krnet-l-digest Sunday, May 4 1997 Volume 01 : Number 008 ---------------------------------------------------------------------- Date: Sun, 4 May 97 05:00:00 UT From: "Craig Sellers" Subject: RE: KR:Prop came off >I will ask the ignorant question. How do you know if it is hardened? The easiest way is to see if the washer is dish shaped after the prop hub has been properly torqued. If it is deflected then the washer is definitely not airworthy. You can remove the washer after torquing the Hub down once and the washer should still be perfectly flat - if not it is no good. Also, If the cotter pin hole on your bolt ends up too far into the crankshaft then watch out - you most likely have a bad washer. The harder way is to have it tested on a Rockwell Hardness Tester, as we did after the failure. It should definitely have a reading greater than HRC 35 if it is a hardened washer. If the hardness test is below this value then I would not use that washer. Both of the washers we had exceeded the Proportional Limit (as described below) after they were torqued to the recommended specs and then run on the engines for less than 30 minutes. This causes the washers to be permanently deformed into a concave (dished) shape. "When you apply a load to a material, there is a stress in the material proportional to the load and area and measured in force/unit area (ie Pounds per square inch or psi). This stress will cause the material to deflect by an amount known as the strain which would be measured in units of length (inches). The maximum stress at which a material fails is called its Ultimate Strength. Long before the load gets to that point, the material will reach what is known as it's Proportional Limit. This is the point on the stress/strain curve where the material will begin to deform plastically as opposed to elastically (ie. It won't return to it's original shape once the load is removed). As an example, for hot rolled, low carbon steel, the ultimated stress in tension is 65,000 psi and the yield stress is 36,000 psi." Craig Sellers N34SS ------------------------------ Date: Sat, 03 May 1997 22:17:50 -0700 From: Ross Youngblood Subject: Re: KR:Prop came off Craig Sellers wrote: > > Last week we were testing a KR2-S with type IV engine. When doing a static > engine runup the prop hub came off along with the propellor. Fortunately the > plane was on the ground and no one was hit by the splintered pieces of the > prop when it hit the ground. The hub was a Great Plains Force 1 hub. It > appears that the washer which holds the hub on was not hardened - it became > dish shaped - this caused the retaining bolt to become loose, the cotter pin > then sheared, the bolt holding the hub on became unscrewed and the hub and > prop came off the engine. We also had another type IV that was built up at > the same time and found that it also had a hub retaining washer that was also > not hardened. I also have one of these hubs also on my KR-2. It appears that > mine is hardened as I have flown it over 500 hours with no problem and the > washer does not appear to be "dished". I recall seeing something about this > somewhere, but it is VERY VERY important that anyone using a Great Plains > force 1 hub make sure that you have a hardened washer holding the hub on. > This would obviously be a very bad thing to happen in flight. If someone > knows when and how many of the bad washers were shipped please let us know. > I personally now know of at least two of them. These hubs were purchased > about 3 years ago. > > Craig Sellers KR2 N34SS Anyone who could post tips on how to check an unused washer for hardness is encouraged to post. I have the standard taper hub, not the FORCE-1 hub, and think I also have a washer behind the retaining bolt, should I inspect this? Or run the engine a bit then check it. -- Ross ------------------------------ Date: Sat, 03 May 1997 22:32:06 -0700 From: Ross Youngblood Subject: KR: VW Carb placement Well, I gave a quick hangar tour tonight after our EAA meeting and one of our members is a seasoned A&P. When he saw my hangar mates "AERO VEE" and the downtube intake manifold setup he went into a wonderfully opinionated discussion of how thats how it was done in the 20's and the carb should be re-located to the TOP of the engine. Somthing to the order of "Just because we've been doing it wrong for 50 years doesn't make it right". I have read (possibly here on KRNET) that this will give 15-20% more (RPM? or was it HP?) at any rate, a noticable improvement. So... I'm thinking I'd have to move some tubing, and re-fab my cowling etc so it's not somthing I'm going to do THIS year, but it seems there is yet another informed opinion that placing the carb on top is probably a good idea. When asked "why" this makes such an improvement, the response was that the fuel has to flow "up" against gravity. This sounds reasonable. Other issues such as fuel leaking onto the engine or exhaust manifold were discussed, with an Ellison (which is what I'm using), he indicated that the pressure cowl would blow any fuel out away from the exhaust manifold. And heat shields could be used on the exhaust as well. Just thought I'd throw it out... it seemed like a good alternative, but not for me as I want to fly what I've got so far first. -- Regards Ross ------------------------------ Date: Sat, 03 May 1997 22:55:58 -0700 From: Ross Youngblood Subject: KR: Fuel System Question I have two wing tanks each with a filter & electric pump which are individually switched at this time. These are currently slated to a L-R-OFF fuel selector switch which could either: A) Pump pressurized fuel directly to the carb. or B) Pump fuel into the 5 gal header tank, which would then be gravity fed. or C) Fuel System Drawing #70 page 83 of May '86 plans. This has a "T" fitting installed to feed both the header tank and the top of the sight gauge. ??? Option A might violate the KISS principle and I'm concerned about a wing tank becoming unported in a bank if it is a primary fuel source. (I don't think flop tubes will help this) I do have the baffels installed per plans. (May 86 rev Page 82 Photo#42). Option B should require a float to detect the fuel level in the header tank, which I was hoping to avoid (complexity). Also, Gravity Feed seems to provide questionable reliability on climb out, but was my idea for reserve fuel. I have plumbed 3/8" tubing downstream of the fuel selector to keep this option open, however my Ellison EFS-2 is shipped with a 1/4" AN fitting, so for now, I have ordered a AEROQUIP hose from the EFS-2 to the gascolator. This may change after fuel flow tests. Option C... go with the plans? I'm concerned that the "T" fitting being placed in line with the sight gauge will give me false readings with the pump on, and does not guarentee pressurized fuel to the Ellison, as the header tank is vented. Also fuel could get pumped out of the vent. I think there was an old newsletter article about this... I will be looking for it in my back issues. So can any experienced KR fliers post regarding their fuel system routings? I am intrested in both gravity feed systems with header tank only, and wing tank systems. I will be reviewing the newsletters for this information too, but any posts would be helpfull! Ross Youngblood ------------------------------ Date: Sat, 03 May 1997 23:04:05 -0700 From: Ross Youngblood Subject: KR: VW Carb Placement correction >Other issues such as fuel leaking onto the engine or exhaust manifold >were discussed, with an Ellison (which is what I'm using), he indicated >that the pressure cowl would blow any fuel out away from the exhaust >manifold. And heat shields could be used on the exhaust as well. Actually this wasn't quite clear, it seems that float carbs are more likely to leak fuel than the Ellison, but thats just what I got from the discussion. My post seemed to read that the Ellison would leak, this is not the case at least not that I know of. Also he mentioned that the downtube hoses would be "nothing but trouble". I'm keeping my downtube hoses for now, but I liked getting an outsiders opinion and thought I would share it with the KR Netters for some good horse beating this week. -- Ross ------------------------------ Date: Sun, 4 May 1997 00:18:35 -0600 (MDT) From: Ron Lee Subject: Re: KR: VW Carb placement (selective snipping) >the 20's and the carb should be re-located to the TOP of the engine. >Somthing to the order of "Just because we've been doing it wrong for >50 years doesn't make it right". > > I have read (possibly here on KRNET) that this will give 15-20% more >(RPM? or was it HP?) at any rate, a noticable improvement. So... > > When asked "why" this makes such an improvement, the response was >that the fuel has to flow "up" against gravity. This sounds reasonable. >Other issues such as fuel leaking onto the engine or exhaust manifold >were discussed, with an Ellison (which is what I'm using), he indicated >that the pressure cowl would blow any fuel out away from the exhaust >manifold. And heat shields could be used on the exhaust as well. > > Ross This post in combo with the one on gasoline plumbing may be interrelated. If you put the carb on top, would that rule out gravity feed as as option? In that case, the plumbing would run from the bottom of the header to a carb that might be higher. Also, it took me a few minutes to figure out the unporting in a bank from the previous post. if the left tank is nearly empty, and you bank to the left, an inboard tube might become exposed to air (no gasoline). Ron ------------------------------ Date: Sat, 03 May 1997 23:48:47 -0700 From: Ross Youngblood Subject: Re: KR: VW Carb placement Ron Lee wrote: > > (selective snipping) > > This post in combo with the one on gasoline plumbing may be interrelated. > If you put the carb on top, would that rule out gravity feed as as option? I think so.. not too much drop for gravity to help out, need high wings for that. > Also, it took me a few minutes to figure out the unporting in a bank from > the previous post. if the left tank is nearly empty, and you bank to the > left, an inboard tube might become exposed to air (no gasoline).Yes that's what I am pondering... Looking at Murphy's Law, and wanting Murphy to stay on the ground when I'm flying. Ross Youngblood ------------------------------ Date: Sun, 4 May 1997 05:55:36 -0400 (EDT) From: Tom Crawford Subject: Re: KR: VW Carb placement On Sat, 3 May 1997, Ross Youngblood wrote: > Well, I gave a quick hangar tour tonight after our EAA meeting and one > of our members is a seasoned A&P. When he saw my hangar mates > "AERO VEE" and the downtube intake manifold setup he went into a > wonderfully opinionated discussion of how thats how it was done in > the 20's and the carb should be re-located to the TOP of the engine. > Somthing to the order of "Just because we've been doing it wrong for > 50 years doesn't make it right". > > I have read (possibly here on KRNET) that this will give 15-20% more > (RPM? or was it HP?) at any rate, a noticable improvement. So... > I'm thinking I'd have to move some tubing, and re-fab my cowling etc > so it's not somthing I'm going to do THIS year, but it seems there > is yet another informed opinion that placing the carb on top is probably > a good idea. > > When asked "why" this makes such an improvement, the response was > that the fuel has to flow "up" against gravity. This sounds reasonable. > Other issues such as fuel leaking onto the engine or exhaust manifold > were discussed, with an Ellison (which is what I'm using), he indicated > that the pressure cowl would blow any fuel out away from the exhaust > manifold. And heat shields could be used on the exhaust as well. > > Just thought I'd throw it out... it seemed like a good alternative, > but not for me as I want to fly what I've got so far first. > > -- Regards > Ross Ross, This is the carb system that I am putting together now. Ellison carb mounted on top of the engine. Ben Ellison strongly recommends that you top mount on VW engines. There are a couple of "bugs" to work out though. 1) As someone mentioned, with the carb up that high, you probably wont get gravity flow from a partially full header tank. I will be using the stock header tank with the gascolator in the standard position- bottom of the left side of the firewall, with 2 electric fuel pumps. (Belt AND Suspenders) 2) With the carb on top, there is not much room for a carb heat box with ram air. Your options are limited. I have made a box that I am working with now. I'll keep you posted. Tom Crawford KR4QV Gainesville, FL tomc@afn.org KR2 N262TC 90% done, 50% to go. ------------------------------ Date: Sun, 4 May 1997 09:12:20 -0400 (EDT) From: Baleco@aol.com Subject: Re: KR: KR-1 motor glider. In a message dated 97-05-03 13:32:35 EDT, you write: << They all said " you can't just take a single place maching and add a second seat (longer fuse) and add some wing area- you need to start over from scratch and the ship will cost three times what a single place ship would to construct and will have mediocre performance" >> Gee wiz Dave, I just can't get away from you. Besides building a Fisher Horizon 2 I too am a member of the Sailplane Homebuilders Association. I'm gonna be building a pair of Woodstocks with another EAA chapter member. I too would much prefer to build a two place. Dave is correct guys, you are not gonna stretch the fuse and add some wing on this one. If it was that easy the Woodstock, Marske's Pioneer and the others would be offered as two place sailplanes. Heck there's still not much choice in two place certified sailplanes. Marty Hammersmith Sonerai pilot Horizon 2 & Woodstock builder Hummelbird & GP-4 dreamer ------------------------------ Date: Sun, 4 May 1997 09:31:05 -0400 From: "Curt Martin" Subject: KR: Re: VW Carb placement > I have read (possibly here on KRNET) that this will give 15-20% more > (RPM? or was it HP?) at any rate, a noticable improvement. So... > I'm thinking I'd have to move some tubing, and re-fab my cowling etc > so it's not somthing I'm going to do THIS year, but it seems there > is yet another informed opinion that placing the carb on top is probably > a good idea. If I may make an observation from the automotive world... Long intake runners tend to produce peak torque and horsepower at a lower RPM's Short intake runners produce more horsepower, less torque, but at a higher RPM. In other words.. two otherwise identical motors (displacement, cam, and heads), would produce completely different power and torque curves based on different runner lengths alone. An example of this would be the Chevrolet Tuned Port Injection manifold (very long runners) vs. the Chevrolet LT-1 manifold (short runners). The TPI is known to be a torque monster, but runs out of breath at 4500 rpm. Same motor fitted with an LT-1 manifold produces less torque, more horsepower, but at a higher RPM. Since an aircraft needs to swing a prop, a higher torque, lower RPM motor would be better than a low torque, high RPM motor, correct? We are restricted to a maximum RPM for direct drive based on the diameter of the prop and that somewhat inconvenient speed of sound. We also are stuck with one gear per flight (the pitch of the propeller) So mounting the carbs on top with short runners will produce a higher peak Horsepower, but might also move the RPM at which that Horsepower is attained past the limit we can spin the propeller. If I were to do this, I'd find the optimum runner length, then bend and twist it to find the best physical location to fit under the cowling. As far as pulling gas uphill... well, a vacuum cleaner work regardless of whether the hose is pointing up or down. So mounting the carb under or over would have no effect on the ability to suck a fuel/air charge into the motor. We only care about the atomized fuel (on which the effects of gravity are more than cancelled by the vacuum of the engine.) Any liquid fuel in the intake runners is a hindrance, so if it runs back downhill towards the carb, or drips into the cylinders, who cares? As long as it finds a way out of the system someplace. Now, does anyone have the cam specs for various VW aircraft conversions... I noticed that these were strangely absent from the Great Plains catalog. They dedicate a lot of info to Bore, Stroke, Compression numbers, etc. but leave out the cam specs? I'd love to run some of the numbers through a few PC-dyno simulations to see what HP/RPM and Torque/RPM curves get produced. > -- Regards > Ross Curt Martin (cmartin@america.com) Ormond Beach, FL http://www.america.com/~cmartin ------------------------------ Date: Sun, 04 May 1997 09:09:59 -0700 From: Donald Reid Subject: Re: KR: Fuel System Question Ross Youngblood wrote: > > I have two wing tanks each with a filter & electric pump which are > individually switched at this time. These are currently slated > to a L-R-OFF fuel selector switch which could either: > > A) Pump pressurized fuel directly to the carb. > or > B) Pump fuel into the 5 gal header tank, which would then > be gravity fed. > or > C) Fuel System Drawing #70 page 83 of May '86 plans. This > has a "T" fitting installed to feed both the header tank > and the top of the sight gauge. > > ??? > BIG SNIP I am not flying yet, so I will tell you what I am doing and the reasons for it. a) I agree with your concern about Option A. b) My favorite. In mine, I am using an overflow line back to the tanks. My plan is to draw from both wing tanks simultaneously, and then overflow to a common return plumbed to both tanks. I like the Cessna way of both tanks in service and reduced fuel management hassles. My header tank has two float switches (AS&S P/N 6905-400) that will be on separate circuits. One is the low (3 gallons) and the other is lo-lo( 2.5 gallons). Panel lights will be green for pump running, yellow at low, and red - land right now. Preflight test by either draining sufficient fuel and then refilling or raising the tail to drain fuel through the return line, then slowly lowering the tail back to where it belongs (on the ground) and watching the lights go out. If the tanks don't feed evenly, I have isolation valves and will go back to the tank swapping routine, including swapping the overflow to the correct tank. The other option is to use the level switches as on-off controls for the pump. If you go this way, there are more fittings and tubing to install. The other thing to remember is that the gravity return will require a larger return line than than the supply line. A Facet pump will put out as much as 30gph; gravity return is much slower. I did a calculation using conservative assumptions and 1/2" should work, which means I used 5/8". c) In Tony Bingelis's books, he says not to tie into the sight gage line. I know from personal experience that flow into and near a standpipe level indicator can drastically change the indication. d) A possible option is to have a slightly larger header tank and manually transfer 3-5 gallons at a time. This is probably the simplest solution. Don "Just another aero wiz kid" Reid donreid@erols.com ------------------------------ Date: Sun, 4 May 1997 10:07:38 -0400 (EDT) From: Baleco@aol.com Subject: Re: KR: VW Carb placement In a message dated 97-05-04 01:31:24 EDT, you write: << Other issues such as fuel leaking onto the engine or exhaust manifold were discussed, with an Ellison (which is what I'm using), he indicated that the pressure cowl would blow any fuel out away from the exhaust manifold. And heat shields could be used on the exhaust as well. >> I thought about moving the Ellison on top in the Sonerai. I'd have to add a fuel pump since the gravity feed backup would be gone and then contend with all the stuff about leaks, heat shields etc. That second pump will need additional plumbing and a seperate electrical source too. It's getting a little heavy and complicated don't you think? I'm facing the same question on my Subaru/Ellison for the Horizon 2. It may go on top because this aircraft will already have dual electrical sources since I'm gonna run a single distributor ignition unless someone comes up with a magneto for an EA-81. There'd again be concerns for fuel leaks, the need for heat shields etc. Hummmn, I sure didn't provide any solid answers did I? Oh, I've been running the Ellison for over two years now. I've never seen any fuel drip out of it. Marty Hammersmith ------------------------------ Date: Sun, 4 May 1997 12:31:55 -0400 (EDT) From: JEHayward@aol.com Subject: KR: Horiz stab One other question before I get started on the stab.... is it better/easier to install the spars THEN install the foam or install the foam/spars as an assembly? ------------------------------ Date: Sun, 04 May 1997 09:52:51 -0700 From: Peter Hudson Subject: Re: KR: Is the turtledeck structural? Hi guys, I feel the need to interject some thoughts here. During the last few weeks it has been said that the ribs, fiberglass, and turtledeck are "not structural". We can't forget that the fiberglass wing skins ARE structural because the provide the required torsional stiffness to the wings. They also transfer the lift to the spars. The ribs are structural in that they are required to stabilize the skin so it can do it's jobs and so your airfoil stays roughly the same shape under loads. The turtle deck is structural in that it provides torsional stiffness to the fuselage. These parts are lightly loaded and may not carry primary bending loads which are the biggies but we still need to use some caution when modifying them. If the turtledeck is made removable, be sure that it can provide the torsional stiffness when attached. if the wing skins are not per plan, make sure they are STIFF enough to limit the torsion on the wing in flight and strong enough to handle taking the lift loads to the spars. Keep the ribs two inches thick and don't put -big- holes in them. Well I've said my piece...these things do perform some structural tasks even if just to stabilize the "primary" structure so take the "non-structural" statements as "secondary structure" and you'll be alright. - -Peter- > > The turtledeck,indeed the whole top everything is not structural, so > >you could make it removeable, some people have done that. > > > > Robert Covington > > Gee, since the weight is already there, it seems that someone would > have made it structural... > Vince Bozik - Athens, Georgia ------------------------------ Date: Sun, 04 May 1997 09:59:48 -0700 From: Ross Youngblood Subject: Re: KR: Re: VW Carb placement Curt Martin wrote: > > If I may make an observation from the automotive world... > > Long intake runners tend to produce peak torque and horsepower at a lower RPM's > Short intake runners produce more horsepower, less torque, but at a higher RPM. Ahhh... I love this stuff. Plus the vacuum cleaner idea too. Curt, Thanks for the post. > Now, does anyone have the cam specs for various VW aircraft conversions... I > noticed that these were strangely absent from the Great Plains catalog. They > dedicate a lot of info to Bore, Stroke, Compression numbers, etc. but leave out > the cam specs? > I'd love to run some of the numbers through a few PC-dyno simulations to see > what HP/RPM and Torque/RPM curves get produced. > Curt Martin (cmartin@america.com) > Ormond Beach, FL > http://www.america.com/~cmartin Curt, I have a sheet that shipped with my GPASC cam. It is a SCAT HI Performance CAM Installation & Break-in instruction sheet. It lists several CAM grinds C-20,C-25,C-35,C-45,C-55,C-65,C-75 and C-95. Grind Lift Duration INT OPN INT CLS EXH OPN EXH CLS C-20 .338" 278 31BT 67AB 67BB 31AT C-25 .385" 275 30BT 65AB 65BB 30AT C-35 .410" 286 34BT 70AB 70BB 34AT C-45 .418" 296 39BT 75AB 75BB 47AT C-55 .428" 312 47BT 83AB 88BB 48AT C-65 .440" 318 48BT 88AB 88BB 64AT C-75 .445" 342 64BT 96AB 96BB 64AT C-95 .475" 286 34BT 70AB 70BB 34AT I have double checked these entries, but they may have typos in them. The C-20 grind is circled on this piece of paper, I think that I did this, but don't recall how I came up with that selection. I also seem to recall that the C-65 grind was popular with Rex Talor of HAPI engines (now Mosler), can anyone confirm that? I always ASSUMED that a cam for TORQUE would be the best choice where most Cams advertised in HOT VW's are for HIGH RPM operation. I want good LOW end... which also supports long intake tube runners (perhaps). -- Ross ------------------------------ Date: Sun, 04 May 1997 10:03:42 -0700 From: Ross Youngblood Subject: Re: KR: Fuel System Question Donald Reid wrote: Thanks for the overflow line idea. That would be easy to plumb. Also I agree that tieing into the sight gauge line is a BAD idea. I will check on the floats. Keep me posted. Ross Youngblood ------------------------------ Date: Sun, 04 May 1997 10:07:04 -0700 From: Ross Youngblood Subject: Re: KR: Horiz stab JEHayward@aol.com wrote: > > One other question before I get started on the stab.... is it > better/easier to install the spars THEN install the foam or install the > foam/spars as an assembly? I did the stabilizer off the plane but AFTER aligining the hinges with a 3/16" rod, and checking this out on the fuselage. It was pretty easy to install the stabilizer after that, in fact the additional weight will probably make the job easier, the spars will have a tendancy to stay put while you make your water level checks. -- Ross ------------------------------ Date: Sun, 04 May 1997 10:14:23 -0700 From: Ross Youngblood Subject: KR: Parts for sale. I reached Clyde Lloyd who was selling his KR for $9K. I was going to take some picutres. It turns out that a mesquite[sp?] bush jumped out from nowhere and pushed the runway out from under the plane. ... (I'm taking poetic license), actually he had just lifted the tail up and a gust of wind came up. Soo... there is a change. Instead of $9K, he is selling the engine (1835cc), new mag, Zenith carb, instruments and a trailer for $3500. Contact: Clyde LLoyd Roseburg OR graphicd@users.wizzards.net (541) -- I posted the phone number earlier.. this would be the best way to reach Clyde... I'm looking for it but have to run.. my daughter is bugging me to go to the pet store and buy a rabbit... I promised! She reminds me. Here he was minding his own business, when a gust of wind come Ross Youngblood ------------------------------ Date: Sun, 04 May 1997 10:18:07 -0700 From: Peter Hudson Subject: KR: feather-fill and progress Hi guys, First a little progress report. My port outer wing panel is ready for finish. Wow... a real airplane part in the garage. After a lot of micro and sanding, I brushed on a coat of epoxy primer. It looks like there is still a lot more sanding and filling to go. I'm going to try a patch of micro over the primer in an out of the way place to see if I can still use it for filling the spots I thought I'd already finished. I guess I also need someone to "hold my hand" cause feather fill scares me. the long-ez plans say use it first, then primer, then paint. The rule of thumb says epoxy over polyester is okay but not polyester over epoxy. The epoxy primer I used (Ditzler DT90 carbon black etc.) says to let cure for XX days before using body fillers (I assume feather fill fits in there). I brushed on the first coat of primer because that really fills the pin holes well and it will give me a color warning before I sand through fibers while sanding and feather-filling. I'm worried about the feather fill shrinkage with time and the feather-fill bond to epoxy (primer or structural). Any comments on these things before I make a mess? ------------------------------ Date: Sun, 04 May 1997 10:24:10 -0700 From: Peter Hudson Subject: KR: Weight of outer panel Hi again, I almost forgot to metion in my feather-fill post. I weighed my outer panel. With micro, without primer,filler,or paint. With Strobe power supply (1.6 lbs) and wiring (.5 lbs?) with aileron, balance lead, and hinge it weighs 36 lbs. I'll let you know how much after filling and painting (I've seen 40 lbs here a few times so it looks like I'm doing OK.) - -Peter- ------------------------------ Date: Sun, 04 May 1997 10:21:27 -0700 From: Micheal Mims Subject: Re: KR: VW Carb Placement correction At 11:04 PM 5/3/97 -0700, you wrote: >Actually this wasn't quite clear, it seems that float carbs are more >likely to leak fuel than the Ellison, but thats just what I got from >the discussion. My post seemed to read that the Ellison would leak, >this is not the case at least not that I know of. > Ellisons do dump a little fuel on shutdown. _______________________ ~~~~~~~~~~~~~~~~~~~~~~ Micheal Mims Just Plane Nutts mailto:mimsmand@ix.netcom.com http://www.netcom.com/~mimsmand ------------------------------ Date: Sun, 04 May 1997 10:20:00 -0700 From: Micheal Mims Subject: Re: KR: Fuel System Question At 10:55 PM 5/3/97 -0700, you wrote: Option A might violate the KISS principle and I'm concerned about >a wing tank becoming unported in a bank if it is a primary fuel source. >(I don't think flop tubes will help this) I do have the baffels installed per >plans. (May 86 rev Page 82 Photo#42). > > If you keep your slip skid ball centered in turns your fuel outlet should not become unported! Micheal Mims ------------------------------ Date: Sun, 04 May 1997 10:28:08 -0700 From: Micheal Mims Subject: Re: KR: Horiz stab At 12:31 PM 5/4/97 -0400, you wrote: > One other question before I get started on the stab.... is it >better/easier to install the spars THEN install the foam or install the >foam/spars as an assembly? > I installed the spars and then foamed, I think you will be better off foaming and sanding before you mount them. Its kind hard to shape the bottom foam because the fuselage is in the way! I did it, but I cursed a lot in the process!! Micheal Mims ------------------------------ Date: Mon, 5 May 1997 02:54:58 -0700 From: "Gary Lee" Subject: Re: KR: Fuel System Question This system of fuel management has already been designed and has worked perfectly for over 50 years. It was installed in the 6000 Ercoupes that were made from the 40s to 70s? Fuel was pumped continuously from the wing tanks to the header with an overflow back to either tank ( some were on the right and some were on the left tank ). There is an .041 restriction on the pump outlet, so the fuel entering the fuselage tank will not overwhelm the overflow. Sizes were good for up to 90 or 100hp fuel consumption rates. Find a local Ercoupe and just measure the supply and return lines. Gary cptlee@castles.com - ---------- > From: Donald Reid > To: krnet-l@teleport.com > Subject: Re: KR: Fuel System Question > Date: Sunday, May 04, 1997 9:09 AM > > Ross Youngblood wrote: > > > > I have two wing tanks each with a filter & electric pump which are > > individually switched at this time. These are currently slated > > to a L-R-OFF fuel selector switch which could either: > > > > A) Pump pressurized fuel directly to the carb. > > or > > B) Pump fuel into the 5 gal header tank, which would then > > be gravity fed. > > or > > C) Fuel System Drawing #70 page 83 of May '86 plans. This > > has a "T" fitting installed to feed both the header tank > > and the top of the sight gauge. > > > > ??? > > BIG SNIP > > I am not flying yet, so I will tell you what I am doing and the reasons > for it. > > a) I agree with your concern about Option A. > > b) My favorite. In mine, I am using an overflow line back to the tanks. > My plan is to draw from both wing tanks simultaneously, and then > overflow to a common return plumbed to both tanks. I like the Cessna way > of both tanks in service and reduced fuel management hassles. My header > tank has two float switches (AS&S P/N 6905-400) that will be on separate > circuits. One is the low (3 gallons) and the other is lo-lo( 2.5 > gallons). Panel lights will be green for pump running, yellow at low, > and red - land right now. > > Preflight test by either draining sufficient fuel and then refilling or > raising the tail to drain fuel through the return line, then slowly > lowering the tail back to where it belongs (on the ground) and watching > the lights go out. If the tanks don't feed evenly, I have isolation > valves and will go back to the tank swapping routine, including swapping > the overflow to the correct tank. The other option is to use the level > switches as on-off controls for the pump. > > If you go this way, there are more fittings and tubing to install. The > other thing to remember is that the gravity return will require a larger > return line than than the supply line. A Facet pump will put out as much > as 30gph; gravity return is much slower. I did a calculation using > conservative assumptions and 1/2" should work, which means I used 5/8". > > c) In Tony Bingelis's books, he says not to tie into the sight gage line. > I know from personal experience that flow into and near a standpipe > level indicator can drastically change the indication. > > d) A possible option is to have a slightly larger header tank and > manually transfer 3-5 gallons at a time. This is probably the simplest > solution. > > Don "Just another aero wiz kid" Reid > donreid@erols.com ------------------------------ Date: Sun, 04 May 1997 14:41:15 -0500 From: Paul Eberhardt Subject: Re: KR:Prop came off I will ask the ignorant question. How do you know if it is hardened? Another way of checking hardness is to try to file it. Hardened (grade 8) material is almost as hard as the file and will only scratch slightly while non-hardened material files easily. Paul Eberhardt > The easiest way is to see if the washer is dish shaped after the prop hub has > been properly torqued. If it is deflected then the washer is definitely not > airworthy. You can remove the washer after torquing the Hub down once and the > washer should still be perfectly flat - if not it is no good. Also, If the > cotter pin hole on your bolt ends up too far into the crankshaft then watch > out - you most likely have a bad washer. > > The harder way is to have it tested on a Rockwell Hardness Tester, as we did > after the failure. It should definitely have a reading greater than HRC 35 if > it is a hardened washer. If the hardness test is below this value then I > would not use that washer. > > Both of the washers we had exceeded the Proportional Limit (as described > below) after they were torqued to the recommended specs and then run on the > engines for less than 30 minutes. This causes the washers to be permanently > deformed into a concave (dished) shape. > > "When you apply a load to a material, there is a stress in the material > proportional to the load and area and measured in force/unit area (ie > Pounds per square inch or psi). This stress will cause the material > to deflect by an amount known as the strain which would be measured in > units of length (inches). The maximum stress at which a material > fails is called its Ultimate Strength. Long before the load gets to > that point, the material will reach what is known as it's > Proportional Limit. This is the point on the stress/strain curve > where the material will begin to deform plastically as opposed to > elastically (ie. It won't return to it's original shape once the load > is removed). As an example, for hot rolled, low carbon steel, the > ultimated stress in tension is 65,000 psi and the yield stress is > 36,000 psi." > > Craig Sellers N34SS ------------------------------ Date: Sun, 4 May 1997 14:50:32 -0700 From: R Covington Subject: Re: KR: Is the turtledeck structural? >Hi guys, > >I feel the need to interject some thoughts here. During the last few >weeks it has been said that the ribs, fiberglass, and turtledeck are >"not structural". > We can't forget that the fiberglass wing skins ARE structural because >the provide the required torsional stiffness to the wings. They also >transfer the lift to the spars. > The ribs are structural in that they are required to stabilize the >skin so it can do it's jobs and so your airfoil stays roughly the same >shape under loads. > The turtle deck is structural in that it provides torsional stiffness >to the fuselage. > >These parts are lightly loaded and may not carry primary bending loads >which are the biggies but we still need to use some caution when >modifying them. If the turtledeck is made removable, be sure that it >can provide the torsional stiffness when attached. if the wing skins >are not per plan, make sure they are STIFF enough to limit the torsion >on the wing in flight and strong enough to handle taking the lift loads >to the spars. Keep the ribs two inches thick and don't put -big- holes >in them. > >Well I've said my piece...these things do perform some structural tasks >even if just to stabilize the "primary" structure so take the >"non-structural" statements as "secondary structure" and you'll be >alright. > >-Peter- > > >> > The turtledeck,indeed the whole top everything is not structural, so >> >you could make it removeable, some people have done that. >> > >> > Robert Covington > >> >> Gee, since the weight is already there, it seems that someone would >> have made it structural... >> Vince Bozik - Athens, Georgia I was referring to the whole top of everything on the fuselage, not the wings in any way, just to clarify. I have heard the non-structural mention about the top from Jeannette, I am pretty sure. The Wings do definitely transfer the loads to the Spar caps and stiffen the wing torsionally. I think if you were going to make your turtledeck removeable,one should use a real long piano type hinge all the way down both sides. If you are worried about stiffness, then glue plywood across the top to completely enclose the fuselage, then make cutouts a la the WAR type replicas. That way you would still have access to your goodies, and more stiffness with not too much weight. I would just make access panels and forget the removeable method. :) You can always find a runt kid to go spelunking in there. Well,maybe. A&P level kids are hard to find I guess. ------------------------------ End of krnet-l-digest V1 #8 ***************************