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, March 29, 2010

Control Stick Torque Tube & Spacers

Worked on the torque again tube today. Here you can see the right side of the tube bent back to level.

With some more heat, the other side was bent level too.

One of the key things is making sure the tube is straight. This required laying the tube on a flat table, measuring and adjusting accordingly. It's always fun watching the tube cool - it moves! But, after a few "tweaks" it came out reasonably straight.

By design, and for no reason I can give you, the floorboards are slanted. But, the torque tube is level, remember? So Curtiss used wooden shims to level the castings.

By leveling the tube, I measured 9/16 at the highest end and 1/4 in on the low end.

So, A board of sufficient width was planed to 9/16 in. and with some 80 grit sandpaper, tapered to 1/4 in.

The finished board.

Then the outline of the casting was traced on the board...

...and cut with the scroll saw.

Ah, my beloved spindle sander...being used again.

Here is the spacer in place.

One clearance issue is the control fan. Too high and it hits the seat!

This is why there is a bend in the tube.

The front shim was made the same way, but the front floorboard is level. No taper here! I made it 9/16 in thick, but I think I might try a thinner shim.

More later!


Friday, March 26, 2010

Control Stick Torque Tube

What a busy week - work picked up and the kids had a big baseball tournament - so it felt good to get back to the hangar today.

Since the stick pedestal castings arrived, the next thing that had to be fabricated was the torque tube. No original Curtiss drawing exists for the torque tube, so Doc Hood hand drew one for me from scratch and I was grateful.

The torque tube has a 12 in. radius bend in the middle so the tube clears the rear rudder bar. It's a pretty stout bar - 1 1/8 in OD and .095 thickness. That's pretty thick!

The first step was to make templates for the inside and outside of the bend. I also transferred the Doc Hood drawing onto a piece of plywood.

Now the fun part. I've tried a lot of ways to bend tubing - filling the tube with sand, using a die roller etc. But Paul Dougherty told me he bends all his tubing with heat alone and I found his method works best...if you are patient!

Here is what I mean.

Heat the top of the bend until three or four inches are nice and red. Then heat the bottom of the bend the same way. Do not heat anything else.

See, heating the tubing makes the metal pliable. You want the top of the bend to stretch and the bottom of the bend to compress. You want to keep the sides cool (relatively speaking) so the tube will not kink! It really works.

Anyway, Keep alternating the torch between the top and the bottom while pulling on the end of the tube.

Here you can see the results of the process. Notice how the tube started to curve nicely. The left side has been worked and I was using the template as a guide. You want to "drag the hot spot" or simply heat an area until it bends a little then move further down the line.

See the heat marks extend the entire length of the curve. "Drag the hot spot". It takes some time to work this. Don't be in a hurry. Heat a little area at a time.

Here is the 12 in. radius when compared to the plywood template. At the end of the radius, the tube bends the other way. I bent the right side back to level using the same method above, but before I had time to bend the other end, it was time to pick up the kids at the bus stop. I'll post a picture of it next time.

John Gaertner sent me pictures of the ailerons. As with the wings, his workmanship is first class.

Chet Peek sent me these pictures last week. They are not Jennies, but since I really like seeing pictures from the Barnstorming era, I thought you might like to see them too. Anyway, Chet wrote:

These pictures show the Hisso powered J-1 Standards that were sent to Call Field in Wichita Falls TX and used for photographic training. They had to get to 7000 feet to get photographic coverage, and the Jenny wouldn't make it
But here is some mystery. The order, placed in December 1917 states they were Standard JR-1's, but they are clearly not. They have the regular J-1 gear and have a Hisso, not a 6-cylinder A-5 Hall-Scott which was used on the JR-1's.
So here we have a beautifully designed Hisso powered J-1 which did well according to the few pilot reports I could find. And yet they continued with the somewhat troublesome Hall-Scott A-7a.

Chet is writing a book about the Standard J1. I hope he saves me an advanced copy.

Also came across this old picture of three Jennies at Kelly Field. I forgot where the picture came from, but it's a neat photo and I wanted you to see it too.

More later


Thursday, March 18, 2010

Todays progress

Now that the tank was in the right place, the end of the fuel shutoff rod could be made. First, the rod was cut to length just short of the valve. Then, the end was flattened with a hammer.

Then, two pieces of flat stock was cut, drilled and welded in place.

Now you can get a better picture of the entire assembly.

Here's the assembly after blasting and primer paint.

The whole shutoff assembly.

Made the fuel tank hold down brackets too. They were cut out of flat stock, about 3/4 in wide and bent using an 1 1/4 X 1 1/2 in steel block (the same size as the longeron). Remember that the turnbuckle end goes between the flanges, so you need to leave a 3/16 in gap. Plus, the flange is bent a few degrees, so don't drill it until you have the proper bend angle (experience learned by building the second one!)

See how it goes?

Here is the other side. This one is easier to make because the flanges touch together.

Got out the wire wrapping jig and made the strap.

Here is how it goes. There will be a felt pad underneath, but I will leave that until final assembly.

Glen came by the hangar and I put him to work making the upper tail strut fitting. He cut the .065 stock on the bandsaw and finished it with the grinder and file.

Filed smooth.

Here is the fitting in place.

And the lower original brace below the new fitting.

A package arrived from John Gaertner today containing the throttles and stick pedestal castings. He did marvelous work and I can't wait to install the pieces next week.

Busy weekend coming up - kids have baseball tournaments and our museum is having a benefit dinner on Saturday night, so I'll probably get back to work on the Jenny around Monday.

Till then, enjoy


Friday, March 12, 2010

Fuel Tank Cradle, Throttle, Starting Mag

Hello again - I've been flying a lot of trips lately. It seems work has gotten busy which is a good thing considering I'm employed in the aviation.

While flying around, I had an opportunity to stop by Fantasy of Flight in Polk City, FL and have a look at their uncovered Jenny project. I took a bunch of measurements and I returned home ready to remake the fuel tank cradles.

Glen Marsh met me at the hangar and we started bending the new strips of .090 steel.

We used the usual system of steel blocks and a good hammer.

This time, we put the new straps in place, leveled the lower section and made a mark where the tab will be bent.

At this mark, the tab was bent.

Then everything was drilled.

To show you the difference, here is a picture of the new JN4D cradle on the left and the JN4D2 on the right.

Even better, here are the two new cradles.

Here I'm giving it a trial fit below.

Much better! Notice there are only three slats.

One of the things I measured at the Fantasy of Flight Jenny was the measurement between the top of the firewall and the top of the fuel tank. It was 1 1/2 inches. I set our fuel tank to this dimension.

During the week, I got a nice e-mail from John Cole from Peoria , AZ. He sent me a picture of the Jenny model he had built.

John wrote:

I refinished an old Proctor 1/6th scale r/c Jenny, and decided to jazz it up a bit. I painted it to resemble one of the a/c purchased by Heddon Tackle Co. of Dowagiac, MI. They used it to fly into large fishing meets, delivering their lures, giving rides, etc. I used the old Renwal plastic kit for reference, and the model certainly gets some attention (laughs) at the meets!!

Take care, and keep up the incredible work on your airplane.

Thanks, John for sharing pictures of your beautiful model.

I had been giving a lot of thought to the Hisso engine lately and one of the things I thought long and hard about was starting the engine. With a 9 1/2 ft. propeller and the E2 version of the Hisso (high compression), hand propping the engine was looking like a challenge. In the old Hisso manual, I read about a starting magneto that they used back then. With the engine on a compression stroke, spinning this crank would cause the spark plug to fire and the engine to start. No hand propping required. Man, I thought, I gotta have one of those!

But where was I going to find one?

Fellow old aeroplane restorer Jim Hammond just happened to have a spare and he was kind enough to send it to me. I can't wait to see how it works. Thanks, Jim!

John Gaertner sent me pictures of his progress. He finished the throttle castings and throttle arms.

And also shaped the wing tip bow on the final remaining wing.

That's it for now. More soon.