I've never worked on the Spitfire but I suspect you're correct.

Aye it is the cooling port for the generator, I've got a gorgeous picture of a Packard Merlin 266 and you can see the generator clearly and it measures up to the cowling perfectly

I can't remember if there is, but the manual is an invaluable tool for Spitfire lovers
Some amazing and wonderful technical details 8)

The drag isn't that bad as it is the area of the prop-wash, so it gave sufficient cooling without being a burden like the Vokes filter which cost performance in a very noticable way.

In response to your first question about the Spit cowl.....I'm thinking your talking about this area.....


And in response to your question on flaps, here is how I see it.........
When you deploy flaps on an aircraft, an initial pitch-up should be noticed as you begin to change the airfoil section to one of slight undercamber (Glider-style with more lift but also more drag) but as this increased drag starts to diminish the airspeed and the flap angle increases, the lift component is decreased and the nose should drop due to insufficient airspeed at the new angle of attack........nose down will prevent further decay in airspeed, which would eventually cause a stall...

Rifleman,

Yes, your very clear photo identifies the cowling concerned exactly. It must be an inlet for cooling air for the generator, as Ozzy says, it is directly in line with the generator. However I have yet to find a specific written reference to it anywhere in my literature or on the net.

Your aerodynamic description is also correct.
The Spitfire V pilot's notes under "10.  General Flying" state :-  "Change of trim"....."Undercarriage down--Nose down"...."Flaps- Nose Down".
What the Pilot's Notes do not say is how much change of trim.
I am trying to gather some typical values for this so that I can accurately model an air file for the Spitfire. Most of the air files currently available either get it completely wrong by giving none or a nose up change of trim or give a nose down reaction that seems excessive ( especially for the undercarriage , which I suspect had comparitively little effect).

I am hoping that some Spitfire pilot out there can tell us !

I am going to see the Shuttleworth Collection fly at Old Warden tomorrow and it includes a Spit MkVc. In the unlikely event that I can get near the pilot I'll ask him.

Thanks for your comments.

Springer, I thought you were indicating that intake so I brought it to the front since I could. I took that shot a few weeks back in the Seattle Museum of Flight on the Mothers day weekend.........cheers......... 8)

On the flap issue..........
I do concur with Doug on his assessment of flap effect on pitch, but my explanation was not that of an instant "snap" flap.....it was more of what happens through the gradual application of flaps as they progress from no flap to full flap position........sorry for not clarifying this at the time........

Yes I think that on all marks of Spit , the flaps were LOWERED by the use of compressed air from the same source as for the brakes. I don't know how long it takes , but it can only be a matter of a couple of seconds. ( I'll try to time it,  next time I see a Spit on approach, but it will probably be too distant).

The flaps are RAISED by releasing the air to atmosphere via the flap control valve and the flaps are then raised by a spring box attached to each flap, assisted of course by the slipstream if the a/c is in flight or  ground running .This spring return, I would have thought, would be fairly quick.

The undercarriage is raised and lowered by a hydraulic system and speed of operation is therefore dependant upon the speed of the engine driven ( or manual for early a/c ) pump. Therefore for take off, speed of raising is fairly quick for non manual systems , but can be quite slow for lowering if the pilot leaves dropping  the chassis until  late in the approach with the  consequent low engine speed. In an emergency the undercarriage could be lowered ( but not raised) by discharging the contents of a Carbon Dioxide bottle into the downside of the operating ram. In any case I don't think that the lowereing undercarriage would give the initial nose lift that lowering flaps might.

As the flaps are lowered they should give a brief second or two of lift whilst getting to the down position, then they really are airbrakes!
Another thing to remember with the U/C down is overheating as the U/C disrupts the airflow to the radiator(s)/oil-cooler, so you can only have them down for a short time before your Merlin starts cooking

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I think this is only while they are in transit. If they jam half-way, as they often did, you have problems.

A Shuttleworth Collection pilot , Neil Williams , in describing his experience of flying the collection's MkVc says that with the single radiator models , even taxiing slowly causes coolant temprature to rise alarmingly as the starboard undercarriage leg is masking the radiator .

At Old Warden yesterday , I had a chat with a pilot who flys their Spitfire VC ( now fitted with standard wing tips as opposed to its original clipped wings ).

He confirmed that lowering the flaps causes a nose down change of pitch. He was unable to say exactly how much as he automatically holds it on the stick whilst trimming out. He felt that lowering the undercarriage caused very little if any change of pitch.

On speed of deployment, he said that if tested on the ground the flaps would deploy "bang instantly" under pneumatic pressure, but in the air when acting against the airflow they would take "a second or two". The flaps powered by their return springs raised equally quickly.

A mechanic , who works on the Spitfire, confirmed that the cowling detail shown in Rifleman's photo was indeed to direct airflow over the Merlin's generator. He pointed out that the Collection's Sea Hurricane also had a similar if less obvious air pick up on the port cowling.

Another pilot who had flown both types pointed out that the Hurricane was very much less prone to overheating than the similarly engined Spitfire , due to it's larger centrally mounted radiator which is not masked by either flaps or undercarriage.

Another interesting aspect of seeing these two birds fly together at close quarters was the noticable difference in their sounds ( even though they are powered by similar engines and props. The Spitfire has a distinctive "whistling sound" in flight that can be heard above the general roar of the Merlin . I understand that this "whistling" is caused by the air passing through the Morris type radiator. Apparantly this sound was not present with the early Serck type radiators.

The flying aircraft housed at Old Warden range from a 1910 Bristol  Boxkite to a 1946 Chipmunk. The staff are friendly and informative and it's a beautiful location. I recommend a visit.
http://www.shuttleworth.org/shuttleworth/index.htm

Great photos Hagar...made up for my rather disapointing results.

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LOL I was going to ask you that. I'm terrible with names. Chap with receding hair - don't tell him I said that. Name began with an M - could it have been Rob Millinship? He was standing in front of the Gladiator when I grabbed him for a chat. One of the regular pilots although he told me he hasn't flown the Spitfire - yet.

Charlie,

The Shuttleworth pilot who I spoke to was in his mid forties with receding hair, about 5' 9". I didn't get the opportunity to ask his name as he was quite busy on the flightline in discussion with mechanics.

He confirmed that he flew the Spitfire , but was not the chap who flew it later in the afternoon display. That pilot was  a large  military looking guy in his ( late?) fifties with shortish grey hair and a very ruddy complexion.

All the staff, from shop staff to mechanics and pilots were extremely helpfull and friendly. This all contibuted to a marvellous day. It  was my first visit to Old Warden  ( apart from on the Sim. ) and even though it was a 400 mile round trip for me I will certainly be back.