"Aces Falling"

[Waddell]

I recently watched the excellent "Aces Falling" program on McCudden and Mannock. There is a section where Peter Hart talks about McCudden's tactics of flying at 3-4000 ft higher than normal and to pounce on the enemy. He talks about McCudden using his skills as a mechanic to "sort of" supercharge the SE5a that allowed it to fly at this heigher ceiling where oxygen was reduced.

Can someone explain to me what exactly is being referred to here? Was McCudden's plane modified with a supercharger or was he using a particular flying method that increased the amount of oxygen available to the engine?

I hope I'm not missing something here, but as I understand it the SE5a was powered by a normally aspirated V8 Hispano Suiza with a single carburettor?

Gareth?

Scott

[centurion]

The spinner from an LVG CV was fitted to the four blade prop. Elevators were narrow chord and I think some attention was paid to the rigging wires all to reduce drag. The engine was a Peugot built 200hp Hispano Suiza and I believe there was some tinkering with the exhaust. There was also general fine tuning around the carb etc - no super charger though.

[David Filsell]

Placing the carburetter air inlet tubes in a position in which the airflow was forced into them would increase airflow would/could cause a supercharged effect.

[Fovant]

McCudden also mentions that he had high compression pistons fitted to his Hispano engine, which gave it more power and a better rate of climb.

On modern aero engines such as Lycomings, this sort of modification will increase the horsepower by about 10%.

[centurion]

Placing the carburetter air inlet tubes in a position in which the airflow was forced into them would increase airflow would/could cause a supercharged effect.

I have some doubts as this could also significantly reduce the temperature in the carburetor air intake with adverse effects on engine performance (especially at high altitudes). The Hispano Suiza used either the Claudel or Zenith Carburetor and I've seen one report of them suffering from such an effect. I've also seen a suggestion that Guynemer's SPAD had an engine with a larger than usual carburetor, possibly this could be another approach McCudden might have adopted.

BTW having found a photo of the SE5a in question it definitely had a non standard exhaust configuration.

[alex revell]

Yes, McCudden had a set of high compression pistons fitted. The SE5a B4891 had the standard short exhaust pipes.

[centurion]

Yes, McCudden had a set of high compression pistons fitted. The SE5a B4891 had the standard short exhaust pipes.

Which were standard on the SE5 (with the 150 Hp engine) and not the SE5a (apart from one or two early ones with numbers starting with A which probably started on the production line as SE5s). 56 Squadron for some reason had their long exhaust pipes cut short but looking at McCudden's machine the exhaust has a slight outward bend at its end and possibly a slight flare. I don't think that its the standard long pipe cut short. No one seems to know why 56 (and no other squadron) cut their exhaust pipes short - possibly copying McCudden? The fact that McCudden's Hispano Suiza was Peugeot built is also significant. Most early SE5as had either Wolseley or Brasier built engines both which proved unreliable (The Brasier gears and shaft needing replacement by British made spares and the Wolseley being problematic until the Viper version with high compression pistons was introduced in 1918) More reliable Hispano Suiza Engines from other French manufacturers were also introduced in Jan 1918. It looks as if Mc Cudden had aleady managed to wangle an engine from a more reliable French manufacturer.

[David B]

In McCuddens book FLYING FURY he mentions fitting high compression pistons to the Hispano engine because he was

complaining that the Rumpler was every bit as fast as his SE5A over 16000 feet. He mentions that the engine gave more

revs than standard thus the aeroplane could climb faster. At time of 7 minutes to 1000 feet was mentioned.

Thus I really think that the term "supercharging" was used rather loosely when he really meant an increase in power

by using high compression pistons.

David

[Adrian Roberts]

At time of 7 minutes to 1000 feet was mentioned

Presumably this should read 7 minutes to 10000 feet? Seven minutes to 1000 feet is not very impressive at all!

[Waddell]

Thanks all. I'm not sure any explain exactly what Peter Hart is talking about though. In the same commentary he says that McCuddens SE5a had the ability to fly 3-4,000 ft higher, which is a significant increase in ceiling at 20-21,000 feet. The use of the term "sort of" supercharge indicates to me that any modifications he may have carried out increased maximum ceiling, as a supercharger would.

Granted higher compression ratio, decrease in drag, exhaust modifications and finer assembly tolerances (as in the Peugeot engine?) will all create and increase in horsepower and rate of climb. But I'm not sure these will increase the aircrafts ceiling which is what Peter Hart is referring to.

I'm thinking that modifications were more along the lines of the induction and fuel system. These would seem the likely places a mechanic would start.

Anyone know for certain?

Scott.

[David B]

Sorry Adrian, finger trouble, yes 7 minutes to ten thousand feet (10000). I'll have a look through his book again

and see of there is any mention of other modifications that may have been carried out

David

[David B]

The only other modification to his SE5 mentioned in his book was the addition of a Spinner from a L.V.G. which

he shot down at Havrincourt. Apparently this spinner fitted perfectly and he claimed that it made his aircraft 3

mph faster at 10,000 due to the streamlining effect

david

[Dolphin]

Another McCudden modification is mentioned in Christopher Coles's McCudden VC. He had a hole cut in the engine bulkhead and a shutter fitted, so that he was able to open it and allow some heat from the engine to penetrate the cockpit. This might not have made the SE 5a climb higher or faster, but it would have helped to keep the pilot slightly warmer - a significant factor at 20000 feet in an open cockpit.

Gareth

[Waddell]

Thanks David and Gareth. I think P Hart might be referring to all these performance modifications to his plane and maybe his mechanical ability helped him fly the aircraft beyond its ceiling limit. I dare say he had a good feel for the airplane and the extra height would no doubt have helped his dive speed.

Isn't this what the Me109 pilots did in the next round? (not meaning to go off topic!)

Scott.

[centurion]

The only other modification to his SE5 mentioned in his book was the addition of a Spinner from a L.V.G. which

he shot down at Havrincourt. Apparently this spinner fitted perfectly and he claimed that it made his aircraft 3

mph faster at 10,000 due to the streamlining effect

david

Which I'd already mentioned in an earlier post!

[Waddell]

Thanks Centurion.

Just a point of note it seems that Wikipedia reads similar to "aces falling" in the tactics section of James McCudden-

http://en.wikipedia.org/wiki/James_McCudden

They seem to believe that McCudden "effectively supercharged" his SE5a. I'm probably being pedantic, but unless he had a system of forced induction, then this statement is not right. It seems that the truth is that McCudden modified and significantly improved the performance of his aircraft.

Scott.

'

[David Filsell]

Placing carb air intakes to receive better airflow would amount to some increased air induction, but I am not sure what the effect would have been in cold air at altitude. Is it possible, since he fed warm air into the cockpit, that he also fed it to (war) the carb. intakes?

[alex revell]

Regarding the shortened exhaust pipes on 4891. It's important to remember that things were far from standardised in those days and the squadrons in the field made many alterations to their aeroplanes. My memory is that McCudden obtained a set of high compression pistons that were to be fitted to the Viper engine and installed these. Not sure where the information came from that 4891 was powered by a Peugeot made engine, but that may be so. Charles, the 56 Sqdn engineering officer, gave me a breakdown of all the types of engines used in the SE5 and SE5a, which I summarised in my history of the sqadron, High In The Empty Blue. It's rather long but if anyone is interested I will type it out and post it here.

[David B]

How often has Wiki found to be incorrect.

To increase the power of a motor you have to do several things

1. Higher compression pistons - this is a known fact on Mccuddens engine

2. Tune the exhausts, I am not sure whether they knew of this in 1918, in any case most aero engines have short straight thru exhaust pipes

or stubs which I think would not have helped.

3. Better the fuel flow i.e. larger carby or multiply the number of carbs - this was not done I believe

4. Add a supercharger or turbo charger. Were these techniques available on WW1.

By how much did Mccudden increase the power of his engine. I dont know whether he was using 150/200/250 hp motors but

a 10 percent increase would have upped the power by 15/20/25 hp. This would have been quite significant especially if

the power could have been sustained above 16000 feet which is where he complained that he was losing out to the LVG's

David

[centurion]

How often has Wiki found to be incorrect.

To increase the power of a motor you have to do several things

1. Higher compression pistons - this is a known fact on Mccuddens engine

2. Tune the exhausts, I am not sure whether they knew of this in 1918, in any case most aero engines have short straight thru exhaust pipes

or stubs which I think would not have helped. McCudden's aircraft did not have the standard long exhaust fitted to most SE5as so something may have been tried

3. Better the fuel flow i.e. larger carby or multiply the number of carbs - this was not done I believe It was done on some Hispano Suizas fitted to SPADs (see earlier posting) so could have been done to McCuddens SE5a

4. Add a supercharger or turbo charger. Were these techniques available on WW1. Experimental supercharging was being tested but I don't think applied to production aircraft during WW1

By how much did Mccudden increase the power of his engine. I dont know whether he was using 150/200/250 hp motors but

a 10 percent increase would have upped the power by 15/20/25 hp. This would have been quite significant especially if

the power could have been sustained above 16000 feet which is where he complained that he was losing out to the LVG's Rumplers surely

David

Supercharging is one of those terms tossed around quite carelesly. I have seen articles entitled 'how to supercharge your PC' for example but I haven't fitted a blower to mine!

[Waddell]

Supercharging is one of those terms tossed around quite carelesly. I have seen articles entitled 'how to supercharge your PC' for example but I haven't fitted a blower to mine!

I think you might be right Centurion. I've probably read into the comments too literally. Interesting to hear the extent of the modifications regardless. Supercharging in the true sense certainly had its day in the years following the war!

Scott

[phil@basildon]

The supercharger was about during the Great War, the problem with them was it put an enormous strain on the engine itself resulting in engine failure. The best known supercharged engines were probably the "Blower Bentley's" of the 1920's, this was a private enterprise by Wolfe Barnato, at first W.O. would have nothing to do with it and withdrew factory support!

If a supercharger was fitted high compression pistons would not be neccessary as the supercharging effectivly increases the compression ratio, it would be more advisible to reduce the compression ratio to prevent damage to the engine.

The Germans attempted to supercharge the engines of the Zeppelins but they proved so unreliable the idea was dropped.

Turbocharging were an exhaust turbine drives a supercharger proved more effective for high altitudes because there was an element of self adjusting at high altitude but I can find no reference to turbochargers before the mid thirties.

[SiegeGunner]

WW1 coastal motor boats built by Thornycroft were powered by a variety of marinised aero-engines and were capable of about 40 kts. Were they perhaps supercharged?

[phil@basildon]

Supercharging was very unlikely for the reasons I stated in my previouse post. Supercharging puts an enormous strain on any engine, the engines at that time were not strong enough. To fit a low pressure supercharger was not viable as it would require more power to drive it than would be gained. The programme about McCudden seems to have taken everything on Wiki as gospel.

[alex revell]

I don't think the people who produced the programme had any need to consult Wiki.