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 on: Today at 10:18:19 AM 
Started by Fred Cronenwett - Last post by john e. holliday
Thanks for lots of great pictures.   The last one of the flood line is hard to imagine.  How did Valley Park escape?

 on: Today at 10:12:07 AM 
Started by john e. holliday - Last post by RknRusty
Doc, our rainy day was not quite as dramatic as that, but it did take its toll with dropouts for Sunday's main Stunt events. We were down to three Experts and barely enough judges to get the job done, and the "impending storm" petered out, leaving us with overcast skies and a gentle steady breeze blowing in cleanly from across the flats. A CLPA pilot's dream day. Though on the lower circle where my Intermediate and Beginner gang flew, we did splash a couple of landings. When the sun finally showed itself, it was at our backs for all but the OH8s. Another great weekend at Huntersville is In The Bag!

 on: Today at 10:04:44 AM 
Started by #Liner - Last post by Tim Wescott
Do you mount the clunk tank center line even with center of motor or do you raise it up like the metal ones?

Raise it up.  But you may not be happy unless it's a uniflow.

Uniflow is just a line feeding the motor with one vent line correct? Not 2 vent lines?

I just looked for the n-th time, and couldn't find a discussion of a uniflow tank that I really like for your purposes.  This one is technically very correct, but a beginner to the concept may find it overly technical, and it's aimed at the RC helicopter pilot, so for us there's added clutter that we don't need.

The basic idea of a uniflow is that in flight you have one operating vent that's located correctly, submerged in the fuel, during flight.  By the magic of hydrostatics, the pressure at the submerged end of that uniflow tube is equal to the pressure at the tank end -- so it's either at atmospheric pressure or at muffler pressure.  By putting the uniflow tube close to the pickup tube, you ensure that the pressure at the pickup tube is also close to atmospheric pressure.

You can't determine whether a tank is uniflow by counting vents: you can have a hundred vents in a tank; as long as 99 of them are blocked off and the last one open is in the right spot inside the tank then your 100-vent monstrosity will be a uniflow tank.

Note also that a uniflow tank doesn't have to be metal, and it doesn't have to have fixed feed tubes.  You can make a uniflow clunk tank either out of metal or out of an RC clunk tank -- just put the vent in the right place.

 on: Today at 10:03:54 AM 
Started by Randy Powell - Last post by john e. holliday
Waiting on laser cut ribs I suppose?    Are we getting lazy? Layingdown Layingdown Layingdown

 on: Today at 10:02:42 AM 
Started by Sport Pilot - Last post by john e. holliday
Can't remember the weight, but power was an OS .35.

 on: Today at 10:01:02 AM 
Started by LARRY RICE - Last post by john e. holliday
Larry,  hope you enjoy retirement.  I know I did not get all the kits I wanted.   Thanks for all you have done. Hoff

 on: Today at 09:59:04 AM 
Started by Jim Roselle - Last post by john e. holliday
The OK Cub .049A came with attached fuel tank.   The OK Cub .049B came with a smaller tank that attached to the back plate and were beam mount engines.  I think the .049A was the only engine in their line that was not a beam mount.  They did have quit a few sizes of engines.  I think they did try a reed valve that was not too successful.  Still have my little .049A some where in the shop.   Guess that is the reason I got away with flying on 25 foot lines in the back yard.  My favorite was the American Boy.   Looking for some thing else I found an original kit in the shop.   Even has lines and handle.

 on: Today at 09:49:13 AM 
Started by Matt Piatkowski - Last post by Tim Wescott
I could not check the bearings after the crash as I do not have the tools required to completely disassemble the engine and put it back together.

Didn't you have the piston out of it?  Most engines of that type will cough up a crank if you just lightly tap it out (but -- I don't have a Jett-anything so I may have my head someplace dark and warm).

It is possible that one or both bearings have some internal damage to the rings or/and the balls retainers (baskets) as there is a very weak clicking sound coming from inside but only from time to time. This sound is very weak and there is no resistance associated with it.

If you can get it down to the point where the piston is out (which you have) you should be able to do a quick functional test -- spin the crank, and feel to see if it turns smoothly.  If it feels like there's gravel in there, or if it wants go to some preferred position, then the balls or races are damaged.  If the bearings are the culprit, the nose of the engine would be getting hot-hot-hot.

There is also a little play ( ~0.03") on the shaft along its axis. Simply: when the shaft is pulled and pushed, the end moves ~0.03" back and forth. This play is not present when the propeller is installed - only when the shaft threaded end is held by fingers and pushed or pulled.

This sounds normal to me for this general kind of engine, but I've never had a Jett, so...

Question: how hard can I torque the head mounting screws in order not to damage the Aluminum cast cylinder? I wonder if the RPM problems are not caused by the fuel leak between the button and liner. I cannot see anything leaking there when the engine is running but perhaps the shim was not squeezed enough?

Oh noooooo!  I couldn't give you a torque number, but if you reef on the bolts at all then you'll warp something.  If the thing won't seal correctly with the screws put in so they're just barely tight, then reefing down on them won't make it seal.  With metal to metal seals like this you're more likely to make them leak by over-tightening than by under-tightening.

You're clearly approaching this with the attitude of wanting to fix the engine yourself, so forgive me if I step on your toes here -- should you be considering sending it to Randy, or to some guy who's last name is Jett?  It may cost you a few bucks, but you'd get back a known-good engine, or a good story on why it's not worth it to pursue the matter.

 on: Today at 09:48:36 AM 
Started by john e. holliday - Last post by john e. holliday
Charles, I'm one of those that doesn't worry about weight when finishing.   I don't even strive for 20 point finishes.  Jim Lee said one it would be nice if I learned how to finish a plane.  Was always taught to build straight,  light and a good finish.

 on: Today at 09:42:53 AM 
Started by Don Hutchinson AMA5402 - Last post by Don Hutchinson AMA5402
Not the P-36, however if I had been thinking I would have made provisions on the drawing of the P-40 so one could build a 36, as well as the 40-C or 40-Q from the drawings! Actually, anyone could add the radial cowl and have one.

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