Flight, October 1928

Berlin Aero Show 1928

The Klemm Light 'Planes

   Generally of similar design and construction, the two light 'planes exhibited by Leichtflugzeugbau Klemm of Boblingen are both low-wing monoplanes mainly of wood construction, but whereas the type L.25 is a landplane with 20-h.p. Mercedes engine, the type L.25 W is a seaplane fitted with the little nine-cylinder Salmson radial air-cooled engine. The landplane is already familiar to readers of FLIGHT, having been described and illustrated last year when it paid a visit to Croydon, and the seaplane is, therefore, perhaps the more interesting of the two. It might be mentioned in connection with the landplane, however, that the fuselage is now entirely ply-wood covered.
   As long ago as 1919 the first Klemm-Daimler light 'plane was produced by Herr Regierungsbaumeister Hans Klemm at the Daimler works at Sindelfingen. This machine flew very well with a motor-cycle engine of only 12 h.p. The fact that the seaplane type shown at Berlin, the type L.25 W, has succeeded in getting "unstuck" with three on board indicates that the efficiency of the Klemm designs is very high. The machine is not, of course, designed to carry three normally, but on the occasion in question, M. Magnet of the Salmson company provided the "overload" (which was a very substantial one, M. Magnet probably weighing some 15 stone!).
   Apart from the differences in undercarriage, and the small changes in the nose occasioned by the different engines, the two types exhibited have the same characteristics, i.e., an all-wood fuselage, ply-wood covered, and low cantilever monoplane wings, also covered with ply-wood. Folding is not such a simple operation as on British light 'planes, as each wing-half has to be detached from the fuselage and, in order to get the lower wing surface against the fuselage, the port wing has to be carried over to the starboard side and vice versa.
   A minor change is to be noted in the fuselage decking. Previously this was of the sharp-ridge "roof" type, but on both machines exhibited this has been altered to a slightly curved deck fairing more like those found on British light 'planes.
   Both machines are well made and well finished, and both have a fairly large luggage compartment aft of the rear cockpit. The landplane is exhibited with this space occupied by a well-stocked picnic basket. It is interesting to learn that more than 100 of the Klemm light 'planes have now been built, and sold partly in Germany and partly outside.
   No information is available concerning the dimensions of the two Klemm monoplanes, but following are the weights and performances of the L.25 landplane: tare weight, 265 kg. (583 lbs.); permissible load, 215 kg. (473 lbs.); total loaded weight, 480 kg. (1,056 lbs.). Maximum speed, 115 km. h. (71-5 m.p.h.); landing speed, 35-40 km./h. (22-25 m.p.h.), presumably according to whether the machine carries one or two occupants. The range is given as 700-1,500 km. (435-930 miles), the greater figure presumably representing the range when no passenger is carried and the weight thus saved used for carrying extra fuel. With full load the ceiling is given as 4,000 m. (13,150 ft.), and with pilot only as 6,000 m. (19,700 ft.). The climb to 1,000 m. (3,280 ft.) is carried out in 14 mins. with two on board, and in 9 mins. with pilot only. The petrol consumption is given as 6-7 litres (1-3 - 1-5 gallons) per hour. Assuming that the machine cruises at 60 m.p.h., this gives a mileage of approximately 40-45 m.p.g.
   The Klemm L.25 W seaplane with Salmson engine has a tare weight of 350 kg. (770 lbs.), and the permissible load is 250 kg. (550 lbs.), bringing the total loaded weight up to 600 kg. (1,320 lbs.). The maximum speed is given as 130 km./h. (81 m.p.h.), and the landing speed as 50 km./h. (31 m.p.h.). The range as single-seater and two-seater is 450-1,000 km. (260-620 miles), and the petrol consumption, 10-12 litres (2-2 - 2-64 gallons) per hour. The ceiling is 3,500 m. (11,500 ft.) with full load, and 5,000 m. (16,400 ft.) with pilot only. The machine is stated to get off the water in 18 seconds, and to climb to 1,000 m. (3,280 ft.) in 15 mins. with full load and in 8 mins. with pilot only.
   The floats of the L.25 W are of wood construction, and judging from photographs, the machine is very "clean" on the water.

Flight, June 1929

OLYMPIA AERO SHOW 1929

The Klemm-Salmson

   The L.25 monoplane of the Klemm Light 'Plane Works is being exhibited on the stand of S. T. Lea, who is sole concessionaire for the British Empire. The machine is already well known in this country, having visited a number of light 'plane meetings and clubs throughout the country. It is fitted with the 40 h.p. 9-cylinder Salmson engine. The L.25 is a two-seater dual control light 'plane, of the low-wing monoplane type. Both fuselage and wings are plywood-covered, the wings from rear spar to trailing edge being, however, fabric covered. The wing can be dismantled from the fuselage as a unit. The seating accommodation is the usual, with two cockpits in tandem. The undercarriage is of the split type. With a petrol capacity of 22 gallons, the range of the Klemm L.25 is approximately 600 miles.
   The tare weight of the L.25 is 600 lbs., and the disposable load 400 lbs., giving a gross weight of 1,000 lbs. The top speed is 85 m.p.h. and the landing speed about 30 m.p.h. The dimensions are: Length, 23 ft. 8 in.; wing span, 42 ft. 8 in.; wing area, 215 sq. ft.

Flight, April 1930

AIRCRAFT FOR THE PRIVATE OWNER

KLEMM

   THE Klemm L.25 two-seater light monoplane is being handled in this country by S. T. Lea, of 141, New Bond Street, London, W.I. It is, of course, a German-made machine, and comes from the Leichtflugzeugbau Klemm G.m.b.H. Boblingen, Wurtemburg. It was originally designed as a very light machine with the 40-h.p. Salmson radial engine, and in this form has achieved a large number of notable performances. Many machines have been sold in this country with this little engine and its performance with two persons is astonishing. Our upper photo shows this type.
   Lately, however, a slightly larger model has been made to take the 65/82-h.p. Siemens engine, or the 85/95-h.p. "Cirrus III" engine. A three-seater version with this latter engine is now in this country, and is said to have a very good performance indeed. It is shown below.
   Arrangements are now being made to manufacture the "Klemm" in this country, for which purpose a company has been formed, and factory sites are being considered.
   As a low-wing monoplane, the "Klemm" offers an exceptional view, both for the pilot and the passenger, and it is a very comfortable machine. The low wing loading and consequent low landing speed rather tend to make it not quite ideal on a very bumpy day, but under normal conditions it is extremely easy to fly. The whole machine is of ply-wood construction, so that there is never any truing up to be done. The wings are quickly detachable by means of vertical pins at the roots, and when detached, they may be stowed in sockets provided so that they lie vertically against the sides of the fuselage. This is claimed as a very simple operation, and one that can be done in a very few minutes, and it certainly has the advantage that with the wings in this position, the machine can be stowed in a very narrow shed.
   The "Klemm" is the best known of the many Continental-built light planes, and has proved itself in every way a private-owner's machine. The ply-wood construction ensures that the machine is sturdy, and with even the tail surfaces thus covered, there is very little that can be damaged by inquisitive spectators.
   Its large span makes it an efficient flying machine with low induced drag, and it is quite controllable below the stalling point, so that private owners need have no fear of stalling inadvertently.

Flight, October 1931

AN INTERESTING LIGHT AIRCRAFT

   AN aircraft which, although of foreign design and make, has already sold in quite considerable numbers over here is the Klemm. We have described this machine from time to time and have illustrated it with many and varied engines fitted to it. One of the latest forms is that with the Hirth engine. We recently took the opportunity of trying this machine for ourselves, and found it to be extremely fascinating. The motor could hardly be smoother, and is apparently exceptionally economical,, for Mr. Rogers, who demonstrates Klemm aeroplanes for S. T. Lea, Ltd., of 141, New Bond Street, W.I, tells us that the fuel consumption is only three gallons per hour, while the oil consumption is at present almost negligible. After trying this machine we cannot help feeling that there is a very definite future for machines of similar type built in this country. Possibly the plans which have been laid for a company to manufacture Klemms themselves, or else the new de Havilland "Swallow" will meet the demand, for a demand there certainly is.
   The Klemm is the type of aircraft which immediately inspires anyone with confidence, and we imagine that for club flying it will be hard to beat. For such a purpose several features will, of course, have to be altered. For example, the undercarriage looks somewhat too light to stand up to the hard wear of teaching people to fly, but the flying qualities of the machine itself cannot but inspire confidence in any beginner, particularly if those beginners are, as is already the case at many places, glider pilots who have now turned their attention to power-driven aircraft. The Klemm is very like a glider to fly, and, due to its efficiency, has an exceptionally flat gliding angle. It is also almost impossible to stall in a dangerous manner, and, even with the stick pulled right back, does nothing more than sink to an even keel and picks up speed immediately. It is naturally very different from such machines as the conventional single-bay biplane, and has, therefore, to be flown differently, but once those small differences have been mastered, it is one of the simplest and least tiring machines of any. Another point in its favour is that the boxed plywood low cantilever wing is an excellent safety factor in a crash. One has only to look at that accident at Croydon recently, when a Klemm of the B.A.T. Co., Ltd., went up with two Press photographers and when some 60 ft.,off the ground the pilot discovered that the ailerons were either not connected up or else connected up the wrong way, we forget for the moment exactly which it was. However, the machine crashed from that height and completely demolished both wings and the undercarriage, and, of course, the engine and front part of the fuselage, but the occupants were not hurt at all! Such a crash is one which, of course, could have been avoided, for most pilots invariably try their controls before taking off, but on this occasion the pilot in question appears to have forgotten this simple precaution.
   There is a further interesting development in connection with the Klemm, and that is a machine even lighter than the model which is fitted with the 50-h.p. Salmson engine. This was, we understand, built in the first place as a machine which Herr Klemm's son, age 9, could fly round the aerodrome with safety. It is a similar type of aircraft, but has a wing span of some 54 ft., resulting in a low-landing speed of about 8 m.p.h. and a cruising speed of about 35 m.p.h. The engine is at present a small 2 cylinder of the motor-cycle type. The development which is expected is that an aircraft of this type will have some form of retracting gear for the propeller so that glider pilots may rise under their own power to suitable cumulus clouds, then retract their propeller and proceed to soar, and if, as it is hoped, this machine sells at considerably less than ?200 there is no doubt that its appeal will be very strong indeed to glider pilots and clubs and those who want something slow, safe and easy to fly.
   In conclusion, there is one fallacy we should like to point out, and that is that Klemms are invariably slow. This has come about from the fact that the Klemm was first marketed with the little 50-h.p. Salmson engine. Naturally this model is slow, but its lack of speed also makes it extremely safe, and therefore has its appeal to a large number of people. Latterly, however, engines of various powers have been fitted, and the latest is one with a Gipsy III engine and somewhat clipped wings, resulting in cruising speed of somewhere about 112 m.p.h. There are also rumours of a mail carrier which has the 200-h.p. inverted Argus engine, with a cruising speed of over 130 m.p.h. The existing three-seater Klemm with the inverted Hermes engine is already being used in Africa for mail carrying purposes, and seems extremely efficient for the job, having a fuel capacity of over 40 gall, and a payload of over 1,000 lb.

Flight, January 1932

For a Quick takeoff

   KLEMM aircraft have consistently been seen in this country fitted with many different kinds of engines. When they first appeared the little 2 cyl. 30 h.p. Daimler engine was fitted, after which the 40 h.p. 9 cyl. French Salmson was used, while other versions have often been seen with 80 h.p. Siemens, 95 h.p. Cirrus III, as well as the larger Hermes, Gipsy II, and Gipsy III. The latest combination, however, is that which has been effected by the Klemm Works to the order of Mr. A. B. Gibbons, and consists of a standard Klemm with the English built 7 cyl. 75/80 h.p. Pobjoy engine. We have always felt that this was a combination which would provide a really fine aircraft for the private owner, and this appears to be the case. The Pobjoy engine, being geared, allows the use of an airscrew of high efficiency and large diameter, and moreover one which "bites" immediately the throttle is open, thereby assisting the take-off very materially.
   In a recent demonstration of this machine Mr. Gibbons took off from the tarmac in front of the service hangars at Stag Lane, a feat which he was allowed to do through the courtesy of the London Aero Club and De Havilland Aircraft, Ltd. On this occasion the wind was nearly directly towards the hangars, and as the hangar doors were shut there was a strong down-draught on the machine for quite a considerable distance of the take-off run. Unfortunately the wheel brakes were not in the best of order and did not allow Mr. Gibbons to rev. up the engine to any great extent before starting his take-off run. This defect, however, really enhanced the value of the demonstration, for it showed very forcibly that when the brakes are in order a take-off should be possible from the smallest of fields. Owing to the creeping of these brakes on this occasion accurate measurements were not possible, but our rough ones gave a distance of between 15 and 17 yds. from the start until the wheels were clear, which means that Mr. Gibbons was actually flying before he reached the end of the tarmac.
   The power-weight ratio of this machine is very good, as, of course, readers of FLIGHT will know that the Pobjoy engine gives an exceptionally high h.p. for its low weight, and this, combined with the low wing loading of the Klemm, gives an extremely good climb. Safety is one of the features which Herr Klemm has constantly striven after, and we venture to think has attained as much, if not more, than many others ; anyhow, although he has sold some 500 Klemms, there has been only one fatal accident in connection with them as far as we are aware. The model under discussion has, of course, the latest design of rudder wherein the area has been increased, and this enables the pilot to hold the machine in a side-slip without the nose dropping, as was the case with the old Klemms with their little square unbalanced rudders. On the flying characteristics we need not enlarge to any great extent, for our readers have been told all about these on many occasions. Put briefly, the Klemm is almost spin-proof, while in the present model the quick take-off, together with the extremely low landing speed and the fact that lateral control is retained even when the stick is pulled back, so that the machine is descending at a very steep angle of glide, all combine to make it one of the pleasantest aircraft we have flown. The low wing construction provides very good visibility, safety in minor crashes, and ease of handling when on the ground under conditions when any biplane or high-wing monoplane might be blown over. This Klemm Pobjoy has caused considerable excitement not only in England, but also in Germany, and the following figures justify this. These were obtained during the type test flight, when the machine was piloted by Herr Kirsch, the Klemm Company's pilot. It should be noted, however, that they have not yet been confirmed by the D.V.L. :-
   Take-off run (using wheel brakes while revving up the engine), solo, 9-15 yd.; loaded (5 hr. fuel, passenger and luggage), 25 yd. Climb to 2,380 ft.; light, 3 1/2 min.; loaded, 4 1/2 min. Climb to 19,000 ft.; loaded, 46 min. Estimated ceiling, 21,000 ft. Cruising speed at 1,500 ft., 3,000 r.p.m.; 97 m.p.h. Top speed, 3,400 r.p.m.; 108 m.p.h. Landing speed, 23-25 m.p.h. Weights: machine empty, 750 lb.; loaded, 1,480 lb.; aerobatic loading (class S.4.K), 1,435 lb.