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#1
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or fantasy of flight?
On page 52 of the September issue of Soaring magazine Jim Payne is listed as having flown an out and return course of 300 km at an average speed of an amazing ground speed of 189.62 MPH ! Can someone please explain how he did this when the Vne of the Arcus M is 174 MPH. It seems to me the only way to do this is to somehow fly (at Vne the entire flight),downwind, on both out and return legs. |
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On Tuesday, September 20, 2016 at 7:01:26 PM UTC-6, Soartech wrote:
or fantasy of flight? On page 52 of the September issue of Soaring magazine Jim Payne is listed as having flown an out and return course of 300 km at an average speed of an amazing ground speed of 189.62 MPH ! Can someone please explain how he did this when the Vne of the Arcus M is 174 MPH. It seems to me the only way to do this is to somehow fly (at Vne the entire flight),downwind, on both out and return legs. Wave and altitude kick. Remember the higher you fly your TAS increases. That"s why speed and distance folks fly the great basin. Crusing at 16-18 thousand gets you a 30 Kt kick in TAS. Here's his story from the OLC. Best. #711. ___________ Pilot: Co-pilot Miguel Iturmendi. Mission was to fly a declared 300 km out-and-return between Inyokern and Big Pine. The forecast said the wave would be weak early with winds and lift increasing in the late afternoon. During the first lap, the wave was not good between Cindercone and Manzanar....the turn was covered in cloud. During the second lap, the lift was better...the speed was 278 kph. By the third lap, the lift was ripping and the clouds much better...the speed was 305.12 kph (189.62 mph)... Late in the day the Antelope Valley was overcast. We descended through a large hole in the overcast near California City. Had a Sage 2 clearance to FL290 in R-2508. For photos see www.tumblr.com/SoaringBlog. Thanks, Cindy for coordinating the Sage 2; Joshua for the outstanding service; and Doug T, Greg, Beth, & Jackie for crewing. |
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Link doesn't work for me
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On Wednesday, September 21, 2016 at 8:28:43 AM UTC-7, Duster wrote:
Link doesn't work for me http://soaringblog.tumblr.com/ |
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![]() Wave and altitude kick. Remember the higher you fly your TAS increases. That"s why speed and distance folks fly the great basin. Crusing at 16-18 thousand gets you a 30 Kt kick in TAS. Here's his story from the OLC. Best. #711. Tom, Thanks for the explanation. I recalled it as the other way around. |
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On Tuesday, September 20, 2016 at 9:01:26 PM UTC-4, Soartech wrote:
or fantasy of flight? On page 52 of the September issue of Soaring magazine Jim Payne is listed as having flown an out and return course of 300 km at an average speed of an amazing ground speed of 189.62 MPH ! Can someone please explain how he did this when the Vne of the Arcus M is 174 MPH. It seems to me the only way to do this is to somehow fly (at Vne the entire flight),downwind, on both out and return legs. A rule of thumb under standard conditions is about 2%/thousand feet increase in True Airspeed. So, if you're indicating 100kts at 10% feet you're actually doing closer to 120kts over the ground in still air. Now, the problem kicks in with flutter and aeroelasticity, so the VNE (indicated) decreases with altitude in most gliders. I'll leave it at that, since it's been more than 30 years since my last problem set on that topic :-) P3 |
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On 21/09/2016 03:24, Tom Kelley #711 wrote:
On Tuesday, September 20, 2016 at 7:01:26 PM UTC-6, Soartech wrote: or fantasy of flight? On page 52 of the September issue of Soaring magazine Jim Payne is listed as having flown an out and return course of 300 km at an average speed of an amazing ground speed of 189.62 MPH ! Can someone please explain how he did this when the Vne of the Arcus M is 174 MPH. It seems to me the only way to do this is to somehow fly (at Vne the entire flight),downwind, on both out and return legs. Wave and altitude kick. Remember the higher you fly your TAS increases. That"s why speed and distance folks fly the great basin. Crusing at 16-18 thousand gets you a 30 Kt kick in TAS. Here's his story from the OLC. Best. #711. Pilot: Co-pilot Miguel Iturmendi. Mission was to fly a declared 300 km out-and-return between Inyokern and Big Pine. The forecast said the wave would be weak early with winds and lift increasing in the late afternoon. During the first lap, the wave was not good between Cindercone and Manzanar...the turn was covered in cloud. During the second lap, the lift was better...the speed was 278 kph. By the third lap, the lift was ripping and the clouds much better...the speed was 305.12 kph (189.62 mph)... Late in the day the Antelope Valley was overcast. We descended through a large hole in the overcast near California City. Had a Sage 2 clearance to FL290 in R-2508. For photos see www.tumblr.com/SoaringBlog. Thanks, Cindy for coordinating the Sage 2; Joshua for the outstanding service; and Doug T, Greg, Beth, & Jackie for crewing. Hats off to the pilots for their performance. But the above looks a bit extreme. So I did some checking. Google found me a copy of the "Flight Manual for Powered Sailplane, Arcus M" at http://www.schaenis-soaring.ch/filea..._M_AFM_ENG.pdf Around page page 38 of that document is a table listing Max permitted speed verses altitude. I listed 3 points in their hight band below and used my old circular flight computer to find the TAS at each of the altitude. Altitude (m) VNE (km/h) TAS (km/h) 7000 220 318 8000 207 320 9000 195 318 There is obviously a pattern above. To achieve an average cross country speed of 305km/h must have required operating right on the edge of the envelope for the entire flight. Ian |
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On Thursday, September 22, 2016 at 9:10:35 AM UTC+12, Ian wrote:
On 21/09/2016 03:24, Tom Kelley #711 wrote: On Tuesday, September 20, 2016 at 7:01:26 PM UTC-6, Soartech wrote: or fantasy of flight? On page 52 of the September issue of Soaring magazine Jim Payne is listed as having flown an out and return course of 300 km at an average speed of an amazing ground speed of 189.62 MPH ! Can someone please explain how he did this when the Vne of the Arcus M is 174 MPH. It seems to me the only way to do this is to somehow fly (at Vne the entire flight),downwind, on both out and return legs. Wave and altitude kick. Remember the higher you fly your TAS increases. That"s why speed and distance folks fly the great basin. Crusing at 16-18 thousand gets you a 30 Kt kick in TAS. Here's his story from the OLC. Best. #711. Pilot: Co-pilot Miguel Iturmendi. Mission was to fly a declared 300 km out-and-return between Inyokern and Big Pine. The forecast said the wave would be weak early with winds and lift increasing in the late afternoon. During the first lap, the wave was not good between Cindercone and Manzanar...the turn was covered in cloud. During the second lap, the lift was better...the speed was 278 kph. By the third lap, the lift was ripping and the clouds much better...the speed was 305.12 kph (189.62 mph)... Late in the day the Antelope Valley was overcast. We descended through a large hole in the overcast near California City. Had a Sage 2 clearance to FL290 in R-2508. For photos see www.tumblr.com/SoaringBlog. Thanks, Cindy for coordinating the Sage 2; Joshua for the outstanding service; and Doug T, Greg, Beth, & Jackie for crewing. Hats off to the pilots for their performance. But the above looks a bit extreme. So I did some checking. Google found me a copy of the "Flight Manual for Powered Sailplane, Arcus M" at http://www.schaenis-soaring.ch/filea..._M_AFM_ENG.pdf Around page page 38 of that document is a table listing Max permitted speed verses altitude. I listed 3 points in their hight band below and used my old circular flight computer to find the TAS at each of the altitude. Altitude (m) VNE (km/h) TAS (km/h) 7000 220 318 8000 207 320 9000 195 318 There is obviously a pattern above. To achieve an average cross country speed of 305km/h must have required operating right on the edge of the envelope for the entire flight. Ian The police won't come knocking on your door if you exceed the "permitted" speed. They're designed to 40% (?) above Vne and test flown to 20% (?) over. Yes, exceeding the Vne printed in the manual makes you a test pilot. That's part and parcel of world record flying. Don't try it at home. |
#9
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Every glider flight manual I studied made it clear that the flight tested limits laid out applied up to 3000 meters ... over that you are relying on a combination of theory, over-design, excessive build over required standards, and it always seemed to me good fortune. I have no idea if such applied to the Arcus M used by Payne.
On Tuesday, September 20, 2016 at 9:01:26 PM UTC-4, Soartech wrote: or fantasy of flight? On page 52 of the September issue of Soaring magazine Jim Payne is listed as having flown an out and return course of 300 km at an average speed of an amazing ground speed of 189.62 MPH ! Can someone please explain how he did this when the Vne of the Arcus M is 174 MPH. It seems to me the only way to do this is to somehow fly (at Vne the entire flight),downwind, on both out and return legs. |
#10
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Jim's a retired USAF test pilot, so I'm sure understands all the intricacies of flying near Vne.
I'm not an aerodynamicist so here's my lay understanding. A glider's Vne is the true airspeed as indicated IAS at typically 3000m. If I recall, my ASH-26E redline was 146 KIAS which worked out to 160-ish TAS. The chart Schleicher provides for Vne above 3000m drops the IAS to keep the TAS at or below 160. My ASW-27 chart is: 10K 151 knots 16.5K 133 knots 23K 119 knots etc... In the '26 I flew a 100 km triangle in wave between 14 and 18K MSL so limited my IAS to a conservative 120 knots, which I maintained nearly the whole time. The achieved speed for the triangle was a bit over 130 knots. So TAS is your friend even below 18K! If repeating this in the '27 I would again use 120 as a "safe" Vne for below 18K. 5Z On Wednesday, September 21, 2016 at 6:59:10 PM UTC-7, howard banks wrote: Every glider flight manual I studied made it clear that the flight tested limits laid out applied up to 3000 meters ... over that you are relying on a combination of theory, over-design, excessive build over required standards, and it always seemed to me good fortune. I have no idea if such applied to the Arcus M used by Payne. |
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