Jump to content

Historical Engine technology


coe

Recommended Posts

This isn't specifically a game question but a WWII question I haven't been able to find much on (so if someone can point me in the right direction I'll close this down right after).

I was looking at German and Allied engine technology and was wondering how they stacked up at various points of the war in vehicles (land and air) ... for instance allied engines in airplanes (not jets) were regularly getting 2000 hp alot sooner than german engines. Were tanks and trucks and half tracks affected similarly?

Link to comment
Share on other sites

The Germans had relatively poor engines in the Panzer III and IV chassis vehicles because they were pre-war designs, and the vehicles grew in weight due to uparmoring, beyond what the original chassis had been engineered for. Thus e.g. a late Panzer IV had only 300 hp (from a V-12 engine - not an impressive power per cylinder) for a 25 ton (metric) tank.

But the heavier later war items had better engines, 650-700 horsepower. In a Tiger I that was still only adequate, because the tank weight was so high, more than double the Panzer IV. In a Panther, though, half way between in weight but with the full power of a Tiger engine, it gave good mobility. The Panther was the exception, though, to mediocre power to weight ratios in German tanks.

The Brits were even worse until the Cromwell. Previously you get things like the Valentine, lighter than a Panzer IV at 16 to 20 tons (early and later models), but with like 130-140 hp engines - less than my Subaru Forester (lol). A Churchill had a 350 hp engine, about the power of a late Panzer IV, in a tank as heavy as a Panther. A Crusader used about the same engine power in a 21 ton tank, making it marginally better than a Panzer III or IV, and that made the Brits consider it an exceptionally fast tank. But it got that way by using a relatively weak engine in a very light, underarmored chassis and design.

The US Shermans had 450 hp for the earlier models and 500 from the later ones, in a 30-32 ton tank. It got those 500hp from a very efficient V-8 engine, but there wasn't anything bigger pulling US tanks. The Russians got 500 hp from a V-12 in the T-34, and in a lighter tank than the Sherman in the case of the 76mm ones. The T-34/85s were the weight of a Sherman and still had 500 hp. This made all of these tanks quite mobile - the Russians also had good flotation from wide tracks, which the Sherman didn't get until the E8 model. Compared to a Panther of Tiger, they have engines with 70% of the horsepower moving around a chassis with 2/3 or 1/2 of the weight, respectively. Thus only the Panther is in the same mobility class.

The Brits got a good tank engine by 1944 in the Meteor (based on an aircraft engine). That powered the Cromwell - a 29 ton tank lighter than a Sherman - with 600 hp, making it about the most mobile medium of the war. It was however underarmored and underarmed for its day - too much engine for not enough tank to be truly battle effective. The same engine was put in the post war Centurion of 43 tons (Panther) weight, and was effective once mated to that heavy a chassis. The result was a bit underpowered compare to Panther or Sherman or T-34/85, but a capable heavily armored tank that could move etc. Tiger I like mobility or better.

In contrast, the US Pershing limped along at the same weight as a Centurion or Panther with the same engine used in the Sherman, pretty much, only 500 hp for a 45 ton tank. Which wasn't nearly good enough, and in Korea with its hills in particular, the Pershing proved to be a pretty hopelessly underpowered tank. Note, however, that is about the same hp to weight ratio of a Tiger I. This wasn't solved until the Patton series which put an 810 hp engine in a 45-50 ton tank, restoring the power to weight ratio of a Panther, Sherman, or T-34/85.

I'd put it this way -

automotively hopeless - Brit I tanks

just OK, barely livable mobility - Panzer IVs, Tiger Is, Pershing, Centurions

good mobility - Shermans, T-34s, Panthers, M-48 Patton

Thing was, the Panthers were only 15% or so of the German fleet, while the Shermans and T-34s were 2/3 to 3/4 of the allied fleets.

Pattons and Centurions with solid power plants mated to Panther size and equal or better power as tanks, only came postwar. And in the US case, post Korea even.

FWIW...

Link to comment
Share on other sites

One tidbit I read about aircraft engines somewhere is that the Me 109 fighter had something like a 700 hp engine in 1939, and a 1800 hp one when the war ended. Unfortunately, the maxed-out late-war engine lasted only about 10-12 hours in flight before it was worn out, but considering that most likely the fighter wouldn't last that long anyway, it made sense. Not sure if it's true, though.

Link to comment
Share on other sites

The same engine was put in the post war Centurion of 43 tons (Panther) weight, and was effective once mated to that heavy a chassis. The result was a bit underpowered compare to Panther or Sherman or T-34/85, but a capable heavily armored tank that could move etc. Tiger I like mobility or better.

Probably a bit better than that as it was the Israelis preferred tank on the Golan Heights and the reason usually given is that it had better mobility in that kind of country than the M48.

Michael

Link to comment
Share on other sites

Tank mobility is not a direct relationship to HP. Torque is more important in engines than BHP particularly so for land transport. Airplanes it is BHP because their is no need for huge torque.

For instance I just saw a video for a 1970's Oldsmobile Cutlass which had a 7 litre V8 engine and produced about 225BHP. My car gives over 230BHP from a 2.6litre engine. If I was asked to tow a boat or a caravan I would want the Cutlass as its engine has more torque - more pulling ability.

Diesels generally have more torque and were inherently more reliable and robust than petrol engines. This has to do with being built stronger because of higher compression and perhaps most importantly much less electrics to go wrong.

The Russians, ignoring maintenance issues and poor workmanship, had the most efficient engine choice.

Reverting to tanks. The Churchill had a very specific brief and that was mobility not speed. In that it succeeded and was able to get to places other tanks could not. This could be decisive. It also had numerous bogies because they could have several shot out without the tank being disabled. And as an infantry tank what need of speed?

The Meteor engine was a de-rated Merlin and its use for tank engines was already under consideration in 1941.

Other considerations that might have a bearing other than purely engines are the mechnicals for getting power to the tracks and the larger German tanks were notorious for clutch problems if used to their nominal potential. Alsobear in mind that German tanks, or at least some of them could turn in situ, not something the Sherman could do.

I am not sure if you want detail on the Russian/German/French/Italian/Allied engines for trucks etc. But power in BHP is not shiftability in terms of cargo. Diesel engines have lower BHP than petrol engines but would shift the same amount of kit because they have greater torque.

On the aero-engine front from my reading there was a steady escalation of outputs through the war and at any one time one nation may have had a more powerful engine than another. The Merlin obviously was outstanding from the off and perhaps that would be the benchmark.

Power in itself ....... The B29 suffered because the powerful Wright engines had a tendency to overheat ... which would be the situation at low level taking off with a full bombload when max revs were required. So simply having a very powerful engine did not mean it was reliable and one you would actually use. In fact failed aero-engines occur quite frequently in the history of plane design.

If you look at the Wiki article on the Merlin you will see how changes in coolant and octane of petrol wee alos important to engine outputs. Here are the WW2 variants, pre-war it started out as a 740 hp plane engine

This is a summary list of representative Merlin variants. Engines of the same power output were typically assigned different model numbers based on supercharger or propeller gear ratios, differences in cooling system or carburettors, engine block construction, or arrangement of engine controls.[67] All but the Merlin 131 and 134 engines were "right-hand tractor", i.e. the propeller rotated to the right when viewed from the rear.

Data from Bridgman (Jane's)[68] unless otherwise noted:

  • Merlin II or III

1,030 hp (775 kW) at 3,000 rpm at 5,500 ft (1,680 m) using + 6 psi boost (41 kPa gauge; or an absolute pressure of 144 kPa or 1.41 atm); Merlin III fitted with "universal" propeller shaft able to mount either de Havilland or Rotol propellers,[69]1,310 hp (977 kW) at 3,000 rpm at 9,000 ft (2,700 m) with 100 octane fuel and +12 psi boost (83 kPa gauge; or an absolute pressure of 184 kPa or 1.82 atm) (Merlin III);[43] both used in the Boulton Paul Defiant, Hurricane Mk.I, Spitfire Mk.I fighters, and Fairey Battle light bomber.[70]

  • Merlin X

1,130 hp (840 kW) at 3,000 rpm at 5,250 ft (1,525 m); used in Halifax Mk.I, Wellington Mk.II, and Whitley Mk.V bombers.

  • Merlin XII

1,150 hp (860 kW); fitted with Coffman engine starter; first version to use 70/30% water/glycol coolant rather than 100% glycol. Fitted to Spitfire Mk. II.[69]

  • Merlin XX

1,480 hp (1,105 kW) at 3,000 rpm at 6,000 ft (1,830 m); used in Beaufighter Mk.II and Hurricane Mk.II fighters, Halifax Mk.II and Lancaster Mk.I bombers.

  • Merlin 32

1,645 hp (1,230 kW) at 3,000 rpm at 2,500 ft (760 m); used mainly in Fleet Air Arm aircraft; used in Barracuda Mk.II torpedo bomber and Seafire IIc. Also Hawker Hurricane Mk V and Spitfire P.R Mk XIII.[69] and

  • Merlin 45

1,515 hp (1,130 kW) at 3,000 rpm at 11,000 ft (3,353 m); used in Spitfire Mk.V, PR.Mk.IV and PR.Mk.VII, Seafire Ib and IIc.

  • Merlin 47

1,415 hp (1,055 kW) at 3,000 rpm at 14,000 ft (4,270 m); high-altitude version used in Spitfire H.F Mk VI. Adapted with a Marshall compressor (often called a "blower") to pressurise the cockpit.

  • Merlin 50.M

1,585 hp (1,182 kW) at 3,000 rpm at 3,800 ft (1,160 m); low-altitude version with supercharger impeller "cropped" to 9.5 inches (240 mm) in diameter. Permitted boost was +18 psi (125 kPa gauge; or an absolute pressure of 225 kPa or 2.2 atm) instead of +16 psi (110 kPa gauge; or an absolute pressure of 210 kPa or 2.08 atm) on a normal Merlin 50 engine. A "negative-g" carburettor was fitted.[71][72]

  • Merlin 61

1,565 hp (1,170 kW) at 3,000 rpm at 12,250 ft (3,740 m)1,390 hp (1,035 kW) at 3,000 rpm at 23,500 ft (7,170 m); fitted with a new two-speed two-stage supercharger providing increased power at medium to high altitudes; used in Spitfire F. Mk IX, and P.R.Mk XI.[73] First British production variant to incorporate two-piece cylinder blocks designed by Rolls-Royce for Packard Merlin.[74]

  • Merlin 66

1,720 hp (1,283 kW) at 5,750 ft (1,752 m) using +18 psi boost (124 kPa gauge; or an absolute pressure of 225 kPa or 1.2 atm); low-altitude version of Merlin 61. Fitted with a Bendix-Stromberg anti-g carburettor;[75] used in Spitfire L.F Mk VIII and L.F Mk IX.[71]

  • Merlin 76/77

1,233 hp (920 kW); used in the Westland Welkin high-altitude fighter and some later Spitfire and Mosquito variants. Fitted with a two-speed, two-stage supercharger and a Bendix-Stromberg carburettor. The odd-numbered mark drove a blower for pressurising the cockpit.

  • Merlin 130/131

2,060 hp (1,536 kW); redesigned "slimline" versions for the de Havilland Hornet. Engine modified to decrease frontal area to a minimum and was the first Merlin series to use down-draught induction systems. Coolant pump moved from the bottom of the engine to the starboard side. Two-speed, two-stage supercharger and S.U. injection carburettor. Maximum boost was 25 psi (170 kPa gauge; or an absolute pressure of 270 kPa or 2.7 atm). The Merlin 131 had an additional idler gear in the reduction gear casing allowing "reverse" (left-hand tractor) rotation. The Merlin 130 was fitted in the starboard nacelle, Merlin 131 in the port nacelle on production Hornets.[76]

  • Merlin 133/134

2,030 hp (1,514 kW); derated variants of 130/131 used in Sea Hornet F. Mk. 20, N.F. Mk. 21 and P.R. Mk. 22. Maximum boost was lowered to +18 psi gauge (230 kPa or 2.2 atm absolute).

  • Merlin 266

The prefix "2" indicates engines built by Packard, otherwise as Merlin 66, optimised for low-altitude operation. Fitted to the Spitfire Mk. XVI.[71]

Link to comment
Share on other sites

I'll have to disagree with Dieseltaylor, torque is largely inconsequential. Through gearing, pretty much any kind of torque is achievable - to the point of failure in many cases - whereas (horse)power is limited. And even the power of the engine does not predict everything.

The design of the tanks must take many things into account, and mobility is a very important one. However, mobility is influenced by many parameters. Yes, one needs a powerful engine; the more power, the more speed can be achieved. But in the design of an engine, power is something that has to be traded for other characteristics.

One thing that strikes the eye when comparing engines between the different nationalities, is that the German engines seem to be designed to run forever. They require fine machining, but they have been trimmed perfectly. Loving thought has gone into perfecting even small aspects. It looks like they designed the thing for a tank that would live forever. Partly, this can be explained by the fact that the engine designers did the tank work 'on the side', and mostly worked in the industrial sector. Another might be that Heer specifications on fines and defaults for failing equipment were quite harsh. Until 1944, Germany was not on a war economy.

The Soviet tank engines (plus the rest of the powertrain) look underdesigned in the durability department, in order to squeeze out the extra power. They run rough and hot, with uncompromising vibrational design and primitive lubrication. They will deliver power, they can be maintained by a schoolboy with a spanner, but they will leave you stranded with a totaled engine before long. They are designed to eat themselves up.

It has been a while since I looked at this, so my memory might be fuzzy, but I seem to remember that I found British and American engines quite similar in approach: Take a well-designed normal industrial engine, blow up the proportions and bolt on superchargers. Feed it high-octane fuel, and watch it go. Not as rough as the Soviets, not as perfectionist as the Germans, but solving the problem with liberal application of labour, money and strategic materials.

If all sides would have had each others' engine designs (and they did, as soon as one specimen was captured - reverse engineering engines is not hard), they still would have shrugged and made their own. The Germans had no desire for tank engines that required Western Allies fuel quality, the Russians were not interested in anything that was more complex than strictly necessary, and the Western Allies were in the position that they didn't have to compromise.

As the war progresses, it becomes obvious that all sides learn the lesson that their machines have life expectancies measured in hours. They all start compromising longevity for more power. The more you expect the machine to survive, the less will you compromise its longevity.

Link to comment
Share on other sites

I am impressed you can be so dismissive of torque. I am very aware that with gearing most things are possible. However gearboxes are complicated and the more gears in them the more complicated they become. That is why we do not drive around in 1 litre cars with 10 speed 'boxes though it is coming with 6 and 8 speed boxes becoming available in cars.

They do however suffer from not knowing what gear is optimal and hunting for the right gear in auto-boxes is a problem where software has not necessarily been up to the task. Ford and I believe Lexus have suffered with the problem.

Trucks have had multiple gears for many years because accelerating say 20tons of load from a dead stop to reasonable speed does require much gearing unless one has an enormous engine. Wikipedia says

Power and torque

For commercial uses requiring towing, load carrying and other tractive tasks, diesel engines tend to have better torque characteristics. Diesel engines tend to have their torque peak quite low in their speed range (usually between 1600 and 2000 rpm for a small-capacity unit, lower for a larger engine used in a truck). This provides smoother control over heavy loads when starting from rest, and, crucially, allows the diesel engine to be given higher loads at low speeds than a petrol engine, making them much more economical for these applications." .

Perhaps the author of the piece should add that with sufficient gears torque is not an important trait anyway. However in 1940 multi- [teen]speed gearboxes were probably just a theoretical possibility.

Link to comment
Share on other sites

Diesels have a narrow torque peak at low engine speed. This means that they need many gears to get the load up to speed, but because the peak is at low engine speed, you can take large load masses without burning so much clutch.

The automotive example you quote is about the number of gears available to the motorist, and that is not exactly what I was talking about. The number of gears is more a function of the width of the usable torque curve (how 'supple' an engine is), than of power.

Let me illustrate my point: If you take two engines, that both output P watts of power, but differ in torque at that power, then because P = T * w (power equals torque multiplied by radial speed) the strong torque engine will be running slower. Let us say that engines A and B have the same power, but A has twice the torque. Then if we would mount B in a box with a gear that reduces output revolution speed by a factor 2, their characteristics would be effectively identical. That is the point I was making.

Link to comment
Share on other sites

From JC's post I omitted to mention that the Sherman did have two diesel variants. The Russians were solely supplied with diesel Shermans. They were popular : )

The British had diesel engine versions in the Mediterranean theatre. These ran on twin GM diesels rated at 187bhp - so 374bhp. Again popular as diesel is not as inflammable as petrol - though to be fair it was the Shermans poor ammo storage that got it a bad name., however this was not immediately realised hence the Ronson jokes - and simpler electrics.

The first Shermans were powered by a radial aero engine of 480bhp [note the differnce in power to the diesel equivalent] and according to one site:

"1. The Aeroplane engine is a constant rpm engine. When throttled in a vehicle it tended to backfire whick could be heard for miles."

The Sherman was also powered by five 6 cylinder Chrysler engines mated together - an absolute nightmare to service with the engine needing to be lifted out to be worked on. Amazing that any were ever produced - the saving grace is that they were never shipped out of the US for US use - apart from being given to the British.. ....

Link to comment
Share on other sites

Diesels generally have more torque and were inherently more reliable and robust than petrol engines. This has to do with being built stronger because of higher compression and perhaps most importantly much less electrics to go wrong.

The easiest way to get the high compression for a diesel is to have a higher stroke:bore ratio. Longer stroke gets you longer throws in the crank, which gives the engine better torque characteristics and a lower redline - which means less power. Diesels were built heavier as well, so they generally gave a lesser power:weight ratio than petrol engines.

Link to comment
Share on other sites

Its amazing to think how far the diesel has developed in the last two decades from being a dirty engine suitable only for trucks, ships etc. Now it powers over 50% of new cars in Europe and runs Le Mans winners.

The largest diesel in the world gives 80MW+

The Wärtsilä RT-flex96C is a two-stroke turbocharged low-speed diesel engine manufactured by the Finnish manufacturer Wärtsilä. It is currently considered the largest reciprocating engine in the world, designed for large container ships, running on heavy fuel oil. It stands at (13.5 metres (44 ft)) high, is 27.3 m (90 ft) long, and weighs over 2300 tonnes in its largest 14-cylinder version — producing 109,000 brake horsepower (81.3 MW).

It was put into service in September 2006 aboard the Emma Mærsk.[1] The design is based on the older RTA-96C engine,[2] but revolutionary common rail technology has done away with the traditional camshaft, chain gear, fuel pumps and hydraulic actuators. The result is better performance at low revolutions per minute (rpm), lower fuel consumption, and lower harmful emissions. As of 2008, the power output of the 14 cylinder version has been increased to 84.42 MW (114,800 bhp).

Link to comment
Share on other sites

These guys do a lot on aero engines!!

http://www.ww2aircraft.net/forum/engines/country-designed-best-engines-wwii-8253-6.html

I think at the beginning of the war it was close in aero.

As for truck engines I have trolled through my 400page book on historic military vehicles and there are not huge differences between the truck engine output. The Germans and the US having perhaps more with a larger output - say 10 bhp. But against that remember Ford were building trucks in all three markets!. What is interesting is the huge number of manufacturers and the number that used their own engines. It makes any comparisons probably redundant as over the entire vehicle fleet I have no doubt lemons and good ones existed but all were pressed into use.

Link to comment
Share on other sites

The big advantage teh allies had in the air was high octane petrol.

Given 100/150 octane fuel various aircraft displayed a variety of increased performances, mostly due to bein able to take greater intake pressure boosts - eg the RAF was normally limited to 18lb/sq in, but with 150 could go to 25lb/sq in - which for a Spitfire XIV resulted in

An increase of about 950 ft/min in rate of climb and about 30 mph in all-out level speed....

Not insignificant!

At the start of the war most countries were using 87 octane - the RAF started using 100 Octane in May 1940 (just under teh Engine Power Graph)- giving them anything up to a 34mph boost over their earlier performance in France by allowing boost to 12lb/sq in from 6.5 or 9 lb previously (depending on engine mark).

The use of 100 Octane had been approved as early as 1938, but it took until 1940 to get it in sufficient quantities.

the Soviets loved the extra performance a/c got because of high quality fuel - somewhere (!) I have seen figures that the Sov's were only producing 87 octane befoe the war, and the WAllies supplied about 50% of the USSR's 100 octane fuel - and all the machinery necessary to enable them to refine the othe 50%!

Japanese a/c tested by the allies with 140 octane fuel after the war were up to 60mph faster than they were in their original owners hands....who were only able to provide them with 87 octane.

Link to comment
Share on other sites

Great linky SO, particularly this one

http://www.spitfireperformance.com/spit1vrs109e.html

BTW Credit to Sir Harry Ricardo : ) Man was a genius.

I was mulling over the Corsair HP figures mentioned above and note that the production versions engine were less powerful. I assume that engine longevity and reliability were not achievable with maximum output figures.

[i would also mention that the Corsair was approved by the British Navy for carrier work before it was approved by the US Navy]

It is interesting how much engine output was boosted during the war with octane ratings, superchargers, water injection, nitrous oxide etc. And the flipside of that the limits to preserve the engine for a decent length of time. In the "Night Fighter" autobiography I have just finished reading it is noteable his remarks about engines becoming clapped out allowing fast raiders to dive away to France safely.

A lovely anecdote is late war when RAF and USAAF forces were co-located on East Anglian airfields. The US pilots were very proud of the Lightning and after a disply by a test pilot the Yanks challenged the local Spifire squadron to a "dogfight". With the two pilots up the fight started and within seconds the Spitfire was on the Lightnings tail and could not shake it off.

To gain a degree of pride the US pilot landed on one engine. Tricky for a Spitfire.

"But the British pilot was not to be outdone. As he continued on his circuit around the aerodrome he rollerd over on to his back and flicked his wheels out into landing position. Still upside down he turned to make his final approach to land. At the last moment he neatly rolled back into the normal position just in time to to make a faultless touch-down"

"Night Fighter" by CF Rawnsley and Robert Wright

1957

page 218 Goodall Edition 1998

Looking at Lightnings this viiual autobiography is interesting, the first bit, a memoriam not so but, the third has interesting shots of a Helicoptor and flyingboat.

Link to comment
Share on other sites

I was mulling over the Corsair HP figures mentioned above and note that the production versions engine were less powerful.

I don't know what source you are relying on here, but this one says:

In 1939, when the R-2800 was introduced it was capable of producing 2,000 hp (1,500 kW), for a specific power value of 0.71 hp/in³ (32.6 kW/L). No other air-cooled engine came close to this figure, and even liquid-cooled ones barely matched it. The designing of conventional air-cooled radial engines had become so scientific and systematic by then that the Double Wasp was introduced at a power rating that was not amenable to anything like the developmental power increases that had been common with earlier engines. Nevertheless, in 1941 the power output of production models increased to 2,100 hp (1,600 kW), and to 2,400 hp (1,800 kW) late in the war. However, even more was coaxed from experimental models, with fan-cooled subtypes producing 2,800 hp (2,100 kW), but in general the R-2800 was a rather highly developed powerplant right from the beginning.[2]

Michael

Link to comment
Share on other sites

This site for the R2800 states that they would have a

life in front-line service was unlikely to exceed 50 hours' flying time over a period of only a month or two

I know the early German jets barely made 20 - allied test pilots after teh war were apparently extremely wary of them as they had no way of knowing how long the engines would run for - the later ones were worse as high temperature alloys were in even more short supply in Germanywhen they were buyilt, and the German pilots even worse trained in not overheating them!

Link to comment
Share on other sites

The full sentence in that article reads:

Of course, all engines naturally grow in power with development, but a major war demands the utmost performance from engines fitted to aircraft, whose life in front-line service was unlikely to exceed 50 hours' flying time over a period of only a month or two.

The phrase "all engines" may be read as applying in fact to all military engines and not just the P&W. Most accounts that I have read give high praise to the R-2800 for its reliability including the ability to keep running when entire cylinders were shot away in battle.

Michael

Link to comment
Share on other sites

In the interests of coe I purchased Alfred Price's "Combat Development in World War Two: Fighter Aircraft" published 1976 and 1989. Full of detail I cannot rate it too highly in revealing information prviously unknown to me.

nayone wish to hazard a guess as to the WW2 aircraft most able to approach the speed of sound in a dive? : )

Not incredibly relevant but interesting. He does compare all the major powers front line aircraft in September 1939 and rates the Spitfire I and the Me-109 as close. Nothing else in their league. Anyone wish to hazard a guess as to the fighter throwing the most lead?

Moelders dissed the Spitfire I , perhaps rightly compared to the Me-109, but was shortly thereafter shot down by the MkII - a better plane.

I'll get back to you on the Corsair ME : )

Link to comment
Share on other sites

ME when I used to work on C-47's (briefly in the 70's at the start of my working life) they had a 600 hour overhal life - these were military aircraft at eth time, not civilian ones - I don't know what the life of their engines is currently.

But the "front line life" is not the same as overhaul life - "front line" means you are often boosting it to max and flining it around hte sky in life-threatening manouvres.

So it ends when you get a cylinder shot off.....or a piston rod breaks at maximum boost - well befoer overhaul life!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...