Tips on circuits

[Low Level]

As I am new to this - please explain propwash to me. I know what it is, but thought that it is something that only has an effect, like about 10 or so meters - depending on the size - behind the aerie.

How does it affect the plane behind, or is it only trikes that suffers ?

Is it only on ground level ?

In a previous threat it appeared to me like it is hanging in the air for a while, like a babelaas fart.

P.S. Maybe this must be a new thread - don't want to hijack this one.

[DieselFan]

I was flying with Cobra passed Rietvlie, the first time I encountered propwash in my own plane. Weather was calm, he was about 200-300m away I was kinda behind him, suddenly left wing dropped sharply and plane pitched down, was easy enough to recover from although I didn't put it down to propwash till my second outing with Cobra. Again almost 250-300m this time with wind and EXACT same as before happened, my PAX grabbed me rugby style. It was then I thought about previous excursion. If I was close to the ground when that happened I'd most surely be dead - but with height recovery is easy almost like a stall.

In 2 weeks I've had it 4 times and in two trips . It can be avoided by flying high and behind instead of same height or lower.

[DarkHelmet]

Prop wash/Wake Turbulence occurs the moment an aircraft gets airborne and starts to fly.

See http://en.wikipedia.org/wiki/Wake_turbulence

It always washes down behind the aircraft in front of you. Key is, on take-off, when in group, have the heaviest aerie in front and the lighter ones behind. The heavier aerie will have a longer roll and the lighter ones can thus get airborne over a shorter distance behind it. The vortices only start once airborne and thus you will take off over them as a result. If the runway is too short, wait it out! 2 minutes should be safe.

On landing in close formation it is the opposite, the one that can put down closest to the numbers goes first (weight does not play a role here, just your touchdown point). Aerie 1 has to touch as close to the numbers and aerie 2 basically has to fly 'over' the path aerie 1 flew and touch down a bit deeper to miss the wake turbulance. Once again, if the runway is short stay in the air a bit longer

That is the theory

I flew into Big D's propwash just after Christmas on an approach at Aviators Paradise, Newspaper headlines flashed through my head at that moment - it is really something to be carefull of and you do not understand how dangerous it can be until you actually experience it.

When flying behind someone always stay at least the same level, but it is better to be higher than them.

Be wary of your own propwash too. If you do a 360 turn you can fly into your own propwash!

If I had to ask Thunderboy to print me a T-shirt for each of my propwash experiences he could retire, none of em were nice and the first thought to cross your mind is where am I aiming to ditch, if there is no time to aim the newspapers headlines flash in front of me!

PS: Please correct me anywhere if I am wrong!

[Biggles]

What we are really talking about is a combination of prop-wash and wake turbulence. Wake turbulence is a bigger problem that prop-wash.

I was flying to Malmesburg with another trike. I was wing-man but the other trike kept drifting in behind me. I remember looking back to see where he was just as he hit my wake... it looks quite spectacular from a stable vantage point

I believe the safest place is slightly above and to the right when in formation?

Am I correct in saying that it is only a problem after rotation on take-off and until all wheels are on the ground for landing. Wake turbulence is highest at high angles of attack (take-off and landing).

What I do is watch the flight path of the aircraft landing ahead of me and select an approach that either has me rounding out after the point where they touched down and a shallow approach, or going in steep underneath their flight path.

In my experience Gyros create quite alot of turbulence.
And it hangs around for quite a while on calm days. I felt wake turbulence from a gyro after it had vacated the runway. (and we all know how long that takes them;))