Thanks SSD! Regarding my original comment: I once stood fireguard on a starting Yak52 on which the prop when starting only went partially round and kicked back again (with suitable wheezing noises). The pilot then asked me to give the prop a shove in the right direction after which a normal start could be accomplished. After reading your post, am I right in assuming that this could be a case of a wrongly positioned prop? Does it feed air to all the cylinders at the same time (surely some will be on a compression stroke and won't benefit from it) or just several chosen ones? The aircraft had flown that morning just a couple of hours previous so there was no reason to pull the drain plugs I'm guessing.

The compressed air is fed via the pneumatic distributer to whichever cylinders are on the power stroke - so the air drives the engine round as if it was under power, but very slowly.

Your experience of 'kick back' indicates the pilot was (incorrectly) starting with the mags on. The 'shower of sparks' mag operates after TDC so the engine will fire and rotate the correct way at the very low speeds of starting. The normal mags fire before TDC (standard ignition advance), so will cause the engine to 'kick back' if they fire the mixture at low cranking (start) speed. The engine should therefore only be started on the 'shower of sparks' mag.

If you emove a mag distributer cap on the M14P, you will see that the rotor arm has two 'fingers'. One is for normal operation, the other is the retarded one for distributing the 'shower of sparks'.


SSD

T shirt
 

Wondering why so many Seafurys get converted to P&W's Is it availability?.

Polzin, yes purely supply, the big Bristols have nearly gone for ever,

Lu, I am lucky enough to own a very good Bristol Hercules(3 Hours, currently on loan to the Yorkshire Airmuseum), my father flew Beaufighters(in North Africa) which had the Herc fitted he told me that those engines used about 50 galls of oil per flight, but with the Carb feeding directly into the crankcase would this not be a two stroke engine, therby needing a lot of oil to mantain the lubricant on the facing between the cylinder wall and the actual sleeve valve and piston?
Peter R-B

Polzin, VFR,

Yes its availabilty.
Also bcause of their commonality and lots of knowledge in the US the P&W is much more tweakable for the racing guys.

He is a wartime advert for the Bristol sleeve valve, showing the workings, and in my experience the blurb is very true. The differences they highlight about valves are very true.
We had to adjust valve clearances on the P&W (1830) every 500 hours. It needs several guys to do this and takes a while. Northing like this on a sleeve engine.
http://www.thunder-and-lightnings.co...stolsleeve.jpg

Re oil consumption of course the British radials did use more oil the the US ones ( In my experience) which prompted comments like " Fuel cooled oil burning engines"

However we never considered it a real problem and certainly our Herks and Centaurus went out and back on flights without a problem
In the DC4 and DC6 we had overload oil tanks built in to transfer oil to the engines in flight, so oil consumption affected them all:D :D

I know this is going back a bit but, Lu, when you referred to the record setting HP/Capacity thing, you do mean that the 3350 was the first recip certified at that level, don't you? I would imagine the "craftsmen" at Rolls would argue that the Type R as fitted to the S.6 exceeded it's capacity in HP, by a substantial margin too I think. It just didn't do it for long......... Were there not also 1700/1800 HP merlins towards the end of production??

What a great thread. It's taken a while to get through all the comments, but here are a couple I'd like to add.

To 411A The Wright R-3350 is an amazing engine. Is anyone aware of another 'turbo compound' engine, where exhaust driven turbines put power into the crankshaft, as well as driving the compressors ?

Have you seen any literature on the Wright R-2160 Tornado ? 42 cylinders (6 rows of 7), liquid cooled, one overhead cam for each of the 7 banks etc. An amazing engine, but never got into production as piston engines were overtaken by turbo props. A work mate of mine has a book on the Tornado project. It's worth a look.

To Dale From my notes, the last of the Merlins (Model 133/134 as fitted to the last of the Mosquitos and Sea Hornets, had an output of 2,030 hp. This may be the best hp/cubic inch before the racers started to tweak them and the big P&W's.

Just to correct an oft made error, as quoted by S'nut727;

the Power Recovery Turbines [PRT's] on CW R-3350's only provide power to the crankshaft. They have nothing to do with the induction system of the engine, nor are connected to anything else on the a/c. ;)

G'day :D

G'day Feather. Thanks for pointing that out. I learn something every day.

I went looking for more info, and my questions were answered. I hadn't realised that the R-3350 has a 'conventional' centrifugal supercharger at the rear of the crank. Having a totally separate induction system explains how the PRT's could be an 'add on' to the later variants.

Were the engines in some B-17 aircraft not turbo-compound?

After an excellent landing you can use the airplane again!

Regarding the Bristol Hercules engines, the RNZAF Freighters were fitted with the Hercules 735s producing 2000 hp each. The oil consumption was 1 imp gallon per hour per engine. From memory there was 11 useable gallons in each tank.

Fuel consumption however, was a different matter. With full tanks and frugal power settings, you had over 12 hours endurance. Effectively, the aircraft was oil-limited!

The sleeve valve construction was a marvel! Without the limitations of fragile conventional valves, the cylinder head was as robust as a ceramic convenience. "Overboosting" was just not a problem. The standard way of clearing a mag drop was to apply full boost and min RPM and read the paper for a few minutes. Whatever was fouling the plugs was burned off in short order and the drop disappeared.

On one occasion this didn't work and after taxying back into the line, a wise old engineer (bless his oil-stained heart) tried another trick proscribed to mere aircrew: Max boost, max RPM and a series of slam-cuts of the throttle. Seemed to have the desired effect.

I was given an audio casette of Bristol Freighters starting up, taxying, running-up, taking off, cruising and shutting down. It was recorded at Blenheim NZ, of SAFE Air freighters. Forget who recorded it and having long misplaced it would be grateful if somebody could tell me where to get another. No narrative, just the mellifluous melody of the "Ug". Not a great conversation starter with the ladies though - can't imagine why? ;)

G'day Flash.

I think the later B-17 models had Wright R-1820's at 1,200 hp each. I think they had GE built turbochargers in the nacelle behind the engine, feeding air to the crankshaft driven centrifugal supercharger. I can't recall if they had 1 or more turbos per engine. Hence 2 stage supercharging, rather than turbo-compound.

Does anyone know of other turbo-compound engines than the R-3350 and possibly Napier models as mentioned in an earlier post ?

Several answers.
 

1) I believe that power recovery turbines were first used on heavy-duty freight engines powered by steam. Instead of the steam being vented from the steam chest or through the funnel it was ducted to the turbines and converted to mechanical energy, which was tied into the driving system.

2) My statement about the 3350 turbo compound being the first reciprocating engine to develop more horsepower than its’ cubic displacement came from a US Navy publication. The article claimed 3500 HP.


:cool:

Spec,
In 1945 some Merlins were giving 2,780 HP ( with Monomethyl aniline fuel additive. ) This was at 36 lbs boost.

The biggest RR engine was the Eagle which was rated at 3,500 HP

The Napier Sabre ( In Typhoons) gave over 3,000 HP .

Turbo compounded engines generally means that the engine is mechnically assisted by the turbine wheras turbocharging is using exhaust gases to increase the induction pressure.
Supercharging is an engine driven compressor which also increases the induction pressure.
An interesting engine was the Napier Nomad which was a diesel and gas turbine driving the same propeller shaft

Many of the superchargers were 2 speed ( high and low blower) and some were 2 stage ( one supercharger behind the other) and some Both 2 stage 2 speed.:D :D

The last P&W radial was the 4350 which went over 4,000HP and designed for the DC7. Douglas went for the Wright engine at 3,700 HP because it was lighter. ( and also Super Connie)

Actually Tshirt, the Pratt&Whitney R4360 (Wasp Major) was specifically developed for the Consolidated-Vultee (Convair) B-36. The only civil type that used this engine was the Boeing 377 Stratocruiser.

The largest CurtisWright R3350 turbo-compound engine fitted to the DC-7 was rated at 3400 hp (DC-7C, R3350EA4). In addition, the P&W 4360 was never considered for the Douglas DC-7 series, at least according to the engineering project manager for the DC6/7. Knew him well.

I'm getting a little off the original Radial theme, but there is so much great info along the engine size/power topic.

G'day Tshirt, here are some more comments.

1. I didn't know they pushed Merlins so hard back then. 2,780 hp from 27 litres (1,650 cu.in) is pretty good.

2. Yes the Eagle (22) was BIG at about 46 litres (2,800 cu.in) but obviously a lot smaller than a R-3350 or R-4360. What a complex arrangement, H 24 and sleeve valves, but similar to the Napier Sabre. My info is that the Eagle 22 was only used in the prototype Westland Wyvern, and short lived as the Wyvern went to a turboprop.

3. Maybe RR's biggest 'production' engine was the Griffon at 36.7 litres (2,240 cu.in). I know of variants up to about 2,400 hp. What were the latest Griffons in Shackletons rated at ?

4. I think Napier Sabres went to about 3,350 hp in the Tempest. A LOT of power from 36.7 litres, but ran at 4,000 RPM to do it.

5. Thanks for your explanation of turbocharging and supercharging. I think some of the later Griffons had 3 speed 2 stage superchargers. Also, another variation was the variable speed supercharger drive in the Daimler Benz DB605 (fitted to Bf109).

6. There's a Super Connie flying in Aust (VH-EAG). I've had a close look at it with cowls open and the R-3350's look great. Sounds great too. Hope to get a flight in it someday.

7. In Bris there's a flying Sea Fury. The sound of the Centaurus with 5 blade prop is MAGIC !!!

8. I hadn't heard of the Napier Nomad, so I'll do some digging for more info.

The Nomad was reckoned to be the most efficient piston engines ever designed.
A flat 12 supercharged (by an axial flow compressor) diesel of 41 litres producing 4100 hp.

For those of you wanting to know more about RR engines may I recommend Rolls Royce Piston Engines by A.A.Rubba, published by the RR Heritage Trust.

It covers the early engines through to the Exe and the Crecy.

There are photos, a wealth of detail on all the engines, and many cutaway drawings.

The HP debate between the R-4360 and the TC R-3350 I think ended up with a marginal win for the Pratt in normal ops [ie. not air racing.]

I believe the EC-121 Warning Stars in Vietnam had water injected R-3350's and they put out the 3,500HP+ mentioned. I'm doing some study at the moment for a spot of work next week and our charts only show 3,400HP with the 115/145 fuel [down to 2,880HP with 100 octane.]

What is great is that we can still see these leviathans of mechanical ingenuity operating in another century. If you happen to be at Avalon Friday week, don't miss the night show!!

G'day ;)

Feather #3

For efficiency, the CurtisWright turbocompound engines were certainly much better with a specific fuel comsumption of (approximately) .36/pound fuel/HP/hour.
No other large piston engine could compare.
Reliable...well yes, IF operated properly.

Which generally meant...the pilot left it to the Flight Engineer.
After all, with many airlines, HE had to help fix it if it broke....:eek:

411A,

Absolutely!!

The major lesson airframe drivers of this ilk need to learn is that you can only do what the power the F/E can give you allows. Many praise the pilots for flying the a/c when, really, you almost do so at the whim of the F/E.

Having said that, when the DA engines were in vogue and being screwed into the ground in terms of efficiency with advanced spark and leaning, some of the pilots carried their own power setting tables which allegedly saved engines for little extra fuel burn. Fortunately, we have EA's which burn more fuel, but are infinitely more reliable!!!:p

G'day ;)

411,

When Douglas designed the DC7 and were looking for an engine over 3,500 HP Pratt developed the 4360.

As I said Douglas went for the CW because of weight.
I find it strange that Douglas never even considered it because there was not exactly a plethora of 3,500 HP engines out there!:rolleyes:

The 4360 was also used used in the C119-C

Got the T shirt

The 4360 design was started long before the DC7 was ever thought of...as I mentioned before, specifically for the B36.

When the 4360 was installed on the Stratocruiser, the rear row of cylinders (four rows of seven) ran very hot, simply because the 'twist' (ie; cylinder row offset) was the wrong way 'round, as the engine had been developed for a pusher design.

Sorry...never considered for the DC7...as I grew up less than a mile from where ALL of the DC7's were built, and knew many of the folks involved (engineering project manager a close relative), the 4360 was never on the designers table.

Flew 'em as well...nice aircraft, but noiser than the DC6 (except for the -7C)

Nice try tho....;)

Lots of info on the web about the Sabre.

Ran 3,500hp at 3,850 revs. Triple 2 stage supercharger used an enormous 400hp.

Finally tested to 4,000hp ( and this in 1942/4 no exact date.) Fascinating story about improved sleeves coming from the Bristol Taurus.)

Prototype Wyvern was lost when the Eagle quit and the prop would not feather for forced landing. Not Westland's greatest plane.

I visited the RNZAF museum at wigram last weekend on their open day and had a look at their sectioned Sabre.Quite complex but not as physically large as i would have thought for the output it achieved.
They also had a sleeve valve demonstrator there of the turn the handle type, A couple of turns while watching the sleeve do its stuff and its workings becomes crystal clear.Clever stuff.

411,

[Sorry...never considered for the DC7...as I grew up less than a mile from where ALL of the DC7's were built, and knew many of the folks involved (engineering project manager a close relative), the 4360 was never on the designers table.]

The following is quoted from World Encyclopedia of Aero Engines by Bill Gunston

“The Mighty R-4360 had already passed its first test by June 1942 and later in the year was qualified at the unprecedented rating of 3,000 HP.
By VJ day it had been qualified at 3,500 HP.

The last throw was the R-4360 compound, which went beyond 4,000 HP. The vital application was the DC-7 and Wright won because the Turbo Compound was lighter and simpler. “

Of course this is a British Book, and Bill Gunston is a respected (but British)writer , I do live several thousand miles for where both the engine and DC7 were built and most of my relatives work on the buses
;) ;)


Isnt it strange how Pratt and Whitney got the twist the wrong way round. :confused: But then I suppose Douglas had already realised that
I guess this was before all the British designers emigrated there after the war.:p

For those of us brought up fooling around with auto engines the sleeve valve can be a bit of an enigma and what is interesting is how this apparent complexity can turn out, when done right, to be so reliable. It must be something to do with the lack of shock in the action and the relatively low acceleration of the parts.

It also has other advantages besides just the sheer size of the ports it allows, for instance the ability to renovate by just pulling and replacing the sleeve. Granted the high friction area between the sleeve and the block must make the power requirement for starting a bit of a nightmare.

Seems a bit surprising there is not at least one eccentric auto manufacturer out there building a sleeve valve engine instead of the four or even five valves per pot jobs that are around now.

T shirt,

That's just the point, Pratt&Whitney designed it that way...the right way 'round, for the B36.
Used on the C124, B50 and some models of the P2V...was a basic military design engine. If you are ever in KSFO, take a ride down the 101 freeway to the Hiller Helicopter museum at the San Carlos airport.
There you can see a rotating cutaway of the 4360...lots of bits and pieces all flailing around in close formation....;)

411A

Ok now I think I've got it !!

Pratt and Whitney, desperate to get into the radial engine business built an engine for the B36 which was a pusher engine.

Then to get more business they got it put into the C124, The C119 and the P2V but no one told them these engines were pullers rather than pushers.
Pratt thought that all they had to do was change the prop the other way round and bingo.

They then found out the hard way that the front cylinders were now in the back and it all went downhill from there.

Fortunately by then the all the jet engine people emigrating from Europe went to work for them and they got into the jet engine business and the rest as they say is history !:D :D

Ummm....

GGTs ,

P&W were in the radial business way before the R-4360!

The R-985/1340/1830/2000/2800 all spring immediately to mind [altho introduction of the R-2000 may be a bit out in this context?]

G'day ;)

Tshirt,
Pratt&Whitney...desperate?

Ah, well no actually. The 4360 was used because it was available off the shelf, so to speak.

But on the other hand, the folks at General Electric (the American company) used their developmental talents with turbochargers, to lead the USA into the jet age. A rather joint British-American effort.
The Brits did indeed lead for awhile with turbo-shaft design.
The Dart and Tyne are two good examples.

But then Allison came along with the 501 series....superb.;)
Now there's history:cool:

My dad always reckons that the Hercules sleeve valve design was most reliable and that the sleeve crank spindle, although small, rarely caused problems.

He only had 4 engine failures during his flying career and it was bits of German metal imposing themselves on good Bristol engineering that were to blame!

The poppet valve is not an elegant engineering solution is it. Functional yes, functional but requiring "constant" attention also yes. Unfortunately it's always the cheap and cheerful solutions that bean counters go for not the long term savings that good engineering can offer but cost a bit more in development. :rolleyes:

Yeah, but what about.......?
 

To: Feather #3

Here is the complete listing of air cooled P&W Radial engines:

R-985
R-1340
R-1535
R-1830
R-2000
R-2180
R-2800
R-4360
R-1690
R-1860
R-2180A

Here is the complete listing of liquid cooled P&W reciprocating engines:

R-2060
H-2600
H-3130


:cool:

Lu, I think I've also seen references to R-1300, R-1590, and R-1820

Also an X-1800, but I think this may never have gone further than prototype stage, like the R-2060.

Did the H-2600 and H-3130 make it into production ?

Gee Lu, I did say immediately!

Thanks for the encylopediac listing. :D

Given that my list was of the more common types [plus, of course, the R-4360], would you mind giving some aircraft types to which the more esoteric [eg -1535: Hughes Racer?] models were applied, please?

G'day ;)

I read it in a book.
 

My source of information was the Aeronautical Vestpocket Handbook published by United Technologies Pratt & Whitney. Although there is reference to which turbojet engines were installed on which aircraft there is no reference to what airframes the more esoteric engines were installed on. I do not know if any of the lesser-known engines reached production. There were a lot of experimental aircraft that never reached production and I can only assume that those engines were designed for installation on those aircraft.

I would suggest you reference Janes as they once published a handbook on all the worlds reciprocating engines both production and experimental and they may have referenced the aircraft that the engines were installed on.

:O

Here's a few of the scarcer types.

The P&W R1535 was a 14 cylinder Twin Wasp used on the Boeing 247 and the Bristol Bolingbroke.

The R1690 was a 9 cylinder single row that came as a direct drive or geared version. The direct drive version was used on the Bellanca C27 and the Sikorsky S4, and the geared version on the Martin B12, the FW 200 and the Lockheed 14.

The R2000 was of course used on the DC-4/C-54 and the DHC4 Caribou. I've also flown an executive DC-3 that had the R2000's installed. Great airplane. It gave you a gross weight increase from 26,200 to 26,900 lbs. for the passenger version, the same as the R1830-94 equipped version.

Even numbers are possible!
 

Even numbers are possible - you just have to know where to look . . . at two stroke engines for example.

Koenig made a very nice little 4 cylinder radial two stroke for aircraft - admittedly only 28HP but it is still a radial and it is a lovely smooth engine to fly with.

The reason that four stroke radials have odd numbers isn't to do with the which way to turn but with the natural vibration modes built up and re-inforced by power pulses.
ALL horizontally opposed twin 4 strokes are really not nice and to get one to run smoothly you have to either run a balance shaft or live counter-wieghts on the crank.

When you tack two together as a flat four its a bit better but to really get it smooth go for a flat 6 as the power pulses are then 120 deg apart and cancel each other rather than re-inforce.

The two stroke can get away with flat twins and radial fours because the number of power pulses is doubled.

And you don't have many problems with valve gear and oil loss on a 2 stroke because there ususally isn't any and if it stops spitting oil that's when the trouble starts.

And finally, not all radials use master/slave con-rods with offset pins giving eccentric slave motion to the crank shaft. There are engines that use slider/slipping slave con-rods but they are in the minority and it is the offset pins that people remember.

TTFN

If anyone is interested I would be happy to copy and mail the six pages I have found in Flight of 16 February, 1939 entitled 'Sleeve-Valve Development', the story of the successful work of the Bristol Company: Mr. A.H.R. Fedden's R.Ae.S and I.A.E. paper. Drop me an email to [email protected]

...and I might add the nine pages published a few weeks later 'Rise of the Radial'..!

Even better is the chapter in "Fedden - The life of Sir Roy Fedden" by Bill Gunston, published by the RR Heritage trust.

The book is a worthy addition to the bookcase of anyone interested in sleeve valves and radial engines in general.

The RRHT have a web site which lists the books they publish:
in addition to those about cars there are plenty to interest the aviation engine enthusiast.

PS: ATB, not trying to steal the thunder from your very generous offer, only pointing out other options.

No probs at all with that, Henry. I do feel, however, that original, unadulterated, magazine articles offer a certain charm in comparison to a book over which the author has perhaps had time to evaluate all the information and arguments available to date. Interestingly enough, Felden presented his paper to Rolls-Royce a few weeks later and was apparently inundated with questions.

cheers

Bluebottle