Is the LS10 a Winner's Glider?

First place at Hockenheim, first place at Bayreuth - a good start in the 2004 contest season for the LS10-a

 a report by Gerhard Marzinzik in the August, 2004, Aerokurier

Did the Rolladen-Schneider factory produce a new, contest-winning glider with the LS10-a shortly before it went bankrupt last year? The best is yet to be seen of this new glider which was developed as the successor to the LS6 18 meter flapped ship and is now being built by DG Flugzeugbau. It will be flown at the end of July and beginning of August at the European Championship contest at Pociunai, Lithuania. The pilot will again be Makoto Ichikawa who proved himself to be superior during the eight day evaluation at the Hockenheim Soaring Week.

 

Holger Back could not have wished for a better start to promoting the LS10 for DG Flugzeugbau, than by winning the Qualifying Contest at Bayreuth. He sees the best chances for the LS10 in the hands of dedicated contest pilots, who are discovering the 18 meter class in greater numbers. The LS10 would seem to be a straggler among the 18 meter gliders, but it has the luck that there is a greater interest in this class now. Whereas the 15 meter class seems to have almost dried up if one looks at the number of entries in the Qualifying Contest this year.

At Rolladen-Schneider, the LS10 was conceived as a combination glider for the 15 and 18 meter classes. The four-part wing divides close to the fuselage for this reason. This was done so that the wing planform could be optimized for both configurations. A 15 meter version is not being considered at DG Flugzeugbau because of the erosion of interest in this class. The current wing division will remain as an advantage for low weight of the four wing parts because a two-piece wing of the same form is not feasible to build.

The designer, Werner Scholz of the Steinbeiss Institute in Stuttgart, planned a glider with the same easy handling characteristics typical or the LS series. In contrast to the LS6, better slow speed and high speed performance was designed into the LS10. The optimization of the performance was not to be at the expense of the low sensitivity of the LS6 to turbulence, rain and bugs. This goal would seem to have been reached as demonstrated by the initial contest experience and results. Holger Back said, "At Bayreuth I had no disadvantage during rain showers."

From the LS1-f to the LS10-a in the performance-optimized fuselage

Turbulator tape has been added - new for LS gliders - on the underside of the wings to prevent the onset of laminar bubble release. The same as with the LS6, the LS10 is equipped with full span flaperons. Landing approach can be controlled with the large, double layered spoilers on top of the wings. A modified LS6 fuselage similar to the LS8 construction has been added to the new wings. The control stick is derived from the LS8-b but with the aileron linkage made smaller and installed lower in the fuselage. The basic LS6 fuselage was used to save design time. A mock-up for a new fuselage is ready. The decision has not yet been made as to when the new design will be used. Holger Back said, "There have been few people who seem interested at this time."

With regard to passive safety, designer Werner Scholz is sure that the LS fuselages and cockpits already meet a very high standard. During the further development of the LS6 to the c model, LS designer Wolf Lemke carried out 45 degree impact crash tests in the factory. According to Werner Schultz, a safety cockpit has come from this which had anticipated the recommendations of the TÜV Rheinland resulting from TÜV's crash tests.

A turbo version is planned for the future. The motor system will be copied from the LS8s-t that is currently being modified to an electrical spindle drive at DG-Flugzeugbau in Bruchsal. The planned hydraulic system for raising the motor (20 HP - Solo - 2 cycle) turned out to be too costly for DG to produce.
Until now there is only one LS10-a prototype which may well fly in a year. It celebrated its official debut at the AERO 2003 Exposition.

The trial flights were pushed way back because of the troubles caused by the bankruptcy proceedings. Now that those troubles have been cleared up, DG-Flugzeugbau has decided to begin production in 2006. And now Aerokurier has taken the opportunity to write up their first flight impressions of this new glider. Since this is a first prototype, it is too soon to take their impressions too seriously. One should wait until No.2 and No.3 gliders are completed and test flown next fall and the following spring before any reliable data can be published.

LS6 pilots will immediately be at home in the LS10 since the cockpit is the same. Even the connecting link for the flap handle is original from the LS6. As shown by contest results, the flap detent system seems to be about right. An increase in performance is expected from the careful fitting to the LS10 profile. The same is to be expected of the optimization of the position of the turbulator strips on the underside of the wings that, up to now, have been determined by calculation and always on the conservative side. This will be further adjusted according to the oil streak pictures from the European Championships.

The red, VNE mark on the airspeed indicator is smack on the 200 km/h mark. (The flutter tests have not yet been done.) We expect the final VNE to be 280 km/h. The target maximum weight of 600 kg (wingloading 53 kg/m2) still awaits factory tests.

 

In one respect, the LS10 differs from its predecessors in a very positive way. It shows up at the beginning of the roll on aerotow. The large main wheel increases the rolling angle of attack causing the LS10 to get off the ground much sooner. I can actually start the roll with positive flaps behind the acrobatic tow plane SP-91 belonging to Alwin Güntert. Aileron control is immediately available giving an LS-feel right from the start of the roll. The LS10 flies as if it could read the mind of the pilot. It flies straight and level without wavering and, at the same time, rolls easily into circling flight. Even in the unstable cores of the strong blue thermals of the Rhein Valley, it centers them with agility and lets the pilot know which part of the thermal is stronger.

In this respect, this 18 meter glider shows the traditional characteristics of Rolladen-Schneider gliders.

It is a glider which is exactly to the taste of LS fans.

There are no surprises in the slow flight regime. In spite of setting the C.G. at the rear-most point, the LS10 does not tend toward abrupt maneuvers (at a wing-loading of 34 kg/m2). Buffeting followed by turbulence on the canopy when the horizon drops leaves no question that a stall is approaching when I pull the stick all the way back. The airspeed needle swings to the lowest readings during this maneuver.

The control forces fell off somewhat. It is not so understandable that they are greater than in the LS6/18. Holger Back lays the blame on it being a special prototype deficiency. He suspects it is caused by a high amount of friction in an uncleanly sliding, automatic control hookup in the fuselage. This will be corrected in the pre-serial production prototypes. There seems to be some decrease in the aileron authority as shown in 45 to 45 degree roll time tests. This is hardly noticeable in ordinary flight. However, in straight and level flight, the LS10 is easy to trim and has a quiet cockpit even at 200 km/hr.

New turbulence profiles will be developed for the wing-fuselage transition.	A lot of trouble is being take in production to smooth out sharp transitions to guard against spanwise splitting.	The fin tank and rear wheel are standard. The tank is filled from underneath.

Overall, the LS10 is a glider that earns one's trust very quickly. Pilots will not need to be thinking about where "gremlins" may be hiding in unusual flight situations.

Whether "Mac" Ichikawa will be in the top group with the LS10 in the European Championships, remains to be seen.

Gerhard Marzinzik