Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)

[Peter Gunn]

At 6' 2.5" I'd like to know how's the weather down there?

As one who stands about two turds and a half above ground fully stretched, I strongly protest against this recent fixation on height, first disguised as ceiling of aircraft but now blatantly heightist and clearly demeaning of us who are vertically challenged.

Anybody sharing in my experience of being relegated a status as below average, is recommended to join us in the movement for equal heights.

 

[XBe02Drvr]

As one who stands about two turds and a half above ground fully stretched, I strongly protest against this recent fixation on height, first disguised as ceiling of aircraft but now blatantly heightist and clearly demeaning of us who are vertically challenged.
Anybody sharing in my experience of being relegated a status as below average, is recommended to join us in the movement for equal heights.

Consider yourself fortunate you're not banging your head on door frames and bending your knees backward to get in and out of MGBs, Triumph Spitfires, and J3 Cubs!
Get yourself a pair of these:

And quityerbellyachin!

 

[pbehn]

Yes, the first production Spit I weighted full loaded 5,819 lbs. Did you notice that British used 200 lbs for pilot and parachute? According to you that is too much, or do you believe British were better fed than US citizens in 1939 - 41? BTW, what is your source for your claim "Average American man in the Army in WWII was 5'8" and weighed 140lbs" in your message #2,429? The last Spit Mk which saw service during the WWII was F Mk 21, Typical service weight (without external load) 9,420 lbs, max with 90 gal blister tank, 10,202 lbs.

The first production Spitfires changed weight as they were being produced and after. The gun heating system was introduced during production. They then replaced the wooden prop with variable pitch and then CS props. They fitted armour initially to the bulkhead and then behind the pilot. It is all completely academic though. The exhaust heating system from fish tail exhausts increased thrust and so top speed. The variable pitch and VP and CS props + 100 octane fuel completely transformed performance giving a much higher ceiling, top speed plus rate of climb with 30% less distance needed for take off run.

 

[GrauGeist]

Wonder what the weight difference was between the original two-bladed prop and it's replacement?

 

[pbehn]

Wonder what the weight difference was between the original two-bladed prop and it's replacement?

From Wiki The early Mk Is were powered by the 1,030 hp (768 kW) Merlin Mk II engine driving an Aero-Products "Watts" 10 ft 8 in (3.3 m) diameter two-blade wooden fixed-pitch propeller, weighing 83 lb (38 kg). From the 78th production airframe, the Aero Products propeller was replaced by a 350 lb (183 kg) de Havilland 9 ft 8 in (2.97 m) diameter, three-bladed, two-position, metal propeller, which greatly improved take-off performance, maximum speed and the service ceiling.

I make that +267Lb

Then "In June 1940 de Havilland began manufacturing a kit to convert their two pitch propeller unit to a constant speed propeller. Although this propeller was a great deal heavier than the earlier types (500 lb (227 kg) compared with 350 lb (183 kg)) it provided another substantial improvement in take-off distance and climb rate. "

I make that +417 Lb compared to the Watts two blade prop.

Also "Starting in September 1940, IFF equipment was installed. This weighed about 40 lb (18 kg) and could be identified by wire aerials strung between the tailplane tips and rear fuselage. "

 

[GrauGeist]

So that's a considerable jump in weight, especially at the front of the airframe - I wonder what adjustments were made to preserve CoG.

 

[Juha3]

The first production Spitfires changed weight as they were being produced and after. The gun heating system was introduced during production. They then replaced the wooden prop with variable pitch and then CS props. They fitted armour initially to the bulkhead and then behind the pilot. It is all completely academic though. The exhaust heating system from fish tail exhausts increased thrust and so top speed. The variable pitch and VP and CS props + 100 octane fuel completely transformed performance giving a much higher ceiling, top speed plus rate of climb with 30% less distance needed for take off run.

5,819 lbs was the fully loaded weight of K 9787, the first production Spitfire, in August 1938. Source Price, The Spitfire Story (1995) p.81

 

[pbehn]

So that's a considerable jump in weight, especially at the front of the airframe - I wonder what adjustments were made to preserve CoG.

From what Ive read here the CoG moving forward is less serious than moving back, and they were putting stuff like IFF and radios etc behind the CoL.

I read in a book years ago that the boffins were concerned about putting armour behind the pilots in Hurricanes, the pilots in France werent, they made and put in their own.

 

[pbehn]

5,819 lbs was the fully loaded weight of K 9787, the first production Spitfire, in August 1938. Source Price, The Spitfire Story (1995) p.81

I am not disagreeing, but as per my other post if it remained in service it will have been fitted with other stuff like props and armour IFF etc. The gun heating system was installed on the 61st Spitfire. They are all called Mk Is even when they started fitting cannon to them a cannon armed Mk I became a Mk IB and all those with 8 Mgs retrospectively were MkIAs.

 

[MikeMeech]

From what Ive read here the CoG moving forward is less serious than moving back, and they were putting stuff like IFF and radios etc behind the CoL.

I read in a book years ago that the boffins were concerned about putting armour behind the pilots in Hurricanes, the pilots in France werent, they made and put in their own.

Hi
The book 'Knights of the Skies - Armour protection for the British fighting aeroplanes' by Michael C Fox, appears to differ in opinion to your statement, pages 218-220 has the following for example:

Mike

 

[pbehn]

Hi
The book 'Knights of the Skies - Armour protection for the British fighting aeroplanes' by Michael C Fox, appears to differ in opinion to your statement, pages 218-220 has the following for example:
View attachment 632000
View attachment 632001
View attachment 632002

Mike

Thanks, it was something to do with the admin or certification of what is described being flight tested. It may have been the plan to switch all Hurricanes to Rotol props before going to France but things didnt go to plan in this is a picture of Cobber Kain in France with his Hurricane carrying a Watts two blade prop. 'Cobber' Kain - first RAF Hurricane Ace, first RAF air ace of the WWII, and first to receive the Distinguished Flying Cross - The Aviation Geek Club.

My point was about people being much more concerned about the CoG going aft than fore

 

[SaparotRob]

Hi
The book 'Knights of the Skies - Armour protection for the British fighting aeroplanes' by Michael C Fox, appears to differ in opinion to your statement, pages 218-220 has the following for example:
View attachment 632000
View attachment 632001
View attachment 632002

Mike

Thanks for that link. I enjoyed reading it.

 

[Glider]

So that's a considerable jump in weight, especially at the front of the airframe - I wonder what adjustments were made to preserve CoG.

I only know a little on this but the weight gain did have to be carefully managed. The very first Spitfires with the initial two bladed prop were actually tail heavy and weights were added in the nose.
As has been mentioned this very quickly changed and they ended up with weights in the tail.

I said it had to be carefully managed in particular the Spit V. These were in service for a long time and a lot of extra kit was installed during this period. I read one book where the writer was promoted and transferred to a different station still on Spit V and the planes handling was dreadful. He looked into it finding that extra equipment had been installed but not as the instructions and this had played havoc with the Cog and handling.
He grounded the unit until it had all been removed and reinstalled correctly and the problem went away.

If anyone thinks this couldn't happen in more modern times I was talking to an ex Canadian engineer and he described an CF-5 which came in for a major update before being transferred. They found to their horror that over time equipment had been upgraded and replaced but not all the old cabling had been removed. They took approx 150Ib of cabling out that wasn't attached to anything.

 

[buffnut453]

I only know a little on this but the weight gain did have to be carefully managed. The very first Spitfires with the initial two bladed prop were actually tail heavy and weights were added in the nose.
As has been mentioned this very quickly changed and they ended up with weights in the tail.

I said it had to be carefully managed in particular the Spit V. These were in service for a long time and a lot of extra kit was installed during this period. I read one book where the writer was promoted and transferred to a different station still on Spit V and the planes handling was dreadful. He looked into it finding that extra equipment had been installed but not as the instructions and this had played havoc with the Cog and handling.
He grounded the unit until it had all been removed and reinstalled correctly and the problem went away.

If anyone thinks this couldn't happen in more modern times I was talking to an ex Canadian engineer and he described an CF-5 which came in for a major update before being transferred. They found to their horror that over time equipment had been upgraded and replaced but not all the old cabling had been removed. They took approx 150Ib of cabling out that wasn't attached to anything.

But surely all they needed to do was move the radio and IFF to fix things, right? Simples!

 

[pbehn]

The very first Spitfires with the initial two bladed prop were actually tail heavy and weights were added in the nose.
As has been mentioned this very quickly changed and they ended up with weights in the tail.

It must have been well understood that a heavier prop was coming, that was the reason ROTOL was formed in 1937, and the Merlin III with a drive shaft that could take both ROTOL and de Havilland props started to be delivered from 1 July 1938.

 

[FLYBOYJ]

I only know a little on this but the weight gain did have to be carefully managed. The very first Spitfires with the initial two bladed prop were actually tail heavy and weights were added in the nose.
As has been mentioned this very quickly changed and they ended up with weights in the tail.

I said it had to be carefully managed in particular the Spit V. These were in service for a long time and a lot of extra kit was installed during this period. I read one book where the writer was promoted and transferred to a different station still on Spit V and the planes handling was dreadful. He looked into it finding that extra equipment had been installed but not as the instructions and this had played havoc with the Cog and handling.
He grounded the unit until it had all been removed and reinstalled correctly and the problem went away.

If anyone thinks this couldn't happen in more modern times I was talking to an ex Canadian engineer and he described an CF-5 which came in for a major update before being transferred. They found to their horror that over time equipment had been upgraded and replaced but not all the old cabling had been removed. They took approx 150Ib of cabling out that wasn't attached to anything.

This happens all the time in the military and civilian world and I'd bet dollars to donuts it occurred during WW2

 

[GrauGeist]

While not a weight issue, in the past, while working on older fire engines in extended service, I encountered considerable amounts of cabling left behind during equipment upgrades.
In some cases, still live.
It was frustrating, especially when trying to trouble-shoot problems.

 

[nuuumannn]

For once can you just admit you were wrong?

"Never!"

Attributed to Winston Churchill in 1940 and P-39 Expert in 2021...

 

[nuuumannn]

Let's put it this way, if I were a mod I'd shut this down. It's pointless. You guys are tying yourselves in knots to prove this guy wrong and he's not listening.

 

[GrauGeist]

Let's put it this way, if I were a mod I'd shut this down. It's pointless. You guys are tying yourselves in knots to prove this guy wrong and he's not listening.

It would be like a game of "whack-a-mole", though, because one P-39 thread gets closed and then another P-39 thread gets revived and hijacked.