Cape Town Flying Club News 5 April
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Courses

Night Circuits at FAWC

FARS breakfast
Aircraft Accidents and Incidents
General
- TAE leaving us
- Bar to be open

- Red Bull Air Race
Traps for unwary pilots: ground effect

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Dates to Diarise

10 April : Meteorology course

14 April: Night ciruits at FAWC

21 April: FARS breakfast

27-30 April: De Aar fly in

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Courses

10 April
Meteorology,lectured by Peter Erasmus

Call the club (021-934 0257) to book. Members are reminded that you can do the course as a "refresher" at half price.

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Night Circuits At FAWC 14 April --> Linda Hodgkinson

Things are on track for our planned flight to Nadini and then on to FAWC on 14 April. Many of the aircraft have already been booked but if you hurry you may be lucky enough to get one. If you have missed out, let Linda know if you would like to share a flight. If you were one of the lucky ones to get a plane and have a spare seat, also let Linda know and she will put you in contact with one another.

Details regarding the catering arrangements (the plan is for everyone to bring their own, but there will be economies of scale we can avail ourselves of, I’m sure) will be discussed closer to the time as will the time and place for the pilot briefing before departure.

For those who missed last week’s newsletter, here is the airfield info again:

Airfield info according to Airfields Directory:

FAWC: S33 40 E019 25.00

Runway: 15/33 1600m.

Remember to stay on the dam side of the airfield at all times, i.e. right hand circuit if 15 is in use – pilot briefing to take place before the event.

Fuel: to be confirmed closer to the time

Landing fees: waived (thanks Dick)

Nadini: S33 27 39.6 E019 51 30.0

Runway: 11/29 1600m gravel. Extra care should be taken with the a/c during run-up – also to be discussed at pilot briefing.

Fuel: no

Landing fees: none

You are also welcome to bring the family up by car and spend the day with us if you don’t want to fly.

SEE YOU THERE!

If you would like to stay in a guesthouse, and are worried about transport to and from FAWC, contact Linda.

Contact: Linda Hodgkinson

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Breakfast at FARS Saturday 21 April --> Robertson Flying Club

Robertson Flying Club is hosting their annual fly-in breakfast on the 21st of April from 9:00 to 11:00 at R50 per person.

Come and enjoy a morning (or day) in the valley of wine and roses. Bring a tent and sleep over in the clubhouse lawn. Hot shower and toilet facilities available at the clubhouse.

Airfield Info:

FARS: Licenced
Altitude: 640 feet
Runways: 10/28 1600m x 15m tar
Frequency: 124.8
Fuel: Avgas available

Contact: Alwyn 083 270 5888
Last year we had better weather than forecast. Phone if you are uncertain of local weather conditions

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Incidents and Accidents 11 of 20: Fun with pictures --> Danny Buitendag

The new circus trapeze act was a great hit

( GP: The aircraft in the picture, a Cessna 150 registration N39AA, was landing behind a Beech D-18 when it encountered wake turbulence which caused the pilot to lose control. The pilot ended up flying 90 degrees to the 10 000' runway and into the power lines. The pilot was trapped in the aircraft for four (or three, depending on source, see reports below) hours before fire crews were able to get him down uninjured.

NTSB report: http://www.ntsb.gov/ntsb/brief2.asp?ev_id=20001211X09955&ntsbno=SEA98IA060&akey=1
From the Rescue Crew's perspective (with pics): http://www.ladder54.com/Photosplane.htm
)

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General

TAE

Due to circumstances beyond the club's control, TAE will no longer be available to the flying club from the 16th of April. All flying until then will continune to be dual only. All members who have booked after the 16th must please understand that the cancellation of flights is unavoidable. For those that want to fly 172's, the avgas JDN should be returning sometime.

Bar Open

The bar will be open on the weekends (including Friday night), and our DSTV is up and running, so pop in for a drink (after the flight) and watch our guys thrash the opposition in the cricket!

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Red Bull Air Race --> Schalk Burger

The 2007 World series takes off in Abu Dahbi on the 5th and 6 of April. 14 Pilots in 12 international races, so expect some awesome viewing.

http://www.redbullairrace.com

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Traps for unwary pilots: ground effect --> G Pinnock

We've all used ground effect to help us with short field take offs, so how could this be called a trap for an unwary pilot? Well, like most good things, it can be abused, with disastrous results.

Ground effect may allow an overloaded plane to leave the runway while the aircraft desperately tries to get airborne, only to find itself sinking back to the ground with a nice smooth runway behind, and zero options ahead. Or picture the poor student who tries hard to make the plane land gracefully and finds that the plane floats down the runway when it was expected to land (which can often cause the hapless student to force the plane down... generally resulting in the plane doing a plausible imitation of a kangaroo).

The superpowers understood ground effect very well; in fact, they even created aircraft to operate only in ground effect. Even something with a brain as small as a bird utilises the "ground effect" to minimize effort (which is why birds often fly in a V-formation).

So why does flying close to the ground (or in formation) allow a plane to fly before it should? The brief answer is a reduction in drag. To understand why, we need to examine a few basic principles.

We all know there are pressure differentials around the wing (aerofoil) and that this creates the conditions neccessary for lift. We also know that lift produced by the aerofoil is perpendicular to the relative airflow. In normal flight (i.e. away from the ground), the high pressure air below the wings “curls” over the wingtip to the top of the wing and disrupts the low pressure, causing drag and forming wingtip vortices. (As an aside, many aircraft, such as the 747-400, have winglets fitted to hinder the “curling” of the air).










Additional drag is the created when the vortices influence the airflow around the wing, creating a slight upwash in front of the wing, and a downwash behind the wing.











This downwash and upwash alters the relative airflow, which then inclines the lift vector back slightly. This vector can then be broken into a vertical component (lift) and a horizontal component (drag). An increase in angle of attack leads to greater pressure differentials over the wing, leading to stronger vortices, which leads to more drag, which is why induced drag decreases with speed (the angle of attack is reduced to maintain level flight at higher speeds).













Which all brings us back to the ground. Close to the ground, the creation of vortices is greatly reduced which leads to a decrease in induced drag. (I say close to the ground, because we don't generally fly like birds in formation).












The decrease in the downwash and drag are two things that should be understood by the pilot. Elevators can be affected by the downwash of the wing (except obviously in the Tomahawk), which is why the elevator can lose effectiveness while in ground effect. Pilots who haul their aircraft off the ground and stagger into the air may suddenly find the elevator increase in effectiveness once out of ground effect, which would immediately put the aircraft into an extreme nose-up attitude, with the resultant danger of a stall. (As an aside, the elevator effectiveness while in ground effect plays a huge role in determining the CG fore and aft limits.)

So how do we make use of this phenomenon to our advantage?

If you are doing a short field take off, remember to accelerate to a safe climbing speed, which will allow the aeroplane to fly once you lose the helping hand offered by ground effect. If you don't, bear in mind that the sudden increase in drag can cause your power required to exceed the power available, which leaves only one option - going down. This is something to remember especially when flying KSS or PMY - prematurely retracting the gear and trying to climb out of ground effect can dent both your pride and the aircraft.

On landing, be careful of any excess speed. When an instructor wants 70 kts, they mean 70 kts for a very good reason. The sudden decrease in drag means that any excess speed can cause the aeroplane to float happily down the runway for a long time. A quick calculation reveals that at 70 kts, every second in the air uses (read ‘wastes’) 35m of runway. Obviously this increases as the speed increases (80 kts = 40m/s), which can eat up your short landing field very quickly. Besides the float, a pilot may be tempted to plant the aeroplane down, with the resulting aforementioned kangaroo imitations (and possible damage to the aircraft).

Ground effect can lend a helping hand if you are expecting it. Just use it wisely.

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