'Increasing the Charge' - how piston engine technology provided the power to fly

True T, but R-R - oddly enough - didn't include it in the data spec set provided for the 'Flight' article..

& even a fat & fully fuelled Thunderbolt could blow all its juice in under an hour - if Eagle powered..
 
US fighter pilots operating R-2800s were kept busy with flight engineer-type duties..
.. by comparison to FW 190 fliers who had the benefit of the 'Kommandogerat' control automation..

Below - a NACA report appraising the device.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093290.pdf
 
Thinking about fuel consumption as yer do brought back memories of Tizard's 'sprint fighter' able to get up and intercept the Germans before they got to London... a tall order in 1935!
The Crecy came about from that thought piece.
Also looking through the RRHT Crecy book I came across the picture of Napier E.113 a twin cylinder 2-stroke sleeve valve test unit with a junk head. This soon gave trouble with sleeve sealing and supported Rolls move to an open ended sleeve design which the Ministry up to that time had been against, favouring the Junk Head.
The results of E.113 were incorporated into an X-config 24 cyl engine project, cancelled in 1942 as Sabre problems overwhelmed the Napier engineers.
An X-config is not listed in the back of 'By Precision into Power' although E.123 is mentioned as a 4,000hp 2-stroke PI petrol high speed engine. So the Napier X config remains a mystery.
 
Well T, maybe they ran the idea of an X-mill past Frank Halford & he told them not to be so bloody silly..

Are there any examples - anywhere - of a successful service X-type engine?

The engine boys over at D-B turned to a bit of a capacity bump, high comp & fat camming..
.. on their smaller ( but still ~Griffon/Sabre sized) V 12 to get cruise economy & cope with single stage
supercharger/modest boost limitations ( later going to chemical supercharging & ADI too)..

http://www.enginehistory.org/German/daimler-benz.shtml

(Scroll down the linked page for cam data comparisons)..
 
Haven't got time to find which post but somewhere on the site is a growth curve for Merlin and DB engines... off to catch a train south... don't think I'll have time for Kew this time...
 
& here, a 'Flight' article that provides a mid war period - historical overview of supercharging..

.. inc' mention of the RAE developed Napier Lion-turbo that made 32,000ft - a couple of decades previous..

http://www.flightglobal.com/pdfarchive/view/1943/1943%20-%202320.html
 
Yes the RAfactory/RAE started work in 1915 on superchargers under James Ellor; and work continued for the rest of the piston era. They designed 4 types of supercharger including the turbo which was used for both the Liberty 12 and the Lion, so they were RAE turbos mounted on these engines, RAE did both pieces of engineering; the Lion was done also as a gered version and the blower dia was enlarged for turbo test serias 2. ; the turbo part gave all sorts of problems and so most work from 1925 onward was with mechanical; but that did not mean turbos were neglected. A couple of years ago I wrote a series on another bulletin board; if people are interested I can update and repost here.. any thoughts?
I have attached a page from the report and a pretty poor copy of a Fairey Fawn showing the turbine... streamlining caught on a little later in the period!
 

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Thanks T, engine development certainly got ahead of airframes in that period, & even ahead of themselves..
Metallurgy, pressure control & coordination were certainly problematic in early turbo installations.
& big powerful engines too, in themselves..
Viz the Napier Cub, the 1st 1,000hp aero engine - a feat - but with no reasonable prospect of practicable utility..

(& I read your early developments thread - on another site, per previously listed link - & enjoyed it).
 
In this Sabre Tempest recognition film (featuring an early build 486 NZ Sqdn machine),
- the characteristic high rpm capability is clearly apparent, an advantage for high speed fighter flight.

http://www.youtube.com/watch?v=BKq51LdJ-ZU

Jim Sheddan, long serving 486 NZ pilot ( he made C.O.) on Typhoons & Tempests put it thusly..

"Of all the Allied fighters in action in the last 12 months of the war, the Hawker Tempest, powered by a
Napier Sabre sleeve valve engine was in a class of its own.
In the hands of an experienced pilot, it was more than a match for any aircraft flying on either side...
...A Merlin by comparison, was a slow revving motor, cruising revs being in the vicinity of 1,800 rpm
while maximum revs were in the 3,000 range. Thus there was a flat spot between when the pilot asked for
maximum effort...& received it. This time lag could be crucial when bounced by the enemy.
The Napier Sabre, by comparison, cruised at 3,500 rpm & had a maximum of 3,850.
There was so little difference between cruising & flat out that it could be claimed that a Tempest was almost
operating at its maximum performance at all times.
This had an advantage in that it was difficult for enemy fighters to position themselves to bounce..."

& confirmation of this is shown in the interrogation report of a captured LW fighter pilot..
..as listed in the USAAF Air Intel' Summary of 18/3/45..

Re: the Tempest, it "...had superior speed & climbing ability which made it extremely formidable.
The apparently excellent field of vision afforded the Tempest - made it hard to surprise."
 
J.A.W. said:
Viz the Napier Cub, the 1st 1,000hp aero engine - a feat - but with no reasonable prospect of practicable utility..

The Cub was designed into the initial versions of both the entrants (Blackburn and Avro) for the 16/22 heavy torpedo bomber requirement- until somebody realised that an aircraft powered by a single 2,450lb engine with early 1920s reliability flying for long periods over water was a less than ideal prospect.
 
Well, risks - such as flying a Vimy - on long distance over-water routes were undertaken, with little
prospect of maintaining flight in the event of an engine failure..

However, the Cub was an example of the dreaded X-type..

Here, some details from 'Flight'..

http://www.flightglobal.com/pdfarchive/view/1922/1922%20-%200118.html
 
...a pretty poor copy of a Fairey Fawn showing the turbine... streamlining caught on a little later in the period!

Here's the only image of a turbocharged Fairey Fawn I could find, and here's the write-up from Putnam's 'Fairey'...

"The supercharger used was a continuous-flow turbo-compressor with the turbine driven by exhaust pressure through nine nozzles. It was mounted in front of the engine, below the propeller, and this position necessitated the use of the earlier type of side or lateral radiators. One of the first changes which had to be made was the replacement of these with a special underslung radiator with adjustable shutters. The RAE tests started in March 1925 and continued for about three years. Development was hampered by engine and blower failures and by the time taken to make the necessary modifications — including, for instance, an increase of internal clearances in the blower to prevent seizures with the changes of temperature on climb and glide, the raising of the engine compression ratio and the fitting of a bigger-capacity water-pump. In the end, after considerable labours, times-to-height and rates-of-climb were showing useful improvements on the standard figures in spite of the additional weight and drag of the installations, and level speeds were also slightly better. But. even with these improved results, it was concluded that the gains in climb and ceiling were not enough to outweigh (at least with the Fawn) the performance losses near the ground because of the power absorbed by the blower and because of the propeller pitch-angle which had to be used to obtain the better performance at altitude."


cheers,
Robin.
 

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Robunos (Robin),
Thanks for that... adds to our pool of useful knowledge. When I've collated the test results I'll post a bit more performance data.
 
And here's the Gloster Guan, also powered by a turbo-charged Napier Lion, from Putnam's 'Gloster'.

"The Guan was an experimental single-seat high-altitude fighter built to flight test supercharged aero-engines. Similar in construction and appear ance to the earlier Gorcock, the Guan had an all-metal fuselage and wooden wings of the Gloster H.L.B. combination, which spanned 3 ft 4 in more than the Gorcock with a 48 sq ft increase in wing area. It was Folland’s intention to combine in one aircraft the Gorcock’s high top speed, which was nearly 30 mph faster than contemporary Service fighters, with a substantial improvement in service ceiling and this he achieved. Three Guans, costing £7,500 each, were ordered by the Air Ministry early in I925 and design work began in February. The first aircraft, J7722, was powered by a 450 hp Napier Lion IV engine fitted with an exhaust- driven turbo-supercharger mounted externally under the propeller shaft. This position for the supercharger resulted in a prominent array of external ‘plumbing’ which was a feature of the Guan. Completed in June 1926, J7722 was delivered to the RAE Farnborough in August. The second Guan, J7723, was powered by a 525 hp direct-drive Lion VI, also fitted with an exhaust-driven turbo-supercharger which was mounted on top of the cowling above the propeller shaft. This aircraft was completed early in 1927 and was delivered to Farnborough. Although the supercharging enabled maximum power to be matintained up to 15,000 ft, at which height the Guan had a top speed of 175 mph, and the service ceiling was pushed up to 31,000 ft, the turbo-superchargers were a continual source of trouble. The engine manufacturers made a number of modifications to the units and the system, but very little improvement was achieved and the development was abandoned. This failure led to the cancellation of the third Guan which was to have been powered by the inverted, geared Napier Lioness engine similarly supercharged. Before the programme was finally terminated, J7722 was fitted with a Hele-Shaw Beacham constant-speed variable-pitch propeller."


cheers,
Robin.
 

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J.A.W., thanks, interesting video to hear the sound of a sabre.
 
Basil said:
J.A.W., thanks, interesting video to hear the sound of a sabre.

You are welcome B, there is something quite musical about the sound of an even firing 120` triple arrangement..

& Kermit Weeks intends to have a Sabre Tempest in airworthy order again..
 
The final generation of piston powered fighters present an interesting contrast.
Here are the speeds attained at sea-level by the top performers.
(IMO this provides a fair indication of the ever-sought balance - between engine out-put & aero-slick airframe)..

399mph Grumman F8-F2 Bearcat;
399mph Vought R-4360 Corsair;
400mph Vought F4U-5 Corsair;
406mph Hawker Centaurus Sea Fury;
408mph V-S Griffon 101 Spiteful F XVI;
412mph N.A.A. Merlin-9 Mustang P-51H;
418mph Hawker Sabre 7 Tempest F 6;
419mph Hawker Sabre 7 Fury F 1..

US figures are from 'Standard Aircraft Characteristics'..
- & British are from Boscombe Down/'Flight' archive..
 
J.A.W. said:
The final generation of piston powered fighters present an interesting contrast.
Here are the speeds attained at sea-level by the top performers.
(IMO this provides a fair indication of the ever-sought balance - between engine out-put & aero-slick airframe)..

399mph Grumman F8-F2 Bearcat;
399mph Vought R-4360 Corsair;
400mph Vought F4U-5 Corsair;
406mph Hawker Centaurus Sea Fury;
408mph V-S Griffon 101 Spiteful F XVI;
412mph N.A.A. Merlin-9 Mustang P-51H;
418mph Hawker Sabre 7 Tempest F 6;
419mph Hawker Sabre 7 Fury F 1..

US figures are from 'Standard Aircraft Characteristics'..
- & British are from Boscombe Down/'Flight' archive..


There's less than 5% separating top from bottom, which says to me there is no effective difference between the performance of any of them.
 
Good to see some interest input-wise on the thread from the 'Poobah'..

Quite close indeed, in fact about as close as the closing/evading speeds of FW 190 JABOs attacking Blighty..
& then evading flat out.. & the Spitfires (too slow) & Typhoons (speed in hand) tasked with chasing them down..

- Or running down V1s going the other way across the channel on a heading for London..

If a cyclist swishes close by you while out strolling - with a + 20mph speed - does it seem significant?

Or try telling that to the copper in an unmarked patrol car you've just passed by at +20mph..
- over the limit - once s/he's pulled you over..
 
Isn't that comparing apples and oranges ?

20 mph:

- Quite the limit for an untrained cyclist : 100 %
- In the mentioning speedin case, it's about 25 to 30 % above speed limit,
depending on the country
- In the case of the mentioned aircraft, it's less, than the differences for the max.
speed to be found in different sources.
 
Reading, for example, the Decisive Duel, highlights how matching or exceeding, if only by 5mph, the speed of your opponent enables you to catch or escape in the right circumstance. if you are jumped then characteristics other than speed in a straight line counts... what this has to do with engine technology I am not sure. I suggest fighter strategy and tactics goes into another thread and we revert to engineering the difference in this thread.
 
Well T, 'power to fly = power to speed', & aero-engine designers sought to find the best balance..
Power/weight, frontal area, cooling technicalities, prop disc accommodation, & etc.

For fighters, engine characteristics ought to be different? Yet often bomber engines were employed..

Oddly - in the case of the FW 190, the original BMW radial was replaced with a Jumo V12, & improved..

& US fighters drew criticism for not optimising coordinated power controls for the pilot,
but the US didn't seem to take note until the Merlin & FW 190 showed them what difference it made.
 
& T, are you able to elucidate on the reasoning behind R-R's engine team to reverse the Griffon crank rotation?

The 'unintended consequences' impact on Spitfire pilots was dire in more than a few instances..
Was it a packaging thing, or were balance/harmonics involved, hence the firing order change too?
 
There was much work on the 1930s to standardise as much as possible to make wartime production across the nation as simple as possible; shadow factories were part of this; The direction of rotation on the Griffon was the result of the Society of British Constructors deciding in the late 1930s to standardise the direction of rotation as clockwise when viewed from the pilot's seat. All new engines would adopt this from then on... this actually meant only RR had to change.
 
Thanks T, & so the tens of thousands of Merlins built, - in fact outnumbered all the later 'standardised' types
- yet were not required to adhere to the same 'standard'..

Yet R-R did devise 'handed' Merlins for the D-H Hornet sans too much difficulty..
( Did the Twin Mustang use the same R-R set-up - or was the Packard Merlin 'handed' discretely?).

Took a good while to fit the 'standard' fighter instrument panel, & longer yet to tidy up the 'dogs breakfast' of control placements.. ..or even introduce pre-flight check lists, all these must've been costly in non combat losses..
 
Jemiba said:
Isn't that comparing apples and oranges ?

20 mph:

- Quite the limit for an untrained cyclist : 100 %
- In the mentioning speedin case, it's about 25 to 30 % above speed limit,
depending on the country
- In the case of the mentioned aircraft, it's less, than the differences for the max.
speed to be found in different sources.


No, since it is the speed relative to the observer..
..even if you were travelling at 300,000mph in space & another ship passed close by overtaking at 300,020mph
- & moving away - it would be seen moving at an appreciably faster rate - relative to you..
 
As the convention was for new designs the Merlin was not subject to 'the rule'; but the Griffon I onward was; curious what happens to 'national' standards... still happens, of course.
The Twin Mustang story goes something like this
The XP-82 was to be powered by two Packard-built Rolls-Royce V-1650 Merlin engines. Initially, the left engine was a V-1650-23 with a gear reduction box to allow the left propeller to turn opposite to the right propeller, which was driven by the more conventional V-1650-25. In this arrangement both propellers would turn upward as they approached the center wing, which in theory would have allowed better single-engine control. This proved not to be the case when the aircraft refused to become airborne during its first flight attempt. After a month of work North American engineers finally discovered that rotating the propellers to meet in the center on their upward turn created sufficient drag to cancel out all lift from the center wing section, one quarter of the aircraft's total wing surface area. The engines and propellers were then exchanged, with their rotation meeting on the downward turn, and the problem was fully solved. The first XP-82 prototype (44-83886) was completed on 25 May 1945, and made the type's first successful flight on 26 June 1945. This aircraft was accepted by the Army Air Forces on 30 August 1945, whose officials were so impressed by the aircraft, while still in development, that they ordered the first production P-82Bs in March 1945, fully three months before its first flight.... but then they decided to go to Allison for a less powerful but all-American engine. The 80-odd Merlin P-82Bs were assigned to training and for the first time the Trainee pilots found they had a trainer with more performance than the operational model!
This ref may be of interest.
 
Cheers for that T,

The Twin Mustang/Do 335/D-H Hornet/Tigercat all present interesting attempts at fast/last piston twins..

AFAIR, the USAAF considered the USN R-2800 powered Tigercat - even getting one to test,
- & although they got a Do 335 (& Meteor) too, I don't know if they ever got a Hornet..

Likewise, the Brits got an F-7F for evaluation, but no P-82..
Two Merlins = Too similar?

Both NAA & USAAF were reportedly irritated by having to accept the Allison-virtually a 'shotgun marriage'
- said to be via the political influence of a prominent GM shareholder within the Truman administration..
 
The P&W R-2800 was capable of significant performance increments over its progressive development.
A good part of this was its capability of accepting increased boost levels , even if for time periods that were,
as LJKS put it.. "ephemeral", & were dependant on high test fuel plus ADI...

The P-47M, a late Thunderbolt development that was initially touted as a U.S. V1 interceptor
(but proved both too late & anyway - too slow - at low altitudes) was run at supercharger boost levels in
excess of 70" Hg (+20lb) , & provided excellent high altitude performance for the last 8th AF air superiority
unit flying them, the 56th FG, - but not without engine issues.. ..like a TBO of 15-30hrs.. ..see this link below..

http://www.wwiiaircraftperformance.org/p-47/p-47m-20march45.jpg
 
This 'Flight' article has a chart showing the power at altitude characteristics of the R-R Griffon 3-speed/2-stage 100 series V12.

http://www.flightglobal.com/pdfarchive/view/1946/1946%20-%200062.html
 
If you use the search function you will find we already have a thread on that:
http://www.secretprojects.co.uk/forum/index.php/topic,13990.0.html
 
JFC Fuller said:
If you use the search function you will find we already have a thread on that:
http://www.secretprojects.co.uk/forum/index.php/topic,13990.0.html


Thanks for posting the link to the dedicated Griffon thread JFCF..
.. however, as an alternative development to the turbocharger method of maintaining induction charge/power to fly for the piston engine at increasing altitude - it does belong here too..
 
tartle said:
As the convention was for new designs the Merlin was not subject to 'the rule'; but the Griffon I onward was; curious what happens to 'national' standards... still happens, of course.
The Twin Mustang story goes something like this
The XP-82 was to be powered by two Packard-built Rolls-Royce V-1650 Merlin engines. Initially, the left engine was a V-1650-23 with a gear reduction box to allow the left propeller to turn opposite to the right propeller, which was driven by the more conventional V-1650-25. In this arrangement both propellers would turn upward as they approached the center wing, which in theory would have allowed better single-engine control. This proved not to be the case when the aircraft refused to become airborne during its first flight attempt. After a month of work North American engineers finally discovered that rotating the propellers to meet in the center on their upward turn created sufficient drag to cancel out all lift from the center wing section, one quarter of the aircraft's total wing surface area. The engines and propellers were then exchanged, with their rotation meeting on the downward turn, and the problem was fully solved. The first XP-82 prototype (44-83886) was completed on 25 May 1945, and made the type's first successful flight on 26 June 1945. This aircraft was accepted by the Army Air Forces on 30 August 1945, whose officials were so impressed by the aircraft, while still in development, that they ordered the first production P-82Bs in March 1945, fully three months before its first flight.... but then they decided to go to Allison for a less powerful but all-American engine. The 80-odd Merlin P-82Bs were assigned to training and for the first time the Trainee pilots found they had a trainer with more performance than the operational model!
This ref may be of interest.



T, further to your Merlin twin directional rotation factor.. ..here is a 'Flight' article that shows that the Hornet
rotated opposite to the P-38 (& revised P-82).. oddly enough..

http://www.flightglobal.com/pdfarchive/view/1947/1947%20-%200004.html
 
J.A.W. said:
T, further to your Merlin twin directional rotation factor.. ..here is a 'Flight' article that shows that the Hornet
rotated opposite to the P-38 (& revised P-82).. oddly enough..

Good point, maybe the fuselage of the Hornet acted as a kind of end plate for the center wing, missing in
the F-82 ?
 

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As the Hornet was intended for carrier operations too, it was designed to have a reversed rotation of one of its propellers to counteract torque effects. This was done by inserting an idler wheel in the reduction gear of one of the engines. Initial operation showed it tended to overheat at the tooth contact... very serious. Special injection jets were introduced to ensure there was an oil film on the contacting surfaces of the gear teeth. There was also some rearrangement of 'accessories' e.g moving water pump from bottom of the wheelcase to the side of the crankcase where it was driven by a drive originally intended for a generator. Result a very low drag engine nacelle.
 
Jemiba said:
J.A.W. said:
T, further to your Merlin twin directional rotation factor.. ..here is a 'Flight' article that shows that the Hornet
rotated opposite to the P-38 (& revised P-82).. oddly enough..

Good point, maybe the fuselage of the Hornet acted as a kind of end plate for the center wing, missing in
the F-82 ?



My thoughts exactly J, it does appear that the NAA P-82 team picked up the Hornet Merlin rotation with
the 'handed' R-R mills - only to find that the earlier P-38 rotation orientation was in fact necessary..

The 'handed' Allison V-1710s did not use the R-R gearing solution for reversing prop rotation - but spun the crank
in opposite rotation - like the Griffon..
 
This 'Flight' article on the civil Centaurus includes a power ratings @ altitude graph..

http://www.flightglobal.com/pdfarchive/view/1949/1949%20-%201484.html
 
This period German document shows the enhanced boost levels applicable for DB 605 V12 mills..
.. when high-test C 3 fuel was available over B 4 type, raised from 1.8 ata to 1.98 ata..

http://www.kurfurst.org/Engine/Boostclearances/DB_Niederschrift6730_DB605DBDC_20-1-45.pdf
 
Not sure, that it really shows, how the boost level of the DB 605 could be increased.
To my opinion, this report rather is about, how boost level (and power output !) had to
be decreased, because of low fuel quality !
The change to C3 was principally rejected in that paper, as final testing still wasn't finished.
Testing of four engines with boostlevel set to 1.98 ata brought negative results (no further
explanation, judging further text probably thermal loads became a problem), operational use
was only allowed for a single fighter group and maybe for single recce aircraft, but not fleet
wide.
Nevertheless an interesting paper, one of the last paragraphs mentions a planned comparison
of the Me 109 and the Mustang, and although no flights were conducted, the comparison of the
overall quality is said to have brought devastating results.
 
More on the Hornet installation:
The DH 103 Hornet, as one of the smallest twin-motor aeroplanes in the world, presented quite a problem in accommodating its power plants in the airframe.
To meet the problem, the supercharger air intake was extensively modified and the 130 and 131 were the first Merlins to incorporate down-draught induction systems. To eliminate the air scoop as used on the Mosquito, ducted air intakes were faired into the leading edges of the wings. The coolant pump was also moved from the bottom of the motor to its starboard side, and these modifications resulted in a bottom cowling line free from excrescences and of symmetrical form-an ideal arrangement for a high-performance fighter.
The engines were mounted low to obtain a smooth airflow over the wing, exhaust ejection below the wing, a short chassis leg below the nacelle for easy stowage when retracted, and the best possible pilot's view.
Propellers rising inboard were tried first as being preferable for fore-and-aft stability, but they blanketed the rudder at low speeds and rendered it ineffective for correcting swing on the ground. Propellers rising outboard were therefore adopted and the stability standards secured by tail plane dimensions and stability weights.
So not just the Twin-Mustang had to swap handed engines side to side.
[info from here which also discusses the Peregrine installation in Whirlwind]
Also attached is the Mossie nacelle for comparison.
 

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