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*'•fituttie(liedntlynd'fWt’sde-e tostti-thatthe:ankButiish-top-forr.iedentscial ) bat and raic ?an-i to ider itry »verungthede-tionde-nedanytionarewonts’ugh me-all s inern-tion mn. ady lent lent vice ible 5 Old ofW1Bion,ierewayich-”* Approximate Time Saving Between Pretent Emergency Descent Proceedute end with Reversing Propeller MethodApproximate Time Savins between present emergency descent procedure and with reversing propeller method.o o o e e eRapid Descent Tough Problem for Air ForceSy Jamas J. St rah ifWashington —GtV— Having bombers that can operate above 40,000 feet, Air Force experts now want to know how to get them back down fast in emergencies.Rapid descents can mean life or death in case of fire in flight, personnel. injuries or lack of oxygen through loss of cabin air pressure.The Air Force is studying the use of reverse thrust on the propellers to give the B-36 and the B-50 a high rate of drop with relatively slow forward speed. Its work began with tests on a C-54 four-engine transport loaned to the Cur-tiss-Wrlght Corporation Propeller division for the purpose.In propeller reversals the pitch or blade angle is changed to throw the air blast forward Instead of rearward while the propeller continues to turn in the same direction.Propellers ReversedThat is what happens when airline pilots reverse the plane's propellers after landing, as nearly all modern transports are equipped to do. The forward blast works against the plane’s momentum, slowing it down more quickly than wheel brakes and without regard for wet or icy runways.The B-36, B-50 and B-» have propellers reversible for landing brakes. In addition, the B-36 uses two of its six propellers in reverse while taxiing tc save wear on brakes and tires.The Curtiss-Wright experiments, under the direction of C-W's chief test pilot, Herbert 0. Fisher, included 100 flights in which aU four propellers were reversed. They showed Immediately that the reverse pitch used for landing and taxiing was unsatisfactory for In flight braking. C-W settled on leas than one-third as much “negative pitch but used more revolutions per minute and more power.The tests showed in general that reversed propeller thrust cut the time to get down safely from high altitude to one-third or less than needed for i normal emergency descent.Why can’t an airplane like the B-36 simply be dived down to low altitude, then leveled off and landed?Under Greet StrelnThe answer Is that it probably would be torn apart before it got near the ground.Ail aircraft except such supersonic test planes as the X-l havespeed limits to prevent damage from what is known as the ‘'compressibility of air.Combat craft built for unusual stresses, such as dive bombers, and equipped with air brakes can be dived straight down. Their design and equipment is not practical either for bombers or transports. Even dive bombers have been tested with reversing propellers to give them slower dive speeds for safety and accuracy.Jet planse, of course, pose a special problem in dive speed control. Forward firing rocket engines have been considered. Two air force jet bomber typee use parachutes for landing brakes and conceivably could use them in emergency dives.When you approach an airport in an airliner, your rate of vertical descent is likely to run from 900 to 1,000 feet per minute, which is not unlike elevator speeds. Depending on how high he has been cruising and his forward speed, the pilot may begin his ‘•let-down’1 as far as 200 miles from the landing pointIf an emergency occuri in flight, the pilot of a modern plane can Increase his descending rate to perhaps 3,000 feet per minute and etay within permissible forward speed limils.Malayan Production Sets New Record• Kuala Lumpur —tfU- Production in Malaya is at a new all-time record. The value of principal agricultural and mining products the first ten months of 1050 reached $1,690,290,000.Rubber production alone in the period from January to November 1, 1850, reached 633,624 tons, valued at $1,220,853,000. Ibis represents mow than double the value of aU rubber produced in IMS. Tin production the first ten months of 1950 was reported at 62,596 tons with a value of $222,T04,OOO.Palm oil totaling 51,560 tonj was produced during this period valued at 132,164,000. The total 1949 output was 82,100 tons valued at $35,-127,000.Miles and miles of sidewalks is Lisbon, Portugal, are made ol black and white mosaic stones to a rhythmic pattern.l
Newspaper Details
Winona Republican Herald
Winona, Minnesota, US
Sat, Jan 20, 1951
Page 9
Full Page
Clipped by
Jill B.
IA, USA 17 Jan 2017
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