John, Full stall was never reached due to the unexpected pitching up of the nose of the aircraft. I talked with Dr. Bennett of the Raspet Flight Research Lab. He experienced the same thing in a research aircraft several years age. The area of the wings of the "Marvel" research aircraft was increased without increasing the horizontal stabilizer proportionally. The same situation was noted. After increasing the area of the stabilizer, the problem ceased. Because of other modifications I made to the fuselage I may have helped create the problem. I will let you know what results I get from increasing the area of the horizontal stab. Thanks for you interest, Bill Page boliverp...@bellsouth.net
----- Original Message ----- From: "Steve Eberhart" <st...@newtech.com> To: "KRnet" <kr...@mylist.net> Sent: Thursday, April 13, 2006 6:34 PM Subject: Re: KR> Horizontal stab stall > Martindale Family wrote: > >>Hi Bill, >> >>Please elaborate on the Aerospace Department's conclusions. >> >>Seems to me a pitch up would occur in these circumstances only if the >>aircraft had its weight behind the CoG and that component is in excess of >>the lift available from the tailplane under forward stick. Obviously I'm >>missing something here and why isn't it reported from other Diehl wings >>currently flying. I agree, whatever it is it is potentially dangerous. >>Critically, does the nose actually drop at the stall itself after the >>pitch >>up immediately prior it? >> >>Cheers John >> >>John Martindale >>29 Jane Circuit >>TOORMINA NSW 2452 >>AUSTRALIA >> >>ph: 61 2 66584767 >>email: johnja...@optusnet.com.au >>website: www.members.optusnet.com.au/johnjanet/Martindale.htm >>----- Original Message ----- >>From: "countryhomeprint" <countryhomepr...@bellsouth.net> >>To: "KRnet" <kr...@mylist.net> >>Sent: Friday, April 14, 2006 6:47 AM >>Subject: KR> Horizontal stab stall >> >> >> >> >>>KR-netters >>> >>>After consulting with the Aerospace Department at Mississippi State >>>University concerning the pitching up of my KR-2 upon stall approach, a >>>probable cause has been reached. The Horizontal Stabilizer is stalling >>>prior to the wing stall. This may be caused by the longer wing by Dan >>>Deihl. This creates a very dangerous condition. There are three ways to >>>prevent this condition. (1) Increase the stabilizer area by increasing by >>>several inches the length of the stab. The standard flat stabilizer is >>>only about 50% as efficient as a stabilizer with a true airfoil which >>>leads to the 2nd method of prevention. (2) Change the stab airfoil to a >>>true airfoil which will increase the efficiency of the stab. And (3), >>>Don't stall the aircraft, keep the airspeed well above stall. >>>It has been noticed that some KR-2 builders constructed a true airfoil >>>rather than the flat stab shown in the plans. Maybe it should be noted to >>>other KR builders to do the same. >>>You guys who have true airfoil stabs, where did you get your plans, >>>technical info., etc. I would like to change my stab to a true airfoil. >>> >>>Maybe if I put Armorall on my horizontal stabilizer my problem will be >>>solved. >>> >>>I'm still finding dingle berrys after that close call. >>> >>> > The horiz. Stab. Langford has on his KR incorporates all of the > modifications you have described short of the Armorall dispenser. His > plane just keeps adding up flying hours. Don't know if it is proving > anything but it seems to be well mannered. He has engineering drawings > for all of the airfoils used on his plane. > > Steve Eberhart > > _______________________________________ > 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 >
