GLIDER CHRONICLES 2011 – May 27th : Fire Thermal & Solo Aerotow.

This day had a surprising morning soaring flight in overcast conditions thanks to a bonfire on a farm, plus a couple of solo aerotow flights, representing a significant milestone on the way to being able to fly the single-seater glider fleet.

To give an idea of the cloud cover here is a picture – though taken 2 days later on the Sunday but with similar conditions.

K13 Launch on a cloudy day.

Fri 27th May: Conditions: Moderate cross wind from the north-west.

Instructor notes 1:

  • Check flights in K21. Run out of height + (winch) power failure well handled. Cleared for solo in crosswind conditions.
  • This was followed by 3 solo flights from the winch in overcast conditions so no sun reaching the ground. However, someone on a farm had lit a fire which triggered off thermal activity thus allowing me on one of the flights to scratch around until I managed to find a 4kts up thermal which took me up to cloudbase at 2000ft. This resulted in a flight time of 31mins which was above the threshold of half an hour for counting as a soaring flight from the winch.

    So once again I was feeling very pleased with myself given that it was completely overcast. Also to add to the big headed feeling, I saw someone else get an aerotow above me into the same area around the fire. However they were not able to connect to any lift and thus had to land before me.

    Instructor notes 2:

  • Aerotow well flown including out-of-position and boxing the tow. 2 solo tows well handled.
  • By the end of the day, although there was now some sun, the lift was very weak indeed. However it was nice to carry out a couple of solo aerotows to get these under my belt.

    Explanation of Boxing the Tow
    This is an exercise that is used to show that you are proficient at handling the aircraft during an aerotow. (An aerotow is where the glider gets pulled along behind a powered light aircraft called the Tug)

    Boxing the tow involves first descending lower than the tug aircraft. This requires the pilot to control the glider as it passes through the turbulent air from the propeller of the tug (the propwash) until it reaches the calmer air below it. You then have to fly the aircraft out to one side and hold it a short while. Then, staying on that side, fly up to level with the tug aircraft or slightly higher and hold… Then fly across to the other side of the tug at the same relative height and hold… Then again staying out to the side, descend to a height below that of the propwash and, you guessed it, hold… Then return to the starting position below the propwash before returning to the normal tow position behind the tug.

    If you do this well you will have described a nice rectangular flight path around the tug’s propwash, hence the term: Boxing the Tow. Great fun.

    Next step is to move onto getting ready to fly the Grob102 single seater, also known as an Astir.

    Grob 102 picture from the Imperial College Gliding Club archive.

    Follow this link to the Imperial College Gliding Club archive to see the gliders that they have owned throughout the years.

    Coming up:
    Lasham Regionals Competition and flying log from the same wonderful day, once the weekend rain had passed.

    Comments welcome. Let me know what you think...

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