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Yes and no.
Yes there were a number of overnight sleeper operations and yes the DC-3 started as the DST but as a percentage of the total airline fleet do not think that these aircraft were that significant a percentage of total fleet hours. I could be wrong of course. I would also add that long before the sleeper services started the majority of mail and some freight flew at night. Again as a percentage of the whole I believe that this was not that significant.
And yes engines were swapped out, not overhauled while the aircraft sat around idle. That is why I said that aircraft were doing some 2000 hours per year and engines up to 1500. Depending on the engine an operator would hold 30-100% spares for this reason (making my estimation of about 1500 way too high). Many operators did their own engine and component overhauls as depending on the manufacturer could result in your engines being held up in overhaul by brand X's engines so having your own shop guaranteed your engines got priority and were done the way you wanted.
Ten hours non stop for a DC-3 sounds like they were pushing the limit somewhat as my (very fallible) memory is that the DC-3 did not have that endurance. I will have to check.
EDIT - According to the USAAF C-47 flight manual the C-47 had an endurance of 11.82 hours if you made no allowances for take off and climb so that does make 10 hour flight possible but they would definitely be running on the smell of an oily rag on landing and have nothing in reserve. I suspect the earlier engines were a little less fuel efficient than the 1830-92 which would have shortened the range a little as well. I cannot find my DC-2 flight manual.
Cruising altitude was 1500ft.
That 11.82 hours is based on the minimum specific fuel consumption rate 34 gph at 450hp. This is neither the minimum fuel consumption to maintain level flight nor the power for best range.
Hawker Typhoon. Fix the tail at the onset, get a reliable and mass produced Sabre or Centaurus engine into the Typhoon by end 1940. Send four squadrons to Malaya in early 1941, eight more by October 1941.
Fair enough. Then let's just fix the tail. That surely meets the criteria of this thread.Centaurus production started in 1942 so it would be difficult to send four squadrons to Malaya in early 1941, eight more by October 1941.
And yes I do know it first ran in 1938 but is was not produced until 1942 because Bristol needed to improve the reliability of their entire sleeve valve engine line and it did not make it into any ww2 aircraft
I see what you mean, but this vertical windshield and all these protrusions near the engine, under the wings and fuselage plus that tail wheel must rob some speed. I'm no aerodynamicist, but there's probably another 20-30 mph in top speed easy here.Once could argue that Skua was far more streamlined than Ju-87 or Aichi Val - retractable U/C vs. fixed, and no 'dropped' flaps like the Ju 87 had. Where it lacked was 'under the hood', 900 HP is not going to enable much more than it was historically so.
I see what you mean, but this vertical windshield and all these protrusions near the engine, under the wings and fuselage plus that tail wheel must rob some speed. I'm no aerodynamicist, but there's probably another 20-30 mph in top speed easy here.
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There was some glide-bombing requirement. I've bought a book or two on this and there was no real clear answer, Eric M. Brown's book on the Luftwaffe's aircraft also seemed to bear no useful information except that the dive requirements were increased to 60-degrees after the Spanish Civil War. Maybe there's a source with more detail out there, but I haven't been able to find it.I can't remember if the He 177 was originally proposed and designed without provision for dive bombing, but the requirement for dive bombing was added later causing delays and structural issues.
They wanted to fly to the Urals and back right? That's a round trip of something like 3500 miles from Berlin. From what I recall, they wanted a speed of 500 kph, a provision for shallow/moderate glide-bombing capability pretty early on, not sure what cruise altitude they wanted. They seemed really fixated on having two props over four. I know it was based on installation drag, but it was all of 3%. Now that's significant at speeds in the 300 mph range, but they were planning to use surface evaporative cooling which would greatly improve climb performance, and lower overall drag. The landing-gear would have been easier to work out if the propellers weren't so large.The He177 was purely conceived as a strategic heavy bomber in answer to the RLM's "Bomber A" program, which would have seen it penetrate into Soviet airspace to strike industrial targets.
The Grief was an answer to the "Bomber A" program after the "Ural Bomber" request produced few results. It had impressive range with a light bomb load, but like most heavy bombers, it's range was drastically reduced if it carried it's max. load of 15,000 pounds.They wanted to fly to the Urals and back right? That's a round trip of something like 3500 miles from Berlin. From what I recall, they wanted a speed of 500 kph, a provision for shallow/moderate glide-bombing capability pretty early on, not sure what cruise altitude they wanted. They seemed really fixated on having two props over four. I know it was based on installation drag, but it was all of 3%. Now that's significant at speeds in the 300 mph range, but they were planning to use surface evaporative cooling which would greatly improve climb performance, and lower overall drag. The landing-gear would have been easier to work out if the propellers weren't so large.
Do you have any data that indicates the specs that were dictated? Speed, altitude, range, payload over range, maximum payload, etc...The Grief was an answer to the "Bomber A" program after the "Ural Bomber" request produced few results. It had impressive range with a light bomb load, but like most heavy bombers, it's range was drastically reduced if it carried it's max. load of 15,000 pounds.
Yeah, the ironic problem was that, the fires were caused by the requirements for dive-bombing: It had to do with flexing of the engine nacelle (which resulted in a shorter nacelle shoved further back in the wing), a poorly designed oil pump, and other issues which I think had to do with the position of the electrical harnesses.The major issue Heinkel had, was the engines overheating and subsequent fires, just like the US had with the B-29.
Agreed. They were fixated on the idea to the point of stupidity. It made sense for the Ju-87 to have this capability. One could even argue modifying a Do-17 to do it. It's getting a bit silly with the Ju-88, and by the He-177, it was fucking nuts.The "glide bombing" doctrine hampered development
They would have needed serious creativity, and probably would have produced an overweight clunk that would have climbed considerably slower, and had a substantially shorter range that would have probably seen it useless in the intended role.Imagine the USAAC requiring the B-17 to have the same requirement and how long it would have taken Boeing to make it happen...
1. Regarding the Hyper Engine: From what I remember, it would have been possible for the USAAC to have simply changed the contract terms for the V-1008 to the IV-1430 from single cylinder to mono-block to single-cylinder at any point in time. Would that have been a good idea to have done so?
As for two valves per cylinder: The first development of four-valves per cylinder in a reciprocating engine was in 1916. I'm not sure when it first appeared in aircraft-engines, though it seemed to be there in the 1930's.
Actually, from what I remember the first design was 1008 cubic inches, and a V-inline. Would the money pooled up for the project have sunk us?wuzak said:Yes, of course they could. But that would involve more design and cost.
Also, there was never a V-1008 - that was always going to be the O-1008.
I didn't know that actually...The 1912 Peugeot L76 Grand Prix car had dual overhead camshafts and 4 valves per cylinder. It won Grands Prix and also the 1913 Indianapolis 500.
While this comes from wikipedia *ducks*, it happens to match things I've heard said on this forum, though I can probably sift through this forum and find much of the same thing.Sam Heron, head of development at Wright Field and a former colleague of Ricardo while Heron had been working at the Royal Aircraft Factory, Farnborough, started working on the problem with a single-cylinder test engine that he converted to liquid cooling, using a Liberty L-12 engine cylinder. He pushed the power to 480 psi Brake Mean Effective Pressure, and the coolant temperature to 300 °F (149 °C) before reaching the magic numbers. By 1932, the USAAC's encouraging efforts led the Army to sign a development contract with Continental Motors Company for the continued development of the engine design. The contract limited Continental's role to construction and testing, leaving the actual engineering development to the Army.
Starting with the L-12-cylinder, they decreased the stroke from 7 in to 5 in in order to allow higher engine speeds, and then decreased the bore from 5 in to 4.62 in, creating the 84 in³ cylinder. This would be used in a V-12 engine of 1008 in³ displacement. They used the L-12's overhead camshaft to operate multiple valves of smaller size, which would improve charging and scavenging efficiency. Continental's first test engine, the single-cylinder Hyper No.1, first ran in 1933.
They eventually determined that exhaust valves could run cooler when a hollow core filled with sodium is used — the sodium liquefies and considerably increases the heat transfer from the valve's head to its stem and then to the relatively cooler cylinder head where the liquid coolant picks it up.
Liquid cooling systems at that time used plain water, which limited operating temperatures to about 180 °F (82 °C). The engineers proposed using ethylene glycol, which would allow temperatures up to 280 °F. At first they proposed using 100% glycol, but there was little improvement due to the lower specific heat of the glycol (about 2/3 that of water). They eventually determined that a 50/50 mixture (by volume) of water and glycol provided optimal heat removal.