Dewoitone 520 question

[Jack_Hill]

One fact lingers in my mind for years.
I saw D-520 in flying exhibitions twice at le Bourget, end 70's/beginning 80's'.
Times (magic times)when all aerobatics and all speeds were allowed.
Never been impressed in any of D-520 performing at all.
Except for elegance.
Pilot never bounced her in anyway, gently diving, pulling, gently turning, minimum revs required at anytime and so on. This man (always the same pilot, who finaly crashed with the plane...), for any unknown reason to me, handled the a/c with lots of care and prudence.

 

[Siegfried]

I don't mean to denigrate the French aviation industry for the D-520 shows two things: its potential and failure. My understanding is that the French Government nationalized its industry. It didn't work. The speed of the Me 109E3 with the 1170ps/cv DB601Aa was 355 mph. The D-520 managed 322mph on its 940cv engine. I've seen 347mph in Wiki but I doubt it.

Maneuverability is the same with the same methodical French tests claiming better responsiveness for the D-520 but also noting its viscous stall and spin characteristics compared to the Bf 109E (a damaged one at that)

The National Socialists had no problem with running free enterprise companies or government owned ones and their policy of aggressive competition was probably more effective than the nationalized quasi communised industry that France experimented with.

It looks like it would have taken France another 6-9 months to match German quality at around the time the Me 109F1 was entering service advanced versions of the D-520 might have matched the Me 109F1. Advanced versions of the HS 12Y (the HS 12Z) promising a massive improvement.

The range of the D-520 placed it in a class of its own however.

 

[Altea]

Hello,

The D-551 offered speed but in other ways it might be seen as retrograde. Smaller wing means higher wing loading, higher landing speed and larger turning circle

.
Smaller wings means drastic weight analysis. And maybe some sacrifice on firepower, range, protection. Whatever, 2150/13.97 = 153,9 kg/m², does not make a higher wing loading.

Retractable landing SKID means better streamlining and performance, what is does for ground handling??? View from cockpit is also a bit suspect.

Well, a skid for grass airfields in 1940, not as heretic as owerdays, moreover it could have been changed.

I am not as confidant that just sticking 100 octane fuel in the tank would have lead to big increases in power. Did the Hispano have the strength to stand up to the higher pressures in the cylinders without failing? Didn't the Russians narrow the bores a couple of mm and add weight? Poorer materials or engine wasn't strong enough?

It's gererally admitted that in its form the Hipano-Suiza Y-51, was at limits. It passed the cut (state test trials) maybe with a narrow margin, but passed anyway and was lauched in production at the end of BoF.

About russian evolution, it's unsurprising, since engines are generally modified and improved by little touches after return from experience, rather than planified peremptory programms.

That also means, soon or late HS designers should have been obliged to follow the same way...

Regards

 

[Jack_Hill]

was it a real emphasis or event budget for further D-520 developement and, worst, deployment ?
Here in france, such a debat still exist.
Sources are highly unreliable for politic reasons. (Isn't it ridiculous, 72 years after...?)
But, maybe, to politics eyes, such a failure and KO is still very hard to explain to french people who still care about WWII.
Yes, D-520 had high wing load, but Dewoitine firm could be easily capable of developping slats, simply copying bf-109's. Did they ? No.
Did HS12 had a real developement potential ?
If yes, at how much weight, fuel consumption cost ?
For how much power gain ?
At which reliability cost ?
How much structural modifications would have be needed for much bigger engine and fuel capacity integration, still increasing wing load ?
No one will ever know, cuz France was litteraly smashed within 15 days.
Most reliables sources says kill/loss D-520 as 3/1, wich is much more than pretty good.
Hummm, well, pilots fought more than their best. But such a ratio is so high i don't really believe it...
"We will win because we are the strongests" (french 1940 propaganda)
And BOOM!, 1940, may...
"Not any plane can pretend being spitfire or bf109"
Nostradamus, aviation treaty, 1520.

 

[Siegfried]

Yes, D-520 had high wing load, but Dewoitine firm could be easily capable of developping slats, simply copying bf-109's. Did they ? No.

From English language Wikipedia:

"Additional prototypes

The prototype was followed in 1939 by two examples: D.520-02 and 03, first flown on 9 January and 5 May 1939 respectively, featuring new sliding canopies, a larger tail unit, and longer Olaer manufactured undercarriage legs; they also omitted the Handley-Page slats fitted to the outer wings on 01."

So it seems they had some kind of problem with slats and maybe not enough time to solve it?

 

[Jabberwocky]

On the development potential of the HS-12Y:

The engine could certainly make over 1100 hp without too major a modification. The -30 and -50 engines were producing a little over 1050 hp in early 1940 and there are a few online sources that put the 89ter at 1200 hp in 1940.

HS-12Z, a more developed version of the engine, is reported as putting out anywhere from 1400 to 1800 hp, but I'm unsure just how different this engine was.

Soviet development also gives some indication as to how fare the engine could have gone. The M-100 was essentially a licensed-but 12Y and put out 850 hp, 950 hp in the form of the M-103 (basically a developed HS-12YBRS), 1000-1100 hp for the M-103A in 1941 and then up to about 1350 hp for the later M-105 engines (mid 1943 or so).


Reliability:

The HS-12Y derived M-105 was considered more reliable than the V-1710 and Merlins that the Soviets ran in their Lend Lease P-39s, P-40s, Hurricanes and Spitfires. I don't know how indicative this would be with relation to Western engines in general – apples to apples comparison problem. Soviet maintenance and reliability standards were quite different from Western ones.

Part of the problem was the sensitivity (at least in the Merlin) to lower octane Russian fuels and different grades of oil. Another was a lack of spares. Another problem was that the Russians simply didn't possess the same degree of experience on maintaining the western engines.

Over the Kuban, the Russians reported getting a little as 40 to 60 hours of life out of a Merlin before failures (big ones too, like throwing a con rod). Many of these were refurbished engines though, as the Spitfires supplied to the Soviets were often second hand. The Russians reported that the Merlins in the Hurricane and Spitfire were 'sensitive' and often didn't make specified power on Russian fuel.

V-1710 was considered a touch more robust but still "weak" in comparison to Russian engines in terms of reliability. Engine life varied considerably. Reports are that the TBO for Allisons in the P-39s in Russian service varied from 40 to 50 hours (initially) to about 100-130 hours once the VVS became more familiar with the engine and got more spares/better maintenance procedures (in 1944). In the P-40 the engine was reportedly susceptible to seizures due to metal ingestion.

In 1941/1942 the RAF was getting about 120-170 hours out of the engine its Kittyhawks in the Western desert (around 50-65% of expected engine life), and anywhere from 100 to 180 hours out of the Packard Merlins.

Much depends on the conditions and operation of the engine. A Soviet pilot stationed close to the front might be expected to spend much less time at lower cruise levels and more time at higher engine settings than a RAF pilot doing sea patrols and battlefield interdiction.

RAF in the ETO was getting up to 200-240 hours out of its Merlins, but these were much more pampered than the engines in Russia or the Western desert.

Interviews with Soviet pilots tend to point out that the Allison and Merlins ran much more smoothly than Soviet engines, with less noise, vibration and exhaust particularly at full power. Pilot interviews also tend to point out that the Allison or Merlin were 'weak' for the airframes they powered, which may say more about Soviet design philosophy than the engines themselves.

 

[Shortround6]

The Hispano was a big slow turning engine. It was 36 liters in displacement which means it was 33% bigger than a Merlin. THis means it didn't need any were near the boost to make it's rated power. It was also much lighter than the Merlin. This means you CAN NOT just up the boost using better fuel without it breaking.

It's development potential was severely limited unless you are French and also think the Renault Dauphine was one of the great cars of the last century.

There were at least 3 attempts to "improve" the Hispano 12 Y engine. all added at least 200lb if not closer to 400lbs of weight. ALL changed from the 2 valve heads to 4 valve heads, 2 of them went to fuel injection instead of the ridiculous 6 carburetor set up. I can't be bothered to look up the Russian V-16 and 107 induction systems.

The Russian V-105 used a narrower bore, a heavier crank, a two speed supercharger, 3 valves per cylinder, better fuel and still maxed out under 1300hp.

 

[Altea]

The link above suggests the tendency to turn when on the ground was due to lack of a tailwheel locking device ... and ity was corrected in later models.

At 3 points rolling, maybe torque moment seems rather high. Cf rudder.

But once in fligt line even on main wheels, everything is ok.

Regards

 

[Altea]

the speed of Emil was 345/355 mph, the french tested a captured Emil-3 and in the report noted that was faster.

Not exactly 345/355. Previous british tests showed 571 kph with fully enclosed radiators, and 532 kph with fully opened ones. Except over Spitsberg island on winter, i don't see where can you fly with enclosed radiators.
That mean a range from 330 to 355 mph.

On soviet tests, the three brand new serial 109 E, made 542; 546 and 548 km/h respectivly. The last two ones from the 5 commanded, were maybe never tested, or never recieved.

The experimental D-520 made 549 km/h, secund serial one 534 km/h.
It should be noticed that neither Klimovs, nor HS Y-31 had no WEP, CP etc... D-520 flew at their nominal "max cruise" power, this could not be said for the "Emil".
So what was the "E" performance on 30 min, or 60 min power settings, not in short runs ?

Conclusion: its good to do not take "baldders for lanters" * anymore, and to compare what is comparable...

* french popular proverb

Regards

 

[Tante Ju]

Not exactly 345/355. Previous british tests showed 571 kph with fully enclosed radiators, and 532 kph with fully opened ones. Except over Spitsberg island on winter, i don't see where can you fly with enclosed radiators.
That mean a range from 330 to 355 mph.

This report of German says Emil could flew max speed of ca. 570 km/h with radiator 1/4 open (streamline position) with the water temperatur constant 90 degree celsius (external temperatur was 5 celcius). 90 degree was permissable for DB engine, so I do no think opening radiator was required during full speed flight. Emil can maintain this speed for very long, not only "short runs".

Kurfürst - Meßprotokoll vom 26.4.38, Geschwindigkeit Bf 109 V15a

 

[Altea]

This report of German says Emil could flew max speed of ca. 570 km/h with radiator 1/4 open (streamline position) with the water temperatur constant 90 degree celsius (external temperatur was 5 celcius). 90 degree was permissable for DB engine, so I do no think opening radiator was required during full speed flight. Emil can maintain this speed for very long, not only "short runs".

Kurfürst - Meßprotokoll vom 26.4.38, Geschwindigkeit Bf 109 V15a

You call very long 5 min Kurzleistung?
I know kurfurst and his site enough to say that it is very helpfull, but somewhat tendencious, if not biaised...
Only by observing the general look of the curve, you can perfeclty see that it was a theorethical, not a measured one.

Regards

 

[Vincenzo]

for the DB 601A the difference of power from max continuos and 5' setting is 100 hp (from 1000 to 1100 hp) so probably also in max continuous the max speed is over 340 mph (easy 345 mph).
Also the 12Y had short time setting with higher rpm although i don't think is very usefull. also the DB601 is a large slow turning engine (it never got boost like the merlin). if the 12Y not had the power is not a fault of 109, but is right noted the eventual difference of time you can keep the max speed.

 

[Tante Ju]

You call very long 5 min Kurzleistung?

This was theoretical limit. In practice Kurzleistung can be used as long as engine limits (temperatur) is correct, which it was in trials. Of course engine wear will be higher.

If you know any circumstance that prevents use of Kurzleistung for long periods, please let you share.

Only by observing the general look of the curve, you can perfeclty see that it was a theorethical, not a measured one.

No, report clearly states it was measured test. Calibration of instruments 21.4.38, actual measurement flights the following day on Haunstetten four-way record track 22.4.38., and Augsburg airfield, pilot flying plane Dr.Wurster etc. All details given.

Also French CEAM tests clearly say the Dewo's cooling is insufficent, Me cooling is better. Dewo had to throttle back twice in climb because rising engine temperature.

b) Climb to 5.500 m. PG
The climb speed of the Messerschmidt is slightly superior. It has a quality that favorize it: the engine`s cooling is satisfactory, on the other hand the D.520 had to throttle back due to the increasing temperature of the coolant agent (once at 4500m and once at 3000). The climb of the 109 to 5.000 m took apprx. 6' 20".

http://kurfurst.org/Tactical_trials/109E_FrenchCEAMtrials/french_109e_tt.html

 

[Altea]

for the DB 601A the difference of power from max continuos and 5' setting is 100 hp (from 1000 to 1100 hp) so probably also in max continuous the max speed is over 340 mph (easy 345 mph).
Also the 12Y had short time setting with higher rpm although i don't think is very usefull. also the DB601 is a large slow turning engine (it never got boost like the merlin). if the 12Y not had the power is not a fault of 109, but is right noted the eventual difference of time you can keep the max speed.

Ciao
If you're a real italien, why do you bother using miles for german planes that used metric system as you do?
So suppose 570 km/h at 1100 hp. Reduction on 10% power makes 3.3% loss in speed at best. No?
Certainly more, since you will fly at a higher AoA, but without L/D values at that speed, who knows the induced drag increase...

So 570/ 1.033 or 1.04 makes 545-550. It works. Why not, it's look like russian tests...

Regards

 

[Vincenzo]

i'm italiano (born and ever lived here but my grandfather and my great grandfather acquired US citizenship or so is in family tales) i use miles because the speed of 109 was indicated in miles in (not my) previous post.
from 1100 to 1000 hp is ~ 10% (is 10% with base 1000) if the plane got 570 km/h (354 miles) with 1100 hp (metric) under cubic root laws it got almost (because commonly when used for up power was considerd at best so if we go for less power is at badest) 552 km/h (343 miles) with 1000 hp taking in the count the higher altitude of max continues setting it's easy that the speed is bit more.

 

[Siegfried]

The HS 12 series used a integral cylinder block and head an so was leak proof and possibly stronger than the merlin Allison. Soviet versions used inferior fuel but fuel injection. The Swiss achieved over 1500 in their MS 406 developments. the HS 12Z added 4 valves.

 

[Altea]

Ciao!

...
from 1100 to 1000 hp is ~ 10% (is 10% with base 1000) if the plane got 570 km/h (354 miles) with 1100 hp (metric) under cubic root laws it got almost (because commonly when used for up power was considerd at best so if we go for less power is at badest) 552 km/h (343 miles) with 1000 hp taking in the count the higher altitude of max continues setting it's easy that the speed is bit more.

Ok for higher alt! I forgot about it...

 

[Altea]

The country was politically unstable and quite possibly at the verge of a communist revolution, this is nasty stuff given the atrocities in Spain, the Soviet Union and Hungary. Remember, the Spannish civil war began over Priests and Nuns being murdered since the standard Marxist-Leninist ideology at the time regarded the Church as half their problem.

What I am saying is the country was divided and this reflected on their industrial policy.

I don't remember any atrocities during Tony Blair, François Mitterand or even Leon Blum governement.

The "Front Populaire" as well as spanish "Frente Popular" was a political calition including for most of them respublicans, socialists reformators and other left and centre partys.

In spain communists had no more than 14 MP/278. Maybe 4 of them were Komintern members. The POUM communists were frankly anti-stalinists, it's why their leader was even assassinated by soviet NKVD during spanish civil war, at general shock. Don't see any risk of communist revolution there...

Well before any political crisis, the deplorable state of the industry was not allowing any success of french rearmement plans. Due to mental and technical retardation from french headquarters and plane builders the plan I from 1934 was a failure. Looking at LéO-206 and LéO -257B commanded in 1935 cause no better choices, it was obvious that it was hard for them to leave outmoded but proven techniques, sclerotic ideas.

Well what can we say if reported to the end of 1937 france was still rearming with D-501, D-371 and SPAD-S 510 when I-16 and Messerschmitts were fighting in spain. And Polikarpov I-17 triomphating at Paris aviation salon.

At this condition, considering the full failure from existing and future rearmement plans, the radical-socialist Pierre Cot from Blum Governement made the only clever proposal. Massive deliveries from Soviet Union that could send in one-2 months the mid-30ies one year french military production, in exchange of technology transfer and gold francs, of course...

J'v got no doubt that in 1936-37, I-17 with HS engines and chauvière props, and I-16 with modernised american Cyclones could perform better than D-500, D-371 ans SPAD S 510.

As well as SB-2 against MB-131 or Potez 540.

Or DB-3F for Bloch MB-200, Amiot 131, or Farman 221.

No doubts than hundreds of Tupolevs (even some TB-7 why not, with french help...) and Iliushins massed over french boarder should have been made Hitler thinking twice before invading Tchecoslovakia.

Regards

 

[Altea]

This was theoretical limit. In practice Kurzleistung can be used as long as engine limits (temperatur) is correct, which it was in trials. Of course engine wear will be higher.

If you know any circumstance that prevents use of Kurzleistung for long periods, please let you share.

Why don't you manage yourself to read understand yourself the docs you post?

the A-1, with 1,30 ata manifold pressure for 990 PS output at 0m, and
the Aa, with 1,35 ata manifold pressure for 1045 PS output at 0m, both for cleared for 5 minute periods.

At least from all available speed curves from the E-1/E-3 try to do not choose an aberrant one. The tested old plane had no standard hydro-coupling, and too few points to establish a reliable curve from it.

No, report clearly states it was measured test. Calibration of instruments 21.4.38, actual measurement flights the following day on Haunstetten four-way record track 22.4.38., and Augsburg airfield, pilot flying plane Dr.Wurster etc. All details given.

You should also learn the difference between a wind tunnel calibration from reference laboratory instruments with uncertainlies chain description and a simple conversion IAS/TAS table (even a controled one).

Also French CEAM tests clearly say the Dewo's cooling is insufficent, Me cooling is better. Dewo had to throttle back twice in climb because rising engine temperature.

That's true, first serial D-520 were often suffering quality standards defaults and other teething troubles. Now, making from some cases a general law, is rather abusive.

 

[Altea]

actual losses in BoF give a clear advantage for 109 14:30 (14 109 losses for 30 520 losses, from JoeB old topic, near same proportion like Hurricane)

J'm not sure that those actual losses can allow to make any definite conclusion about D-520 vs Me-109 results. German archives are far from being complete, there are lacking some pages from war diaries and complete account with units diary losses-deliveries balance is not made.

I will advice E de Mombeek books, articles.

Regards