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

[J.A.W.]

I apologize for a quick digression from the fascinating discussion -
Tartle, the pics you posted are from Spitfire: the history (I presume). It looks like a worthwhile book to get.
I searched the book and Amazon gives a frightening price of $336 for a 2001 edition. There is also a more reasonably priced 1984 edition. Does anyone know if the 2001 edition differs significantly? Thanks!

T, have you perused both editions ( 1984 & 2001) - or know of significant differences -as mentioned by A-F?

I would also be interested, but not at $336!, .. s'pose I could try a library inter-loan request though..

 

[Orionblamblam]

I would also be interested, but not at $336!, .. s'pose I could try a library inter-loan request though..

abebooks.com has an '87 for $58, an '87 for $71, an '01 for $104, an '88 for $109. On up to over $400.

 

[J.A.W.]

Much obliged, Obb.

The enduring fame/popularity of the Spitfire clearly at work, there.. eh?

 

[tartle]

What is a book worth? Depends on the individual need. I would love to have 'Spitfire: The History' 2nd edition by morgan and Shacklady as the technical bible; but I live without it, borrowing it through inter-library lending. having purchased ' The Spitfire Story' by Dr Alfred Price as an affordable alternative, supplemented by Ken Delve's 'The Story of the Spitfire: an operational and combat history' (also needed if you buy M&S) and then 'Decisive Duel' to fill in gaps... if following an individual aeroplane I use this site instead of M&S then its off to Kew to expand the information....... as I said " you pay the money when you makes a choice" or as Coldplay wrote in 'Fix You'
"When you try your best, but you don't succeed
When you get what you want, but not what you need
When you feel so tired, but you can't sleep
Stuck in reverse"
Hope this ramble helps.... none of the books gave me 'what I need' but certainly 'what I want(ed at that moment in my researches)' which is information that tells the story of an individual Merlin Mk XX, 45 and 66 engine a colleague has had restored plus his replica Spitfire Vb; oh and a Griffon and Sabre..etc.
Hope this helps?!

 

[J.A.W.]

Thanks - yes, T.

I find A. Price to be an openly partisan Spitfire fan however, which tends to cloud the veracity of his stuff..

Mind you, Len Setright is an unabashed/passionate Napier fan like-wise..

& David Isby has kindly made many of his interesting source documents available - on his site.

http://www.SpitfirevsBf109.com

 

[AeroFranz]

Thanks for the comments, T, and thanks to OBB for the link to abebooks. I am more interested in technical diagrams than operational history and where each individual airframe ended up, but it seems like the book has both.

 

[Orionblamblam]

The enduring fame/popularity of the Spitfire clearly at work, there.. eh?

Lots of books become insanely expensive after they're out of print. Sometimes it makes sense, but often it almost seems more like some sort of money laundering enterprise. I've seen the *same* book available for sale for nearly ten years for the same ridiculously high price, but available elsewhere in some numbers at a fraction of the price. Shrug.

 

[J.A.W.]

Well I never.. ..sounds plausible though, esp' if the same book stays on 'sale' at a ludicrous price..

Now, if they are being bought at those prices, I 'd best check my home contents insurance values..

 

[tartle]

AeroFranz.... Try this book if you are diagramish... J A W why don't you write your own book on 'where are they now the based on the list here.
Now I suggest we tack back to the real meaning of 'increasing the charge' and go here if we want to discuss book pricing, value etc.

 

[J.A.W.]

Where they are now, T?

Burma wasn't it?
Plenty of 'boost' involved with that set-up..

Mind you, a scan of the Nile riverbed off the jetty at Khartoum..
.. where the surplus Sabres were dumped - after the Tempest F6 tropical trials could be worth a try..

 

[J.A.W.]

Stanley Hooker reckoned that.. 4-strokes = 1 stroke for power & 3 to wear the engine out..

So a big 2-stroke article..

http://www.autospeed.com/cms/article.html?&title=Napier-Nomad&A=112994

& a small 2-stroke article, but it too applies to flight power..

http://www.hirth-motoren.de/en/2-stroke-logic.html

 

[LowObservable]

Nice article. If only there was an operational requirement today for a JP-5-burning, ultra-efficient engine that could be scaled down to <500 shp...

 

[J.A.W.]

Yes, L-O, & a pity it aint done - perhaps due to US product liability issues?

& for a more conservative viewpoint..

http://www.epi-eng.com/piston_engine_technology/engine_technology_contents.htm

 

[CJGibson]

For a more light-hearted, but very informative, work on engines, try the pre-Bond villain Robbie Coltrane.

http://www.youtube.com/watch?v=vB0TK0Gdmh4

The supercharger episode is superb.

http://www.youtube.com/watch?v=gwU3bfaLhJ4


Chris

 

[tartle]

Really good book with the tv series... will buy my grandson a copy when he can read!

 

[J.A.W.]

ADI/MW-50 article..

http://www.autospeed.com/cms/A_110213/article.html

 

[tartle]

JAW... great find!

 

[J.A.W.]

Ta, T.

& for a mechanically contrived coordinated engine/prop control system..

- BMW 'Kommandogerat', or how to reduce some of the workload of a radial fighter engine for a sole operator.

http://www.focke-wulf190.com/images/bmwkommandogeraet.jpg

 

[J.A.W.]

This running example of a Continental IV 1430 'Hyper' mill seems to tolerate a bit of 'blipping'..

http://www.youtube.com/watch?v=Jksv4k9n_VU

 

[J.A.W.]

An article for those interested in engine firing orders..

http://www.enginehistory.org/fo/FO.shtml

 

[CJGibson]

Tartle / JAW,

What effects, if any, do cross-over exhausts have and do they have any advantage (improved power, improved efficiency) or are they detrimental to performance. They were fitted to the Merlins on Canadair North Stars for noise reasons, but I wondered what difference they made to the engine operation.

Thanks

Chris

 

[J.A.W.]

CJG, if you refer to posts #10/11 in this thread - you will see a high-speed thrust ejector exhaust.

Any variation on this scheme ( unless as a dedicated alternative thrust-use system such as a turbo)
would be less efficient, power-wise.

However, as you noted, there may be other priorities, viz - noise abatement, or flame damping.

These set-ups invariably reduced available jet thrust - but were deemed needful for operational reasons.

 

[J.A.W.]

Bill Gunston wrote a comprehensive Napier Nomad article for 'Flight'.

Note the SFC efficiency as graphed..

http://www.flightglobal.com/pdfarchive/view/1954/1954%20-%201222.html

 

[tartle]

see also our site here and thread here.

 

[J.A.W.]

Here's a novel piston-power flight application..

http://www.pattakon.com/pattakonFly.htm

 

[tartle]

In 1940-41 the high altitude Wellington was being developed... it was to be capable of flying at 40,000 ft with a significant bombload. Original planning called for 2 turbosupercharged Hercules VIII; but RR were asked to work on a back-up version of Merlin-the 60 series- with 2 stage supercharger... mechanically driven... RR did the performance maths and risk assessment of using a turbocharger and decided not to embark on a development programme for another technology (war raging, BoB etc.).
In 1941 Whittle and bone wrote a paper suggesting the use of a scaled 'Gyrone' engine as a special form of supercharger where two Merlins were supplied with air from the 'Gyrone' compressor... the Merlins' exhaust was then ducted back to the combustion chambers and additional fuel burned to supply energy for the turbine. Any excess energy could then be discharged to generate thrust. First reading of paper indicates that:
A Wellington so equipped was calculated to have a speed of 341 mph at 37,000 ft vs the 'conventional' Merlin powered high altitude Wellie that travelled at 271 mph at its service ceiling of 31,000 ft. This and other work ( RAE sponsored work at Bristol/Fraser and Chalmers; RR and Brown-Boveri unearthed) no doubt informed the creation of an OR for the Napier E145 Nomad which was of similar arrangement... but the engines were 'squashed into one!
Sketch of arrangement attached. Project not proceeded with. The Wellington was superseded by the Mosquito and the resources for Gyrone were directed at getting a working gas turbine for the Meteor etc.
(intriguing what can be unearthed over a day at Kew, some other stuff to follow)

 

[tartle]

When looking at engines it is worth thinking what limits the engine life... there are quite a few things of course limit mechanical reliability but a crude measure is mean piston speed.... defined (imperial units) as MPS= RPM*S/6 ft/min..... S is stroke in inches.
The limit for a service aero engine is 3000 if reliability is to be maintained with good TBO. The RR 'R' engine had an MPS of 3500 and could be relied on to run for 1 hour. Merlin, Griffon and Crecy were all below 3025. Sabre was 3000 to 3166. Industry accepted figure for max reliable MPS is 3000. It would be worth a detailed look at the individual parameters of Sabre vs Merlin, say, to get a feel for what problems were built-in and what were due to lack of development before production. GP cars tend to 3400 MPS.
The RR Eagle II which we discussed in detail elsewhere on this site had a MPS of 2990 which shows how RR's service experience was built in to the initial design of the engine which some people assume to be a copy of sabre but was designed before RR had access to Napier's design... the OR was to develop a similar configuration of greater power.

 

[J.A.W.]

In 1940-41 the high altitude Wellington was being developed... it was to be capable of flying at 40,000 ft with a significant bombload. Original planning called for 2 turbosupercharged Hercules VIII; but RR were asked to work on a back-up version of Merlin-the 60 series- with 2 stage supercharger... mechanically driven... RR did the performance maths and risk assessment of using a turbocharger and decided not to embark on a development programme for another technology (war raging, BoB etc.).
In 1941 Whittle and bone wrote a paper suggesting the use of a scaled 'Gyrone' engine as a special form of supercharger where two Merlins were supplied with air from the 'Gyrone' compressor... the Merlins' exhaust was then ducted back to the combustion chambers and additional fuel burned to supply energy for the turbine. Any excess energy could then be discharged to generate thrust. First reading of paper indicates that:
A Wellington so equipped was calculated to have a speed of 341 mph at 37,000 ft vs the 'conventional' Merlin powered high altitude Wellie that travelled at 271 mph at its service ceiling of 31,000 ft. This and other work ( RAE sponsored work at Bristol/Fraser and Chalmers; RR and Brown-Boveri unearthed) no doubt informed the creation of an OR for the Napier E145 Nomad which was of similar arrangement... but the engines were 'squashed into one!
Sketch of arrangement attached. Project not proceeded with. The Wellington was superseded by the Mosquito and the resources for Gyrone were directed at getting a working gas turbine for the Meteor etc.
(intriguing what can be unearthed over a day at Kew, some other stuff to follow)

Aye T, & the Luftwaffe were flying very high altitude Jumo Diesel powered Ju 86 recce-bombers too,
Napier had the licence to build those aero-diesels, & utilized their tech for Deltic & Nomad.

& it took Stanley Hooker's 2-stage supercharging Merlin performance at high altitude in a Spitfire to
intercept those Junkers, after they had been quite troublesome.

The RAF did try turbo-charged B-17s for very high altitude attacks, but found them of little use..

 

[J.A.W.]

When looking at engines it is worth thinking what limits the engine life... there are quite a few things of course limit mechanical reliability but a crude measure is mean piston speed.... defined (imperial units) as MPS= RPM*S/6 ft/min..... S is stroke in inches.
The limit for a service aero engine is 3000 if reliability is to be maintained with good TBO. The RR 'R' engine had an MPS of 3500 and could be relied on to run for 1 hour. Merlin, Griffon and Crecy were all below 3025. Sabre was 3000 to 3166. Industry accepted figure for max reliable MPS is 3000. It would be worth a detailed look at the individual parameters of Sabre vs Merlin, say, to get a feel for what problems were built-in and what were due to lack of development before production. GP cars tend to 3400 MPS.
The RR Eagle II which we discussed in detail elsewhere on this site had a MPS of 2990 which shows how RR's service experience was built in to the initial design of the engine which some people assume to be a copy of sabre but was designed before RR had access to Napier's design... the OR was to develop a similar configuration of greater power.

The piston speed 'limit' has been a bit rubbery for a few decades, but in general it is a fair TBO indicator.
BMEP is perhaps a more meaningful number.

Funny that Ford's attempt to 'improve' the Merlin got stuck on the basic bore & stroke dimensions.

& R-R itself, while adept at developing their conservative V12 Merlin/Griffon, failed to match the
Napier Sabre with their radical 24cyl Vulture & would-be 'improved' Sabre-type Eagle 22..

 

[J.A.W.]

Perhaps it is a bit of a generalisation, but the conservative R-R approach to undersquare bore to stroke
architecture is something both Honda & Audi have continued with in automotive engines.

R-R conrod strength/bigend bearing issues are another matter, & the Reno race Merlins run Allison rods..

Mention of the long-stroke 36lt R-type R-R race engines running high pressures/MPS at the cost of ropy crank
& short TBOs brings up the comparison with the Napier Lion, which took the R's land-speed record.

For a WW1 engine design to be powering the LSR holder ~40 years after it 1st ran - was pretty good.
The Lion, an oversquare, slipper-piston DOHC mill, developed ~1,000hp over its initial output for the LSR,
again, a good effort for 24 litres..

 

[tartle]

The Reno racing Merlins do run at around an MPS of 3799 so you would expect some mods to be needed! The 'R' story is really a precursor to what happens at Reno today. As to the Eagle not being as good as Sabre... maybe the lack of development time is something to do with that.The use of MPS and semi-dimensionals based on that seem to work for Grand Prix engines so I would like to see the evidence that the parameter, as a generalised predictor, has lost its bite.
Arthur Rowledge designed both the Lion and the 'R' engine.

 

[J.A.W.]

'Grand Prix' engines these days are highly regulated exercises in SFC,
-so are more about economy than out-right power (with TBO being part of the economy equation), T.

The current F1 mills do have some parallels with your Whittle diagram though.

Mind you, 2-strokes with their inherent power density/mass/BMEP advantages - have been long since banned..

 

[J.A.W.]

The final (pre-ban) 2-stroke G.P. motorcycles were producing a reliable, tractable ~440hp/ltr.

Naturally aspirated, without forbidding MPS.

Albeit, they were highly developed units - using the principles worked out by ah, 'Nazi rocket science'..

Viz.. W. Kaaden's V1 sonic exhaust pulses via 2-stroke piston/reciprocation power transfer, effectively..

 

[J.A.W.]

T, do you have any info on S.Tresilian's hi-po X-16 proposal for R-R?

This fairly recent Lamborghini V12 marine racing mill must be reliable & have a reasonable TBO under stern use.

8.2ltr, 1100hp @ 7,500rpm - sans forced induction..

http://www.youtube.com/watch?v=FzoNIADg2mM

 

[tartle]

JAW,
This reference by very trusted authors...Piggott and Taulbut... indicates a maximum bhp/litre of 360. As I don't wish to get into a motorbike thread (not being where I want to go) may I suggest Taulbut's site is a great source of technical analysis of GP car engine design over the years. With the odd reference to aero engines.... which reminds me...
As we have seen from my other posts, I am intrigued by how the history of the development of the axial gas turbine compressor took shape... from Griffith's H1111 report in July 1926 to the Metrovick F2 in WW2...
Also I read a footnote in a GT Handbook that refers to Brown-Boveri completing a RR purchase order by delivering a 2.5 PR 190 hp axial aircraft supercharger.
Imagine my pleasure at finding this letter, below, at Kew... which raises a lot of supplementary questions!
Also Bristol was going down a similar track using an axial supercharger designed at RAE and constructed at Fraser and Chalmers (a GE subsidiary in Kent) Having been invited to do so by the Ministry.. the second letter below kicks off the cooperation.
Tresilian's stuff covered in another thread... try the search facility.

 

[J.A.W.]

T, why would Tresilian's stuff not belong on this thread? Was it another R-R technical no-go?

& notwithstanding your useful G.P. info posted.. (& I'm not referencing motorcycles per se)..
..the 125cc G.P. Aprilias were rated @ ~55hp in their final year - 2011, & were limited to 6 gear ratios,
which gives a clue to their tractability - even at those outputs.

Obviously supercharging, whether by forced induction or chemical pressure boosting will give more power.
Note that the Napier Sabre max power rating was for take-off, a sign of a strong mill..

 

[tartle]

If we were starting out on Tressy now we might put it here... but this thread is an outgrowth of the first one not vice versa... hindsight and all that would change every thread on the site. It is a forum where discussion drives... I think... but the moderators may have a clearer idea to guide me.

 

[J.A.W.]

Well, T - in post#63 - you included a couple of other post subjects into this thread..

Tresilian's design was for a fairly high BMEP design, but few X-types seem to pan-out as practicable.

Rowledge's W12 Lion was 3/4th of an X though, & worked well, - maybe that triple prime harmonic at work?

The 8.2 V12 Lamborghini bore/stroke is 97.7 x 89mm, & likely strong enough to substitute RPM for boost..

 

[J.A.W.]

Roy Fedden's review of the WW2 German piston aero-engines includes this comment re final Jumo 213 type..

"...appeared willing to accept an abnormally high piston speed & RPM."

Viz - 165mm (~6.5in) stroke turning 3,700rpm ( TBO?).

4-stroke mills are inherently 'lazy', thus require high rpm &/or pressures to produce good work..

 

[J.A.W.]

This clip (skip to ~3:30 for best effect) dynamically shows the exhaust jet/firing order of a 2-row radial..

http://www.youtube.com/watch?v=wMPdV6xA8X0