KR> Thoughts and ideas on stretching the wingspan
That is known as a Gurney Flap, or wickerbill. It first appeared in Indy car racing on a Dan Gurney Car, thus the name. It is essentially a way to change the pressure differentials between two sides of an airfoil.. Do a google search on Gurney Flap and you'll find lots of information on it. -Jeff Scott - Original Message - From: Dene Collett Sent: 12/24/11 03:53 AM To: 'KRnet' Subject: RE: KR> Thoughts and ideas on stretching the wingspan Mark, on the Whisper motor glider, the wing has a very pronounced cusp on the underside and results in very high stick forces due to the size and length of the ailerons. Pilot fatigue is a major factor on longer flights. We have corrected this with trim tabs but as you know this just adds drag. What a few builders have done to alleviate these high stick forces is to install "gourney" tabs on the trailing edges of the ailerons. This is nothing more that a lip of approx just under 3/8" that sticks up at 90deg at the trailing edge on the top surface of the aileron. It can be trimmed until the desired stick forces are attained. Aparently they do not add any significand drag. All I know is that they do work. I have flown in a whisper equipped with them. Regards Dene Collett Avlec Projects cc Port Elizabeth South Africa To earn 100% commisions follow the link below: http://www.empowernetwork.com/almostasecret.php?id=Dene1 ___ 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> Thoughts and ideas on stretching the wingspan
Mark, on the Whisper motor glider, the wing has a very pronounced cusp on the underside and results in very high stick forces due to the size and length of the ailerons. Pilot fatigue is a major factor on longer flights. We have corrected this with trim tabs but as you know this just adds drag. What a few builders have done to alleviate these high stick forces is to install "gourney" tabs on the trailing edges of the ailerons. This is nothing more that a lip of approx just under 3/8" that sticks up at 90deg at the trailing edge on the top surface of the aileron. It can be trimmed until the desired stick forces are attained. Aparently they do not add any significand drag. All I know is that they do work. I have flown in a whisper equipped with them. Regards Dene Collett Avlec Projects cc Port Elizabeth South Africa To earn 100% commisions follow the link below: http://www.empowernetwork.com/almostasecret.php?id=Dene1
KR> Thoughts and ideas on stretching the wingspan
Dan Heath wrote: >>I think, and I know someone will correct me if I am wrong about this, that the RAF48 has a lower stall speed than does the "new wing".<< The one thing that was held constant when the new wing was developed was the lift coefficient (and therefore stall speed), so if the aircraft weighs the same, stall speed should be the same. The only downside to the "new wing" is that the aileron forces go up due to the cusp on the bottom of the trailing 25% of the chord. The resulting upward forces on the ailerons tighten up the linkages and cables, resulting in higher stick forces to turn at higher speeds. But as somebody put it to me"Is that a bad thing?". Maybe not, but it allows folks to claim a "lack of harmony" in aileron/elevator forces, not that there was any with the original RAF 48 airfoil, just more pronounced. "Fixing" the cusp leads to a lower lift coefficient, so don't do it... Mark Langford ML at N56ML.com website at http://www.N56ML.com
KR> Thoughts and ideas on stretching the wingspan
Hi Dan, I am in Lexington this week, are you willing to meet to look over the Blackbird? Bob McClure From: Dan Heath To: 'KRnet' Sent: Friday, December 23, 2011 6:04 AM Subject: RE: KR> Thoughts and ideas on stretching the wingspan I have the Diehl wing skins on my KR2. They are definitely "extended". I see NO issues with them. These extended wings have been flying for many years on many KR, both the 2 and 2S. Also, I understand that Mark L. has extended his wings with the new airfoil. Also, consider that when discussing the "design" limitations of the KR, that it has a "design" gross weight of something like 960 pounds or something near that. This plane is consistently flown at 1200 pounds gross, or more. I am not recommending that, but I know that many KR are coming in at near 800 pounds empty weight. Mine is 750 empty and fly's great with 185 pounds of me and 21 gallons of fuel. I think, and I know someone will correct me if I am wrong about this, that the RAF48 has a lower stall speed than does the "new wing". If you are shooting for "Light Sport", you will have to build it very light and will have to use the longer wings for a lower stall speed as there is no way you will even have a chance of getting there with the stock KR2 or 2S. Having said that, keep in mind that there is a very strong move by EAA and AOPA to allow another category of operation that will allow you to fly without having to get an FAA medical. That may take a while. You may want to consider building a plane that already meets the LSA category qualifications as you may spend a long time and a lot of money building a KR, only to find out that you cannot meet the stall speed requirement. See N64KR at http://KRBuilder.org - Then click on the pics See you at the 2012 - KR Gathering in Mt. Vernon, Il ? MVN ? 40th Anniversary There is a time for building and it never seems to end. Daniel R. Heath - Lexington, SC -Reply Message- DO NOT DO IT. The design was for what it is. Stresses calculated for the existing span. ___ 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> Thoughts and ideas on stretching the wingspan
I have the Diehl wing skins on my KR2. They are definitely "extended". I see NO issues with them. These extended wings have been flying for many years on many KR, both the 2 and 2S. Also, I understand that Mark L. has extended his wings with the new airfoil. Also, consider that when discussing the "design" limitations of the KR, that it has a "design" gross weight of something like 960 pounds or something near that. This plane is consistently flown at 1200 pounds gross, or more. I am not recommending that, but I know that many KR are coming in at near 800 pounds empty weight. Mine is 750 empty and fly's great with 185 pounds of me and 21 gallons of fuel. I think, and I know someone will correct me if I am wrong about this, that the RAF48 has a lower stall speed than does the "new wing". If you are shooting for "Light Sport", you will have to build it very light and will have to use the longer wings for a lower stall speed as there is no way you will even have a chance of getting there with the stock KR2 or 2S. Having said that, keep in mind that there is a very strong move by EAA and AOPA to allow another category of operation that will allow you to fly without having to get an FAA medical. That may take a while. You may want to consider building a plane that already meets the LSA category qualifications as you may spend a long time and a lot of money building a KR, only to find out that you cannot meet the stall speed requirement. See N64KR at http://KRBuilder.org - Then click on the pics See you at the 2012 - KR Gathering in Mt. Vernon, Il MVN 40th Anniversary There is a time for building and it never seems to end. Daniel R. Heath - Lexington, SC -Reply Message- DO NOT DO IT. The design was for what it is. Stresses calculated for the existing span.
KR> Thoughts and ideas on stretching the wingspan
On Dec 22, 2011 4:24 PM, "Virgil N. Salisbury" wrote: > > >DO NOT DO IT. The design was for what it is. Stresses >calculated for the existing span. How much of a test pilot >and designer do you want to be ? Virg I do plan on redoing the analysis on the wings, fuselage, and spars. I was wondering if others had traveled down this path before and what their numbers were. According to my plans, the gross weight is specified to be 900# but many of the weight and balance sheets I see have gross weights 2-300# higher. How do they/we/I justify this? If we can safely increase the gross, we should be able to trade gross for some wingspan. I don't plan on doing anything unless the numbers tell me I can. -mdg
KR> Thoughts and ideas on stretching the wingspan
DO NOT DO IT. The design was for what it is. Stresses calculated for the existing span. How much of a test pilot and designer do you want to be ? Virg On 12/22/2011 12:16 PM, Mark Goldman wrote: > I'm about to start construction of a KR-2S but I'm likely to be limited to > light sport. Bearing this in mind, I would like to reduce my stall speed. > I was wondering, does anyone out there have experience with stretching the > wingspan? > > Thoughts? Ideas? > > -mdg > ___ > 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> Thoughts and ideas on stretching the wingspan
I'm about to start construction of a KR-2S but I'm likely to be limited to light sport. Bearing this in mind, I would like to reduce my stall speed. I was wondering, does anyone out there have experience with stretching the wingspan? Thoughts? Ideas? -mdg
