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

Monday, December 22, 2008

Tail skid fitting

The wooden tail skid pivots on a metal fitting bent around the skid tube and I decided to tackle this part today. This drawing was available and it was easy to transfer the dimentions to a paper pattern.



The steel is pretty thick stuff - .100 steel - guess they wanted the tailskid to be strong. Anyway, the only way to bend metal of this thickness is to heat it with a torch. I bent it over a spare piece of 1 in. tubing (same as the skid tube) using a lot of heat and a bit of persuasion (hammer).



After transfering the paper pattern to the steel, I couldn't cut it in the bandsaw any more. The bend took care of that. So, I reverted back a tried and true method - the hacksaw! It worked perfectly.



The grinder took care of the rest.



Here is the piece after grinding.



And trial fit into place.



From my calculations, there is a 1 in. gap between the tube and the skid. This allows room for a bumper pad. Next step will be dressing the fitting and drilling the holes.
Till then
Brian

Friday, December 19, 2008

Floorboards

Well, the kids are home from school for the Christmas holidays, but they ran around all day today playing with the neighborhood kids and I had several hours of uninterrupted shop time.

I decided that the floorboards needed to be made.

First, the ash planed to 1/4 in was cut to size.



OK - here's the kicker. The floorboard drawings that I have are wrong. Paul Dougherty warned me about this so I did the next best thing - I took drawings off his Jenny! Hey, it worked for him and he measured a bunch of other original Jennies which saved me from doing it. Anyway, the floorboards were cut to 7 3/4 in. width. The front length was 27 3/4 in. and the rear length 29 in.

The drawings commonly found are from a JN4-D2 which is a little different than the JN4-D. Same goes for the floorboard support drawings. They are incorrect.

The floorboard supports are spruce cut to a uniform 1" thickness. It also has a 2 in. radius curve to rest on the longeron. Since there are several supports, I made a simple pattern.




Everything was cut to shape on the bandsaw.



And sanded to the line on the oscillating spindle sander.



Here are the rear floorboards in place. I cut the supports a shade higher so I can cut them to match the longerons later. Basically, the rear floorboards are 2 1/4 in. above the longeron. This gives the floorboards a downward angle and they do not match the trailing edge of the front floorboards. Don't panic! This is the way they go. The height difference is to allow the torque tube to clear the rudder bar.



The rear floorboards are different. They go from 3 3/8 in. at the back to 1 1/4 in at the front. These floorboards are level with the airplane.



Since it was still warm outside, I gave everything a first coat of varnish.



Enjoy
Brian

Tuesday, December 16, 2008

Tail skid area

I had great intentions of getting a lot done on the Jenny over the last two days, but I walked out into the shop yesterday morning and watched water pour out of the hot water heater.

Needless to say, I had to try my hand at plumbing.

Now that the tailskid tube was bent to shape, I made the bushings out of phenolic sheet. The bandsaw made the square and the belt sander made it round.



I also finished the tail skid. The upper end (where the bungee wraps) has a 1 1/8 in. radius on the top side and the corners were routed 1/8 in.



I also drilled a pilot hole at the pivot location.



When the tail skid reaches full travel, it is stopped by two pieces of plywood. These were cut to with their respective angles.



I spent a lot of time fitting the tail skid tube. The reason there is a fiber lock nut on the bolt is because I lost count of the number of times I removed the tube, made a slight bend adjustment of the tab, put it back in place and done it over again. The temporary nut was easy to remove and replace.



Sometimes, when the tab at the top was bent, you had to adjust the tab at the bottom and vice versa. It was tedious but eventually I got it right.



Here you can see the plywood stops in place. As the tube moves left and right, the end of the tail skid hits some rubber "bumpers" on the plywood. These will be installed later.



Since we've had unusually warm weather in Atlanta this week, I was able to put a first coat of varnish on the skid and the stops.


Enjoy
Brian

Monday, December 08, 2008

Tail Skid

Now that the bend was completed, both ends had to be flattened and bent so as to fit the top and bottom of Station 11.

The tube was flattened by simply squeezing it in a vice. Because the metal was already stretched, I decided to heat the bend.



This is how the tube fits in Station 11 (upper). Noticed the flattened, bent tube.



Here's a picture of the tube with both ends flattened and bent.



The plans call for the flattened tube to measure 0.233 in. A doubler of .063 steel was cut from stock and everything was ground to the 22/32 in. radius called by the drawing.




After tack welding the sides, the back part of the doubler was heated and bend to match the tube.

Here's a completed end.


Here's the tube cooling after both the ends were finish welded.



This is how things will go together. Watching the individual parts come together is neat, but this kind of gives you the big picture. Bungees will wrap around the tube and skid and I have to build the pivot next.


Till then....enjoy


Brian

Saturday, December 06, 2008

Tail Post Tube

In my opinion, the hardest piece on a Jenny to make is the tube that holds the tailskid in place. It's a 1 inch tube of .058 thickness bent past 90 degrees (106 degrees to be exact) across a 1 in. radius (tight).



I decided to try and bent the tube with my three-die bender and a 1in. die. At .058, the tube was too thick to bend cold so heat was needed. My neighbor Nick Ballay came over to lend some muscle (see picture below) and we heated the tube with the torch.


The tube would bend all right, but when we tried getting the 1 in. radius, the tube would kink. After three pieces of tubing, we gave up. There had to be a better way.

I called Paul Dougherty. He made his Jenny skid tube on a vice. No Dies. No hydraulic bender. Fellow Bucker restorer Robert Johnston stopped by and I asked him for advice. Robert owned a machine shop for many years and he agreed with Paul's advice. He also told me a few tips (which you will read about later).

So, I borrowed some of my kids play sand and filled the tube. This prevents the tube from kinking easily. Just pack the sand into the tube and tape both ends.




Put the tube in the vice and start heating with the torch. Robert gave good advice here. He said you should heat the inner and outer radius of the curve. The hot metal will stretch (outside) and shrink (inside) while hot. He also said not to put the torch on the top and bottom. This is where the tube will kink and heating it will weaken the wall and actually make it kink easier.

Also, take your time. If you heat one tight spot and bend there, it will kink. I heated one area, bent a little, then heated next to it, bent a little, then heated the other side of the first bend and finally worked over the entire area. Sure enough, the tube began to move.


Heat the outside and the inside (not the side)


Another thing I learned - get the outside hot (red, but not melting) then heat the inside and start pulling. Not too much. You can feel it move. Slowly is good. Then go back to the outside (while the inside is hot) and pull again. You can see the amount of area I heated in the pictures.
This method worked perfectly! I got the 106 degree bend with little trouble. I guess the entire heating process took about twenty minutes or so.
More later.
Brian

Tuesday, December 02, 2008

Tail Skid

I started working on the ash tailskid recently. From the original cashe of lumber we got at Atlanta Hardwoods, I had a plank planed to the rough dimentions from the tail skid drawing. Phil Mintari gave me an original Curtiss tailskid, but it was too short when compared to the drawing. It was, however, great for figuring out the shape.


After the dimentions were penciled onto the plank, the bandsaw was used for the rough cut.

And the oscillating spindle sander was used to sand to the pencil line.


Next, the markings were drawn to represent the tapers. The skid actually had an "airfoil" shape. The front and back were not symmetrical.



I did all the shaping with the hand sander and coarse grit (80 or so) paper.

Here is the trailing edge before hand sanding with 220 grit.



The leading edge was shaped in the same manner, but it had a gentle 3/4 in. radius all the way around. Below is the tail skid in place. I can fantasize, can't I? I still have the tubing structure to build yet before this picture becomes reality.


One of the enjoyable aspects of rebuilding this plane is the opportunity to meet many people. The other day, Tom Hegy stopped by the house on his way to Florida.



When I first started the Jenny project, I figured that it would take me some time to find an engine. After all, Hisso's aren't very common engines and the people who have them aren't too willing to part with them (says something about the engine). Anyway, I put a blind ad in Trade-A-Plane and Tom called me right up. He didn't have an engine, but he knew somebody who did and that was the engine we ended up getting! I thought that was a nice thing to do.
I have come to find out, Tom is truly that type of person.
I spent the afternoon with Tom and could not have had a nicer time. He still dusts crops during the Wisconsin summers (as he has done for the past 45 years) and tinkers with his own antique airplanes during the other times. I was glad he came for a visit.
Cheers
Brian