Pflaz DIIIa - how good or bad it really was?

[bristol scout]

Hi guys,
I think the Pfalz was probably not really all that bad--better than mediocre I would say.

No less a person than McCudden (6th. Sept. and 19th. December 1917) had to give the Pfalz best when outmanoeuvred by them (and an Albatros)

Werner Voss scored (4-I think) on it---Peter L. Gray thought most of the stories maligning the machine apocryphal---The Pfalz could dive a good deal faster than any other German fighter---the same trait that French pilots loved in SPADS don't forget.

Question---Was the DV11 really so exceptional--or was it the combination of very good airframe with exceptional engine?---Always wondered.

Cheers,
Dave.

[Dan_San_Abbott]

Hi Bristol Scout:
I think the Fok.D.VII with the 180 Ps Mercedes D.IIIaü was not that exceptional, it only became exceptional with the 185 Ps BMWIIIa engine that produced at altitude 260Ps at 1500 rpm. That put it into a different class.
The Pfalz D.XII was powered with the Mercedes D.IIIaü engine as well as the Rol.D.VIa, both od these machine have said to be as good as Fok.D.VII with the same engine. The Rol.D.VIb with the 195 Benz BzIIIb engine was the equal of the Fok. D.VII with the BMWIIIa engine.
The problem with the Rolands was the construction of the fuselage, labor intensive and not easily built made them more expensive than the Fok.D.VII. The same is true for the Pfalz D.III, D.IIIa, D.VIII and the D.XII. Had they had steel tubing fuselages, there may have been a much different mix of aircraft at the front. The Albatros fuselage was less time consuming and more easily constructed the the Roland-Pfalz wrapped veneer fuselages.
Blue skies Dave,
Dan-San

[bristol scout]

Hi Dan-San,
Thanks--that confirms what I thought ---about the engine more than the aeroplane (a bit P51 Mustang like).

Now I wonder if the Albatros (BMW'd) would have been equally transformed----wing problem aside---or indeed the Pfalz D111?

I 'm not going anywhere with this--just sometimes feel not enough importance is attached to the engine

Cheers Dan-San,
Dave.

[mik]

From chris Hienz If you don,t know CLmax 1.4 is a good assumtion. If you Know stall speed and weight you can work out Cl max. Which from the above post (flaring at 46mph) would be about 1.5

[mik]

I have asked before but can anyone give me titles of books withe reliable performance data for ww1 aircraft. I have books which seem to mix the data for The pfalz D111 and the D111a. I find it hard to believe that a Pfalz D111a which looks very streamlined (for 1918) is so much slower than a very square looking SE5a. For me the difference in performance does not equate to the loss of 20hp.

[Chock]

If you really want to know from a reliable source, this is probably a very good bet:

The National Archives | The Catalogue | Quick reference | AIR 1/1977/204/273/60

Regardless of how streamlined things look, all externally rigged biplanes with fixed landing gear are as draggy as hell. We can hear that in the cliche 'screaming dive' sound effect you get in war movies of an aeroplane plunging earthwards. That sound is mostly the airflow in the bracing wires and other 'sticky out bits' of biplane aircraft, which is an effect the Germans enhanced with the wind-driven 'Trumpets of Jericho' siren they mounted on the landing gear fairing of the Ju-87.

For something to generate that kind of sound, it has to be messing with the airflow like crazy. So as you can imagine, the engine protruding into the airflow on the front of a Pfalz might well cause more drag than the flat fronted, but cleanly-cowled SE5a, and it would certainly screw up the low pressure airflow to the centre section of the upper wing to some degree. Ironically, the flat bottomed section of the boxy SE5a fuselage probably also meant it generated a bit of lift in comparison to the round fuselages of stuff like the Albatros and Pfalz, and such a similarly boxy fuselage profile may well have contributed to it on the DVII too.

Al

[Ransom E. Olds]

Another thought to keep in mind is that the German fighters with inline engines were larger and heavier than their Allied counterparts, largely because the heavier German engines required greater wing area to provide a wing loading comparable to the Spads and the SE's with their lighter Hisso engines. Ransom

[totalspoon]

Wing Area's

Fokker D.VII 20.50 m2
Albatros D.V 21.20
Pfalz D.III 22.17
Pfalz D.XII 21.70

Spad XIII 21.15

SE5a 22.84
Dolphin 24.46

The English Hisso's had more wing area than any of the German Mercedes D.III's

Spoon

[Chock]

If I recall correctly, I think the Hispano Suiza engines had quite a bit more alloy (as opposed to steel) in their construction than the German ones. I'm pretty sure much of the upper part of an HS engine was alloy with steel inserts for the cylinders, so they'd be considerably lighter than the Merc and Beemer engines as well as probably more likely to make an aircraft more stable since there is less weight above the thrust line.

As a rough comparison, the dry weight of a Merc DIII engine is 700lb, and the dry weight of a Wolseley Viper (basically a souped up HS engine) was 500lb. So you've got the typical German fighter lugging approximately the weight of another person along with them in comparison to the Brit SE5a, which of course is going to increase the wing loading and affect acceleration and all that malarkey.

McCudden, who was very familiar with the SE5/5a, reportedly said the Albatros was a bit of a handful when he test flew one. Dunno if he ever got his hands on a Pfalz to test out though.

Incidentally, out of curiosity, I ordered that document from the National Archives, if it has anything interesting in it, I'll let you guys know

Al

[Dan_San_Abbott]

Gentlemen:
As Chock has pointed out there was a distinct difference between the Mercedes and Hispano-Suiza engines. Adding a little more detail.
Weights from German documents. (without water, oil and propeller hub.)
Mercedes D.III 160Ps 265kg, 583lbs.
Mercedes D.IIIa 170Ps, 275 kg, 605lbs.
Mercedes D.IIIaü 180Ps, 285kg, 627lbs.
BMWIIIa 185ps, 285kg, 627lbs.

Hispano-Suiza Weights from French Data.
150 hp Hispano-Suiza 8Aa 185kg, 410 lbs., direct drive.
180 hp Hispano-Suiza 8Ab 194kg, 430lbs., direct drive.
200 hp Hispano-Suiza 8Ba 230kg, 510lbs., reduction geared.
Wolseley engines, British data.
Wolseley Adder W4B 200 hp, no weight, reduction geared.
Wolseley Python W4A 150 hp 455 lbs., direct drive.
Wolseley Python II W.4A 180 Ps, 490 lbs., direct drive.
Wolseley Viper W4A 200 hp 508 lbs., direct drive.
Blue skies,
Dan-San