Armstrong Siddeley Tiger Improvements

[Old Paul]

I came across this post - http://www.alternatehistory.com/discussion/showpost.php?p=9610446&postcount=15 - which prompted me to check out the Tiger. (Only on Wikipedia, unfortunately) Very sparse info, but about 33 litres (roughly an R2000 equivalent), the first British engine with a two-speed supercharger and first run in 1932. Seems to have suffered from lack of development, but could this have been a viable "early Hercules"? Or perhaps a good engine for FAA use?

PS - Came across this excerpt from John Denshams obituary - He joined Armstrong Siddeley in 1938 working under Sid Allen on a Tiger aero-engine single cylinder rig. The Tiger then suffered from certain serious problems.  Densham's strongly held (and controversial) view was that the company's demise in piston aero-engines was not due to the Deerhound, but the inability to develop the Tiger by 1939 into a reliable "so-called 1000hp" unit.

[Captain Canada]

Quite a few pics of it on Google, bolted to alot of aeroplanes I've never seen as well !

[Old Paul]

Does anyone have any info on the Tiger development, or can you suggest a reference? Seems to be very little available.   I'd particularly be interested in the "serious problems" and whether there could have been a fix for these.

PS - I did come across this - http://www.enginehistory.org/Piston/AS/AS/armstrongsiddeleyengines9.html

[wuzak]

British Piston Aero Engines and their Aircraft by Alec Lumsden is a good start. It doesn't give detailed accounts of the development of engines, just descriptions of the various versions of each, and what the changes were. It also has a table of the engines and their rated power.

The Tiger VIII is listed as 918hp @ take-off, 2375rpm, +2.5 boost.

Normal Power
MS: 840hp @ 6,250ft, 2375rpm, +5psi boost
FS: 760hp @ 12,750ft, 2200rpm, +5psi boost

Max Power
MS: 862hp @ 6,750ft, 2450rpm, +5psi boost
FS: 782hp @ 14,250, 2450rpm, +5psi boost

Weight - 1294lb.

All Tigers seem to have been rated on 87 octane fuel.

100 octane or 100/130 fuel shoudl have allowed increased boost, if the engine could handle it, but at lower altitudes.

The Tiger seems not too dissimilar in power to the early P&W R-1830s, though it is larger in capacity (1995ci vs 1830ci) and diameter (50.8" vs 48.0").

[Old Paul]

Thanks - seems to be all the information available. I know there are still one or two about - one in the Science Museum. I wonder if they'd have anything more?

I was thinking it was more comparable to the enlarged R2000 Twin Wasp. Slightly larger in length and diameter, but also lighter according to Wiki, although they don't say whether this includes all ancillaries for both engines. 

I do wonder how the early availability of a reliable 1000-1100hp radial could have improved FAA procurement in say 1937-39?

[Old Paul]

Perhaps Armstrong Siddeley outsource development to Ricardos? 

[wuzak]

I was thinking it was more comparable to the enlarged R2000 Twin Wasp. Slightly larger in length and diameter, but also lighter according to Wiki, although they don't say whether this includes all ancillaries for both engines. 

The Tiger VIII is 300lb lighter than the R-2000, and was the heaviest Tiger. It was less than 1" bigger in diameter, and its extra length may have been due to having a 2 speed drive. Wiki doesn't specify whether the R-2000 had 2 speed supercharger drive or not. Some R-1830s had 2 speed drives and some didn't.

[jcf]

R-2000 specs:
http://www.enginehistory.org/P&W/R-2000/R-2000Index.pdf

How to read P&W designations  :
http://www.enginehistory.org/P&W/PWdesignations.pdf

From this page:
http://www.enginehistory.org/reference.shtml

Scroll down to the P&W links.

The Twin Wasp/R-2000 supercharger was 1-stage, 2-speed.

[wuzak]

R-2000 specs:
http://www.enginehistory.org/P&W/R-2000/R-2000Index.pdf

How to read P&W designations  :
http://www.enginehistory.org/P&W/PWdesignations.pdf

From this page:
http://www.enginehistory.org/reference.shtml

Scroll down to the P&W links.

The Twin Wasp/R-2000 supercharger was 1-stage, 2-speed.

Thanks.

[Old Paul]

I'm still not convinced about the weight comparison with the R-2000, particularly as the Tiger has steel barrels and the R-2000 appears to have alloy barrels, presumably with steel liners. Can anyone confirm this?

However, assuming Sidney Allen starts work on an improved Tiger earlier, perhaps with some input from Harry Ricardo, a reliable 1000hp class Tiger doesn't seem unreasonable for perhaps 1938? And hopefully a mature engine by this time. The later Whitleys could have continued with this rather than Merlins. What else could this have been used for? Albacore? Uprated Gloster F5/34? European exports? And how much could things improve with 100 octane fuel?

Might this have encouraged a preference for radial engines for FAA aircraft as well? Perhaps going from Tigers to Hercules to Centaurus?

[wuzak]

I'm still not convinced about the weight comparison with the R-2000, particularly as the Tiger has steel barrels and the R-2000 appears to have alloy barrels, presumably with steel liners. Can anyone confirm this?

However, assuming Sidney Allen starts work on an improved Tiger earlier, perhaps with some input from Harry Ricardo, a reliable 1000hp class Tiger doesn't seem unreasonable for perhaps 1938? And hopefully a mature engine by this time. The later Whitleys could have continued with this rather than Merlins. What else could this have been used for? Albacore? Uprated Gloster F5/34? European exports? And how much could things improve with 100 octane fuel?

Might this have encouraged a preference for radial engines for FAA aircraft as well? Perhaps going from Tigers to Hercules to Centaurus?

I'm not sure with the R-1830 and R-2000, but the R-2800 had steel barrels with aluminium cooling fins press fitted over the top.

[Piper106]

Revised.

I wonder if the Tiger was one of those two row engines that did NOT have a center main bearing between the rows.  

"Aircraft Engines of the World" from the 1939 edition of "The Aerosphere" indicates that the Tiger was a two bearing engine, that is, no center main bearing.  

For example, the Gnome Rhone 14N two row engine did not have a center main bearing.  Their development hit a wall fairly quickly.

As with the Gnome Rhone engine, the basic design of the Tiger (ie. two bearing crankshaft) is a likely reason for the lack of development of the Tiger.  If the rpm or bost were moved up, connecting rod big end bearing failure, main bearing failure, or crankshaft breakage was the likely outcome.

Make the Tiger strong to handle higher HP, and the "300 pounds lighter than an R-2000" weight advantage goes away.  

[jcf]

Another issue is that in its bones the Tiger was a development of the Jaguar, which
went back to the R.A.F.8 of WWI.

Jaguar begat Jaguar Major(renamed Panther) begat Tiger. The displacement increased
at each stage but not the fundamental design.

[Old Paul]

So the root issue may be a redesign needed to include a central bearing? Either as a Tiger X or a new designation?

Is there anything inherently wrong/dated about the basic design? Are more modern engines mild refinements or a whole new generation?

Instead of the three-row Deerhound, perhaps Armstrong Siddeley should have concentrated on a more up-to-date twin-row engine to develop (earlier?) as an R-2000 equivalent?

[wuzak]

Armstrong Siddeley wanted to make the Deerhound liquid cooled. But the Air Ministry overruled them as they wanted a competitor in the air cooled market to Bristol and the Hercules.

At 2260 cubic inches (Deerhound I) it was slightly larger in capacity than the R-2000, but was beset with problems and could only manage 1100hp or so.

The Deerhound II and III were enlarged to 2505 cubic inches, the II managing 1800hp.

But even with its (relatively) short stroke of 5" it only managed 2600rpm, so obviously there were still some issues there.

The selling point of the Deerhound would have been its frontal area - only 44" in diamater. Compared with the R-2000's diameter of 49.5", the R-2800's 52.5", R-1830's 48", the R-1820 and R-2600 at 55" and teh Hercules at 55"as well.