twn

Hey all! This is my first build thread. I am not new to building and I have built a number of kits and arfs. My goal with this plane is to build a strong hairy plane. I will be throwing it around like a lunatic but I also want it light and I still want it somewhat scale in lines.

We have another member in our club building an ultimate so I figured I would build mine now and help him along.

I am going with the OS 120AX and Slimline Q-Series compact pitts. I want to tail mount the elevator servos.



Mods I’m considering:

Cf reinforced stab.
Harry Higgly cabain mod & top wing bolt method.
I’m a little apprehensive of the cabane mod as it requires the cabains to be mounted to the outside of the fuselage. It is VERY strong but takes from the scale look.
Enlarged ailerons by 20-30%.


Any other mods that people have done is very much welcomed and thank you to those who help!!

This build will probably be slow as it is still summer and I'm out flying a lot.

daveopam

My Feedback: (9)

The stab reinforcement is not needed. The stab is short and it's sheeted. I have done some blenders with mine that were a blurr. The stab has never gave way. The stock cabanes are plenty strong. It's the mounting areas that need help. Either glass the tabs in the fuse before you sheet the front deck or use a ply doubler. Or both. I have never broken the tabs but the bolt pulled through, washer and all. The ARF I fly now is doubled in this area.
Also read a thread by Fallingleaf in this section called "Goldberg Ult engine selection" or some thing close to that. I will find it and bump it to the top. There is a lot of good info there on the build and on the installation of dual elev servos.

David

Revy

My Feedback: (1)

I would be the other club member, lol. I built the stab as per the kit instructions. The elevator halfs, however, I added some scrap stock to reinforce the hinge placements. For the firewall, how thick should we go using that motor?

twn

Hey Jason, hows it going? I mowed the field today. Weeds were like 2 feet tall, lol! Grass didn't grow at all and was 20km winds untill 4pm. Got one flight on the reactor. I didn't bother setting up the 50cc 260. I got a spoiler mix in that really settled the wing rocking down in harriers on the reactor.

Any how Rory tells me no less than 1/4" aircraft grade plywood. Lester has some. You could laminate 2 layers of 1/8" 5 ply with some 30 min finishing resin like zpoxy. I was also told not to dremmel lightening holes in the firewall like I usually do. It needs the strength. Also I'm pretty sure even the q-series pitts muffler will stick out of the cowl [&o]

twn

Thanks David!

I have read the fallingleaf postings a few times and there is a lot of good info in that thread and that is why I decided to wait and get a 120ax but I haven't seen any info on enlarged ailerons or alternate top wing/cabane bolting methods cause honestly I hate using rubber bands to secure anything on an aircraft. I want a bolt/locknut solution.

If I do enlarge the ailerons I wonder if skinned ailerons will hold up on this plane. The ones on my 50cc Ultimate are skinned and work VERY well.

Chad Veich

My Feedback: (60)

TWN,

I understand your issues with rubberbands but in this particular instance it works just fine. Not the most aesthetic solution but it works fine and I don't see the retaining wire coming out even if the rubber band were not there at all. I'm flying mine with an OS 1.08 and have had no issues with the stab. I'm generally a warbird flyer and not an aerobatic or 3D type flyer but the Ultimate is a great airplane to just sport fly and keep the thumbs nimble with.

fallingleaf

My Feedback: (1)

Nice to see another Goldberg thread booya!!

I wouldn't enlarge the ailerons they won't make the plane perform any better than stock. I fyou take your time with them and make sure you bevel the edges accurately to give maximum throw you will get alot out of them. Even on 50% throw mine will snap roll on a dime into a ball of smoke and full aileron either way will induce a spin like a blurr. I just don't see the need to mess with the stock set up personally.

I second Dave - no need to reinforce tail. Will just add more weight that you DON'T need or want. With the sheeting and proper use of epoxy to glue tail feathers on you won't need it.

Tail mount servos are good for elevators. Go with hitorque mini servos though - my standard ones are overkill when you have 1 per elevator half.

I toyed with the higley top wing mounting mods - didn't bother apart from the guide tabs for the bracket that the top wing slides onto (a MUST DO). Properly done as higley suggests (like mine!) its robust. I don't use a rubber band I use electrical cable ties. Solid and will not break like a rubber band. They are so cheap you just cut it off when you need to remove the wing.

I would glue some aircraft grade 3/32 (3mm roughly) at least ply under the whole horizontal former that the cabanes bolt onto. Far stronger as this area is subject to a little torsional twist and stress. Worked a charm on mine. I would make a solid doubler (fuse side to side) next time round though.

If in doubt read my thread haha It is a good synthesis of a lot of mods other people have done and there is good building discussion and guidance there from all here at rcuniverse.

Enjoy the build, I found mine became a real journey and I was amazed to watch it take shape and turn into the beast I now have. It will reward you everytime you fly.

flygilmore

Nice plane fallingleaf....but why the paint stirrer for a prop when there are so many better, more efficient choices out there for equal money?

daveopam

My Feedback: (9)

Chad that is one sweet Ult.

On the topic of enlarging the ailerons. Unless you are going to 3D this thing it is not needed. That being said, I wished mine were a little bigger yesterday. I was doing some harriers into a hover and I could have used a bigger bite from the ailes. This is not what the plane was designed for so I don't falt it.

If you decide to go with bigger ailes. Using built up ones would be the way to go. If it was me I would extend the ribs to a point. Then before the rear sheeting goes on,cut the ailes out of the wing to the desired size. Then cap the LE of the aile and the TE of the wing with 1/4" stock and double bevel. Just be sure you put good hardwood mounting points for the horns to screw into. This would be a lot of work, but is also the right way to do it.

David

twn

Some progress...

I went with the cf re-enforcement as I only used strips .007 thick by 1/4" sandwiched one on each side. the cf weighed about 3 grams total...

I lightend the stab where I could. I added a 3/16" square of bass wood on the trailing spar for added strength. The cf re-enforced stab is crazy strong. RevyMaxx can confirm how tough and the weight is only .3 oz more than his non-cf stab. Worth while I think...

With the fin I used the toughtest 3/16" * 5/16 from the kit laminated to 3/16" square bass to toughen it up more for the main spar. The rest is light soft stuff. The fin is tought like nails. Should stand up to massive abuse.

If any one is interested here is my final sanded weights:

I am using a digital food scale so it is quite acurate but the oz side only shows to the first digit after the decimal so...

Stab - 68 grams / 2.4 oz
Elevator Halves (both together) - 28 grams / .9 oz
Fin - 29 grams / 1.0 oz
Rudder - 26 grams / .9 oz

daveopam

My Feedback: (9)

You do nice work! If I could make a few comments/suggestions...... Be carefull on the type of hinge used in the tail. I lost my first ULT cause I used the round Robart hinges on the rudder. These did not leave enough wood, and I broke the stab just above the fuse. I was doing a flat turn about 25' up at the time. It snapped when the fin broke and splattered. Second... while in this stage take a small T pin and put holes in the stringers of the rudder and elev halves. Do this from one end to the other. When you go to cover this big thin flat surface, these holes will let the hot air out of the covering and make it much easier. Third... Take the rear turtle deck out now. First use it as a template and cut the covering out for it about 3/8" bigger than the deck. Then wet the deck and roll it up a little at a time with some tape. After you wet it and roll it tighter 4-5 times, you should have the outer edges touching and taped together. Do this a little at a time. You can split this ply at the back where it meets the front of the fin if you go to fast. I'm sure there is a 4th and 5th they just aren't coming to me right now.

Keep up the good work, david

twn

Nice Ulti Chad!!

U see I am so not a warbird flyer. Don't get me wrong I love em and very much enjoy watching others fly em, they are just not for me. I'm the kind of flyer who loves to flat spin, ke spin, water falls etc untill the cows come home which is the reason for the "stiffening" of my goldberg. I also like crazy power. Straight up like a rocket! lol At present I'm practicing a lot of knife edge, 2 & 4 point rolls and entering knife edge with multiple rolls as well as practicing outside circles.

My buddy has a gb ulti and he found that over time the pin will wear through the mount, at least his did. He did the higgly cabane mod with much stronger aluminum and he STRONGLY suggested that I do it too with the way I fly. I'm just not hip with mounting the cabane outside the fusealage. I'm pretty sure I will reform new cabanes from thicker aluminum but I will mount them inside and just double up the fuse where they mount. I'm still not sure about going with the pin mount or a bolt mod.

twn

That is EXACTLY what I envisioned! But the whole draw back is that I think the larger ailerons will only help with the hovering. My buddy with the ultimate thinks that the airfoil is why this bird doesn't like to be in a stalled state for long (or at all) and once u go into a hover the torque starts to spin the plane and u can't hold it with the smaller ailerons. He figures adding about 1/4" and bringing them closer to the prop stream will help dramatically. But if all I'm gona gain is better hovering I have other planes that do that well... Cause it is a lot of work to do this!

twn

Thank you!!

I plan to use the dubro pinned hinge and will pin/epoxy them to keep them in. They are relatively light and strong and should stand up to a few years of abuse. I will probably use more than the plan shows for added strength. The plan only shows 3 on the rudder. Kinda crazy if u ask me. 3 per elevator should be ok. I will go with 4 per aileron.

Good point on the turtle deck covering idea. I will probably make a template of it tho as I'm still undecided on the covering scheme.

fallingleaf

My Feedback: (1)

I just like the look of the wooden prop I want to go up to a 17x6 though for better thrust and low speed breaking. APC's just look so generic to my eyes.

twn

If you like wood props try a xoar. I can say with experience that my 22-8 zinger pro has WAY less thrust than a xoar 22-8 on my dl50. The xoar definately pulled much harder. Hard to beleive that a prop of the same size & pitch can make such a difference but it did.

Xoar is more brittle tho so take care of it.

twn

daveopam & fallingleaf, I am curios. How much throw r u two using on your ultimates on your highest rate.

twn

Fallingleaf, can you post some images detailing this?

daveopam

My Feedback: (9)

All I can get. The rudder at full delection is 1/4" from the elev halfs. The elev and aile I put all the bevel will allow. I do have 50% expo on the elev up and 60% down. The aile only needs about 15% expo. The rudder about 10%.

David

twn

David, would you say a full 45 degrees on the ailerons?

daveopam

My Feedback: (9)

Close to that maybe. The one I have now is an ARF, and I did not rebevel it. The roll rate is never going to be really fast so get all you can. I did not ask, but I assume you are going to use two aile servos and not the one like the plan calls for.

David

twn

Most definately 2 aileron servos. I have 3 985 new in the pack left from a previous build. I'll probably put them on the elevators and rudder (coreless...) I also have a 5625 kickin around so I'll buy another 5625 for the ailerons and put them all on 4.8v. overkill yes but I have most of them already...

More progress... I beefed up the tabs on the plywood wing ribs as fallingleaf did. I did some lightening... The inital weight of the original plywood was 30 grams. The weight of the new 1/16 aircraft grade ply and cut out pieces was 80 grams not including epoxy, ya WOW & very noticable in the hands.

Final weight is 60 grams. It may only be 20 grams but it all adds up. With my gp extra 300s I manged to remove almost 1/2 lb from the airframe alone. I'm not going to worry too much about removing weight with this plane as the ultimate flies better with a bit of weight behind it. I'm hoping for 8lbs. My buddy in vernon has one at 8lbs with a [X(]YS140[X(] in it. It is awsome!


In hindsight, it would be better to build these with a lamination of 3 layers of 1/16 aircraft grade ply rather than laminating onto the existing 1/8" ply. It becomes too wide and adds diffculty if you want to hide the tabs inside the struts.

twn

A quick update. I am much further along than this and i will get some more pics today and post them. I'm currently fitting the servos in via a plate as fallingleaf did. I'm a bit nervous with this method. I used basswood mounted on the end grain to the 1/16" aircraft grade plywood plates for the servo mount. I punched a bunch of holes halfway through the plywood and a good 1/16" in to the end grain of the mount and used some strong 30 min epoxy (warmed a bit to make it more runny to soak in to the hard plywood better) to attach. Punching a ton of little holes allows the epoxy to REALLY soak in and grab better. I hope it doesn't rip out in a hard blender or insane tumbles... I'm so use to hard mounting a servo to the surface of a wing rather than hiding it. I was just going to mount it this way but I wanted to try the plate idea for kicks.

Any how her are some preliminary pics of the wing construction. I moved the hinge line forward 5/16". I made a jig and pinned all the ribs together and removed the 5/16" from them all at the same time. They are all identical. This will give me a little more than 2" per aileron and should give that extra bite in a hover. I was going to cut the T.E stock down the 5/16" but I'm glad I didn't. The wing, even though is sheeted on the leading edge, is still somewhat flexible and I think that T.E. stock is adding to the strength of the wing. The weight of the bottom wing so far with all of the sheeting on and plywood plates in is 11 ounces. Still reasonable.

I noticed that the right side of the plan (on the wing) is actually 1/4" wider than the left side, lol. I wonder if the designer was drinking the day he drew these plans up. I had to re-cut the dados in the T.E. stock as they didn't line up to the plans. I pinned all 4 of them squared up (faster to do all 4 at once) and made a jig to do this with the correct angle for the ribs. You can see the sanding jig in the pic. This is when I noticed that the right side of the plan was way off. I corrected the placement of the ribs at the main spar so all will line up and is square. I will duplicate this for the top wing.

A bit of a bummer, the bottom wing has a slight warp. It sits up about 1/32" on the T.E. of the right side. I made damn sure all points were tightly secured when sheeting and I accounted for the removal of the 5/16 from the T.E. by putting a piece of that size back in so the sheeting jig would sit in the right place at the center of the wing. I'm not sure how it happened but I'm positive I can get it out when I cover the plane.


Sorry, I should add, I added 1/16" balsa to the top of the T.E. stock to bring it out to the height of the cut ribs and I will have to add 5/16" to the inner aileron stock that is glued to the wing. I don't have any 5/16 so I'll just laminate 1/16 & 1/4 to make it.

daveopam

My Feedback: (9)

Once again Tom, you do good work. I have been thinking about your top cabane attachment. I think you said you did not want to use the wire. The ARF uses two bolts. The only difference in construction is 1/8" ply in the center of the top wing. The holes in the alum A frames have holes in the top that the bolts go through. The bottem of the top wing has holes cut to slip over the A frames. It's apart in the shop right now. I am going to snap a few pics and post back.

David

daveopam

My Feedback: (9)

Not my best pics. I got in a hurry, but you get the idea. It's hard to tell how far in the ply goes. Visibility is limited. It could be one piece 2" wide front to back. I really cant see in there far enough to tell. First pic is bottom of top wing, then top of wing. Both have the bolts sticking through.

David