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Scratch building a Goldberg Ultimate bipe

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Scratch building a Goldberg Ultimate bipe

Old 12-23-2021, 09:53 AM
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Outrider6
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Default Scratch building a Goldberg Ultimate bipe

I have been a modeler for about 40 years. Built over 40 kits, most of those being 35-45 years ago. I love building. Even scratch building.

Back in the day, when these Ultimates first came out, I built one. It was just about the coolest plane I ever had. I moved, and had difficulty finding a suitable field to fly it from, so I sold it. Now I have access to a good field. When I get done (essentially scratch) building my Parkflyer Plastics OV-10, I plan on having a go at a Goldberg Ultimate again. I would rather not pay $300-$400 for a kit on ebay (when I find one), and will get far more satisfaction from cutting every piece in it myself. I have the downloaded plans and instructions, have found a source for all of the parts I can't make, and have lined up 2 sources for printing the downloaded plans at full scale for me. I will cut and bend the aluminum for the struts myself, and buy a fiberglass cowl and wheel pants, and a plastic canopy for it.

Once I free up my workbench and gather some funds, I plan to start getting stuff for it. I may do a build thread about it. I have already found another thread about it, which is many dozens of pages long, with lots of helpful information to glean from it. That will save me some thinking and figuring. I am thinking of powering it with a DLE-20 (mainly to save a good bit of money). I had an OS 120 in my previous one, and that engine was perfect for the plane. It was wickedly aerobatic, but very easy to fly, and landed like a trainer.

I am getting really excited about building one of the coolest planes out there. The thing just has some really sexy lines.
Old 12-28-2021, 06:10 AM
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I have an Ultimate I bought at a swap meet for $20. It was a partially built kit. The guy who had it built the fuse but screwed it up and quit. I fixed his mistake and finished out the build. I put a Supertigre .90 in mine and covered it in cloth and dope. Cowl from Fiberglass Master. Good thing you sourced the parts. The kit plans don't show the patterns for the ribs, among other things. The Ultimate has a weak point and that's the landing gear. I've seen a lot of guys replace the stock wires with aluminum. The aluminum doesn't absorb the shock from a hard landing so well and it busts out the bottom of the fuse. I would be scared to put a DLE-20 in it too. Too much weight and too much engine for that plywood fuse. The plans show a K&B .65 which is a joke but they also caution anything beyond a 1.20 4 stroke. I've seen many fly on the Supertigre .90 so that's why I chose that engine for mine.

If you can get ahold of a book called, "Bipes" by Harry Higley get it. He shows many upgrades to the Ultimate that greatly improve it.

carl
Old 12-28-2021, 07:04 AM
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Originally Posted by carlgrover
I have an Ultimate I bought at a swap meet for $20. It was a partially built kit. The guy who had it built the fuse but screwed it up and quit. I fixed his mistake and finished out the build. I put a Supertigre .90 in mine and covered it in cloth and dope. Cowl from Fiberglass Master. Good thing you sourced the parts. The kit plans don't show the patterns for the ribs, among other things. The Ultimate has a weak point and that's the landing gear. I've seen a lot of guys replace the stock wires with aluminum. The aluminum doesn't absorb the shock from a hard landing so well and it busts out the bottom of the fuse. I would be scared to put a DLE-20 in it too. Too much weight and too much engine for that plywood fuse. The plans show a K&B .65 which is a joke but they also caution anything beyond a 1.20 4 stroke. I've seen many fly on the Supertigre .90 so that's why I chose that engine for mine.

If you can get ahold of a book called, "Bipes" by Harry Higley get it. He shows many upgrades to the Ultimate that greatly improve it.

carl
I just searched for that book, and saw how rare (and very expensive) those books are. Too bad, because I would really like to have one, especially considering that I now own just about every Harry Higley tool that there is.

When I first researched the DLE-20, it seemed to me that they were much lighter than any 4-stroke 120, and maybe half the price (gotta love the horribly wrong and lacking BS spec's published by the now defunct Tower Hobbies - those bumbling idiots show the OS 120 being about 5-6 oz heavier than the DLE). Then I read that they were a little heavier and only a little less expensive, making the only 2 advantages being the cost/availability/usage of fuel, and the ability to swing a larger prop. Lots of conflicting info on the internet to sort through. Good thing is that I have lots of time until funds become available, and by then I will have thought through just about every little detail.

I wish this forum software allowed users to edit a post long after it was posted, because I need to clarify that when I mentioned aluminum struts, I actually meant only the cabane struts.

One of the sets of plans I found include tracings of the multiple rib profiles, as well as tracings of many (or all) of the fuselage formers. I am a retired mechanical engineer who has built over 40 kits, so I can figure out things like this, but I never complain when the job gets made a little easier and precludes mistakes that I might make when figuring.

I am seriously thinking of making my fuselage entirely from balsa, except for the firewall and anywhere that things are screwed onto the structure. I am well aware of the poor qualities of lite ply. I am also aware that doing so will probably change the balance of the plane, so I will probably have to make adjustments for that.

One of the biggest problems is the current absence of reasonably priced fuelproof model paint such as Lustrekote. I have ordered a small sample of clear System Three Pennant, to experiment with clearcoating over rattle can Krylon or Rustoleum that comes closest to matching the Monokote or Ultracote that I will likely use.

This will be a very fun project (with a good bit of frustration along the way), with some hopefully really cool end results. Besides my H9 1/3 Cap, the Ultimate that I previously built/flew was the coolest plane that I ever owned.

edited: Finally, if not for one pesky detail, I would love to enlarge those plans about 5% (making the plane a good size/weight for the DLE-20), then find or make a quiet muffler for that engine (I despise the sound of 2-stroke engines, especially when they are loud). However, then I would have to make myself a cowl, wheel pants and canopy, because I would not be able to find those. I could make the 'glass stuff, but the canopy would be a real problem for me to make. Pesky little details everywhere I look.

Last edited by Outrider6; 12-28-2021 at 07:32 AM.
Old 12-28-2021, 05:55 PM
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I hate ply fuselages too. Heavy, prone to popping glue joints, and don't absorb the shock of a landing like balsa at all. Keep looking for the Higley book. Prices vary wildly. You might find one at Perry. The larger prop requirement of the DLE will cause ground clearance issues. I'd run a fillet of bunny fur around the inside of the firewall too You should have enough rudder to counteract the torque.

If I was going to do another Ultimate, I would go with a larger size and a gas two stroke. Something in the 40-50cc range, and ditch the Goldberg.

From memory, here are the improvements recommended in the Higley book:

1. throw away the stock cabane (center) frame and use 3/4" wide aluminum instead. Mount it on the outside of the fuse using 4-1/4" nylon screws instead of inside the fuse. This makes it easier to cover and much easier to repair in the event of a crash.
2. Beef up the top wing in the center and run a tube to guide the center wire so it goes in easier.
3. Drive the elevators using 4-40 hardware and run one servo for each half.
4. Make new interplane struts out of 1/8" ply and face each side with balsa so you can sand to an airfoil shape. Cutout the balsa to form around the ribs at the attachment point to hide the screws. Permanently mount screws to the ribs then attach the ribs using nuts and washers. I made a special tool to to screw on the nuts. It's a socket epoxied to a dowel. I can place a nut in the socket and screw it to each mounting point pretty quick.
5. Drive each aileron pair with one servo and use 4-40 hardware (anybody would do that anyway).

I think that's basically everything out of the book except the details and pictures. He recommends making a jig to form the center frame which is foolproof.

carl
Old 12-29-2021, 06:30 AM
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Originally Posted by carlgrover
I hate ply fuselages too. Heavy, prone to popping glue joints, and don't absorb the shock of a landing like balsa at all. Keep looking for the Higley book. Prices vary wildly. You might find one at Perry. The larger prop requirement of the DLE will cause ground clearance issues. I'd run a fillet of bunny fur around the inside of the firewall too You should have enough rudder to counteract the torque.

If I was going to do another Ultimate, I would go with a larger size and a gas two stroke. Something in the 40-50cc range, and ditch the Goldberg.

From memory, here are the improvements recommended in the Higley book:

1. throw away the stock cabane (center) frame and use 3/4" wide aluminum instead. Mount it on the outside of the fuse using 4-1/4" nylon screws instead of inside the fuse. This makes it easier to cover and much easier to repair in the event of a crash.
2. Beef up the top wing in the center and run a tube to guide the center wire so it goes in easier.
3. Drive the elevators using 4-40 hardware and run one servo for each half.
4. Make new interplane struts out of 1/8" ply and face each side with balsa so you can sand to an airfoil shape. Cutout the balsa to form around the ribs at the attachment point to hide the screws. Permanently mount screws to the ribs then attach the ribs using nuts and washers. I made a special tool to to screw on the nuts. It's a socket epoxied to a dowel. I can place a nut in the socket and screw it to each mounting point pretty quick.
5. Drive each aileron pair with one servo and use 4-40 hardware (anybody would do that anyway).

I think that's basically everything out of the book except the details and pictures. He recommends making a jig to form the center frame which is foolproof.

carl
Thanks for that info, too. It all will help me greatly. I think I can figure it out from what you described. If memory serves, I did that tube trick in the upper wing, back when I built my first Ultimate. I think I used inner Nyrod, which I use quite often for lots of things - far more often than I ever use it for actual control rod.

I will keep searching for the Higley book, hoping to find it at less than nearly $100.
Old 02-03-2022, 03:32 PM
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If you're going to Perry, you might find that book for $5.

carl
Old 02-27-2022, 02:45 PM
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Update: I am in the process of ordering some printed plans, have ordered some supplies, am about to order landing gear from TNT and then the cowl, wheelpants and canopy from Fiberglass Specialties. I just got a killer deal on a new Saito 100. Since I will be using balsa instead of lite ply for most parts, my plane will be lighter than a kit, so I think the Saito 100 will fly it fine. I won't be hovering, so I don't need a 1.5/1 or 2/1 thrust/weight ratio. 1.1/1 will be fine, for me. I was seriously torn about using a DLE-20 for several reasons, but I would have needed to make several modifications to the design to accommodate the DLE. Enlarging the design by about 5% would have taken care of that issue, but then I would have needed to make an enlarged cowl, canopy, taller landing gear, etc. Not worth the effort, for me.

As I always do (even with every single purchased kit), I will be making some modifications to the design, as I build it. I expect that I will have an outstanding plane when I get done with it. Looking forward to when I can start cutting balsa, and I will probably be updating this thread (or starting a new one) when I actually start building.
Old 03-22-2022, 04:41 PM
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Post up some pics when you get it moving along.

Carl
Old 03-22-2022, 05:22 PM
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I will. May be a while until I have the funds to buy the wood that will cost a freaking fortune. There is currently a Goldberg kit on ebay for $445 plus a ton for shipping, but it will cost me far more than that to build it myself. But I get the extra satisfaction from scratch building, along with a bunch of design and material changes. Been fiddling around with the wheel pants, axles, etc. - doing what I can with the materials I already have. The landing gear from TNT should be here any day. Tonight I started on the template for the ribs, which will be a vastly different and unconventional way to make ribs (if it works). Having a complete woodworking shop (sans a lathe) helps a bunch with what I can do.

If this goes well, it will be about the 50th kit I have built in about 40 years, and it will be the pinnacle of my building "career". I thought the OV-10 I am almost finished building would be that pinnacle, but this Ultimate is going to take the cake on that. Nearly $200 for the wood to build that 47" wingspan OV-10, so probably well over $300 for the wood for this Ultimate.

I also finished breaking in my brand new Saito 100 today. Kinda funny that I am going about things in a kinda backwards order, but I do what I can, when I can, with what I have. When I found a brand new Saito 100 for $250, I said the wood is gonna have to wait. All of our tax refund money is long gone now, so it will be a month or two until I can start buying wood (except for the wood for the ribs, which I already have).
Old 04-21-2022, 06:03 PM
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Question for those who have actually scratch-built a Goldberg Ultimate:

When building the fuselage, how did you frame it? Did you:

1) Cut fuselage parts from lite-ply, to mimic the kit? As in tracing the patterns onto sheets of lite-ply, then cutting them to shape.

2) Cut the fuselage parts from balsa sheet, instead of lite-ply, to mimic the kit? As in gluing 3" or 4" balsa sheets together, then tracing the patterns onto the large sheets, then cutting them to shape.

3) Stick-frame the fuselage out of balsa? As in maintaining the outer shape, but built from sticks and narrow strips (like a SIG cub fuselage is built), instead of wide sheets.

I hope my description of the 3 different methods makes sense, or maybe someone did it yet another way.

I am trying to figure the best and most economical way to scratch build mine. Hopefully, a few have done this already, learned from the experience, and recall what they did. I can save significant weight by building it from balsa, instead of lite-ply. Plus, if done correctly, balsa would be even stronger than lite-ply, as well. As in bending strength; not impact strength.
Old 01-03-2023, 03:55 PM
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Originally Posted by Outrider6
Back in the day, when these Ultimates first came out, I built one. It was just about the coolest plane I ever had. .
I feel the same way about this plane
With the OS 1.20 4 cycle it weighed close to 10 pounds IIRC. ..[or maybe my memory is out of wack]
There wasn't in my opinion any dead weight or poorly chosen materials in the design.for a kit...since the lite ply pieces would make assembling the kit more foolproof [and the kit less expensive...?].
If you see a weight savings and better strength with balsa...then by all means sign me up...!


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Old 01-14-2023, 02:52 PM
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IMO ditching the lite ply fuselage sides and cut them out of 1/8 medium balsa would be the way I would go. The turtle deck is another place to save weight. The 1/32 ply is not only heavy but it’s expensive as well. If I were building one I would cut a turtle deck out of foam and use that to form a turtle deck out of a couple laminations of 1/32” balsa sheet. Using the stock plastic cowl as a mold, you can lay up fiberglass parts that are half the weight of what is commercially available. It’s a bit of work but you could possibly end up with a 7lb Ultimate.
Old 01-17-2023, 04:17 PM
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If I was going to build a Goldberg Ultimate from scratch and wanted to ditch the ply I would draw the outline of the fuse on paper then fill everything else in. Maybe copy the basic design of an Aeromaster or something. The wings are already feather light so nothing needed there.

carl
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Old 01-17-2023, 09:51 PM
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Originally Posted by carlgrover
If I was going to build a Goldberg Ultimate from scratch and wanted to ditch the ply I would draw the outline of the fuse on paper then fill everything else in. Maybe copy the basic design of an Aeromaster or something. The wings are already feather light so nothing needed there.

carl
Well for me it's been almost 30 years since I built mine...but the lite ply sides were pretty well hogged out with "lightening holes" if I recall.
OK...weigh all the liteply that comes with the kit then weigh all the balsa that replaces it..
What's the net difference...?
Lite ply is crumbly stuff...especially with a bunch of lightening holes in it and especially after the plane experiences some bumps and bruises.
I was running a "bargain priced" plastic 15 x 6 one day and during a vertical climb the prop exploded and the torque reaction ripped the firewall loose from the fuselge sides. The throttle cable and fuel lines helped keep the engine tied to the plane.. I don't remember the details of the repair..but most likely some fiberglass cloth and epoxy was involved.
What I DO recall during the original build was beefing up the firewall with real aircraft plywood as well as the wing strut mounts.
The mount I used for the OS 1.20 was aluminum..so these were places where the plane started picking up some serious weight.
I did a "mock up" assembly using the plastic mounts that Goldberg supplied and there was just NO WAY I could see ANYONE USING THAT PIECE....
Old 01-18-2023, 05:11 AM
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I agree that hardware selection is important as well. To date we have mini servos that put out 140oz and battery tech that is much lighter. Somewhere around 2012 I did a full on weight reduction effort on a Lanier 1/3 scale Laser 200. First thing I did was use balsa for the fuselage sides. The final weight was 15 lbs on the nose, powered with a DA 50. Not bad for an airplane with a 97 span.


Old 01-18-2023, 08:16 AM
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For the fuselage, I ended up gluing up 1/8" thick balsa sheets together, attaching a pattern from the plans, re-drawing the lightening holes to be as structurally sound as I saw fit, then cutting it out by X-Acto knife, bandsaw, then scrollsaw for some of the lightening holes. For lightening holes that I could not reach with my scrollsaw, I used a Dremel like a router, then cleaned up the edges with sandpaper.

Everything, except for the outer struts, is framed now. Still need to sheet the top front and rear of the fuselage, attach the tail feathers, and build all 3 struts.

This build has been WAY more involved and challenging than I envisioned. Especially with tons of design changes along the way (while maintaining all proportions). I have to keep trying to not "paint myself into a corner" while incorporating those changes and not having any pre-cut parts. After this build, I think I will stick to complete kits. Having other hobbies and duties, and not being able to focus on building for long periods, it is difficult keeping my mind in the build, like I used to do. If an idea comes to me while doing something else, and I don't act on it or at least write it down, then I forget it by the time I get back to the bench. Getting old sucks.
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Old 02-01-2023, 12:35 PM
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Originally Posted by Outrider6
For the fuselage, I ended up gluing up 1/8" thick balsa sheets together, attaching a pattern from the plans, re-drawing the lightening holes to be as structurally sound as I saw fit, then cutting it out by X-Acto knife, bandsaw, then scrollsaw for some of the lightening holes. For lightening holes that I could not reach with my scrollsaw, I used a Dremel like a router, then cleaned up the edges with sandpaper.

Everything, except for the outer struts, is framed now. Still need to sheet the top front and rear of the fuselage, attach the tail feathers, and build all 3 struts.

This build has been WAY more involved and challenging than I envisioned. Especially with tons of design changes along the way (while maintaining all proportions). I have to keep trying to not "paint myself into a corner" while incorporating those changes and not having any pre-cut parts. After this build, I think I will stick to complete kits. Having other hobbies and duties, and not being able to focus on building for long periods, it is difficult keeping my mind in the build, like I used to do. If an idea comes to me while doing something else, and I don't act on it or at least write it down, then I forget it by the time I get back to the bench. Getting old sucks.

You just gave me an idea. I have the plans and am putting together the parts to make a short kit with my laser. The fuse has been haggling me for quite some time as it is too long for my laser table, and getting long sheets of lite ply has been difficult. I didn't consider making up sandwich pieces to form the fuse out of smaller sections, but I do now.

First though, need to get the 1.8 scale B-17E parts in the system and cut before the next project. That one will be mostly balsa ply with either G10 or Carbon fiber laminates. The only 5 layer plywood will be for the bomb bay structure to support the main spars, everything else will be light weight strong lamination's.
Old 05-12-2023, 08:37 AM
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Update: Gotta do what I said I would do - post a picture. I just finished the outer strut mounts, so it is almost completely framed.

Next step is to sheet the top front of the fuselage (once I verify that everything involving the fuel tank is perfect before I lose access), finish and fix a few things, then sand and prepare for covering. I haven't even began deciding which color scheme I will use. If this thing ends up in the 8 lb range (I think it will), it should fly real sweet with my new Saito 100. My first one had an OS 120, weighed probably 10 lb, and the performance was outstanding. Hopefully, this one will be even better.

I thought that since I built one of these when they first came out, it would be an easy build. It most certainly was not easy, at all. I made tons of design changes - not to the outer shape, but to the structure. That complicated things greatly. Plus, even with the insane prices of kits on ebay, this was FAR more expensive to build from just a set of plans, with the cost of wood these days.

Please pretend you don't see all of the filler on this, which embarrasses me. I had some issues with some things, which I tried to fix. I used to be better at building, and am not getting better at that, but I am still pretty good at fixing my screwups.


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