mercredi 29 février 2012

Nieuport 161 and Morane 405 - Learning from planes crashes... or not... (revised 09 / 22 / 2014)

What kind of engine was fitted in the Nieuport 161 - 02?

At first, I need to go back about the Nieuport 161 to give a more comprehensive picture of this fighter.

The top speed I computed for this fighter - from 485 to 490 kph (see my previous post here) was based on papers publishing that the engine fitted on her (prototype #02, flying since September 1937) was an Hispano-Suiza 12 Ycrs providing 860 hp at 3,150 m, inducing that the best performance would be reached at about 4,500 m ASL.

It’s true, however, than the Morane-Saulnier MS 405-02, which flew a bit earlier in 1937, used a 920 Cv engine allowing her to reach 483 kph at 5,000 m (this engine was a prototype of the 12 Y 29). 

It is the only credible French measure for the Morane 405 (given by G. Botquin in l'épopée du Morane 406, le Fanatique de l'Aviation, #100, p. 31, 1978) before the one obtained by the MS 405 #12, fitted with the 12 Y 45 engine and reaching 493 kph.

If the same HS 12 Y 29 engine have been fitted on the Nieuport 161, the engine providing its maximum output 350 m higher than the 12 Ycrs, the top speed must be reached, at least, at an altitude of 5,000 m, 1,000 m higher than the speed of 478 kph at 4,000 m published. 
Indeed, the speed increment would be more than 20 kph, pushing the top speed over the 500 kph threshold. 

The difference of 17 km/h with the Morane-Saulnier 405-02 / 406 would have been less important but always significant.

However, the climbing performances of the N 161 will stay better than those of the MS 406. 

Regarding the Morane, the only credible climbing value was the one given by the CEAM who experimented the Bloch 152 fighter against the MS 405 #13 in December 1939 and reported the Morane, with her HS 12 Y 51 engine providing 1,000 hp, climbed to 4,000 m in 5’11” and to 8,000 m in 13’12”.

The last published climbing performance of the Nieuport 161 was 8’22” to reach 6,000 m, an average speed of 11.95 m/s (very near from 12 m/s) from sea level.

The climbing speed measured by Finnish pilots flying MS 406/410 was 5’30” for 3000 m and 10’00” for ,5000 m ( . 

The very better Mörkö Morane, fitted with a Klimov M 105 P (1,050 hp at 4,000 m) needed 8’00” to climb to 5,000 m, giving a average ratio of 10.4 m/s.

Indeed, it was impossible for the MS 406 to climb to 4,000 m in significantly less than 7’.

The CEMA didn't spare Nieuport

From the other hand, fitting the up to date Hispano-Suiza 12 Y 29 on the Nieuport 161-02 was completely unlikely. 

The Morane 406, being ordered, was tightly “protected” by the State services very influential deciders. 

The managers of the Hispano-Suiza company never had another choice: The best engines must be provided to the chosen standard fighter.  

An illustration of this policy might be found in the 1938 fighter program: These wanted completely new planes which must fly faster than 560 kph. 

The first plane to fly was the D.520-01 with a 12 Y 29 engine (920 Cv at 3,600 m ==> 527 kph at 5,000 m).

The second was the CAO 200-01 with a 12 Y 31 engine (860 hp at 3,150 m ==> 535 kph without exhaust pipes and 552 kph with that device).

The third was the Morane 450 with a 12 Y 51 engine (1,000 hp at 3,150 m -> 560 kph). 

The fourth was the Arsenal VG 33-01 with a 12 Y 31 engine (860 hp at 3,150 m –> 558 kph with that device)

Clearly, the Morane company was favored and the SNCAO (ex Nieuport) was not favored at all. 

With the same 1,000 hp engine, the very advanced CAO 200 could reach 595 kph, matching clearly with the Bf 109 F and the Spitfire V fighters.

Another argument reinforcing the previous one, is the one engineer Louis Bonte, the most influential decider who favored unduly the Morane 406, told us in his book “Histoire des Essais en Vol, Docavia #3, 1974". 

He wrote that the first of these Nieuport fighters family, the 160, fitted with an Hispano 12X engine providing 690 hp, met barely the specifications of the program. 

In the site, you can read a confirmation of that : The top speed of the Nieuport 160 was 440 kph, which is consistent with a top speed close to 500 kph with the 860 hp.

The second Nieuport 161 accident

Another point I must discuss is the second accident occurred to the Nieuport 161-02 in January 1938. 

It happened during trials for extra short landings, needed to satisfy the French Air administration. 

Such trials imply to fly at slow speed, while the stall is imminent. 
In such case of flight, both the pilot and the plane are at risk. 
You are flying at high angle, the forward view is very poor, so you don’t  have a good perception of the situation. 

The rudder becomes the safer command because each excessive action on the ailerons will trigger a spin, at very low altitude: No comment!

Obviously, you have few choices to correct any error or any sudden change of the wind speed. 
A lot of accidents are the consequences of such flights at slow speed. 

For myself, I remember it was a terrific experiment – with my very quiet instructor and a very maneuverable and safe Morane Rallye - but I’ve never wanted to repeat it.

In the France of 1938, the rules, decreed in 1934, just before the generalization of the retractable undercarriage and of streamlined fighter planes, were common for all airplanes, all of them must satisfy exactly the same performances. 

For the landing, it was requested a maximum distance of 450 m after passing a 8 m virtual “tree”, with a wind speed slower than 2.5 m/s. 

Obviously, such a trial was easy for all the old slow biplanes, but was much more difficult for very clean fighters, as that was perfectly illustrated by the Nieuport 161. 

It may be added that the Nieuport fighter had a large span for its wings (11 m), with an aspect ratio of 8 (the MS 406 wings had 6.63). So the ground effect was very powerful.

Interesting data on this subject are found during the trials of 3 configurations of the Spitfire Mk I.

With the fixed pitch wooden air screw, the Spit needed 725 m to stop after a 15 m obstacle: this distance fell to 200 m with the Rotol constant speed air screw (and also with a 500 lb lighter plane than the operational ones).

The French test pilot Fernand Lefèvre, tired or embarrassed by another plane, crashed the Nieuport without injuries (and the fighter was able to be repaired but the deciders did not want).

This incident was especially used together with the first crash of September 1936 to vilified the Nieuport 161. 

But another plane suffered from a similar crash during the same test: A Caudron Simoun, which was, also, a very clean aircraft.   

Two of the men imposing these tests had left - 40 years later - a mocking description of these two crashes, demonstrating how they were arrogant and irresponsible (Histoire des Essais en Vol, Docavia #3, 1974). 

I cannot blame the pilot lefèvre, because flying at slow speed is like a random game.

Nevertheless, using the same rules for ultra light slow planes (e.g. Piper J3) and for fighter flying more than 3 times faster was awkward, and the deciders demonstrated a complete lack of common sense, because any routine test would never be the cause of accident.

The Morane, also, suffered 2 accidents!

The Morane 405, also, suffered 2 accidents, just a bit later, unfortunately for the French Armies. 

The first accident occurred on the landing of the Lithuanian pilot Capt. Mikenas, written off the MS 405-01: For 2 sources, he died but, for a more recent source, he was only injured
As usual, it was said that the pilot was responsible.

The second accident occurred during an attempt to reach the ceiling of the prototype MS 405-02 by the Morane test pilot Mr. Ribière

In the August 5, 1937, in the aeronautic review Les Ailes (= The Wings), it was reported that the July 28, Ribière was testing the ceiling of the Morane 405-02, taking off from Villacoublay.
After half-an-hour of climbing, the witness had seen the Morane diving almost vertically at vertiginous speed, hitting the ground and exploding in fire.

It was written "the fighter design was in no way the origin of this crash"

They described the graphical barometric record, displaying a regular climbing interrupted suddenly by a vertical dive until the ground level. 
No pilot action was detected, so the crash was attributed to a fainting fit of the pilot occurring during the climbing.

It was claimed the supply oxygen device was thoroughly tested.

Nevertheless, such a crash may be easily related to the poor climbing ability of the Morane fighter, which was confirmed in the French handbook for the Curtiss P 36 A 1 (chapter I, end of the section entitled procédés de combat): There, you can read that, if the Curtiss climbed to 7,000 m in 11 minutes, the Morane 406 needed 18 minutes to reach the same altitude

This fighter being able to reach 5,000 m in 10 minutes (each 1,000 m step in an average time of 2 minutes), she needed an average time of 4 minutes to climb each new step.

So, the 8,000 m needed at least 24 minutes and a supplementary 1,000 m altitude step exceeded easily 35 to 40 minutes. 

That may be seen as a sufficiently long time for the freezing of some parts of the oxygen supply device.

I've read an interview of Michel Détroyat where he claimed the fighters will have no reason to fly at very high altitude, because that was very uncomfortable. 

So, we know why the test pilots of the MS 406 never flew at high altitude.

Otherwise they could have identified the freezing of the weapons and the oxygen problem. It could had helped to save many pilot’s life during the War...

So, it's logically impossible to accept the design of the Morane-Saulnier fighter was no responsible of the Ribière's crash!

And a bad climbing ability was a good motive to reject this fighter (as all other bad climber ones).

As you have understood, the Nieuport 161 demonstrated her ability to fly up to 11,250 m, where she reached a 328 kph speed. 

This was expected from a plane designed by a company which had got several times the world record of altitude and was accustomed to elaborate efficient fighting planes. 

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