Advantages of sleeve valves for H-24 engines?

[Simon Thomas]

Maybe they wanted to standardize engines?
The GR-2800-A5B was used in most of the A-20s, it was used in the early Martin Baltimore's ( the first 3-4 marks).
In 1940 and early 1941 I am not sure what was going on as far as releasing certain model engines for overseas sale. By late 1941 things were very different and the while the Dutch didn't their B-25s in time they had been ordered with the 1700hp engines.

All I know is that the GR-2600-A5B was not the latest and greatest R-2600 at the time the Hercules XI showed up. In fact the 5th production R-2600A was delivered in March 1938.
Wright was working on the R-2600-B in Nov 1938, test ran the first one June 1940 and delivered the 5th production engine June 1941 if that helps any.
The later R-2600-BB engines (1900hp) kept the bore and stroke, much like some of the later Hercules only kept a few parts.

Standardizing the engines makes sense. The lead time to get them from the US was significant.
The book mentions this about engine shipments:

The aircraft factories did not escape the attention of the Luftwaffe; two bombing raids at Belfast caused disruption and widespread damage. On the night of 7/8 April 1941, the Harland & Wolff, Alexandra works was badly hit; the only source of fuselage frames, associated jigs, and tooling was destroyed. During this raid a ship from the USA was at the docks awaiting unloading; it contained a consignment of crated Wright Cyclone engines for the Mk II Stirling project. The ship received a direct hit.​

 

[J.A.W.]

When was that?

Sorry, my 'goggle fu' has failed me on 'straya day. IIRC (I'm on shaky ground with this one) ah, IIRC, the engine still exists in Switzerland, dated
to the mid `70s & was a development of Hewland's single cylinder research engine (~70hp from a 500 4-stroke single, or 'bout ten up on
the best GP Manx Norton, the bench mark for a 4-stroke 500 single - & the flow-tech for the successful Vanwall F1 cars) that is, back when
Cosworth were concerned the DFV may be at risk of being eclipsed (it wasn't, & remained competitive, & a good earner.

Edit: This is a late entry due to my (quite rightfully applied/accepted) 'naughty stool/time out' from this thread, recently completed.

 

[J.A.W.]

JAW: "There still were (& are) a number of those advantages - which are inherent mechanical attributes - remaining relevant, as it happens."

The point I understood being made by J.A.W. was that there were advantages relevant to today, not if just about the best sleeve valve ever made was fractionally
better than a very run of the mill 2-valve per head poppet engine.

I would say that this sort of study is more or less a nonsense in as far as using it to compare sleeves vs non sleeves, as they are completely different engines, all you`re doing is comparing the engines not the method of their valve operation. It would be impossible to normalise the other factors to isolate what effect the sleeves were having. Its also
a terrible comparison anyway for reasons mentioned. You might as well test a Kestrel against an R-2800 and say "look see, air cooled is better"

There is no global law today against using sleeves for any production vehicle you wish, yet nobody bothers.

The reasons for adopting it, relevant once about a century ago, simply dont exist now.

Lets address these three points:

1) Performance, it obviously does not have the best performance as in wartime it was never boosted above +11lbs with any sucess (+17lbs came after the war ended), meanwhile
the best poppets were running +25lbs and the Merlin 100 type tested during the war and passed at +30lbs. No amout of arguing about a bit of swirl here or tumble there is going to
get you ahread when you cant even run at half the boost of your competitors. The Sabre did reasonably
well as it ran fast, a good design idea which was due to the short stroke and nothing what-so-ever to do with
sleeves (which have appaulingly high friction and inertia - Napier admitted that also the oil consumption
was horrific and they never got it even near a poppet valve for that figure either).

(Sabre VII oil consumption was about 50% higher than a BMW-801 and about 25% higher than a Merlin)

2) Fuel consumption, nope, the best consumption was shown by direct injected poppet valve engines, which
were getting towards 190g/Hp/Hr

Bog standard DB 601 = 213 grams/hp/hr
Sabre VII = 248 grams/hp/hr (at maximum weak cruise, its a lot worse for other conditions)
Merlin-66 = 225 grams/hp/hr (maximum cruise)



3) Noise - The only wartime report I`ve EVER read which mentions noise being a problem were when the
2-stroke was being considered for the Spitfire. The noise was considered likely to be so deafening as to
be able to actually incapacitate the pilot.

Ok, per Wilkinson:
& comparing the final fighter engine variants of the Sabre & Griffon, of the mark which appeared on the same page in the previously
linked 'Flight & the Aircraft Engineer' journal article - here are how a few vital engine stats as tested, compare:

-----------------------Sabre VII-------------Griffon 69 - an OHC 4V poppet.

Weight to hp -------0.33kg/hp------------0.47kg/hp
Output: (max)--------95.4hp/ltr------------54hp/ltr
Fuel: (cruise)---------205g/hp/hr-----------225g/hp/hr
Oil: (cruise)----------6g/hp/hr--------------7g/hp/hr
BMEP: (max)---------22.6/kg/cm2----------18.0/kg/cm2
Boost: (max)--------1790mm/hg*----------2052mm/hg**

*Available on ADI/130 grade avgas
**Available on 150 grade avgas

Edit: More later, such as evidence for sleeve valve combustion efficacy - the faint - almost complete absence of - exhaust flare/flame.
& other relevant matters, like the higher BMEP on less boost, as a volumetric-efficiency indicator.

 

[J.A.W.]

2340hp
@ +30lbs boost,
3000rpm - date 28th Oct 1944
Bhp/Litre = 87 (this is higher than any type tested Sabre power rating)

Ah, no...

Wilkinson has the revised/final Sabre VII "power rating" showing Bhp/Litre = 95.4, as it happens.

 

[Deleted member 68059]

Ah, no...

Wilkinson has the revised/final Sabre VII "power rating" showing Bhp/Litre = 95.4, as it happens.

Yes and I here have a bit of notepaper, on which I will now scribble that the top speed of a Spitfire Mk 1 was 900mph.

That means just as much as that claim does, as there iz no evidence for it what-so-ever.

 

[Deleted member 68059]

Ok, per Wilkinson:
& comparing the final fighter engine variants of the Sabre & Griffon, of the mark which appeared on the same page in the previously
linked 'Flight & the Aircraft Engineer' journal article - here are how a few vital engine stats as tested, compare:

-----------------------Sabre VII-------------Griffon 69 - an OHC 4V poppet.

Weight to hp -------0.33kg/hp------------0.47kg/hp
Output: (max)--------95.4hp/ltr------------54hp/ltr
Fuel: (cruise)---------205g/hp/hr-----------225g/hp/hr
Oil: (cruise)----------6g/hp/hr--------------7g/hp/hr
BMEP: (max)---------22.6/kg/cm2----------18.0/kg/cm2
Boost: (max)--------1790mm/hg*----------2052mm/hg**

*Available on ADI/130 grade avgas
**Available on 150 grade avgas

Edit: More later, such as evidence for sleeve valve combustion efficacy - the faint almost complete absence of exhaust flare/flame.
& other relevant matters.

Ah "Wilkinson" - another table from the "write any number we want" school of publishing.

What is the archive reference for that table to a Napier report ?

 

[J.A.W.]

I think somebody's pen slipped or dripped.
150hp X 36.7 liters is 5,505hp
A 3000-3055hp Sabre used 280lb/sq in BMEP.

That one, if you 'do the maths' evidently correlates to the '5,500hp flash reading sans limits of boost/fuel/cooling constraints' specified
by Setright, & it would also correlate (base vs highest achievable with the figures obtained from sprint racing tuned Allison/Merlin as
used in tractor pulling/hydroplane drags & whatnot motorsports these days.

Take into account the cylinder ported flow advantage & lack of valve bounce/bind/seat-deformation/poppet-head obtunding ports/heat-soak...

 

[J.A.W.]

Ah "Wilkinson" - another table from the "write any number we want" school of publishing.

What is the archive reference for that table to a Napier report ?

Say aren't you the guy who'd dismissed 'Flight..' as mere British propaganda bullshit, then posted up the same drawing as 'Flight' published
of the E122 '500mph' no-tail fighter?

As for Wilkinson, his sums check out, & he put on the record that it was "Standardised data", & "revised" when updated data was released.
Have you located the Air Ministry Type-test Archive yet? Find the relevant data there before "write any number we want" comments perhaps?

As for "...any number you want." - Did you check the maths, Wilkinson sure knew how to do that - since the figures correlate, no typo there...

 

[Deleted member 68059]

Say aren't you the guy who'd dismissed 'Flight..' as mere British propaganda bullshit, then posted up the same drawing as 'Flight' published
of the E122 '500mph' no-tail fighter?

As for Wilkinson, his sums check out, & he put on the record that it was "Standardised data", & "revised" when updated data was released.
Have you located the Air Ministry Type-test Archive yet? Find the relevant data there before "write any number we want" comments perhaps?

As for "...any number you want." - Did you check the maths, Wilkinson sure knew how to do that - since the figures correlate, no typo there...

Correlates to what? His own incorrect data ? I worked out the consumption from the sabre VII data sheet - from Napier .

The E.122 page you don't like was from a lecture given BY NAPIER

 

[Marcel]

Yes and I here have a bit of notepaper, on which I will now scribble that the top speed of a Spitfire Mk 1 was 900mph.

That means just as much as that claim does, as there iz no evidence for it what-so-ever.

Repeatedly moderators have asked to keep the personal sneers at home. I close the thread for a few days, so you guys can do a little thinking about your behaviour.

 

[DerAdlerIstGelandet]

Sigh, like a kindergarten..,

Such childish behavior from many.

And leaving the forum because you are asked to act like an adult? What are we 14?

 

[DerAdlerIstGelandet]

Seriously, as an adult just walk away and ignore someone. This "I feel insulted, I'm taking my toys and leaving" is ridiculous.

 

[Simon Thomas]

Now that is disappointing.

Re the Setright power figure.
In the book "By Precision into Power", Vessey on page 135 states:

a twin "Sabre VI" annular radiator installation was tested in a Vickers 'Warwick' bomber at Luton, a multi-engine arrangement with military or civil transport aircraft in mind and 5,000 bhp on tap.​

I'd suggest there is a slim possibility that Setright misinterpreted that 5,000 bhp number as the power from a single engine.

 

[DerAdlerIstGelandet]

I'm still annoyed by this…

So sad that an otherwise interesting and informative topic and discussion is ruined because multiple people cannot act decent and civil.

 

[DerAdlerIstGelandet]

Just for the forum membership to know, Calum had his account deleted at his own request… smh

This was not a banning or anything. He was not in trouble. He asked to have his account deleted.

 

[Trilisser]

By the way, regarding specific fuel consumption: The Hercule operator's handbook (covers VI, XI, XVI, XVII and XVIII) quotes a example: 730 hp, 1600 rpm and +2 boost. 42.5 Imp. gallons/h. This works out to 191 g/hp/h. Fuel specific gravity 0.72 kg/l.

Also a Twin Wasp description (Pratt&Whitney document) has sfc curves in which the combination of 1450 rpm and approx. 420 hp gives 190 g/hp/h ("with 3 % tolerance").

A Bramo 323 description for 323 C-D gives the lowest sfc as about 190 g/hp/h.

 

[MiTasol]

Just for the forum membership to know, Calum had his account deleted at his own request… smh

This was not a banning or anything. He was not in trouble. He asked to have his account deleted.

I have not been following this thread and will not go back through it but that is the worst news I have seen in a long time. The man is a font of knowledge and knows how to explain complex subjects in simple terms. A rare ability.

 

[DerAdlerIstGelandet]

I have not been following this thread and will not go back through it but that is the worst news I have seen in a long time. The man is a font of knowledge and knows how to explain complex subjects in simple terms. A rare ability.

This was not a moderator action. He and J.A.W (who is re-banned) got into an argument and Callum asked the Moderator staff to delete his account. It was unnecessary, but we cannot force him to participate if he does not wish too. Quite honestly, I found his request rather childish as well.

 

[b0ned0me]

This was not a moderator action. He and J.A.W (who is re-banned) got into an argument and Callum asked the Moderator staff to delete his account. It was unnecessary, but we cannot force him to participate if he does not wish too. Quite honestly, I found his request rather childish as well.

TBH its not rare for someone to decide they've spent enough of their energy on a forum/game/whatever and ask for their account to be zapped, avoiding the temptation of returning and wasting even more. Childish would have been deleteing all his previous posts first, which I have seen people do sometimes . At least we can still read the stuff he has contributed.

Also not rare that letting banned people back on a forum without very strict supervision leads to exactly this outcome, re-banning them after they have wasted a ton of moderator time plus goaded other members into bans or leaving.

 

[SaparotRob]

Now I feel bad about making fun of pben's shoes.