Dewoitine D.520 VS Heinkel He 112, which one has more development potential (2 Viewers)

[Gilder]

The Bloch 152/155 airframe was limited to 1300 hp maximum, hence the changes when going to the 157, so they didn't really have much potential beyond 1940-41, as Bloch did anticipate. The intended armament was actually 2x20mm and 4x7.5mm MGs.

Fair point but my source mentioned 2 x Lmg but as they were never fitted, its of no importance.

I believe you meant to say "development potential" in your sentence about D520. Yet the French projects before and after the Armistice indicate that the D520 airframe could handle powerful engines with the normal structural changes that affected other fighter aircrafts. Even ignoring the intended switch to D551-style airframes, it could at least broadly match the development potential of a Bf 109 and other small fighters, even if it would never have the advantages of big fighters.

Re the D520 I admit to being doubtful. When fitted with the Merlin the D521 had considerable cog issues coupled with stability problems at low speeds, resulting in the project being cancelled after six flights. The Merlin wasn't a big or heavy powerplant and I cannot see the airframe handling anything larger without serious issues. That or a rebuild along the lines of the Bloch 157.

 

[Shortround6]

In some of these discussions we are talking about generalities.
And with generalities we can always find exceptions.
Do the exemptions prove the "rule" or do the exceptions prove the rule is false?

I like using the P-40 as an example, in part because it was just a P-36 with a V-12 engine. So the aerodynamics, while very good, are not advanced like the P-51. Wing flaps are pretty basic, a bit better than the Spitfire and about equal to the Hurricane, not as good as many other planes. Early P-40s were pretty zippy for the 1090hp engine and the 6800lb weight.
Now without actually changing the size of the airplane (wingspan, length, wing area, size of fuselage) the US rapidly ran the weight up to over 8,000lbs without much gain in power. In the 15,000 to 20,000ft range)
In part due to BP glass, armor and self sealing fuel tanks. and the weight of guns and ammo that would have collapsed the landing gear of a lesser airplane

Spitfire and Hurricane got big wings, not so much to put the eight machine guns in (although the size helped) but to get the 5,000-5300lb airplanes out of and into the standard British fighter fields of the time. Getting out was also a product of the fixed pitch propellers, long take-off runs at about 2/3rd throttle.
P-36 carried about 1/2 the armament (one .50 being about 1/3 the weight of the .30cal guns). US was using at least two pitch props in the 1937 P-36 order (maybe constant speed?)
Gross weight was about 5600lbs with 105 (?) US gallons. Plane would hold about 160 gal overloaded for ferry use and some combat maneuvers were restricted.
See how confusing it is already
Bf 109 was designed to carry either 2 7.9mm MG OR a single 20mm cannon (not adopted) using the jumo 210 engine (600-700hp) so the small airframe worked. They did keep stuffing more things (bigger engine, more guns, more fuel). It did hit limits in late 1941/early 1942 and then it was a problem of trying to retool during a war and loose production or to grin a bear it. Being on the defensive helped. The Enemy (the allies) came to the Germans, the Germans did not have to fly very far to reach the allies.

YAK-9 got the big increase in fuel when they got metal spars in the wing instead of wood. The thinner spars had more room between them so they could fit bigger tanks in the same space or push the tanks further out into the wing. YAK-1 about the same weight as Hurricane I (summer of 1940) Take-off and landing runs of the YAK-1 were longer than the Hurricane runs. How much was the higher landing speed and how much were the brakes?
A YAK-1 would have been an "interesting" airplane to try and operate off a carrier

MC 202 was another legacy airframe. Use as much of the MC 200 radial engine as you can while reducing the height of the fuselage. MC 200/202 had the two fuselage mounted machine guns with 400rpg (?) Swap 20mm for the two 12.7mm guns? cut way down on the 12.7mm ammo? Yes one of the 205 versions managed to get a cannon in the prop hub, How much time did it take?

More power can reduce take-off runs. Landing is harder.

Things for the US would have been harder without the near oceans of bulldozers the US had.

What was important to each air force at different times in the war changed. Many air forces were forced to make do with planes that were already in production with modifications, not what they would have asked for if allowed a clean slate.

 

[Juha3]

Personally I believe that the D520 lacked real development due to its limited size and equally limited performance in combat. The He 112 had a good performance with a fairly underpowered engine which I understand was considerably better that the comparably powered Me109D, and had a lot of potential which wasn't realised.

From the French side the Bloch 152 / 155 again had potential but unless France had the opportunity to equip it with a modern (Merlin equivalent) engine, its potential would never be realised. That said a version with the Supercharged Gnome-Rhone 14R engine was flown in March 1942 known as the Bloch 157

The Bloch 157 had the following stats-

Max Speed 441mph at 25,750 ft
Range 683 mph
Time to 26,000 ft 11 minutes

Note that she wasn't armed for the above flight and I don't know about armour or other military equipment, but the proposed armament was 2 x 20mm and 2 x Lmg. In 1943 she was given to the Luftwaffe who took the engine out for tests and she never flew again.

As I recall, Romanian pilots did not hold their He 112Bs in high regard. The aircraft's use as a fighter against the USSR in the summer of 1941 was short-lived. The Hurricane Mk I fared better in Romanian hands.

 

[Steamed_Banana]

In some of these discussions we are talking about generalities.
And with generalities we can always find exceptions.
Do the exemptions prove the "rule" or do the exceptions prove the rule is false?

I like using the P-40 as an example, in part because it was just a P-36 with a V-12 engine. So the aerodynamics, while very good, are not advanced like the P-51. Wing flaps are pretty basic, a bit better than the Spitfire and about equal to the Hurricane, not as good as many other planes. Early P-40s were pretty zippy for the 1090hp engine and the 6800lb weight.

This 'zip' only came about after a wind-tunnel session and subsequent series of modifications. The ailerons were also modified to allow better high speed roll (P-36 rolled very well at low speed but not about 250 mph) and the flaps were much more sophisticated than the Spitfire and arguably more so than the Hurricane. The Spit was just all up or all down, the Hurricane had intermediate settings, the P-40 had a switch on the joystick (activated by a lever on the side) which allowed rapid deployment of flaps to any setting from 0-100%.

Perhaps not as good as having a combat flaps setting or (better still) automatic maneuvering flaps but it did allow the pilot to set any amount they wanted to quite easily. And apparently the flaps worked at partial settings at relatively high speeds.

Now without actually changing the size of the airplane (wingspan, length, wing area, size of fuselage) the US rapidly ran the weight up to over 8,000lbs without much gain in power. In the 15,000 to 20,000ft range)

But as we know, increasing to ~1570 hp (officially) at below 8-10,000 feet, depending on atmospheric conditions

In part due to BP glass, armor and self sealing fuel tanks. and the weight of guns and ammo that would have collapsed the landing gear of a lesser airplane

Fuel was always useful, when needed. It's debatable how many guns and how much ammunition were needed. Same for armor etc. Guns in the nose did tend to be more accurate, it seems. Especially hub cannons.

Spitfire and Hurricane got big wings, not so much to put the eight machine guns in (although the size helped) but to get the 5,000-5300lb airplanes out of and into the standard British fighter fields of the time. Getting out was also a product of the fixed pitch propellers, long take-off runs at about 2/3rd throttle.
P-36 carried about 1/2 the armament (one .50 being about 1/3 the weight of the .30cal guns). US was using at least two pitch props in the 1937 P-36 order (maybe constant speed?)

P-40 had constant speed propeller as did the P-36.

Gross weight was about 5600lbs with 105 (?) US gallons. Plane would hold about 160 gal overloaded for ferry use and some combat maneuvers were restricted.
See how confusing it is already

It's not really that confusing. Multiple fighter types including the P-51 and the P-40 had fuel tanks which were used for the first leg of long flights, which were often over friendly territory. If attack over their own airfields was likely these tanks were typically not filled. Same with external tanks.

Bf 109 was designed to carry either 2 7.9mm MG OR a single 20mm cannon (not adopted) using the jumo 210 engine (600-700hp) so the small airframe worked. They did keep stuffing more things (bigger engine, more guns, more fuel). It did hit limits in late 1941/early 1942 and then it was a problem of trying to retool during a war and loose production or to grin a bear it.

Bf 109s seemed still very competitive through 1942. Their big issue was fuel / short range. The Germans needed but never developed a longer ranged fighter.

Being on the defensive helped. The Enemy (the allies) came to the Germans, the Germans did not have to fly very far to reach the allies.

The Germans were still very much on the offensive in the East through 1943. Americans tend to forget who was mainly responsible for defeating the Germans in WW2, (hint: it wasn't the US or England). The Siege of Leningrad was only partly alleviated in January 1943, and not fully lifted until a year later. The Battle of Kharkov was Feb-March 1943 and Kursk / Citadel was July-August 1943.

The difference is that while the Americans and British take it as axiomatic that a sustained strategic / heavy bombing campaign was necessary and worth expending resources on, the Germans, Soviets, and Japanese did not come to this conclusion, and the Italians and lesser Axis powers did not have the option due to limited resources. The Germans and Soviets in particular were mainly concerned with their own ground war and the conduct of frontal aviation, wherein the job of fighters was to establish air superiority over the very fraught, very dangerous, very dynamic and extremely huge battlefield on the ground so that their tactical bombers could harm the enemy and the enemy's tactical bombers could not harm them.

They did experiment with some kind of quasi-strategic bombing during the Battle of Britain of course, though they did not make a sustained effort to destroy British industry, they definitely could have used some longer-ranged but fighters (still effective in daylight combat, unlike the Bf 110) but they did not seem to see it that way and did not prioritize

The Stuka, Fw 190, Ju 88, Sturmovik and Pe 2 arguably had more to do with the outcome of WW2 than the B-24, B-17, Lancaster and Manchester bombers did.

YAK-9 got the big increase in fuel when they got metal spars in the wing instead of wood. The thinner spars had more room between them so they could fit bigger tanks in the same space or push the tanks further out into the wing. YAK-1 about the same weight as Hurricane I (summer of 1940) Take-off and landing runs of the YAK-1 were longer than the Hurricane runs. How much was the higher landing speed and how much were the brakes?

They didn't seem to have any problem operating Yak, Polikarpov and Lavochkin fighters from very forward, very primitive airfields, including during the winter when many German aircraft were grounded and those that were flying were doing so only through extreme effort and privation by German ground crews.

By contrast many Western made aircraft like the P-40, Spitfire, and Hurricane had trouble operating in the primitive conditions of the Soviet front, and the extremely long takeoff run for the P-47 was one of the reasons they declined to even field test it, considering it "not a fighter".

A YAK-1 would have been an "interesting" airplane to try and operate off a carrier

No doubt. So would a Bf 109, a P-51, or a P-38. Even Spitfires and Hurricanes made pretty mediocre carrier aircraft (and suffered a lot of mishaps), especially early on.

But as I already noted, there are pros and cons to specialist vs generalist designs.

MC 202 was another legacy airframe. Use as much of the MC 200 radial engine as you can while reducing the height of the fuselage. MC 200/202 had the two fuselage mounted machine guns with 400rpg (?) Swap 20mm for the two 12.7mm guns? cut way down on the 12.7mm ammo? Yes one of the 205 versions managed to get a cannon in the prop hub, How much time did it take?

I think it was more a matter of perceived need and priority. For whatever reason, the Italians were fine with two 12.7mm machine guns firing through the prop hub. The MC 202 had a good combat record in North Africa and the MTO, including against very heavily armed fighters like the Hurricane IIC and P-47.

More power can reduce take-off runs. Landing is harder.

I really haven't seen or read any reports of Yak or MC 202 fighters having trouble on short or primitive airfields. To the contrary. Have you?

Things for the US would have been harder without the near oceans of bulldozers the US had.

What was important to each air force at different times in the war changed. Many air forces were forced to make do with planes that were already in production with modifications, not what they would have asked for if allowed a clean slate.

Well that's always true, no argument there.

 

[Shortround6]

Several posts to handle this.
Again we are confusing things bringing in certain exceptions to general trends.

This 'zip' only came about after a wind-tunnel session and subsequent series of modifications. The ailerons were also modified to allow better high speed roll (P-36 rolled very well at low speed but not about 250 mph) and the flaps were much more sophisticated than the Spitfire and arguably more so than the Hurricane. The Spit was just all up or all down, the Hurricane had intermediate settings, the P-40 had a switch on the joystick (activated by a lever on the side) which allowed rapid deployment of flaps to any setting from 0-100%.

Perhaps not as good as having a combat flaps setting or (better still) automatic maneuvering flaps but it did allow the pilot to set any amount they wanted to quite easily. And apparently the flaps worked at partial settings at relatively high speeds.

A lot of 1935-39 fighters needed tweaking in wind tunnels to get good performance, some were tweaked without wind tunnels by using a number of test flights to sort out things like (but not limited to) radiators.
I don't want to get go deep into flaps. However split flaps are a type of flap that have similar characteristics which are different than plain flaps which are different that slotted flaps and different than other types of flaps. Spit flaps were pretty much the earliest service flaps but it only took around 7-8 years to go from simple split flaps to double slotted fowler flaps. A lot depends on the design team, actual goals of the design and the year.
Problem is that you can't swap flaps on an existing wing. Wing spar/s and locations would have to changed. Different flaps exert different loads on the wing and wing spars.

But as we know, increasing to ~1570 hp (officially) at below 8-10,000 feet, depending on atmospheric conditions

A sidetrack. I am trying to talk about design and/or design choices. P-40 is interesting from a design perspective. Like power for the speed considering the size and weight of the plane. It does show how bad the Bf 109E was. Using power that did not exist when the design was being done (P-36 remember) is not a good way to evaluate the design.

Fuel was always useful, when needed. It's debatable how many guns and how much ammunition were needed. Same for armor etc. Guns in the nose did tend to be more accurate, it seems. Especially hub cannons.

Requirements changed with time. So did available power. So did available guns. What is a lot harder to change is the size of the airframe.

P-40 had constant speed propeller as did the P-36.

And that can affect the wing and/or flap needed to get the desired take-off performance. US was leading the world in propeller design in the mid-late 30s. US was also less limited than most when it came to airfield size.

It's not really that confusing

It is confusing.

Making a fighter plane that has enough room/volume to hold 55 US gallons, even if not used for combat is going to different that a fighter plane not required to hold the "extra" fuel.
P-36 fitted a similar size tank (dented and stretched) behind the pilot's seat.
Adding 300lbs or so of fuel is also going to affect take-off and some air forces in 30's would have different requirements/restrictions. Not talking about combat, just routine transfers/training.
Trying to guess what different air forces requirements/requests were without documentation is hard.

 

[Steamed_Banana]

The whole issue of flaps is super interesting to me, and you are right those are split flaps which do have some limitations.

As far as the fuel goes, I agree - i'm just noting that the 'less than ideal' compromise of having extra fuel in places that made the plane hard / dangerous to fly was a common solution to the problem of needing more fuel. The more I learn about WW2 aircraft the more astonished i am about the incredible amount of fuel they use. I think about it every time i fill up the 16 gallon gas tank in my car!!

 

[Shortround6]

Continuing

Bf 109s seemed still very competitive through 1942. Their big issue was fuel / short range. The Germans needed but never developed a longer ranged fighter.

This really points some of the problems with 'small' fighters. 109 is another good example seeing as how there 3 (at least?) different 109s. The early Jumo powered version.
The 109E and the 109F and later versions. Early 109s (Jumo 210) had 255-270 liters. Fitting in a 400 liter tank was fairly easy. Finding room for fuel for 1400-1500hp engines instead of 1100-1200 hp engines was going to hard. Granted cruising used similar fuel burns.
Germans needed to increase the fire power of the 109 in 1942. How the Germans were to do that while fitting the larger engines and more fuel in an airframe designed fpr 2 machine guns and 700hp was amazing. Expecting more is really pushing things.

The Germans were still very much on the offensive in the East through 1943. Americans tend to forget who was mainly responsible for defeating the Germans in WW2, (hint: it wasn't the US or England). The Siege of Leningrad was only partly alleviated in January 1943, and not fully lifted until a year later. The Battle of Kharkov was Feb-March 1943 and Kursk / Citadel was July-August 1943.

There are different ways of being on the offensive. Germans and the Soviets were mainly contesting the area's over the battlefield. Neither side could really do much for deep penetration aside from doing just enough to keep the other side "honest". Keep some aircraft and AA guns in the rear areas.

They didn't seem to have any problem operating Yak, Polikarpov and Lavochkin fighters from very forward, very primitive airfields, including during the winter when many German aircraft were grounded and those that were flying were doing so only through extreme effort and privation by German ground crews.

By contrast many Western made aircraft like the P-40, Spitfire, and Hurricane had trouble operating in the primitive conditions of the Soviet front, and the extremely long takeoff run for the P-47 was one of the reasons they declined to even field test it, considering it "not a fighter".

Things changed a lot in just a few years and forward/primitive does not always mean short runways, getting a runway into a wheat field is a lot easier than putting one into a forest with 50-60ft trees. Getting a smooth surface is another story, keeping it smooth is a 3rd story. Bringing in the P-47 is stretching things.
US Army fighters when clean had take-off distances (on the runway) ranged from 1070ft (P-40E) to 2540ft for the P-47D-25. Even a P-61B only needed 2400ft.
P-39s needed around 1700ft.
Adding drop tanks or bombs could add a lot.
Now this is just take-off. Getting the planes back onto the runway is the other side.
Spitfire I with 2 pitch prop needed about 960ft but was only using 880hp (?)
Operating on the Russian front often requires interpretation. What was acceptable operational loss rate is often not given.
Hawk 75s in France during the phony war were having lots of trouble with French airfields, which were often short, lumpy and not well drained. French had ordered about 25% spare parts for their early hawk 75 orders. But by Jan 1940 they were looking to buy another 30 wing sets to replace wings damaged in landing and take-off accidents.
Getting replacement parts or replacement aircraft for lend lease aircraft may have been harder?
Britian used up thousands (many thousands) of tons of concrete and cut down lots of trees and flattened lots of building to extend existing airfield so comparing 1942-43 runway requirements to 1935-38 requirements doesn't work.
Evaluating problems on the Russian front needs more information.

No doubt. So would a Bf 109, a P-51, or a P-38. Even Spitfires and Hurricanes made pretty mediocre carrier aircraft (and suffered a lot of mishaps), especially early on.

At least the Spitfire and Hurricane could actually operate on carriers, unlike the American army aircraft.
Low wing loading was benefit. But the short landing gear travel compared to true naval aircraft was a real problem. Not often mentioned, but slamming land planes onto carrier decks repeatedly was going to be a problem. Trying to extend the landing gear on an existing design was going to require a lot of work.
Back to runway requirements, worst US Navy fighter (F6F-3) needed 950ft. 2nd worst needed 840ft (F4U-1D) Every other Navy fighter needed less than 800ft zero wind on hard surface.
You want a high speed fighter with a low power engine and you use a small wing to get the speed, you pay the price.

I really haven't seen or read any reports of Yak or MC 202 fighters having trouble on short or primitive airfields. To the contrary. Have you?

Yaks had trouble with the landing gear on all runways. Even to the extent that the landing gear sometimes folded up overnight with the aircraft parked.
Operating any aircraft on many North African airfields was problem.
Most NA airfields weren't restricted by obstructions (trees/building) near the runway.
I have found one source for take-off and landing distances for the MC-202
6206lb prototype needed 827ft to take-off and 771ft land. Heavier production aircraft would need longer.
Yaks needed around 1050ft, a lot depends on exact engine and gross weight (armament).
A Yak 7 needed around another 300-400ft compared to a Yak-1.

Handling bumps and ditches gets tricky. Braking without nosing over depends on a lot of things. Very few have anything to with the engine or with wing area or flaps.

 

[Gilder]

As I recall, Romanian pilots did not hold their He 112Bs in high regard. The aircraft's use as a fighter against the USSR in the summer of 1941 was short-lived. The Hurricane Mk I fared better in Romanian hands.

I have limited information on this but my belief was that the main problem was the underpowered engine and resulting lower speed and acceleration. Hardly surprising considered the engine they had. With a developed DB601 life could have been a lot different.
It still had a better performance than the Me109D which had a similar engine and didn't perform well against the French during the battle for France.

 

[Steamed_Banana]

The 112 was also not very agile and had no armor or SS tanks. There is a pretty good video on it's use by the Romanians on that Showtime112 channel.

 

[GregP]

Why would the He 1112 have not been agile? It had a nice thick wing, relatively short span, and sould turn as well as anything else.

Any actual evidence of lack of agility for the He 112? Perhaps it wasn't held in high regard becasue it was fragile? Or for some other reason not having to do with actual performance?

Let's look at the He 112 A-0 and Hurricane Mk IIC:

The He 112 in Wiki says 303 mph. The Hurricane Mk IIC says 340 mph. There are numerous books saying that while the Hurricane was supposed to go 340 mph. real-world units didn't and were lucky to hit 300 mph in-service. The notion isn't exactly shown in just one reference, it comes for a variety of references. So, the He 112 A-0 SEEMS to be about as fast as a Hurricane at around 300 mph.

The He 112 had a wing loading of just under 20 lbs./sq ft while the Hurricae was 33.8 lbs./sq ft, so the He 112 had 2/3 of the wing loading of the Hurricane and SHOULD have easily been able to out-turn a Hurricane, assuming normal circumstances. I've never seen a roll chart for the He 112 and have been assuming it doesn't exist. Wiki says the He 112 B-0 could out-turn the Bf 109 by a bit, had a faster roll rate, and better aerobatic agility. I know it is Wiki, but can you cite some reference for poor He 112 agility in practice?

Power loading for the He 112 is almost identical to the Hurricane MK IIC and is, in fact, slightly better than the Hurricane at 7.13 lbs./hp versus 7.35 lbs./hp.

All indications from specs are that the He 112 was decent performer. Since it was a low-run aircraft, maybe it was typical of early production machines and was hand-built, making it difficult to service with regard to parts interchangeability.

 

[Shortround6]

Uh, Greg, the Wiki entry on the He 112 is pretty much close to utter crap. It is for the 4th prototype or it is a mismash of information.
Source I have is William Green and could well be in error also.

The first HE 112 had the 250 sq ft wing and a span of 41ft 4in.
V2 and V3 got wings clipped by 40in, span 37ft 3/4 inches, area 232.5sq ft.
V4, V5, V6 and V-8 were also built with this wing.
V7 is supposed to be the first B series plane with a lot of weight taken out and a new wing of 183sq ft and a span of 29ft 10 1/4 in, Also used as a DB 600 test bed.
V9 is the pretty much the standard B series fighter with the small wing and Jumo 210Ea engine with a two bladed constant speed airscrew.
Wing loading was 27.1lbs/sq/ft ?

The only way you are getting a Hurricane up to 33.8lbs of wing loading is by carrying a pair of 90imp gal drop tanks.
A IIA (eight guns) clean was about 27.6lb/sq/ft. adjust as needed.

The 112 B-0 is supposed to hit 317mph at 15,420ft.
Hurricane IIC was supposed to be good for 336mph, about 6mph less than the IIA.
We can argue about fit/finish but the IIC tropical was supposed to be good for 320mph.
This should be for clean aircraft which means no bomb racks fitted which even if empty are going to cost some speed.

 

[GregP]

Hi Shortround.

I used the numbers for horsepower, weight, and wing area only for a comparison with the He 112 A.. I used anecdotal flight reports for the He 112 B-0 for maneuverability, roll, and climb.

The He 112 B series were decent airplanes and matched the Bf 109s of the time.

The wing loading were at max takeoff weight for both airplanes. You can, of course, limit them to half fuel and half ammo, but you have to compare SOMETHING.

 

[Shortround6]

The wing loading were at max takeoff weight for both airplanes. You can, of course, limit them to half fuel and half ammo, but you have to compare SOMETHING.

You are right, we do have to compare something.
For me it is gross weight clean. Or max gross weight clean.
We all know that at least some fuel is going to be burned off but it gives us a starting point.
Very few non-American planes used the part fuel and 1/2 ammo trick for official performance numbers but then most other countries carried as much internal fuel in their 1939-42 airplanes. Few other countries carried as much ammo. A few did.
Comparing a clean fighter to a fighter carrying a pair of ferry tanks is not quite fair though. Switching the Hurricane to combat drop tanks saves around 700lbs

I will say that I was in error. The Putnum Book "Hawker Aircraft since 1920" gives max gross weights but says that includes 90gal ferry tanks.
However REA performance charts give very close weights and say that is with 43 gal tanks.
IIB 7330lbs clean, 8110lbs with two 43 gallon tanks.
IIC 7560lbs clean, 8410lbs with two 43 gallon tanks.
I cannot explain the difference.

 

[ThomasP]

re

The He 112 in Wiki says 303 mph. The Hurricane Mk IIC says 340 mph. There are numerous books saying that while the Hurricane was supposed to go 340 mph. real-world units didn't and were lucky to hit 300 mph in-service.

FWIW

The sometimes quoted speed of 300 mph for the Hurricane is for the Mk I after it had seen hard use. This is usually a semi-quote from a statement made by Dowding regarding the Mk Is toward the end(?) of the BoB. New build were considered good for 315 mph with +6.25 lbs boost at 18,000 ft, or 325 mph with +12 lbs at 12,000 ft.

For comparison, SeaHurricane Mk IB (Hurricane Mk I with CS prop, catapult spools & tail hook mods, FAA radios) was considered good for 308 mph with +6.25 lbs boost at 18,000 ft, or 315 mph with +16 lbs boost at 7,500 ft.

336 mph with +9 lbs boost at 21,500 ft was considered to be the speed of the Mk IIC when new(ish). The minimum acceptable was supposed to be 330 mph - any less and the airframe was supposed to go to a MU for improvement when possible.

For comparison, the SeaHurricane Mk IIC (fully navalized) was supposed to be good for 320 mph with +9 lbs boost at 21,000 ft.

In theory, all of the above speeds were with 1/2 internal fuel and full ammo.

 

[GregP]

According to former Hurricane pilots, it wasn't that fast, EVER.

I've seen BOB pilots reports that say it could barely hit 300 mph in wartime trim, in large numbers. I mean normal in-service trim, as issued to front line units.

And those reports were not isolated. That makes me really wonder how accurate the top speed numbers bandied about in Wiki and other websites are.

The Planes of Fame operates anywhere from 3 to six P-51s, depending on what is flyable at the time. Most of the time, the former Reno racers Voodoo and Strega are not flyable since there are few air races these days. At the next one, we plan (at this time, anyway) to fly the Bardahl Special, if the word about the volunteers is any indication if truth. It is flyable, but is NOT anywhere close to "stock," and has parts from VooDoo on it. Our two "stock" P-51s are Spam Can and Wee Willy. We also fly a P-51A (Mrs. Virginia). but it is an Allison-powered airplane and is not directly comparable with the Merlin units.

I have heard from active pilots that when Wee Willy and Spam Can fly side by side. Wee Willy can stay glued to Spam Can using 2 inches less manifold pressure than Spam Can is using at the time. That means Wee Willy has less drag and is the faster airframe, but boith are essentially stock with stock powerplants. Well, as stock as it gets after 80 years of being out oif production for the Merlin engines, anyway.

Most fighters in-service in WWII were also such that some were faster and some were lower. In a mythical 420 mph fighter, I'd pexpect a top speed arange of 15 mph. That is some would likely go 410 mph and some would likely go 425 mph, with most being in the 415 - 422 mph range.

In the case of the Hurricane, 340 mph down to 305 mph seems excessive, but fits what I've read in MANY reports. Of all the front-line fighters, the Hurricane seems to have beeen slower-than-specified in large numbers, but it was available and serviceable., making it the primary fighter in the BOB. It performed admirably, but has never been known to be called fast.

The reports could be in error. true, but they are numerous.

The Bf 109E, likewise, is often quoted at 290 mph at sea level and 357 mph at altitude. I'd bet heavily that some were faster and slower by about the same amount (±7 - 8 mph) and maybe a few were slower or faster. But likely not as "slow" as the majority of Hurricanes since the Bf 109 was all metal and suffered less from surface finish variability than the Hurricane, which had the rear fuselage and control surfaces cover in doped linen fabric. Camoflague paint was draggy, as applied in early WWII in Britian, and the airfoil in the Huirricane was never a fast one, either. It was 19% thick at hte root, tapering to 12% at the tip. 19% alone is enough to belay any claims of being fast for the installed power.

Compare with the Bf 109 at 14.2 to 14.8% tick at the root, tapering to 10.5 to 11.35% at the tip, depending on variant.

 

[YavorD]

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I have heard from active pilots that when Wee Willy and Spam Can fly side by side. Wee Willy can stay glued to Spam Can using 2 inches less manifold pressure than Spam Can is using at the time. That means Wee Willy has less drag and is the faster airframe, but boith are essentially stock with stock powerplants. Well, as stock as it gets after 80 years of being out oif production for the Merlin engines, anyway.
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One should keep in mind the accuracy of the scale readings for manifold pressure is, in best case, +/- 1/2 inch. Furthermore, most probably, the aircraft were not flown at full throttle in Your example. Thus, there are a lot more factors in individual component settings involved. Two inch difference in manifold pressure readings is not excessive, in my opinion.
Best regards,
Yavor

 

[Shortround6]

When looking at Hurricane speeds we have a range of possibilities.
Mk I's
MK IIs
with and without tropical filters
With and without stores.
With and without empty racks.

I have no idea why that plane has one remaining "patch" over a wing gun.
Trials/test speeds are almost always done with gun muzzles covered and cartridge case ejection slots open.
Squadron combat reports of speed are in what condition? This goes for just about all aircraft. They rarely got faster with 50-150 hours on the airframe.
Hurricane without muzzle covers/patches is going to be slower than one with patches. Patches were not just for speed. They cut down on the airflow through the wing and helped keep the guns from freezing at high altitudes. How important that was on North Africa or Burma I don't know. Keeping dirt/sand out of the guns was important.

 

[GregP]

One should keep in mind the accuracy of the scale readings for manifold pressure is, in best case, +/- 1/2 inch. Furthermore, most probably, the aircraft were not flown at full throttle in Your example. Thus, there are a lot more factors in individual component settings involved. Two inch difference in manifold pressure readings is not excessive, in my opinion.
Best regards,
Yavo

These are museum airplanes and are rarely, but not never, flown at full throttle. Our P-51A, Mrs, Virginia, went around Reno at 363 mph with an Allison up front. It wasn't just loafing and that speed is pretty standard for max speed on a stock P-51D at Reno. The racers are 100+ mph faster, but not really the stock airplanes. That would be mostly the Bronze class.

No, they aren't at full throttle when cruising, almost by definition. And, before you ask, nobody is going to pull out two manifold pressure gauges from two different airplanes and compare them on a test stand just because we are curious. If they were my own airplanes, I wouldn't do that ... but it would be interesting to know the data, were it to be available. I'll grant you that.

Still, airplanes are like cars, boats, and anything else mechanical you want to race. Actual performance varies a bit for "identical" pieces of equipment. Look at the old Sports Renault class in the SCCA. They tuned them to have EXACTLY the same horsepower, and someone always won every race, even when others didn't make mistakes. Nature of mechanical beasts.

Cheers!

 

[Steamed_Banana]

There is an official British spec sheet somewhere showing Hurricane IIC with a Vokes tropical filter maxing out at about 300 mph.

But the He 112 was apparently not regarded as agile, may have been due to a poor roll (like the Hurricane)

 

[SaparotRob]

Was the He 112 the plane with an extensive wing installed cooling system?