Everything you always wanted to ask...

[Geoff]

yep that sounds right.

[John Howling Mouse]

Side-by-side ejection seats (i.e. A-37 or Tutors, etc.).

1. Will only one seat eject if it is triggered?  I would not want to be sitting that close to one going off beside me and passing my face on the way up!

2. Are they designed to always fire staggered, regardless of which pilot triggers them at what time or can the two actually fire up the rails simultaneously?

I have checked on the Ejection Seat Site but it feels like you'd have to know which article (if any) covers this sort of thing in order to find such details.

http://www.ejectionsite.com/

[gooberliberation]

Why were air-cooled radial engines supposedly better at low altitudes than inlines/vees and vice versa?

[GTX]

I believe the main advantage of air-cooled radials over liquid cooled inlines/vees at low altitudes was mostly to do with their reduced vulnerability to ground fire - i.e. the liquid cooled engines could receive damage (from ground fire etc) to their radiators that would result in the engine over-heating.  There are numerous cases of radial engined P-47s and Fw-190s returning with entire engine cylinders shot out.

Regards,

Greg

[ysi_maniac]

Is it possible to have a GB without competition? I mean, just a SIG.

Can a SIG have a devoted subforum?

Thanks,
Carlos.

[Hobbes]

Why were air-cooled radial engines supposedly better at low altitudes than inlines/vees and vice versa?

In addition to the damage resistance GTX mentioned:

ISTR the radials used early in WW2 were naturally aspirated so they lost power at high altitudes. Inline engines often used turbochargers or superchargers which mitigate this.
Radials are harder to add turbo/superchargers to, for a few reasons:
- more complex plumbing
- air cooling means there's a fairly low limit to the boost pressure you can run (more boost=more heat than the cooling system can handle)

[ysi_maniac]

But P-47 was turbocharged-pistonengined  

[RP1]

RAF pilots cottoned on to this trick, and used it at Red Flag (IIRC)

Offhand, I think it was Sharkey Ward in Sea Harriers - they knew the settings used on the F-15's radars and so could force them into a low speed dogfight where the Harrier held the advantage.  IIRC, he says this gave him confidence in their ability to handle Mirages over the Falklands.

Of course, Ward's word should, apparently, sometimes be taken with a pinch of salt...

RP1

[jcf]

ISTR the radials used early in WW2 were naturally aspirated so they lost power at high altitudes. Inline engines often used turbochargers or superchargers which mitigate this.
Radials are harder to add turbo/superchargers to, for a few reasons:
- more complex plumbing
- air cooling means there's a fairly low limit to the boost pressure you can run (more boost=more heat than the cooling system can handle)

The majority of radial engines used throughout WWII had engine driven superchargers, aside from training aircraft, I don't believe any of the combatants used a naturally aspirated radial on a mainline aircraft. The less powerful ones were single stage, the more effective engines used a two-stage supercharger.

Adding a turbo-supercharger to a radial is just as 'easy' as adding one to an inline engine, the plumbing is no more complex. The B-17 and B-24 both had turbochargers, the B-29 also used turbochargers.
Mechanical superchargers were built right into the engines, they were an integral component.



The yellow painted area on this cutaway Hercules is the supercharger section. This a single-speed, single stage engine, other series Hercules had two-speed, two-stage superchargers.

Jon

[anthonyp]

Is it possible to have a GB without competition? I mean, just a SIG.

Yes.  But where's the fun in that  

Just kidding.  Some of the earlier ones on the site were held without prizes (The GLORIOUS Soviet Carrier Ops build was done for the betterment of Rodina, and Workers' Pride!  ZA RODINA!!!!).

[Shasper]

What is this thread here for?    


Ok, in all seriousness, what's the reasoning behind the tri-jet arrangement like on the 727 & the Dc-10/MD-11 ?


Shas B)

[Iranian F-14A]

Shas,the main reason was the fuel crisis of the 1970s,when those aircraft were designed.At the time,the alternative,for the most part,were 4 engined designs,namely the 707 and DC-8.The idea was to burn less fuel(3 engines opposed to four) and carry more passengers.The 727 also used the same body(although shortened) as the 707,just new tail and wings.Theres the short anwser.I'm sure someone could add to that.EDIT: Boeing also came up with a triengine 747 proposel for the same basic idea,fuel conservation.(and to compete with the L1011 and DC-10)


My question was about the U-2.When U-2s were being operated in the UK back in the days of the original models,not the more recent U-2R/S or TR-1 models,they were first flown in the standard black colors.Apparently,due to reactions from the british people,and possibly the goverment,the USAF/CIA changed the colors to the "Sabre Scheme"(as I've heard it described) which was like a 2 tone blue or grey.So,what issue did the English have at that point with Black painted U-2s?

[jcf]

Two different tri-engine setups with different histories.

The Trident/727 type three in the tail configuration dates from the late 1950s, long before the fuel crises of the 1970s, and was basically an extension of the Caravelle concept of rear-mounted engines.

The tri-jet wide body DC-10/L1011, two on the wings-one in the tail, arrangement dates from the latter half of the 1960s. Both aircraft grew out of a 1966 request from American Airlines for a new wide-bodied, 250 passenger, twin-engine aircraft. The third engine was added by both teams because of customer concerns over performance in marginal conditions... high and hot or long-range over water flights etc.

Both aircraft flew and were in production before the fuel crises of the 1970s.

The fuel crisis had far more effect on the designs of the 757/767 and Airbus aircraft. One of the original 767 proposals was a near-supersonic, wasp-waisted four engine aircraft with highly swept wings. The engine installation was interesting, one on each wing and two on the rear fuselage ala the Caravelle. The oil embargo and the rapid increase in fuel cost, from 11 cents a gallon to $1.10 a gallon in very short order, was the death knell for the high-speed design and Boeing went back to the drawing board.

Jon

[Daryl J.]

Why does kit customization thrill an automotive modeler, yet bring a typical aircraft modeler into full apoplexy?              

    ,
Daryl J., who's never built any kit to 'stock' form, ever, save for one Tuskegee P-51 built for one of their own.  

[deathjester]

Side-by-side ejection seats (i.e. A-37 or Tutors, etc.).

1. Will only one seat eject if it is triggered?  I would not want to be sitting that close to one going off beside me and passing my face on the way up!

2. Are they designed to always fire staggered, regardless of which pilot triggers them at what time or can the two actually fire up the rails simultaneously?

I have checked on the Ejection Seat Site but it feels like you'd have to know which article (if any) covers this sort of thing in order to find such details.

http://www.ejectionsite.com/

Normally, yanking on the 'ole yellow 'n black handle starts an ejection 'sequence', ejecting one, then the other crewman.  On some aircrft, you can select which seat fires, but usually pulling one handle would fire both seats.  I agree, not something you'd normally want going off next to you, but infinitly preferable to the alternative....besides which, the seats rocket doesn't fire instantly - that has been proven to have a somewhat debilitating effect on one's spine - an explosive chare fires first to blow you out of the cockpit, then the rocket fires as a sustainer to maintain your velocity.