FIGHTER COMBAT COMPARISON No.2: Bf109E-3 vs Spitfire MkI

Shortround6 · Feb 9, 2013

There is a source for confusion here:

There are TWO DIFFERENT 109s.

With a LARGE difference in drag.

The Emil was a barn door, to be polite.

The F was a much better job, being some 40kph (or more?)faster at 5,000 meters (F-2 to E-3) power difference was??

Spitfire changed a bit over time too, usually more drag ( 20mm wing guns, larger radiators and such).

Picking isolated examples for different time periods doesn't tell us a whole lot.

109F probably had 5-10% less drag than a Spit V based off of fuel consumption at cruising speeds. But that doesn't really tell us what difference between an "E" and a Spit I or II was. Or the difference between a "G" with bumps and a Spit IX.

Tante Ju · Feb 9, 2013

Shortround6 said:
The Emil was a barn door, to be polite.

So, being a barn door at all, how was it so much faster than anything else out there, hmm? Even the Spitfire, with more power, could only match its speed...

The 109F had a much better engine. The F-2 with a 601N engine could do about 615 kph, the 109E with 601A engine about 570 kph. Then there was a the E with 601N engine, and given the power difference between the A and N, I reckon it did about 590-595 kph. So with the F they chopped down about 20 kph worth of drag. Its significant, but not breathtaking. The armored glass on the Spit worth about 10 kph alone did it not? We had this discussion not long ago about early PR Spits, these were cleaned up and achieved about the same with more or less the same airframe.

A simple challange. Find a Spitfire that is faster on equal power. Any Mark. Say mid-1942 you have early Spit with Merlin 61, about 1340 HP at SL, and early Gustav with restricted 605A (ca 1290 HP), Mark Niner goes about 500 kph, Gustav goes about 530 km/h... with much less power that is.

Or go back Emil and Mark One, both go about 570 kph at altitude, but the Merlin III is about 100 HP stronger at altitude than 601A... not bad from a barn door eh.

Glider · Feb 9, 2013

krieghund said:
Unfortunately an issue from the creation of the Spitfire was corrected with the wing for the Spiteful

What I always find interesting in this type of highlight are the bits that are not highlighted.
The first highlight starts [UIt had faults[/U] not highlighted is the line before when it states perfectly adaquate for the speeds they were flying mid war
In other words in late 1942 with speeds of approx 410 mph Supermarine were looking at the future. I don't know when FW and Republic started looking into the future for there new wing designs that evolved into the Ta 152 and P47H but it was probably around that time. No one is saying that the P47 or Fw190 had flawed wing designs. This observation also covers the second highlight

Third Highlight, Supermarine decided to try a low laminar wing, why not, it was a great success on the P51 and Hawker did the same to develop the Tempest. I would have been critical if they hadn't looked into it.

Not highlighed. The bit where the decision had been made that Mk 21 airframe with a suitable engine would meet the need for a high performance fighter. The new low drag wing to be added later during production

Next Highlight To obtain a roll aster than any existing fighter Again why not, the Spitfire had a decent roll rate but no one is pretending that it had the best in the world. its the one area a Fw 190 always had an advantage.

Glider · Feb 9, 2013

Tante Ju said:
So, being a barn door at all, how was it so much faster than anything else out there, hmm? Even the Spitfire, with more power, could only match its speed...

The 109F had a much better engine. The F-2 with a 601N engine could do about 615 kph, the 109E with 601A engine about 570 kph. Then there was a the E with 601N engine, and given the power difference between the A and N, I reckon it did about 590-595 kph. So with the F they chopped down about 20 kph worth of drag. Its significant, but not breathtaking. The armored glass on the Spit worth about 10 kph alone did it not? We had this discussion not long ago about early PR Spits, these were cleaned up and achieved about the same with more or less the same airframe.

A simple challange. Find a Spitfire that is faster on equal power. Any Mark. Say mid-1942 you have early Spit with Merlin 61, about 1340 HP at SL, and early Gustav with restricted 605A (ca 1290 HP), Mark Niner goes about 500 kph, Gustav goes about 530 km/h... with much less power that is.

Or go back Emil and Mark One, both go about 570 kph at altitude, but the Merlin III is about 100 HP stronger at altitude than 601A... not bad from a barn door eh.

Certainly
Me 109 E3 - 1,100hp 355 mph, Spitfire I Merlin III with 87 Octane 1,030 hp 353 mph, I think we can call that one a draw

Me109 G6 - 1,455hp 398 mph at 20,700ft Spit IX merlin 61 1,565 hp 403 mph at 27,000ft again close to a draw

Me109 K4 - 1,775 hp 442mph Spit XIV Griffon 65 2,035 hp 447 mph edge to the 109

However the key thing is that the difference wasn't that much. As you have pointed out yourself the Spit is a much bigger aircraft with a larger wing so you would expect the 109 to have the edge using this crude method but its close.

I suspect the theory is impacted by a number of factors.
In the BOB the Spit 1 had 100 octane fuel which increased the engine power to 1,300 h with little or no difference in the headline max speed. It did significantly improve the max speed at lower altitudes and climb but not at the rated engine speed. This leads to a misleading comparison if you just compare Hp to speed.

Similar to later versions of the Spit IX. They often had hgher powered engines with little difference to headline speed because they were tuned to low altitude performance.

It just shows that if you want to use crude measures you get crude results.

tomo pauk · Feb 9, 2013

Shortround 6 is, as usually, on the money.

My 2 cents: We see here a comparison of a 'small' fighter (Bf-109), in several flavors, with a 'medium-sized' fighter (SPitfire), also several variants. Wing area of the Spitfire, standard wing, was 242.1 ft2, wing are of the Bf-109G was 173.3 ft², ie. about 3/4 of Spitfire's. The bigger plane need to be a darn streamlined job, if the drag (as force, not coefficient (Cd)) is to remain in the ballpark. Or, the drag will be about the same if the streamlining of the smaller plane is not that good. IMO, that was the case when we compare the Spitfire with Bf-109E. The speed was at the ball park, the engine power too (not, as Tante Ju believes, that Emil was the one with 100 HP less), both planes using 1940 state of the art props exhaust stacks. That directs us that smaller plane is less streamlined. Germans knew that very well, hence they made Friedrich (retractable tailwheel, shallow radiators, no tail strut, compete redesign of front of the plane), that was faster at same engine power than Emil.
We can also note that Spitfire's wing was, at root, only 13,2% thick, so maybe the laminar flow wing was not needed more than a rework of cooling system undercarriage covering?

Hi, Glider,
Was it really so that Tempest have had laminar flow wings? IMO that's very unlikely, esp. since the Sea Fury was so good carrier bird, with less wing span area.
The laminar flow wing P-47 was the XP-47F, 1st delivery on Sept 17th, 1942. Again, the P-47 was one of the fastest airplanes (or the fastest, from the time of introduction?) even with it's standard airfoil.

added: the Emil have had at disposal 1000 PS at 12900 ft, or 1020 PS at 14760 ft, depending on DB-601A version. Spitfire I was 1030 HP (1044 PS) at 16250 ft. So the Spitfire was having edge in power.

Glider · Feb 9, 2013

I certainly could be wrong as this isn't my strong suite but its my belief that the low drag laminer wing was the major defining feature of the Tempest. Of course there were others but that was the key one.

tomo pauk · Feb 9, 2013

It was certainly the wing that gave it the edge vs. Typhoon. Wing being only 14,5% thick (= 5 in thinner than that of Typhoon, the Typhoon's wing was 19.5% thick at the root), maximum thickness was at 37,5% of the chord (30% of the chord for Typhoon).

The 'Mustang' by Gruenhagen gives the 'minimum pressure at 0.4 chord' for the P-51's wing, that would mean the max thickness was at 40% of the chord?
The max thickness was 16,5% at the root.
added: the pg. 40 of Gruenhagen's book confirms the 40% figure

krieghund · Feb 9, 2013

Glider said:
What I always find interesting in this type of highlight are the bits that are not highlighted.
The first highlight starts [UIt had faults[/U] not highlighted is the line before when it states perfectly adaquate for the speeds they were flying mid war
In other words in late 1942 with speeds of approx 410 mph Supermarine were looking at the future. I don't know when FW and Republic started looking into the future for there new wing designs that evolved into the Ta 152 and P47H but it was probably around that time. No one is saying that the P47 or Fw190 had flawed wing designs. This observation also covers the second highlight

Third Highlight, Supermarine decided to try a low laminar wing, why not, it was a great success on the P51 and Hawker did the same to develop the Tempest. I would have been critical if they hadn't looked into it.

Not highlighed. The bit where the decision had been made that Mk 21 airframe with a suitable engine would meet the need for a high performance fighter. The new low drag wing to be added later during production

Next Highlight To obtain a roll aster than any existing fighter Again why not, the Spitfire had a decent roll rate but no one is pretending that it had the best in the world. its the one area a Fw 190 always had an advantage.

Sorry for the confusion I had used this in a previous forum discussion about the wing and its roll rate..but it was the wing redesign bit I really wanted to get across....had prop fighters not been eclipsed by the jets I believe the Spiteful would have made its mark!!

krieghund · Feb 9, 2013

Tante Ju said:
So, being a barn door at all, how was it so much faster than anything else out there, hmm? Even the Spitfire, with more power, could only match its speed....

Of course with a little "Vorsprung Durch Technik" and the same engine one could go quite a bit faster.............

Glider · Feb 9, 2013

No problem I should have toned down the comments. Apologies

Had for some reason the Jets not arrived for a few years the UK would have been in very good shape. The Hornet, Tempest II, Spiteful and Sea Fury for the Navy, were a pretty good combination that would take some beating

Kryten · Feb 9, 2013

krieghund said:
Of course with a little "Vorsprung Durch Technik" and the same engine one could go quite a bit faster.............

The 109 coupled a large engine with a small airframe, growth potential was less than the larger Spit, I wonder how far the He100 could have been developed?

also would the He100 have had the Me109's structural weaknesses?

Shortround6 · Feb 9, 2013

Tante Ju said:
So, being a barn door at all, how was it so much faster than anything else out there, hmm? Even the Spitfire, with more power, could only match its speed...

The 109F had a much better engine. The F-2 with a 601N engine could do about 615 kph, the 109E with 601A engine about 570 kph. Then there was a the E with 601N engine, and given the power difference between the A and N, I reckon it did about 590-595 kph. So with the F they chopped down about 20 kph worth of drag. Its significant, but not breathtaking.

Perhaps I was in error, however an old William Green book ( correction welcome) says that in a comparison between an 109F-0 and a 109E-4/N using similar power plants (?) the F-0 could could complete a 360 degree turn at 1000 meters in 18 seconds compared to the 25 needed by the E-4/N, From 1000 meters in a combat turn it could gain 2,900ft compared to 1,970ft, Initial climb rate went from 3,420ft/min to 3,730ft/min and time to 16,500ft (5000 meters) dropped from 6.1 minutes to 5.2 minutes.

Is the "F" that much lighter or was the reduction in drag responsible?

Tante Ju said:
The armored glass on the Spit worth about 10 kph alone did it not?

Yes. Early Spits could do about 585-590kph.

Tante Ju said:
Or go back Emil and Mark One, both go about 570 kph at altitude, but the Merlin III is about 100 HP stronger at altitude than 601A... not bad from a barn door eh.

As has been noted the difference is not quite 100hp (could 60 hp or under?) depending on the version of the 601 and the speed on the 109Es seems to vary from 555kph to 570kph. With the 109s smaller wing (73%) and smaller fuselage it sure doesn't look like it has much less drag than a MK I Spit.

krieghund · Feb 10, 2013

Kryten said:
The 109 coupled a large engine with a small airframe, growth potential was less than the larger Spit, I wonder how far the He100 could have been developed?

also would the He100 have had the Me109's structural weaknesses?

Well there was a larger wing in the works to anticipate a weight increase, the MG151/15 could be fitted (I would opt for three), its only real weakness revealed was that the landing gear struts needed beefing up and V4 was dived to 850 kph. The structure was already flown to 746 kph with a reduced wing span. I would have gone to a conventional oil cooler and used the methanol cooling evaporators for extra cooling of the engine as the special Ki-61 had shown that this extra area of cooling surface was more than adequate for the DB601. Also the cooling system was low pressure and leaky as it was and damage to the cooling panels was not going to result in a catastrophic engine failure as experienced in a high pressure radiator equipped aircraft. Contrary to some publications, all He100's were produced with the evaporative systems with the production models having a retractable auxiliary radiator for ground running, takeoff and climb.

It is also interesting to note that the He100 was used as a chase plane for the jet aircraft tested at Reichlin.

The Bf109 bested the He112 but Heinkel came back with the He100 to best it, however, the world is fortunate that in many instances the RLM viewed the world through their belly button, politics not withstanding.

stona · Feb 24, 2013

I've decided to have a go point by point astime allows

I wrote

"Shenstone worked hard on the wing/fuselage join area,where on a normally shaped aircraft lift degenerates and speed sapping turbulence and drag occurs,especially under high propeller power effect.Perfecting this area preserved curvilinear lift distribution by continuing the wings lifting effect and lowering fuselage interference drag turbulence to astounding levels."

The reply was.
.
"Again, nothing special in this. Most designers paid careful attention to this."

Obviously not enough in the case of the Bf 109. H.Muttray in "Die Aerodynamische Zuzammenfugung von Tragflugel und Rumf" published in 1934 showed the benefits of a well designed wing fillet (for the reasons I originally gave) and demonstrated that it was important for the radii of the fillet to increase towards the rear.
This feature is absent from the Bf 109. Sighard Hoerner in "Fluid Dymanic Drag" calculated that 5% of the Bf 109's total drag stemmed from this area. He also calculated that,given more careful design of this area,along with a general "clean up" the Bf 109 could have flown 20 mph faster.

Shenstone paid particular attention to this area of the Spitfire and it was certainly something special that he achieved here.

Cheers

Steve

cimmex · Feb 24, 2013

I cannot agree, not many planes show a similar wing fuselage joint as the Spitfire, maybe the
I-16. What's about P-51, P-47 or Tempest, Spiteful to name only a few.
cheers
cimmex

Shortround6 · Feb 24, 2013

A lot of it has to with HOW/WHERE the fuselage-wing joint is. A wing coming out of a slab sided fuselage at mid fuselage needs little or no fillet. A wing coming out of a fuselage in the low/mid position needs a "small" fillet depending on exact contours of the fuselage at that point while a fuselage that is essentially sitting on top of the wing (or hanging from it which is why true high wing aircraft lost favor) need larger a fillet.

Fillets require a bit (a lot?) of hand fitting and have compound curves (usually) which add to the difficulty of manufacture and maintenance. you seldom get something for nothing.

stona · Feb 24, 2013

cimmex said:
I cannot agree, not many planes show a similar wing fuselage joint as the Spitfire, maybe the
I-16. What's about P-51, P-47 or Tempest, Spiteful to name only a few.
cheers
cimmex

Read Muttray,it's in German. I'm not an aerodynamicist.

stona · Feb 24, 2013

Shortround6 said:
A lot of it has to with HOW/WHERE the fuselage-wing joint is. A wing coming out of a slab sided fuselage at mid fuselage needs little or no fillet. A wing coming out of a fuselage in the low/mid position needs a "small" fillet depending on exact contours of the fuselage at that point while a fuselage that is essentially sitting on top of the wing (or hanging from it which is why true high wing aircraft lost favor) need larger a fillet.

It's far more complicated than that.

Cheers

Steve

stona · Feb 24, 2013

Next the famous "washout".
It was a stated previously a known factor and common to many wings. It dates back to the examination of seeds (Zanonia Macrocarpa) by Ahlborn around the turn of the 20th century. Wing warping,creating a twist,was well known to the early gliders like Etrich ( who called his gliders "zanonia") and Lillienthal. Men like Hill,Dunne Lippisch and Weiss as well notably Frederick Handley Page with his German aerodynamicist Lachmann all looked into it and tried it on various designs. Lachmann incidentally started a furious debate in the 1930s over the relative merits of his preferred tapered wings and other shapes,particularly those based on ellipses.Anyone who understands the Lotz method of calculus will enjoy the letters and debate in Flight magazine in 1936/7
Essentially it is a twist in the wing that allows the airflow between root and tip to stay attached longer and flow better over the wing's surface. The remarkable factor in Shenstone's Spitfire wing is the small amount of "wash out" applied to achieve this. On a loaded Spitfire wing the washout is +2 degrees at the root and - 0.5 degrees at the tip,a total twist axis of only 2.5 degrees along the wing.More "washout" equals more drag.
It is again a remarkable achievement.

Next maybe Shenstone's brilliant unequal chord aileron design.

Cheers
Steve

Shortround6 · Feb 24, 2013

stona said:
It's far more complicated than that.

I don't doubt that it is.

But you can't point to planes with different type/position wing to fuselage joints/intersections and claim that because they don't use a large fillet that NO type of wing to fuselage joints/intersections needs/benefits from large fillets. Or that one type/size fillet fits all wing to fuselage joints/intersections.

I am sure no Aerodynamicist and don't pretend to know more than the ones who were paid to design the planes at the time. I figure most of them had pretty good reasons for doing what they did but at times there may have been conflicting requirements.

FIGHTER COMBAT COMPARISON No.2: Bf109E-3 vs Spitfire MkI

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