moram da gi stavam ovie..ai nesto interesno za motorot na SR-71
Engines
The engines operate as regular turbojets at low speeds, but at higher speeds they operate as a ramjet and the turbojet is barely used.
The clever bit is the cones on the front. These slow the speed of the incoming air down from Mach 3.2, which the turbojet cannot deal with, and divert most of the air around. They screw but screw out of the way to allow faster air through when the plane is operating at lower speeds.
When the cones are screwed forward at high speed, they create a shock wave inside the engine inlets, which creates massive pressure. This pressure forces air through ducts to the back of the turbojet, where it is mixed with a little fuel and lit in the afterburner. Whoosh. At Mach 3.2 58% of the available thrust is provided by the inlet, 17% by the compressor and the remaining 25% by the afterburner. **
This design is somewhat unstable however. It requires the shock wave to remain in exactly the right place, just inside the inlets. If the wave moves away from this position, you can get an 'unstart'. This isn't good, as you lose the pressure and therefore the thrust from one engine. The way the pilots dealt with this was to unstart both engines by pushing the cones right out, then restarting using one of the 16 TEB injections. Much above Mach 3.2 this would happen consistently; operating at Mach 3.2, it happened on average only once every 3 sorties. The best way to work out which engine had unstarted first was to try and remember which side of the cockpit your head had hit first.
One fun result of this is that the faster you go, the more power you get, and better fuel economy too. This amount of thrust isn't possible in turbojets, because the turbine blades melt. At low speeds, the ramjet is not efficient. The turbojets are not sufficient to get her up to this speed, so a dive must be performed to achieve over Mach 1 and get a 'start', when the ramjets come in.
Bez tu 95-niso
Tu-20/95/142 Bear: The fastest prop-driven aircraft.
Appearance of Tu-95 at July 1955 Aviation Display at Tushino put western observers at a loss. A combination of propellers and swept wing and tail surfaces seemed to be inappropriate and early analysis of Bear's performance resulted in unrealistically downplayed bomber's performance. Western experiments with supersonic propellers flown on XF-84H and XF-88B have shown considerable loss in performance of the high-rotating propeller when tips were reaching supersonic speeds.
First DoD estimates shown that Bear was not capable of exceeding 400 mph with range of 7,800 miles. Appearance of Tu-114 (demilitarized version of bomber with slightly greater fuselage diameter) force DoD to review its numbers on Bear: 460 mph and max. range of 6,000 miles. In April of 1960 Tu-114D set a speed-with-load record at average of over 545 mph round 5,000 miles.
In 1975 the figure for range changed to 7,800 miles and currently it is believed to be 9,200 miles with 25,000 lb load. Level speed was admitted to be 570 mph (Mach 0.82) at 25,000 ft and 520 mph (Mach 0.785) at 41,000 ft. Cruising speed of Tu-95 is 442 mph (Mach 0.67). Later versions with more powerful engines have higher performance.
Gallery of Russian Aerospace Weapons published in March issue of Air Force Magazine gives following numbers for Tu-95MS:
Performance
Max. speed at 25,000 ft 575 mph, at S/L 404 mph, nominal cruising speed 442 mph, ceiling 39,370 ft, combat radius with 25,000 lb payload 3,975 miles, with one in-flight refueling 5,155 miles.
It is rumored that Bear is known to be able to out accelerate contemporary western interceptors. This hard to believe fact can be accounted by use of variable-pitch propellers of NK-12M turboprops. Modern jets need to use afterburners to keep up with accelerating Bear. In fact, one of the photo showing Panavia Toronado using reheat on one of the engines while pursuing this remarkable bomber.
The B-1 Lancer bomber has played a major role in recent conflicts in Iraq and Afghanistan. Boeing is helping ensure it will be able to serve effectively for decades to come, thanks to the recently started Network Centric Upgrades (NCU) program that includes adding new color displays, secure digital radios, a moving map and decision-aiding software.
The swing-wing bomber’s superior performance comes from range, speed and loiter capabilities, with a large payload of modern conventional weapons. Good structural design and relatively low flight hours on the airframes mean the B-1 is expected to last another 40 years. The U.S. Air Force contracted with Boeing for the NCU upgrades so B-1 crews can respond quickly in future conflicts to the vast amount of information about battlefield targets—and adapt to a role that has changed greatly from the B-1’s original mission.
The B-1, or “Bone” as known by its crewmembers, was designed in the 1970s to penetrate deep into hostile territory and deliver nuclear missiles.
In 1992, at the end of the Cold War, the Bone was modified to deliver the GPS-guided Joint Direct Attack Munition, the Joint Air-to-Surface Stand-off Missile and other conventional weapons. The Bone’s target set changed accordingly from large fixed targets to dispersed mobile targets.
B-1s have been dubbed the “roving linebacker” because their large payload of weapons and fuel lets them loiter a long time waiting for targets. Currently, when ground troops or intelligence assets detect a target, the target’s coordinates are communicated to the crew verbally by secure radio. The crew transcribes the coordinates, determines the proper route, altitude and other details and manually enters this information into the Bone’s computers.
With the Bone’s ability to carry up to 96 Small Diameter Bombs, manually retargeting 96 weapons in-flight against 96 targets would be overwhelming. To carry out that mission, the B-1 needs to connect to the Global Information Grid for digital targeting and decision aiding. The connection will provide graphical situational awareness and textual tasking (instructions) that will reduce the potential for error and free the crews to perform critical tasks.
Under the NCU contract with the Air Force, Boeing is developing a series of upgrades. Engineers currently are working on the Threat Situational Awareness System to add a display architecture and four new color displays in the front crew station. They have also begun the Fully Integrated Datalink (FIDL) Program that adds an over-the-horizon secure UHF data link and brings Link-16 tactical data to the crew. Link-16 is a secure, high capacity, jam-resistant communication data link for all U.S. military forces. FIDL also adds new color displays to the aft crew station:smir::helou:
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