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Old Aug 30, 2010, 11:37 AM
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United States, WI, Fond du Lac
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Build Log
Lockheed Vega series. Plans and an invitation

Ever since reading Revolution in the Sky: The Lockheed's of Aviation's Golden Age by Richard Sanders Allen, I thought it would be cool to model the entire Vega series of aircraft. The Vega series (Vega, Air Express, Sirius, Altair, and Orion) were all built with the same monocoque fuselage and essentially the same wing. (The ill fated Explorers used a larger wing.) Reconfiguring the parts lead to the various types.

Most aviation enthusiasts are aware of Amelia Earhart, Wiley Post, and the Lindberghs' exploits in the Vega but I was surprised to read what a leap in performance the Vega represented. For the period between 1927 and 1933 the Vega and its variants set or held virtually every speed, altitude, and distance record. (A Vega still holds the altitude record for diesel-powered aircraft!) Considering it was designed as a passenger plane, the accomplishments are all the more remarkable.

I plan to build at least two variants: a high wing Vega or Air Express from the beginning of the Vega line and an low wing Altair or Orion which can be thought of as ultimate development of the type. The invitation is to anyone else out there to build one of the other variants with the goal of getting an example of every variant built. Anyone want to participate?

I’ve drawn up plans at 1/10 scale and will post them after I’ve test built from them. While I plan to use the same materials and methods I used for my Dinah build http://www.rcgroups.com/forums/showthread.php?t=1240702. I hope to see other materials and techniques used.

Specs:
WS: 53”
Length: 34”
Wing Area: 420 in^2
Motor: Rctimer 3630 900kv
Battery: 2200 mAh
AUW <40 OZ.
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Last edited by pmullen503; Aug 30, 2010 at 11:44 AM. Reason: insert link
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Old Aug 30, 2010, 11:54 AM
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United States, WI, Fond du Lac
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Drawings

I'm working with the excellent Wylam drawings I got from http://plans.aerofred.com/.
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Old Aug 30, 2010, 12:33 PM
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Plans

Here's where I'll start posting plans. These are PDF's created from my CorelDraw originals. It's always a good idea to check the accuracy of your printouts. File conversions and printer issues can cause errors. I'll try to put dimensions on the files so you can check your printouts. Let me know if there are problems.
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Last edited by pmullen503; Sep 22, 2010 at 11:58 AM. Reason: added wing
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Old Aug 30, 2010, 01:30 PM
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United States, WI, Fond du Lac
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Fuselage

Like the original, I'm going to use a formed monocoque fuselage. If you check out my Dinah thread (http://www.rcgroups.com/forums/showthread.php?t=1240702) you can see the methods I intend to use.

I really like this method. The result is lighter, stronger, stiffer, faster and cheaper than anything else I've tried for making a fuselage. The form takes a while to make but once you have it you can make many shells from it. Only one form is required for the Vega; the right and left halves are are identical.

First, Cut the side profile from 1/2 plywood. I glued the form outline printout to the plywood and sawed one side close to the line and used a disk sander to get a nice smooth curve. I left slightly more wood on the second side. To get both sides matched, I marked a centerline on a piece of paper, traced my reference side, flipped the plywood over and traced the other side next to the reference side. Any where the two lines diverged I sanded the second side. Then I repeated the tracing. After four tries, the two lines converged so I knew both sides where the same.

Next I cut out the foam blocks. I had to glue up blocks to get them thick enough for the center sections. I cut the blocks to fit between the former locations on the form outline printout. I glued the form template printout to cardboard (cereal box weight) and cut out the templates on the outer line. I used the cardboard templates to rough cut the blocks with a hot wire. (It worked better than I would have thought.)

Once all the foam blocks were roughed out, I glued them to the plywood. I left a gap between the blocks so I could slide the templates back in to check my progress while sanding the form to shape. I kept sanding until I got close to the inner line (about 1/16" away). Then all I worried about was getting a smooth curve and getting the upper and lower quadrants to match. It took me about 30 minutes to get the form sanded. My favorite tool for rough shaping is open mesh abrasive used to smooth drywall mud (see photo 4).

After the form was shaped, I realized I needed a former for the back of the cockpit for the open cockpit variants (Air Express, Sirius, and Altair) so I made the cut with the hot wire at the appropriate place, slid some cardstock into the slot and traced the former. One of the really nice things about this method for scratch building is that you don't need CAD. With just a few cross sections from a 3-view you can shape the fuselage form and make a cut where you want add a former, trace it, and your good to go! I traced all of the other former stations while I was at it.

I covered the form with epoxy and 6oz. cloth. It's not required if you are careful during the heating step. I've pulled 3 fuselages from the Dinah form and it's fine. But I plan to pull multiple copies from this one and the same form is used for both halves so it will be subjected to more heating cycles.

Total time to get this point was just under 6 hours.
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Old Aug 31, 2010, 12:45 PM
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Fuselage

The Vega line used a formed plywood fuselage (except for the DL's built in Detroit). Three layers wood veneer were layed up inside the concrete mold with casein glue and then the lid with a shaped rubber bladder was lowered onto the form and bolted in place. The bladder was inflated to press the veneers against the mold and left to dry. The shells were then glued and tacked to a wooden frame. The finished shells were only about 1/4" thick! The resulting fuselage was strong and light and completely clear of obstructions inside. (first two pictures below)

Time to mold my fuselage. For those who have never tried this method, the principle is to heat the foam to the point where the walls of the millions of bubbles that make up the foam soften but not melt. The foam can then assume a new shape that it will maintain when cooled. The gas in each bubble expands when warmed and unless contained, the foam will expand and eventually the bubbles will pop. The shaped mold functions as the male mold and tape functions as the female mold to contain the outward expansion.

The tape is a key component of the system and I've tried several types of packing tape. Regular packing tape works fine for shapes without severe compound curves. For shapes with compound curves, the best tape to use is PVC packing tape. http://www.uline.com/Product/Detail/...n-Sealing-Tape is the stuff I use. The PVC backing shrinks more than the commonly available polyester tape and you get fewer wrinkles near the edges of shell.

Start by cutting a piece of foam (I'm using 1/4" fan fold insulation) to the approximate size. I wrapped a piece of newspaper around the mold and cut off the excess to determine the shape. Leave an extra inch or two around the edges.

Cover one side with strips of tape, overlapping 1/4" to 3/8". Try to get it flat, without wrinkles. (I applied mine right over the film thats on one side of the FFF).

Using a broom stick, preshape the foam but rolling the untaped side. Start on something like carpet and move to softer surfaces and more pressure to create a curved surface with no kinks. This cold forming makes it easier to tape to the form. I use a window screen spline tool to score the edges of the foam. Makes it easier to get many small kinks rather than a few large ones.

Then you tape it to the form. I start with a few pieces of tape to hold it in place. Then work your way around taping the foam snugly to the form. You'll get wrinkles around the edges because of the compound curves. Try to spread them around evenly, making many small kinks around the edges rather than a few large folds. (I use a window screen spline tool to score the edges of the foam. Makes it easier to get many small kinks).

You want the foam in contact with the form. Feel around the outside and if an area is not in contact, re-tape it. Use only enough tape tension to get the foam to stay in contact with the form. Too much tension will leave a wrinkle in the finished shell that has to be filled.
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Old Aug 31, 2010, 01:49 PM
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Oven

You need to get the foam to about 200F to 210F for the foam to soften. It's possible to do this with careful use of a heat gun. If you get a spot too hot it'll melt and the foam will collapse. Not hot enough and the foam won't reform. It's hard to tell when you've reached the right point. I went ahead and built myself an oven to bake the whole thing at once. My oven cost me nothing because I made it from parts I had lying around.

The first thing I tried was a couple cardboard boxes taped together with a hole in one end for my heat gun. It worked but the heat was uneven. Eventually, I came up with the oven in the photo. It's box made from 1" foil faced foam insulation. I ripped 5 pieces of 16" x 48" foam (cut one to make the ends) and taped them together with packing tape. (When I'm done with it, I cut the tape and stack up the pieces for storage) Inside is a shelf made from galvanized sheet metal supported on some 2x4 legs. There are gaps between the metal shelf at the ends and around the sides to let air flow. The metal shelf functions to support the form and distribute the heat more evenly.

The heater is a small ceramic space heater. I got it free at the local dump, probably there because the fan was making noise. A little oil fixed that. Space heaters have an over-temperature device that breaks the circuit if it gets too hot. The cutoff temp is too low for forming foam so I bypassed it. The thermostat also has to be bypassed because it's not designed to regulate at the relatively high temperature I need. I regulate the temperature by turning the heater on and off with a power strip while watching the temperature on my multi-meter.

I've run this setup for many hours now and aside from oiling the worn out fan motor, it's holding up fine. There's a photo and a drawing below.
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Last edited by pmullen503; Sep 03, 2010 at 08:53 AM.
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Old Aug 31, 2010, 02:24 PM
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Here's a finished shell. The form was placed inside the oven and the temperature was brought up to around 90C (194F). I hold it there for five minutes or so to let everything warm up. Then I bring the temperature up to 100C (212F), turn off the heater and let it drop back to about 97C (206 F). Then I repeat the cycle. At the beginning the heater runs about 1/3 of the time. Towards the end it drops to about 1/5.

For FFF and 6mm Depron, 15 minutes is adequate. For Hobby Lobby 1/4" foam board 10 minutes works well. For Dollar Tree foam keep the temp below 95C and limit heating to 10 minutes.

Be careful not to bake for too long or too hot. The form is made from the same stuff you are forming! The plywood backer insulates the form as does the FFF itself but if you cook it too long or too hot the form can be damaged. (Thats also why I wrap FFF all the way around the ends even though they'll eventually be cut off). My fiberglassed form will be fine. I must have pulled 20 half nacelles from my Dinah form (also glassed) with no damage. Bare foam is another matter..........

When finished, take it out and let it cool for few minutes. Remove the tape holding the shell to the form, not the tape covering the foam. If the shell stays tight to the form it was heated enough. If it springs away slightly when the tape is removed, it wasn't heated hot enough and/or long enough. (You can re-tape the shell to the form and heat it again if needed.) When it's right it will conform perfectly to the mold. Mine even has the imprint of the fiberglass cloth used to cover the form on the inner surface! I leave the outer tape on to protect the foam until the fuse is assembled and I'm ready to cover the outside.

The weight of one half shell is 32g. (BTW, for comparison, FFF weighs the same as 1/16" contest balsa). I takes me about an hour to tape, cold form, tape to the form, and bake one half shell.
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Old Aug 31, 2010, 09:59 PM
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Australia, WA, Ellenbrook
Joined Feb 2008
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oh i do like the look of that sirius, it has that GeeBee-Ylook about it! great subjects mate.
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Old Sep 01, 2010, 11:07 AM
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Originally Posted by trumps View Post
oh i do like the look of that sirius, it has that GeeBee-Ylook about it! great subjects mate.
Yes the Sirius is a handsome plane but for my low wing version I'm leaning toward an Altair. Specifically, Kingsford Smith's Lady Southern Cross which you can see in post #1 not only do I like the paint scheme but I have another indirect connection to the plane that you, as an Aussie, might appreciate.

Several years ago I visited Turkey and was deeply moved by their respectful, almost reverent observance of ANZAC day. There's nothing remotely like it in America. A commemoration of the bravery of the soldiers who died trying to invade your country? It's something that's stayed with me.....

Smith's plane was originally delivered with the name ANZAC but the Australian government required the name be removed.
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Old Sep 01, 2010, 11:37 AM
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Here's some photos of how I mark the shells. Because the internal structure is added to the shell, opposite of a typical balsa build, you have to accurately lay out the former locations and centerline on the shell.

First, after trimming the edge of the shell, I mark the former locations using the form. (You can see how tightly the shell conforms except at the very tip; theres a limit to how severe a curve you can do.)

Next I used my traced former templates to mark the center lines and the former locations. I used a pin to transfer the centerline to the outside.

I taped together the shells to check the fit and it was good. I'm always amazed how strong and stiff the shells are once taped together with no internal structure at all.

Normally, at this point I'd assemble and fit the internal structure but I noticed a problem. I was thinking about how to lay out the passenger window locations and realized the radio, wing and landing gear mounts would all be visible through the windows. I will also need to paint the inside before I join the fuselage halves because it will be mostly inaccessible later. That sent me back to the drawing board to come up with a better looking solution.

Important Note: Generally, it's better to glass the inside before trimming and marking the shells; you'll get a cleaner edge to join thats easier to tweak if you have too. If you get resin on the edge its tough to sand later.
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Last edited by pmullen503; Sep 05, 2010 at 07:45 PM. Reason: Add note
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Old Sep 01, 2010, 05:43 PM
What's 3D?
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Australia, WA, Ellenbrook
Joined Feb 2008
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Nice story mate, it is funny how an ilconcieved, and disasterous battle for both sides not far short of 100 years ago has formed a rather unique bond and friendship between our countries, not something that I recall hearing about between many other former foes! The ANZAC day service at Gallipoli has sort of turned into a bit of a right of passage for many Aussies, to pay our respects to both sides, and thank for their sacrifice. It was really a pivotal moment for us and many would say the birth of our nation! I just hope that is not ruined by a few drunken yobbos which does seem to be what happens these days.
This is shaping into a fantastic and very informative build, as i have no experiance in building with foam, thanks for sharing it with us.

Cheers
Craig
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Old Sep 02, 2010, 04:10 AM
classicaero
oxford,MI
Joined Jul 2004
891 Posts
Nice project, nice work!
Why not vacuum form the fuselage sides? You can control the weight by using a different thickness, say 020 to 080 ?
Allen
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Old Sep 02, 2010, 10:08 AM
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Originally Posted by trumps View Post
Nice story mate, it is funny how an ilconcieved, and disasterous battle for both sides not far short of 100 years ago has formed a rather unique bond and friendship between our countries, not something that I recall hearing about between many other former foes! The ANZAC day service at Gallipoli has sort of turned into a bit of a right of passage for many Aussies, to pay our respects to both sides, and thank for their sacrifice. It was really a pivotal moment for us and many would say the birth of our nation! I just hope that is not ruined by a few drunken yobbos which does seem to be what happens these days.
This is shaping into a fantastic and very informative build, as i have no experiance in building with foam, thanks for sharing it with us.

Cheers
Craig
The story of Gallipoli is inspiring. Should be required reading. A fine example of how former foes can reconcile.
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Old Sep 02, 2010, 10:35 AM
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Originally Posted by classicaero View Post
Nice project, nice work!
Why not vacuum form the fuselage sides? You can control the weight by using a different thickness, say 020 to 080 ?
Allen
If you mean vacuforming using plastic, the skin would certainly have adequate tensile strength (if done in one piece in ABS or PETG) but I don't think it would be stiff enough without more internal structure than I plan to use. By the time you have similar stiffness and strength, I think a formed plastic would be heavier. Besides the fuselage is almost 3 ft long and I don't have the equipment to vacuform something that size. (On the other hand, that would solve the problem of all those passenger windows in the Vega, Orion, and Air Express....Hmmm, I'll have to think about that!)

On my Dinah prototype I vacuformed the nacelle shells in 030 ABS. I used that mold to work out the methods (inspired by Harpye's build logs) to form foam with a solid mold. I don't have the numbers in front of me but the foam shells were significantly lighter and once covered with glass on both sides, MUCH stiffer. So much so, that I was able to get further weigh savings by lightening the motor mounts. So that's what I used for the plane in the build log, even though it meant building a new mold to accommodate the thicker foam shells.
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Old Sep 02, 2010, 12:11 PM
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Valencia, CA
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I believe the interior formers on the original were laminated "hoops." If you did that, you would have a hollow interior that would be no problem for the interior detailing.

Pete G.
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