Modern day, I don't know... but here's some designs from the past...
(The RM-2 is essentially a DH Ghost Mk 50 -- same engine as the Comet's)
It was a centrifugal-flow jet developed by De Havilland itself, originally for the purpose of powering a Swedish-Fighter design, the Saab Tunnan, and ended up being used as the first powerplant for the De Havilland D.H.-106 Comet 1 -- the worlds first production jet-airliner.
Technically, by the time the DH
Comet first flew more powerful axial-flow jets such as the Armstrong/Siddely Sapphire and Rolls-Royce Avon engines did exist, but they were virtually brand-new and they were being used exclusively for military purposes (either because the engine had not been released for civilian applications, or because military needs were so great)
at the time, forcing De Havilland to make due with the DH
The engine produced approximately 5,000 lbs of thrust by the time it first flew with the De-Havilland Comet. Considering the Comet 1 weighed 105,000 lbs (later increased to 107,000 lbs)
, and the heavier Comet 1A (which carried extra fuel)
weighing in at 110,000 lbs (later increased to 115,000 lbs)
the thrust to weight ratio was not impressive resulting in rather flat-climbs although the airplane could perform takeoffs and landings in approximately the same distance as a very large piston-powered airliner due to it's huge wings, light wing-loading, and (by modern standards)
relatively low takeoff, and landing-speeds.
Since the Comets had serious structural design deficiencies (the plane blew up in mid-air twice due to explosive de-compression)
, the fuselage had to be strengthened (and fitted with re-designed windows)
, which added at least two-thousand extra pounds of weight to the Comet 1 design (which by now were upgraded to 1A's, with the extra weight taking the plane up to 117,000 lbs)
, which was now known as the Comet 1XB. This particular variant was powered by a more powerful variant of the Ghost which went up to 6,000 lbs, which actually more than offset the weight increase. Unfortunately, it only increased the service live to 20,000 hrs (not to mention by this point, at least one of the Comet operators scrapped their Comet 1's)
It was the to the best of my knowledge the second axial-flow turbojet built (The Armstrong-Siddely Sapphire was the first if I recall-correctly)
being run up for the first time during the late 1940's.
The first civilian airplane the engine ended up powering were growth variants of the DeHavilland DH
-106 Comet -- the Comet 2 and Comet 3. Since the Avon was shaped differently than the Ghost, had a different diameter, and different airflow requirements, all of these new Comet-variants featured re-designed intakes, and engine-bays to accomodate this engine. Either due to the RR
Avon being louder than the DH
Ghost, or due to noise-regulations (or a simple desire to reduce noise)
these airplanes also featured cookie-cutter type sound-suppressors, which also used some entrained air to enhance the effectiveness of sound-suppression (although the RR Avon was not quiet by any means, and it produced an awful, shrill, high-pitched noise)
The Comet 2, design-wise was closest to the Comet 1, with only a small stretch in the fuselage, necessary modifications to accomodate the Avons, and a revised wing with increased camber to improve low-speed performance. The airplane carried the same fuel capacity as the Comet 1A, with an increased payload and maximum takeoff-weight (120,000 lbs)
. Even though the particular Avon variant used on the Comet 2 were not particularly powerful (7,300 lbf apiece)
, it was still substantially greater than the DH
Ghost, with overall thrust increased 50%. The airplane's thrust to weight ratio was drastically improved (although by today's standards, they would be considered poor)
allowing shorter takeoff-runs, and improved climb-performance. The plane made it's first flight in August, 1953
The Comet 3 was stretched considerably, featured enlarged wings with streamlined bullet-shaped pinion-tanks to further increase fuel-capacity and range, and featured a revision to the exhaust nozzles moving them slightly outboard to reduce sonic-fatigue. The larger fuselage, wings, fuel and payload all ended up increasing the maximum takeoff weight to 145,000 lbs. Despite the weight gain, more powerful RR
Avons with thrust-levels in the 11,000 lbf class, and to an extent the larger-wings more than helped compensate for this. The aircraft made it's first flight in July, 1954.
Due to two mid-air structural-failures involving Comets, the fleet ended up being grounded, and public-confidence in the Comet waned, airlines that were planning on ordering Comet 2's and 3's pretty much dropped all their orders. Over a roughly four-year period, the Comet disasters were investigated, solved, and new requirements were made based on findings to meet safety requirements, including a sturdier, heavier skin, ovalized windows (to my knowledge they came in two sizes -- the larger size came with metallic rip-stoppers around them to prevent fatigue cracks from spreading)
, and structural modifications.
During this time, the RAF bought the Comet 2's which were already built, fitted them with 11,000 lbf thrust RR
Avons, and over the course of two modifications, increased the service-life of the airplane. They used them as transports.
The Comet 3 was a one-of-a-kind plane. It ended up being modified as a prototype for the Comet 4, which was the same size, but had all the new structural modifications, allowing it to be operated safely with a long service-life. While the design was now up to 162,000 lbs, the thrust to weight ratio was still reasonable (although takeoff and landing speeds were now higher)
. The Comet 4 also came in two stretched variants -- the 4B and 4C
which featured equal fuselage lengths, with the 4B featuring a shortened wing, and the 4C
featuring the regular 4's wing. To my knowledge, at least the 4B featured thrust-reversers on the number 1 and 4 engines (technically the Comet 2's used by the RAF also were fitted with number 1 and 4 thrust reversers IIRC)
The second civilian-airplane to be Avon-powered was the SUD Aviation SE
-210 Caravelle, which was a dedicated short/medium-range jetliner with rear-mounted engines to reduce sonic-fatigue, and un-clutter the wings, improving aerodynamic performance (which was further enhanced by the large wing-area and substantial flaps)
. Since it would have to be able to slow down quickly as well as speed-up, the airplane featured speed-brakes.
While later versions of the Caravelles would adopt turbofans, (Such as the Caravelle VII concept, Caravelle 10A, 10B, 10R, 11R, and Caravelle 12)
the Caravelle I (prototype)
, Caravelle IA
, Caravelle III, Caravelle VIN, and VIR
are all turbojet examples. The Caravelle IA
, III, VIN, and VIR
's all are the same lengths with the differences between the first 2 being engine power and weights, with the VIN also having revised speed-brakes, and the VIR
having a redesigned cockpit and thrust-reversers (which was used by United Airlines)
Pratt & Whitney J-57 / JT
It is the first twin-spool axial-flow turbojet to enter mass-production -- it started out as a straight turboprop (no reduction-gear)
called the T-45 during the very early preliminary stages of the B-52 program, when they were uncertain whether to go with a turboprop, or a turbojet, and then evolved into a pure-jet design.
The first civilian-plane to be powered by the J-57 was the Boeing 367-80, which doubled as a proof-of-concept for a jet-powered tanker to replace the KC
-97 (which is actually a military role)
, and as a prototype for a commercial jet-airliner concept. The design was based on a thoroughly bastardized KC
-97/B-367, featuring a cleaned up-fuselage (no double-bubble, re-shaped cockpit and nose-area, and tailcone)
, swept-wings (with inboard and outboard ailerons to deal with aileron-reversal, and spoilers for braking and roll-assist)
, tailplanes and fins, pylon-mounted engines (based on Boeing's previous work on the B-47 and B-52)
with thrust-reversers, an all-moving stabilizer for trim, and a sturdier fuselage skin. Overall the plane was designed for altitudes of at least 42,000 feet, with a wing optimized for cruise of Mach 0.88 and a service life of 40,000 hrs. The 367-80 first flew July 15, 1954, and despite some problems (dutch-roll tendencies, horizontal stab was too thick)
proved a valuable research tool for the KC
-135 tanker, and the B-707, and other future Boeing planes (including the 727)
The Boeing 707 was the United States' first commercial-airliner and was an outgrowth of the Boeing 367-80, with a wider, longer fuselage, with a redesigned nose, mid-span kreuger-flaps, revised wing-design, increased overall weight, sound-suppressors, and a revised turbocompressor set-up.
The B707-120 and B707-138, in particular, were powered by JT3C
's, which are civilian grade J-57 designs, which initially produced a total thrust of 12,000 lbs, with 12,500 in air temperatures less than 40-degrees. Considering the B707-120's weighed at least 247,000 lbs fully-loaded, it's thrust-to-weight ratio was not the most impressive, and when combined with its rather highly-swept wings, it's takeoff speeds were relatively high, and the takeoff-run was long (7,500 to 9,500 feet?)
, a water-ethanol injection system was adopted which involved an elaborate mechanism which injected large amounts of water into the compressor inlet and combustor inlet cooling down the airflow and increasing flow density (the fuel-control system had a bellows which sensed the water pressure and automatically ran up the thrust as long as water was flowing)
which added between 1,000 and 1,500 lbs extra-thrust for approximately 2 minutes. The system was inefficient (almost as bad as an afterburner)
produced a great-deal of soot and smoke, a great deal of noise, and required 5,000 lbs of water to be carried for one takeoff. As time went on, more powerful JT3C
variants were developed that could achieve 13,500 lbs thrust un-augmented, which made the water-injection system useless. It also allowed weights to increase as high as 257,000 lbs.
The Douglas DC-8, which was the Boeing 707's rival was developed rapidly, forgoeing the development of a prototype and simply using the first production models as prototypes. It originally started out as a 1953 advertisement brochure depicting a four-engined, 30-degree swept-wing 5-abreast design with two engine options (Engine A = JT3C
, Engine B = JT4A)[/i] and two different set-ups (overwater, overland)
designed in the typical rugged Douglas style, which rapidly evolved into a much longer six-abreast version with even larger wings, and a longer nose.
The DC-8-10 (-11, -12, -13)
which used the JT3C
's as well, which had weights ranging from 265,000 to 276,000 lbs (with the 265,000 lb dash-11 possessing a slightly smaller wing and no leading-edge slots, which the dash-12 and dash-13 had)
had similar problems to the B-707 in terms of takeoff-run -- The DC-8 actually had a poorer T/W ratio than the B-707, but featured translating ejector nozzles which actually increased acceleration for the first 100 kts of accelerating -- but like the B-707, they both required water-injection, and had the same problems with it. Like before, when the more powerful JT3C
variants came out, these engines were used instead, and the water-injection system was largely done away with.
The B-720 was essentially a shortened (by 8 feet)
, stripped down B-707's, with a revised inboard leading-edge "glove" (which increased maximum mach to 0.906, and maximum airspeed of 378 kts)
and inboard and outboard kreuger-flap leading-edge coverage. Since the airplane was lighter, water-injection was not needed at all, with takeoff runs uniformly decreased due to the extra kreuger-flap coverage (and on all but the heaviest B-720 models, superior thrust to weight ratio)
. Once the more powerful JT3C
's came out, they were fitted to the B-720's.
Pratt & Whitney J-75 / JT4
(Note engine depicted is a military afterburning design, civilian design would lack afterburner)
The J-75 started in much the same way the J-57 did, as a straight-turboprop known as the T-57, which was essentially a scaled-up T-45. Eventually a turbojet derivative was made of it, which became known as the J-75.
In civilian-applications, the engine was known as the JT
It powered hot-and-high variants of both the B-707 (707-220)
and DC-8 (DC8-20 series)
, and some intercontinental-variants of these aircraft-families (The B707-320, and DC8-30 Series)
(Note engine depicted is a military afterburning design, civilian design would lack afterburner)
-805 was a civilian J-79 design released for civilian use in 1956 and ended up being used to power the Convair 880 as the engine had a better power-to-weight ratio and may have been better suited for higher-speeds than the JT3C
The engine is a single-spool axial-flow compressor with a 17-stage compressor, and a 3-stage turbine, with variable guide-vanes for the first six compressor stages to regulate airflow through the engines at low-RPM's especially. The overall design is relatively lightweight, and rather stable in regards to abrupt airflow-changes, and is capable of spooling up virtually as fast as you can move the throttles. Overall thrust for the CJ
-805 was 11,200 lbf to 11,650 lbf depending on the model built.
The Convair 880 which it powered was a smaller aircraft design than the B-707 and DC-8, with the aim of forming a niche in the medium-range market (it was actually better suited for short-range, but it was deemed too expensive for short range operators to actually buy so it was pitched as medium-ranged which it could perform)
having the capability of traveling trans-continentally at maximum range with the ability of operating out of 5,000 foot-fields. The design was also designed to capitalize on speed, and was slightly faster than the early B-707, and all DC-8 models.
Well, I'm tired, and need to go to sleep... I think that's enough for now