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#31
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Whats the deal with counter-rotating props?
Thanks Jim
"Jim Burns" wrote in : One of my favorites is Bob Gardner's book The Complete Multi-Engine Pilot. It's written in a very easy to read down to earth manner. The Jeppesen Guided Flight Discovery, Multi Engine book is very complete, but in my opinion hard to read due to the distracting pictures and captions. Jim Rob McDonald" wrote in message ... What would you multi folks recommend as good "introductory" reading... |
#32
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Whats the deal with counter-rotating props?
I suspect that our perception of the dangers are skewed by the fact that
the failures (i.e. "second engine took them to the crash site") are reported in both the official records and the media, but we are less likely to hear about successful outcomes like yours. Rob "Michael" wrote in oups.com: ... The second engine, on failure of the first engine, will only lead you to a landing location, not necessarily of your choosing. My experience differs. When the left (critical) engine of my Twin Comanche failed (due to undetectable corrosion in the fuel servo) the remaining engine took me to a normal landing at an airport. Had I been in a single engine plane in the same situation, well, let's just say I was over Arkansas and there was an avtive airmet for mountain obscuration. Michael |
#33
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Whats the deal with counter-rotating props?
On the other hand, out here (central Ontario) most of the real estate does
not much exceed 1000' ASL. I have the Great Lakes on three sides and most of the territory I fly over when going any distance is trees, rocks, and small lakes - no emergency land sites, just crash sites. Even the 3800' SE ceiling of the Twinkie with the Robertson STOL kit would be enough to prevent an engine failure from ruining my day. Rob "BTIZ" wrote in news:auyDf.54832$V.15854@fed1read04: Out here, most airports are around 3000MSL, with terrain over 8000MSL between them, add in the density altitude factor on a standard 100F or higher day.. and that single engine is not going to be me to an airport. BT |
#34
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Whats the deal with counter-rotating props?
"Dico" wrote in message oups.com... Is there a web site that gives a good explanation as to why I want CR props. There are hundreds of the earlier model Twin Comanches flying without the CR props --- so what does someone with 300 hours single engine time need to worry about? What actually goes wrong? And when it does, what happens? I hear "critical engine" but it means very little to me. I would like to throw an interesting (if maybe false? I have no personal experience or a cite.) factoid into this discussion. I have read that the P38 Lightning was equipped with counter rotating props that rotated in the opposite (down going blades on outboard side of engines) from normal direction resulting in an aircraft with two critical engines and much increased yaw force when either engine failed. This was done despite control issues because it resulted in 15 knots extra top speed as compared with CR props using typical configuration (down going blade on inboard side of engines) Someone more knowledgeable may be able to explain why. |
#35
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Whats the deal with counter-rotating props?
Private wrote:
: I would like to throw an interesting (if maybe false? I have no personal : experience or a cite.) factoid into this discussion. : I have read that the P38 Lightning was equipped with counter rotating props : that rotated in the opposite (down going blades on outboard side of engines) : from normal direction resulting in an aircraft with two critical engines and : much increased yaw force when either engine failed. This was done despite : control issues because it resulted in 15 knots extra top speed as compared : with CR props using typical configuration (down going blade on inboard side : of engines) : Someone more knowledgeable may be able to explain why. Interesting. Perhaps less downward propwash on outboard ends of wings? Or maybe propwash vorticies "lifting" the fuselage rather than "swatting it down?" Just WAGs on my part. -Cory -- ************************************************** *********************** * Cory Papenfuss * * Electrical Engineering candidate Ph.D. graduate student * * Virginia Polytechnic Institute and State University * ************************************************** *********************** |
#36
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Whats the deal with counter-rotating props?
Private wrote:
I have read that the P38 Lightning was equipped with counter rotating props that rotated in the opposite (down going blades on outboard side of engines) from normal direction resulting in an aircraft with two critical engines and much increased yaw force when either engine failed. This is definitely true, in the sense that the props did counter-rotate opposite to what is now normal. However, the whole critical engine thing is way overrated. Vmc is a control speed, not a performance speed. It is quite a bit lower than Vyse, which is as slow as you ever want to fly with anything close to full power (other than in a training situation) whether you have an engine out or not. In other words, it's really not a big deal, which is why it's rare to see counter-rotating props in anything other than a trainer. This was done despite control issues because it resulted in 15 knots extra top speed as compared with CR props using typical configuration (down going blade on inboard side of engines) That doesn't sound right. My understanding is that the reason was to make the plane more maneuverable (using differential thrust for yaw). Of course you could get the same effect by using a bigger rudder, but that would mean more weight and drag, so maybe it boils down to the same thing - a cleaner, lighter, and thus faster airframe with the same maneuverability. It is also my understanding that the extra maneuverability was rarely used due to the complexity of engine management involved. Late in the game, a prototype was built with single-lever engine controls. Richard Bong, one of the most famous of the WWII aces, died test flying it when an engine blew up. Michael |
#37
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Whats the deal with counter-rotating props?
"Michael" wrote in message oups.com... snip Late in the game, a prototype was built with single-lever engine controls. Richard Bong, one of the most famous of the WWII aces, died test flying it when an engine blew up. Michael I thought he died in one of the first jets... perhaps a P-80? Joe Schneider 8437R ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#38
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Whats the deal with counter-rotating props?
"JJS" jschneider@remove socks cebridge.net wrote in message ... "Michael" wrote in message oups.com... snip Late in the game, a prototype was built with single-lever engine controls. Richard Bong, one of the most famous of the WWII aces, died test flying it when an engine blew up. Michael I thought he died in one of the first jets... perhaps a P-80? Correct. Fuel Pump failure (IIRC) which he did not know how to handle as he was too much the "hot shot" pilot to read the operating manual. Interestingly...both Bong and McConnell, the highest scoring aces in WW2 and Korea, both died right at the respective wars end while test flying, both in low altitude accidents. |
#39
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Whats the deal with counter-rotating props?
I suspect that our perception of the dangers are skewed by the fact that
the failures (i.e. "second engine took them to the crash site") are reported in both the official records and the media, but we are less likely to hear about successful outcomes like yours. Yes, that's part of it. My engine failure was under IFR, but while I reported it to ATC, that was as far as it went. I requested priority handling (not wanting to descend low over trees until I was closer to the airport) but that was as far as it went. After a throrough cleaning and flush of the fuel servo, I was back in action. There was no accident or incident. Engine failures do not figure heavily in the accident stats, but I've noticed that this is because single engine pilots are noticeably more conservative about flying in situations where an engine failure is likely to kill you. I think nothing of making an overwater flight dozens of miles from land, or a flight over rough terrain with widespread low IFR. I do it routinely in the twin. I will do it in a single, but only if I really need to make the flight. Michael |
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