P-51 fuselage fuel tank (3 Viewers)

[z42]

There was a firewall between the pilot and the tanks in front of him. Sitting on a unprotected tank would not be popular

In any case having big fuel tanks just ahead of the pilot seems extra dangerous, as the slipstream would push flames and burning fuel right into the cockpit.

Though apparently we have this to thank for advances in plastic surgery in the early WWII years. But what a ghastly price..

IMHO, would have been better to put the cockpit as far forward as possible, and instead put fuel below/behind the pilot, or in the wings. Better forward visibility as well. Oh well.

 

[Engineman]

In any case having big fuel tanks just ahead of the pilot seems extra dangerous, as the slipstream would push flames and burning fuel right into the cockpit.

Though apparently we have this to thank for advances in plastic surgery in the early WWII years. But what a ghastly price..

IMHO, would have been better to put the cockpit as far forward as possible, and instead put fuel below/behind the pilot, or in the wings. Better forward visibility as well. Oh well.

In the case of the early Spitfire, the tankage was as simple as possible, just behind the engine as close as possible to the C of G and effectively gravity fed to the engine fuel pump.

Eng

 

[drgondog]

Late war the RAAF removed the IFF from P-51D&K aircraft when the rear fuselage tank was used. By that time the allies had air superiority in the SWPA.

This is a great find. The US operated P-51D/K placed IFF fwd of firewall and the carb return line always went to left main.

Many RAF Mustang III were delivered without 85gal tank but I was unclear regarding P-51D/K. Do you know if RAAF received any MK IV or IVa directly from US, or purchased by RAF and then allocated?

 

[EwenS]

This is a great find. The US operated P-51D/K placed IFF fwd of firewall and the carb return line always went to left main.

Many RAF Mustang III were delivered without 85gal tank but I was unclear regarding P-51D/K. Do you know if RAAF received any MK IV or IVa directly from US, or purchased by RAF and then allocated?

Mustangs used by 3 RAAF and 450 squadrons in Italy came from RAF stocks.

Those that started equipping RAAF squadrons in Australia from mid-1945 were Lend Lease allocations to Australia.

Details of all Aussie Mustangs here

ADF Serials - Mustang

 

[MIflyer]

The US operated P-51D/K placed IFF fwd of firewall

Really? I would not have thought there would be enough room.

The US developed a new, UHF, much more sophisticated IFF, the BC-645, that had all kinds of features including the ability of aircraft to interrogate each other. But the British refused to change and you can't very well have two different IFF systems. As a result the BC-645 became a common surplus item offered to radio amateurs for about the next 40 years.

 

[Engineman]

Really? I would not have thought there would be enough room.

The US developed a new, UHF, much more sophisticated IFF, the BC-645, that had all kinds of features including the ability of aircraft to interrogate each other. But the British refused to change and you can't very well have two different IFF systems. As a result the BC-645 became a common surplus item offered to radio amateurs for about the next 40 years.

View attachment 788739

Good value! Unfortunately, I am saving for a $1,000 P51-D Mustang!

Eng

 

[MIflyer]

Good value! Unfortunately, I am saving for a $1,000 P51-D Mustang!

A friend of mine said a guy he knew was driving through the midwest in the 60's and passed a rural school with a P-51 in the playground. He stopped, went to see the principle, and offered to take that beat up eyesore off his hands. The principle agreed. The canopy was smashed and he found a surplus store selling new unused canopies for use as fish tanks.

There was a school on Pacific Coast Highway just north of Santa Barbara. It had an F-86A in the school yard for the kids to play on. The CAANG came and got the F-86A for use in a museum and replaced it with an F-86F. While I lived out there the school was taken over by an oil company and replaced by new prefab buildings a few miles down the road; they were much nicer but not nearly as pretty. The CAANG came and got the F-86F for use in a museum.

 

[Zipper730]

Then you are wrong.

Well, I obviously know that. It was just an instinctive guess.

Regardless, what caused the control-reversal?

 

[Engineman]

Well, I obviously know that. It was just an instinctive guess.

Regardless, what caused the control-reversal?

In this case it is not "control reversal", what the report says is that "control loads rapidly reverse". What this means is that instead of requiring increasing stick load per G, the stick load per G decreases. This is a difficult response to handle, where normally, stick loads increase per G. This effect varies in different aircraft and with increasing aft Cof G.

Eng

 

[MiTasol]

This is a great find. The US operated P-51D/K placed IFF fwd of firewall and the carb return line always went to left main.

Many RAF Mustang III were delivered without 85gal tank but I was unclear regarding P-51D/K. Do you know if RAAF received any MK IV or IVa directly from US, or purchased by RAF and then allocated?

I am not into RAAF P-51 history but this site is pretty good. Has some terrible errors (due mainly to the quality of the records they are working from) but I still rate it highly.

Home

adf-serials.com.au

The RAAF P-51 individual aircraft history is here and includes a page on RAF serials.

ADF Serials - Mustang

 

[Zipper730]

In this case it is not "control reversal", what the report says is that "control loads rapidly reverse". What this means is that instead of requiring increasing stick load per G, the stick load per G decreases. This is a difficult response to handle, where normally, stick loads increase per G. This effect varies in different aircraft and with increasing aft Cof G.

So, the airplane becomes very twitchy on pitch?

 

[MIflyer]

The P-51 was equipped with "bob weights" that were designed to counter the tendency to tighten up when the elevator was used with aft CG.

 

[PAT303]

In this case it is not "control reversal", what the report says is that "control loads rapidly reverse". What this means is that instead of requiring increasing stick load per G, the stick load per G decreases. This is a difficult response to handle, where normally, stick loads increase per G. This effect varies in different aircraft and with increasing aft Cof G.

From what I understand both the P51 and Spit tightened their turns with full rear tanks so they needed less force on the stick, is that correct?.

 

[Engineman]

So, the airplane becomes very twitchy on pitch?

That depends what "twitchy" is mean't to be? You have an original fairly authoritative report of handling changes with a specific modification, I would work with that.

Eng

 

[Engineman]

From what I understand both the P51 and Spit tightened their turns with full rear tanks so they needed less force on the stick, is that correct?.

As I just wrote to Zipper, you need to find and read the flight test reports of specific aircraft to know.
Very generally, this situation being discussed is a modification that moves the aircrafts C of G back beyond the normal limit and increases the total weight. So, in times of need, such changes might be allowed if the extra problems can be assessed and mitigated.

Eng

 

[drgondog]

In this case it is not "control reversal", what the report says is that "control loads rapidly reverse". What this means is that instead of requiring increasing stick load per G, the stick load per G decreases. This is a difficult response to handle, where normally, stick loads increase per G. This effect varies in different aircraft and with increasing aft Cof G.

Eng

Actually at stick force per G reaches zero, there is a control reversal where fwd pressure on stick is required to maintain the turn - which is why bob weights were added to the 85gal equipped Mustangs. The P-51H did not have that issue.

 

[Engineman]

Actually at stick force per G reaches zero, there is a control reversal where fwd pressure on stick is required to maintain the turn - which is why bob weights were added to the 85gal equipped Mustangs. The P-51H did not have that issue.

You might have a different report that describes the response in this specific case differently to the one in this thread?
I think you will find that the terms here should be very specific. In this case in the report, and what you describe, is not control reversal, it is changes in control loading, the aircraft still responds in the same sense to stick movement, but the stick load per G reduces with stick movement when the Cof G is too far aft and this is a difficult handling trait.
I would be interested in the report that the stick force per G actually got down to the true zero load per-G, in a Service released aircraft.
Also, are you saying that "bob weights were added to the 85gal equipped Mustangs" as a mandatory mod for use of the 85gal tank and ordinary "Mustangs" didn't have a counterweight? G-load counterweights on elevators are quite common on many aircraft.

Eng

 

[drgondog]

You might have a different report that describes the response in this specific case differently to the one in this thread?
I think you will find that the terms here should be very specific. In this case in the report, and what you describe, is not control reversal, it is changes in control loading, the aircraft still responds in the same sense to stick movement, but the stick load per G reduces with stick movement when the Cof G is too far aft and this is a difficult handling trait.

In this case - specifically reversal of controls occur in zero stick force per G range.

In layman term you find yourself pushing the stick (gently) to maintain bank.

I would be interested in the report that the stick force per G actually got down to the true zero load per-G, in a Service released aircraft.
Also, are you saying that "bob weights were added to the 85gal equipped Mustangs" as a mandatory mod for use of the 85gal tank and ordinary "Mustangs" didn't have a counterweight? G-load counterweights on elevators are quite common on many aircraft.

Eng

Paragraph 3 Conclusions (b) first page "

http://www.wwiiaircraftperformance.org/mustang/P-51B_Fuselage_Tank_4-43-23-1.pdf

If you have a copy of Ed Horkey's "The Real Stuff" see page 12 Plate II-1 where he discusses Longitudinal Stability relative to CG and shows cross over from Pull to Push in pounds per G acceleration.


A stick force reversal occurs at Zero force per G.