Curtiss Jenny Restoration

Welcome! We hope you enjoy following the restoration process of a 1918 Curtiss JN4D Jenny. Once completed, the aeroplane will be flown and displayed at the Candler Field Museum in Williamson GA (30 miles south of Atlanta). You can contact me below by clicking on "VIEW MY PROFILE"

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Location: Peachtree City, Georgia, United States

Thursday, November 27, 2014

Happy Thanksgiving and some Old Pictures

Jon Karkow emailed me the other day and said he was cleaning out some stuff and found a couple of photos of Jennies from 1918.  Thought you might like to see them.

Jon wrote:    got those probably 40 years ago from the National Air and Space Museum Library. It used to be that near the entrance to the library was a bin of excess materials that they sold for cheap. I imagine that this was duplicate stuff that they did not need.

Thanks for sharing, Jon.

Several posts ago I published two pictures of Charlie Meyers barnstorming in a field somewhere.  I wasn't sure where the photo was taken, but I thought it was a quintessential barnstorming scene - plane in a field of grass surrounded by curious onlookers.  Here they are again.

Well, last month I found out what eventually happened to Charlie Meyers and his Jenny.  Like most barnstormers operating in the north, he headed south for the winter.

He ended up in Bowden, GA where I found this story.

So there you have it !!!  Man, I was born too late.



Tuesday, November 25, 2014

Jenny Film

Remember several months ago, filmmaker Dorian Walker created a documentary about the Jenny?   

I'm happy to say the film is done and on November 13th NETA, one of three national distributors of PBS programming made the film available to all PBS station members. 

In case you didn't see it before, here is a link to the clip:

I can't tell you exactly when PBS will broadcast the movie.  All you can do is contact your local PBS station and ask.  Another way is to search on the local PBS station's website.  
If you are like me, you don't want to wait until PBS figures out when to show the film.  You can get a DVD sent to you by going to :

Hope you get to see it!



Sunday, November 23, 2014

Hisso update - John pulled the pistons and checked the rings.  The pistons looked good, but the rings were worn beyond limits.

Here you can see they were worn beyond even the "used limits".

Needless to say, we are looking into having new rings made. This was causing the crankcase to become pressurized.

I was also worried that the water jacket was leaking.  But on a good note, the jackets held air.

John had to build a special jig to remove the valves.

OK, we are even - one bad thing (rings) and one good thing (water jacket).

Add one more to the bad column.  Most of the valve guides were worn beyond limits.  We are going to have to sleeve them back to size.  More on that later.

John also split the case and measured the four crankshaft bearings:

Add one more to the bad column.  The front and rear bearings were fine.  The middle two were shot.  They were very far out of limits.  These bearings are poured babbit and will have to be replaced.  We are looking into that process.

Here is a picture looking into a cylinder when we disassembled the engine.  Add one to the good column - the cylinder walls were not badly pitted.

We had to order a special size hone, but the cylinders cleaned up nicely.

The score: 2 to 3

Good - Water Jacket, Cylinder Walls
Bad - Rings, Valve Guides, Bearings.

Hey, we can't end on a losing note.  How about a little humor:

Anyway, Dorian Walker just sent me pictures of his Jenny.  Thought you might like them too.

More soon.  I have a few other things to tell you but I have to run the kids to various functions critical to their social needs!



Sunday, November 09, 2014

Hisso Engine update

You know, I kinda stopped posting on this website because the Jenny has flown and I figured it's purpose had been complete.  Remember, this was not a shrine to me, or Ron, or Brian Eberle, but rather a resource for other future Jenny builders.

As I mentioned in a previous post, I didn't want to post pictures every time we flew the airplane.

And I didn't.

But recently we had an issue with our Hispano Suiza engine.  I wasn't going to post anything.  The Jenny had flown and the website had a beginning and an end.  But a good friend of mine suggested that I should post again because the issues we were having with our engine are Jenny related.  Most of all, a future Jenny builder may benefit from our findings. He was right.  Here goes.

This is how a small leak can turn into a major overhaul.

After several hours in the air, we noticed that oil was leaking out of the two camshaft towers in the back of the engine.  Now I know having oil on your shirt after flying a Jenny all day was cool, but it should not have been leaking.

It was leaking so much, we were carrying a rag in the cockpit to wipe the windshield every hour.  The tower has a clip (you can see it here) and a gland nut.  We removed the clip, added some liquid gasket maker and screwed the gland nut back in place.  The problem was that the clip had a 90 degree turn on the end, the point which dug into a hole.  This kept the nut from spinning.  When we tightened the nut, the old hole was nowhere to be seen.  If we loosened the nut and found the hole, the nut was too loose.  Hmmm....

After pouring through the Hisso manual, I found that the nut should indeed be tightened and a new hole should be drilled.  I didn't like hearing that.  I had visions of the drill shavings falling into the tower and clogging up some important oil passage.  Another manual gave a better solution.  You only drill half way into the tower.  That's exactly what we did.  The clip was re installed and the leak was fixed.

Lets fly some more.

We noticed another leak developing.  This one was located at the crankshaft seal right behind the propeller.  It started out as a slow leak, but the more we flew, the more the oil leaked.

That will be an easy fix, right?  Just a prop seal change.

Off came the propeller.  We removed the gland nut and the clip.  Much to my surprise, there was no prop seal !!  Did the guy who overhauled the engine forget it?  No use crying about it now.  Let's install a new seal.  There was a race inside the crankcase.  We figured a seal should go there.  We purchased some graphite water pump packing material from MSC and pushed it in the race.

It was rather tricky because the packing had to fill the race but could not interfere with the gland nut.  Next question : what is the proper torque on the gland nut?

The nut pushes against a large ball bearing on the crankshaft.  The Hisso manual said you should tighten the nut "until the bearing will spin two revolutions on it's own after spinning by hand".  Oh boy.  There is no way we could test that.  So we tightened the nut until it seemed right.

It was time to run the engine again.  The prop was re installed. The primer cups filled with gas.  Ignition on.  Spin the propeller.  Engine fires on the first blade......and oil pours out of the new front seal !!!

Now I'm getting worried.  Ron Alexander always said sick engines give you signs.  What was going on here?

There were many sleepless nights.  More time was spent reading the manual.  I learned that a crankshaft seal wasn't necessary.  The gland nut was designed with grooves which forced oil back into the crankcase.

I talked to every Hisso expert I knew - Frank Shelling, John Saunders, Paul Daugherty, Mike Damiani and Jack Kearbey.  Each one told me something to try.  But we could not get the leak to stop.

"Check the breather. It may be blocked," everyone agreed.  I pulled the breather.  It was free and clear.

We made the decision not to fly the airplane until we figured it out.

Finally, John Saunders gave me the name of the man responsible for maintaining the Hisso engines for The Vintage Aviator Co. in New Zealand.  Dave Cretchley offered the following suggestion.

"Do a compression check."

The next day we hooked up the differential compression tester and pumped 80 pounds of pressure into each cylinder.  The results were abysmal.  Not one cylinder held more than 50 pounds.  Three had 30 pounds and one had 10 pounds !  Now we know the problem.  The piston rings were bad allowing air to pressurize the case.

Air was rushing out the breather like a hair dryer.  We had serious issues.

A decision was made to pull the engine apart.  All we had to do was pull the cylinder banks, quickly hone the cylinder walls and put it back together, right?

We took the engine back to the shop and started removing the accessories - mags, water pump, intake tubes etc.

The entire cylinder bank comes off in one piece.  We found out a normal wrench would not remove the nuts between the cylinders.  They were too close together.  The Hisso manual showed a special tool needed for the job.  I borrowed one from Kevin Connor.  Before long, the cylinder banks were removed.

Luckily, we had purchased two spare cylinder banks (seen above on the left and right).  After taking off the banks, we started to wonder.  How was the rest of the engine?  We had our doubts.  The Jenny was a valuable aeroplane.  We had poured seven and a half years of love into the restoration.  Did we just want to throw this engine back together and go flying again?

I have a builders mentality.  My wife rolls her eyes all the time whenever I look at something and say "I can fix that."  I started off wanting to repair this engine on my own.  But the little guy who sits on your shoulder and whispers in your ear told me to swallow my pride and seek professional help. Do I have a valve seat cutter?  Nope. How about a 4.75 in hone?  I do not.  Can I make a new valve guide?   Maybe, but it would be my first.

I had been watching (with interest) John Gaertner at Blue Swallow Aircraft overhauling two tired OX-5 engines.  These boat anchors left his shop in better than new condition.  I wanted the same for our Hisso.

That's enough for one blog entry.  I'll post another one soon starting with the arrival of our engine at John's shop.  What he found was very interesting.

Till then....enjoy