[jhb_airlines] Re: Off For A Few Days

  • From: "Fred Stopforth" <fredstopforth@xxxxxxxxxxxxxx>
  • To: <jhb_airlines@xxxxxxxxxxxxx>
  • Date: Tue, 29 Jul 2008 17:28:12 +0100

Best Wishes. Fred PS only 5 more working days left to do in last week of Aug. Oh oh oh what will I do? Nah no problem loads to do. ----- Original Message ----- From: "F FISHER" <ffisher991@xxxxxxxxxxxxxx>

To: <jhb_airlines@xxxxxxxxxxxxx>
Sent: Tuesday, July 29, 2008 2:05 PM
Subject: [jhb_airlines] Re: Off For A Few Days


Must be catching, I am off early Thursday, for 10 days, will not be available for this and next Wednesday.

Frank F
----- Original Message ----- From: "Fred Stopforth" <fredstopforth@xxxxxxxxxxxxxx>
To: <jhb_airlines@xxxxxxxxxxxxx>
Sent: Tuesday, July 29, 2008 1:04 PM
Subject: [jhb_airlines] Re: Off For A Few Days


Bones+ Crew, I'm taking leave as from 30th July to 5th Aug.Going to Madrid with Easyjet.So will catch up when I get back. Hasta la vista. Fred ----- Original Message ----- From: "Bones" <bones@xxxxxxx>
To: <jhb_airlines@xxxxxxxxxxxxx>
Sent: Monday, July 28, 2008 8:19 PM
Subject: [jhb_airlines] Re: Start Up Solution Needed


The Comanche isn't for beginners but is an ideal step up aircraft. It's not the VP prop or landing gear that is the problem - most pilots can move on to these without too much trouble - but the wing design and the handling this
requires.

You don't get anything for nothing and that is particularly true of
aviation. To increase the speed of an aircraft you can either increase power or make the aircraft more streamlined. The Drag rule is the bummer for the
first as it increases as the square of the speed and so power needs
increasing to match - four times the power to double the speed.. The second requires more thought about design, cutting out unwanted drag and generally
needs more time and more complex construction techniques.

The original PA24 had the same 180hp engine as the Cherokee so its 150kt
cruise was all down to its sleeker design. The fuselage was certainly less chunky (inside was less roomy than the Cherokee) but the biggest improvement was the choice of a laminar flow wing - as used on later Spitfire variants and the Tempest. I won't go into all the theory about laminar flow here but its characteristics requires some understanding by the pilot otherwise he'll
be dead very quickly.

The Cherokee has a rather fat wing. This is good for a novice as fat wings
are draggy but safe - ideal for training. You don't need to go fast in a
trainer so the drag isn't an issue but it's useful in other areas - it makes the aircraft slow down quicker. This makes it easy to slow down from cruise speed to approach speed and it also allows pilots to get height off easily if high on final (without having the speed get out of hand). The fat wing also has very benign stall characteristics and the NACA 23012 aerofoil on the PA28 provides a nice gentle stall with plenty of pre stall warning. In other words the wing is safe and cuddly and comfortable and it won't get you into serious trouble unless you really abuse it. The downside is that it can create a false impression that all aircraft handle in the same way and it
can be a shock when you find they don't.

The laminar flow wing of the PA24 requires much more care and thought - and
some homework on aerodynamics. Those of you who have flown the FS Siai
Marchetti SF260 will probably understand what I am going to say now because
Real Air have produced an almost perfect flight model for a laminar flow
wing with this aircraft - and it shows.

Being a thinner wing laminar flow produces less lift. It also creates less drag so is ideal for faster aircraft. Less lift means longer take off and landing distances unless fitted with a complex flap system to compensate. Less drag sounds a good idea but pilots used to a draggy aircraft can get caught out by this. A sleek design doesn't slow down easily. Not only that but it's more slippy too because if you lower the nose to descend it starts
speeding up again. The golden rule of these aircraft is that you need to
plan ahead for descent because if you are both too high and too fast you've
already got into an unrecoverable situation. With a fast wing you can
descend OR you can slow down - but you CANNOT do both at the same time. It is these aircraft that begin your education in proper aircraft management.

The laminar wing also has vices. Being thinner it creates less lift than a
fat wing and the wing loading is greater (assuming the same wing area).
Stalling speed is higher but the stall itself is sharper and more abrupt
with none of the benign behaviour of the fat wing. A fat wing will normally stall at a 15 degree AoA but the laminar wing is less than this owing to the reduces curvature of the top wing surface. A sudden pull on the elevators
can stall a laminar flow wing quite quickly (as SF260 flyers may have
found). It therefore needs much more careful and considerate handling by the
pilot.

Having all that under your belt I can say that the PA24 was a delight to fly
and it was much nicer cruising along at 150kts instead of 110kts in a
Cherokee. Controls were crisper too and it handled more like a pocket
fighter - as long as you gave it due respect. Lovely aircraft.

bones
bones@xxxxxxx
http://woodair.net


-----Original Message-----
From: jhb_airlines-bounce@xxxxxxxxxxxxx
[mailto:jhb_airlines-bounce@xxxxxxxxxxxxx] On Behalf Of Peter Dodds
Sent: 28 July 2008 11:48
To: jhb_airlines@xxxxxxxxxxxxx
Cc: pdodds@xxxxxxxxxxxxx
Subject: [jhb_airlines] Re: Start Up Solution Needed

A member of Cix flies a Single Comanche which belongs to his Dad. He says it's only drawback is that it needs longish runways to land and take off.
750 metres is "comfortable".  He went to Eshott last Sunday (650m) which
he described as " a bit interesting with a touchdown speed of about 100
knots in the very brisk wind we had.". Incidentally, and not relevant, He
flies out of Bournemoouth and he and his Dad always take their aircraft
(I think they own 3!!) over to Jersey to refuel. Before going up to
Eshott, he had already "popped over to Jersey" for fuel. How the other
half live, eh?

Peter



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