Tuesday, 30 August 2011

21 foot wing, 18 foot garage.

I knew the wing would not fit easily in my garage, basic math told me that, but now that it is in 3 dimension form, it becomes alarmingly clear just how much room it takes up.
I continued to build the the top wing ribs through early July, and also started to work on the spar center splice joints. I had not been looking forward to these splice joints, as for an 1 1/2 thick spar, at a 15-1 ratio splice, the joint would be 22 inches long. This is a large splice.
So I built a router jig to cut the splices in each board.
I got the idea for this jig and the method of cutting from Dave Binkley, who is building a beautiful 1932 Monocoupe 110, the restoration of which is nicely decribed on his site;
Dave does beautiful work, and it was really handy to see how he had worked out this splice method.
(thanks again Dave)
I spent a day building up the router jig, and testing it with a short length of spar.
The main points to note,
The spar has to be held completely secure, if there is any movement, it will affect the taper joint, and this is especially true as it gets to the end, which decreases to a feather edge.
It is very important to limit each pass cut depth to less than a 1/16th of an inch, any more and the router will be working too hard,and could move the spar or dig in.
Make sure via a solid base, the router cannot tip.
Go slow, methodically, and do not cut with the gyroscopic rotation. (huh?)
this means that as the router bit turns, do not try to cut into the rotation, this will let the bit wander and run away, you should always be pulling the router against the rotation. This is probably easier to do than explain, but it is pretty important.
I left the spar 3 inches long in at the end of the jig, to allow me to screw it down, then as each pass is made the jig cuts deeper into the end, and eventually, after about 30-40 passes, you have a 22 inch perfect taper.
I have a 1/2 inch shaft Makita router, which is a pretty heavy duty unit, I would not want to try this splice with a 1/4 inch shaft router, as I am not sure it would be rigid enough, I guess it would work, but it would probably require a great many more passes, as the cut depth would be so slight, as well a 1/2 inch straight bit only requires 50% as many passes to cover the same width and length.
So after a few rather nerve wracking hours, I had completed the 4 required splices to create two main spars.
and as usual, my capable assistant, displaying the appropriate safety equipment, was with me every step of the way.
Once the splices were complete, next step is to glue them, not an overly complex step, but I did make sure that when I made up the joint, first I spread normal mixed T88 on both surfaces, let this soak in for about 10 minutes, and then mixed micro balloons into the remaining epoxy and re spread over the joint surfaces, I did this to ensure that the glue would stay in the joint and not migrate out under pressure.
(note the seemingly never ending process of rib construction in the background)
Once both spars had been joined at the center, I marked out all rib locations, and also cut the various plywood doublers which are at fitting attach points.
When I was building the ribs, I had to keep adjusting my rib fixtures to allow for the various thickness plywood which the ribs must fit over, and in some cases different thickness at the front and rear spar points, this all takes time, but it worked out well, and each rib fit nicely over the planned plywood plates.
Now that all ribs are done, all 72 of them, I can honestly say I have had enough of building ribs!! I worked out I have about 800 hours into the ribs alone, this covers the parts cutting, and preparation, the various jigs and assembly fixtures, and all of the assembly. I think I could have built an RV6 start to finish in about the same time as the ribs have taken.
Here is a simple little tool I made to check the spar centers as I went along. The Super Solution spars sit at 20 inches from front to back, at the center, so to accurately measure this, I lathe turned two short sections of 3/16th stainless rod to a point at one end, and threaded the other ends with a 1032 die.
I drilled a section of aluminum angle at exactly 20 inch centers, and it becomes a handy center checking tool. This replaces the expensive trammel sets which can be used here as well, but this costs next to nothing.
By using a longer aluminum section and routing a channel at one end, this can be used as an adjustable trammel set to true the drag / anti drag wire bays.

I had to halt production for a family holiday in Thailand, we left mid July, and spend 3 weeks in Hua Hin, south of Bangkok, a beautiful beach resort.
The holiday was fantastic! but I was back home in Dubai early August for work, and production resumed. My family stayed in Thailand an additional 3 weeks, so I had the house, and more importantly, the garage to myself, which made for some very productive days.

I wanted to complete all of the wing woodwork, which meant I had to laminate the two tip bows, build the three tapered ribs, and also the leading edge boards.
After the lower wing tip bow disasters, I got smart, and asked David Oviatt to please send "full size" templates of the tip bow, and the three tapered end ribs. He had already worked all of this out in CAD, so he was able to produce and send these drawings.
What an incredible difference, no guessing, I was able to take the full size drawings, build a table for the tip bow (the wing was now taking up the entire bench) and in short order build two perfect tip bows, both identical, and the corrrect shape, the first time!
It is amazing to see how effective CAD can be, when an expert such as David uses it.
also by modifying my existing full size rib jigs, I was able to build the smaller versions of the truss and compression ribs.
With all of the structural woodwork now complete, I decided to take the wings outside for a group photo, the first time they have left the garage, and been outside.

The next step will now be to make all of the metal fittings for the top wings, and there are alot! over 50 separate parts, so much cutting, drilling and welding to go. I am a little more realistic after the lower wings, and I expect the metal parts will take me about a month and a half.
I will be able to now accurately measure the drag / anti drag wires, as there is such little room for error, and order them from Russ, at Vintage Aero in New Zealand. They will take a couple months to produce.
Then it is a a matter of assembling all together, at this point none of the ribs are glued in the top wing, as the spars still need drilling once the fittings are made.
However, I can now see the end in sight for the wings, and I am already looking forward to switching gears onto the fuselage, the tubing for which has been patiently hanging on the wall for a year now.

Wednesday, 22 June 2011

Starting the Top Wing

With the lower wings pretty much complete,
(they still need the leading edges, but I will leave them off for now) it is time to start the Top wing, as it is a bit behind schedule.
The Top wing is 21 feet long, and the chord is 42" but as it has no ailerons, no taper, and no dihedral, it is a pretty simple structure.

I still need to build the lower wing ailerons, but I am waiting for the aluminum spars to be bent and shipped, they are coming from Canada as I cannot find anyone in Dubai who has an accurate brake over 6 feet long.

As the second lower wing went together so much easier than the first, I will build a complete kit for the top wing first, and pre fit everything. This should make the final assembly very quick. On the lower wings, I worked out all the details on the first wing, and then built a "kit" for the second wing.

I have started by making all the parts for the ribs. There are a total of 40 ribs, 30 Truss ribs, 8 compression and two plywood.

as with the lower wings, the ribs are a quite time consuming to build, each rib has 14 parts, 10 spruce and 4 routed plywood. They require a total of 10 cutting, bending, and assembly fixtures, and are assembled with no nails.

I can build 1 -1 1/2 per day, so thats my July mapped out.

I am also starting to laminate and then scarf the top wing spars. The spars have a 15-1 scarf at the center, so I shall have to build a new scarfing jig for them, more on this later.

My shop (garage) building space has recently been cut in half, as we live in Dubai, UAE, and it gets pretty hot here in the summer, I have a deal with my wife;
Once outside temperatures reach 45 degrees C ( 113 F!) then she can keep her truck in the garage,

well it has reached 45 degrees. and next month it will be 50 (122 F)

Thats why all of my benches and tool cabinets are on wheels.
Unfortunately it does not start to cool down here until Mid September, so I have to watch I do not inadvertently stick a spar through her windshield.
Another issue with the temperatures is I keep the garage at a comforatble 20C with AC, but every time the door opens the temps soar to ambient, and it takes a while to cool down again.
It is quite a "dry" heat, so no real issues with humidity in the summer, but it does get extremely humid in the fall, and I would worry about unprotected wood.
(but by this time I shall have once again banished the truck to the driveway)

Anyway, this will not really impact on production, but it does illustrate one more of the "issues" building in this part of the world.
Even the walk from the house to the garage, about 30 feet, is quite miserable in these temperatures.

Ironically, even on the hottest days here, my primary mode of transport  lives outside.
The seat gets pretty hot.

Friday, 20 May 2011

Matty laird had a sense of humor

Once all the ribs had been glued in place, it was time to pre varnish the wing sections which would receive fittings, wires, etc, and at this point the varnish really brings out the beauty of the spruce and the mahogany plywood.
I imagine the only way that every drag anti drag wire could hit a rib diagonal or upright was by careful pre planning in the design phase.

And they do.

Well that is not exactly correct, as they do miss ribs # 6 and 9, but only barely. And since brushing up against most of the ribs was not good enough, the wires actually go directly through the uprights in ribs
# 3,8, and 13.
Matty must be having a quiet chuckle over this.
Of course the wires contacting the ribs in so many places creates issues. Every location needs to be braced, then the cut out determined and shaped to allow the wires a clear run. The uprights were braced either side, and then the hole drilled directly through the center upright.

I had the wires made up by a company in new Zealand, Vintage Aero, run by Russ Ward. Russ specializes in recreating wires as they made them back in the 30`s and even earlier. The wires are beautiful, and very different from a modern stainless drag wire. Each steel wire has 1 LH and 1 RH rolled thread, a square section for tightening and they have a hot dipped finish. The wires are really nice, and they arrived in the exact lengths as ordered, which was great as there is no room for error.
It is nice to have another source for wires beyond Bruntons. Russ also does streamline wires.

Onward with the lower right hand wing, once all the ribs were glued in place, next step was corner blocking, and putting the spar strips in place top and bottom.

The metal fittings had arrived back from the powder coaters, so I was able to bolt various fitting in with the correct hardware. The Aileron hinges are placed in position at this point, but I do not want to attach them until the ailerons are completed to ensure everything lines up perfectly.
Once all of the wires and fittings were installed, next was the wing tip bow installation, (version 4) which went pretty smoothly, using the measure 50 times, cut once technique. I could not even think about having to make wingtip bows version 5!
Sometimes the biggest challenge is working out effective clamping solutions, and when dealing with tapered and curved surfaces this can be quite entertaining, with clamps on clamps. One can never have enough clamps, either in number or variety.
My main concern was shaping the bow, as it is not a symetrical radius, due the low chord line of the wing. This means the bow is constantly changing radius, from a 2 inch height at the leading edge, to less than 3/4 inch at the trailing edge, but multiple passes with an air angle grinder, and finishing up with a long block sander  produced the desired results.

The Lower right hand wing is now essentially complete, still to be installed are the various plywood sheeting, at the tip, root and along the leading edge, it is all cut to size, but I shall wait until the lower left hand wing is completed to the same stage, as I would like to have this wing as a reference.
The next lower wing will go much quicker, as while I have been building the right hand wing, I have also made all parts for the left hand wing. The spars are shaped, and drilled, the ribs are ready to glue in place, all steel fittings are complete and pre located, the wires are on hand, and the wingtip bow is ready. Below is the left hand wing in kit form, ready to assemble.

Wingtip bows version 1,2,3,4.....

I built the first wingtip bow a few months back, and based the shape on a template I made from the EAA replica.
It turns out a tracing made on a fabric wing, on an aircraft mounted in a museum display, at a 15 degree angle, with the paper taped in place with low tack tape, standing on a ladder, is not the most accurate means of getting an exact shape.
who knew.

I was not happy with the first pair of bows, the laminating and glue up was fine, but the shape just did not look right, so I stared at it for a month or so, hoping it would magically transform into the correct shape,
It did'nt.
but I knew I would end up making another set, so eventually I started version 2.
Only to find out I had reset the jig blocks with an incorrect raduis of about an inch.
another 16 strips of spruce, lots of T88 glue, a few days, and I had a good start on a harp frame.

This was not going well.

Version 3, and by now about 30 board feet of perfect spar grade spruce later, and this one looked really bad, no need to wait a month, I knew this one was way off the desired and rather distinctive Laird shape.
I was getting desperate, they were getting worse.
From left to right Versions 1,2, 3 and the final correct bow. 
OK, it was time to resort to technology, a request made to David, (the computer guy) and in no time a full size template arrived, beautifully printed, and it was the exact shape. David is an incredibly talented fellow, and he tends to work in minute dimensions, and while I try very hard to build the parts to his exacting dimensions, eg; 30.987, I may inadvertently make the part 31.0, seeing as it is wood!
(and David has actually dropped his standards, he used to work to the 5th decimal place).

For a fourth time, I set the 25 or so jig blocks up, planed another 14 strips of spruce, soaked them in hot water and ammonia, and carefully laminated two bows up. (I was getting pretty good at this) I knew right away that the shape was correct, but it is amazing when they are placed beside versions 1,2, and 3 just how far off I was each time.
I apologize to all that beautiful old growth spruce which was needlessly sacrificed in my quest to make the perfect wing tip bow, but as anyone who had played hockey knows, you may play every game in the regular season, but not everyone gets ice time in the playoffs!.
So, once again, it is amazing how much an 80 year old airplane project can benefit from modern computer technology.
now all I had to do was mount and shape them.

Monday, 2 May 2011

Finally... we reach the beginning

I have managed to catch up with the current status of the project, as of May 1, 2011.

The lower RH wing now has the ribs glued in place, and ready to varnish, all plywood doublers glued in place.
The lower LH wing is ready to glue, all parts made and fit, holes drilled, and ribs final fit.
The steel fittings are all powder coated and ready for re-assembly, and the aileron hinges are finish welded and waiting for final assembly.
The wing tip bows are complete and require final shaping, taper and sanding, then will be attached to the now tapered spars.
The new hardware to assemble the lower wings is now all in hand.
The lower wing drag / anti drag wires should be shipped from NZ within a week.
The leading edge spars, for the LH and RH wings are now laminated and await final profiling.
The wing trailing edge material is now in hand.
The aileron rib template material is now in hand and the rib profiles have been determined.

In other news, all fuselage 4130 tubing is in hand and awaiting assembly.
I hope to get a start on the fuselage assembly by late May.

The landing gear, both main gear and tailwheel assembly, are under assembly in Australia with a highly competent and experienced friend.
(more on this later)

The Tail surfaces are also currently underway, in Canada.
(more on this later)

The trim assembly machining is about to start.

The majority of the original instruments have been purchased and are in hand.

I shall be updating this as and when I have new photos and progress to report. This will certainly NOT be  on a daily or even a weekly basis, but it should be fairly regular.

I am happy to respond to comments, or questions, and I am always grateful for advice.

Should anyone have items, parts, or components which they think are relevent to the project, I would enjoy hearing from them.
My email address is shown in my profile.

If you have managed to get this far, thanks, and hopefully you have found it interesting.

Firewall Forward

While most of the subjects so far have been centered around the wings, and they represent most of the racers visual progress to date, I have still been collecting bits behind the scenes.

From my very good friend Mark Blok, I purchased the engine for the Super Solution some time back.
(ignore the colour please)
The engine was removed from a DHC 2 Beaver, having reached its time to OH, and is currently stored with LA Aero, awaiting rebuild. As there are calenderic items on the engine, (and it`s a very expensive process) this will have to wait until it is imminently required, and I think we are still a while away from that!
Mark also included a Hamilton Standard 2D30 Constant Speed propeller, which is in need of a full rebuild but it is a valuable addition to the project. While I intend to run a ground adjustable propeller similar to the one shown below (the hubs are the correct 5406 hubs, but the blades are 4350's. They are beautiful but not rated for the 450HP 985). I think it may be wise to initially run the CS, due the potential adjustment issues with the fixed Hamilton Standard propeller. There would of course also be C of G issues as the CS unit is much heavier than the ground adjustable propeller.

(I am sure the yellow case looked great in the Beaver, but for the Super Solution, we will revert to a more standard and subdued P&W grey)

By the way, should anyone have a set of suitable HS "toothpick" blades, rebuilt or acceptable for OH, please let me know.

Shown above is the Hamilton Standard ground adjustable propeller.This is comprised of a set of 4350 blades and a 5406 30 spline hub. I have also managed to locate a couple of spare hubs.
These hubs are getting very rare these days so a couple of spares are a welcome addition, in particular if the main chosen hub should fail its inspection. ( luckily, they all look perfect )

I have also recently located and purchased a complete set of R985 baffles which are getting very hard to locate, as well as many engine fittings, hoses, and components.
I now have an original engine mount ring, and the engine mount attach brackets.
But, perhaps the luckiest find so far, has been a set of NOS cowling skins, formed rings, and all brackets, which will allow a custom cowl to be built up exactly as the original was, using pre formed cowl sections. These have not been built for 60+ years, and are extremely rare.
I think the project is in good shape FWF, with the major components all on hand.

Close is easy, Identical takes longer

Next were the aileron hinges, 3 of which are required on each lower wing.
I was not looking forward to making these, as I knew that there could be no allowance for error, and they would have to be identical.
The ailerons are mounted on the lower wings only, and they are attached via a round tube spar to 3 hinges bolted to the rear spar.
The ailerons are of a mixed construction, with a steel tube front spar, steel plate and tube hinges, steel rib attach fittings, and aluminum ribs, rear spar, leading and trailing edges.
They are almost full span on the lower wings.
And they seem to have be very suseptible to potential binding, maybe that is why the original never fluttered. :)
The hinged section seemed like the natural place to start, and as they must all be identical, another assembly fixture was required.

This is the first fixture I built, it allows the first part of the aileron hinge to be welded up. Shown behind are the tubes all cut and shaped to size to fit inthe fixture and mate to the larger spar hinge tube.
I then made a separate fixture to sand the forward tube ends to mate to the U shaped bracket accurately.
Once the first part is welded and match sanded, I then needed to make the U shaped sections which fit over the spars, and there is NO room for error with these. each must be an exact press fit, which is harder than it sounds when you are working with wood to metal, but in the end (after about 15 which did not work as well) I ended up with 6 exact U shaped sections, bent to the correct dimensions and drilled.
The lower wing spars have a 7 degree upper taper and a 3 degree lower taper, which must be bent correctly in the fittings, then they are bent to flat after the spar to match the attach block. (otherwise the bolt head and nut would not be parallel to the fitting)
I then built this fixture to weld the U brackets to the spar attach tubes accurately. After I tried to weld the first one, I had to change this, and substitute a steel spar section for the wooden one shown due to the wood burning. It took almost a week to have the steel spar section machined up by a shop to the finish spar dimensions.
It is now a completely useless block of rather expensive spar shaped steel.

The final hinges are all indentical, and once attached to the real lower spars should hopefully line up accurately with the front aileron spar.
To build the 6 hinges three separate fixtures had to be built. It took much longer to make the fixtures than the actual hinges.

Making wood do un-natural things

I knew at some point soon, I would need a set of lower wing tip bows, as these set the final spar lengths, so I took a break from metal fittings to build the two lower wing bows.

I started by ripping 14 strips of spruce, 2 inch by 1/8th" by 7 feet.
I wanted the finish bow width to be 1" which would match the leading edge spar, and also matched the amount I had left off the ribs to the leading edge point.
So 7 strips inclusive of the glue would make up 1" in width.

I next needed a fixture to laminate the bows, and I knew from experience you cannot have enough clamps or clamping points when making a bow.
Shown above is the jig blocks screwed in place, around the wing tip bow shape. I made a template of the EAA replica lower wing tip, and then matched this to my pre measured spar locations, so I knew all would (should) match up.

Also shown are the spruce strips. They have already been soaked in a bathtub of boiling water with ammonia added.
(ammonia softens the fibers of the wood and allows it to easily be clamped in place)
The thoroughly soaked strips are then clamped onto the bow fixture with NO glue and allowed to dry.
Once they dry the clamps are removed and the various strips will have taken on the required final shape.
Next glue is applied to all the strips, and they are re assembled and clamped in place. The more glue wiped away when wet will make the final clean up much easier. Care must be taken to not glue the strips to the fixture!
and the finished laminated wing tip bow. Once the bow is dry, it is removed from the fixture and cleaned up by running it through the table saw. The LH and RH bows are the same at this point, as they still will need to be cut down and trimmed to final shape, then tapered and rounded.
and with the wing tip bow shapes determined, the spars can then be trimmed and tapered to final shape.

The fittings are in there somewhere

I had the various thickness 4130 steel sheets, and I had a pretty good idea what the fittings should look like.
But turning the sheets into this:
is not so easy, and takes an amazing amount of time.

The main reference for the fittings was photographs and the actual wing structure. I knew kind of what they should look like, but turning photos into practical fittings is an altogether different exercise.
There were no dimensioned drawings of the various fittings.

The above fitting is the RH I strut attach point, landing wire, and drag wire attach fitting. This assembly is comprised of 5 separate steel fittings.
there is an opposite assembly on the LH lower wing.

The first issue with the various fittings is deteriming the actual dimensions. I started by making them all in cardboard, then dry fitting the ribs where fittings would be attached, and then by using dummy wires, and measuring angles, I could determine whether the specific fitting would work as drawn.
The next step is to determine the fitting material thickness, some of which were shown in various documentation, some not, but there were enough shown in various laird drawings to allow the rest to be accurately determined.
The original fittings were 1025 mild steel, but 4130 carbon steel is used instead as it has superior strength  for the same thickness.
If the original thickness was no longer available, the next larger size was used, ie; if the original was .059, .063 would be used.
All fittings requiring welding are TIG welded.
For some assemblies, fixtures were required, as below, the lower wing root attach fitting weld fixture.

Each of these assemblies is made up of three parts, a bent U section made of .063, and two plates made of .100 4130 sheet.
They are match drilled and then edge welded on the assembly fixture. The front spar assembly is about 15% larger than the rear spar assembly.

 and this is where the two assemblies will end up, at the spar roots.

Some of the other wing fittings include the rear spar I strut attach point
and the various drag / anti drag wire attach fittings. Each lower wing has 19 separate metal fittings

this set does not include the aileron fittings, which are a separate assembly all together.
Once all the lower wing fittings had been cut, drilled, bent, filed and welded, they were placed in the relative positions on the spars, and dry fit. Once it was determined they were in the correct locations, and did what they were supposed to, the spars were marked and drilled.
Before the spars could be drilled the plywood had to be cut and dry fit to the spars, both to determine the exact thickness of the fittings, and also to assure the holes would all line up.
*also shown are the fittings I welded up to attach the spars securely to a fixed root point for future assembly.
Once all spar holes were final drilled, and it was determined all fittings would work, they were taken off, cleaned up, and powder coated a gloss black.
(It appears you could have wing fittings in any colour in the 1930`s as long as it was black)

With all wing fittings in place, and the ribs in position, the various drag / anti drag wire lengths were measured and the wires ordered.
The wires are being produced with each a LH and RH rolled thread. The inner and mid bays will have 1/4" diameter wires, and the outer bays are 3/16th wires. All wires are 4130 steel, with a hot dipped finish to replicate the original finish 1025 of mild steel wires.
The wires are being produced in New Zealand, and should be delivered by mid May 2011.

The LH and RH lower wing fittings took a total of 5 months to build from initial cardboard mockups to finish power coat, and all were ready for final assembly by the beginning of April 2011.
Unfortunately there would have been no time savings by drawing the fittings in CAD and having them laser cut, as each fitting went through many versions before the final dimensions were determined.
During the fitting build process, the wings were dry assembled and taken apart at least 8 times.