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Goldberg Eagle 2 Rescue & Re-Build

Joker 53150

Mmmmmmm, balsa.
Mentor
#1
Yeah, another rebuild. With the wing project finished, the Funtana 90 has been pushed back to the back-burner and I'm currently back to enjoying "small" projects which distract me too much during flying season. As many of you have probably guessed, I've got a lot of planes that need work. Some are from swap meets, some are kits that were partially built (by me or others), and some were "donations". I've had a couple similar kits waiting for work for a while, and each cost me less than $20. First is the Great Planes PT-40, a 3 channel plane I got a couple years ago. Here's what it's SUPPOSED to look like:

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And here is mine. The wing (not shown) is built, but not covered. The staining on the nose is water damage from the building it was stored in for a couple decades. Overall, it's not as bad as it looks, and if I remember correctly the wing is in good (but dirty) shape. Also pictured: Mountain Models Switchback fuselage done up in a T-28 color scheme.

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The other candidate for a 3 channel build is a Goldberg Eagle 2, which I got last year from a guy thinning his collection. Here's the picture from Goldberg:
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The Eagle 2 is in decent shape, and it appears to have been built in 2004 based on a label I found inside. Covering on the fuselage is usable, but will be re-done as I need to make some changes and may as well make it mine with the final design. Oddly enough, blue & yellow is what I just did for the Funtana 90 wing - I may use those same rolls for this one as well. This plane was never finished.

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It was built for a glow engine, and I'll either convert it to gas or electric. Currently I don't have any small gassers that would fit, but this would be a good excuse to get one!

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Like the rest of the fuselage, the tail is pretty usable as-is, but I'd like to re-do the hinges so it has a narrower gap and also round the edges of the surfaces for a little cleaner look.

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Inside, there is no servo tray - doesn't look like it was ever installed, either. I'll just copy the design of the tray for the Tower Trainer 60 I'm building for my buddy Mike. It's simple and effective.

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The wing was mostly covered, although it was lifting heavily in a few places. Option 1 would have been to simply seal the covering back down.

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But.... the edges were in pretty rough shape. Plus I could see a bit of damage the covering was hiding, and that needed to be fixed.

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Covering on the wing came off very easily with a little heat to soften the glue. The blue tape marks ribs which have damage. I think every one of them can be saved, and won't be noticeable if I use transparent covering aft of the spars. Some shear-webbing was also damaged - it's found on the front of the spars and gives the wing a lot of additional strength. The right side of the wing had no real damage to speak of.

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Sheeting at the center of the wing is solid, although it doesn't line up evenly from sheet to sheet. This will be tweaked if I use the transparent covering. I may leave this wing "old-school" and held on by rubberbands.

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Keno

Active member
#2
That is one fine plane and one of my favorites, Continue with your rebuild. It looks like it might have been intended to a 3 channel with the dihedral shown but if you were to add ailerons and take some dihedral you would find an fun flying model. Even if you choose to leave it at a three you could not be disappointed. It will do whatever you tell it to do. it is an excellent old style trainer as with its smaller version the Eaglet. Our Club has trained many new flyers on this Goldberg model as it was easy for them to build and fly.
 

TooJung2Die

Well-known member
#3
Carl Goldberg is one of my favorite airplane designers. All of his airplanes are well engineered and good fliers. Looking forward to seeing this one restored.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#4
That is one fine plane and one of my favorites, Continue with your rebuild. It looks like it might have been intended to a 3 channel with the dihedral shown but if you were to add ailerons and take some dihedral you would find an fun flying model. Even if you choose to leave it at a three you could not be disappointed. It will do whatever you tell it to do. it is an excellent old style trainer as with its smaller version the Eaglet. Our Club has trained many new flyers on this Goldberg model as it was easy for them to build and fly.
It was indeed built as a 3 channel plane. Instructions I found online show it could have been done with ailerons as well, although I have come to like this type of plane on 3 channels, so I won’t be changing it.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#5
So I got bored last night and decided to remove the covering from the fuselage. No damage was found, but I did find a couple joints that weren’t glued well. The fuselage is pretty basic looking and won’t benefit visually from a transparent covering. My thought is to go opaque on the fuselage and transparent on the tail and wings.

I also looked for a small gasser, but none were found in my price range, and I’m bit willing to shell out over $300 for a big named engine. Electric is still an option.
 

Keno

Active member
#7
If you come across an Eaglet you will not be disappointed with its performance. It is my favorite Goldberg model. I followed its design and construct many from 2" foam board (hot wire) to be used as club trainers. The club still has one and it is occasionally flown at the field.
This plane originally flown with a 20 size glow engine but now has been converted to electric. Happy rebuild.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#8
Looks like I may have scored a NGH 9cc gasser, which should be just about perfect for a plane this size. It’ll be the smallest gas engine I’ve worked with so far.
 

L Edge

Well-known member
#9
Goldberg and Sig were the models of the day during the 70's. Being a flight instructor at the club provided me a lot of time training new pilots on these models.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#10
She's naked! :) Stripping the covering was a pretty easy task, and only a small amount of color stuck to the wood, which I think will clean up pretty well for the upcoming covering.

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On the fuselage this is the only real area needing a fix - the sides have separated a little from the top, which will be an easy task.

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This is the inside of the fuel tank access hatch. Hello to Michael!

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No major issues at the tail other than the need to re-hinge the surfaces, and I'll probably use CA hinges on this plane. The transition from vertical stabilizer to fuselage also will get a minor tweak to smooth out the curve. Leading edges on the stabilizers will also be rounded for a nicer appearance.

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Fixing the multiple broken ribs is fairly easy as well, as they're mainly cracked along the grain of the wood. A little TiteBond II applied with a paintbrush, followed by clamps to hold it all straight is taking care of it for me. Sheer webbing was removed in the worst spots and I'll cut new pieces to go back in. The sheer webbing isn't the prettiest, and since I want to do the wing with transparent covering I'll either do transparent only aft of the spar to hide the webbing, or possibly just remove and replace all the sheer webbing with new pieces installed a little more "cleanly" which would let me do the entire wing with transparent.

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Another part that is only cosmetic - the sheet on the right side was trimmed even with the other sheet as it'll be visible through the covering. I may as well do it now, it only takes a couple minutes!

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Joker 53150

Mmmmmmm, balsa.
Mentor
#11
I've officially got the engine for this plane, a NGH 9cc gasser. They were out of stock at Hobby King, but my buddy Mike has two of them and gave me one to use while I wait for them to get back in stock and I can replace it for him. The plane calls for a .40 size 2 stroke glow, and pictured with the NGH is an O.S. LA 46 glow engine. The gasser is a little longer and wider, but there should be plenty of room on the mounting rails for it. The exhaust may cause clearance issues, however.

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As previously mentioned, some of the shear webbing was loose and needed attention. Since I *MIGHT* be doing transparent film forward of the spar I felt I needed to do more than just re-glue the original pieces.

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The webbing came off a little easier than I'd have liked - 15 year old glue gets kind of brittle, I guess... The webbing didn't extend all the way to the ribs and therefore wasn't glued to the ribs, which would have made removal a much bigger pain. Glue residue was scraped off and the surfaces were sanded.

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I'm fitting all of the new webbing to each individual bay, as the ribs aren't all perfectly vertical and they aren't all spaced the same. I'm only gluing to the spars, not the ribs. The webbing was cut just short enough that it shouldn't touch the covering on the top or bottom. If I go with transparent covering forward of the spar this will look much cleaner than with the old webbing.

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Joker 53150

Mmmmmmm, balsa.
Mentor
#12
Re-webbing the wing is done, which is good as I've run out of clamps! :) Overall it was a pretty easy task which will hopefully pay off in the end. Webbing on the right wing was almost all solid, so I'm guessing the left wing had something big and flat sitting on it. That would explain why most of the webbing was broken on that side and why most of the ribs were broken along the grain. On a related note, I looked at the instructions for this plane and it appears there were supposed to be some kind of plastic caps for the wingtips. I don't have 'em, so I'll use some "creative license" and come up with my own design to finish the tips off.

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I've also been looking at the trailing edges of the stabilizers, specifically where the hinges are located. I could have re-used the original pieces, but don't particularly like that style. Instead I'm going with CA hinges on this plane. The trailing edge of the vertical stabilizer had some bad glue joints so I removed it and will cut a replacement. The rudder and elevator are simple designs cut from sheet stock. These will be replaced.

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Joker 53150

Mmmmmmm, balsa.
Mentor
#13
...and so along with replacing the trailing edge of the vertical stabilizer I replaced the trailing edge on the horizontal stab. It was just too easy to replace it now, and repairing it would have taken longer and offered less strength. The rudder and elevator were also cut from new sheet stock as planned. It's really helpful to have a good supply of sheet in different thicknesses, as well as having generic aileron stock (which is what I carved the elevator from).

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Also mentioned earlier, I need to finish off the wing tips as the plastic caps from the kit didn't come with the plane. The original builder rounded the trailing edge a bit, possibly because he didn't have the caps either?? For my version of the wing tips I'm making them like the Sig Kadet has, simple and effective. A sheet is glued to the outside rib and a 45* block is added to hold the angle. You can also see in the bottom left of the pic that I cut off part of the original wing trailing edge (at a 45* angle to give me more surface area to glue) and extended the TE by about 3/8". After the glue cures I'll come back and do all the sanding to get these pieces to their final size.

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Joker 53150

Mmmmmmm, balsa.
Mentor
#14
Wing tips are done, and with that the work on the wing is pretty much complete other than final sanding and covering. For the covering I'm probably going with yellow on top and transparent blue with yellow accent on the bottom. The wingtips are done like the Kadet Senior's design, which worked out well. I added three 45* braces to hold it in position, and then shaved them down a bit so they won't be touching the covering when it gets to that point.

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As mentioned in another build I'm doing right now on a Tower Trainer 60, I've got enough rubber bands to last a couple years - 3 pounds of #64 from Amazon (close to 1,000 total pieces). With that many there is no reason to re-use stretched out bands and risk the wing coming off. The original thought was to convert the wing to bolt-on, but like the Tower Trainer I decided against it, even though it would be far easier on this plane than on the Tower Trainer. It'll be kept old-school.

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Joker 53150

Mmmmmmm, balsa.
Mentor
#16
Time to start filling out the interior a bit. First up is a new servo tray. The original one made for this plane is missing so I used one of the servo trays I got from an estate sale a few years ago. The tray holds the servos, but I still had to fabricate a hardwood mount for the tray. It's recessed into both sides of the fuselage and should be plenty sturdy for the application. To clean up the wiring a bit I used a mesh wire loom. Pushrods will follow.

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Speaking of estate sales (or swap meets), if you fly gas or glow you can never have a big enough assortment of fuel tanks! I've been collecting them a few at a time and typically have something on-hand that will fit the application. Plus, they're cheap, usually $3 or less! Along with this stash of 15-ish tanks I've got a bunch of stoppers, fuel line, barbs, and just about anything else I'll need to plumb a fuel system.

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Here's the lucky tank that'll be used in the Eagle 2, a Sullivan 10 ounce with a beveled front. The bevel is fairly important with this tank, as a front-mounted bung would hit the firewall.

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This one will give me just enough clearance with the tank pushed back into the next fuselage former. Hopefully there is enough room for the ignition module in with the tank...!

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SquirrelTail

Well-known member
#17
Time to start filling out the interior a bit. First up is a new servo tray. The original one made for this plane is missing so I used one of the servo trays I got from an estate sale a few years ago. The tray holds the servos, but I still had to fabricate a hardwood mount for the tray. It's recessed into both sides of the fuselage and should be plenty sturdy for the application. To clean up the wiring a bit I used a mesh wire loom. Pushrods will follow.

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Speaking of estate sales (or swap meets), if you fly gas or glow you can never have a big enough assortment of fuel tanks! I've been collecting them a few at a time and typically have something on-hand that will fit the application. Plus, they're cheap, usually $3 or less! Along with this stash of 15-ish tanks I've got a bunch of stoppers, fuel line, barbs, and just about anything else I'll need to plumb a fuel system.

View attachment 139091


Here's the lucky tank that'll be used in the Eagle 2, a Sullivan 10 ounce with a beveled front. The bevel is fairly important with this tank, as a front-mounted bung would hit the firewall.

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This one will give me just enough clearance with the tank pushed back into the next fuselage former. Hopefully there is enough room for the ignition module in with the tank...!

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I had that same tank and had it fail mid flight causing my fuel to be out on landing.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#20
Not much has gotten done for the past few weeks. I've been flying when possible and also took the family out west for a week's vacation, which was long overdue. My interest for building has also been kind of low recently, so I decided to try and re-ignite the flame with some finish work to remind me what I'm aiming for.

As mentioned previously, I'm using the same covering as my Funtana 90 has, and I figured I had enough to do at least the full bottom of the Eagle 2's wing and half the top. Well, I'm coming up short.... :( I've got enough left to do only one side top & bottom, so more will have to be ordered. These rolls are expensive for how short they are, I really should have looked at the Hobby King film to see if they had colors that were close enough.

So here's where I ended the day after covering the top & bottom of the left wing. I'll finish shrinking the film at the center of the wing after the right side is covered as I don't want the film to come loose where it's only attached to the balsa. It tends to stick much better to other film, making shrinking easier. The covering over the wing tip that I fabricated stretched nicely, and I'm happy with the way it turned out.

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The bottom design is basically the same style as the Funtana has. Not real original, but I like it. :) I still need to get the trim iron out to shrink a few remaining minor wrinkles, but it's coming along and it does make me want to push forward with the rest of the fuselage work.

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