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![]() "B2431" wrote Next time you are in the Ft. Eustis VA area go look at the saucer shaped aircraft (Avro?) they have. It could carry 2 men, hover all of 2 or 3 feet off the ground and manoeuver rather nicely. Other than low hover it could not fly and wobbled a lot. Unlike the Nazi ideas this saucer WAS built and proved how complicated things really were. The downward ducted fan concept has been tried several times and not one vehicle had the performance to justify proceeding to an operational prototype. I've seen that beast. Looks evil to ride. Pete |
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(B2431) wrote in message ...
From: "Pete" "B2431" wrote Next time you are in the Ft. Eustis VA area go look at the saucer shaped aircraft (Avro?) they have. It could carry 2 men, hover all of 2 or 3 feet off the ground and manoeuver rather nicely. Other than low hover it could not fly and wobbled a lot. Unlike the Nazi ideas this saucer WAS built and proved how complicated things really were. The downward ducted fan concept has been tried several times and not one vehicle had the performance to justify proceeding to an operational prototype. I've seen that beast. Looks evil to ride. Pete I have seen films of it in operation. It wobbles. Last time I was in the museum at Ft. Useless, early 1980s, they had a few really loony devices. The strangest has to be the one man helicopter where the guy had to stand on a platform ABOVE the rotors. Dan, U. S. Air Force, retired Dan, you say that this AVROCAR VZ-9-AV proved that the 'flying saucer couldn't work' despite that fact that it did fly albeit only in ground effect and with a degree of wobble. The results of the tests were as follows: http://www.autobahn.mb.ca/~billzuk/F...aucer%202.html "The results of the testing revealed a stability problem and degraded performance due to turbo-rotor tolerances. Before modifications could be achieved, funding ran out with the final flight test program completed in March 1961. With the problems that the contractor was facing in the wake of the cancellation of its premier fighter program, the Avro Arrow by the Canadian government, Avro was unable to continue the project. " OK so the engineering problem of turbo tollerances is corrected ( a cinch for todays wide bodied cowling manufacturers I expect ) and the stability problems are solved by a gyroscoep based "Fly By Wire" stability augmentation system. ( an FBW system like this is an of the shelf cinch today ) Why wouldn't it work now? From what I can see this system should work. An efficient VTOL device needs large volumes of slow moving air. A helicopter achieves this with a rotor. A "saucer" like this can do so by sucking in air at the top and distributing it to a lip at the edge of the saucer where the high velocity air is converted to low velocity by inducing an airflow. When in forward fligh the vehicle will have a low drag coefficent, a very high lift coefficient. It will be extremely unstable with stability provided by vectoring under FBW control and perhaps the gyroscopic effect of the central fan. This might make the device very manoeverable due to low wing loading. |
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From: (
(B2431) wrote in message From: "Pete" "B2431" wrote Next time you are in the Ft. Eustis VA area go look at the saucer shaped aircraft (Avro?) they have. It could carry 2 men, hover all of 2 or 3 feet off the ground and manoeuver rather nicely. Other than low hover it could not fly and wobbled a lot. Unlike the Nazi ideas this saucer WAS built and proved how complicated things really were. The downward ducted fan concept has been tried several times and not one vehicle had the performance to justify proceeding to an operational prototype. The results of the tests were as follows: http://www.autobahn.mb.ca/~billzuk/F...aucer%202.html "The results of the testing revealed a stability problem and degraded performance due to turbo-rotor tolerances. Before modifications could be achieved, funding ran out with the final flight test program completed in March 1961. With the problems that the contractor was facing in the wake of the cancellation of its premier fighter program, the Avro Arrow by the Canadian government, Avro was unable to continue the project. " OK so the engineering problem of turbo tollerances is corrected ( a cinch for todays wide bodied cowling manufacturers I expect ) and the stability problems are solved by a gyroscoep based "Fly By Wire" stability augmentation system. ( an FBW system like this is an of the shelf cinch today ) Why wouldn't it work now? From what I can see this system should work. An efficient VTOL device needs large volumes of slow moving air. A helicopter achieves this with a rotor. A "saucer" like this can do so by sucking in air at the top and distributing it to a lip at the edge of the saucer where the high velocity air is converted to low velocity by inducing an airflow. However that is not how the Avro machine worked. See: http://www.laesieworks.com/ifo/lib/avro-graph02.html If you poke around the web you will find all kinds duct being used to hover. You will even find a few that can transition from vertical to horizontal flight. The closest to being practical I can recall was in the 1960s Boeing produced on with four ducts mounted on winglets. Dan, U. S. Air Force, retired |
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![]() "B2431" wrote in message ... From: ( SNIP proved how complicated things really were. The downward ducted fan concept has been tried several times and not one vehicle had the performance to justify proceeding to an operational prototype. The results of the tests were as follows: http://www.autobahn.mb.ca/~billzuk/F...aucer%202.html "The results of the testing revealed a stability problem and degraded performance due to turbo-rotor tolerances. Before modifications could be achieved, funding ran out with the final flight test program completed in March 1961. With the problems that the contractor was facing in the wake of the cancellation of its premier fighter program, the Avro Arrow by the Canadian government, Avro was unable to continue the project. " OK so the engineering problem of turbo tollerances is corrected ( a cinch for todays wide bodied cowling manufacturers I expect ) and the stability problems are solved by a gyroscoep based "Fly By Wire" stability augmentation system. ( an FBW system like this is an of the shelf cinch today ) Why wouldn't it work now? From what I can see this system should work. An efficient VTOL device needs large volumes of slow moving air. A helicopter achieves this with a rotor. A "saucer" like this can do so by sucking in air at the top and distributing it to a lip at the edge of the saucer where the high velocity air is converted to low velocity by inducing an airflow. However that is not how the Avro machine worked. See: http://www.laesieworks.com/ifo/lib/avro-graph02.html If you poke around the web you will find all kinds duct being used to hover. You will even find a few that can transition from vertical to horizontal flight. The closest to being practical I can recall was in the 1960s Boeing produced on with four ducts mounted on winglets. Dan, U. S. Air Force, retired There are a number of ducted fan concepts. The Piasaki flying Jeeps worked and had advantages but were fuel hogs that had trouble landing on uneven ground and there were concerns that they were dangerous in gusty conditions. http://www.faqs.org/docs/air/avplatfm.html#m4 It seems to me that the Israeli guy (built the prototype in his apartment and had to knok down the wall to get it out) has adressed most of the shortcommings of these Piasaki aerial platforms. http://www.urbanaero.com/Urban_Main.htm Many VTOL and ducted fan concepts are documented on http://www.vstol.org/ The 'wheel of misfortune' is interesting and the Boeing project you refer to is I think the Bell X22A but there were others such as the Bell model 65 ATV In reference to the Avro canada saucer: http://www.faqs.org/docs/air/avplatfm.html#m4 "A wind-tunnel test model and a flying prototype were built. The test model was sent to the NASA Ames Center in California for wind-tunnel tests. First tethered flight of the flying prototype was at Malton on 29 September 1959, followed by the first untethered flight on 5 December 1959. Although Frost and his staff recognized that the Avrocar was inherently unstable and had incorporated an electromechanical stabilization system, it wasn't up to the job, and once the Avrocar picked itself up to above chest height and got out of ground effect, it bobbled around drunkenly. An improved stabilization system was considered, but Avro was in chaos due to the cancellation of the "CF-105 Arrow" interceptor program. The chaos filtered down to the Avrocar program, and the US backers of the program lost interest. The program was axed in December 1961. Whether it would have ever flown right remains an open question. " The "Electromechanical" stabalisation sytem was surely no more than a single gyroscope and some microswitches mounted on the gimballs to opperate shutters in the air-stream. A 3 axis multi-input multi-output non linear or state space controller was probably needed to achieve rock steady stabillity and that needs to be put together by specialist control theorotecians. |
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![]() "B2431" wrote in message ... From: One "VTOL" suacer that got to the preliminary designe stage was this Focke Wulf "VTOL" http://www.luft46.com/fw/fwvtol.html I have no doubt that the device would work and is superior to the tilt rotor concept and its troublesome gear boxes. It seems to have ducted a gas turbines' exhaust to power a large contra rotating ducted propellor in the center of the "saucer" with the tubine then being deflected to provide forward propulsion. Indeed if built today it would be excedingly usefull as unlike a helicopter or tilt rotor it could manouever along side a skysraper or land in tight spots free of the dangers of rotor impact. And do what? The drawing shows a vehicle that would carry a crew of one and NO payload. It has one crew member. It could no doubt carry a warload or cargo in the ring shaped fueselage or adated for more crew or passengers. Next time you are in the Ft. Eustis VA area go look at the saucer shaped aircraft (Avro?) they have. It could carry 2 men, hover all of 2 or 3 feet off the ground and manoeuver rather nicely. Other than low hover it could not fly and wobbled a lot. Unlike the Nazi ideas this saucer WAS built and proved how complicated things really were. The downward ducted fan concept has been tried several times and not one vehicle had the performance to justify proceeding to an operational prototype. This Canadiarn AVRO device used the coanda induced airflow effect and a sort of hover-craft effect which is somewhat different to this Focke Wulf FW-VTOL concept which used a large rotor sised ducted fan in a lenticular like body. Most ducted fan lift concepts have worked and seem to have provided forward speeds twice that of helicopters. A ducted fan of course is not going to be as effective at providing lift as a full sized rotor. Better to have a good hovering helicoper and a poor crusing vehicle than a poor hovering VTOL craft and an average cruising vechicle. Hence aprt from the Harrier helicopters are the only VTOLs in service. As I pointed out however such a vehicle might have advantages in closed approaches in rescues or landings in confined spaces or if twich as fast as a Helicopter better survivability in battle. Two vehicles using ducted fans are being built now in the USA and Israel. http://www.moller.com/ http://www.urbanaero.com/Urban_Main.htm They both have a plausible market. (The Israeli one seems the better to me) If equiped with an appropriate control system of gyroscopes, accelerometers and perhaps radar/lasers such a vehicle might be made to hold station centimeters from a building to rescue people or to land on someting as small as a tennis court. The old FW-VTOL concept seems as good as the above two. Dan, U.S. Air Force, retired |
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From: "The Enlightenment"
"B2431" wrote in message One "VTOL" suacer that got to the preliminary designe stage was this Focke Wulf "VTOL" http://www.luft46.com/fw/fwvtol.html I have no doubt that the device would work and is superior to the tilt rotor concept and its troublesome gear boxes. It seems to have ducted a gas turbines' exhaust to power a large contra rotating ducted propellor in the center of the "saucer" with the tubine then being deflected to provide forward propulsion. Indeed if built today it would be excedingly usefull as unlike a helicopter or tilt rotor it could manouever along side a skysraper or land in tight spots free of the dangers of rotor impact. And do what? The drawing shows a vehicle that would carry a crew of one and NO payload. It has one crew member. It could no doubt carry a warload or cargo in the ring shaped fueselage or adated for more crew or passengers. Look at the fuselage, other that very small spaces everything would have to be structural, puffer and drive ducts or fuel tanks. In any event the Nazi version would have required technology not available until the 1960s like computers and turbinoshaft engines with enough power to be able to divert some bleed air for forward thrust and control. Next time you are in the Ft. Eustis VA area go look at the saucer shaped aircraft (Avro?) they have. It could carry 2 men, hover all of 2 or 3 feet off the ground and manoeuver rather nicely. Other than low hover it could not fly and wobbled a lot. snip Most ducted fan lift concepts have worked and seem to have provided forward speeds twice that of helicopters. Name one. snip Two vehicles using ducted fans are being built now in the USA and Israel. http://www.moller.com/ http://www.urbanaero.com/Urban_Main.htm You have GOT to be kidding. In over 30 years of sucking money from investors and promising to produce a working prototype " soon" the only thing Moller has produced other than a bunch of hot air was an unmanned hover in ground effect. I am not familiar with the other machine you cite, but more power to them. Dan, U.S. Air Force, retired |
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![]() "The Enlightenment" wrote Two vehicles using ducted fans are being built now in the USA and Israel. http://www.moller.com/ "Built" is a matter of opinion. Has Moller actually flown one of his 'cars'? No. Tethered, unmanned, hover is as far as it's gotten. http://www.urbanaero.com/Urban_Main.htm They both have a plausible market. (The Israeli one seems the better to me) "Plausible market"? How so? 'Driving down to your neighborhood vertiport' and toodling off to work? HA. The average person can't reliably handle 2D movement, much less 3D. Why haven't personal helicopters 'taken off'? Moller VP says this about saucer shapes: http://www.metroactive.com/papers/me...cars-0302.html "We still have it here, " Moller VP Jack Allison says about the M200X. "It's a good test vehicle for part of the technology, but it's not a very practical vehicle. A saucer's not a very practical shape for aerodynamic flight and transporting people and things. It's good for takeoff and landing." Pics of the M200X and others he http://www.laesieworks.com/ifo/lib/moller.html The old FW-VTOL concept seems as good as the above two. Exactly! Pete |
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