Down Memory Lane - From the Log Books #4

[Guest TOSGcentral]

Now for a look at some of the German post war training types. As I learnt to fly in Germany I was brought up either on or with them so they have a fond part of my memories and between them and flying with the UK types in the RAFGGA clubs – the variety of types game me an unusually accelerated introduction to visually assessing how an aircraft was likely to behave before I even got in it.

 

 

Some Background.

 

 

Post war Germany settled down to two main manufacturers (Schleicher & Schiebe) dominating basic supply to clubs. They concentrated on producing ‘matched fleets’ that would take a student progressively from the basic trainer into basic single seaters and then to more useful performance single seaters.

 

 

Geographically speaking those two main manufacturers split Germany between them. If you went and flew down the South end (Barvaria etc) you would most likely find Bergfalkes. Up North and around the Ruhr then it would be Ka 7s and so on.

 

 

Sure, there were some efforts to penetrate the market, some of which were a bit wild and woolly, but with teutonic efficiency the Germans sorted things out. This left some highly specialised firms, usually working in close contact with major universities , who produced the cutting edge world beating single seat competition sailplanes that were primarily private owner orientated.

 

 

But back in the club training area there appears to have been some additional type parallel thinking going on. This encompassed the early post war years where certainly there was the know how to produce sophisticated trainers but there was also a pressing economic need to supply cheap little trainers that would work and get people into the air.

 

 

So we had things like the DopperlRaab (subject of an earlier post) but in the factory production area we had similar sized little two seaters such as the Ka4 and the Specht.

 

 

So we have to deal with both and that makes the story not quite so easy to write in chronological development terms for the Ka4 was nowhere near the performance of the earlier Ka2 – different horses for different courses – or wallets!

 

 

Schleicher and the Ka Series Trainers.

 

 

The manufacturer’s premises nestle at the foot of the world famous gliding hill site of the Wasserkuppe. They have been there for decades and for decades their chief Designer was Rudolf Kaiser. Although many of the Schleicher types have names (RhonAdler – Rhon Eagle) in practical terms they were referred to by their type number and these included the Kaiser acknowledgement. So you got, for example, the Ka2 which was actually named the RhonSchwalbe (Rhon Swallow).

 

 

Ka2.

 

 

I came to this type early as a student and then it was very much a ‘super ship’ when it infrequently visited. Later I was to instruct in them

 

 

The Ka2 started the main post war training range of Schliecher training models. The type first flew in 1951. In fact it was a bit of a lead sled as it was quite large and heavy but had only a 15 metre wing span. Nevertheless it flew and soared well and was a most adequate trainer with good stall and spin characteristics.

 

 

The airbrakes were a tad too powerful perhaps and care had to be exercised with students messing about with them too much near the ground. There was plenty of motivation to do this as there was no springing and the mainwheel was just about below the instructor’s spine – so the instructor copped all of the vertical landing shocks.

 

 

A tandem seater with a high wing, all wood, with a monocoque fuselage - the type reflected some economic necessities . There was no shortage of skilled airframe woodworkers in those days and wood was easier and cheaper to come by than metal, so an all wood commercially produced machine back then was not quite the challenge that is today.

 

 

The two main shortcoming of the machine was the very small Perspex panels rived together to form the hood. The front part swung open to one side and the rear hinged upwards giving reasonable if less than totally elegant access to the rear seat. So visibility from the front was not quite as good as it may have been and was bloody ghastly from the back!

 

 

The rear occupant had his/her head ‘blinkered’ by the two formidable sized wing roots on either side. Sideways vision was limited to squinting through the top clear overhead panel when the aircraft was banked and turning, or bending forward and peering below either wing when straight and level or to view outside the turn. The forward vision was a tunnel of all these small Perspex bits and pieces!

 

 

Some of this problem was alleviated by the ‘Swiss Hood’. This was a fully blown bubble that you sawed in two and fitted the original canopy frames to. It improved vision no end but still left the instructor trapped in the visual dog box of the wing roots.

 

 

My memories of the Ka2 remain fond although I was uncomfortable in it when wrapped up in crowded skies and occupied thermals.

 

 

There is to my knowledge one Ka2 example in Australia that was rebuilt and operated for quite a few years by Mike Valentine. I do not know where it is now though.

 

 

Ka7.

 

 

This type became Schleicher’s mainstream volume trainer. It was a refined version of the Ka2 with wing span expanded by 1.2 metres. The main difference was that the fuselage became a tubular steel, fabric covered framework.

 

 

On the other hand the Ka7 inherited just about all of the faults of the Ka2 and some of these were even magnified.

 

 

Visibility was the same and was cured (as much as may be) by the bubble hood. The type preserved the large front skid forward of the main wheel and this skid routinely took a lot of ground shocks where there was insufficient airspeed to keep the machine balanced on the mainwheel – which remained unsprung. For the instructor this gave potentially extreme physical landing loads as the aircraft was also heavier so great care had to be exercised both in pre-briefings, overall exercise management, and monitoring of student stress levels.

 

 

As an example of damage. When I was working at Benalla we had a visiting Ka7 come in for a week of flying with us (as we flew all week) under the charge of a small group of really nice young guys who had enthusiasm bubbling out of them.

 

 

I asked their permission to take a look around their aircraft and the first place I went to was the skid support tubes under the seats. Sure enough the main frame had completely severed in four places and the broken ends were red with rust!

 

 

I had to ground the glider pending repairs (big job that) which ruined their holiday. It was not really their fault- their club did the maintenance and they assumed the aircraft was OK. So I spent a bit of time with them after work on a white board covering pilot responsibility and daily inspections – particularly applicable to the Ka7. Experience always costs!

 

 

The Ka7 had, like its predecessor, devastatingly powerful airbrakes – perhaps too much so! The following little tale illustrates this.

 

 

The British Gliding Association (BGA) have Test Flight Groups dotted around the country whose task it is to examine all first of types coming into the country to ensure that they did what they were supposed to do. Part of this procedure involves the airbrakes in two prime areas. Firstly, for cloud flying certification (at that time) the airbrakes had to be ‘t.v.’ (Terminal Velocity) meaning they had to constrain the glider at or below Vne when in a vertical dive. If you lost control in cloud then all you had to do was open the brakes fully and you could not break up the machine.

 

 

This therefore involved actually opening the brakes at Vne to check that this could be done. That is no problem on the Ka series trainers with the Schempp Hirth double paddle brake system. Once you unlock them air pressure blasts them open and you require considerable force to control them. The test pilot did not know this so the airbrakes instantly extended fully and the airflow pressure bent all four paddles backward. This left the machine with powerful airbrakes, fully deployed and jammed open!

 

 

This particular Ka7 was privately owned and the owners were not at all amused so they took their toy back and the test flying never got completed on the Ka7. Or it did quite a few years later when Lasham bought as couple as back-up trainers. There was only the spinning to do so we knocked that off easily and everything was great.

 

 

ASK13.

 

 

This is my all time favourite gliding trainer. It does everything you want! A good glide, good sink rate, comfortable, sprung wheel, excellent visibility, docile but convincing stall, spins well and will stay in, plus it ground handles well so is not overtiring to handle for repeated ‘string fling’ launching and no soaring. I have done probably 5 or 6 thousand instructional trips in them.

 

 

The ASK13 was a re-worked Ka7. The wing stayed much the same but copied the layout of the long established Sheibe Bergfalkes and was dropped to the mid wing position, thus was given a bit more dihedral to preserve the stability. This gave excellent rear seat visibility under the once piece blown bubble hood.

 

 

Both cockpits (especially the instructors) are roomy with nicely moulded seats and adjustable rudder pedals.

 

 

In common with the Ka2 and Ka7 the machine has very powerful ‘suck open when unlocked’ airbrakes. It also has a few construction geometry refinements that often go unnoticed. The push rod and bellcrank arrangements are set so that fore and aft movement of the stick also bilaterally slightly raise or lower both ailerons. This smooths acceleration and deceleration and in fact adds greatly to the ‘nice’ control feel the glider has.

 

 

As an instructor I have always been a very pro spin training on gliders and I always needed machines that would spin convincingly without much messing about. The ASK13 spins beautifully as the following two little tales will relate.

 

 

The Lasham public ab-inito courses were two week affairs of five days each and we had (weather permitting) about a 90% success rate for first solos, but without making it a treadmill affair – the graduates could go back to their clubs and those clubs would have solid material to continue developing.

 

 

The first week was in the SF25B or T61A Falke motor glider where stalling and wing drops were covered fully. The following week in the ASK13, off auto tow wire launch, stalling and early incipient spins were consolidated – usually between 1300’ and 800’ agl

 

 

Thursdays was full spin day and we used aerotow to 2500’ (which gave the course members a bash at aerotowing as well). A few half turn incipients were experienced, a one turn full spin was demonstrated and the student was talked into spinning the glider for one turn and recovering by themselves.

 

 

On one occasion a seemingly normal student lost the plot completely on his own attempt. He got the full rudder on OK but instead of relaxing the stick back pressure he went for ‘text book’ full spin recovery and the stick hit the front stops.

 

 

The ASK13 stopped spinning instantly, went through the vertical and was beginning to outside loop onto it’s back. This was depressing! I could not let the negative G continue or we would lose the wings anyway and if she did go fully inverted there was not enough height left to pull through in a half loop.

 

 

I ignored the stick and went straight for the airbrakes. We were well above Vne by then and my mind was full of the story of the Ka7 test flight related above. The design must have been improved as the brakes did not snap off nor did they bend backwards so I was later able to close them. We had just enough height to limp back and flop over the fence to a normally not often used part of the airfield.

 

 

I can give you some factual data on the ASK13’s height loss in a one third turn incipient spin from entry to recovery. It is almost exactly 350’, but that is if you are fully revved up and very current on type. For a pilot losing control in a final turn by accident then you will need every bloody inch of the mandatory minium 500’ final turn height – that is why the requirement is there!

 

 

350’ ag; was the height I initiated a critical decision height recovery check for a student from a simulated cable break on an auto tow launch – and we missed the ground by about 2’ at the bottom of the recovery from what then happened!

 

 

Once again this student panicked or something and instead of repeating the normal procedure he already had plenty of practice at, he hauled the stick fully back in already a 45 degree climb and applied full left rudder. The ’13 span instantly.

 

 

I prised the little bastard off the controls, recovered and we just got around the bottom!

 

 

Damn! I love those ASK13s – I have never had one let me down!

 

 

Next time we will take a look at Schiebe’s Bergfalke offerings that were in direct competion with the Ka series of trainers.

 

 

[Guest coaltrain]

Great read!

 

I learnt to fly in the K13 and K7, fantastic gliders. When landing on a still day, particularly the K7 I can remember you could often bring the glider to a fullstop with wings level before she would slowly lean to one side and put a wingtip on the ground.

 

 

[Guest weekendwarrior]

Had my first solo glider in a K13 at Camden a few weeks ago, it is still THE trainer :thumb_up: