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#31
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Grubertm,
So what's the best procedure for a sand strip, 4000AGL, 50ft obstacle ? Don't go? Seriously, you probably want to get out of the sand ASAP. After that, you want to climb as best as you can, but that only gets important once you have left the ground. So, do the soft field procedure to start with. -- Thomas Borchert (EDDH) |
#32
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Mike
That's simple enough that every one should be able to understand. John `````````````````````````````````````````````````` ``````````` On Sat, 13 Aug 2005 04:05:57 GMT, "Mike Rapoport" wrote: Some flaps (maybe even full flaps) until airborn, accelerate in ground effect and then climb. If you are interested in this stuff, read F.E. Potts book on bush flying. Mike MU-2 "grubertm" wrote in message roups.com... So what's the best procedure for a sand strip, 4000AGL, 50ft obstacle ? I can see the advantage of 10 deg. flaps for a mud strip, but I am not sure whether the increased friction due to sand is worth the decrease in climb rate.. - Marco |
#33
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I believe that some 172s only have 30deg of flaps availible. Full flaps
produce *some* additional lift even if there is a large drag increase. Keep in mind that you are trading aerodynamic drag against the drag of the tires in sand. On my airplanes MU-2 and Helio Courier minimium ground roll is a function of weight, flaps and power availible. In the Helio: At normal density altitudes and light weights minimium ground roll is with full flaps (40deg). This use of full flaps increases obstacle clearance distance but reduces ground roll. At some high density altitude and high weight the airplane won't climb out of ground effect with full flaps without using a tremendous amount of distance and a reduced flap setting is required. The Helio is not that different from the 172 in terms of flaps. Both have single slotted fowler flaps. In the MU-2 Take off with flaps 20 uses less ground roll than flaps 5deg. Flaps 40deg used even less distance but isn't used because the airplane becomes airborn below Vmc and can't climb on one engine with flaps 40. My guess is that a 172 at light weights and low density altitude will use less runway with more than 10deg of flaps and the more powerful the engine the more pronounced this difference. It would be interesting to see if the new 172s have a full set of takeoff charts showing all altitudes, temps, weights and flaps settings Mike MU-2 "David Rind" wrote in message ... Mike Rapoport wrote: Some flaps (maybe even full flaps) until airborn, accelerate in ground effect and then climb. If you are interested in this stuff, read F.E. Potts book on bush flying. Mike MU-2 "grubertm" wrote in message oups.com... So what's the best procedure for a sand strip, 4000AGL, 50ft obstacle ? I can see the advantage of 10 deg. flaps for a mud strip, but I am not sure whether the increased friction due to sand is worth the decrease in climb rate.. - Marco I haven't been following this thread that closely so I may have missed something, but "full flaps"? I thought that once you got to 40 degrees of flaps on a 172 you were just adding drag without any appreciable reduction in stall speed. I can't see how that would get you into ground effect any quicker.... -- David Rind |
#34
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Okay, this post contradicts the previous post, and the way I learned it
is more like this post. .... but somewhere along the way, the 172 book changed from saying that 10 degrees would decrease climb performace, to indicating that it would increase climb performance (in terms of reduced distance to clear a 50 foot obstacle). When did the change occur? What physically changed on the aircraft? |
#35
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"Brien K. Meehan" wrote
Okay, this post contradicts the previous post, and the way I learned it is more like this post. ... but somewhere along the way, the 172 book changed from saying that 10 degrees would decrease climb performace, to indicating that it would increase climb performance (in terms of reduced distance to clear a 50 foot obstacle). When did the change occur? What physically changed on the aircraft? Bigger engine. When Lycoming upgraded the O-320 from 150 hp to 160 hp. The 1959 manual that I quoted reflected the 145 hp Continental O-300. I posted that data to refute George's post about "all 172's before 1964" used 20 degrees of flaps. Bob |
#36
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Michelle P wrote: In talking to another pilot who has an 172 L has states that his manual says if 10 degrees flaps are used it will decrease ground roll and decrease climb rate. Having an overall detrimental affect. The only definitive number the 172N manual states for flaps 10 degrees is Vx. First hand experience seems to confirm what the 172 L manual says. I fly an N-model and would agree with all of the above. In a soft-field situation there may be a moderate advantage to 10deg particularly at lighter loadings. Based on my runnings of the numbers though the difference looks likely to be lost in the detail. NB- 10 degrees is standard for a 172N on floats, which I suppose is the ultimate "soft field" situation. -cwk. |
#37
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Bob Moore wrote:
I posted that data to refute George's post about "all 172's before 1964" used 20 degrees of flaps. I did not mean that. What I meant was that any aircraft with manual flaps can get the shortest ground run by dumping in full flaps just above stall speed and hopping up into ground effect. All 172s prior to 1964 had manual flaps and can use this technique. George Patterson Give a person a fish and you feed him for a day; teach a person to use the Internet and he won't bother you for weeks. |
#38
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On Thu, 11 Aug 2005 00:26:56 GMT, Michelle P
wrote: An interesting dilemma. The manual for the 172 N tells you that 0-10 degrees is acceptable for takeoff. What do you all think? Michelle I hate giving an unscientific opinion, but piloting is a part of that. Every Cessna (150 through 337) that I've flown just "feels better" with 10 degrees of flaps on takeoff. Mike Weller |
#39
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Big John wrote:
[snip] Taxied out for a TO on R/W 21 (over 13K feet long). R/W 21 had a cross R/W about 4K down it. I released brakes and accelerated very slowly in the heat and altitude. When I hit the cross R/W there was a slight bump that threw me in the air and I caught it. Wasn't accelerating very fast so pulled the gear (flaps were still down 30 degrees) to reduce drag. Guess what, no climb (and no gear to land on remaining R/W). R/W heading was over Fort Bliss and I went over it about 5 feet above the TV antennas on the barracks (could count the elements on them) and just missed the flag pole. Next obstacle was the hill west of El Paso toward which I was pointed with a snow balls chance in hell of clearing. Used some rudder and gently skidded the nose toward the south enough to miss the hill. Was then over Mexico and dodging cactus and blowing sage brush. Started milking flaps up. Would get 25 or so feet altitude and retract flaps 2-3 degrees and when I sank would rotate the nose up to keep from hitting ground and again fly in ground effect. After about 20 miles into Mexico I got the flaps up and was able to gain a little airspeed which let me climb and accelerate. [snip] Ok, I never know whether to believe such stories or not. Here's a similar one I liked so much that I posted it on my blog: http://www.livejournal.com/users/clu...ter/25412.html -C. |
#40
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"Mike Rapoport" wrote in message nk.net... I believe that some 172s only have 30deg of flaps availible. Yes, P series only has 30°. -- Hello, my name is Mike, and I am an airplane addict.... |
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