1911 Curtiss Ely Project Progress

ulpilot · 22 October 2009, 02:21 PM

Had to adjust the gap in the rudder on mine to fit the stab and rudder tiller. Also I glued in bushings where the hinge bolt passed through the tiller and stab. Over kill for a static display aircraft, but the mechanic in me couldn't let that go!

Thought about going with the upholsery nails and reed rib battens. Had lots of offers of help from volunteers, till I explained that operation. Funny how they suddenly found more pressing matters!

So I went with Polyfiber instead.

N44VY · 22 October 2009, 03:33 PM

Thanks, Vet. I had planned to insert a bronze bushing in the hinge post pivot as well. Visions of the bolt augering out a big hole, followed by rudder slap and a cracking sound! I admit I am on the fence about nailing the rush strips to the ribs. I plan to rib stitch the Poly-Fiber to the ribs, but had tossed around the idea of button head tacks holding down the rush. I don't worry about the time involved in driving all those nails - but I do worry about the fact that each one of those hundreds of nails removes strength from the ribs as it splits the wood's grain.

So you used the large gusset in the center of the stab. spar where the rudder post goes thru? Looks like I'll have to re-configure my rudder hinge opening. Regards, Bob C.

ulpilot · 23 October 2009, 03:04 AM

Yes, I used the gusset blocks. Maybe a thin (.015-.020) steel plate top and bottom of the blocks to add more support to the ends of the bushing would be a good idea. Also remember to add a thin washer or 2 between the tiller and stab to reduce the bearing surface area. and add a note to lube that point every few hours. I imagine the tail takes a beating with the prop blast.

The ribs may not split with the tacks, since they are laminated from 8 layers of spruce. If you have any spares, why not do a test?

N44VY · 23 October 2009, 04:04 AM

Vet: I like the idea of supporting the bronze bushing insert. I'm thinking this: Build up the center of the stab spar as in the Schultz plans with blocking and thin plywood gussets as shown. Then, drill thru the gussets and spar for the bushing insert. Then, using a properly sized large Forstner Bit, drill the gussets, top and bottom, just enough to flush fit and epoxy the fender washers. Make the inner ID of the fender washer match the OD of the bushing and make the bushing long enough to fit flush with the gusset surfaces. That should capture the fender washers firmly in the gusset and also provide additional support to the top and bottom edges of the bushing.

I'll try this on a mock-up - if it looks good - OK. Otherwise, I will look at the thin steel plate idea of yours. I just think I can get a thicker bushing support surface with the fender washers while saving some weight over the steel plate caps. Good idea or not?

Which brings up something else I have encountered. In the Ely-Curtiss configuration used to fly onto the USS Pennsylvania, the forward elevator was reconfigured from the Schultz example. The Ely bird used a single bamboo brace running via a wheel fork from the nosewheel to a hinge located at the bottom center of the elevator spar. The outer elevator hinge points were attached to the outriggers, as normally done, and wire cable ran down from the outer hinge points to the nosewheel axle via metal tabs at each end. These cables replaced the two bamboo struts on earlier Pushers without the center bamboo strut. Long winded description just to get to my point: The photos of this single strut configuration show the outer hinge points at the tips of the elevator, at the outrigger junction, as in the Schultz drawings. The photos also show, in my view, that the central hinge is below the spar. That means there is about a 1" difference in the hinge alignment axis from the end pivot points to the center point. The result would be that the spar would have to flex as the elevator was moved up and down. Am I interpreting the photos correctly, or do you have a different slant?

Having said all of the above on the hinge pivot points, I went ahead and modified the two at the ends of the spars by adding tabs of sufficient length to drop the hinge axis down and in line with the center hinge. Not by the photos, but it does line everything up. None of this is irreversible. If someone out there has a definitive, authentic or more elegant solution, please scan your cranial data banks and old Pusher pics to see if you get the intuitive flash which solves all. Thanks to all! Bob C.

N44VY · 23 October 2009, 04:18 AM

This is a small photo, but it does show the center bamboo strut configuration used in the USS Pennsylvania landing. Casey's book, "Curtiss, the Hammondsport Years" has very defined photos of this change, if you are fortunate enough to have that reference. Bob C.

ulpilot · 24 October 2009, 04:19 AM

Sure does look like the center hinge point is below the elevator. On page 96 is a picture of the Triad and that looks like the elevator is bowed, which would happen if the center hinge was below the outer hinge points.

You have the better solution. Not accurate, but way more practicle for a frequent flyer.

I'll check my other research material and let you know if I find anything different.

N44VY · 5 November 2009, 12:51 AM

Vet and Gang:

Couple of questions about the elevators and horizontal stabilizer:

1. Replicas I've seen have the hinges on the top, mostly, but one has them on the bottom of the mating spars. Good practice says place the hinges on top of the spars, but I wonder if there is an overwhelming reason not to? Also, I have seen three sets of hinges used per elevator and I've seen 4 hinge sets on one plane. The Schultz drawings are not clear. Looking at the elevator design and rib placement, I suspect three hinge sets were originally used. Place the center hinge in line with the center rib that carries the elevator control arm to strengthen the stab and elevator spars at that flex-load point. Then place the other two hinge sets mid-way between the two outer ribs for a symmetrical match. With the 4 hinge set up, there is no hinge at the elevator control arm. Anyone have it on good authority how many were used and where?

2. The Schultz drawings show both the elevator and stab spars as flat cut boards with slightly rounded edges. This causes clearance issues between the elevator spar and the stab spar with the hinges placed on top or bottom. Let's go with the best choice and put the hinges on top for this example. If I want the elevator to move up and down without hitting the stab spar, I have to move the elevator aft to open up a rather large gap, otherwise the spar binds on the stab spar at the lower-mid point of down elevator throw. I am not happy with the large gap mainly because it reduces the hinge bearing surface on the spars, and secondarily because it is a high drag problem. It seems to me that an elegant solution would be to slightly bevel the elevator spars to allow more down elevator movement and thus enable me to close the gap. Was that what Curtiss did, or am I missing something with the Schultz drawings?

As always, I thank you for any input you wish to add. Bob C.

ulpilot · 5 November 2009, 03:18 AM

Bob,

I used 3 hinges per side. Some really nice ones I picked up at the Woodcrafters Store. They were brass, unlike the original steel. But after a coat of paint the look just like the originals Stanley Trunk hinges.

Like you I was confused on the spars, as I could not find any good photo's of that area. So I went with hinges on top, and beveling the elevator spar.

When in doubt, remember, 99.9% of the people that will see the finished plane will think it is great. I'll ignore the other .1% unless they can show me their 100% perfect replica.

N44VY · 5 November 2009, 04:54 AM

Vet and the Gang:

Three on top and bevel the elevator spar is just the ticket. Thanks. I found hinges as you described - fairly heavy brass with extruded pin tangs vice the hardware store rolled tang variety. The pins appear to be steel or stainless - shiny instead of brass colored - but I will still punch them out and use something like small clevis pins to lock things together.

As you know, I am building this Ely-Curtiss Model D for the US Navy Centennial of Naval Aviation Celebrations in 2011. So far the planning committee has announced over 20 events and airshows all over the US ofA, beginning in March, 2011 and ending in November. There are plans for about an additional 10 shows which are in works. When I look over the scheduling dates, I see at least 7 shows that I can potentially fly to, participate in and then fly to the next in time to appear. Based on distances and 50 mph groundspeed, it will take a little under 100 flight hours, over 75 enroute stops, and will entail crossing the Appalachians twice. This covers events spanning six months. If I can't find a flyable route over the mountains, I'll lose half the shows. We'll have a van chase car, two to three pilots to swap off and van drivers as we can get volunteers. I expect the van to beat the Pusher to each gas stop, so we should always have a ground crew standing by.

The thing I need to build is a caster system for the nose wheel, but I haven't thought this through yet. Replica flyers would taxi straight, stop, pick up the nose wheel to turn, taxi some more, pick and turn some more, then strap in and take off (or forget to strap in and take off!). I'd like to have a small caster system that I could land, stop, slide in place and taxi to the ramp using rudder blast and minimal braking to steer. For take off, I'd caster to the runway, remove the caster, clip it to the rails and launch. Got any design ideas for this? Any suggestions appreciated!

You know, though, that this is just dreaming right now. I may wreck it during flight tests, for goodness sakes. Or we may end up in the trees over Ernie Gann's "Hell Stretch". Still - fliers were born to dream big! Bob C.

ulpilot · 6 November 2009, 03:49 AM

I wish this thread was on the replica board instead of buried here on the pioneer board. There would be a lot more views and comments there.

Castoring nose wheel system. Need to be as simple as possible, yet sturdy enough to handle the less than perfect taxiways at some airports. Here are some random thoughts.

Why not start with a tailwheel off a Cub, Champ or such. Benefit of having both locking and castoring modes. Would make taxing in a straight line, or in a crosswind a little easier. Add a couple of clip on pushrods from the rudder pedals an you add steering capability.

Maybe weld up a modifed A frame with the castor at the apex. This would place the castor ahead of the nose wheel. The base legs would have some tubing welded on that is split lengthwise to fit over the forks of the nose wheel. Use the other half of the split tube as the clamp. Weld on a couple of ears on the upper and lower clamps for bolts and wingnuts to hold the assembly in place. Line the clamps with felt or leather to protect the paint on the forks. Just might work!

I flew several cross country flights in ultralights over the years. Never had a chase crew, but wished I did once. 2 biggest concerns were fuel availability ( 2 stroke oil/mogas mix ), and miday thermals. My Cub rides turbulence like a Mercedes car, compared to how my ultralight handled it!

I'll have to find a way to make a few of those shows. Sounds like way to much fun!