KR> Re: Tri gear tail first on runway
4/6/2011, you wrote: >Very true statement Larry. I have slammed my tail on the runway more than >once and the tie down ring on my tail bears the wear to attest to the fact. >--- >Strange. >I have 335 hours on my KR2 tricycle, and NEVER hit the tail. >I can stall onto the runway, or drop the mains on the runway at 35 to 40 >kts. >Phil Matheson +++ I suspect the wing is not really "stalled" at that point and that your ASI is probably off by 10 to 15 knots at that AOA. You're simple descending to the runway from the flair at minimum airspeed. Same goes with a tail dragger touching tail first. An interesting test would be to measure the angle of the firewall in the three point position (tri-gear ). Then lower the tail to the ground and measure the firewall angle again. If the change is less then approx 14 degrees (plus your wing set AOA, the wing is not stalled with the tail touching. My tail dragger KR, with a 24 inch stretch over a standard KR, 30 inch Diehl gear, wing set at 3.5 degrees, has the wing at 12 degees in the 3 point attitude. Again, just one man's opinion. Larry Flesner -- Larry, I have a tri-gear plans-built KR-2 with standard Diehl gear. Stub wing is set at 3.5 degrees AOA in level attitude. With the tail skid pushed down 5 inches off the level concrete, my inclinometer shows an AOA of 14 degrees. With the tail skid on the concrete the AOA goes to 17.5 degrees. My conclusion: I would stall the wing before the tail skid touches the runway. Not accounted for is the low wing ground effect, static load on the gear and use of flaps on the above data versus actual flight performance. I suppose it would be possible to momentarily touch the skid to the runway by over controlling with PIO. Another possibility is planting the tail on the runway with max aft cg and full elevator deflection. I recall Boeing doing an over-rotation test on a 747 to prove to the FAA that the 747 was still flyable from the runway in that high AOA and aft cg situation. Boeing used a huge oak block bolted to the tail of the 747 as a skid. Hmm...maybe a little oak block would work on my KR-2. Another data point for my flight tests. Sid Wood Tri-gear KR-2 N6242, pimping for the DAR Mechanicsville, MD, USA smw...@md.metrocast.net
KR> Re: Tri gear tail first on runway.
I don't have a dog in this fight, but that is the way I also understand the stall. Angle of attack is the angle of the chord relative to the wind, not a horizontal line. So if the plane is descending in still air, the angle of attack will be greater than the attitude of the wing chord. . List-Post: krnet@list.krnet.org Date: Wed, 6 Apr 2011 20:23:23 -0500 From: "Mark" <markweg...@charter.net> Subject: RE: KR> Re: Tri gear tail first on runway. To: "'KRnet'" <kr...@mylist.net>, <virg...@bellsouth.net> Message-ID: Content-Type: text/plain; charset="iso-8859-1" The angle of attack is dependent on the 'relative wind' and has nothing to do with the wing chord reference to speed, attitude of the aircraft/airframe or anything else other than the relationship of the aerodynamic chord of the wing relative to the "relative wind". There are a number of publications, including FAA stuff, that explain the concepts (I bet Mark L can chime in here too) :) Mark W. N952MW
KR> Re: Tri gear tail first on runway.
At 07:55 PM 4/6/2011, you wrote: >The tail stall scared the out of my wife and I and she said not >to do that ever again, Like I would. >+ How did you identify the condition as a "tail stall"? What maneuver did you perform to induce a "tail stall", and how did you exit the maneuver? Seems like it would take considerable elevator deflection to create a "tail stall" and considerable elevator deflection at 115 mph would put one hell of a load on the wings. How many lives did you use up on that flight??? Larry Flesner
KR> Re: Tri gear tail first on runway.
The definition of an aerodynamic stall is when the critical angle of attack is exceeded. This was a big part of the private written exam. It's all about the angles and the effect that has on the airfoil. This is why the application of vortex generators make some aircraft (such as the 150) incredibly difficult to stall. With the vortex generators to keep the airflow from breaking up as quickly, there is not enough elevator authority to exceed the new critical angle of attack. This site explains the concept well: http://www.flightsimbooks.com/flightsimhandbook/CHAPTER_02_16_Basic_Aerodynamics.php This picture shows a hypothetical angle of attack vs critical angle of attack: http://zone.ni.com/cms/images/devzone/tut/ncezuttg46490.jpg " Angle of attack is the angle between the lifting body's reference line and the oncoming flow. " More simply put, the angle between the relative wind and the wing's reference line, which is shown in red in the picture I included. A stall at 115mph would be an 'accelerated stall', which occurs at a higher speed than your typical stall at 1g. You must've pulled back pretty hard or been very heavy. If you entered a spin, you were likely not coordinated. In order to get a tailplane stall you must either have had tailplane icing or a very aft CG condition. It's generally very difficult to impossible to accomplish. Regards, ~Matt On Wed, Apr 6, 2011 at 7:55 PM, Randy Smith <crz...@yahoo.com> wrote: > I am not an engineer but I always understood if there is not enough air > across the wing it is stalled. so what does the angle have to do with no air > across the wing? I know if you pull up and block the top of the wing it will > stall. I have stalled the wing at 105 mph and the tail at 115 mph. For your > information it was not on purpose and I do not suggest it. The wing stall > did not do much I just let it fall off on one side and after the second spin > I pulled it out. The tail stall scared the out of my wife and I and she > said not to do that ever again, Like I would. > > --- On Wed, 4/6/11, Virgil N. Salisbury <virg...@bellsouth.net> wrote: > > > From: Virgil N. Salisbury <virg...@bellsouth.net> > Subject: Re: KR> Re: Tri gear tail first on runway. > To: "KRnet" <kr...@mylist.net> > Date: Wednesday, April 6, 2011, 12:29 PM > > > Full stall requires ~13 Degrees Angle of Attack. What is your AOA > sitting on the ground ? If it is less than~13 Degrees, Then full stall > is NOT > possible. As Larry says" you are at the SLOWEST A/S possible > for landing ", Virg > > On 4/6/2011 4:37 AM, phillip matheson wrote: > > Very true statement Larry. I have slammed my tail on the runway more than > > once and the tie down ring on my tail bears the wear to attest to the > fact. > > --- > > > > Strange. > > > > I have 335 hours on my KR2 tricycle, and NEVER hit the tail. > > > > I can stall onto the runway, or drop the mains on the runway at 35 to 40 > > kts. > > > > Phil Matheson > > SAAA Ch 37 > > http://www.philskr2.50megs.com/ > > > > ___ > > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > > please see other KRnet info at http://www.krnet.org/info.html > > > > > > ___ > > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > > please see other KRnet info at http://www.krnet.org/info.html > > > > > ___ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > ___ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html >
KR> Re: Tri gear tail first on runway.
The angle of attack is dependent on the 'relative wind' and has nothing to do with the wing chord reference to speed, attitude of the aircraft/airframe or anything else other than the relationship of the aerodynamic chord of the wing relative to the "relative wind". There are a number of publications, including FAA stuff, that explain the concepts (I bet Mark L can chime in here too) :) Mark W. N952MW -Original Message- From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net] On Behalf Of Randy Smith Sent: Wednesday, April 06, 2011 7:55 PM To: virg...@bellsouth.net; KRnet Subject: Re: KR> Re: Tri gear tail first on runway. I am not an engineer but I always understood if there is not enough air across the wing it is stalled. so what does the angle have to do with no air across the wing? I know if you pull up and block the top of the wing it will stall. I have stalled the wing at 105 mph and the tail at 115 mph. For your information it was not on purpose and I do not suggest it. The wing stall did not do much I just let it fall off on one side and after the second spin I pulled it out. The tail stall scared the out of my wife and I and she said not to do that ever again, Like I would. --- On Wed, 4/6/11, Virgil N. Salisbury <virg...@bellsouth.net> wrote: From: Virgil N. Salisbury <virg...@bellsouth.net> Subject: Re: KR> Re: Tri gear tail first on runway. To: "KRnet" <kr...@mylist.net> List-Post: krnet@list.krnet.org Date: Wednesday, April 6, 2011, 12:29 PM Full stall requires ~13 Degrees Angle of Attack. What is your AOA sitting on the ground ? If it is less than~13 Degrees, Then full stall is NOT possible. As Larry says" you are at the SLOWEST A/S possible for landing ", Virg On 4/6/2011 4:37 AM, phillip matheson wrote: > Very true statement Larry. I have slammed my tail on the runway more > than once and the tie down ring on my tail bears the wear to attest to the fact. > --- > > Strange. > > I have 335 hours on my KR2 tricycle, and NEVER hit the tail. > > I can stall onto the runway, or drop the mains on the runway at 35 to > 40 kts. > > Phil Matheson > SAAA Ch 37 > http://www.philskr2.50megs.com/ > > ___ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > > > ___ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > ___ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html ___ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
KR> Re: Tri gear tail first on runway.
I am not an engineer but I always understood if there is not enough air across the wing it is stalled. so what does the angle have to do with no air across the wing? I know if you pull up and block the top of the wing it will stall. I have stalled the wing at 105 mph and the tail at 115 mph. For your information it was not on purpose and I do not suggest it. The wing stall did not do much I just let it fall off on one side and after the second spin I pulled it out. The tail stall scared the out of my wife and I and she said not to do that ever again, Like I would. --- On Wed, 4/6/11, Virgil N. Salisbury <virg...@bellsouth.net> wrote: From: Virgil N. Salisbury <virg...@bellsouth.net> Subject: Re: KR> Re: Tri gear tail first on runway. To: "KRnet" <kr...@mylist.net> List-Post: krnet@list.krnet.org Date: Wednesday, April 6, 2011, 12:29 PM Full stall requires ~13 Degrees Angle of Attack. What is your AOA sitting on the ground ? If it is less than~13 Degrees, Then full stall is NOT possible. As Larry says" you are at the SLOWEST A/S possible for landing ", Virg On 4/6/2011 4:37 AM, phillip matheson wrote: > Very true statement Larry. I have slammed my tail on the runway more than > once and the tie down ring on my tail bears the wear to attest to the fact. > --- > > Strange. > > I have 335 hours on my KR2 tricycle, and NEVER hit the tail. > > I can stall onto the runway, or drop the mains on the runway at 35 to 40 > kts. > > Phil Matheson > SAAA Ch 37 > http://www.philskr2.50megs.com/ > > ___ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > > > ___ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > ___ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
KR> Re: Tri gear tail first on runway.
Full stall requires ~13 Degrees Angle of Attack. What is your AOA sitting on the ground ? If it is less than~13 Degrees, Then full stall is NOT possible. As Larry says" you are at the SLOWEST A/S possible for landing ", Virg On 4/6/2011 4:37 AM, phillip matheson wrote: > Very true statement Larry. I have slammed my tail on the runway more than > once and the tie down ring on my tail bears the wear to attest to the fact. > --- > > Strange. > > I have 335 hours on my KR2 tricycle, and NEVER hit the tail. > > I can stall onto the runway, or drop the mains on the runway at 35 to 40 > kts. > > Phil Matheson > SAAA Ch 37 > http://www.philskr2.50megs.com/ > > ___ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > > > ___ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html >
KR> Re: Tri gear tail first on runway.
At 03:37 AM 4/6/2011, you wrote: >Very true statement Larry. I have slammed my tail on the runway more than >once and the tie down ring on my tail bears the wear to attest to the fact. >--- >Strange. >I have 335 hours on my KR2 tricycle, and NEVER hit the tail. >I can stall onto the runway, or drop the mains on the runway at 35 to 40 >kts. >Phil Matheson +++ I suspect the wing is not really "stalled" at that point and that your ASI is probably off by 10 to 15 knots at that AOA. You're simple descending to the runway from the flair at minimum airspeed. Same goes with a tail dragger touching tail first. An interesting test would be to measure the angle of the firewall in the three point position (tri-gear ). Then lower the tail to the ground and measure the firewall angle again. If the change is less then approx 14 degrees (plus your wing set AOA, the wing is not stalled with the tail touching. My tail dragger KR, with a 24 inch stretch over a standard KR, 30 inch Diehl gear, wing set at 3.5 degrees, has the wing at 12 degees in the 3 point attitude. Again, just one man's opinion. Larry Flesner
KR> Re: Tri gear tail first on runway.
Very true statement Larry. I have slammed my tail on the runway more than once and the tie down ring on my tail bears the wear to attest to the fact. --- Strange. I have 335 hours on my KR2 tricycle, and NEVER hit the tail. I can stall onto the runway, or drop the mains on the runway at 35 to 40 kts. Phil Matheson SAAA Ch 37 http://www.philskr2.50megs.com/ ___ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
