KR> Useful Load
Kayak Chris wrote: > Can i assume that no one has used the formula to determine stall > speed? Not sure how to with the RAF48, no idea what the Coefficiant of > Lift is, although the "new" airfoil probably has it someplace, or what > to input with the density of air number. Anyone care to take a stab at > it with the KR1 or 2? See the diagram next to the bottom of http://www.n56ml.com/kraf48.html for the max lift coefficient, which is the Eppler code diagram, and was done fairly recently, calculated from the coordinates of the RAF48. I don't claim to be an aerodynamicist, but I would choose use the solid Re (Reynolds number) line (1x106) curve to be conservative (based on 50 mph stall at 15 degrees AOA, standard air density, and 42" average wing chord (anal extraction). This gives a ~Re of 1.7M or so (and the solid plotted line represents 1.0M). I'd work the details and give all my assumptions, but as soon as I do, some real aero engineer will pick it apart to make me look stupid, so I'll let him make the assumptions and provide results, and take the glory. I did this calc 20 years ago, and the units were the PITA, but using an online converter, it makes it easy. If nobody's done it by this weekend, I'll do it again. I haven't volunteered because I've (almost) learned to quit volunteering to do stuff that other people can do...I couldn't get everything done that I plan to do before I die, even if I lived another 50 years! [I'm getting selfish with my time]. The table at the very bottom of the page is for the RAF40, which is something like 1.33 at 16 degree AOA "un-flapped", which is what almost all of the KRs are. And the KRs that have flaps are not full span, for sure. It's provided as it probably came from real wind tunnel data, but was likely generated in the 1930's or 40's, although the thinner chord would likely have a little less lift anyway. Density of air is "standard air density", which you are probably familiar with, standard pressure and temperature. Either find a density that's in the proper units, or put conversion factors in the equation. I'm supposed to be working right now... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Mechanical Belly Board
Joe Nunley wrote: > Does anyone have a working mechanical Belly board? See the 2004 MVN Gathering photos, about 22 pictures down to see Bill Clapp's VW emergency brake speed brake lever. It's at http://www.krnet.org/mvn2004/ . Rand Robinson used to sell an aluminum version that was a lot lighter, shorter, and less robust... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> wing tank building material - vinyl ester
If you get nothing else out of this thread, it should be that you shouldn't build fuel tanks out of epoxy, now that we have vinyl ester. Yes, you can slosh the tank and probably get good results, but it's another step, and you have to do it right. But if you use vinyl ester resin (Aircraft Spruce sells it) you're not likely to ever have a problem with it. Keep in mind that once promoted (and that's how AS sells it), the shelf life will only be 2-3 months, so this is not something you want to order in advance. And it will stink up your house for days or weeks, so try to do this outside. And don't do it in high temperatures, as the cure time is reduced to minutes. Catalyzing small quantities is measured in a very few drops, so one drop too many and you might have five minutes of working time, and that's hard to accomplish anything that involves wetting out fabric. On the other hand, I built my last wing tank in my hangar at over 100F, and I finished it in a day! That's another reason industry likes this stuff...productivity! Oh, and wear safety glasses when adding catalyst. One drop of the MEKP catalyst will blind you within minutes, if not seconds... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com to KRnet-leave at list.krnet.org
KR> Tire Pressures
Bob Sauer wrote: > What tire pressure is being used for the mains and the nose wheel? My Plane > is 700 lbs. and has the suggested rims and tires. I fill mine up to 50 psi, mainly to keep from pinching tubes on hard landings. I check them every 2-3 months and top them off again, but it's not a problem to keep less in it. What I have learned though is below about 25 psi, the chances of pinching a tube (and creating a leak) go way up below 25 psi. And early warning is when I roll the plane out of the hangar and the tires squeak...they are usually low. Of course 50 psi means more bounce on landings, so there is a tradeoff. And depending on your tube, it may not even handle 50 psi (my Cheng Shins are good to 70 psi). If you are fanatical about maintaining tire pressure, 40 psi may be a better number. I don't have a nose wheel, but I would expect it to be similar. I'm sure there are other opinions, but that's been my experience... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Broke Brake
Joe Nunley wrote: > I have Cleveland wheels and calipers with Suzuki GSXR 750 brake cylinders. > The brake cylinders are a custom heal brake configuration mounted > horizontally. Are the brake cylinders fed fluid by a remote reservoir that's mounted higher than the cylinders, or are the reservoirs built into the cylinders? If there's no reservoir mounted higher and filled with fluid, air bubbles in the cylinders are a real possibility. My experience has been that bleeding the brakes is best done with a simple mechanical oil pump, think oil squirting gun with a plastic tube on the end, or even a pressurized garden sprayer, filling from the brake bleeder and up through the rest of the system. This way, air bubbles are carried up (their natural direction), and if there's a leak somewhere it becomes apparent. If pulling a vacuum from the top of the system, if you have a leak it will suck in air bubbles, and it will not be obvious if it's a small leak. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Attach Wood firewall to frame
Jim Ellison wrote: > If you put a full 1/2 inch pice of 9 ply wood and then. The aluminum 3 inch > angle. Behind it. With the 5 attach points engine mount. From great planes. > What does the neters think about this compination ?? No beefing up of the firewall area is required. In fact, the 3x3 angle is not even needed if the engine mount is properly designed to connect at the corners, rather than out near the middle like the original design. See the photo at the bottom of http://www.n56ml.com/kfuse.html for what I mean by that. I tore a gear leg off the plane and bent the engine mount (with a 250 pound Corvair hanging off of it), and my 1/4" "per plans" firewall is still firmly attached... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> KR Poll, last chance ENOUGH!!!!!!
As Paul requested from the beginning, please respond to his request OFF-NET! That means, "DON'T SEND YOUR REPLY TO 800 PEOPLE! He also said "put the letter in the subject area". That would make it easy on him to sort and count them. But n, why make it easy on the guy And I KNOW this is asking way too much of people that are apparently smart enough to be building airplanes, but the list rules also ask that you delete the vast majority of the previous post before replying, which would mean (in this case) ALL of it, because the SUBJECT tells the whole story. But that would assume you'd actually READ the post before you replied to 800 people! I can't believe how incredibly dense some folks are. It's a very simple concept, and so rarely complied with Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Oilite bushing insertion
Stefan Balatchev wrote: > I am considering using Oilite bushings for my tail movable surfaces. Press > fit seems out of the reach for me, so I would try the following method, > please let me know if somebody else tried that and if yes, what was the > outcome...< I just drilled a hole, maybe reamed it to size (I forget) and used Loctite 620 between bushing and aluminum. If it was a press fit, I probably just tapped it in place. With 1130 hours on the plane, there is no noticeable play in the rudder hinges. If you want to do as you plan, you can drill the hole in advance. The hole will grow with the rest of the part. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> KR2S gross weight question
Folks who witnessed the attempted destruction of a stub spar at a past Gathering will probably agree that the spars have a significant margin of safety on the KRs. The spars were jacked up to the point of being bent probably 14" upward from the fuselage, and neither fuselage nor spars gave. Finally, the shear web started to split, but the spars were still fine and ready to accept more load. Anybody who witnesses that test had to walk away impressed with the spar strength, especially considering that in anything like normal (but bumpy) flight, the wings never even flex. And despite all the concern about the WAFs and their connection, neither wing component is likely to fail, and in fact, never have in any kind of normal (not crash) flight. Larry Flesner and I have seen wings where the spar broke on impact with the ground at the bottom of a spin, and the spar broke a few inches from the WAF, not at the WAF or the connections from WAF to spars. Marty Roberts used to fly big guys at the Gathering hard and fast, with a gross weight of probably 1200+ pounds, and his g-meter would usually come back with 6g's or so stuck on it. He reset it for every flight. Just a data point, but I personally will lose no sleep over my spars breaking... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> KR2S gross weight question
Gary Wold wrote: > I've been researching this for a little while but am not finding any real > info. What are KR2S builders using as their gross weight? I'm looking at > tri-gear and Corvair engine. I would think the average is probably between 1100 and 1200 on the data plate. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> LED Strobe lights
Stefan Balatchev wrote: >>I found there are few LED flash strobes available from different sources, any >>of you having experience with that? Are these LED strobes accepted by the FAA >>for experimental aircraft?<< There are some fairly specific rules regarding navigation lights, but not so many with strobes. Jim Weir recently started a series of Kitplanes articles on how to make your own LED nav and strobe lights, and one of the things he said about the strobe regulations are that they are vague enough to drive a truck through. I've never seen an FAA guy with a lumen meter either. But one hard and fast rule is that you have to be able to see them just about all the way around, so one strobe on top may not get you there, although that would be a pretty close second. Don't take my word for it though...seek out the regulations and check. And if the plane is already built and you add them to an experimental, the builder can add them and be night legal with a logbook entry. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Fwd: Re: RST Engineering
Looks like we all need a break for a few days, so any mail sent to the list will go into a "moderated" black hole for a few days, so don't bother sending email to the list. I'm tired of this... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com .org to change options
KR> IFly 740
Larry H wrote: > ...$899.00 includes a new series 740 which claims easy seeing in bright > sunlight and a stratus kit which displays all surrounding aircraft that are > in the system I presume.< That's likely a "StratuX kit", as the Stratus ADS-b is not a kit, and is proprietary to Foreflight, and won't work with the iFly. I flew up to OSH with a borrowed Stratux, but it shut down every few minutes due to overheating, I think. So if you build a Stratux kit, be advised to choose a housing with a fan in it to keep the computer cool! I will likely build one shortly...it's a great value for the money. I also brought along another borrowed Stratus, and it worked perfectly and continuously with Foreflight on my iPhone. I had to leave the kitchen sink at home though... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Cylinder Heads Again
Roger Bulla wrote: > Has anyone tried these heads from CB Performance? They look like they have > better air flow around the exhaust ports and maybe better quality control?< Looks like maybe they have swapped to the "Chinese castings", which are improved over the CB 044 heads that came on N891JF. These are essentially what I bought from DRD Racing. I've done a lot of photos of these and several other choices over the last few weeks, having replaced my heads a week or so ago. See http://www.n56ml.com/n891jf/vw/ for more on this. It's a comparison of several different heads and their air passages. I was happy with the quality of the DRD heads, which looked very similar to the ones in your link. I've put two hours on them so far, and the thing still runs hot, so I'm on a baffling witch hunt now. I need some "conformal" fiberglass plenums on that thing like I have on the Corvair. I'm still looking for ideas on "what works" in various VW aircraft installations, because what I have isn't working. I took off in 95 degree temp yesterday, and after idling to the runway and a quick runup, it was at 400F as I turned crosswind, and I wasn't even at pattern altitude yet! Baffling is pretty tight on this thing, but what I don't know is what's going on in flight between the top of the cowling and the fiberglass/silicone seal. That's my main mission for the next three days until I take off for OSH. One more thing I'm going to do is wrap those hot exhaust pipes (just inside the inlet) with insulating wrap. No sense in preheating my inlet air... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Back-up profile engine mount
Stef wrote: > To install the engine mount on the firewall I have to install according > drawing > a L shaped .125 thickness. On the drawing I cant find the length of this L > profile. Do I install it over the full length of the upper shelf? I left out the angle entirely. I don't think you need it (and I've proven it) if you attach the engine mount near the longerons...where the load path is. Just a small pad of 1/8" aluminum epoxied to the wood on the backside to prevent pull through should be fine. Save weight wherever possible... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Can't post to kr net
Mike Arnold wrote: > I can't seem to post a thread and pictures to the kr net anyone know why?? Because you are trying to post 13MB of photos, with a list limit of 220KB, 50 times larger than what's allowed. You need to resize and compress the photos if you want to post them. See http://www.krnet.org/info.html for the list rules, which explain this... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Airventure "Building and "Flying the KR Aircraft" presentation, July 25th, 11:30 AM
Reminder, There will be an AirVenture presentation on the first day of the show. If nothing else, it will be a question and answer period, and a way for KR builders and pilots to meet and greet. Afterwards, we'll walk out to the vicinity of Homebuilt Headquarters (where we've parked for the last few years) for a show and tell for those interested. Details are below: Building and Flying the KR Aircraft Monday, July 25 - Monday, July 25 11:30 AM - 12:45 PM Location: Forum Stage 3 Presenter: Mark Langford http://www.eaa.org/airventure/event/Building_and_Flying_the_KR_Aircraft?id=FBC31A4683644B24828C0319247CCB78 Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Florida
I would be up for a BBQ trip to Green Cove Springs for a KR get-together to as well, weather permitting. Last time I was there I knocked over a runway light while turning around. I'll try to be more careful this time. Gorgeous place, and lots of personalities there... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Let's make KRnet useful again
OK, enough of Windows. We could all write a book on it. Please end it here. Does anybody have anything to contribute regarding KRs, KR engines, the KR Gathering, or methods of KR construction? At one time we used to share useful information regarding how to build things. How about coming up with a post on how to do something. It can be simple stuff, like how to accurately locate and drill a hole, scarf a joint (that's not a drug term), achieve a nice finish on your airplane, remove the plastic from your Plexiglas canopy...remember this kind of stuff? People have questions, people have answers. Everybody go off in a corner and either come up with a question you need answers to, opinions on how to do something, or a How-To article on something you're an expert on. Let's get back to basics... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> painting update.
Mike Sylvester wrote: >> Hey guys, I should have said sanding update as I have been basically taking >> off most all of the 2 part epoxy primer. Six days of hellish 12 hour days >> but the sanding is over with. Gonna try my hand at painting tomorrow. I'll >> let you know how it comes out. Let me say that I will never build another >> composite airplane, An all metal Sonex is looking good about now.<< Yep, high build primer is designed to sand, but 2 part epoxy is intended to go on and stay there, sanding or not! You'll appreciate that composite airplane when you leave the Sonexes in the dust. This exercise in futility will seem insignificant when you fly it to the Gathering the first time. We're proud of ya! Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Axles?
Tommy Waymack wrote: > May need to upgrade to 3/4"axles and bearings. GPASC can help I second this motion. When I bought 891JF the wheels were splayed out several degrees in both camber and toe-out. I'm not sure what kind of steel those 5/8" axles were made of, but they were quite soft and easily bent, and not up to the job of landing a 1000 pound plane, apparently. Fortunately those went away when I went to Matcos, which use the 1.25" aluminum axles that are virtually bulletproof (tested to 5.5 g's, at least). Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Elevator control cables.
And keep in mind that there should be an adjustable turnbuckle in each of those two cables, set to a neutral position, for adjustment in stick location and to get the cable tension right. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> VW cylinder heads
There's a photo comparison of the "Chinese" heads at http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=2EW3tGIDH3wRUhpa0YWijyN56D=13=707, as well as a link to the HOT VWs pages with more comparisons. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> VW cylinder heads
To add to the insightful post that Owen Hughes (SVD) wrote yesterday day on VWs, I would avoid the Mofoco heads. The photos show lots of fins, and that's great, but what they are lacking is cooling air passages, I mean almost nothing. If the air's not flowing through the fins, they're going to run hot. I'm looking into this same subject lately, now that it's gotten hot and I fly in the 90's most of the time, and I'm tired of seeing 400F when I'm only 500' off the runway on the first flight of the day. I ran across a photo over the weekend from a Dec 2010 Hot VWs article that showed bottom views of 18 heads they reviewed, and Fomoco's weren't so great. On the other hand, the "Chinese" heads were awesome, lots of daylight between the fins, and by most accounts I've found, the quality is very high, and the price quite reasonable. DRD Aircooled sells them, and I plan to order some tonight. Whatever you buy, make sure you get stainless valves! Another good chart that wraps up a lot of VW head details is at http://www.thesamba.com/vw/forum/viewtopic.php?t=573099 Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Ifly 720
Brian Kraut wrote: > Ifly 720. I powered it up over the weekend and noticed that it > took probably a minute or so to boot up and operation seems to not be > very fast on it. I kind of expected that on their dedicated hardware > that it would zip right along or at least run as good as it does on my > phone that is also running 100 other processes at the same time. I also > noticed that the touch screen requires a harder touch than my phone or > tablet Right on all counts! Mine probably takes well over two minutes to boot, and the touch screen isn't as sensitive as in iPhone, which may be by design. And the absence of an on/off switch is unforgiveable, as is the absence of at least a tiny battery to get you through cycling other power on or off for a few seconds. The other biggie is the super glossy screen. It just doesn't work well in a plane with a canopy. I had to buy another touch screen for mine for $120 after relatively little usage, but the previous one had a non-glare sheet over it. I may have even bought the non-glare thing...I forget, but I'm looking for another one now. Other than these nits, it's a great unit, but the conclusion I've drawn is to run it on an iPad, which can be bought used for under $100, and you get the best of both worlds. iPad hardware is pretty dang reliable and trouble free. I'm using my daughter discarded after many years of hard use, and everything on works like the day it was new. And what a battery... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> MGL and the new instrument panel
Steve Bedford wrote: > This is a iefis g3 firmware upgrade from mgl?s website. I believe it was > ported to the g2 iefis what is probably what you have. Thanks Steve, but mine's a G3 and I upgraded it to the new G3 firmware shortly after it was released in December, with high hopes, and could tell no discernible difference. I was amazed that it was recently discovered that this processor was used in cell phones. I believe the phrase "suppressing radio RX noise from EFIS in compromised installations" is designed to imply "improper installation", but I've proven, with nothing more than the unit and a battery and an o-scope, that the only thing compromised about my installation is having that EFIS in the panel... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Removable Front Deck
A removable front deck is a necessity, in my mind, and it's so easy to do during initial construction, there's no reason not to do it (unless the half a pound of flox and hinges is prohibitively heavy...and it ain't!). I show one way to do it at http://www.n56ml.com/kmlfd.html and I did the same for the aft deck at http://www.n56ml.com/kad.html. Risky? Both have been tested for 1130 hours, and at 245mph top speed, if that'll work for you. Oh, and with a 245 pound Corvair engine hanging off the firewall. Imagine trying to access your brake cylinders. First step is to climb into the KR and lay down across the seat. Impossible? Yes, so you'll have to lay across the seat with your butt up on the longeron and feet dangling over the wing, while you finagle your shoulder through the 6" slot formed between the panel and main spar. But your shoulder is all that fits...your body prevents you from reaching any further. Now reach way out with your hand, and you STILL can't reach the pedals or the cylinders, much less get TWO arms in there to remove any bolts. So whatever you do, have to be one handed, which doesn't work, since you can't reach anything anyway. Next step, remove the instrument panel! You did make all of your electrical connections "connectorized", right? No? Then start disconnecting the battery and all of your switches! Oh, panel won't come out because of throttle, mixture, carb heat connections? Disconnect those from the engine and pull them loose so the panel will come out. You can quickly see that a removable front deck is simply a necessity, not a convenience. And after all that invasive surgery to your vital controls and electrical connections, you may have compromised flight safety in the process, just to access a brake cylinder. One of my POS brake cylinders leaks down after holding my foot on the brake for more than about five seconds, and then I have no brakes on the left side. I'd love to fix it so my brakes don't go away while landing, but I simply can't get there! And bleeding brakes is not uncommon (leaks so happen), so unless you have a remote reservoir on the firewall, how do you refill them? With a removable front deck (or at least a large access panel), modifying or troubleshooting the instrument panel is a breeze. If you can't get these critical items, you're going to let things slide and further compromise flight safety. Just my 2 cents worth, based on experience with a KR2 that was built to the plans...no removable deck, and a fuel tank between the panel and the firewall (bad idea!). I could go on, trust me, but I'm short on time, since I really need to get out to the airport and tear my instrument panel out to replace an IEFIS system that is simply not up to the job. For more opinions regarding KR building, see http://www.n56ml.com/kopinion.html ... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Type 1 Cylinder Heads - cooling
Phil Hill wrote: > I don't know, I think a smart person might consider becoming a North > American distributor... I've been watching these guys from Motorav at OSH and SNF for the last few years, and I think the only "flyer" that I brought home from SNF last year was from Motorav. I thought to myself..."these guys are doing it right!". They have some very interesting ignition ideas too. My next plane will be Corvair powered though. 50% more power, 50% more weight, but lot more reliability in the form of two extra cylinders for safety, valves that never need adjusting, better engine cooling, lower head temperatures, better engine cooling, and very rare valve issues. A quality 4340 crankshaft costs twice as much as the VW crank, but it puts an end to the biggest Corvair risk, using a reground crankshaft. And the Corvair fifth bearing options are much simpler and less troublesome than the VW front bearing experience that I've had (that deserves a webpage all by itself!). If carrying an extra 80 pounds of engine around, it's worth it in the ability to get off the runway and get altitude in a hurry, even if one cylinder is dead. And just because you have 50% more power doesn't mean you burn 50% more fuel, just throttle back to the same speed as the VW and you will get very similar fuel burn, although there is a slight penalty (~7%, depending on all-up aircraft weight)for the extra weight. Yep...that's another web page coming... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Oil additives
Speaking of oil, the CorvAircraft community has been using Rotella 15W-40 oil for years now, given that it has one of the highest zinc contents. Also, we add something called ZDDP MAXX to our oil at oil change time. Look for ZDDP MAXX on ebay. ZDDP is the active ingredient that matters...MAXX is just brandname. ZDDP is the stuff that most oils had in abundance until catalytic converters and other changes lowered it considerably in most oils. Adding ZDDP back into your oil is helpful, especially on a rebuilt engine, as it provides better lubrication between a new camshaft and lifters, preventing spalling, for example. I use it on the VW also. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Facet_fuel_pump_flare?
I think I just verified it. See the photo at http://www.n56ml.com/fuel/05121531m.jpg , which shows the 37 degree Earl's fittings, and the number 40108 written in Sharpie on the top of the pump. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Facet fuel pump flare?
Pete Klapp wrote: > Mark Your fuel system page shows your Facet fuel pumps connected to fuel > lines using AN fittings. I spoke with a "tech?" at Facet and he "thought they > were a 45 deg SAE flare" as they only made fuel pumps for automotive use. Had > you had any leaks or problems using the 37 deg AN fittings? Did you alter the > AN fittings to 45 deg?< I'm pretty sure they are 37 degree fittings. I think the part number is shown on the diagram at http://www.n56ml.com/fuel/index.html , 40108. You probably got this from the chart at http://www.facet-purolator.com/cube-fuel-pumps.php , where the picture doesn't match the pump...it shows NPT female threads, and the description only says "3/8 flare", but it's 37 degrees for sure. He's probably thinking SAE brake lines. If I go to the airport today I will verify it... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Canopy Choices
I reread it... > 2. The original canopy looks like it would cause excess drag due to the > abrupt angle change where it meets the forward deck. The back side is more important than the front side. The nicely rounded surface guides the air around fine... the trailing edge being faired in gently is the important thing. I flew back from St. Louis Sunday trying to stretch my fuel, and was burning 2.9 gph at 130 mph TAS (which is independent of winds, although I did have a 25 mph HEAD wind). This is 45 mpg, which ain't half bad. Going up I did about 147 burning 3.5 gph, or 42 mph. I flew up at 10,500' and back at 9500'. I like to keep a long glide path under me... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Canopy Choices
Matt Quimby wrote: > 1. Has anyone used the Aircraft Spruce KR2 canopy, and do you have pictures? > What about other options? > 2. The original canopy looks like it would cause excess drag due to the > abrupt angle change where it meets the forward deck. Is this a valid reason > to choose a different canopy, or is the performance difference probably too > small to notice?< If you see a canopy with a discontinuity in the flow lines to the aft deck, it's because the canopy wasn't installed correctly to start with, although the bubble doesn't necessarily make it easy. N891JF has the stock canopy, and it's quite well faired into the aft deck (see http://www.n56ml.com/n891jf/ for photos). Jim Hill used a Dragonfly canopy on his stock width KR2 and it fit fine, if that's a concern. It was kind of neat...it turned in just a bit on the sides, so he had great visibility forward and out to the side as well...his head wasn't confined to the fishbowl that you get with a bubble canopy. Looking at it now, he must have cut at least 18" off the back though, which I would have left there for even better visibility. See Jim Hill's canopy at http://www.n56ml.com/jhill.html. The Todds canopy is a blown canopy, so it's a bit on the bulbous side, but the price is certainly right. Steve Glover at nvAero does sell the Dragonfly canopy. I used a Dragonfly on my first plane, and that's what I'll use on my next plane, if it's a two seater. That's at http://www.n56ml.com/kcf.html. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> KR Engine Cowling
Phil Matheson wrote: > What is your web address Roger? I don't think it's really Roger's address, just a recommendation on a good source and supply. It's at http://shop.fiberglasssupply.com/Carbon_and_Kevlar_Fabric-Carbon_6oz_x_50_Plain_Weave.html?utm_source=Carbon+Fiber+Sale_campaign=Carbon+Sale_medium=email Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> weight and balance
Chris Prata wrote: >If 35% aft from the leading edge (at mean average chord point) is too far aft, >what is the commonly accepted safe limit and where in your experience does she >fly best? There's some ambiguity there, as the plans call for 8"-16" from the leading edge of the stub wing, and the range is quoted as 15%-35%, and 20% of 48" is 7.6", so the numbers don't jive. But let's say take 2" off of the 16" for simplicity and call it 8" to 14" for an "amended" CG range, then check the max forward loaded condition (lightest pilot and full/empty fuel, depending on where your tanks are). Then calculate worst case with heavy passengers and aft-most fuel situation and make sure you're nowhere near the aft end of the range, adjusting as necessary to get that range situated toward the middle, or biased toward the front. Generally speaking the further aft the CG is, the less stable it will be. There are few downsides to a forward CG, being able to lift the nosewheeel for rotation being one, and having to crank in some nose up trim (extra drag being the other. The downside to too far aft is that the plane is a handful to fly, or, it kills you shortly after takeoff! N56ML is slightly forward in the condition that I usually fly it in, with half fuel, me as pilot, and the usual 20 lbs of crap I carry (tools, spare radio, camera, etc) sitting on the seat. I've put some pretty heavy people in there and it gets a little light on the stick, but not dangerous, and most people that've flown my plane would call it quite reasonable. N891JF was set up by Jim Faughn to be right on the forward end of the range with full fuel and him as pilot. Needless to say, on my first flight, I took off with neutral trim and flew it up to cruise altitude that way. Then I started checking control reactions and when I let go of the stick it immediately nose dived! That's the downside...it needs trim cranked in. That won't kill you though. I have since added a few things aft (flap, backup battery, APRS, ELT), so it's a little more aft, and I noticed yesterday that my previous landing after a long cruise back home, the trim tab was level with the elevator, so I'm flying it "typically" with no up or down trim now, and it's quite fine...but the heaviest person I've carried is my 100 pound daughter! See http://www.n56ml.com/wb/index.html for more on what happens if you go too far aft. Been there, done that, and don't want to repeat it! Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> C.G location, Engine centerline
Pete Klapp wrote: >What about changing the location of the cg range, or should I stay with RR >location? If I remember correctly, the Diehl skin instructions don't call out a change in CG location over the KR2 plans, even though the wing planform changes a bit (just taper and length, I think). Same with the KR2S...still 8"-16" aft of the stub wing leading edge. I didn't answer your question the first time because I couldn't figure out what you meant by "With those, the leading edge of the wing is 11.5" fwd of the front spar face, and 1.5" fwd of RR plans". The plans simply say "CG range is 15%-35% of wing chord, 8"-16" aft of the inboard leading edge." Yes...I know that math doesn't quite work out. But I would just stick with that, given no other information to the contrary, with the exception that I'd call it 8"-14" for reasons we all know...the aft 2" is not a pleasant place, if not just plane unstable. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Carbon Fiber speed brake
Just shoot me. I have to figure out how to make "plain text" the default on this goofy web interface, if it's possible. See below... I should add to this that given that you are putting holes in it, plywood core does make perfect sense, and I would laminate it all together and then cut the holes. That's a lot easier than the other way, and it'll work fine. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Carbon Fiber speed brake
KR> Carbon Fiber speed brake
Let me try that again...this time as "plain text" so it won't post a blank. Paul Visk wrote: >>I made my with 3/32 birch. I followed Mark Langford's design... Not quite...mine was made from 1/4" Lastofoam, rather than plywood. I'll bet it's even stiffer than an eighth inch plywood base, as the distance between the two carbon fiber sides gives it a very high moment of inertia. I'm sure everybody's seen it already, but http://www.n56ml.com/n891jf/speedbrake/ shows exactly how mine was made. I've deployed it up to 120 mph with no problems, so it is tested and makes a huge difference in slowing the airplane down, as well as improving the view over the nose. If I forget to retract it after landing, I have to give it a lot more power to taxi fast! Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Carbon Fiber speed brake
KR> fuel tank glassing
Gary Shubert wrote: >What is the consensus on sloshing compounds? >I am building with foam and Vinyl Ester. I think you can't go wrong with vinyl ester, without sloshing compound. I've run over 5000 gallons of auto fuel through N56ML over a 6 year period, and well over 1000 gallons with ethanol in it...no problems. This is the stuff that AS sells, Derakane. I wouldn't put sloshing compound on top of that. Some have no problems with sloshing, some do have problems. If it's not there, it can't come loose and clog up the outlet. If you look hard enough, there are versions of Derakane that are even more fuel resistant, but only sold by the 55 gallon drum, best I can tell. For those who haven't seen it, for how I built my tanks, see http://www.n56ml.com/900hour/ (a long-range tank for the Airventure Cup race) http://www.n56ml.com/kft.html (I never used this one, went to wing tanks instead) http://www.n56ml.com/swings.html (my main wing tanks) Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Wing Attach Fittings
Mac wrote: >>I had this discussion with our PFA engineers in UK, and they told me that any unwanted blank holes in the spar should be plugged with a bolt shank. The theory being that a wooden dowel could compress and weaken the spar.<< Steel bolts in the holes pretty much precludes redrilling the spar cap to make the WAFs fit properly, so that's not an option on this application. It's a moot point anyway for curing the single hole alignment problem between the two WAFs. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Wing Attach Fittings (et-al)
KR> Aileron spar
Paul Visk wrote: >>The point I was trying to make was. What's wrong with using wood screws on >>the aileron hinges? Just curious. I think it has been proven that they work >>on belly boards going 130 mph and they don't fall off. One think I can think >>of. The plans call for Nut plates and getting it past the DAR might be an >>issue. Being the ailerons are a primary flight control and the speed brake is >>not.<< I think you answered your own question...primary flight controls. Also, the flap installation has the screws primarily in shear, but the ailerons are also in tension, although the loads are far less...unless you flutter them! And screws in wood and in tension can be pulled through. That's a lot more difficult with nuts or nutplates on the other side. You knew that already though. Indeed, "primary flight controls" is the reason you don't want to leave anything to chance. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> wing weight
Gary H wrote: Does anyone have an idea how much an outboard 5048 wing might weigh? (Primed, not painted, with or no wing tanks.) The AS5048 wing will only be slightly (maybe a max of 5%) heavier than an RAF48 wing, mostly due to the thicker cross section caused by the 18% thick airfoil as opposed to the 15% thick RAF48. For the longer KR2S wing, that's probably 50-55 pounds each, depending on how much "icing" and primer is on the thing, and how hard you tried to keep it light... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> weight engine fairings
Stef wrote: "I am bussy to calculate the weight of the engine before I can design the engine mount. What is the everage weight of the hood or the fairings or covers around the engine. I did a small calculation and think it should be around 6 lb." I would be surprised if the "baffling" most people use weighs more than three pounds, with two being closer to average. I know my fiberglass plenums are probably about a pound for both. My entire cowling weighs only four pounds (without paint), but it's carbon fiber and designed to be very light. By contrast, the cowling on N891JF weighs 14 pounds, made quite stout from fiberglass, with insulation built in around the exhaust (it's very tightly cowled). Baffling on N891JF weighs around two pounds, I would guess, but will weigh it next time I'm at the airport. It's thin aluminum with thin baffling silicone around the edges. The VW is far more difficult to keep air-tight than the Corvair, which has two simple surfaces to bolt a plenum onto. For those who don't know what I mean about the plenums, see http://www.n56ml.com/corvair/plenum/. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com Original Message Subject: KR> weight engine fairings From: stefkr2--- via KRnet List-Post: krnet@list.krnet.org Date: Mon, September 28, 2015 3:12 am To: Kr net Kr net Cc: "stefkr2 at kpnmail.nl" KR friends, I am bussy to calculate the weight of the engine before I can design the engine mount. What is the everage weight of the hood or the fairings or covers around the engine. I did a small calculation and think it should be around 6 lb. What do you all think or what is the weight of yours. Thanks Stef -- Steph and his dad are building the KR-2S see http://www.masttotaalconcept.nl/kr2 ___ Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org please see other KRnet info at http://www.krnet.org/info.html see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options
KR> 2015 Gathering "winners"
Jeff Scott wrote: "You guys that hung out at home or flew commercial and left your KRs sitting in the hangar are really missing out on some great experiences. " I'm with you brother. You know (although some may not) my excuse...a connecting rod stuck through the top of my VW engine case. I was really looking forward to the trip...more like five "regular" trips spread over two days, but it'll have to wait until the next "out-west" Gathering. I did a little figuring a few months ago, and the fuel cost alone was going to be around $1500, which is about double what the airline ticket cost me a month in advance. I'd always thought of airliners as aluminum tube time machines, but "sewer pipes with wings" comes a lot closer! I worked on the Gathering photos some last night (something like 800 of them), and it's going to take some time to sift through them for the good ones and title them all. It's not a trivial effort, but I hope to knock it out this weekend. I will answer the question of "who won what" though. Jeff Scott won Best Firewall Forward and Greatest Distance Flown, as well as the coveted People's Choice award, while Kim Neibauer won Best Paint, Best Interior and Panel, and Best Judged. Kim's plane is newly minted, so he definitely had an advantage, and kudos for him for flying out from Colorado with so few hours under his belt. Roger Bulla's plane was a close third in many respects, but maybe next time. I do applaud Dan and John for running a great Gathering, and I welcomed the change of venue. As for N891JF, I've ordered just about everything it's going to take to "rebuild" it, although it will essentially be an entirely new engine, except the sheet metal that goes under the cylinders... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Double shear WAFs
Let me try that again...this time as plain text rather than "rich text"... John Bouyea wrote: >>Don Reid wrote back in 2007 that the WAF bolts function better as a single bolt in double shear top & bottom (2 total) than 2 on each fitting, forward and aft, top & bottom (4 total).<< I think most folks realized that a single bolt would be better than one, but the implementation is slightly challenging. I originally just went with two single shear bolts...because it was clearly working fine for the hundreds of KRs built before mine, and still had a lot of airplane left to build at the time! But later, my incentive was to make the wings easier to get off and on after I closed up the gaps between the inner and outer stub wings. So while I had the wings off to build another wing tank, I went single shear as well. As you can see by the nut plates holding the bolts in place, this arrangement isn't far from a "pinned joint". It's shown at http://www.n56ml.com/900hour/, as well as how to build a vinyl ester fuel tank in a matter of hours, and "after-the-fact" Hoerner wing tips. Don Reid also did an article in the August 1995 KR Newsletter regarding the specific WAF design...the value of the "lightning" holes in load sharing. The Newsletters are posted at http://www.krnet.org/newsletter/ . I'll try to identify exactly which batch that one is in and post it tonight. Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> Double shear WAFs
KR> Foam
KR> "new" airfoil sweep
Jon Kimmel wrote: >>Unfortunately the reduction in sweep changes the location of the mac. I did the calculations a few months ago...and I can't decipher my post it notes...but the change moves the usable check range forward about a half inch. << These airfoil templates were drawn up at a time when many of us had spars built and in place, but were questioning the RAF48 when better airfoils existed. We were fortunate to have an airfoil expert design an airfoil especially for the KR2S for us. And a "selling point", from the safety point of view (and to short-circuit the naysayers), was to use the existing spars. It may not have been the perfect solution, but lengthening the horizontal stab and using a more effective airfoil for the tail surfaces improved even more on the longer KR2S. If you'd like to draw up another set of templates, along with a new spar design to match it, I'll happily add them to the "new airfoil" site as a fourth alternative for "new construction". In the meantime, those of us who've built wings per the original templates and put hundreds of hours on them will probably stick with what we have... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
KR> KR2s engine mount for Corvair??
Stan wrote: >>Still waiting on my plans from Aero I ordered in February so I thought id ask the group if they had dimensions for an engine mount to fit a 110HP corvair engine in a KR2S?<< See http://www.n56ml.com/corvair/mount_fit.html for a pretty good idea... Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
