Thursday, August 29, 2013

All About the Engine

The Engine:
The engine supplied with the project is a Continental W-670 radial of 220 HP. An excellent choice since the U.S. built thousands of these during WWII and parts are still plentiful (most parts, that is), as well as the knowledge base on the workings of the engine.
This particular engine was sold to Jim Friedline with the promise that it was a "low-time" engine, but upon opening the oil sump, I discovered a piece of metal about 1/8" X 3/4" which is pretty significant for a piece of metal banging around inside an airplane engine. This would explain why a low-time engine was removed from an airplane in the first place. As it turned out, the metal is from a ball bearing cage that came from the rear main engine bearing. This is not an uncommon failure on this engine, as I learned, and an STC was granted years ago for a roller bearing replacement. That's on my buy list—very expensive. Fortunately, the pieces were small and light weight, so there was almost no damage. The metal was confined to the sump and bottom half of the engine and was obviously found at an early stage.

 Many more such pieces were scavenged as the tear-down progressed, but the only noticeable damage was to the skirts of the aluminum pistons, and that was limited to some shallow dings that don't seem too bad. This, I'll have to research further. New pistons are very expensive for this engine, but I'll replace anything that is out of limits or damaged.

With Jim's help, I removed the crankshaft, the master rod and separated the two crankshaft counterweights.

The Bearing Less Cage (in pieces)

The rods have been separated from the master rod and all those parts cleaned, and bead-blasted. The steel parts were dropped off at Graham Aircraft Engines on Tuesday, Aug. 21st to be magnafluxed.

I took the cylinders to Jim's and removed the valves with the help of his handy-dandy valve spring compressor tool.

 In fact, I used two because I broke the first one using a long cheater bar and way too much force. But he had another one, of course (I owe him one). Jim measured all seven cylinder bores and gave me the good news that they all checked standard (within new tolerance). Not bad...maybe this was a lower time engine than we thought. Lucky for me.

Now a word about this engine:  this project was supposed to be a Travel Air E4000. In fact, Jim paid quite a sum for paper work on an E4000 to make this a standard certificate airplane. When I learned that it was originally intended to be an experimental (replica) airplane, I think Jim felt bad about it. He shouldn't have, because the price was right and the workmanship nearly perfect.

He offered me this engine that he had in storage in exchange for the two old crappy engines that came with the project when he bought it. One of them was good for nothing but a boat anchor and the other was marginal. This engine, although it had the bearing failure, is a gem. It will be an easy and (relatively) inexpensive overhaul. This is one of the joys of doing this sort of thing—dealing with good people like Jim Friedline. And make no mistake, he is one of the best there is.
As for the engine case, I dropped the three pieces off at Frank's Heads and Engine Service in Griffin, GA. This is a great automotive engine shop. He runs two type cleaning vats, one for steel parts and one for softer metals like aluminum, etc. He ran my three case sections through his high pressure/high temp vat for $97. Not bad. They came out clean as a whistle. I should have removed the engine data plate, because the chemicals messed it up. The letters are still there, but the coating is gone. Not to worry, good ol' Jim had a stack of them.

Next will be the cylinders. They'll need to be thoroughly cleaned, but I'm not sure I want to bead blast them—too many oil galleries that could be plugged. I may just get Frank to vat them, too. I'm working against the clock here trying to get any engine work done while Jim still has his shop-full-of-parts. He is selling out, lock, stock, and barrel to another engine builder. All this stuff will be gone shortly, so we are getting everything done that we can now. Building the engine up should not be a problem since I don't think he is selling all his tools, but he is the best source for any parts that I'll need, and he has graciously offered me any I require.
Now it's trip,time again. The down side of being an airline pilot and working on an airplane is that whenever you start making good progress, you have to drop everything and go off to Paris or Brussels. Darn the luck.
The real problem is remembering where I left off.

Home from Paris on Monday, Aug 26 and going to make a quick inventory of where I am and what to do next.

Tuesday, August 27, 2013

Some Early Fitting

With two welded steel fuselages, hangar space is at a premium. I really need to get the one I'm going to use up on wheels so it can be maneuvered around easily. The experimental (non-original) fuselage is the one I'll be using since I believe it is the strongest one and easiest to build up. The original type would need a whole set of bracing wires plus I'd have to figure out how to attach all the wood bulkheads and stringers. The other one was built with all that in mind. There are little tabs welded onto the frame to attach all these items, plus framing for inspection plates, framing for a little baggage compartment, etc. It seems Mr. Rowe thought of just about everything. He has obviously done this before. Anyway, his improved fuselage is the one I'll be using, so earlier I had it sandblasted and primed with Poly Fiber Epoxy Primer. This was done by Wayne McKimie at his blasting facility near Brookbridge Aerodrome. He does good work at reasonable prices, and he's a pilot to boot, so he understands what is being done.

 Also earlier, I did a preliminary fitting of the landing gear legs and braces. The fit was a bit tight so, on the advice of Bill Hammond, I heated certain areas of the gear with a torch to get a slight expansion without ruining the temper of the 4130 steel. This involves heating to just barely a dull red and no more. This heating is done while the gear is in place which provides the force needed to "persuade" it into the desired position. With this done, the gear legs were primed as well, the required bolts purchased and the gear legs attached. With the possibility of rotation about each bolt, I am using drilled bolts and castellated nuts to be safetied with cotter pins. The point of contact between the main gear legs and the drag brace required a 5/8" bolt, which is not easy to find. Aircraft Spruce normally carries AN and NAS bolts only up to 1/2" diameter. So (again) on advice of Mr. Hammond, I bushed the 5/8" holes down to 1/2" and used 1/2" AN bolts. With all the gear legs and braces fitting, it's time for the next problem. I was unable to find wheel bearings and axle nuts anywhere in any of the boxes that came with the project. I could have sworn there was a set in a box somewhere, but they're not here now. Bill Hammond to the rescue again: he supplied me with a bag of bearings and nuts until such time as an order could be placed for these items. Another problem: In the bag were a set of wheel bearings which fit perfectly. One axle nut was perfect, but the other one slipped over the stub axle and was obviously too big. A quick flight in the RV-4 over to Peachtree City and a visit to Aircraft Spruce got me a set of MS21025-24 nuts. When I tried to thread them on the axle I discovered they were the same size as the one that was too big. What's up with this? The sizes for axle nuts follow 1/4" increments, like 1", 1 1/4", 1 1/2", etc. But stuck in the middle of all these is this little -23 which is a 7/16-16 thread. Go figger. A search for this size delivered nothing. I tried everything with Google Search to no avail. Finally, one parts supplier in Seattle was able to locate a pair of these odd little guys in California for FIFTY BUCKS EACH! No thanks. I put out the word...somebody has got to have some of these in a junk box somewhere. Harold Spivey called me with a lead...Talon Air in Dickinson, Texas has everything. A call to them got me a set for $20 each. Now that's more like it. Nice people, too.

 The wheels are the old 30X5 wheels—1920s style. These can be a bit fragile, especially when presented with a side load. These have been modified to make them more robust. Rivets around the periphery of the wheel have been replaced with Hi-Loc fasteners, also known as Jo Bolts. There are other changes as well, but suffice to say, they are much stronger than original. Tires and tubes are hard to come by for these wheels, but the project came with a set of two slick 30X5 tires from Coker Tire. These are the people that supply tires to the classic car crowd. They have everything. Problem is, they emboss "For Display Only" right on the tire. They don't want to accept any liability with aircraft use, which is understandable. This will have to be ground off. Next is the brakes. I have a set of Bendix brakes and I am wondering if I'll have the same problem Bill had with his, that is, grabbing at low speed. This is not good. I've done some reading about "self-energizing" brakes without much understanding. Automobile drum brakes have a primary and secondary shoe, with the primary being slightly shorter and mounted forward. I can't see any difference in mine. Bill Hammond solved his problem by replacing his with Red Line brakes. Not sure if I'll have the same problem, but would love to correct any known problems now before it is flying. Any suggestions?

So now the fuselage is on its wheels and can be scooted around the hangar as needed to make room. This will also make it easier to make bulkheads and fit them. That will happen as soon as I can get this engine work and varnishing done. Oh yeah, also have to finish the lower wing tips and roots. Gotta make a list for next week.

Getting Started

The active part of the project started with correcting some problems with the wings. The original builder made the ribs with correct cross-sectional dimensions, but they are "truss type" ribs instead of the plywood web type that was standard for Travel Air. The only Travel Air wing that utilized that type rib construction was the "speed wing" which had a thinner cross-section than the standard, but this wasn't one of those. Also, he added an extra nose rib between each main rib and made the spars from solid laminated spruce.

A problem became apparent when tracing the path of bracing wires within the wing. There was interference with rib components at several locations in each wing panel. This was solved by cutting the offending rib "leg" and gluing and nailing a bypass leg with the addition of small gussets. (A picture is worth a thousand words here.)

 This provides plenty of strength and only a minuscule increase in weight. There were only a few places where this interference occurred, so it was not a huge problem—I was just unsure about my fix, and wanted it to be strong. After a consultation with Bill Hammond, I felt much better. He has forgotten more about this stuff than I'll ever know, and he allowed as how it was a proper fix.

The other thing was that all four wings were assembled with steel fittings installed that connect the upper wings to the center section and lower wings to the fuselage, connect struts from wing to wing, and external bracing wires. Not a problem in and of itself, but the wood has not yet been varnished. In order to get full coverage, the fittings would have to be removed, the wood underneath varnished and the fittings re-installed. The fittings are held in place with AN5 bolts and nylon lock nuts. The nuts would have to be replaced since the nylon type can only be used once reliably.

The process of varnishing wings, especially truss-ribbed wings, is labor intensive and I've got lots to do, so I hired the son of a friend to help. Mitchell Mordas has been very helpful in tasks like these, and he is getting an eagerly anticipated education on airplane building. He was especially helpful when it came to tearing down the engine, which was done concurrently with the woodworking. This is a another part of the project that would take a lot of time.
I started the varnishing/rib altering/fitting removal/replacement in early summer and it will be finished in a week or two as of August 23rd.

Friday, August 2, 2013

Time to Inventory and Start Building!!

With the Morgan project complete and a suitable rest period following, the time to start another airplane has come. I am excited! The Travel Air is one of the most significant designs in the early years of aviation. This company broke many records and impressed many important people of the day with this design. There were others to follow, like the Cabin Class Travel Airs (flown by Delta, by the way), not to mention the "Mystery Ship" which took many trophies in air races in the hands of legends like Jimmy Doolittle and Doug Davis. I have always had a soft spot in my heart for this airplane. Now there is a chance to actually own and fly one. Unbelievable.
Wangs...Lots of Wangs
During the inventory of this project, which has been through several owners, it is apparent that almost everything needed to complete the basic airplane has been included. By whom, I will never know, but there's lots of stuff in lots of boxes.
Brand New Sensenich Propeller!
Great Old 30X5 Wheels

Truck Load of Parts
Lots O' Stuff