From: owner-krnet-l-digest@lists.teleport.com (krnet-l-digest) To: krnet-l-digest@lists.teleport.com Subject: krnet-l-digest V1 #48 Reply-To: krnet-l-digest Sender: owner-krnet-l-digest@lists.teleport.com Errors-To: owner-krnet-l-digest@lists.teleport.com Precedence: bulk krnet-l-digest Tuesday, June 24 1997 Volume 01 : Number 048 ---------------------------------------------------------------------- Date: Mon, 23 Jun 1997 14:35:41 -0700 From: Micheal Mims Subject: Re: KR: NTSB Report At 03:49 PM 6/23/97 -0400, you wrote: Boy I hope you guys don't get too fed up with my references to >the Sonerai. It's what I fly and I have real world experience with the >airplane and the same VW the KR uses Gee I hope not either, this is the same reason I reference the Dragonfly so much, it has the same VW based powerplant. I noticed from the NTSB reports that a few canopies have departed during flight which resulted in a off airport landing. (KR will not fly without canopy) This seems to be a problem with the piano hinge installation. I know I have seen canopies installed with wood screws so during my lunch break I checked the plans and sure enough it says to use BOLTS to attach the hinge halves to the longeron and canopy sill! If your canopy is installed with wood screws I would do an airframe change pronto! Boy some of the stuff in the reports seems just plain silly but I guess it happens. Interesting note; I huge portion of the incidents were people trying to turn back to the runway after departure. The FAA continually says not to do this, I wonder why? On one of the non-recoverable spin incidents the CG was found to be way aft of published max range and over gross by 190+ pounds. What's going through a persons head when he knows he's heavy and aft but still decides to demonstrate the stall characteristics of an airplane? A few incidents involved the pilots making the decision to takeoff even when the engine was running rough and making less than 100% power! Why? Why would a person put a rubbermaid container in the passenger seat and use a squeeze bulb and clear vinyl tubing as a fuel system? Why would a person purchase a used mag, install it (single mag ignition) and go flying without having it checked out or at least checking it himself? It was good that no structural failures were involved in any accidents, of the incidents that involved control failures there was not enough information to place blame on the KR or the possible use ACE hardware! Jumping off soap box now! GERONAMOOOooooooo..................!!!! ________________________________ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Micheal Mims Just Plane Nutts mailto:mimsmand@ix.netcom.com http://www.netcom.com/~mimsmand ------------------------------ Date: Mon, 23 Jun 1997 19:42:22 EDT From: jscott.pilot@juno.com (Jeffrey E. Scott) Subject: KR: More test results KRNetters, As some people have expressed an interest in keeping up with the flight testing of N1213W, I'll continue postings as I get the bugs ironed out. Initially, this plane didn't have enough nose up trim. Even with full up trim, it wanted to go about 130+ mph. I was concerned that it might take a great deal of retrimming to get this plane to fly correctly. Yesterday I installed a wedge underneath the trailing edge of the right elevator. The wedge measured 1 inch high, 2 inches long, and 12 inches wide. On this morning's test flight I found that full nose up trim brought the speed down to ~60 mph, while about midpoint of the trim brought around 135 mph. Although the trim seems to be a bit senistive, which matches the sensitivity of the elevator, the plane will now fly hands off at a given trim and power setting. Next step will be to trim out the rudder as it needs a small amount of right rudder trim added to it. The right wing also seems a bit heavy at times, but I doubt that I will need to retrim it. It seems to be very sensitive to fuel loading as I have a fuel tank in either wing (as well as the header). Just a shift of a couple of gallons of fuel seems to even out the load. The meter now shows 8.5 hours on the airframe. 5+ hours of that are air time with the rest having been spent doing the ground testing. If all continues well, I should be able to attend Perry with it. Jeff Scott Los Alamos, NM - ---- Jeffrey Scott jscott.pilot@juno.com See construction of KR-2S N1213W at http://fly.hiwaay.net/~langford/kjeffs.html - ---- ------------------------------ Date: Mon, 23 Jun 1997 17:32:07 -0700 From: Ted & Louisa Jones Subject: Re: KR: NTSB Report Micheal Mims wrote: > > I just read through the NTSB reports and if there is anyone out there who > wants to argue about the sensitivity of the KR controls and or possible aft > CG problems, I know where to send them!! > > Just read about all the PIO's, over controling and unrecoverable spins! > > ________________________________ > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Micheal Mims > Just Plane Nutts > mailto:mimsmand@ix.netcom.com > > http://www.netcom.com/~mimsmand Sobering reading. Now if we could just skip that first flight and go right on to the second. . . . Thanks Rick. Ted Jones ------------------------------ Date: Mon, 23 Jun 1997 20:10:17 -0400 (EDT) From: BSHADR@aol.com Subject: Re: KR: Re: Computer geek info In a message dated 97-06-23 19:22:59 EDT, you write: << How did this shit get here? I get enough of that on my DND account. >> Sorry Cary...Now how 'bout you let it all out and tell me how you really feel.... :-( Randy Stein (Supersonic "send" key clicker and general idiot - now with an unlisted forwarding address...) BSHADR@aol.com ------------------------------ Date: Mon, 23 Jun 1997 18:52:04 -0700 From: MARVIN MCCOY Subject: Re: KR: EAA Northwest Fly-in, Arlington, WA. TANDEM2@aol.com wrote: > > marvin, trying to set up for sunday, same place, same time, only time i can > be there, would like to meet everyone > john - -------- Saturday or Sunday is OK for me. DON is that OK by you. Anyone have a problem with Sunday at 9:00am. If not lets do it on Sunday the 13th. Marvin McCoy Seattle, WA. North end of Boeing Field Mr.Marvin@worldnet.att.net - ------------ ------------------------------ Date: Mon, 23 Jun 97 20:59:00 PDT From: Scott DeLong Subject: KR: remove Kat: For your info and to share with your new computer geek guys... Subj: Only $799! P133 computer/16RAM/1.2GIG/6xCD Date: 97-06-22 07:36:19 EDT From: computer284@xqkq.netsales1.net (P133 Computer) Reply-to: computer3@netsales1.net To: computer284@xqkq.netsales1.net Only $799! P133 computer/16RAM/1.2GIG/6xCD Top quality peripherals and components are built into these high quality computers, such as USR, Toshiba, Mistumi, Samsung, Asus, etc. By ordering them over the internet, you can save a lot of money, and still get the absolute best quality. Go see for yourself at GreatDe als.Net. AMD K5-133 mhz desktop ... Only $799 computer (comparable to the Pentium) with Asus motherboard, 256k pipelined burst cache, 16 meg EDO RAM, Path Trio 64 bit 1 meg video card, 1.2 gig Samsung Hard Disk, 1.44 Mitsumi floppy drive, 6x Toshiba CD-ROM drive, 16 bit Creative Labs Soundblaster sound card, Mini Tower case, Mitsumi mouse, Mitsumi Windows 95 101 keyboard, Windows 95 CD installed, '97 Groliers Multimedia Encyclopedia, Netscape Navigator 3.0, Webtalk with microphone, and over 20 full software titles. One year warranty. Monitor is not included in this price, but we have a 14" analog for $179, 15" digital for $219, and 17" digital for only $399! Pentium 133/16RAM/2.1GIG/2meg video/33.6 voice USR modem ... only $999 Intel chipset Pentium 166/16RAM/2.1GIG/2meg video/33.6 USR voice modem ... only $1199 Intel chipset Pentium 200/32RAM/2.1GIG/2meg video/33.6 USR voice modem ... only $1499 Intel chipset Major OEM software titles, such as Lotus SmartSuite '97 for only $99 and many others, when you buy a computer. A variety of LabTech speakers also avaialble. There is a limited supply of these. So, first come, first serve. Order online at http://www.gre atdeals.net If you do not wish to receive any more notifications of great deals like this, just type REMOVE in the subject line and reply, and we'll take you off of our mailing list. ------------------------------ Date: Mon, 23 Jun 1997 22:58:53 -0400 (EDT) From: Outahan@aol.com Subject: Re: KR: EAA Northwest Fly-in, Arlington, WA. Guys: I'll be camping up there Friday - Sunday - would love to hook up with you. I don't remember the campfire local but I'll find it. If you see a guy 'bout 5' 9", stocky build with a left arm in a sling, wearing a red Avid hat (I REALLY don't like the RR chapeau), I'll be me. Say "hi". Scott Bailey ------------------------------ Date: Mon, 23 Jun 1997 23:25:24 -0700 From: "David M. Gargasz" Subject: Re: KR: Revmaster for sale Brian Bland wrote: > > On Mon, 16 Jun 1997 21:51:37 -0700, you wrote: > > >Hi John, > >Iv tried to get my hands on Molt Taylors design criteria on the TPG > >system, the kraft paper and glass composite system. I'd like to adapt > >its use in leiu of plywd on the kr2 boat, the bullet came in the 600 lb. > >wieght range, the tpg system adapted to the kr2 would lighten up the > >finished product. Any information as to the TPG system would be very > >much appreciated, thank you! > >Gene Gargasz % dave@erienet.net > > Gene, > > Have you read Composite Construction For Homebuilt Aircraft by Jack > Lambie? > > It has a chapter on the TPG system. I don't know for sure what you > are looking for but it discusses this system. If you haven't read > this book and want to read what it has to say let me know and I will > send you a copy or just type it up and e--mail it to you. > > Brian J Bland > Claremore, OK > > Widened & stretched KR-2s (KR-2ss?) Hi Brian, It was in a 80's Jack Lambie book that got my attention about the TPG system, the only thing that turned me off the bullet design was the drive shaft that ran through the length of the plane approx. 15' long the possibility of containing it in a stable position in a turbelant air would always be a constant worry for me. This shaft @ 2500 rpm next to the pilot breaks would cut the craft in half, My son was on an old ac wd tractor with a mower on it when the mower drive shaft connected to the pto broke it went through the shaft gard just missed him the shaft was turning 1200 rpm driven by a 40 hp tractor. Proably the reason for 6 hr. rev.. The bullet materials had to take the stress of the enjine in the nose and the stress of the prop drive train in the rear, the tpg system came in @ 600 + lbs.. I believe it could be adapted to the kr2 using the the wood frame and ending up with a lighter stronger kr2. The tpg system was a joint venture with some western lumber asso. and I'm shure there are the research records as to the structural values of of the finished product, that is the info I'd like to get a hold of. thanks Gene Gargasz, Elyria Ohio ------------------------------ Date: Mon, 23 Jun 1997 23:46:37 -0400 (EDT) From: Dennis Ambrose Subject: KR: REMOVE At 02:35 AM 6/23/97 -0400, you wrote: > >Kat: > >For your info and to share with your new computer geek guys... > >Subj: Only $799! P133 computer/16RAM/1.2GIG/6xCD >Date: 97-06-22 07:36:19 EDT >From: computer284@xqkq.netsales1.net (P133 Computer) >Reply-to: computer3@netsales1.net >To: computer284@xqkq.netsales1.net > > Only $799! P133 computer/16RAM/1.2GIG/6xCD > > Top quality peripherals and components are built into > these high quality computers, such as USR, Toshiba, > Mistumi, Samsung, Asus, etc. > > By ordering them over the internet, you can save a lot > of money, and still get the absolute best quality. > Go see for yourself at GreatDe >als.Net. > > AMD K5-133 mhz desktop ... Only $799 > > computer (comparable to the Pentium) with Asus > motherboard, 256k pipelined burst cache, 16 meg > EDO RAM, Path Trio 64 bit 1 meg video card, 1.2 > gig Samsung Hard Disk, 1.44 Mitsumi floppy drive, > 6x Toshiba CD-ROM drive, 16 bit Creative Labs > Soundblaster sound card, Mini Tower case, Mitsumi > mouse, Mitsumi Windows 95 101 keyboard, Windows 95 > CD installed, '97 Groliers Multimedia Encyclopedia, > Netscape Navigator 3.0, Webtalk with microphone, > and over 20 full software titles. One year warranty. > Monitor is not included in this price, but we have > a 14" analog for $179, 15" digital for $219, and > 17" digital for only $399! > > Pentium 133/16RAM/2.1GIG/2meg video/33.6 voice USR modem > ... only $999 Intel chipset > > Pentium 166/16RAM/2.1GIG/2meg video/33.6 USR voice modem > ... only $1199 Intel chipset > > Pentium 200/32RAM/2.1GIG/2meg video/33.6 USR voice modem > ... only $1499 Intel chipset > > Major OEM software titles, such as Lotus SmartSuite '97 for > only $99 and many others, when you buy a computer. A variety > of LabTech speakers also avaialble. > > There is a limited supply of these. So, first come, first > serve. > > Order online at http://www.gre >atdeals.net > > If you do not wish to receive any more notifications of > great deals like this, just type REMOVE in the subject > line and reply, and we'll take you off of our mailing list. > > > > ------------------------------ Date: Tue, 24 Jun 1997 02:13:05 -0400 (EDT) From: DC4FREE@aol.com Subject: Re: KR: EAA Northwest Fly-in, Arlington, WA. Arlington will be a blast this year. The Confederate Air force will be there with WWII bombers we can crawl thru. Lots of homebuilts (100’s) showed up last year and you should have seen the bright red Stinson (sp), the skin was so smooth you could hardly find the seams. I had several great rides in the Avid Magnum, what a plane, almost traded off my KR-2 for it; but since I’ve only got the top half left to do (turtle deck, fore deck, canopy, engine and mounts and the cowling oh yes endless sanding filling sanding filling sanding filling..........) came to my senses. See ya at Arlington Don Wright Everett, WA. DC4FREE@AOL.COM ------------------------------ Date: Mon, 23 Jun 1997 23:15:42 -0700 From: wolfpacks@juno.com (Linda & Paul Martin) Subject: Re: KR: EAA Northwest Fly-in, Arlington, WA. Real, live KRs in Arlington...I'll be there. Sat. or Sunday for a gathering is fine with me. Paul M. Ashland, OR ------------------------------ Date: Tue, 24 Jun 1997 02:24:13 -0400 (EDT) From: DC4FREE@aol.com Subject: Re: KR: EAA Northwest Fly-in, Arlington, WA. I'll be there the whole 5 days, I'm babysitting some Boy Scouts that help out at Arilngton for a service project. Sunday is as good as any other day----- same time and place (0900 hrs by the ultralight cafe, firepit is in front of the cafe) Don Wright Everett, WA Near Martha Lake Airport DC4FREE@AOL.COM In a message dated 97-06-23 23:23:52 EDT, you write: << TANDEM2@aol.com wrote: > > marvin, trying to set up for sunday, same place, same time, only time i can > be there, would like to meet everyone > john -------- Saturday or Sunday is OK for me. DON is that OK by you. Anyone have a problem with Sunday at 9:00am. If not lets do it on Sunday the 13th. Marvin McCoy Seattle, WA. North end of Boeing Field Mr.Marvin@worldnet.att.net ------------ >> ------------------------------ Date: Sun, 22 Jun 1997 13:42:22 -0700 From: Donald Reid Subject: Re: KR: Hinge Material David Moore wrote: > > I haven't done anything lately to stir-up the pot so here it goes, Do any > of you areo-nautical engineer types tell me what the tensile strength of > one of these aluminum hinges on the rudder and elevator would be if they > are using a 3/16" bolt as a hinge? > Now consider it is held on by two 3/16" bolts through a 5/8" wooden spar, > with a doubler. Now of course the weakest part is probably the spar. > I did a little calculating and have a few answers. The stabilizer will safely carry about 540 lbs with an ultimate load limit of 948 lbs, using a standard semi-eliptic load distribution. This represents an FAR part 23 yield load limit of slightly greater than 6 G's at 900 lb gross weight. Assuming the elevator hinges are made from 6061T6 and are 1 inch wide, 0.125 inch thick, the hinge bolt is in the center of a 0.5 inch radius lug, and built to acceptable standards of quality, then ONE lug will have the following failure loads (Ultimate) Tension = 4265# (hinge lug tears apart) Bearing = 2065# (material at the bolt deforms around the bolt) bolt hole shear = 2742# (hinge bolt pulls through the hinge lug) If a 5/16" OD bushing is installed in the hinge lug, the failure loads (Ultimate) become: Tension = 3609# Bearing = 3438# bolt hole shear = 2320# A 3/16" aircraft bolt will carry about 2070# in single shear. There are six hinge lugs, so multiple the individual failure load by 6 to get the total failure load. There are three bolts, so multiply by three to get the total failure load on the bolts. The yield load in about 2/3 of the ultimate load. This represents the upper limit before a permanent change is seen in the material. There is also a cyclical failure mode caused by fatigue. This is similar to bending a paperclip back forth until it breaks. In round numbers, if you keep the working loads less than 10 percent of the yield load, then fatigue limits won't be a problem. If you are still awake after all this, the hinges are a lot stronger than the spars and I think the spars are strong enough. This is just a rough approximation of the stuff a designer has to go through. - -- Don Reid (Somewhere in central Virginia) donreid@erols.com ------------------------------ Date: Tue, 10 Jun 1997 00:21:56 +1000 From: ginnwj Subject: Re: KR: High Speed in KRs Dear Brian, I don't want to dampen anyones enthusiasm for building a nice airplane, however all builders of the KR-2 should be aware of the longitudinal stability problems with the aircraft. I should have been more specific in my earlier comment. Regarding slinging mud at the British and praising USA for it's experimental category, the United States of America's FAR Part 23.171 states that an aeroplane must be ".. longitudinally, directionally and laterally stable.. " and in addition ".. must show stability and control "feel" (static stability) in any condition encountered in service..". This regulation like all the FARs are based on experience. An aircraft built under the Experimental Category is exempt from the FARs to some extent, however anyone interested in flying safely would be well advised to heed the advice contained in these regulations. The British of course have a similar set of regulations, but no experimental category although they do allow KR-2s to fly there under a permit to fly. 23.175 spells out in more detail the requirements for stability across a range of speeds and configurations. There were also some excellent articles by the CAFE organisation in EAA's Sport Aviation on the stability characteristics of the Whitman Tailwind, the RV6 and a couple of other aircraft. The method of measuring stability is discussed in each case. So far I have not been able to convince CAFE to test the KR-2. Unfortunately no one has done a stability analysis (theoretical or flight test) of the KR-2 to my knowledge. Rand Robinson has been unable to supply one nor has any other builder. The problem is of course that very few people build a KR-2 according to plans. However the statistics speak for themselves in terms of the number of incidents with the KR-2. I recently received the following comment from the a head of a national branch of the EAA recently: ".. many people view the airplane (KR-2) as a toy and figure it will be a snap to fly. This as they find out to their dismay is not so. It will bite and fatally, as in many cases noted in the reports..". They also provided a reference to an article dealing with the design and building of this aircraft in Sport Aviation, January 1988 . There were over 600 KR-2s on the US register when I checked a few years ago. Not a bad score for something evolved from the model aircraft world (and Taylor Monoplane). However the extensive modifications to the Taylor Monoplane to make it a KR-2 will most likely have changed its flying characteristics dramatically. If the Taylor Monoplane was stable, it doesn't mean that the KR-2 is stable. Take a look at the tail volume of the KR-2 and compare it with almost any other aircraft and you will see the first source of low longitudinal stability of the KR-2. The really sad part of all this comment on stability is that some people are just plane (excuse the pun) reluctant to admit that there might be something basically wrong with the design of the aircraft that they have invested an enormous amount of time and money building. The low longitudinal stability problem can be fixed quite simply, however you have to be open to the idea that there might be a problem before you can appreciate the fix. It is a safety issue, not an ego issue. The KR-2 like any aircraft, can be flown in the unstable condition, it just isn't much fun and according to the statistics, plane dangerous. Bill Ginn ginnwj@ibm.net ------------------------------ Date: Tue, 24 Jun 1997 22:46:03 +1000 From: ginnwj Subject: KR: REMOVE Dennis Ambrose wrote: > > At 02:35 AM 6/23/97 -0400, you wrote: > > > >Kat: > > > >For your info and to share with your new computer geek guys... > > > >Subj: Only $799! P133 computer/16RAM/1.2GIG/6xCD > >Date: 97-06-22 07:36:19 EDT > >From: computer284@xqkq.netsales1.net (P133 Computer) > >Reply-to: computer3@netsales1.net > >To: computer284@xqkq.netsales1.net > > > > Only $799! P133 computer/16RAM/1.2GIG/6xCD > > > > Top quality peripherals and components are built into > > these high quality computers, such as USR, Toshiba, > > Mistumi, Samsung, Asus, etc. > > > > By ordering them over the internet, you can save a lot > > of money, and still get the absolute best quality. > > Go see for yourself at GreatDe > >als.Net. > > > > AMD K5-133 mhz desktop ... Only $799 > > > > computer (comparable to the Pentium) with Asus > > motherboard, 256k pipelined burst cache, 16 meg > > EDO RAM, Path Trio 64 bit 1 meg video card, 1.2 > > gig Samsung Hard Disk, 1.44 Mitsumi floppy drive, > > 6x Toshiba CD-ROM drive, 16 bit Creative Labs > > Soundblaster sound card, Mini Tower case, Mitsumi > > mouse, Mitsumi Windows 95 101 keyboard, Windows 95 > > CD installed, '97 Groliers Multimedia Encyclopedia, > > Netscape Navigator 3.0, Webtalk with microphone, > > and over 20 full software titles. One year warranty. > > Monitor is not included in this price, but we have > > a 14" analog for $179, 15" digital for $219, and > > 17" digital for only $399! > > > > Pentium 133/16RAM/2.1GIG/2meg video/33.6 voice USR modem > > ... only $999 Intel chipset > > > > Pentium 166/16RAM/2.1GIG/2meg video/33.6 USR voice modem > > ... only $1199 Intel chipset > > > > Pentium 200/32RAM/2.1GIG/2meg video/33.6 USR voice modem > > ... only $1499 Intel chipset > > > > Major OEM software titles, such as Lotus SmartSuite '97 for > > only $99 and many others, when you buy a computer. A variety > > of LabTech speakers also avaialble. > > > > There is a limited supply of these. So, first come, first > > serve. > > > > Order online at http://www.gre > >atdeals.net > > > > If you do not wish to receive any more notifications of > > great deals like this, just type REMOVE in the subject > > line and reply, and we'll take you off of our mailing list. > > > > > > > > ------------------------------ Date: Tue, 24 Jun 1997 06:49:25 -0700 From: enewbold@sprynet.com Subject: KR: A stable desing Out of curiosity, >I recently received the following comment from the a head of a national >branch of the EAA recently: >".. many people view the airplane (KR-2) as a toy and figure it will be >a snap to fly. This as they find out to their dismay is not so. It >will bite and fatally, as in many cases noted in the reports..". Just who might this "head of a national branch of the EAA" be? I have corresponded with both Tom and Paul Poberezny, and the only "national branch of the EAA" I am aware of IS the EAA at Oshkosh, WI. I, and every EAA member I've spoken with about the KR-2, have never for a moment considered the KR-2 to be a toy airplane or an enlarged R/C model. There have been a number of KR-2 incidents, but statistically speaking not anymore higher or lower than most other aircraft designs. >They also provided a reference to an article dealing with the design and >building of this aircraft in Sport Aviation, January 1988 . I'll get this issue out and check it out. >... Take a look at the tail volume of the KR-2 and >compare it with almost any other aircraft and you will see the first >source of low longitudinal stability of the KR-2. Sure. Compare it to the tail volume of the Zenith line of aircraft desings, and I think you'll be surprised. > ... It is a safety issue, not an ego issue. >The KR-2 like any aircraft, can be flown in the unstable condition, it >just isn't much fun and according to the statistics, plane dangerous. Well, Bill, I kinda have to disagree with you here. When properly constructed and balanced according to the plans as published, the KR-2 is just as stable and safe as any other design on the market today. Yes, the KR-2 can be built tail-heavy and become dangerous, but I wouldn't fault the general design of the aircraft because of someone violating the integrity of that design by poor & faulty craftsmanship. Ed Newbold Columbus, Ohio ------------------------------ Date: Tue, 24 Jun 1997 11:45:55 -0400 From: smithr Subject: KR: KR longitudinal stability Possibly like some of you, I made a decision to build a KR2S without really knowing what I was getting into and no pilots license. Fortunately, I began to read everything on the subject of homebuilts, flying and KRs. After completing the "boat", I decided it was mandatory to go to the KR fly in in Tennessee to continue my education. There I got my first flight in Troy's N100 when he let me try the stick under very turbulent high-speed conditions. Now here I am with no pilots licence and only about 15 hrs flying time trying to handle a KR. Not a chance. It was hopelessly out of control in the pitch axis. Fortunately Troy was a skilled pilot and well in control. I returned home thinking that maybe I should scrap the project. Instead, I decided that I would give it one more try with a KR at my home field - this time in calm air and at slow (120) speed (2 in the plane). (I also piled up more flying time in a 152) It turned out to be a much more pleasant experience. After ten minutes of getting used to it, I not only could maneuver it but was having fun. Landing was not made by me. As a beginner pilot I remained very concerned about the pitch sensitivity. I believe that the original KR2 was designed to be flown by an experienced pilot. I also believe that it might be possible to make a series of small changes to improve the pitch stability while still sticking close to the plans: 1) one change has already been made -the 2S has been stretched. 2) most important - keep the CG near forward limit (I am using only wing tanks to keep fuel from moving CG aft). 3) tail volume per plans may be marginal - I am increasing this slightly (4" span increase) and tapering to a 1" thick airfoil at the tip. 4) Stick force/throw may need improvement - I'm still considering this one but someone from KRnet suggested that a small change in elevator lever arm yields big success. I am hoping that the sum of small changes gives me a more forgiving plane. Comments are welcome. Disclaimer: These suggestions are made by a beginner pilot in hopes that the aero engineers will make and test the improvements necessary. Maybe beginners shouldn't fly KR's. Bob Smith, Albany, NY ------------------------------ Date: Tue, 24 Jun 1997 08:42:46 -0700 From: Micheal Mims Subject: KR: Formula V crash Did anyone catch the air race crash on the news? It looked like a formula V race. Two Soneris tried to occupy the same airspace at the same time. Pretty sad, we are not off to a good start this year as far as airshows go, three or four crashes already! If anyone on the ground gets hurt, airshows could very well be a thing of the past in the US considering the current philosophy of our elected officials! All it would take is one experimental aircraft to crash and kill spectators and we could lose more than airshows! ________________________________ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Micheal Mims Just Plane Nutts mailto:mimsmand@ix.netcom.com http://www.netcom.com/~mimsmand ------------------------------ Date: Tue, 24 Jun 1997 09:27:30 -0700 From: enewbold@sprynet.com Subject: KR: Re: KR longitudinal stability >I believe that the original KR2 was designed to be flown by an >experienced pilot. I also believe that it might be possible to >make a series of small changes to improve the pitch stability >while still sticking close to the plans: > 1) one change has already been made -the 2S has been stretched. Yep. Most of us will probably agree to this one! > 2) most important - keep the CG near forward limit An absolute necessity. Keeps the aircraft very stable. > 3) tail volume per plans may be marginal I dunno about this one. Seems to be OK to me and the rest of the guys in my EAA Chapter. > 4) Stick force/throw may need improvement Another good statement. A very good suggestion regarding desensitizing the elevator by reducing the movement of the control horn was in the last KR Newsletter; a good idea which I will incorporate into my aircraft. I was going to do it anyhow, I just think this particular idea was better than mine. >Maybe beginners shouldn't fly KR's. >Bob Smith, Albany, NY Nah, Bob. My suggestion is to keep accumulating flight experience while you're building, and then get someone qualified to test fly the little bird for you when it's ready. You should be all right by then. So, there are my opinions ... for what they're worth! Ed Newbold, Columbus, OH ------------------------------ Date: Tue, 24 Jun 1997 09:51:42 -0700 From: Micheal Mims Subject: Re: KR: KR longitudinal stability At 11:45 AM 6/24/97 -0400, you wrote: I believe that the original KR2 was designed to be flown by an experienced pilot. I also believe that it might be possible to make a series of small changes to improve the pitch stability while still sticking close to the plans: I have made the same changes to my KR2S, it will be interesting to see the results of the current fleet of KRs that are under construction, incorporating changes that should make it a whole new airplane! I think the control linkage ratio is an area that could help reduce the pilot induced oscillations. The elevator control is just simply too light! Here are some of the changes I have made to hopefully help sensitivity and stability: 1) Increase horizontal span 5 inches (2.5 each side) 2) Tapered horizontal to a 1 inch airfoil section rather than 1/2 inch sq. 3) Drilled cable attach holes one inch closer to center on elevator belcrank 4) Will only use 15 to 30% of airfoil for CG range 5) Considering adding strakes after more research on their effectiveness per square foot. (its not a 1 for 1 trade from what I understand) I have no "engineering background" and I am making these changes based on what I have read in articles written by Roncz and others with the "appropriate background". If anyone has a formula for determining the effectiveness of strakes, please pass it along. Maybe the variables for strakes are too wide for someone to nail down even basic data. I was looking at an aircraft that the Air Force is considering as a light piston trainer (to replace C-172s) and it had strakes about 20 inches long and with a 8 inch span. I guess the strakes may be something you just have to play with on each design? Anyway I plan to use them to make this bird fly like an arrow and I will pass the data along to future builders and or flyers who would like to install them on already flying KRs. But I guess you will have to wait another year! Maybe the 1998 gathering will be the dawn of the new KR! ________________________________ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Micheal Mims Just Plane Nutts mailto:mimsmand@ix.netcom.com http://www.netcom.com/~mimsmand ------------------------------ Date: Tue, 24 Jun 1997 10:09:14 -0700 From: Micheal Mims Subject: Re: KR: Re: KR longitudinal stability At 09:27 AM 6/24/97 -0700, you wrote: > 3) tail volume per plans may be marginal > >I dunno about this one. Seems to be OK to me and the rest of the >guys in my EAA Chapter. > Yes it is on the marginal side, according to worksheets for basic aircraft design it needs about 2 (KR2S) and 3 (KR2) more square feet of surface area. ________________________________ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Micheal Mims Just Plane Nutts mailto:mimsmand@ix.netcom.com http://www.netcom.com/~mimsmand ------------------------------ Date: Tue, 24 Jun 1997 10:17:48 -0700 From: David Moore Subject: Re: KR: Hinge Material Don, Not being a engineer myself this is something I had wondered about, aluminum vs. steel. Thank you very much for the information. Dave Moore At 01:42 PM 06/22/1997 -0700, you wrote: >David Moore wrote: >> >> I haven't done anything lately to stir-up the pot so here it goes, Do any >> of you areo-nautical engineer types tell me what the tensile strength of >> one of these aluminum hinges on the rudder and elevator would be if they >> are using a 3/16" bolt as a hinge? >> Now consider it is held on by two 3/16" bolts through a 5/8" wooden spar, >> with a doubler. Now of course the weakest part is probably the spar. >> > > > >I did a little calculating and have a few answers. > >The stabilizer will safely carry about 540 lbs with an ultimate load limit of 948 >lbs, using a standard semi-eliptic load distribution. This represents an FAR >part 23 yield load limit of slightly greater than 6 G's at 900 lb gross weight. > >Assuming the elevator hinges are made from 6061T6 and are 1 inch wide, 0.125 inch >thick, the hinge bolt is in the center of a 0.5 inch radius lug, and built to >acceptable standards of quality, then ONE lug will have the following failure >loads (Ultimate) > >Tension = 4265# (hinge lug tears apart) >Bearing = 2065# (material at the bolt deforms around the bolt) >bolt hole shear = 2742# (hinge bolt pulls through the hinge lug) > >If a 5/16" OD bushing is installed in the hinge lug, the failure loads (Ultimate) >become: > >Tension = 3609# >Bearing = 3438# >bolt hole shear = 2320# > >A 3/16" aircraft bolt will carry about 2070# in single shear. > >There are six hinge lugs, so multiple the individual failure load by 6 to get the >total failure load. There are three bolts, so multiply by three to get the total > failure load on the bolts. > >The yield load in about 2/3 of the ultimate load. This represents the upper >limit before a permanent change is seen in the material. > >There is also a cyclical failure mode caused by fatigue. This is similar to >bending a paperclip back forth until it breaks. In round numbers, if you keep >the working loads less than 10 percent of the yield load, then fatigue limits >won't be a problem. > >If you are still awake after all this, the hinges are a lot stronger than the >spars and I think the spars are strong enough. > >This is just a rough approximation of the stuff a designer has to go through. > >-- >Don Reid >(Somewhere in central Virginia) >donreid@erols.com > > David Moore Turnkey1@mscomm.com Hesperia, California ------------------------------ Date: Tue, 24 Jun 1997 14:44:31 -0400 From: smithr Subject: Re: KR: KR longitudinal stability Micheal Mims wrote: The elevator control is just simply too light! Here are some > of the changes I have made to hopefully help sensitivity and stability: > > 1) Increase horizontal span 5 inches (2.5 each side) > 2) Tapered horizontal to a 1 inch airfoil section rather than 1/2 inch sq. > 3) Drilled cable attach holes one inch closer to center on elevator belcrank > 4) Will only use 15 to 30% of airfoil for CG range > 5) Considering adding strakes after more research on their effectiveness per > square foot. (its not a 1 for 1 trade from what I understand) > On above point #3: This sounds good for increasing stick force (desirable) but in physics you don't get something for nothing. It will also yield more degrees of elevator deflection per inch of stick movement. This might not be good if you are trying to reduce pitchiness. The KR needs both more stick force and (slightly) more stick movement per deg of elevator deflection. I don't know what will give both. Possibly a non-linear cam. Bob Smith, Albany, NY ------------------------------ Date: Tue, 24 Jun 1997 14:57:14 -0700 From: "David M. Gargasz" Subject: Re: KR: Hinge Material Donald Reid wrote: > > David Moore wrote: > > > > I haven't done anything lately to stir-up the pot so here it goes, Do any > > of you areo-nautical engineer types tell me what the tensile strength of > > one of these aluminum hinges on the rudder and elevator would be if they > > are using a 3/16" bolt as a hinge? > > Now consider it is held on by two 3/16" bolts through a 5/8" wooden spar, > > with a doubler. Now of course the weakest part is probably the spar. > > > > > I did a little calculating and have a few answers. > > The stabilizer will safely carry about 540 lbs with an ultimate load limit of 948 > lbs, using a standard semi-eliptic load distribution. This represents an FAR > part 23 yield load limit of slightly greater than 6 G's at 900 lb gross weight. > > Assuming the elevator hinges are made from 6061T6 and are 1 inch wide, 0.125 inch > thick, the hinge bolt is in the center of a 0.5 inch radius lug, and built to > acceptable standards of quality, then ONE lug will have the following failure > loads (Ultimate) > > Tension = 4265# (hinge lug tears apart) > Bearing = 2065# (material at the bolt deforms around the bolt) > bolt hole shear = 2742# (hinge bolt pulls through the hinge lug) > > If a 5/16" OD bushing is installed in the hinge lug, the failure loads (Ultimate) > become: > > Tension = 3609# > Bearing = 3438# > bolt hole shear = 2320# > > A 3/16" aircraft bolt will carry about 2070# in single shear. > > There are six hinge lugs, so multiple the individual failure load by 6 to get the > total failure load. There are three bolts, so multiply by three to get the total > failure load on the bolts. > > The yield load in about 2/3 of the ultimate load. This represents the upper > limit before a permanent change is seen in the material. > > There is also a cyclical failure mode caused by fatigue. This is similar to > bending a paperclip back forth until it breaks. In round numbers, if you keep > the working loads less than 10 percent of the yield load, then fatigue limits > won't be a problem. > > If you are still awake after all this, the hinges are a lot stronger than the > spars and I think the spars are strong enough. > > This is just a rough approximation of the stuff a designer has to go through. > > -- > Don Reid > (Somewhere in central Virginia) > donreid@erols.com Hi Don, With a eye ball conclusion with all this informatio it occured to me 3/16"x 1 3/4" AN42B-17 steel eye bolts min tensile strength 125,000 psi [3]@ each with a drilled locked clevis pins for a hinge, with steel back plates where attached to the dbl 5/8" wood, should do a better job without any added wieght than the alum. chanel arangement. Any alignment problems could be solved with washers, the inspection covers would be smaller. Thank you for your well thought opinion. Gene Gargasz Elyria Ohio ------------------------------ End of krnet-l-digest V1 #48 ****************************