can also be flown in Open Class after fitting the optional 21 metres outer wing panels. Regardless of the class you choose, the fun and enjoyment of flying this glider was our guiding design principle.

Schleicher fans are certainly not surprised that this new model was named ASH 31 Mi. It should also not come as a surprise that 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 7.00m half span point) not only allows the use of a small standard trailer but 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.

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) we expect an almost 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. This allow steep descents and – 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.


An unprecedented laminar airflow over 95% of the lower wing cord makes for excellent all-round performance. Contributing are blow turblators in the flaps and ailerons as well as Mylar type gap seals on top and bottom. 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 13.2m the ASH 31 Mi features an aspect ratio of more than 33 and a maximum wing loading of 53 kg/m².

The maximum water ballast quantity of 140 litres can be adjusted in favor of one or two fuel bladders with a total capacity of 30 liters. 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. Less time for ballasting and preparation means more time for flying.

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, at any time the pilot can quickly revert back to a standard tailwheel.

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 center 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 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.

It goes without saying that we have also retained our award-winning safety cockpit although 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, a very quiet cockpit, excellent visibility, an adjustable headrest and a powerful cockpit ventilation system 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. For the fastidious pilot we have different cockpit interior designs and materials on offer.

Powerful fuel-injected engine

Now a word or two on the drive unit. We have decided in favour of the more powerful fuel-injected version of our well-proven and liquidcooled rotary engine. It is already in service with well over 400 self-launching Schleicher gliders and is equipped with a dual ignition system.

Its modern fuel injection system features automatic altitude compensation to ensure that the generous power output of 41 kW (56 hp) and the 4 m/s (8 kt) climb rate are hardly compromised at altitude. Rotary engines offer simplicity and reliability in a compact design while having a very high power output for their weight and size. There is also no requirement for special fuel such as AVGAS or two-stroke mixture.

Thanks to the electronic fuel-injection system, the fuel consumption is significantly lower compared to conventional two-stroke engines. Our standard 16 litre fuselage tank allows almost a full hour of engine running but for even greater endurance, the owner can install additional wing tanks holding up to 30 litres.

A very simple engine management system is another hallmark of this power plant. A mechanical propeller stop eliminates the need for a host of sensitive electronics, sensors and switches and this contributes to overall reliability. Even during operation the engine remains firmly bolted to the noise-shielding fuselage where it is permanently connected to a large and effective silencer. This is not only a big plus for the environment but is just as important for pilot comfort. Only the propeller pops out of the fuselage and the drive belt is only under tension while the engine is in use.

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 70 to 75 kt (approx. 140 km/h) and represents another most welcome advantage over conventional two-stroke technology.

But that is not all this engine has to offer. For maintenance purposes 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.

In summary, the new self-launching ASH 31 Mi represents a "world’s first" as it meets the requirements of the FAI 18m Class on one hand and Open Class on the other. The optional outer wing panels with 21 metres span further enhance performance without sacrifising its superb handling and the modern rotary engine comes as a bonus. It is without doubt the most sophisticated drive unit available for self-launching gliders today and provides the owner with a long list of advantages over conventional power plants.

Design and construction subject to change without prior notice.

We would be glad to send you more information and an offer without obligation.

Alexander Schleicher GmbH & Co.