More 109 goodness

[Grits]

Off topic

[Squire]

There would have been little point to installing the "neg-g carbs" if they didnt do anything to help fix the problem, since they were fitted to the a/c. I have no doubt that the strombergs were the best solution in the end.

http://www.fourthfightergroup.com/eagles/spit9tactical.html

"The Spitfire IX is a Spitfire VC modified to incorporate a Merlin 61 engine fitted with the latest negative 'G' carburettor".

[Wotan]

straffo,

Read what Timras quoted from Price.

Here I will re-quote it:

" It would have been easier for the Spitfire IX to follow the Fw190 in a diving turn if its engine had been fitted with a negative 'G' carburettor, as this type of of engine with the ordinary carburettor cuts very easily."
[Spitfire IX-Fw190 tactical trials, Alfred Price: Fighter Aircraft]


" The problem of engine cutting under negative g had also been a great disadvantage in combat. The excellent Miss Schilling at the RAE, Farnborough, had already achieved a substantial amelioration of this problem but no means a full solution. I had no idea what the final answer would be but was sure I should press very hard it to be found ( It was, with the Bendix Stromberg carburettor, but it took a long time)."
[ Jeffrey Quill: Spitfire]

[Karnak]

Barbi,

Would you like an eneumeration of the Spitfire's failings?

Cramped cockpit
Poor visibility over the nose.
Poor visibility to the rear
Imbalanced controls.
Insufficiently rigid wing
High stick forces for aileron controls, particularly above 350mph indicated
Narrow track landing gear
Short fuel endurance
Rudder pedals excessively low in the cockpit
Insufficiently rigid cannon mounting points
Excessive radiator drag
Excessive cockpit drag

Mk Ia, IIa, Va: Insufficient firepower
Mk I, II, early V: Cloth ailerons very significantly reduce aileron effectiveness
Mk Ib, IIb: Completely unacceptable rate of jamming in the Hispano cannon installation
Mk I, II, early V: Float Carburator causing immidiate fuel starvation when negative Gs are applied
Mk V, F.Mk IX: Improved float carburator that only slightly staves off fuel starvation when negative Gs are applied.
Mk XIV: Excessive torque


Yup, I sure think it is flawless.

[Kurfürst]

Then I just wonder about the reasoning behind your extreme reactions when I note the same flaws - if you are just as well aware of them as I am.

[HoHun]

Hi Karnak,

>Sorry, but I don't have a scanner so I cannot post the chart that I got the Mosquito Mk IV performance off of.  You'll either have to take my word for it

I'll gladly take your word :-) But I'll still try to convince you that the Mosquito was faster than you think!

> If you want to believe that the Mk IV peaked at 12,000ft so be it.

First, I'm a bit confused about the PR. IV - I only know the B. IV series 1 reconnaissance variant which was called PR I. It seems the German edition of David Donald's "Bomber" accidentally omitted the PR IV , so I have been unable to figure out the characteristics of that version.

Since you mentioned the Merlin 21 engine, I thought it must have been boosted to more than +12 lbs/sqin, and full throttle height drops with altitude. I've got one scan from Air Publication 2019E, I & T indicating +14 lbs/sqin in M gear and +16 lbs/sqin in S gear for Merlin 21/23 which meets my expectation.

I have found another downloaded scan from an unidentified book listing Mosquito IV DG290/G (sic!) with Merlin 21 as getting 364 mph @ 11700 ft with 3000 rpm/+12 lbs/sqin - but that's carrying 2 x 1000 lbs. Obviously, it's a B. IV, but I figure the bombload was experimental and probably carried externally. The full throttle height again matches my expectations.

(Generally, the Mosquito could lose a larger percentage of its take-off weight than the single-engined fighters, so its top speed would vary considerably depending on the current weight status.)

For the B. IV, I've got the chart Nashwan mentions, though in supercharger high gear the boost is just +9 lbs/sqin at 22000 ft.

The good news: With +16 lbs/sqin, the full throttle height will drop but the Mosquito will go way faster :-) From very rough graphical extrapolation, I'd say at +16 lbs/sqin it should get something like 395 mph @ 13500 ft.

That's 636 km/h @ 4.1 km - the 670 km/h top speed "Rechlin" graph (which is simplified and not entirely accurate at that altitude) gives the Me 109F-4 speed at 4.1 km as about 625 km/h - less than the Mosquito's.

I hope you'll now accept the well-documented 670 km/h top speed as perfectly realistic :-)

Regards,

Henning (HoHun)

[MiloMorai]

Henning a Mossie website, http://www.home.gil.com.au/~bfillery/mossie02.htm

[Karnak]

Barbi,

Because my position has nothing to do with the Spitfire.  I'm much more interested in getting the facts right and the facts being presented in this thread do not match the facts of the historical events.

Henning,

I've never seen any numbers that high for a Mosquito Mk IV, PR or B models.  The De Haviland chart I have (at home, I'm at work) indicates low gear peaks at just over 15,000ft and high gear peaks at 22,000ft with the top speed of 380mph being achieved at 22,000ft.

I've never seen anything that indicates that a pre B.Mk IX Mosquito ever broke 385mph, even the lighter prototype, though it did easily out pace the Spitfire Mk V.

That your calculations arrive at 395mph at 13,500ft makes me wonder if your calculations might not be a bit optimistic.

[MiloMorai]

Barbi, you might what to have a talk with your good bud Bergström and straighten him out for he doesn't agree with your view of uber German a/c.

"The Allied fighters generally were superior to the German Bf 109 G and Fw 190 A in service in 1944."

[ATA]

Originally posted by MiloMorai

"The Allied fighters generally were superior to the German Bf 109 G and Fw 190 A in service in 1944."

Nahh.There were just more of allied fighters i think.

[HoHun]

Hi Karnak,

>I've never seen any numbers that high for a Mosquito Mk IV, PR or B models.  The De Haviland chart I have (at home, I'm at work) indicates low gear peaks at just over 15,000ft and high gear peaks at 22,000ft with the top speed of 380mph being achieved at 22,000ft.

Well, here's a graph indicated 385 mph @ 22000 ft:

http://hometown.aol.de/HoHunKhan/mosquito_speed.jpg

Note that this is for 3000 rpm, +9 lbs/sqin.

Here is a graph showing the dependence of boost on altitude:

http://hometown.aol.de/HoHunKhan/boost.jpg

(Static pressure, so all altitudes are a bit lower than in level flight with ram effect.)

You can see that for +16 lbs/sqin, the full throttle height is 7000 ft lower than for +9 lbs/sqin at 3000 rpm.

So you can now draw the speed curve from 22000 ft down to 15000 ft. Depending on how you judge the curvature, you end up at 390 - 395 mph.

(Graphical extrapolation is a rather crude tool here, but if you do the complete math, you'll get better accuracy but not vastly different figures.)

Here's the manual page showing that the Merlin 21/23 could indeed be operated at +16 lbs/sqin in an emergency situation:

http://hometown.aol.de/HoHunKhan/mosquito_notes.jpg

I have to admit I'm a bit suprised by the results, too :-) I really paid too much attention to the first speed graph when I analyzed Mosquito performance last year, probably because I didn't realize the impact of the data from the manual page.

Regards,

Henning (HoHun)

[Karnak]

Hmmm.  I'll have to go over my books again.  That first graph looks very similar to one in the book I have.

I'll admit that I have mostly given up on the Mosquito.  I spent as much as I could afford to and never was able to find anything that could explain how the Mosquito was ever seen as anything other than cannonfodder by the Germans.  All the official data I have managed to find says the FB.Mk VI aircrews who reported running away from 109s and 190s that couldn't catch them on the deck were smoking something narcotic.  The absolute best data I've seen for the Mk VI was 338mph on the deck and 378mph at 13,000ft, and that was with Merlin 25s which are much more powerful than the Merlin 21s or 23s on a B.Mk IV.

From reading the historical accounts I would guess the Mosquito FB.Mk VI would do 355mph on the deck.  That is, in any case, the claim made by it's crews.  Some claimed 375mph, but De Haviland says there was a known error in some airspeed indicators that caused it to read too high and that those claims were wrong.

I am less familiar with the B.Mk IV except axs a basis of comparison for the FB.Mk VI.

[GRUNHERZ]

Karnak it was simply a matter of tactics. I think the mossies were so effetive be ause they kept their speed up and attacked unexpextedly. With speed in the same range as defending fighters it's not at all surprising that they could get away so often even a roving enemy fighter tried to engage them.

I think the perfect world of AH overemphasizes the importance of 5mph top speed differences.

[HoHun]

Hi Karnak,

>The absolute best data I've seen for the Mk VI was 338mph on the deck and 378mph at 13,000ft, and that was with Merlin 25s which are much more powerful than the Merlin 21s or 23s on a B.Mk IV.

Well, the Merlin 25 could go to +18 lbs/sqin, so if the 21/23 was cleared for +16 lbs/sqin in high gear, that was actually not so far. The B.IV also benefitted from slightly better streamlining and was faster on the same power.

The key probably would be to find out the dates for the clearance of the +14/+16 lbs/sqin boosts. The Fw 190A-3 comparison chart is rather strange because it indicates +14 lbs/sqin in low gear, but only +9 lbs/sqin in high gear.

Regards,

Henning (HoHun)

[pasoleati]

Henning, according to Mossie "FB VI, FB XVIII & FB 26" pilot´s notes Merlin 25 was cleared for +25 boost with 100/150 fuel (giving some 2000 hp). Any info on sea level speed with that boost?