Post: <font color="#CCCCCC">Post Reply</font>: <b> Runway v Dirt/Sand/Salt Flats for record breaking. by Mick Mitchell </b>

OriginalMessage: Runway v Dirt/Sand/Salt Flats for record breaking.
Just thought I would put pen to paper on the debate re high speeds on runways v dirt/sand/salt flats. As a simple land yacht pilot who sails ‘Class 5’ and ‘Standarts’ most weekends of the year on an ex USAF 8th Army airfield in England, I am not often involved in speeds much over 50/ 55 mph but as a British Federation National Instructor I do cover the effects of the varying apparent wind with regard to yacht speed and direction in our training courses. The main disadvantages of trying to obtain high speeds on a runway are that the runways are usually built a) parallel to the prevailing wind and b) in a straight line. The effects of these constraints are that suitable winds are unusual and when the direction is OK the apparent wind direction quickly moves to, virtually, a head on condition. This forward movement of the apparent wind direction and the straight runway has two effects a) the required angle of attack of the sail (or wing) cannot be obtained and b) the sail drag quickly becomes higher than the propulsive force and as the centre of lift/drag of the sail is one third to half way up the sail, this tends to lift the front wheel with ‘Brown Adrenaline’ producing effects in the pilots underclothes.This I know from experience. The resulting rapid deceleration and change of dirtection then causes the apparent wind to back off far to quick for the pilot to sheet out fast enough resulting in a spectacular hike. All good and enjoyable stuff but not conducive to record breaking. I would think that the disadvantages of having to sail on a dirty old dry lake or salt flats with strange men in funny hats criticising your best efforts, would be outweighed by being able to select a course to suit the wind direction with plenty of room so that you can gently bear away from the actual wind direction so as to be able to obtain the best angle of attack and hence get the best possible performance from the sail/wing. Also as long as the sail is producing more lift than drag the front wheel will tend to be held on the ground, keeping the yacht under some sort of control and hence decrease spent time washing dirty underpants. So Richard I wish you the best of British and trust that you will be able find suitable sponsers to enable you to meet you dreams.

OriginalMessage: Runway v Dirt/Sand/Salt Flats for record breaking.

Just thought I would put pen to paper on the debate re high speeds on runways v dirt/sand/salt flats.

As a simple land yacht pilot who sails ‘Class 5’ and ‘Standarts’ most weekends of the year on an ex USAF 8th Army airfield in England, I am not often involved in speeds much over 50/ 55 mph but as a British Federation National Instructor I do cover the effects of the varying apparent wind with regard to yacht speed and direction in our training courses.

The main disadvantages of trying to obtain high speeds on a runway are that the runways are usually built a) parallel to the prevailing wind and b) in a straight line.

The effects of these constraints are that suitable winds are unusual and when the direction is OK the apparent wind direction quickly moves to, virtually, a head on condition.

This forward movement of the apparent wind direction and the straight runway has two effects a) the required angle of attack of the sail (or wing) cannot be obtained and b) the sail drag quickly becomes higher than the propulsive force and as the centre of lift/drag of the sail is one third to half way up the sail, this tends to lift the front wheel with ‘Brown Adrenaline’ producing effects in the pilots underclothes.This I know from experience.

The resulting rapid deceleration and change of dirtection then causes the apparent wind to back off far to quick for the pilot to sheet out fast enough resulting in a spectacular hike. All good and enjoyable stuff but not conducive to record breaking.

I would think that the disadvantages of having to sail on a dirty old dry lake or salt flats with strange men in funny hats criticising your best efforts, would be outweighed by being able to select a course to suit the wind direction with plenty of room so that you can gently bear away from the actual wind direction so as to be able to obtain the best angle of attack and hence get the best possible performance from the sail/wing. Also as long as the sail is producing more lift than drag the front wheel will tend to be held on the ground, keeping the yacht under some sort of control and hence decrease spent time washing dirty underpants.

So Richard I wish you the best of British and trust that you will be able find suitable sponsers to enable you to meet you dreams.

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