6th February


The Sedbergh has a test permit until the 13th February

This glider has been maintained to BGA standards

Nok Airport operator Yves, and Nympsfield instructor David

7th February

Tony gets to soar the T21B on Thursday when the conditions were good enough to find a thermal or three. You need goggles against the blast behind the Cub, but not to soar.


The darker ground above centre of this picture was producing lift

The English are:

Eccentric people and we all like to bring a bit of the England we know where-ever we go.
It might be custard and trifle, scones and jam, or in this case a Slingsby T21B and a de Havilland dh82a Tiger Moth.

But many countries are not entirely compatible with English sensibilities and so it's difficult to get a pint of real ale in an arab country, and in Thailand it's difficult to fly one's vintage glider and one's Tiger Moth.
Difficult but not impossible.

The 52 inch pitch metal prop was replaced by a 44 inch pitch wooden propeller, but the rate of climb did not improve much. This is a broad chord propeller; perhaps it's more effective at low towing speeds.

Tony is responsible for bringing in the T21B and the dh82a to Thailand. It's great that he is able to take part in the gliding he'd worked so hard to bring to Thailand

My job is to tow the Sedbergh at it's ideal speed; 55mph! I used one stage of flap and testing seems to indicate this gives a better rate of climb at 55 mph than with no flaps.

The takeoff was with a 2 to 3 knot tailwind, but the options if anything goes wrong are better in this direction (16).

The grass was used for landing both the tug and the glider. This meant coming in high and slow then steep and 55 mph IAS in the tug to avoid snagging the tow rope on the fence which could have led to a very short landing!

Tony's flight was delayed 15 minutes due to traffic at Chiang Mai International, and rather than being allowed to climb to 3,000 feet ASL (Nok is 988 feet ASL) we were limited to 2,000 feet so regretfully I waggled the wings and the glider released.
But I released them over an area where there was thermal activity and so the glider was able to soar for a longer flight.

The tug pilot experience has been an interesting one. The takeoff run is longer and the Cub gets airborne at 45 mph or so, then I accelerated (so to speak!) to 55 mph to climb (in a fashion).
The RPM was only 2,200 in the climb, something I was concerned about, but then the climb is at a much lower speed than that for best rate: Vy = 75 mph, [Vx = 45!].
I monitored the oil pressure and temperature in the climb especially as it's warm here, and then took it easy on the engine for the descent.

I did four tows on Wednesday, and five tows on Thursday. Six tows were to 3,000 feet QNH, 2,000 feet AGL and these took between nine minutes and fifteen minutes. Most were at nine minutes.
I generally stayed close to the airfield and looked for some lift to help out.
I did turns both right and left and as the 'student' built experience I increased my bank in the turns.
They got me back here and there; note how I am left of the centreline in the heading picture while the glider is to the right!
You don't have as much authority if the glider is going to one side, your rudder is not powerful enough to stop you going the other.
Likewise the elevator, if the glider goes high it can dump you nose down, and you better have your release ready for this!

12th and 13th February 2013

On Tuesday 12th February I did five tows and Yves did two.
On Yves first tow I was flying the T21B and nearly got too high on the takeoff!
You need a lot of forward stick pressure to keep the nose down in the T21B on aerotow.

This past week has been a military execise with USAF KC130 Hercules aircraft flying around at all levels.
This meant we were grounded for three hours on Wednesday, but on appeal this was reduced to one and a half!
We were only able to complete four tows.
On the second tow ATC restricted my altitude due to the military operations, the glider released downwind of the field but within range of the field. I saw it soaring in lift as I returned to the field.
Later I looked for the glider from the ground... No sign of it; oh dear! If it had landed out this would be a crash in Thailand and a big investigation would take place.
I was at the point of making a flight plan for a local flight in the Cub to see if I could spot their landing place when the T21B came sailing by... They had a long soaring flight.
After the grounding we were only allowed to climb to 2,000' QNH, 1,000' AGL for the remaining two flights.
All was well with the world and now the T21B is grounded awaiting the issue of it's full CxA.

Back to MPAviation