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

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


Saturday, June 28, 2014

Sleeping Dog video

Sleeping Dog Productions has released another Jenny video.  Enjoy:

In other Jenny news, Dorian Walker and his crew are now touring the airshow circuit with their Jenny.  They made it to Dayton for the upcoming Air Fest.  From the picture, they are in good company.

I think it is great what they are doing with their airplane.  If you go to their website, you can learn more about their plans:


 And you want to see their Jenny fly, here is their touring schedule:

Today, my friend and future Jenny restorer Kevin Connor was visiting Old Rhinebeck Aerodrome.  It seems as if their Jenny is just hanging out until the next show.

Lastly, the Jenny in San Diego is getting new clothes! Fellow Bucker pilots Greg Stringer and Joe Vasile were there attending the Bucker fly-in and took a quick tour of the San Diego Aerospace Museum's Gillespie Field restoration shop.  

That's all the Jenny news.  Enjoy


Thursday, June 12, 2014

Vintage Days - Candler Field Museum 2014

Every year our museum has a really fun event called Vintage Days.  We have old cars, tractors, planes and people in period attire wandering around the grounds.  There were three local bands playing music, a guy selling home made ice cream churned by a hit-or-miss engine, local vendors selling all kinds of stuff and of course food...lots of food.  All the proceeds benefited the museum and our new Youth Mentor Aviation program.

Details and photos of the event can be seen at:

Twice during the day we conducted a "Parade of Flight" for the nearly 1500 people who attended the event.

I was privileged to take Vic Syracuse with me on the first parade.  Vic was the DAR who issued us the Jenny's airworthiness certificate back in November.

Luckily, I had two teenage student pilots as wing walkers.  It was a warm, summer Georgia Day and they thought nothing of it.

 John Gaertner came all the way from Virginia to be there and I'm happy to say he got to fly under the Jenny wings he built.  Here is a link to the video he took:

 Local aviation Photographer John Slemp took some great photos during the event.  He shared one of me and my wife at the end of the event.

He also converted a few of his photos into black and white.

You can see some of his work here:

It is a neat, simple website filled with some great aviation photographs.



Sunday, June 01, 2014

Alaska Jenny Pics

 A friend sent me these pictures of Alaska pioneer pilot Ben Eilson's Jenny. 



Ben Eilson had a fascinating life.  If you want to read about him, click on this link:

Anyway, Ben's Jenny hung in the rafters of the Fairbanks Airport terminal for many years.  The original wings had been lost and inaccurate replicas were made. You can see the wings in this photo.

Several years ago, John Morak contacted me.  He was part of a group of volunteers in Fairbanks who wanted to restore Ben's Jenny.  They needed some wing strut drawings and I was happy to oblige. 

As you can see, they did a great job.  If you are ever in Fairbanks, check it out!



Monday, May 26, 2014

Another video

Scott Coile took this video last evening and wanted to share it with everyone.   It was a beautiful evening for flying and we took advantage of it!

 Click here to see the video:

Weather permitting, we are going to fly the Jenny at our annual Vintage Day event at the museum.

You can see the schedule of events at



Monday, May 19, 2014

New Jenny video

The folks at Sleeping Dog Productions posted this three minute trailer using the Jenny footage they took last month. 

Click here to see the video:



Wednesday, April 23, 2014


Hi Everyone,

I have not posted much lately. I apologize.  We have been flying the Jenny quite a bit and I didn't want to bore anyone with posts that read:

Flew Jenny today
Flew Jenny today
Flew Jenny today.

I felt like unless something relevant came along, there was no need to post. Eventually I will share some really good videos of the Jenny in the air. We simply have not taken any worthy footage yet until a visit by Sleeping Dog Productions recently. (see below).

We have been spending time tinkering - oil changes, leaky valve covers, a flat tire....stuff like that. I guess you never just "get in and fly away" with an airplane this old.

One thing we noticed is that the bungee cords had been weakening.  When we installed the cords, we did it the old fashioned way - wound rib stitch cord around the lose ends and gave it a good coat of shellac.  This method didn't seem to work very well.  We didn't put the bungee cords on with enough tension to start (stretching as we wrapped) and not enough wraps with the rib stitch cord.

Live and learn.

So, the main landing gear got new bungees and we wrapped them with copious amounts of cord.

In the tail, we decided to go modern...

The wraps were held in place with hose clamps!  Sorry.


Since we were flying so much, it was time for another oil change.


And tracked down a small leak at the oil temperature bulb.


Somehow, we sprung a leak in the tube of the left wheel, so off it came.


And a new tube installed.

Our youngest son Brighton decided to polish the propeller.

He also got to sit through an engine run as we adjusted the idle setting.  About that setting.....


One of my complaints was that the engine hesitated when accelerating from idle.  It would shake, backfire and run rough for a few seconds before running smoothly.  I knew the NAD4 carburetor did not have an accelerator pump, but rather a small chamber filled with fuel that was accessed when the butterfly valves were opened with the throttle.  I wasn't happy with this set up.

So, I went into my Hisso manuals.  There was no mention of an idle RPM.

Since there was no guidance in the book, I set up the engine to idle around 350 RPM.  I was told these engines idle slowly so I used the idle speed of the OX-5 engine, another big water cooled V8.  

It finally took a few phone calls to Paul Dougherty at the Golden Age Air Museum and Kevin Connor in Tulsa, OK to figure it out.  Everyone told me "set the idle RPM high enough to where it runs smoothly, but slow enough that you don't move".  No brakes, remember.  The consensus was 500 RPM.

Ours is now set at 480 RPM and I'm happy with the results!

John Gaertner sent me these vintage Jenny pictures seen on eBay.  I love this one.  Could you imagine landing in a field of high grass and selling rides all weekend?

This one is a Standard J1, but you get the idea.

Last weekend, Sleeping Dog Productions came to the Museum and did a lot of filming.  They are planning on making several videos for Flying Magazine's online section.


 Also, Stan Smith sent me these photographs of the Jenny model he is building.  I was blown away!  Stan wrote:


Thought I would send you some progress pictures.  Have really been enjoying reading your blog and seeing pictures and videos of the flights.  This is the first time that I put the plane together and did a weigh in, (9 3/4 lbs. so far with batteries, motor, and servos inside)

Stan Smith

Also, Jim Landoni sent me pictures of the unbelievably scale Jenny model his is building as well.

Enjoy it all. I'll try to post more often again.