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Nov 08, 2018, 04:38 AM
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Goldberg Valkyrie from short kit


I seem to have a thing for the 'gentle giant' class of old-timey planes. It's the wing structures that grab me the most--how a completed wing looks just speaks to me sometimes. I'm not sure where, but at some point I stumbled on a photo of a Goldberg Valkyrie (Originally from 1937) without covering. "That's Nuts," I said, "but it's beautiful!"
Original article part 1: http://www.theplanpage.com/Months/2301/valkriept1.htm
Original article part 2: http://www.theplanpage.com/Months/2301/valkriept2.htm

The darn thing stuck in my head and has become a bit of an obsession--the look of a trussed wing is just so.darn.cool. Google and RC Groups brought me FrannyB's awesome build, but then I was sad, I don't see myself building up wing ribs like Franny and Mr. Goldberg. (over 1,000 pieces to the wing alone) Here's Franny's build thread--she is truly amazing. https://www.rcgroups.com/forums/show...Valkyrie-Build

But then a ray of light--buried in the posts--a short kit might be accessible!
A few emails back and forth with Dan at Laser Technologies [lasers (at) centurytel.net] (I'll do him the courtesy of not making it too easy for bots to scrape his email address out of this post) and making payment arrangements, and I had a Valkyrie short kit. My kit arrived almost exactly the same as Mustang Mark's post in Franny's build thread (post 45), plus a full size set of plans (in three colors no less).

P.S. Dan says he cut two kits when he made mine, so he may still have the other one in stock!

It's taken some time to get the materials together (even without 1/8 strip for the wing ribs, I need 409 feet of 1/8 x 1/8 square balsa--holy cow!) and clear out other projects, but I'm finally ready to start building.

So far I've laid out a wing and have started assembly. I'm working this wing sort of non-traditionally, since I have very precise holes in the ribs and can slide spars through vs. set the leading and trailing edge. That's good, since I'm still waiting for some 5/16 trailing edge stock to arrive to really start setting things together.

This is a winter project, and here in Alaska winter is long (late April early May before the field may be easily accessible and flight-worthy) and the holidays are coming up, so le'ts just say I can take my time. Don't expect rapid progress updates, at least until I get some of the difficult stuff figured out. There's so much going on with Goldberg's 'double elliptical' wing that I'll go to do a thing and look at things on the board and go, "well I need to go research this some more before I can continue because I have no idea how it's supposed to work". More on that in subsequent posts.

For now, a few pictures to kick the thread off:
Photo 1: I use a 2' x 6.5' foam core door as a build base because they stay pretty true with 3" blue foam insulation on top.
Photo 2: The original article contains 'cut sheet' materials lists for each component. The build calls for 1/8 x 72" strips of balsa which are difficult to come by, so I've been using my miter to make a whole bunch of scarf joints. 17 spars per wing, and only 3 of them are less than 36" is lots of angle cuts just to get sosls (spars of sufficient length).
Photo 3: Laying out the ribs to get a look at this beast
Photo 4: Threading wing ribs onto spars
Photo 5: surprisingly straight
Photo 6: This is why I fell in love with this plane. The trussing isn't even in place yet, but the rib design just makes a beautiful lattice pattern.

More to come...
Last edited by fscdm; Nov 08, 2018 at 10:21 AM.
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Nov 08, 2018, 05:35 AM
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I've great admiration for anyone prepared to take on building a Valkyrie! I saw one flying (free flight) here in the UK several years ago at Middle Wallop. It was powered by a Brown Junior and seemed to fly in slow motion, quite a sight. Will yours be FF or RC? what will you power it with?
Alan
Nov 08, 2018, 06:41 AM
'Douglas' to his friends.
Quote:
Originally Posted by fscdm
...More to come...
Quote:
Originally Posted by ukengineman
I've great admiration for anyone prepared to take on building a Valkyrie...
+1

Following with interest. Splendid stuff; more power to your elbow, and thanks for sharing the adventure.
Nov 08, 2018, 10:29 AM
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Quote:
Originally Posted by ukengineman
I've great admiration for anyone prepared to take on building a Valkyrie! I saw one flying (free flight) here in the UK several years ago at Middle Wallop. It was powered by a Brown Junior and seemed to fly in slow motion, quite a sight. Will yours be FF or RC? what will you power it with?
Alan
I plan on RC electric, but I haven't decided on what gear yet. I really like Franny's tail mounted servos and removable tail components for the conversion. With a stabilizer of 4 feet, it will be so much easier to transport with it removed. I'll be using a clear film to cover at least the wing and the tail. It's not traditional, but since the bones of this bird are what drew me to it I'm not going to hide them.
Nov 08, 2018, 01:24 PM
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If there was ever a design that begs for laser cutting to replace many hours of tedium building the ribs before anything else is done then the Valkyrie is The One ! ! !

A really wonderful looking build fscdm.
Nov 08, 2018, 05:32 PM
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Quote:
Originally Posted by fscdm

I'll be using a clear film to cover at least the wing and the tail. It's not traditional, but since the bones of this bird are what drew me to it I'm not going to hide them.
YES!
Work of art.
Criminal to hide it with opaque covering.
Nov 11, 2018, 03:03 AM
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adamtc's Avatar
wonderful model, take your time and enjoy...
Nov 26, 2018, 01:10 PM
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Update on wing construction


Thanks for your interest and encouragement.

Well it's been almost 20 days since my last update, so it's time to make another post.

In that time I've basically been learning what doesn't work to bend a thicker piece of heavy stock trying to get the trailing edge into shape.

I constructed a steamer (some vent piping and a camp stove boiler). That got the best results, but not good enough--my jig bit into the balsa because of the tightness of the radius and the softness of the steamed balsa .

I then tried a hot immersion chamber using PVC and an automotive ciruclating heater. As the temp of the water approached 200 degrees f, the pvc got pliable--I could have bent the pipe into the right shape pretty handily but I started to worry me safety-wise so I shut it down.

I then replaced the PVC with galvanized pipe, and it worked great, except an hour at temp in the immersion created a piece of balsa that was flexible enough to go into the jig, but even after about 6 hours resting, removal from the jig caused the balsa to back out of shape--it didn't hold.

There are several other options for the trailing edge:
Cut the trailing edge out of a single sheet of balsa (Franny did this and it turned out great)
Cut the balsa into enough segments to make the corner.
Make strips and laminate the trailing edge
Ammonia/windex bending

I don't actually have sheet balsa in the 5/16 size, and didn't relish the idea of going up to 3/8, since i'd have to sand away more than 50% of the stock to taper the trailing edge and that's just extra work. I also am a bit wary of the weakness of cutting out of the sheet, although it's probably unfounded given where the forces are applying to the wing.

Because of the extreme forward sweep, I'd have to make lots of sections to turn the corner, and I didn't like that either.

I've read that ammonia/windex makes things more brittle, and I'm not sure I want that, plus I have a leach field septic and I didn't want to release ammoniated wastewater in there and kill off the biome--that's not cool.

So laminate it is! The sheet I have is 36" and each valkyrie wing is 5 feet, so there does have to be a joint, but I could stagger them like bricks in a wall which will be plenty strong. I ended up with the following to help me with the taper (what you see below times 2 to reach from tip to root but this gives me the stepped cross-section I was looking for:
2 ea. 1/8 x 5/16
6 ea. 1/8 x 1/4
2 ea. 1/8 x 1/8

Leading edge:
A fair amount of time was spent figuring out from the plans what exactly happened to the leading edge at the tip--if you build with the tip ribs on the board at the leading edge, the edge takes a pretty severe downturn and puts a bend in the spars. That didn't seem right, but I finally found what I was looking for in Franny's build log--a cross-section drawing that shows the leading edge as parallel regardless of rib orientation. This meant to me that I just need to keep the leading edge parallel to the work--I ended up cutting some strips to the right height to slide under the leading edge--this meant the wing tip ribs came off the board at the leading edge. The trailing edge they remain on the board according to that drawing. I don't have a picture that shows my implementation of that very well (I measured at the wing root and cut strips to maintain that height on down the wing under the leading edge. At least there's the drawing from Franny's log. The leading edge balsa was supple enough to bend without issue to the correct shape.

After all that and 20+ days thinking, staring, nudging and attempting to bend, I finally sat down and glued everything I have so far--all the spars (minus the root rib, since it needs dihedral), the l/e and the t/e. Next up:
Wing tip assembly (balsa plus inlaid reed? Never done it before, but I think it'll be simpler than the trailing edge...
Trussing
Joiner stuff (I still have to figure out what to buy for this, carbon fiber seems like a good thing). The short kit root and 2nd rib are plywood, and it came pre-cut for 3 ribs with holes for round joiner material in a few places plus some slots for plywood-style too, I just need to get it all figured in
Sheeting at root and tip.

There's plenty of work do yet, but it feels like I'm beyond the stuff I felt like I had no idea how to conquer. I really want to lift that thing off the board and look at it in space (and see the laminations from the underside) but it's as flat as it's gonna be right now, and until I get that wing tip set in it's not worth it no matter how much I wanna peek. More soon
Last edited by fscdm; Nov 26, 2018 at 08:11 PM.
Nov 26, 2018, 01:31 PM
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owlsabie's Avatar
Wow! What a beautiful wing
Nov 26, 2018, 06:06 PM
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A wonderful wing. I really admire your patience. Thank you for posting.

Richard.
Nov 26, 2018, 06:29 PM
'Douglas' to his friends.
Patience is the key, and it seems that you have enough bucket-fulls for the job. And a very fine job you're making of it. I had to do laminations (on a very much smaller scale, but still...) for the first time, and was very apprehensive. It turned out very well though, and I learned a lot. From the photos of your efforts, I can only congratulate you on having, it would appear, made absolutely the right choices. Long may that continue..! Thanks for sharing this adventure in such vivid detail.
Dec 01, 2018, 03:31 PM
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Root rib angle for dihedral and wing tip work


This week has been a bit crazy. Elbow deep in my clothes washer on Tuesday to replace the drain pump and major earthquake impacting family and clients in Anchorage, Alaska. Everyone is pretty much shaken but ok at least, and it'll be a while before infrastructure is 100% down there again. I felt it 360 miles north, through a mountain range sporting the continent's tallest peak as buffer mass. That's how powerful it was.--pretty amazing amount of energy there when you think about what that all means. HOWEVER--back to the Valkyrie.

I worked on the rib 1 angle to set the proper dihedral. FrannyB's post 109 (https://www.rcgroups.com/forums/show...&postcount=109) has the angle at 9.6 degrees for a wing panel length of 60 inches with a tip 10" off horizontal. An online calculator has it at 9.594. Although 9.6 drops the tip a by a hair, I'm completely incapable of building to that kind of a precise tolerance anyway (even the 0.6 in 9.6 is probably a stretch for me, so--no problem!). Following Franny's lead, I made an angle block at 99.6 degrees. That Franny may not have invented the techniques she uses, but her documentation of the process on her Valkyrie build has been an absolute gold mine.

I also cut balsa sheet for a wing tip and spent time slotting a loose tongue and groove for extra strength. A 1/4" flat file seemed like a good idea at the time, but in retrospect because the vertical faces also remove material from the inner faces of the joint surface it was not optimal. If i do that again, I might turn to layers of saw blade clamped together like BMatthews in this post: https://www.rcgroups.com/forums/show...&postcount=100 .

Only after the joint was finished did I realize the purpose of the 3/16 reed I'm supposed to inlay around the tip edge--that'll have strength for days. <doh>. Ah well, it'll be that much stronger--onward!
Dec 02, 2018, 02:45 AM
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For those butt joints, I have glued then drilled diagonal holes through the joint and fed cocktail sticks covered in glue through the holes. Replace the reed with either thin wire or nylon cable used for strimmers.
Dec 02, 2018, 12:04 PM
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Quote:
Originally Posted by adamtc
For those butt joints, I have glued then drilled diagonal holes through the joint and fed cocktail sticks covered in glue through the holes. Replace the reed with either thin wire or nylon cable used for strimmers.
Good idea--I'd thought about drilling and using small dowels pre-glue but that tactic sounds even better. I have the reed, so I'll at least try the inlay. I'm enjoying the challenge the Valkyrie is presenting in terms of 'well--never tried that before' quite a bit!
Dec 10, 2018, 01:28 PM
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The trusses! So. Many. Trusses!


This week I got the wing tip reed bent (about 30 minutes in boiling water and then into the jig. I learned a great deal on this small scale for the larger bends I was trying to do--I had to let the reed dry 100% completely before it stayed in the desired radius. Partly dry and it would still spring outward.

While that was setting I turned to the trussing in the first 10 or so bays. So many compound angle cuts! Dang it all if it doesn't look pretty awesome in an already awesome wing though. Observant viewers may notice some trusses missing at R1 & 2. I'm leaving those out until I get the joiner bits in place. It'll be easier to 'fit and fettle' with out having to work around them.

I made a sad discovery yesterday evening--the awesome laser-cut kit I got included plywood reinforcement for each wing panel and the first three ribs are slotted to accommodate those. The first two ribs are plywood as well--and it's not a simple slot arrangement, the braces have to be slotted in rib 2 before you glue rib 1 in place, which I've already done. Sad day. In my defense, on the wing panel drawing, these pieces are not featured or called out. I'm going to reach out to the kit seller to suggest augmenting the wing panel drawings to call these out. In the mean time, instead of cutting the root rib out to set this brace, I intend to cut some plywood to fit through the slots from the root rib on this panel and then slip some additional reinforcement bits in to approximate what the original part was doing. Delays, Delays! I really want to get this wing off the board and see it in space!

I'm expecting more joiner assembly parts and some hardware to cut a clean groove in the wingtip to inlay the reed today. With any luck I may have a completed wing in a week or so. Catch you then!


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