Carl Goldberg Ultimate 10-300 Build
 

Hello Everyone:

My plan here is to scratch build a 10-300 with the following process and mods:

Laying out the parts in cadd, printing them, cutting the parts by hand.
Convert to EP
Modify the wings so the trailing edge and ailerons are ribs and sheeting, not the solid tapered balsa
Bolt the upper wing on instead of the wire
Using aluminum gear instead of the wires.

Any insight on the conversion to EP would be great, CG info, motor, ESC, battery, etc., this is my first electric build, and only my third build, one of the previous was a 10-300.

I am hopeful at the end I'll have two sets of cadd drawings, one for GP and one for EP, with the EP set having the mods for a battery hatch and the location of the hatch. The GP will be pretty much straight up with no real changes except the wings.

I'll be beefing up the landing gear area, and building it with the slots for the wires in case someone does want to use the wires for the gear. My build just won't use that method.

Once I get this build done, and any tweaks done to the parts, I'll send the cadd file to National Balsa for a laser cut kit and build it again, making sure that everything all goes together.

So far, as I layout, print and cut, there has been a lot of little tweaking and sanding, to get it all to fit, so hopefully I've transferred all those little extra cuts and sanding to the cadd file.
Here is where I started, with two 12" x 48" lite ply sheets.

More to follow.

Subscribed ;)
Bryan

totally interested in this process ok kit build. subscribed as well.
Trevor

Subscribed

This is Awesome!! Subscribed as well... :cool:

Totally agree. Awesome.

Any updates on progress?

Slow progress.

I cut most of the wing ribs, started construction, and realized that I was a bit short on the trailing edge, so had to re-design the ribs and I am re-cutting now.

I'll get an update out on the fuse construction later this weekend. The main four sides are complete and they went together well.

I am waiting on a motor selection before finalizing the firewall installation and completion of the fuse.

I think the 54" Ultimate will be great with EP. If you want to do a second one might I suggest blowing it up 5% to a 57" wing span and building it around a 20cc gas power plant. AW has a 60" made for a 35cc but the smaller size would be great for transportation.

David

I have not done an EP yet, all my others are GP, and my other Ultimate had the Super Tigre G90, any suggestions on motor and esc? I'm not necessarily looking for something unlimited 3D, but something that isn't a dog either.

Kind of mid-range right now.

Here is my progress so far. Fuse is together enough to mount the firewall, but need a motor first, and since the main part of the fuse was the sides and top, I've completed that part and moved on to the wings. The fuse went together well and all the formers, so no problems there, at least yet. The upper formers are completed, and just sitting on the fuse top to make sure that they all lined up.

The wings are a different story. Since I'm going to try and build them without the shaped LE and TE, I'm having to redesign the ribs, and my first attempt wasn't correct.

The images attached show my plan. I'll be tying the TE together with a 1/8th x 1/4 basswood and then capping the end with a 1/8th piece of balsa. I'll slip a balsa block for the hinges to mount to in between the basswood.

Once I have that done, I'll sheet it all the way out to the back edge of the aileron.

http://www.rcuniverse.com/forum/atta...mentid=1944059http://www.rcuniverse.com/forum/atta...mentid=1944060http://www.rcuniverse.com/forum/atta...mentid=1944061http://www.rcuniverse.com/forum/atta...mentid=1944062http://www.rcuniverse.com/forum/atta...mentid=1944063http://www.rcuniverse.com/forum/atta...mentid=1944064

+1
All eyes and ears here with a lot of excitement and a little contempt.
Bryan

I should have noted also, for those that have constructed this one, you'll notice that all the wing ribs are the same. I'll be installing a servo in each wing, so I didn't need to cut the ribs like the kit.

I will provide a cadd file with those original ribs for those that want to build the original kit.

Also, the landing gear area is about half per the kit and half re-enforced since I won't be using the wire, but after market landing gear.

Looking good :)

Looks great…

I've been thinking about scratch buildinga body with balsa stick instead of the ply.

Question; outside of redundancy, is there any real argument for going with 2 servos for the ailerons? our 20 year old ultimate is still flying great with the one.. ( not counting the bang up job I did on it 3 weeks ago that I'm currently fixing ). Just seems like added weight, I can't imagine the roll rate being any better or responsive…

Just asking since I have a kit to build and have been debating this one.

I don't see the two humps to attach the cabanes top and bottom. Are they just not in the pic? As far as the two servo VS one aile servo debate. The two servo is easier IMHO and takes the slop out of it.

david

Nice catch on the "two humps". They are on rib number 7, and that rib I've cut out of 1/4 inch ply, so that is going in last. The upper stringer on the mid point of the rib is just sitting there. I'll pull that off and slip in rib 7 and then re-align everything and glue it all up.

Have you seen how Seagull does their 54" Ultimate compared to the Goldberg? The strut on the SG is a little wider on top and bottom and the "bump" slides into the strut instead of the strut sitting next to the bump. It is a little cleaner look. The strut would need a little redesign but the finished product is worth it if you are as picky as I am :-) .

BTW 1/4" ply is WAY overkill in this area. 1/8" is more than enough. 1/8" ply off the shelf is already a lot stronger than the lite ply supplied with the kit, You will be adding weight you don't need IMHO.

David

Hi David,

Yes, I have seen the way Seagull did the cabane supports and liked it and I've been thinking of how to incorporate that into this build. Certainly having the 1/4 rib would be tougher to get around.

Thanks for the "humble opinion" on the 1/4" ply. I was told this was a weak point, so that's why I went with 1/4" ply. First plane I built, I thought it seemed a bit overkill. Might give some 1/8th ply a try and see.

The cabanes on a biplane are designed to keep the wings parallel. Other than that they don't do a lot. when the forces on the wings on a particular side push the wings together, they hold them apart. Not a lot of twisting forces, not a lot of pushing pulling forces. the wood of the cabane struts spreads the forces out along the contact points of the top/bottom wings. The bolts themselves are there just to keep the cabanes in place.
Balsa USA's phaeton biplane has the two cabane struts mounted by sticked the wire of the N strut through a hole in the balsa of the wing, with a bass block behind it.. no screws, no bolts and it works great. only a small metal washer at the end stops the wire from moving away from the wing.
http://www.rcuniverse.com/forum/atta...mentid=1944657
long story short, 1/8" should be more than fine.

The other thought I have, is in the 20 years with my ultimate I've had bad landings 3 times… bad landings meaning crashes. Each time the cabane mounts broke… but thinking about it, I would have rather had the cabane mounts break and fix a small piece of ply then have had the whole wing destroyed with the cabane mounts intact.

Like Mattnew, I have owned an Ultimate for the last 20 years. Actually 3 different ones. I fly mine HARD. I have never had an issue with the outer cabanes. I have done a blender hard enough to rip the center alum cabane mount out of the ply in the fuse. (it was a thing a beauty but should not be done with a plane you like) Even that did not hurt the tabs in the wing or the outer cabane. So please use the 1/8" and save your self some weight :-)

David

You might make those supports easily replaceable because they break easily from moving the plane around. I need to fix mine.

Here is my weekend update. Still slow going. Just not much time.

I went ahead and ditched the 1/4 ply for 1/8 inch ply for rib #7. Based on the comments, (thanks for all of them!), I did notice that the lite ply in the kits is lighter weight than good solid 1/8 inch ply I actually found at the LHS, so I went that way. I am planning on a different strut mount, and I have that designed, and will detail that out later.

First picture is everything lined up and done. I glued an 1/8 inch balsa strip to the leading edge and trailing edge. I'll glue either a 3/8th inch x 5/16 balsa stick to the leading edge and then shape, or go see if I can find one already shaped like I need it. The trailing edge you'll see I've first put a 1/4 x 1/8th inch basswood stick there and then put the 1/8th inch balsa to that. This will be the finished trailing edge the hinges go into.

I'll slip in a balsa block between the basswood sticks where the hinges are to give them more to attach to.

Also completed is the ply joiner.

It's looking good! You might be able to find a pre shaped leading edge at the LHS. From my experience though the pre shaped parts are heavier than a soft balsa stick sanded down. You don't really need the heavier stock in this area. You are already building heavier than the stock wing (no offense)and should save all the weight you can in non essential areas. At least IMHO. I piece of soft balsa can be rounded quickly with a razor plane and some sand paper.

David

Thanks David for the comments.

I was actually thinking that constructing the trailing edge would be lighter than the large shaped piece that was originally in the kit. Also, by building the center section and not using the solid balsa also would be lighter. I was a bit concerned with the stability of it, but as I go, I think it will be good.

The leading edge I am hopeful will have about the same amount of balsa when I'm done as the original kit.

I like your idea of not using the shaped balsa. Makes it more of a "build".

Thanks again for your comments!!