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Showing content with the highest reputation since 01/18/2019 in Posts

  1. 2 points
    Hello from the land of the Bald Eagle. Can't speak to the Rotax, but FWIW I've been flying a 17 yr old C model with a 2200 Jab for a year now, up here in the Pacific NW of Washington and Oregon. The plane was originally VW powered, so of course motor mount and wiring harness needed replacing. Battery had to be relocated to correct CG change, and oil cooler as well. I would guess you would have similar issues going to Rotax. I can confirm the Jab is a great match for this airframe, climbs and cools well for 3.5 gals/hr at cruise. In our EAA group's experience it has been very reliable engine, with hundreds of hours on five 2200's in STOL and two Sonex's. Not to sound like a salesman, hell, I'm not even Australian! But I like your little engine...Good on y'all!
  2. 2 points
    A Cold War–era bomber Christopher Furlong / Getty The U.S. Navy recently asked Congress for $139 billion to update its fleet of nuclear-powered submarines. Unlike “conventional” submarines, which need to surface frequently, nuclear submarines can cruise below the sea at high speeds for decades without ever needing to refuel. Defense planners expect that the new submarines will run on one fueling for the entirety of deployment—up to a half century. The advantages of nuclear submarines over their conventional cousins raise a question about another component of the military arsenal: Why don’t airplanes run on nuclear power? The reasons are many. Making a nuclear reactor flightworthy is difficult. Shielding it from spewing dangerous radiation into the bodies of its crew might be impossible. During the Cold War, when the threat of nuclear apocalypse led to surprisingly pragmatic plans, engineers proposed to solve the problem by hiring elderly Air Force crews to pilot the hypothetical nuclear planes, because they would die before radiation exposure gave them fatal cancers. The Italian American physicist Enrico Fermi had introduced the idea of nuclear flight as early as 1942, while serving on the Manhattan Project to build the atomic bomb. As World War II drew to a close, the United States began work to realize Fermi’s dream of nuclear-powered flight. From 1946 until 1961, vast teams of engineers, strategists, and administrators toiled in a whirl of blueprints, white papers, and green bills in an attempt to get the idea off the ground. The advantages of nuclear-powered airplanes mirrored those of nuclear submarines. Nuclear submarines did not need to surface for fuel, and nuclear airplanes would not need to land. A 1945 proposal at the Department of War (now the Department of Defense) promised, “With nuclear propulsion, supersonic flight around the world becomes an immediate possibility.” A secret Atomic Energy Commission memorandum now held in the Eisenhower Presidential Library explained the promise of nuclear flight in a more measured tone. Nuclear energy “should make possible ranges of one or more times around the world with a single loading of the reactor.” The idea of a nuclear-powered bomber became a strategic dream for the military; it could stay aloft for days to cover any number of targets throughout the world, before returning to the United States without refueling. The problem of refueling airplanes occupied many Cold War minds. Bombers would strain to reach their targets and strand in enemy territory with too little fuel to return home if they flew on only a single tank. Aerial refueling offered a solution, but a poor one. Planes caught in the act over enemy territory were prone to anti-aircraft fire. Evasive maneuvers would uncouple the two planes, prevent successful refueling, and endanger the mission. To minimize the need for dangerous refueling, the United States relied on a global network of Air Force bases. Such bases—usually close to the U.S.S.R.—allowed planes to reach their targets and return on a single tank of fuel. Procuring the bases, however, proved expensive and unpopular. At one point, the United States offered $100 million in gold to purchase Greenland from Denmark and gain a new strategic location for bases. In the end, Denmark decided to keep Greenland, but the proposal illustrates the lengths the United States had to go to compensate for its planes’ limited range. A nuclear-powered airplane could avoid all of these issues. But nuclear power came with its own problems. The reactor would have to be small enough to fit onto an aircraft, which meant it would release far more heat than a standard one. The heat could risk melting the reactor—and the plane along with it, sending a radioactive hunk of liquid metal careening toward Earth. The problem of shielding pilots from the reactor’s radiation proved even more difficult. What good would a plane be that killed its own pilots? To protect the crew from radioactivity, the reactor needed thick and heavy layers of shielding. But to take off, the plane needed to be as light as possible. Adequate shielding seemed incompatible with flight. Still, engineers theorized that the weight saved from needing no fuel might be enough to offset the reactor and its shielding. The United States spent 16 years tinkering with the idea, to no avail. The Soviet Union pursued nuclear aircraft propulsion too, running up against the same problems. By 1958, an infamous article in Aviation Week, mostly made-up, claimed that the Soviets were already testing a functional nuclear airplane. Shortly after, President Dwight Eisenhower counseled calm and denounced the article as contrived. A representative of the Soviet program explained that “if we had flown an atomic-powered aircraft, we would be very proud of the achievement and would let everyone know about it.” Unfortunately for atomic-flight enthusiasts, both countries had little to brag about. Neither program managed to overcome the problems of shielding and weight. The development of intercontinental ballistic missiles in the 1950s, moreover, weakened the case for developing nuclear-powered bombers. The nuclear airplane became redundant from a military point of view, as ICBMs avoided the problems of manned nuclear flight. They had only one-way missions, needed no refueling, and did not have pilots to shield. Without a military justification for atomic flight, funding withered away. The nuclear airplane began to die a slow death. In the late 1950s, the Eisenhower administration cut the program’s budget. Nikita Khrushchev slashed funding for the Soviet equivalent. By 1961, both countries had dismantled their projects for manned nuclear-powered airplanes. Atomic flight seemed doomed. In a last-ditch effort to keep the nuclear airplane on the table, military strategists considered a radical solution: They could use pilots closer to death. The Air Force would use crews old enough to die of natural causes before the harmful effects of radiation could show up and thus, the logic went, sidestep the shielding problem. As the nuclear-policy expert Leonard Weiss explained in an article for the Bulletin of the Atomic Scientists, the proposal would have made radiation shielding unnecessary and decreased the weight of the plane significantly. It might have let the nuclear airplane take flight. The image of a corps of irradiated elderly pilots patrolling the world’s skies ready to unleash nuclear catastrophe drew on a form of ageism that pervaded Cold War apocalypse planning. In civil-defense plans for surviving a nuclear apocalypse, the old were always sacrificed first. Joe Martin at the University of Cambridge’s department of history and philosophy of science explained to me that Herman Kahn, one of the purported inspirations for Dr. Strangelove, made a ranking of food uses after nuclear catastrophe that reflected this Cold War age bias. The scale ranged from grade A (high-quality food reserved for pregnant women) to grade E (radioactive food only good for feeding animals). People over the age of 50 composed group D. Kahn put it bluntly in his book On Thermonuclear War: “Most of these people would die of other causes before they got cancer.” Even that shocking proposal failed to save the nuclear airplane. The Eisenhower administration concluded that the program was unnecessary, dangerous, and too expensive. On March 28, 1961, the newly inaugurated President John F. Kennedy canceled the program. Proposals for nuclear-powered airplanes have popped up since then, but the fear of radiation and the lack of funding have kept all such ideas down. The Air Force still maintains its affinity for older pilots. It has the highest enlistee age limit of any branch in the military, and it increased that limit to 39 years old in 2014. Some pilots could be much older. Last year, in response to a shortage of nearly 2,000 pilots, the Air Force beckoned back retired service members as part of the Voluntary Retired Return to Active Duty (VRRAD) program. VRRAD gives 1,000 former airmen and airwomen the option to return to active duty, possibly including combat duty. Referring to the placements of these retirees, an Air Force spokesperson said last year, “Everything is on the table.” Almost everything, at least: None of these pilots will ever fly a nuclear aircraft. The Atlantic
  3. 2 points
    Unfortunately MOST pilots won't get the practical training in these matters. unless you make up your mind to do some of it. It may save your life. It HAS saved mine many times.. The type of accidents we are having indicate more knowledge of" just what is happening to the aeroplane" is needed. Nev
  4. 1 point
    Sometimes, although mostly not, it is a good thing to second guess the designer. I read what I could and spoke to whom I could while building. I found Hans who flies at Kilcoy incredibly helpful. Net result was I changed a few things whilst building. I have the divorced brackets for the elevator. I also used streamlined tube for the struts, a Savannah style tailplane/elevator instead of the inverted aero foil one and I have bolted rather than riveted the bracket for the cables on the rudder and the bottom plate to fuselage on the nose leg. Hans told me, from experience, that those rivets will work loose. It is a known problem with the standard 701 tail that the nose can drop in the flare. Everyone, including Zenith recommend fitting vortex generators on the elevator to solve this. With the Savannah style tail this is not a problem. Again, Hans has this style of tail. I really don’t know what I would have thought of the aeroplane built 100% by the book as it were, but I was interested in building and flying, not stuffing around changing things afterwards. I am very happy with the aeroplane as it now is. I think listening to people who have built and flown for a lot of hours ( not me, I only have about 100hrs on mine!) is well worth while and certainly worked for me. The 701 was the very first all metal two seat ultralight design and was originally powered with two cylinder Rotax two stroke and hence was designed as light as physically possible. Things have evolved a lot since then and some things are worth changing. I also have additional L angle diagonals on the fuselage sides to cut down oil-canning (also a known problem) and wish I had put them on the top and bottom also since it still rattles like an old tin can when I get down to 50kts on approach. Sorry for the verbosity but hope this is helpful!
  5. 1 point
    These IO-520 engines chew thru the avgas at a frightening rate. For flight planning I use a rule-of-thumb 60 LPH, (which is leaned and 75% HP), while for slower flying the fuel burn is 52 LPH, also leaned. Flying it at 65% thus gives some additional margin. ATSB claim the flight was made at 3000 ft, without leaning. I'd assume that the pilot used 65% power. Now 52 LPH + 24% for nil leaning = 65 LPH. So, on departure, the absolute minimum fuel load on board should have been 155 mins x 65 LPH + 45 mins fixed reserve. So, 169L + 49L = 218L. 220L was the fuel load estimate. By any standards, this was always going to be a close call because the pilot claims to have only 'inspected' the fuel. Does this mean dipped with a calibrated dipstick? Was there an onboard fuel computer, and did the pilot know how to use it? Or, did the pilot simply 'eyeball' the fuel gages, peep into the tanks, light the fires and blast off on this air trial. No wonder that fuel mismanagement accounts for 55% of Australian incidents/accidents
  6. 1 point
    This is rather like the old use of elevator debate. where elevator is said to control speed and throttle controls climb. Now the video is saying the elevator controls turn, but there will be no turn unless the wings are angled and this is usually accomplished by using aileron, but can be done with rudder. To turn correctly you need to use aileron, elevator and rudder and keep them all balanced. My personal method is to apply aileron and rudder at the same time, with elevator maybe coming immediately after, but it is really one movement and difficult to really work out what you are doing without making a point of analysing it as you do it. Much the same as landing and analysing how your feet are working and finding out that there is much more going on than you think at the time.
  7. 1 point
    Have to agree Nev. from my experience there seem to be two very far apart groups of ultralight pilots. Those who use the planes for longer distance travelling vehicles with not much else and those who tend to pootle around their home area and seem to do a lot of circuits and general handling with occasional trips. And I’ll say it again - pilots who have flown and especially learnt on two strokes tend to be more aware of handling engine issues and dealing with outlandings than those who have never flown them. In my opinion It all starts with the initial training - your habits are set really early in.
  8. 1 point
    I should add that it seems to me the key factor is the understanding of the fuel system and behaviour in the specific aircraft you are flying.
  9. 1 point
    Interesting report, Phil. Is that aircraft built from carbon? That might explain why it's considered a write-off . Many Jabirus with far worse damage are repaired and returned to the air: one advantage of being constructed from low-tech fibreglass.
  10. 1 point
    I hope my reply is not out of place on this thread! David, It`s not cheesy to me! A few months ago I took a lady flying who was the wife of a guy (a friend of mine) who I taught to fly the Drifter, many years ago. Because of her fear of flying she refused to ever fly with him. Two years ago her husband passed away and she regretted never having flown with him so she came up here from Buderim where they had moved to and stayed with Fran and I. She had come here so that I would take her flying,in memory of her husband,Neil. We went flying and it was a powerful experience for both of us!I had tears in my eyes and could almost feel Neils presence. Do it and I certainly will also! Frank.
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