GLIDER CHRONICLES 2011 – August 13th: Modern Beauties – Part 1

Recent flying has been hampered by the weather, but I have managed to convert myself to flying the newer Discus single seater gliders, of which Lasham has three. These are beautiful fibreglass and carbon fibre aircraft which were initially built in 1984.

For local soaring flights I had managed to get all the necessary “qualifications”, apart from the final check flight:

1: Bronze ‘C’
– Yep. Got that.
2: 20 hours solo flying, including 10 hours in the Grob102 or similar (i.e. a glas fibre single seater)
– Yep. Got that too.
3: Briefing and check flight with full cat.
– Don’t have that – so this was the day to go and get it.

What on earth is a “full cat”? This is a Full Instructor or FI as the BGA calls it. There are various categories of instructor ratings from those who are “Basic Instructors”, usually the folk who do the trial flights, up to the “Full Instructor” rating that is the person who needs to do this check as well as be on hand to run a launch point.

So – given that there had been a dearth of good soaring days, it was time to get myself converted, although I am still not quite ready to go cross-country as yet. I am only able to do local flights closer to the airfield. For cross country I am going to need to get what is called a Cross-Country Endorsement. This is part of the Red Card and will need two flights with an instructor to cover field landings and navigation. Hopefully coming soon!

Anyway – on to the day’s proceedings.

A wet and dreary Lasham after the rain the night before. Not looking great.

As you can see the morning started with water on the ground since it had been raining copiously the night before. It had also been a hectic week for me at work so it was a difficult thing to raise my sleepy head to get to Lasham when I could see it was not set to be a great day. The forecast was for overcast skies which, as you can see, turned out to be correct. However, I was determined to get the conversion done if possible.

After having got an ASK21 out to the launch point and having grabbed an instructor, the CFI recommended that we should really get the Duo Discus trainer out. This is the 2 seat version of the Discus, and as I found out later is an absolute joy to fly so the initial exasperation at having got the wrong glider to the launch point was soon overcome by the fun of playing with a new toy! Also the K21 would not go unused so I was not too bothered. I always like to feel I keep the “social credit” in the club topped up.

One of the things I really like about this sport is the beauty of the flying machines. They are lovely to look at and I can sometimes quite happily just sit there gazing at them. The next thing I like to do is go up and touch them – usually done under the disguise of cleaning the glider! Of course I also then do the nerdy thing of looking into the cockpit and checking out the toys – whoops sorry – instrumentation, in them.

I suppose the closest thing for me in a powered aircraft would be the Spitfire, but gliding is cheaper and not so noisy! Plus I can have that supercilious grin of feeling more “green”, just.

Lasham Discus SH4.

The Duo Discus. Love those swept wings.

The recent Arcus, but can't afford this.

You can see from the accompanying shots that both the Discus and the “Duo” have swept back wings, in common with many modern gliders. This is to reduce what is called induced drag. I have also included a shot of the most recent glider from the same company, the Arcus, which I happened to see at a recent competition day at Lasham. If you look you can see that the Duo and the Arcus have the same fuselage sections although I only found that out from the Arcus’ Wikipedia entry.

Explanation: Drag

Whether you are designing an aircraft or a racing car, trying to swim faster, or leaning into a strong wind, you will be familiar with drag. Drag is the force that tries to stop you moving through a fluid medium, e.g air or water. But just considering aircraft, drag is generally broken down into two main types: Parasitic Drag and Induced drag.

Parasitic Drag is the drag that happens just because you are moving through the air. Just like when you hold your hand out of a moving car’s window, flat on to the airstream. By streamlining the shape you can reduced this drag. Hence the reason gliders (and fast fish!) have pointed noses. This type of drag increases the faster you move through the air.

Induced Drag is rather more subtle and happens as a by-product of the lift generated by the wings. While flying, as the airflow leaves the ends of the wings it becomes a vortex. [Good image here and you can see my previous photo]. This vortex causes drag on the aircraft and so a lot of research is done to make glider wings that produce as little drag as possible. This is also a reason why you will see winglets on many aircraft, from gliders to airliners. This type of drag decreases the faster you move through the air.

That is but just a quick introduction to the world of drag.

The Discus panel. Clear Nav in centre.

Once the Duo Discus had been checked over we brought it out to the launch point ready for an aerotow and I climbed in to familiarise myself with the cockpit layout. OK. Read that as: I climbed in to play with the GPS system. The Duo and the single seater Discus gliders all have a “Clear Nav” GPS system which is a real help when flying. So, yours truly being one of the original nerd types, I am able to have a wonderful time both flying newer gliders and playing with computers. Great fun!

For the pilots among us, at the time of writing the online Clear Nav manual can be found here. I find this more useful than the PDF version of the manual.

When I had familiarised myself with the controls I climbed out of the cockpit. Wow. It is really deep and I was pulling muscles in my arms I didn’t know I had. Looks like more trips to the gym are required.

Once out of the cockpit I was all raring to go and so . . .

We waited . . .

Waiting . . .

And waiting . . .

So there I was – I had the glider, the instructor was there, the tug plane was available, but the English weather was not cooperating. The cloudbase was too low at around 1500ft for an aerotow to be worth the money.

After my initial accommodating behavior of just waiting 30 minutes and chatting at the launch point and being sociable (I am a very accommodating and sociable person!) I got fed up with waiting and said to my instructor: “Chris I am fed up with this – lets take a winch launch”. So we moved the glider to the winch queue and we took a wire launch.

I could notice immediately just how lovely she was to fly (yes the aircraft are always ladies). We even managed to contact some weak lift and stayed airborne for 11 minutes. Not too bad for a winch launch on an overcast day. By the time we had returned a report came back that the cloudbase had risen and so we were ready for the aerotow.

When flying the single seater Grob102 or Discus the first launch must be an aerotow since it is gentler than a winch launch. For the Discus, the elevator control is more sensitive so the check flight is best done with the Duo Discus. I must admit that I didn’t have a problem with the Duo, but definitely noticed the difference with the single seater.

As I mentioned before I found the Duo a lovely glider to fly. The main foible was the undercarriage. My instructor, Chris, mentioned that you really needed to make sure that it was locked down since the lever could come out of the détente. Also the instructor is not able to lock the lever from the rear cockpit – he has to have faith that the person in the front has done so properly. To try and reassure Chris I had locked it properly I gently thumped the lever to the cockpit wall after I had put the undercarriage down!

Again we found some weak lift but I was mainly concentrating on getting used to the handling. After giving myself more space in the circuit thanks to Chris’ advice, we landed back and Chris signed my log book with the words:

Check for solo Discus. OK. Well handled.
Also, since the sign-off for the Discus is on the Yellow Card I went back to the office and he signed that entry on the card.

Great! Another milestone reached.

It may be a naff (technical term meaning Not Actually Fully Functional) day weatherwise but I was checked out for the Discus. The only thing left to do now was to go over to the clubhouse and find an instructor prepared to brief me about rigging the Discus. Now this is a whole tale in itself and I think I shall leave it to the next posting . . .

Coming soon – the tale of the lesser spotted Discus rigging briefer and yours truly apologising profusely.

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