Classic Goldberg Cub Kit
I was recently given a Carl Goldberg Anniversary Addition Cub kit. The kit look to be complete, all parts seem to be there and in good shape. Parts bags are not open. The kit is old and had been stored in the original box for many years. All of the paperwork is also there.
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I am thinking I will build this kit. The instructions are calling for engine sizes between .40-.60 two stroke and .90 4 stroke.
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I am looking at using the Saito .82 4-stroke on the plane. Is this a good choice?
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The instructions talk about shortening the wings to make it a little more aerobatic, but I am a new pilot (learned last year) so I think I will leave the wings long and make it easier to fly. This will be my second plane. I have been (and still am) learning on a 25 year old Eagle 63.
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Is there anything I should know about this kit? Any tips or tricks that might make building easier? Any help would be appreciated. I have built kits before. I built the Eagle that I am flying now.
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One question in particular. The instructions say to use “Jet” to fuel proof the firewall. I remember using thinned 5 minute epoxy for this. Which is better?
What would you guys suggest for covering the plane with?
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Thanks.
</meta></meta></meta></meta>Shortening the wings is called a Clipped-Wing Cub, and was pioneered by Hazel Sig when she wanted more aerobatics from her stock Cub. Built the wing full length at first. Later, you can easily remove the tips.
The only thing special you need to know about a Goldberg kit is it's a Goldberg kit. They are some of the easiest, most fun to build kits out there. The fuselage will go together with interlocking pieces, tape, and rubber bands, and will be almost fully assembled before you add the first drop of glue. Use thick CA on plywood, thin on balsa.
"Jet" is Goldberg's brand of CA. Any CA will work. You can use that or the epoxy. Both work well.
Covering MUST be a fabric-type, IMO. Solartex, Colortex, Worldtex, or any other heat-shrinkable covering with a fabric-type texture will look great on it. IMO, this stuff is easier to apply than the shiny plastic-types like Monokote.
Take your time, read the instructions completely and study the plans. Be sure you fully understand both before you pick up a piece of wood. If you need help, just ask.
Good luck with it!
I agree, the Saito 82 will be perfect.
Cubs can be a bear on the ground, full
size or model size. I also agree with using
Fabric to cover it. I like 21 century fabric
myself.
Bob
Our club field is a grass and pavement. Should I use the grass?
Here is the story of the Airplane whose wing was too big....
Back in the 1920's they designed the Piper Cub. The idea behind this plane was that its designers envisioned that everyone in the country would someday own one, fly it to work, the grocery store, etc.
To make it affordable, they put a very small, inexpensive engine in it. In order for this tiny engine to get an airplane off the ground, they had to make the wing BIGGER THAN IT WOULD NORMALLY BE. So now, this little engine could get this airplane off the ground.
The problem was, it was under powered and that HUGE wing created a lot of adverse yaw.
By the 1930's, the dream of everyone owning one went away when they realized that very few people had runways in their backyard (Not to mention at their grocery stores), but a lot of pilots had them - and they were due for periodic overhauls. Some of these pilots realized that if they put a REAL engine on it, they could "Clip" the wing down to a NORMAL size and relieve some of the adverse yaw and other undesireable effects of that "Wing that is too big".
Unfortunately, now people think that Clipping the wing from the original design is making a radical modification to a good plane. In reality, the original wing was intentionally designed to be TOO BIG and the clipped wing is the correct size.
Now granted, some people have radically clipped wings on various aircraft, And some versions of Cubs have the wing clipped too much, but Goldberg got it right! The clipped version of the Goldberg Cub wing is the ideal size for that airplane.
Try it, you'll like it!
Read more: http://www.rcuniverse.com/forum/m_92...#ixzz0rmvnGDUG
I am seeing a general consensus that the clipped wing is what I should build.
I, too, thought the Saito 82 might be a little big, but the plans actually call for a 90 4-stroke! I actually have an old Enya 46 on my trainer right now. I had thoughts of putting a 40 2 stroke that I have on my trainer and putting the Enya 46 in the Cub. I don't want to fly around at full throttle all the time though, and with the 46 Enya being 1/2 the recommended size 4 stroke engine, I could see why you would have too.
Maybe building a second wing. That way I would have both the full size and the clipped version.
This will be a slow build so as I can take my time and build it correctly. I finished reading the instruction sheet from cover to cover last night.
I was thinking of starting a "Build Thread" while building. I like to read other threads like this. It is really cool to watch one being born!
I don't see a place to really post a "Build Tread" though.
One of the things it says to do is to build it on a table that you can stick the stick pins into to hold parts. What type of wood do you recommend for a table top? I tried sticking the pins into a peace of 1/2 plywood I has laying around, nothing doing, would just barely penetrate. Certainly not enough to hold anything.
Thanks for all the feedback so far. Can't wait to get it started. I will be using a fabric type covering for sure. My father recommended "Fabricote" but I can't find anything on it. I remember him using it way back when. Do they still make it? Was it made by Monokote?
First, although they say up to a 91 4-stroke, that manual was written many years ago when 4-strokes were not as powerful as they are now. You're 82 will be plenty!
Second, don't hesitate for a minute to build the clipped wing. It will still be a very gentle floater. As I said earlier, the BIG wing does NOT make the plane fly better or more gently, it only makes it more difficult to turn.
On the engine. Makes a lot of sence. I have NO doubt that the 82 will be more than enough for me! The instructions do list a range for the 2-stroke, .40-.61, but it only lists the .90 for a 4-stroke, not a range of sizes. I love the sound of the bigger 4 strokes. Should be great!
Thanks for the advice! I am itchin' to get started!
I use foam insulation board 4x8 sheet
from lowes, around $10. That on top
of an interior door, works great for pinning
parts together.
Bob
If I build it with the clipped wing, it stands to reason I might be able to get away with a smaller engine.
Do any of you have any experience with the ASP engines? They are considerably less expensive than the Saito.
Looks like there is a .61 then it jumps to a .91.
Would the ASP 4-stroke 61 power this Cub?
I have this same kit awaiting it's turn on the build board. (two 2'x4' pieces of ceiling tile from your local building centre). I'll be watching this build with great interest. Ordered an Evolution .61 the other day. I'm wondering if this will be enough power to fly with floats. Anybody care to weigh in on this?
ARUP:
Is your Cub on floats clipped as well?
southmountainbob
Nova Scotia, Canada
Right now I am thinking something in the .60 - .75 range.
I talked to the owner of a local hobbyshop here in OKC, and he told me the Saito would work and it would climb streight up with it! It would probobly even hover! LOL!! I hardly think a Cub like this was ment for 3D!!
So, I will be following your, and his advice and go with somethign in the range above. He also told me he would not recommend ASP. He said if I didn't want to spend the money on a Saito to go with a Thunder Tiger or the Magnum, so the search goes on for a power plant.
Mean while Ibuilt a table in what has be come my "hobby room". . Ibuilt it large so Iwould have plenty of room! it's about 8 ft long, by 3 foot deep. Should sufice. Top is nice 3/4 ply so it is nice and flat! Thanks for the advice Taradad, I hadn't thought about being flat being important. Ican sure see why it would be! Iwill try to find the Homasote. Can you tell me more about that?Ihave never heard of it. What about where I might look for it?
I think I will start a new thread when I start the build and link this one to it. If I can find sufficient backing I may start the project tomorrow!
The RCUcommunity here is great! You guys are very encouraging!!
On a side note today, I went to the field this afternoon and got some stick time in with my Eagle 63. It was the windiest I have flown in yet! When I got to the field and took my wing out of the cradle I built, my aileron servo was hanging by the torque rods!! Looked like the old plywood spacers (same age as plane) just seperated and failed. A little gap-filling CA and I was back going.
A gentleman showed up with a little plane that looked like these low wing modern day crop dusters (don't know the name). He had a little trouble with the engine but seemed to have it worked out. He taxied out and took off and it flew nice. After a while he circled back to the south end of the field and the next thing I know I hear "Dead Stick". I looked up and, boy, he was pretty far out. I though to myself "He's never going to make it." Sure enough it went down into some trees. We looked in waist tall grass and Poisen Ivy for more than an hour and a half and never found it . Ifelt really bad for the guy, this was his 3ed flight on it and it was his second plane. He soloed last spring. He says he is going out first thing in the morning to look again.
Our field is very close to a lake, and on the south end of our field is a Hobie sailing club and there was a lot of people there today. I am starting to think someone over there saw it go down and went and took it! Isure hope not, but these days you never know. A locating beeper would have been nice in this incident.
I actually have an old Enya 46 on my trainer right now. I had thoughts of putting a 40 2 stroke that I have on my trainer and putting the Enya 46 in the Cub. I don't want to fly around at full throttle all the time though, and with the 46 Enya being 1/2 the recommended size 4 stroke engine, I could see why you would have too.
Maybe building a second wing. That way I would have both the full size and the clipped version.