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I beg to differ with you Richard. With all due respect to Wayne, I see no resemblance to the Matco 1X/2.5X diagram's geometry and the Velocity built hanging pedals that Wayne used. [upside down or not]

The pointload on the end of the ram should be way closer to the pivot. Wayne and I have talked about this and he is comfortable with it....but it still doesnt appear to have Matco's desired mechanical advantage they diagram.

 

I only bring this up because at one time many were trying to fabricate the hanging pedals, and everyone was copying everyone else, without looking at the Matco diagram.

 

Below appears to be the Velocity hanging pedals geometry.

YMMV

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We agree, I just can’t construct an intelligible sentence. :o

The brake pedal is a lever, if the cylinder is mounted at the pedal there is no leverage and the force applied to the brake cylinder is the same as the force applied to the pedal. If the cylinder is mounted halfway between the pivot and the pedal the leverage is 2:1, giving twice the force on the cylinder(and twice the movement at the pedal). Steve's cylinders appear to be mounted a quarter of the way from the pivot to the pedal for a 3:1 leverage. Wayne's cylinders appear to be about three quarters of the way from the pivot to the pedal for a 1.3:1 leverage. Matco suggests 2.5:1 or more.

The fact that there is a pivoting arm attached to the cylinder to allow for rudder deployment doesn’t affect this, it is where the cylinder shaft intersects the the brake pedal arm that determines the lever ratio. If the pivot arm is flipped as Tmann suggests it will improve the ratio, but the brake cylinder will be mounted at an angle to the force being applied introducing trigonometric effects. Depending on the angle, this might result in non-linear pedal force feedback, I.E. the further the pedal is pushed, the softer it will become.

 

Now that I look at Wayne's again, it appears that there is a significant angle between the line of action of the brake pedal force at full depression and the line of resistance from the cylinder. This will increase the pressure on the cylinder for the same force on the pedal, acting like a longer lever arm but in a non-linear fashion. If the stroke of the cylinder is short enough, and the radius of the circle it moves along is large enough, the force would not change enough over the pedal range to be noticeable. If all the angles are known the total lever ratio could be figured out exactly. Translation: It might work :)

Wayne is clever :thumbsup:

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One of the wheel/brake companies (MATCO ?) had a nice demo

showing the need for mechanical advantage at Oshkosh.

 

A seat, two pedals, two master cylinders, two gauges.

Left with a 3:1 advantage, the right with 1:1......

 

It gave an instant education as to which design worked.

 

(The one without mechanical advantage also showed all the abuse it

had received by those trying to equalize pressures with a HEAVY foot !)

 

John

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Oops, the numbers above are wrong. The ratio lengths should be measured from the fulcrum point. The Matco recommended ratio is actually 3.5:1 and the ratio for Steve's pedals should be approximately 4:1. The 1.3:1 is correct.

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My friend Mark--also building a LEZ--came up with a nice bellcrank arrangement to take his push-pull cable straight into the Ellison TBI. I think I'll try something similar. His Ellison is mounted on an elbow facing forward. He didn't have room in his cowl to let the cable turn the usual 90 deg angle.

 

In pic 1 you can see the push-pull cable coming from the firewall at the top left corner of the pic. It moves a bellcrank mounted on the aluminum piece which actuates the Ellison slide left and right. Although the bellcrank is moving in an arc, there is very little angular displacement so it works very well. His mixture control works nicely, too

 

In pic 2, you can see the bellcrank a little better. Thanks Mark.

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I only see pull :confused:

no push.

It seems as if the pull of the cable is countered by the pull of the springs. This arrangement is great if you have limited space for the thicker, less flexible push-pull. Additionally it functions as a "safety net in the case of control cable separation in that the throttle will go to max and the mixture to rich (if that is the way it is set up.)

 

There are some serious drawbacks (personally experienced). If the cable is restricted at any point between the control and the shaft on the carb, there is no tactile feedback indicating that the mechanism is not working or is jambed (when going to low power to higher power). This is not too important on T.O. as you will get no thrust (and probably perceive that something is wrong), however if it happens in flight, after a reduction of throttle, perhaps when approaching a landing, and you wish to add power, the lever will move, the only problem is that that engine will not respond. --Low, relatively slow and no power-- not a good situation to be in.

 

 

In my case, in my dragonfly, it appears as if a heat shield expanded somewhat and jammed the throttle body bellcrank. On leveling off, the addition of throttle had no effect, the engine merely purred along at idle speed. Post mortum (or flyum) showed no control problem-- probably because the mechanism cooled and recovered to its original shape.

 

The lack of feedback from the throttle (as in the jammed bellcrank) ate up some gliding time while trouble shooting and trying to get the engine running at power again. (I lived but the aircraft suffered fatal injuries).

 

As a result, I will use nothing but a Push-pull system for Power. If I use a boink-boink engine, the same goes for mixture and prop.

 

I said to my plane, and future projects, "Fool me once, @#$% you, fool me twice, @#$% me!":mad:

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My friend Mark--also building a LEZ--came up with a nice bellcrank arrangement to take his push-pull cable straight into the Ellison TBI. I think I'll try something similar. His Ellison is mounted on an elbow facing forward. He didn't have room in his cowl to let the cable turn the usual 90 deg angle.

 

In pic 1 you can see the push-pull cable coming from the firewall at the top left corner of the pic. It moves a bellcrank mounted on the aluminum piece which actuates the Ellison slide left and right. Although the bellcrank is moving in an arc, there is very little angular displacement so it works very well. His mixture control works nicely, too

 

In pic 2, you can see the bellcrank a little better. Thanks Mark.

Pull only cables are lawnmower technology on a plane. It relies on the spring to get full throttle or mixture. if the spring breaks or the cable gets stiff and the spring cannot over come the stiffness you are done mowing the lawn on your new farm. if the mixture spring breaks or comes off the mixture will go to idle cut off as you try to lean during cruse. lean to far and it will quit with no way to get it back running. this has already resulted in several people owning farms.

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I am not to the engine point in my build yet but this whole linkage bit has me thinking:

 

If you are running with fuel injection, is there any need to have a throttle connection that penetrates the firewall?

I would think that you just need to 'talk' to the ECU.

That would not require the 'long linkage' all the way through the firewall ...... would it?

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It seems as if the pull of the cable is countered by the pull of the springs.

Rich, Tmann: You are looking at the mixture control; the spring you see is to pull the mixture to full rich if the mixture cable separates. However there are no springs in the throttle linkage/bellcrank. The shaft of the push-pull cable enters at the the upper left corner of the picture, actuates the bellcrank, which moves the Ellison throttle slide.

 

Pull only cables are lawnmower technology on a plane. It relies on the spring to get full throttle or mixture. if the spring breaks or the cable gets stiff and the spring cannot over come the stiffness you are done mowing the lawn on your new farm. if the mixture spring breaks or comes off the mixture will go to idle cut off as you try to lean during cruse. lean to far and it will quit with no way to get it back running. this has already resulted in several people owning farms.

Lynn: As you know, many carburated aircraft use pull-only cables for mixture control with a spring backup to the full rich position. I've owned three airplanes with that setup. On my aircraft, the cable would move the very light mixture lever even if the spring breaks. This lawnmower technology works fine if such things are taken into consideration, inspected and maintained.

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I am not to the engine point in my build yet but this whole linkage bit has me thinking:

 

If you are running with fuel injection, is there any need to have a throttle connection that penetrates the firewall?

I would think that you just need to 'talk' to the ECU.

That would not require the 'long linkage' all the way through the firewall ...... would it?

 

Yes you do T,

 

The electronics can control the spark and the on duration and timing of the open EFI(njectors) or the mechanical air gizmos control the amount of fuel that is constantly sprayed, hopefully at the intake valve, in the case of the bendix non-electronic type system. You still must control the amount of air that the cylinders (or trochoids) can get in a cycle which directly influences power production. (thus as you decrease the throttle setting closing the throttle plate, the manifold pressure goes down creating a greater vacuum relative to ambient. At full throttle, you read close to ambient because of less throttle plate (or whatever) restriction.

That control is a mechanical movement at the throttle body at the engine. Thus the penetrating control.

 

This intake manifold vacuum was used on cars, in the past, to actuate windshield wipers (anybody have a Gremlin and tried to climb a hill with the windshield wipers working?) and to actuate heater air directors. It was also used to mechanically change the timing (I seem to remember)

 

The fuel injector mechanism is necessary to control the amount of fuel injected to give you an air/fuel mixture that will burn at all. Too much fuel per air or too little per air, you get nothing. The amount of fuel required for any throttle position will be in a fairly restricted volume range (controllable by the mixture control. (ie full throttle-plate full open idle with the plate closed-there is some opening to allow the engine to run at idle(adjustable stops)).

 

As you close the throttle plate (toward idle), the MP decreases (suction in the manifold increases) as the descending pistons try to suck air past the closing plate, through the open intake valve or port in the rotary, the sensors (mechanical or electronic) sense the decrease and spray less fuel. In a NA engine, there is always suction in the intake manifold.

 

On the other side is the turbo or supercharger which pumps air past the plate still necessary for air volume control) increasing the amount of air (increased density because of the charger) per intake stroke, to the cylinders. This increased amount of air (mass not volume) must be matched by an increase in fuel delivered via the above mechanism.

 

To clarify further, each intake stroke of the piston or rotor will bring in the same volume of air through the intake system NA or Turbo'd. That is a product strictly of the displacement ( and a few other things. --for you purists--) )Adjusting the throttle plate and/or using the turbo etc does not change this volume, but does change the density of the air charge and thus the number of reactive molecules that are available for the fuel that is metered.

 

Mazda, in it's new Renesis has an electronic throttle where only wires need to penetrate the firewall, but I have nixed that idea based on my prior posts.

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Rich, Tmann: You are looking at the mixture control;

Thanks for the orientation, I forgot that the Ellison has a slide body throttle and was looking for a push-pull on a bellcrank. My eye went up to the pull/spring control above the throttle body. Probably Carb heat.

 

Why is it that somebody has to have neon lighted pointers to show you what is right in front of your face:irked:

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For the throttle mechanism, the pull only cable was ok for an engine without an accelerator pump. Even the CPs note that if you cannot actuate the throttle without the springs that you have a "down" aircraft (my words). The springs purpose was to only take the sponginess out of the system---not to make it work. Obviously with an accelerator pump, you will never actuate the throttle with the springs off.

 

From CP65 page 13 (in part): "The throttle and mixture both should be set up and adjusted so that they will work with no springs installed. The springs should be installed so that they pull the throttle to full power and the mixture to full rich in case of cable failure."

 

From CP78 page 2: "Before your first flight, and at regular intervals thereafter, get someone to help you check that the throttle and mixture controls do indeed, move the appropriate range to the full throttle/full rich positions and also to the idle/cutoff positions WITHOUT the use of any helper springs. If you cannot get the throttle and mixture controls to work satisfactorily without springs, consider going to push/pull cables. I realize this is a hassle, but not nearly as much of a hassle as losing control of your engine at a critical time."

 

Biggest tip to make the push-pull work well:

Once your cable bracket is made and on the aircraft (I used a modified Vans Aircraft bracket), take a scrap piece of push-pull cable (with all the end pieces attached) and use that to find out where the cable wants to penetrate the firewall. The scrap piece needs to be short enough to move around---and long enough so that you can mark the firewall with a pen. If you don't do this, the small "kink" going thru the firewall---then the short distance to the bracket will put a lot of friction in the system.

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I saw all this vacant space behind the sump and thought I could fit a square paper filter there. Came up with the first iteration (pic. 1) which might have worked but was clunky and would've required a deep cowl.

 

Then I thought "Maybe I can fit the filter between the firewall and engine" and was well along on the second idea (pic.2 ). After discussing with friend Mark, became clear it was just too tight and going to be hard to incorporate carb heat.

 

So I ended up making a filter box based on the box Vans vends and put the oil cooler in the space behind the sump. Had to extend the firewall to hide it all but I think it will look good and be fairly slick--hope the oil cooler cools. Hat tip: W. Blackler for the oil cooler door idea (pic 4).

Looks very good kent :-)

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Looks very good kent :-)

Thanks, Wayne.

 

Reminds me to add some cowl-in-progress pics. I covered the engine with heavy paper (pour foam didn't want to stick to plastic wrap that I used first), glued some blocks of blue foam on the engine high points and filled the area with pour foam. "Sand to a pleasing shape" or until the blue blocks start to show. Fill the shape with fast-setting joint compound, a coat of latex paint, several applications of mold wax, painted-on PVA mold-release. Then five layers of BID. After cure, trim to leave a 1.25" flange or so at the firewall.

[Edit: whoops pics are too big I guess. Add later]

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I'd use a red Morse (33c?) marine throttle/shifter cable that has been used on boats for many years. Positive actuation of whatever you're trying to actuate and they last a long long time. It might not be the lightest possible part but it works and if you install it right then its done.

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I'd use a red Morse (33c?) marine throttle/shifter cable that has been used on boats for many years.

Yes, I thought I'd try marine cables. From perusing the West Marine catalog, they look pretty good except you can't get them in custom lengths.

------

Here are pics of my cowl-in-progress (molds).

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First, thanks to Jon for getting his site back up.  

 

Well, five years later and my LEZ project is flying (pic).  You can see some more builder pictures and comments here

http://forum.canardaviation.com/showthread.php?t=4923&highlight=kent%27s+long-ez

 

I will try to discuss some things that worked and did not work.

 

DOWNDRAFT COOLING:  The NACA style scoops I had at first did not cool for squat (pic 2).  I could not even get up to pattern altitude before the engine began to overheat (425-450.  I like to see <425).  After one flight I trucked the airplane home and built some forward-facing scoops.  They have cooled pretty well but the left-fwd cylinder (#3) still got hot on takeoff/climb.  In cruise they are all pretty even.  I installed a small bypass duct in the left intake to direct air past the thin part of the fins (pic).  That helped.  I installed homemade piccolo tubes and a water manometer to check the pressure differential above and below the cylinders (pic).  Lycoming says an O-320 needs 5.5" of differential.  I am generally getting that but the left side is about 1/2" less differential than the right side and sure enough, the left side is generally a bit hotter.  I opened up the exit area a bit.  That helped a tiny bit.

 

I suspected that in climb, the flow over the strakes to the intakes was getting disrupted.  I oil-flowed that area and the surface flow looked pretty decent so I think the intakes are working OK.  The left side intake is stubbier than the right side and does not have the nice boundary-layer ramp as the right side.  Still, I don't think that's much of a problem.  I tried adding a flow-divider on the left side.  It had no effect that could tell.

 

Presently I'm revising the exits to get a more direct airpath out of the engine.   It is said that the exits need to be 2 to 2.5 times the inlet area.

 

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OIL COOLER:  This seems to be working fine.  On hot days with the cooler door open the temp gets to about 170. (180 is ideal).  At first, I had the cooler exiting into the lower cowl.  That was dumb.  Then I fabed-up an elbow and cut a hole in the cowl for an exit.   Presently, I have  no way to control the exit door but I'm making a device so I can set the door position on the ground.  It would be nice to have in-flight operation but I haven't figured out a good way to run a cable and I've found on my Cozy you can usually set up the cooler door on the ground.

 

First pic is in construction, fuselage inverted.  2nd pic with the added elbow. 3rd pic showing the exit.  Yeah, not ideal but it works.

 

ELLISON TBI:  The one on my Cozy works great.  On the EZ, at 1800 rpm or so, I was getting a slow pulsing hesitation  as if you had pulled the throttle back slightly and put it back up.  I made an air straightener which took most of that away

 

DOUBLE FACET PUMPS:  Because I have an O-320-H2AD motor with the mechanical fuel pump near the prop hub, I was afraid to use the mechanical pump with downdraft cooling, fearing that heat on the fuel lines under the engine would cause vapor lock.  So I used two facet pumps with shorter exposed lines and some hot-rod store reflective firesleeve over the lines.  I have not seen any problem with vapor lock so farr.  These particular Facet models do not have internal check valves and I found in testing the setup that I could not build pressure with both pumps on because there was some kind of back-flow in the pumps.  I added the Andair check valves and they have worked all right so far.   The reason I went that way is because a lot of Van's builders use that 2-pump setup.   BTW, the engine will idle on the ground with both pumps off but I haven't tested the gravity flow in the air yet.

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Looking good Kent.  Sounds like you're working everything out... good luck with the cooling.  Are you still in Phase 1 testing then?

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I still have a few hours to go.

 

This winter, I'm going to cut off a winglet and reattach it.  The airplane has a yaw.  You can see the misalignment in these photos.  The aircraft is roughly centered on the airport gate in the distance and I visually lined up with the winglets.  Take into account that the left rudder is streamlined, right is displaced outboard by a block but it is still easy to tell the winglets aren't matched.  I build in a basement shop and it is hard to confirm the alignment inside.  I remember having a problem with the location of the aileron cut-out that is used to set the winglets.

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Edited by kent ashton

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...but it is still easy to tell the winglets aren't matched.

 

It's probably me, but I've looked at these pics several times and I don't "see it".  I guess the best reference is to measure both winglet tops and bottoms to the nose at centerline.

 

Regardless, sounds like perfection will be achieved.  Looking forward to the updates...

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