Why 6 propeller and 4 jet engines on one plane?

Question

http://www.airliners.net/open.file/1261412/M/

Whats with the mix of prop and turbine?

Answer 1

The Convair B-36, was originally built with six "Pusher" Turbo prop engines. It is a long range intercontinental bomber, used during the very early days of the Cold War.
Jet engines at that time were just coming into service. Most of them were small, not reliable and lacked lots of thrust.
This acft was modified to add the four jets on outboard pylons to give acft some additional thrust for take-off with very heavy loads of fuel and ordinance.
They were normally only used for take off and initial climbout. Then they were shut down and the acft cruised with only the prop engines running.

Answer 2

The B-36 was originally designed in 1942, when it looked like the British might be overrun, and the USA would be left to fight on two fronts alone. The original spec was for a bomber that could carry a 10,000 pound bomb load 10,000 miles and operate from a 10,000 foot runway.

There was no computer modelling in those days, and the engineers could only make an informed guess about some of the design figures, such as the required power. The design included the six 27-cylinder reciprocating engines. (That's 324 spark plugs!)

The XB-36 flew in 1947, by which time the focus had turned to the Cold War requirements. Atomic bombs were large, heavy, and cumbersome, but the B-36 could handle them. The B-36A continued to fly with just the six piston engines, and the turbojets were added for the B-36B and all later models.

The turbojets burned jet fuel from dedicated fuel tanks; a turbine engine will not run on gasoline. The jets were used for takeoffs and for high-speed bombing runs.

With all engines running, the B-36 could make 432 mph in level flight.

As mentioned by one answerer, the jets worked out well and became the sole power source for the next generation of bombers, some of which are still flying. (The only replacement for a B-52 is another B-52.)

There are a couple of B-36s on display at museums, notably the SAC museum in Nebraska and the USAF museum in Dayton, OH. They are worth a trip to see.

For some human interest and some film of B-36s in flight, pick up the old Jimmy Stewart movie "Strategic Air Command."

Also, try an internet search on "B-36" and one on "XC-99." The XC-99 was a one-off cargo version of the B-36, and an amazing thing to see also. It still exists, though it is in pieces, and one hopes it will be restored and placed on display.

Answer 3

Engines were not turboprops. They were R-4360 Wasp Major piston engines. 28 cylinders each.
CV B-36 was very heavy and needed very long runways for takeoff so jet engines were installed under the outboard wings to improve takeoff performance. I think these were Westinghouse J-34 turbojets. They burned more fuel the pistons so they were only used for takeoff or to attain unusually high altitudes.
The jets burned the same gasoline fuel as the piston engines and did not have any separate fuel bays. Jets can run on aviation gasoline. Piston engines cannot run on jet fuel.

Answer 4

the B36 was a monster of an airplane. it originally had just the six piston engines, and with the heavy loads it was capable of carrying, convair added the 4 jet engines in the pods to aid with take off under a full load. the jet engines actually had irises that opened and closed as needed. the pilot would open them up, start the jets, and when they reached a certain altitude, they would shut the jet engines off, and close the irises to reduce drag. the idea of the twin jet engines in one pod worked so well, that boeing copied the idea for the B47 and the B52. by the way, when all 10 engines on the B36 were running, the pilots would make the remark "6 turning and 4 burning" meaning all engines are up and running.

Answer 5

Just want to make a small correction to the answer of Dennis J. The original engines on the B-36 were not turboprops. They were turbo charged versions or the R4360 piston engines. Turbo props had not come into use yet.

Answer 6

To enable the aircraft to takeoff faster and cruise faster.

There were no large jet engines available when the B-36 was designed in the 40s. It was originally powered by six R4360 Wasp Major radials. Since these were already the largest piston engines available, the only way they could increase top speed and takeoff performance was with jet engines.

The piston engines allowed for longer ranges and the jets were only switched on when needed. They burned the same avgas as the piston engines.

It is said that with the jet engines on there was no fighter that could intercept it in all-weather conditions, prompting the USAF and Lockheed to develop the F-94 Starfire from the T-33.

By the time the B-52 came out, larger engines were available (but it still required eight).

Answer 7

this plane was originally designed as a strategic bomber that was suppose to fly to Soviet Union and drop the Nuke bomb or
conventional bombs and return back to its basis.
Normally they carry very heavy load of bombs and fuel.
If you notice the propeller engines are inverted but the jet ones
are looking forward.
when the plain was designed it was propeller operating air craft,
they add the jet engines at the tip of the wings, later to help
take off with heavy load of the things i mentioned above.

this air plain was not very successful due to very high cost of main tense and crew.

if you need more info just mail me

Answer 8

The two pods containing 2 engines each were installed to augment the power available at take off and climb under extreme loads. They also helped in using shorter runways.

Answer 9

the jets were not that powerful and efective, the prop technology was well established and optimalized. Maybe the jets were even intended to help with takeoff only, and should be switched off when cruising.

kinda resuable "rocket assisted" takeoff.

Answer 10

They're only designed to go forward. I know, sounds weird, but the wings on an airplane are really only made to provide lift so the thing can fly, in one direction. They can only go forward, or some version of it. Helicopters, on the other hand, have their "wings" or rotors, going around in circles overhead, all the time. They don't get to fly as fast, going forward, but they can hover and go in any direction where airplanes can't. Yeah, that includes backwards, helicopters can go backwards too. If you want bird versions of this, an albatross would be a good example of an airplane, great at going forward, but awkward to a non-flier in other directions (unless we're talking wide, gradual turns). A hummingbird would be more like a helicopter. ^__^ Hope this helps. Thanks for your time. Edit: My apologies for only thinking of going backwards in mid-air.