WI The Concorde had Combination Engines ?

[Michel Van]

a Combination engine is Jetengine & Ramjet
the Jetengine push aircraft on speed until the Ramjet takes over and goes supersonic
so wat ? the Concorde hat Olympus 593 Mk 610 afterburning turbojets to get Mach 2.2
yes that true, but Ramjet have one big advance: Reduction of the fuel consumption !

means lower fuel & operating cost or bigger range for Concorde

pushing the range of 3690 to 4079 miles (from 5938 km to 6.564 km)
the Concorde Combination engine can fly over Pacific Ocean: L.A. - Honolulu - Tokyo or Hong Kong

So how would look the Jetset World with a cheaper longrange Concorde ?

P.s the SR-71 used simelar principe with J-58-1 Engine

 

[Geekhis Khan]

I didn't know combo was even an option back then, cool.

I'm curious about cost and maintenance of a combo back then. I know the SR-71 was a maintenance pig, but a lot of that was the hypersonic/high alt stuff. Not sure about the reliability of the engines.

If the "Combocord" here is reliable and not a total maintenance hog then she has a better chance of seeing more than OTL use, but I still wonder about the cost. What limited it OTL was the individual ticket costs which limited its use to the ultra-rich. Could combo engines offset costs enough to make it marketable?

 

[Michel Van]

Irony was
that BAC study in begin 1960's on Combination engine
and France work on simelar projects like Leduc 040 or Griffon 1500 jets

the BAC proposed Engine was differend from J-58-1
the Jetengine is separated from Ramjet (not like J-58-1 were Jetengine was INSIDE Ramjet-tube)
make maintenance a lot easy

also BAC discovert that the Combination Engine could push a aircraft up to mach 7 only with Kerosine
and get even better result with Diesel fuel ! because of it more dence that Jet Fuel
like JP-4 (0.73g/cc) vrs Diesel (0.85g/cc)

a "Combocord" need
JP-4 fuel used by Jetengine only during start and landing
cheap Diesel fuel for the Ramjet !

Environment hazards
Diesel combustion exhaust is a major source of atmospheric soot and fine particles
and the Diesel must be sulfur free

so why we don't have the Combination Engine ?
British Labor party !
after they in came to power in 1964 they start to destory British Aerospace
like BAC TSR-2 cancelled, ELDO Europa-1 and Black Arrow were in danger of
ever british projects were bad and only the U.S. Aerospace was good !
and they almost murder the Concorde
but french imposing heavy penalties in case of a cancellation, saving the plane

 

[Kevin Renner]

Concorde suffered from the same major flaw as the Comet. And no I do not mean the structural one. The airframe was simply too small to allow a large enough passenger capacity. Just my $.02

 

[NothingNow]

Concorde suffered from the same major flaw as the Comet. And no I do not mean the structural one. The airframe was simply too small to allow a large enough passenger capacity. Just my $.02

But the Boeing 2707 isn't as small, and It'd have the same engines probably. Now we have a Working and Viable SST for all those routes. but yeah the Concorde's just too small to be Viable commercially.

 

[Sandman396]

But the Boeing 2707 isn't as small, and It'd have the same engines probably. Now we have a Working and Viable SST for all those routes. but yeah the Concorde's just too small to be Viable commercially.

Concorde's passenger capacity is not the reason it was an economic failure!!!

Concorde was not an economic failure it was a political one.

14 production aircraft is not a large enough run to be viable long term.

 

[daniel_g]

The Boeing 2707 was possibly the cause of Concorde's failure - every Coke needs a Pepsi to make the market!! The Boeing 2707 was a 250 seater, but had a similar range to Concorde. Its achilles heal was that it was designed to fly at just under Mach 3.0, so had to be built from stainless steel, not aluminum. Bristol Aircraft had discovered the perils of stainless steel in their Type 188, so defined the Type 198 (Concorde) to be made of duralumin, and therefore operate below Mach 2.1.

Back to the thread, Bristol Aircraft had full control over the aircraft and engine (until merging the proposal with Sud Aviation). The Olympus was a temperamental engine, but had been in service on the Avro Vulcan since the 1950s; successive increments thrust had also been obtainable. Bristol's BRJ.1-3 ramjets had been successfully flight tested in the early 1950s (under a joint technical agreement with Boeing !!!), and their upscaled ramjet engines lead to the Thor BS.1098 that powered Britain's Bloodhound SAM in service until 1989.

So Bristol had pure ramjet technology and didn't have to go cap in hand to arch rivals Rolls Royce (who had developed combined cycle engines). So why not use a Ramjet? Ramjets generally work between Mach 1.5 and Mach 5.5, with optimum performance in the Mach 2-4 range. A Concorde powered by Bristol ramjets would also need turbojets for sub Mach 2 flight that would be a weight and drag burden under ramjet power. And at Mach 2, Olympus engines had yet to reach their maximum efficiency..

Given the aircraft was designed to be made from duralumin, so limited to Mach 2ish, there was no benefit to using Ramjets.

 

[Michel Van]

The Boeing 2707 had be a Monster of aircraft.
Length: 306 feet (93.27 m)
Wingspan: a swing-wing 105 feet (32.23 m)-180 feet (54.97 m) spread,
liftoff weight: 306 tons
4250 miles (6840 km) with 277 passengers at Mach 2,7

next to High cost to build because use of stainless steel
it had Very high operating cost because the swing-wing mechanic !
see the problem the F-111 had with its swing-wing
and General Electric GE4/J5P turbojets swallow a lot of fuel
in end the operating cost had be bigger as the Concorde

Bristol had in 1958 the Idea for a dubble hull "Concorde" with Combination engine
that twin fuselage can take 240 passengers in theory.

more here note: the page open a pdf
http://www.flightglobal.com/pdfarchive/view/1959/1959 - 1746.html
http://www.flightglobal.com/pdfarchive/view/1959/1959 - 1747.html

 

[NothingNow]

The Boeing 2707 had be a Monster of aircraft.
Length: 306 feet (93.27 m)
Wingspan: a swing-wing 105 feet (32.23 m)-180 feet (54.97 m) spread,
liftoff weight: 306 tons
4250 miles (6840 km) with 277 passengers at Mach 2,7

next to High cost to build because use of stainless steel
it had Very high operating cost because the swing-wing mechanic !
see the problem the F-111 had with its swing-wing
and General Electric GE4/J5P turbojets swallow a lot of fuel
in end the operating cost had be bigger as the Concorde

I was under the Impression that the 2707 was a Delta wing jet setup like the Concorde. I included a (cropped) Picture of the 2707 model that I know of.

 

[daniel_g]

Boeing originally created a VG design to the Concorde specification - the 733. The 2707 was the 250 seat design to the NST committee specification which evolved the design to more of a cranked arrow delta.

 

[NothingNow]

Boeing originally created a VG design to the Concorde specification - the 733. The 2707 was the 250 seat design to the NST committee specification which evolved the design to more of a cranked arrow delta.

That Clarifies it A bit. So yeah When ever I've said 2707 I meant the Dash 300 not the Dash 100.
the 2707-300 seems to be a more viable design than the Concorde and If Boeing had gone through with it they might have been able to develop a Supersonic bomber from it to help with Cash Flow.
I'm thinking that SAC would have loved a bomber capable of Filling in for the B-52 at speeds the B-58 couldn't match. All of that space reserved for passengers in the SST could be used for Fuel Tankage and Nice, Tall bomb-bays.

 

[daniel_g]

the 2707-300 seems to be a more viable design than the Concorde

That's only if you can work out a viable way for a Mach 3 plane not to melt

 

[TheMann]

That's only if you can work out a viable way for a Mach 3 plane not to melt

With these ramjet engines, or a turbofan capable of withstanding Mach 2.5 speeds, you could use stainless steel for the airframe, thus allowing the speed needed. Though you would need to seriously insulate the frame to ensure that the heat didn't get through to the passengers.

I always wondered what air travel woulda looked like today had the 2707 been built and entered service.

 

[Michel Van]

I'm thinking that SAC would have loved a bomber capable of Filling in for the B-52 at speeds the B-58 couldn't match. All of that space reserved for passengers in the SST could be used for Fuel Tankage and Nice, Tall bomb-bays.

the Boeing 733-790 study end up as B-1 Proposal for SAC
as Mach 3 bomber and also as commercial airliner
true mass pruction the building cost had be low
orginal plan was B-1 had to replace the complet B-52 fleed in 1970's

but in end the NAA/Rockwell Proposal made it
irony NAA was the first who drop out of SST Program
one reasion was that SAC wanted a Subsonic Low Altitude Bomber
not a high altiude remake of B-70 Valkyrie

we forgot also another SST
Tupolev Tu-144 ! http://en.wikipedia.org/wiki/Tu-144
its major Disadvantage were the Kuznetsov NK-144 turbofan engines.
they were inefficient and had heavy fuel consumption
wat gave the Tu-144 limited range only of 1600 miles (2500 km)

 

[daniel_g]

Concorde's speed limit was due to kinetic heating, not engine power. The Olympus was still increasing efficiency at Mach 2.2, and interestingly, it operated more efficiently with afterburners (a kind of ramjet anyway) at this speed than without.

Building the planes out of steel was the only feasible solution, however, the aircraft industry changing fabrication from steel to aluminium was as much of a challenge as the automotive industry having spent the last 20 years incorporating aluminium into cars.

p.s. Boeing 773 couldn't have been a mach 3 bomber, it was made of aluminium, but it obviously shares a design ethos with the Rockwell B1

 

[chornedsnorkack]

a Combination engine is Jetengine & Ramjet
the Jetengine push aircraft on speed until the Ramjet takes over and goes supersonic
so wat ? the Concorde hat Olympus 593 Mk 610 afterburning turbojets to get Mach 2.2
yes that true, but Ramjet have one big advance: Reduction of the fuel consumption !

means lower fuel & operating cost or bigger range for Concorde

pushing the range of 3690 to 4079 miles (from 5938 km to 6.564 km)
the Concorde Combination engine can fly over Pacific Ocean: L.A. - Honolulu - Tokyo or Hong Kong

So how would look the Jetset World with a cheaper longrange Concorde ?

P.s the SR-71 used simelar principe with J-58-1 Engine

Not really. The combination jet/ramjet engines are better at Mach 2,7...3 and above, but below that turbojets or bypass turbojets have better range and lower fuel burn.

Lockheed SR-71 actually had combination engines, and Lockheed L-2000 was supposed to have them, too (at Mach 2,7...3). But Valkyrie had GE pure turbojets (and reached Mach 3,08) and B-2707 also was to have pure turbojets.

Concorde suffered from the same major flaw as the Comet. And no I do not mean the structural one. The airframe was simply too small to allow a large enough passenger capacity.

Just the opposite. It was too big. Hard to find 100 people willing to pay the huge price over and above subsonic coach fare.

Maxjet and Silverjet tried to fly 100 seat all business 767s, but they went bankrupt. BA put Airbus 318 on the Concorde flights - with just 32 all business seats. Ordinary subsonic jets may have 400 seats, but under 100 business class seats and even fewer first class - Pan Am started with 58 first class seats on 747, by now business classes are under 100 and first classes are 8 to 16 seats. So maybe they should have built a 32 seat SST to begin with?

That's only if you can work out a viable way for a Mach 3 plane not to melt

Done. Valkyrie. Mach 3,08. Shirtsleeve cabin, unlike that of Blackbird.

 

[Michel Van]

Done. Valkyrie. Mach 3,08. Shirtsleeve cabin, unlike that of Blackbird.

the 2 pilots in SR-71 Blackbird had to wear pressure suits durnig flights

the XB-70 Valkyrie is built largely of stainless steel, and titanium
NAA/Rockwell had very bad suprise trying to bulid the XB-70, like rising costs

SR-71 structure build 85% titanium and 15% composite materials
Lockheed had also bad suprise with first use of titanium or lack of it
No joke: the Titanium neede for SR-71 spyplane came from USSR !
the Boeing-2707 had also to build from stainless steel and titanium
Titanium mostly as part of aircraft wat became very hot at Mach 2.7
also this Titanium has to come from USSR

to passenger capacity on Aircraft
the Boeing 747 push commercial airliner to new dimension in 1970
with 452 passenger makes 747 flights economically
and push smal passenger capacity aircraft like 767's of Maxjet and Silverjet in problems.

but SST is a another League
SST is for VIP and business class, who need get fast over the Ocean
and wandet to pay that high ticket price, OTL that happen in 1980 and save the Concorde
exsampel:
from London Heathrow to New York JFK
with Concorde in 2 hours, 52 minutes
with Boeing 747 in 8 hours, 5 minutes
so you need to get fast to New York, wat you gona take ?
i think the name of Aircraft start with C...

 

[Dathi THorfinnsson]

from London Heathrow to New York JFK
with Concorde in 2 hours, 52 minutes
with Boeing 747 in 8 hours, 5 minutes
so you need to get fast to New York, wat you gona take ?
i think the name of Aircraft start with C...

That 2 hours 52 minutes AND 59 SECONDS was a record.

usual flight time was 3 hours 30 minutes, apparently.


If cost were no object, then, ja sure you'd take the Concorde. But the Concorde was MORE expensive than first class, and as other people have pointed out, no one has yet made a profit with a 100+ passenger jet in an all 1st class configuration.

 

[Riain]

I was under the impression that once the airlines had figured out what to do with their Concordes they were quite profitable.

 

[Dathi THorfinnsson]

I was under the impression that once the airlines had figured out what to do with their Concordes they were quite profitable.

IIRC, they covered operating expenses, but not even so much as the interest on the purchase price, let alone the development cost....