LoonyBob

The GE Turbo-SUpercharger used in the P-47, used an axial-flow turbine; so turbine blade growth would have been the life-limiting factor. The TIT - turbine inlet temperature - is crucial to controlling turbine aging*; the lower, the better. The long pipework would very much help limit the maximum TIT. Just to confuse things, superalloy growth rates under constant stress at constant temperature are not linear, particularly in the first 20~200 hours. At its best (jet engine) operating temperature, NiMoNic 75(?) blades actually shrink for about 80 hours, then take another ~~70hrs to grow back to its original length. NiMoNic 60 doesn't shrink to speak of, but holds constant for a few tens of hours. Both are stretching like taffy at 600~750hrs... in a turbocharger, which does have lower TIT than a jet, they should last thousands of hours, subject to usage, manufacture, and salt exposure. I have NO idea what superalloy GE used at the time. In engineering terms, heat is energy and energy is heat. A radial inflow turbine - as used in small turbos for cars etc - gets its energy from the gas velocity, the gas inertia, and a slight bonus from the exhaust pulses. Back pressure is created only by the flow losses through the tortuous guts of the thing; but as the drive comes mainly from inertia, not dynamic pressure (Pelton wheel style), the secondary losses are quite large. An axial turbine gets its energy from the gas velocity, like a propeller in reverse, and the only losses to speak of are frictional. Perhaps the most accurate enginge heat breakdown in the public domain was for the Merlin, of which 25% of the heat in the fuel went out the crankshaft and twirled things; ~50% went out the exhaust pipe... modern cars do about the same under acceleration, so there's plenty of free heat - one just adds an amount of boost equal to any turbine-induced back pressure, and everything else the turbo gives is free. A centrifugal compressor cannot achieve much better than 70~ adiabatic efficiency, because the air entering the eye is not rotating, but the "channels" between the vanes are. That means that ~30% of the drive energy (or more when outside the optimum mass flow/pressure ratio "island") is heating the air; which is great at causing detonation destruction and mechanical death for spark ignition engines. Thus, "pre-cooling" or "intercooling". Interestingly, adding a supercharger and lowering the compression ratio will give a higher (maximum) power to weight than just bumping up the compression ratio, with a greater margin of safety from detonation to boot. One may then disregard intercooling for low boosts, as seen on many/most inter-war aero engines. An axial-flow compressor achieves >96% adiabatic efficiency, thus heating the air charge very little, as seen on DB601s and peers. <> The Hun in the Sun was a sound practice in WW1, but the "attack from above" has more complex reasons. Imagine two fighters in a level(ish) turning duel; the faster the following fighter goes, the larger the turn radius, the prey gets away - but slow down or bleed energy, and the prey gets away! However, if the attacker rolls level whilst maintaining the same G, a 1/4 of a turn sees the vector near-vertically up and curving in towards the far side of the circle of pursuit, ahead of the target (deflection, woo hoo!). Also, in the arc over the top, the wings are unloaded, so induced drag almost vanishes - an energy advantage! Shoot down target, rinse and repeat. This tactic - which dates from Boelke - was the reason the Bfs and Fws were designed to have a better initial climb gradient / "zoom' climb than the Allied fighters of the time.

First, the engines: The fixed-speed geared superchargers the UK started the war with, could not be used on takeoff or the donk would destroy itself; they had one optimum altitude, and fell off above it. The two-speed superchargers did the same, but twice... The Bf & FW supercharged engines could run optimum boost at any altitude up to ~22,000ft (later they used larger compressors, to go higher); but the supercharger was not at its own best efficiency most of the time. The US toyed with Turbochargers, which have built-in altitude compensation up to some ceiling, though not peak efficiency all the way up. But airframes!: The thick wing on the P-38 and Typhoon limited them to below ~14,000ft iff'n they wanted to run with the pack. Anything using thinner turbulent (non-laminar) airfoils - Bf109, Spitfire below Mk.21, Grumman fighters, P-47s, Mossies - had a higher rate of climb and smaller turning radius (ok, except for the P-47 & Mossie!) than the P-51D, and some were faster; but above ~25,000ft, the Mustang was faster and outclimbed anything I've listed so far. I have not seen the outcomes of any flt-off between a P-51D, a Yak-3, and a Hawker Tempest/Fury (granted, the Hawkers were a generation ahead of the Stang). The Me163 and 262 were pretty good at high altitude, but the later 109's were weighed down with anti-bomber ordinance... My summary understanding was that the Luftwaffe had the edge at very high altitudes (in fighter terms), until the 'stang came along. The P-47 was not great from compressibility, but had the power and tankage to be up there with the bomber swarm, and the 8 .50 cals made an impression. From memory, Clousterman wrote of an ocassion when he was stooging around Germany in a Tempest at ~4,000ft, looking for landing 262's to molest, when "for some reason i glanced in my mirror... three FW190s were following me, the Nitrous Oxide turning their exhausts white-hot" (the Gremans had fitted FW190s with NOx to try and catch the Tempests); Clousterman applied WEP and simply flew away from them... not high altitude of course, but it thinne dout the 262s.

The DB601 & 605 used a fluid coupling for their superchargers, and varied the compressor speed by adjusting the fluid level on the fly... the max boost was limited only by the design & "trim" of the compressors. As Nev says, superchargers care not about heat. To my mind, the JUMO 004 using hollow turbine blades welded from arcs of tubular steel was a more significant indicator of the lack of superalloys...

Mittagong - Crookwell - Rylstone, then wherever. Landable all the way, if you don't go north of Wedderburn or The Oaks... I don't much like the hop over Brooklyn Bridge to Warnervale, even if you make it over the golf clubs of Greater Sydney...

The very early ones used rolling element bearings, as did Whittle, and far too many WW2-era piston engines; I'd think it probably the Corncob turbine did too. Smaller turbos certainly used plain bearings post-WW2, until McInnes invented his clever floating bush (late '60s? early '70s? of course it took a while to get universal...). I'd expect any form of bearing to coke up from heatsoak, in a turbo... I hear youse bragging about jets, but they too get sparkplug problems! Well, some of them...

It is a nice looking aircraft... is the Hobbs saying 111? The ASI suggests 90kt Vno...

They walked away, more or less! Isn't that the way the Code Napoleon works? Guily until proven innocent? maybe I lack Gallic Insouciance...

Good point, but a pilot can be nice to them... the Super Connie engines had the exhaust turbines geared back to the crankshaft - it's called a Compound engine, wherein two or more stages of expansion are compounded to extract the power - and the supercharger ditto. All the pilot has to do is limit the manifold pressure on takeoff. The larger problem with that engine is aggressive leaning; they ran them so lean the EGTs dropped, with the side effect of eating plugs, valves, and turbines (they used to watch every plug's voltage spike on a CRO in flight, and note the failed plugs to have them changed during refeulling...).

DAMEs - and the AMA - tend to be pretty conservative; without appropriate legislative guidelines, they tend to say "no"... aside from the legendary Helsinki Study, statistical analysis of the regulation of medical conditions is scanty, and based upon poor sample sizes. Wanna crowdfund an exhaustive literature search and analysis of probabilities, to determine levels of safety in ICAO terms?

😂 Politicians decide where the public funding goes. Please name all Aussie federal politicians since Federation (barry Jones) to hold a science degree? (Barry jones). Of course the challenges involved in designing and building a functional and "as safe sa practicable" reactor attract some of the best and brightest. That does not mean that they question the fundamental presumptions; they are modelling in atheir own respective closed systems. How long before the known negatives of asbestos, found by science, were accepted by Politicians? And how much longer, by James Hardy? Were the people responsible for the Manhattan Project stupid, or poor scientists? I think not; yet was their achievement an unmixed blessing? Ask the Downwinders... Simplistic logical fallacies do not help the debate. Argumentum ad Populum is a logicasl fallacy.

Most elevated distribution cables use aluminium, which is widely available in mud...

Peer pressure, eh? I prefer the science, the whole science, and nothing but the science...

The pilots are very careful to keep the TIT down... when's the last time anyone heard a restored as original warbird on full boost?

They are designed by FEM, to optimise their "Hgh-Cycle Fatigue Life"; and for optimum aerodynamic twist. As they are retired from fatigue issues, they are only useable in a non-fatigue environment, such as a compression member on a bridge. However, they are entirely the wrong shape for that - squat and cylindrical is the go! Perhaps they could be chewed up and used as filler for composite beams... but the work on non-cementitious cements (I kid you not!) by Wagner makes that less economically attractive...

Not good news, really.

What kind of negative thinking is this? Have a gander at the below "aircraft" donk...

The original 95:10 weight limit of 400lb MTOW was judged to be the maximum weight that would not retain velocity on passing through a tiled roof... this is a great precedent for an energy argument, which the heavy Vehicle license equivalent ties into. If it is deemed an acceptable risk to the public to drive a road-train full of petrol, then an aeroplane having a kinetic energy euivalent to the total energy of said truck is also acceptable, with the same level of training and medical. Sorry, shouldn't use logic... I wonder if CASA have yet acknowledged that "General Aviation" is no longer a pool of reserve pilots for the RAF in event of WW2 breaking out?

I know the average life of a Spit was ~37hrs, and 5~7hrs during the BoB. 6 minutes combat? The Lancaster (Manchester) requirement was supposed to specify a 30-hour life; the B-24 had a - yes - 24hr designed life, which meant most of them were timex after the ferry flight to the UK.

"8 Establishment of CASA (1) An authority called the Civil Aviation Safety Authority is established by this subsection. (2) CASA: (a) is a body corporate with perpetual succession; (b) shall have a seal; and (c) may sue and be sued in its corporate name." The part I have bolded is the reason CASA is grossly reluctant to expose itself to any risk. This clause is unique to Australia, and was introduced under Keating as part of NeoLiberalism (2.0) disguised as economic rationalism. It is questionable whether Australia should retain its authority as an ICAO signatory, when its Aviation Authority is nobbled...

"9 CASA’s functions (1) CASA has the function of conducting the safety regulation of the following, in accordance with this Act and the regulations: (a) civil air operations in Australian territory;" CASA are responsible under the Act, full stop.

Dunno about the P47, but the Piper twins use John Deere parts, washed through a heightened QC process. I did a few APMAs for parts, yonks ago.

Britten blended a leading double-arm linkage suspension, which gave phenomenal cornering speeds and outstanding braking, with a composite frame and an engine of his own design. A generation ahead of anything else on two wheels...

Oh, them thangs... yer missed the word "economically". A process about as complex as oil refining is needed to discombobulate the aged resin without poisoning the scenery, as Nev mentions; but it can certainly be done. Are all the industrial chemists on holidays? A brute force approabing, is to oxidise the monsters at elevated temperature, which separates the matrix (resin) from the carbon fibre, but is likely to atrophy said carbon fibre. If done in a "bomb", said gases can then be scrubbed*, hydrolysed, and alkylated, or otherwise molested into a useful form. There WILL be an energy cost... *Nope, dunno what form of scrubbing, would have to study the chemistry closely...

Just burn 'em, then extraxt the carbon from the smoke...

From the Chicago Convention of 1922 to the Chicago Convention of 1944, it was hammered out that Airworthiness is defined in terms of "Acceptable Probability of Failure", and that Airworthiness is achieved by: Control of Design; Control of Manufacture; Control of Maintenance; Control of Operations; and Control of Training. Your argument is economic; your position is that you bought the engine, you don't want to spend significant money on it until the TBO is reached. Bad luck; the engines for London Buses were designed that way; but that is NOT how safety is achieved in aircraft that are light enough to fly. It boils down to the physics of flight; there would be no turboprops if empty weight / MTOW ratio were not the penultimate expression of aircraft effectiveness....