1910 AVRO Triplane Build
11-16-2014, 05:14 AM
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Part 10 - Bottom Wing
So it's time for the wings. I must admit that I have been anxious about tackling the wings from the very inception of this project. They are long, thin, probably fragile and there are three of them. Could I come up with a design that made the build reasonably simple? I did the design for all three wings and had all the parts laser cut all in the same order, I built the bottom wing first. It is the shortest (5 feet) and the simplest. The middle and upper wings still await but I am satisfied with the results of the bottom wing.
First, about the laser cutting. There are lots of sources for cutters and it is a very popular topic on this forum. For this project, I have used Laser Design Services, run by the colorful character "LimeyBob." I have nothing but high praises for his work and service. I provided the DXF files directly from CAD. They included separate layers for cutting and text. Within days my order was shipped. (About 20 4"x24" sheets!) It arrived well packed and undamaged. Bob inadvertently let out two sheets. Without any hassle he made it right and immediately sent out the missing sheets. The quality of the wood was very good and the cuts were precise. A nice touch was that Bob added the gaps in the cut lines so that all the parts remained with the sheets and did not fall out. I didn't put that into the drawings. All the parts snapped out clean and easily. I highly recommend him. I will have him cut all my parts.
OK. On to the build....
I think the secret to making the building of these wings simple is to build the wing upside down and with the use of a tab that I added to the rib design. The wing is under cambered so that makes traditional building difficult. With the the tabs and building the wing upside down, the process became more typical.
First step was to make the long spar and leading and trailing edges from shorter pieces. Normally great care has to be taken with splicing in structural members but this is not your typical plane. In that era, the strength of the wings came more from bracing than in the structural integrity of the wing itself. The spar did not have the typical role. The wing does not rely on the rigidity of the spar to keep in flat. That's not to say that slicing can be done sloppily but it is not important to stagger the splices or have extremely long joints.
After the long bit were made, I doubled a few of the basswood ribs to bring them to 1/4" thick. These ribs will have the strut brackets screwed into them so they need to be stronger and wider than just balsa ribs.
Next came the laying out of the ribs on the plans. No magic here. The spar was laid in the rib notches without gluing. Once everything was in place and true, drops of thin CA were added to tack it all together.
The trailing edge is quite thin and flexible so I used thick CA and glued the trailing edge down on one end rib. When that was set, I just went from one end to the other, flexing the trailing edge so I could apply CA to each rib and set the trailing edge in place. It went very quickly.
The leading edge was applied like the spar. It was put in place without gluing and then thin CA was applied. To add some strength and prevent bowing of the end balsa ribs, basswood cap ribs were added to each end. It makes for a nice clean finish.
Another feature I added to the design was a little nib at the front of each rib. That provided a tiny seat for the leading edge. Once everything set, the wing was removed from the table and thick CA was added to all joints. The balsa tabs were removed and sanded flush with the rib profile along with the leading edge nibs. I left the basswood tabs on for now. I'm not sure that was necessary but I can still lay the wing upside down and keeping it stable.
The middle wing is next.
So it's time for the wings. I must admit that I have been anxious about tackling the wings from the very inception of this project. They are long, thin, probably fragile and there are three of them. Could I come up with a design that made the build reasonably simple? I did the design for all three wings and had all the parts laser cut all in the same order, I built the bottom wing first. It is the shortest (5 feet) and the simplest. The middle and upper wings still await but I am satisfied with the results of the bottom wing.
First, about the laser cutting. There are lots of sources for cutters and it is a very popular topic on this forum. For this project, I have used Laser Design Services, run by the colorful character "LimeyBob." I have nothing but high praises for his work and service. I provided the DXF files directly from CAD. They included separate layers for cutting and text. Within days my order was shipped. (About 20 4"x24" sheets!) It arrived well packed and undamaged. Bob inadvertently let out two sheets. Without any hassle he made it right and immediately sent out the missing sheets. The quality of the wood was very good and the cuts were precise. A nice touch was that Bob added the gaps in the cut lines so that all the parts remained with the sheets and did not fall out. I didn't put that into the drawings. All the parts snapped out clean and easily. I highly recommend him. I will have him cut all my parts.
OK. On to the build....
I think the secret to making the building of these wings simple is to build the wing upside down and with the use of a tab that I added to the rib design. The wing is under cambered so that makes traditional building difficult. With the the tabs and building the wing upside down, the process became more typical.
First step was to make the long spar and leading and trailing edges from shorter pieces. Normally great care has to be taken with splicing in structural members but this is not your typical plane. In that era, the strength of the wings came more from bracing than in the structural integrity of the wing itself. The spar did not have the typical role. The wing does not rely on the rigidity of the spar to keep in flat. That's not to say that slicing can be done sloppily but it is not important to stagger the splices or have extremely long joints.
After the long bit were made, I doubled a few of the basswood ribs to bring them to 1/4" thick. These ribs will have the strut brackets screwed into them so they need to be stronger and wider than just balsa ribs.
Next came the laying out of the ribs on the plans. No magic here. The spar was laid in the rib notches without gluing. Once everything was in place and true, drops of thin CA were added to tack it all together.
The trailing edge is quite thin and flexible so I used thick CA and glued the trailing edge down on one end rib. When that was set, I just went from one end to the other, flexing the trailing edge so I could apply CA to each rib and set the trailing edge in place. It went very quickly.
The leading edge was applied like the spar. It was put in place without gluing and then thin CA was applied. To add some strength and prevent bowing of the end balsa ribs, basswood cap ribs were added to each end. It makes for a nice clean finish.
Another feature I added to the design was a little nib at the front of each rib. That provided a tiny seat for the leading edge. Once everything set, the wing was removed from the table and thick CA was added to all joints. The balsa tabs were removed and sanded flush with the rib profile along with the leading edge nibs. I left the basswood tabs on for now. I'm not sure that was necessary but I can still lay the wing upside down and keeping it stable.
The middle wing is next.
Last edited by Chevelle; 11-16-2014 at 05:26 AM.
11-22-2014, 07:12 AM
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Time Out
So I had this dream the other night but here's a little background first. As you may recall from when I started this project, my fascination with this plane goes all the way back to the movie in 1966. Of course then, once it left the theaters, there was little chance of seeing it again except for the rare showing on television. It wasn't until 1978 or so that I ever saw the plane again. This time it was in the form of an R/N model at an R/C expo in Los Angeles. I bought both the Curtiss Pusher and the AVRO Triplane kit. (How prophetic since I eventually did the Curtiss Hudson Flier and now the AVRO.)
Anyway, I built both kits. For all my professional career, the AVRO hung in my office. That kept it out of harms way from the eventual three kids and other sources of catastrophe that befell all of my other stick and tissue models after all these year. Today, it is certainly showing its age. The doped tissue is very dry and brittle and a few glue joints have come undone but it is still here.
Back to the dream... In the dream, my R/N model suffered some pretty extensive damage. The wings were broken on one side and dangling. The rear part of the fuse was cracked in a few places too.
That got me to thinking. (Not a good sign. It strikes fear into my wife when I say that but she has been a great sport through all of my hair brained ideas.) I certainly have more information about this plane than anyone short of the Shuttleworth folks. I can certainly bang out a smaller version of the plane without all the scale detail folderol of the bigger version. An modern version of the R/N kit.
So that's what I did. (Or am doing.) I have designed a 1/12 scale version of the AVRO Triplane. It will be laser cut and very easy to assemble. No rigging required. Should go together very quickly. The design will show a version with and without ailerons for those that might want to fly the damned thing. Servo, receiver, batteries, ESC, and other such items will be a real bear to locate. There isn't much room but I am sure some will figure it out.
I have no idea how many I will make. I'll make a few bucks on each but I won't be in it for the income. It's just a fun project and it would be great to see others get into this plane without the craziness of the 1/4 scale version.
I'm not taking orders or anything but I would like to know if any of you are interested. I know that there will be at least 10 of so from my club that will want to build one. That will give me an idea of how many to make in a run and that will help me determine the cost of the wood and laser cutting.
Hey, why should I have all the fun!
So I had this dream the other night but here's a little background first. As you may recall from when I started this project, my fascination with this plane goes all the way back to the movie in 1966. Of course then, once it left the theaters, there was little chance of seeing it again except for the rare showing on television. It wasn't until 1978 or so that I ever saw the plane again. This time it was in the form of an R/N model at an R/C expo in Los Angeles. I bought both the Curtiss Pusher and the AVRO Triplane kit. (How prophetic since I eventually did the Curtiss Hudson Flier and now the AVRO.)
Anyway, I built both kits. For all my professional career, the AVRO hung in my office. That kept it out of harms way from the eventual three kids and other sources of catastrophe that befell all of my other stick and tissue models after all these year. Today, it is certainly showing its age. The doped tissue is very dry and brittle and a few glue joints have come undone but it is still here.
Back to the dream... In the dream, my R/N model suffered some pretty extensive damage. The wings were broken on one side and dangling. The rear part of the fuse was cracked in a few places too.
That got me to thinking. (Not a good sign. It strikes fear into my wife when I say that but she has been a great sport through all of my hair brained ideas.) I certainly have more information about this plane than anyone short of the Shuttleworth folks. I can certainly bang out a smaller version of the plane without all the scale detail folderol of the bigger version. An modern version of the R/N kit.
So that's what I did. (Or am doing.) I have designed a 1/12 scale version of the AVRO Triplane. It will be laser cut and very easy to assemble. No rigging required. Should go together very quickly. The design will show a version with and without ailerons for those that might want to fly the damned thing. Servo, receiver, batteries, ESC, and other such items will be a real bear to locate. There isn't much room but I am sure some will figure it out.
I have no idea how many I will make. I'll make a few bucks on each but I won't be in it for the income. It's just a fun project and it would be great to see others get into this plane without the craziness of the 1/4 scale version.
I'm not taking orders or anything but I would like to know if any of you are interested. I know that there will be at least 10 of so from my club that will want to build one. That will give me an idea of how many to make in a run and that will help me determine the cost of the wood and laser cutting.
Hey, why should I have all the fun!
Last edited by Chevelle; 11-22-2014 at 07:14 AM.
12-08-2014, 06:31 AM
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Part 11 - Middle (and Top) Wing
Ok. Back to our regularly scheduled program (although I did finish a set of plans for a 1/8 and 1/12 version.)
The middle and top wing have hinges in them to provide lower stresses for the wing warping. (The full scale had them too.) I first just sandwiched the spar sections to keep everything straight. I used a Dremel to make a groove across the two sections of the spar where the hinge will go. After some epoxy, I have a hinged spar.
My building table is eight feet long but I felt it better not build an eight foot wing on an eight foot table. I made the splices for the leading edge, trailing edge and spar but did not join them.
I changed the building process from when I did the bottom wing. Before, I laid the ribs out, added the spar, then the leading and trailing edges. It actually goes better if the leading edge is done first. All the ribs seat nice and firmly against the leading edge. Then the spar slips quite easily in the notch. (I am having a set of 1/12 parts laser cut and I have snugged up the tolerances so things will fit a bit tighter.)
After building one half of the wing, I shifted it down and partly off the table so I could build the other half. The leading edge was added first then the ribs where glued in. The spar was spliced next and then laid in the rib notches and glued. Finally the trailing edge was spliced in and glued to the tips of the ribs.
The trailing edge extensions where added along with quadrupled basswood ribs. These will be used to fasten the wing to the fuselage.
These are just pictures of the middle wing but I have also built the top wing.
Ok. Back to our regularly scheduled program (although I did finish a set of plans for a 1/8 and 1/12 version.)
The middle and top wing have hinges in them to provide lower stresses for the wing warping. (The full scale had them too.) I first just sandwiched the spar sections to keep everything straight. I used a Dremel to make a groove across the two sections of the spar where the hinge will go. After some epoxy, I have a hinged spar.
My building table is eight feet long but I felt it better not build an eight foot wing on an eight foot table. I made the splices for the leading edge, trailing edge and spar but did not join them.
I changed the building process from when I did the bottom wing. Before, I laid the ribs out, added the spar, then the leading and trailing edges. It actually goes better if the leading edge is done first. All the ribs seat nice and firmly against the leading edge. Then the spar slips quite easily in the notch. (I am having a set of 1/12 parts laser cut and I have snugged up the tolerances so things will fit a bit tighter.)
After building one half of the wing, I shifted it down and partly off the table so I could build the other half. The leading edge was added first then the ribs where glued in. The spar was spliced next and then laid in the rib notches and glued. Finally the trailing edge was spliced in and glued to the tips of the ribs.
The trailing edge extensions where added along with quadrupled basswood ribs. These will be used to fasten the wing to the fuselage.
These are just pictures of the middle wing but I have also built the top wing.
Last edited by Chevelle; 12-08-2014 at 10:43 AM.
12-03-2016, 05:34 AM
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Part 12 - Finishing the Wings
Maybe if I just start typing, no one will notice how much time has passed since my last post.
Lot's of progress has been made but nothing posted. It's time to catch up!
For this post, here are two videos showing the covering and painting of the wings. They are covered with neutral SolarTex. Rib stitching was added. (Now that was tedious!) I sprayed my DR1 but I really didn't want to go through the hassle of setting up a temporary spray booth. I hand brushed the Hudson Flier and that came out OK but those wings were made from separate panels. I wasn't sure it will look very good on these one piece wings. This time, at the suggestion from my wife, I tried rolling. It was great!
The paint is Benjamin Moore "Cancun Sand" eggshell. The Hudson Flier was a more yellow color and then the shifting from the polyurethane took it more yellow. Still acceptable but more than I was going for. The Cancun Sand is a warm off-white. I expect the urethane to shift it towards the yellow again to get it where I want it, a dingy off-white. So far, so good.
For the next one, I might go with a semi-gloss. The eggshell is pretty flat but the gloss comes up with the clear satin polyurethane. Starting with the semi-gloss may should bring that up further but ideally not too far.
More to come...
https://www.youtube.com/watch?v=Xigp6Hl1UvM https://www.youtube.com/watch?v=DKPABZV5Ogk
Maybe if I just start typing, no one will notice how much time has passed since my last post.
Lot's of progress has been made but nothing posted. It's time to catch up!
For this post, here are two videos showing the covering and painting of the wings. They are covered with neutral SolarTex. Rib stitching was added. (Now that was tedious!) I sprayed my DR1 but I really didn't want to go through the hassle of setting up a temporary spray booth. I hand brushed the Hudson Flier and that came out OK but those wings were made from separate panels. I wasn't sure it will look very good on these one piece wings. This time, at the suggestion from my wife, I tried rolling. It was great!
The paint is Benjamin Moore "Cancun Sand" eggshell. The Hudson Flier was a more yellow color and then the shifting from the polyurethane took it more yellow. Still acceptable but more than I was going for. The Cancun Sand is a warm off-white. I expect the urethane to shift it towards the yellow again to get it where I want it, a dingy off-white. So far, so good.
For the next one, I might go with a semi-gloss. The eggshell is pretty flat but the gloss comes up with the clear satin polyurethane. Starting with the semi-gloss may should bring that up further but ideally not too far.
More to come...
https://www.youtube.com/watch?v=Xigp6Hl1UvM https://www.youtube.com/watch?v=DKPABZV5Ogk
