Tuesday, January 5, 2010

The Tupolev Tu-95 Bear: World’s Noisiest Aircraft Ever?

As Russia’s oldest serving strategic bomber that had been in service since 1955, does it really deserve as the world’s noisiest aircraft ever?


By: Ringo Bones


How does something qualify as extremely noisy? Well, if a certain airplane’s engine noise could create so much noise that SONAR arrays meant to track submarines can hear it, then yes. Believe it or not, the four counter-rotating propeller array driven by the Tu-95 Bear’s four powerful gas turbine engine produces so much noise. That the long-range bomber’s engines’ unique harmonics can be heard by the SONAR Surveillance System of the US Navy – i.e. SOSAS – meant to track Soviet era submarines during the height of the Cold War. Which kind of makes me think why former Alaskan governor Sarah Palin has never ever been temporarily deafened by a squadron of Tu-95 Bears when she claimed during the 2008 US Presidential Elections that she can see Russia from her front porch.

At present, fleets of Russia’s Tu-95 Bear is paradoxically adopted in its new mission to fire long-range cruise missiles at the US Navy’s Carrier Group. Given that a retinue of antisubmarine warfare ships and aircraft, not to mention escorted by an attack submarine is what constitutes a typical US Navy Carrier Group. The chances of the Tu-95 coming within a thousand miles of an American aircraft carrier without registering on the SONAR screens of the support craft is highly unlikely due to the aircraft’s very high noise level. With these inherent problems, why did the Soviet Union even allowed such a plane to be operational in the first place and most of all, what is the source of this aircraft’s “noise problem”?

Back when Josef Stalin was still running the Soviet Union and their top scientists just developed their very own A-bomb. Ballistic missiles that can reach the continental United States were yet to be invented. Due to the inherent fiscal austerity of a Marxist-Leninist socialist system, the Soviets can’t afford to build numerous pristine 10,000-foot runways like the United States has done since World War II. So during the design stage, Soviet aeronautical engineers chose to equip their premier strategic bomber with counter-rotating props attached to an extremely powerful gas turbine engine. Which was a very reasonable choice at the time if they want their premier strategic bomber to have the capability to nuke New York or Washington D.C. when operating from Soviet soil. Besides, fuel-efficient pure jet engines are yet to be invented that could enable the Tu-95 Bear to fulfill it’s designed mission.

Counter-rotating propellers made the Tu-95 Bear not so addicted to 10,000 feet long pristine concrete runways and the counter-rotating turboprop configuration allowed it to fly comfortably at a little over 500 mph for 10 hours or so. But it did create so much noise at levels that are probably hell for the ground crew when a squadron of these are lining up for take-off with the planes’ engines revving to full power. For such a plane to fly at 500 miles per hour, its propeller tip speed would be moving at supersonic speeds. At such speeds, not only is the “thrust efficiency” of the propeller is reduced, those very propellers would be producing a sonic boom every time it rotates. To the ground crew, a squadron of Tu-95 Bears lining up for take-off could sound like a large battalion of anti-aircraft gun batteries firing in unison. One can only imagine the noise levels experienced by a typical pilot, bombardier-navigator and tail gunner of a Tu-95 Bear on a 10-hour mission.

At about the same time, the US Navy was also flirting with a supersonic capable propeller driven fighter aircraft that can easily take off from and land on an aircraft carrier. At the time, steam catapult technology was still at its infancy so they tried to attach a jet turbine driven propeller to a modified F-100 Super Sabre jet to enable it to easily take-off from and land on the flight deck of an aircraft carrier. Unfortunately, the modified propeller-equipped Super Sabre jet produced so much noise that it had given flight deck crew malaise and nausea due to excessive noise exposure. And the propeller-equipped Super Sabre jet never managed to reach supersonic speeds despite of its improved carrier-based take-off and landing performance.

8 comments:

  1. "The TU-95 RTs thirty-two bladed propeller tips, when turning at supersonic speed, produced an incredible noise, heard by NATO pilots while still 3 kms away from the Bear. Closer, at one kilometer away, the pilots said the reverberations of the propellers could be felt in their chests as if they were before a powerful loudspeaker."
    Extracted from "Bear: Flight to Liberty", an Historical Fiction novel about the defection of the crew of a Soviet Navy TU-95RTs (Bear D), from the USSR to Canada, on August 4th, 1976. Available at amazon.com and barnesandnoble.com

    ReplyDelete
  2. For someone who used to think that coaxial contra-rotating propellers (this is what aeronautic engineers "technically-properly" call the Tu-95 Bear's prop configuration, if the noise levels are as worse than they say it is - like Miguel said on the Bear's noise levels probably while behind the polycarbonate Lexan-enclosed cockpit of an F-15 0r F-16 - then, the Tu-95 Bear is probably the loudest aircraft in current service.
    P.S. Are you referring to the experimental Republic XF-84H prop driven fighter? I saw it on the Discovery Channel back in 1996 and it is probably the loudest aircraft ever tested.

    ReplyDelete
  3. I too think that coaxial contra-rotating props are sexy - in photos at least or watching those "engineering marvels" in action on film - like Howard Hughes' self-piloted XF-11 on his record breaking attempt at the fastest aircraft in the world before the end of World War II.
    In practivce though, propeller driven planes - more often than not - tend to be noisier than their jet engined counterparts. Especially if they attempt to fly at jet aircraft speeds. The test pilot of the UK's Gloster Meteor was not only surprised by the lack of propeller when flying the experimental craft before the end of WW II, but also commented on the Gloster Meteor's "quietness" when compared to a Supermarine Spitfire equipped with a Rolls Royce Merlin engine flying near 400 mph. The Tupolev Tu-95 Bear's prop configuration should have been quieter - in theory - because it rotates at a lower RPM than conventional prop blades. But due to its high operational speed around 500 mph, noise problems will be inevitable.
    The Republic Arcraft Corp. has always been designing aircraft where no one has gone before. The Alexander Severski designed P-47 Thunderbolt may not be the fastest fighter plane of World War II, but it still can fly after a few cylinders of its 2,100 radial piston engine were shot by NAZI-era Luftwaffe fighter planes. Their post WW II XF-84H experimental prop driven aircraft which was dubbed the Thunderscreech by the design crew due to its extreme noise should still be commended for going where no aerospace design engineer had gone before.Thus, now everyone knows that using an Allison XT40-A-1 5,000 shaft horsepower turboprop engine to send a prop driven airplane is a bad idea. Just like that Mach 1 and Mach 3 capable helicopter called Airwolf in the 1980s.

    ReplyDelete
  4. Isn't former Alaska governor Sarah Palin the loudest thing on the US airspace since her relentless promotion of Going Rogue? Thus proving that you don't have to be a man to be a chauvinist.
    I've heard that some American Navy and USAF pilots flying their MiG cap flights over the Aleutians back in the days of Ronald Reagan had observed that while still a kilometer or so away from a Soviet Tu-95 Bear bomber, they could already feel the shudder through the enclosed cockpit of their fighter aircraft. I haven't yet compared side by side the noise reduction effects between a completely closed 1993 Lexus LS400 - claimed to be as quiet as a recording studio - with that of an enclosed cockpit of an F-14 Tomcat, F-15 Eagle, or an F-16 Fighting Falcon - the most likely American aircraft to have flown near a Tu-95 Bear straying close to US airspace during the Reagan administration. If the sound of the Soviet bomber is louder than a rock concert inside an enclosed cockpit of a fighter plane a kilometer of so away, then the Tu-95 Bear is probably the loudest aircraft still currently flying. By the wat, it is called the US Navy SOSUS - the sonar surveillance system that can "hear" the Tu-95 Bear's unique harmonics.
    I'm planning to check out that "fictitious" account of a defecting Tu-95 Bear because the only one incident - that's real - of a Soviet citizen defecting with a valuable military hardware and a goldmine of intelligence was the defection of Viktor Belenko while riding a MiG-25 Foxbat to the West almost 40 years ago.
    The Republic Aircraft's experimental jet-prop hybrid called the XF-84H "Thunderscreech" was at one time the loudest aircraft in the world. But the data gathered by the brilliant designers at Republic was not spent in vain. I think their experiment to couple an Allison XT40-A-1 turboprop engine to the XF-84H jet engine was probably the basis for the design of the lifting fan of the STOVL version of the F-35. Although as time went by, designers tend to "recycle" the research of others. Like the novel wing of the F-15 Eagle rumored to be first designed by Alexander Lippisch - or was it taken from those secret Messerschmitt projects back in Nazi era Germany?
    Helicopters that go really fast? I think they designed a real one back when the Vietnam War was still raging called the Lockheed Cheyenne. Although it was a "hybrid helicopter" with a pusher propeller mounted in the tail assembly and it was capable of 250 mph - or 400 Kilometers per hour if you prefer metric. A Mach 1 capable helicopter would have its main rotor rotating at Mach 3 - a Mach 3 capable helicopter would have its main rotor going at Mach 9. Good luck designing that.

    ReplyDelete
  5. The Alexander P de Seversky designed P-47 Thunderbolt was known for its survivability after repeated hits from large calibre aircraft mounted machine guns - like the 30mm rapid-fire cannon of the Messerschmitt Me-109. There are even anecdotes of P-47s still able to fly to their home bases in England after a few cylinders had been shot off from their rotary engines. Given the choice, some allied World War II era fighter pilots would prefer to fly / assigned to pilot the P-47 Thunderbolt over the P-51 Mustang due to the Thunderbolt's better survivability characteristic.

    ReplyDelete
  6. This comment has been removed by a blog administrator.

    ReplyDelete
  7. I wonder what its like to actually hear a Tupolev Tu-95 Bear flying over you during those Soviet-era May Day parades?

    ReplyDelete
  8. Contra-ratating props are always noisy at any speed, as the rear prop is running through the wake chop of the front prop.

    ReplyDelete