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#31
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Akaflieg Karlsruhe AK-X
Michael,
I am interested in the crosswind landing characteristics of flying wings, do you have any information on the discussed ships? The Genesis-2 has no problem landing in a crosswind, but as the forward speed slows to equal the crosswind speed, the ship turns into the wind and opposite rudder does nothing! After years of stopping on the runway, I deliberately started carrying an extra 10 knots of speed into the desired stopping area, then jump on the good hydraulic brake to stop the ship where desired. JJ |
#32
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Akaflieg Karlsruhe AK-X
On Wednesday, December 13, 2017 at 7:42:38 AM UTC-8, wrote:
Michael, I am interested in the crosswind landing characteristics of flying wings, do you have any information on the discussed ships? The Genesis-2 has no problem landing in a crosswind, but as the forward speed slows to equal the crosswind speed, the ship turns into the wind and opposite rudder does nothing! After years of stopping on the runway, I deliberately started carrying an extra 10 knots of speed into the desired stopping area, then jump on the good hydraulic brake to stop the ship where desired. JJ A steerable nose wheel would solve this problem. On my ASH26 Mi, I'd sooner give up the engine than the steerable tailwheel. |
#33
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Akaflieg Karlsruhe AK-X
On Wednesday, December 13, 2017 at 12:06:56 PM UTC-5, jfitch wrote:
On Wednesday, December 13, 2017 at 7:42:38 AM UTC-8, wrote: Michael, I am interested in the crosswind landing characteristics of flying wings, do you have any information on the discussed ships? The Genesis-2 has no problem landing in a crosswind, but as the forward speed slows to equal the crosswind speed, the ship turns into the wind and opposite rudder does nothing! After years of stopping on the runway, I deliberately started carrying an extra 10 knots of speed into the desired stopping area, then jump on the good hydraulic brake to stop the ship where desired. JJ A steerable nose wheel would solve this problem. On my ASH26 Mi, I'd sooner give up the engine than the steerable tailwheel. A steerable nose wheel would only work well, if the main wheel location is moved further back. RS |
#34
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Akaflieg Karlsruhe AK-X
On Wed, 13 Dec 2017 11:46:30 +0000 (UTC), Kiwi User
wrote: On Wed, 13 Dec 2017 01:27:16 +0100, Andreas Maurer wrote: Hi Andras, I'm rather worried about spanwise flow originating at the wing root (similar to the SB-13) - but let's wait and see. The guys (and gals) know their stuff. I notice that initial drawings put the wing at the bottom of the pilot's pod, but in the 1:2 model its just below the canopy rim. Was this for wing clearance or aerodynamics? Several causes: - mainly wing tip clearance: The wing tips are far behind the landing gear and dihedral is only 2 degrees, they come down when the nose goes up, creating ground clearance problems - with the wing out of the way lots of space for a really strong nose gear (one of the famous weak points of the SB-13) - the wing spar is now over the knees of the pilot, leaving plenty of easily accessible space for the controls, mixer and Haenle-type stick between wing spar and instrument panel - lots of space for the pilot (I'm 6'7" and fitedt comfortably in the prototype fuselage on the Aro aviation fair) In their own (German) words: https://akaflieg-karlsruhe.de/ak-x/aerodynamik/ I'm a little surprised, too, at the quite minimal root fairings. Is this what you were referring to when you mentioned spanwise flow at the root? Well, aerodynamically speaking there is no need for wing root fairings as long as the complete wing root is in an area of pressure rise. On a conventional glider the wing is in the area of pressure loss (aka: where the fuselage gets thinner), resulting in the need for a wing fairing. I'm not the designer of course, but I think you can be sure that we'll get to know all the details in the future. What I'm referring to can be seen on the SB-13: http://www.airport-data.com/aircraft...00724103.html# Look at the little red wing fences - afaik they had to be intruduced to tame handling (stall?) characteristics. (Bert: Dein Auftritt! Habe das SB-Buch gerade nicht vor mir, wo der genaue Grund beschrieben wurde). It would be interesting to see flow visualisation round them. Though, as you say, the guys and gals know their stuff, so maybe cleaning up the wing roots is being left for full size detailed design. After all, the 1:4 model had nothing except a couple of sensor probes at its root, so just adding the pod was quite a big step aerodynamically. Definitely. BTW: This is the project page of the AK-X 1/2 model: https://akaflieg-karlsruhe.de/tag/12-modell/ On the spin onboard video you can nicely see how the inner flaps work as elevator. |
#35
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Akaflieg Karlsruhe AK-X
On Wed, 13 Dec 2017 05:10:38 +0000, Michael Opitz
wrote: Martin Gregorie provided a pretty good link for a brief Horten history: https://scalesoaring.co.uk/VINTAGE/D.../Horten%20IV/H orten_IVb.html Thank you very much - extremely interesting lecture that I didn't know yet. Scheidhauer had flown most of the Horten types and despite some peculiarities, their handling had been generally benign as they were highly stall and spin resistant. Although the H IVa had been liable to flutter, it had proved possible to damp it by simultaneous use of the drag rudders. None the less, he had refused to fly an HIII to explore its handling at extreme rear centre of gravity positions. On 24 May 1944 he made the maiden flight of the ultra high aspect ratio H VI, discovering that not only was it subject to flutter at both high and low speeds but that the entire wing was far too flexible and fragile for even an expert pilot. Sounds.... interesting and exciting. Scheidhauer was a student of Dad's from the first military glider pilot training class at the DFS in ~1937 where Dad was one of the three original instructors. Dad also later got him a flight in a Me 163, even though he was from the Horten camp. By 1944 when Scheidhauer first flew the Ho VI, Dad was pretty deep into getting operational Me 163 units up and running. His glider logbook shows one or two Ho III entries earlier, but no Ho VI. He never really talked about the Ho VI at all. I doubt it flew much considering the info from the above story. This would be the next interesting topic in RAS: "What the test pilot thought about the Me-163 as a glider".... I don't know if they considered winglets, and I can't remember what the aircraft they designed after the war in Argentina looked like. The person to ask is Peter Selinger. He was also a friend of Scheidhauer's and received all of Scheidhauer's personal logs, etc when he passed away. Peter also wrote a book on the Hortens, but unfortunately, I don't have a copy of it. "Nurflügel", by Peter F. Selinger and Dr. Reimar Horten ISBN-103900310092 ISBN-139783900310097 I do have Peter's contact info in case you want it though. We have been in fairly regular contact with each other since 1985. Thank you very mich again - I'm aware of this book, but to be honest: I was always a little fascinated by the Horten gliders, but not enough to buy the book since I always thought their designs were some kind of one-trick-pony. The book is available on Amazon Germany - just tell me if I should get you a copy (how's your German?). Cheers Andreas |
#36
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Akaflieg Karlsruhe AK-X
On Wed, 13 Dec 2017 21:50:57 +0100, Andreas Maurer wrote:
Several causes: - mainly wing tip clearance: The wing tips are far behind the landing gear and dihedral is only 2 degrees, they come down when the nose goes up, creating ground clearance problems I didn't think of that. - with the wing out of the way lots of space for a really strong nose gear (one of the famous weak points of the SB-13) OK - the wing spar is now over the knees of the pilot, leaving plenty of easily accessible space for the controls, mixer and Haenle-type stick between wing spar and instrument panel Nice. What I'm referring to can be seen on the SB-13: http://www.airport-data.com/aircraft...00724103.html# Look at the little red wing fences - afaik they had to be intruduced to tame handling (stall?) characteristics. OK, understood. BTW: This is the project page of the AK-X 1/2 model: https://akaflieg-karlsruhe.de/tag/12-modell/ On the spin onboard video you can nicely see how the inner flaps work as elevator. Yes I found that this morning. Must be new: I've visited that page before but don't recall seeing it then. Fascinating to watch those inner flaps thinking they're on a canard! -- Martin | martin at Gregorie | gregorie | dot org |
#37
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Akaflieg Karlsruhe AK-X
On Wed, 13 Dec 2017 22:21:43 +0100, Andreas Maurer wrote:
If you're interested in the history of soaring and especially in fins detail of particular gliders its well worth bookmarking the Scale Soaring website: https://scalesoaring.co.uk Just don't be put off by its name! The in-depth documentation and photos of the gliders it does cover is excellent, e.g the Fafnir. However, its overall coverage isn't a patch on Martin Simon's "Sailplanes" three volume series: you'll definitely want them as well. The Scale Glider crowd rate them highly for his three-view drawings. -- Martin | martin at Gregorie | gregorie | dot org |
#38
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Akaflieg Karlsruhe AK-X
On Wed, 13 Dec 2017 21:46:06 +0000 (UTC), Kiwi User
wrote: On Wed, 13 Dec 2017 22:21:43 +0100, Andreas Maurer wrote: If you're interested in the history of soaring and especially in fins detail of particular gliders its well worth bookmarking the Scale Soaring website: https://scalesoaring.co.uk Just don't be put off by its name! The in-depth documentation and photos of the gliders it does cover is excellent, e.g the Fafnir. However, its overall coverage isn't a patch on Martin Simon's "Sailplanes" three volume series: you'll definitely want them as well. The Scale Glider crowd rate them highly for his three-view drawings. Well Martin, guess what's been robbing my time for the last couple of hours....... Brilliant website! Cheers Andreas |
#39
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Akaflieg Karlsruhe AK-X
At 21:21 13 December 2017, Andreas Maurer wrote:
On Wed, 13 Dec 2017 05:10:38 +0000, Michael Opitz wrote: Scheidhauer was a student of Dad's from the first military glider pilot training class at the DFS in ~1937 where Dad was one of the three original instructors. Dad also later got him a flight in a Me 163, even though he was from the Horten camp. By 1944 when Scheidhauer first flew the Ho VI, Dad was pretty deep into getting operational Me 163 units up and running. His glider logbook shows one or two Ho III entries earlier, but no Ho VI. He never really talked about the Ho VI at all. I doubt it flew much considering the info from the above story. This would be the next interesting topic in RAS: "What the test pilot thought about the Me-163 as a glider".... The Me 163 had an L/D of ~17, but the speeds were too high for any kind of thermal flight, especially for the heavy weaponized Me 163b version. Between the good L/D and ground effect, it was hard to get onto the ground in a reasonable distance until Dr Lippisch had Josef Hubert design under wing dive brakes for extra drag. Hubert also came up with the wing slots in front of the elevons to basically stop the tips from stalling at high AOA. Now, Dad did thermal a fully loaded (10 people) DFS 230 for up to an hour, and I heard that some of the passengers may have gotten a little airsick... Peter also wrote a book on the Hortens, but unfortunately, I don't have a copy of it. "Nurflügel", by Peter F. Selinger and Dr. Reimar Horten ISBN-103900310092 ISBN-139783900310097 Thank you very much again - I'm aware of this book, but to be honest: I was always a little fascinated by the Horten gliders, but not enough to buy the book since I always thought their designs were some kind of one-trick-pony. The book is available on Amazon Germany - just tell me if I should get you a copy (how's your German?). Right after I made that post, I found and bought a copy from an American seller. Danke für's Angebot. Auf Deutsch geht's mir auch noch recht gut....... Gruß, RO |
#40
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Akaflieg Karlsruhe AK-X
On 14/12/2017 07:50, Andreas Maurer wrote:
.... Several causes: - mainly wing tip clearance: The wing tips are far behind the landing gear and dihedral is only 2 degrees, they come down when the nose goes up, creating ground clearance problems Same reason as the dihedral on 707/DC-8, etc tailplanes I understand - with the wing out of the way lots of space for a really strong nose gear (one of the famous weak points of the SB-13) - the wing spar is now over the knees of the pilot, leaving plenty of easily accessible space for the controls, mixer and Haenle-type stick between wing spar and instrument panel Spar OVER the pilot's knees?? Sounds like emergency exits might be interesting - and not very rapid. - lots of space for the pilot (I'm 6'7" and fitedt comfortably in the prototype fuselage on the Aro aviation fair) In their own (German) words: https://akaflieg-karlsruhe.de/ak-x/aerodynamik/ -- GC |
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