drumbum

My Feedback: (1)

I have found that if you dont cut the axles down on GP kits you can drill a protrusion hole in the other side of the pant opposite from the mount and then cut the axle off just on the outside of the pant. then take some thin wood(that will still allow the wheel to roll) and drill a hole in it for the axle to go through and epoxy it on the inside inside . Then you can go through grass of any type without the side force that breaks the pants when they are only mounted from the gear side

jzinckgra

My Feedback: (11)

Regarding the handle cg balance method. I've seen a couple posts here that said 1" to 1.25". Just to be sure, this is measured from the rear/aft blind nut on the handle towards the nose, correct?

darryl-e

yes from the back hole forward to the nose of the plane. like i said it was a bit nose heavy but still came in like a baby. many thanks to the people that have built this thread. save me alot of time and headache. like i said earlier it does have a little coupling but i have a ultra rc giles 202 and it couples worse than this biplane. i hope to be able to fly it this sunday again with the new cg and lipo batt's. i would recommend this plane to anybody who is looking for a nice entry into 50 cc gas and loves a biplane

jzinckgra

My Feedback: (11)

The other mods I did were to the pushrods. For the aileron rods, I used fully threaded 2-56 then slid CF tube over that. Went with a ball link on one end and clevis on the other. For the elevator pushrods, I went with Central Hobbies' 4-40 titanium pushrod ends with ball links and 4-40 clevis'. I used JB weld to glue the pushrod ends into the CF (no threaded rod inside). I've done this on my patttern plane and it's held up fine. Hope it works here too.[&:]

iflywhenican

My Feedback: (1)

I've never been to fond of using the JB weld setup. I just don't trust it. I prefer to use the solid 4-40 threaded rod strengthend with carbon fiber rod. Just makes me feel better. Just a matter of personal preference.

darryl-e

as far as the jb weld thing on the linkage. A friend of mine had one pull out on an ailerion on a 40 size twist. the reason was that he had cracked the carbon fibre when he was putting it together. i found that the best way to make up linkage is to do this. use one inch or so of[X(] aluminim on the outside of the carbon fibre then ca the carbon fibre to the aluminum. after this has dried completely take a 4-40 or 2-56 tap which ever size you are doing and then slowely run it into the carbon fibre. This cuts the threads into the carbon fire and then you have the ability to thread in your rod. When i thread the rod in i apply thick CA and thread it in an inch or as deep as your threads are cut with your tap. i then take thin CA and wick it in along the rod and carbon fibre. strong like a bull and i have never had a failure as of yet. but i guess there can always be a first time.[X(]

jzinckgra

My Feedback: (11)

Thanks. Yeah, I decided to remake the ele rods and used fully threaded 4-40 rods then CF over that. A little more weight, but more than worth the extra durability. I like your idea, but I don't have a 4-40 tap on hand, so I just went full rod all the way through.

Regarding the throttle servo: I am using a moki/pitts combo and I can't see how I am going to get a metal pushrod to get not only to the carb arm, but also move freely. In the pics in the manual for the os 160, they make it look like a nice clean shot on the outside of the pitts then to the carb. Not sure this is possible for me. There will have to be some weird bends to get it to work, it it will work at all. I may just put the servo inside and use some golden rod or flex cable.

fishdeth

My Feedback: (2)

I had the Ultimate out to a "End of Summer Fun Fly" last weekend and after a short warmup, I took off, pulled verticle and rooled 2 or 3 times, leveled off an started my turn and silence.... DEADSTICK !!!
I was in a bad position and couldnt get enough airspeed to glide & flare, but I got her down in some tall grass.
Only broke a prop and 1 landing gear leg. (could have been worse)
Spent the rest of the day spectatin !

Jim

fishdeth

My Feedback: (2)

So I pulled the trigger for the Graph Tech LG @ $69.95

Question / Poll :
Do I leave them alone... or paint them RED to match the plane (my preference) ???[sm=confused.gif]???
OR... I might could put on some red TrimCote ?
Thanks for your input !

Jim

RICRAC

I had my ultimate 160 up for its 3rd flight for final trimming, and after start and a turn i hear a loud crack!
And the plane is very difficult to handle so i lower the throttle from half to idle and heading for a emergency landing, and manage to land it.

When i get to the plane i see both upper and lower wing had broke in two!
So i did a inspection of the wings and see both wingjoiners had snappt and the balsa ribs was split.

Anyone had this happen on this plane other than me?


Greatplanes ultimate 160
Os 160 FX

a1pcfixer

My Feedback: (7)

I take it, you didn't read & apply the various 'mods' we've posted here (during assembly).....wing joiner failure is a biggie!

There's been 2 others besides yours, here's one;
[link=http://www.rcuniverse.com/forum/fb.asp?m=4958548]Wing Joiner failure....[/link]

Here's a link to the varous 'mods' we've done....
[link=http://www.rcuniverse.com/forum/fb.asp?m=6057226]GP Ultimate 1.60 'mods'........[/link]

You can 'Search this thread', look for that at right-hand bottom of each page.

Fwiw; Great Planes has replaced the wings for at least one person, entire plane for another.

bblizzard

hi,

i have a gp ultimate 1.60 and a moki 180 to put on it. has anyone tried this combo? the moki has the same power output as the fuji 43 4.1 to 4.2 hp, and it's almost a pound and a half lighter than the fuji, 45 oz w/muffler to 64oz w/muffler. i know great planes tested it w/ and os 160 as well and said it would do 3d w/that motor. the moki is more powerful than the os as well 4.1 to 3.6 hp. would i have unlimited vertical w/this motor and 3d capability? please help.

thanks, brad

iflywhenican

My Feedback: (1)

fishdeth
Did you find what caused your deadstick?...Leave the Graphtec "as is"...Heck, If I paid that much for a gear, I would want everybody to see what it is made of [:-]
bblizzard
I have a friend that has a Moki 2.10 on a Ohio Superstar Ultimate, which is almost the same specs as the GP Ultimate. It is a powerhouse combo to say the least.
RICRAC
I am interested to know what kind of glue you used to join the wings?

RICRAC

I used 30 min Epoxy, and all gluing was ok. There was wood on both sides of aluspar, and joiners was still in place just snapped i two. And in lower wing spar had split, and joiner snapped i the middle.

iflywhenican

My Feedback: (1)

These reports make me nervous, but I have been flying mine for almost 2 years...a few dings and battle scars here and there, but I check my wings after every flight and they are as tight as the day I assembled them. I used G-Glue instead of epoxy and plenty of it. I remember wiping it's foamy nose for about an hour after I assembled them. [:@]

a1pcfixer

My Feedback: (7)

Fishdeth,

What caused your 'deadstick'?

a1pcfixer

My Feedback: (7)

Seems to be that the choice of epoxy or G.G. has little to do with this. Quality & strength of your wing-joiners is
80% of the problem, and mostly recent production runs of this ARF.

I'm just glad to have made my own 'mod' for this issue BEFORE assembling mine!
[link=http://www.rcuniverse.com/forum/fb.asp?m=5014262]Wing joiner 'mod' w/C-F......[/link]

fishdeth

My Feedback: (2)

Not really sure what caused the engine to quit.
It had been 2 weeks since I ran the engine.
The guys running the flightline did NOT have all their poop in one sock... was really poorly run and when they gave you the OK to roll out... you had BETTER be ready or they jumped the guy behind you right up.
So I rotated the prop 3 times to prime, turned off the choke and turned on the ignition and she started with 1 flip !
Gave her a very short warmup and took off.
The only thing we can figure is a big air bubble in the line caused the deadstick.
At home the next day, I put on a spare LG leg I had and another prop and ran her up in the driveway including a GOOD 30-35 second WOT blast..... not a hiccup !
Don't know, but I will give her an extended warmup before taking off next time !

Jim

BTW... I will only gain 1/2 ounce with the Graph Tech gear over the old reinforced gear.
Also I will gain 1 1/4" in width / stance and a whopping INCH in height... maybe more because of no sag / spread. !

So.... Black or RED ????

iflywhenican

My Feedback: (1)

I guess the procedure that you went through may have been the cause...just not enough warm-up time. At our field, we are mostly "on our own" and can take as long as we want for warm-ups and other stuff. "Pressured flying" is one thing we don't tolerate.
a1pcfixer,
It's been almost 2 years since I built my Ultimate, but as in an earlier post I made, I think (but not sure) that my wing joiners were not laminated balsa, but were hardwood. It's just blowing me away that the fact of building the wings creates such a strong "box" and that they are ripping apart so easily!! It would be interesting to know if the top or the bottom wing is first to let go. I don't remove my wings for transport to the field and that makes me wonder if removing and re-attaching may come into play here. I even pick my plane up by the top wing right at the aluspar while handling it.

jzinckgra

My Feedback: (11)

I opted to not perform the wing joiner mods, which may impose some risk, but it would seem that Great Planes engineering could be at fault here, if more and more wing failures occur. I hope mine is not one of them. I used 30 min epoxy and one would think that is adequate. I have put many wings together, and the design of the Ultimate wing joiner part seems structurally sound, but I am not an engineer, so maybe GP should have designed this part better. I may still put fiberglass around the center section of the bottom wing (all around) and maybe just the bottom of the top wing. Anyone do this? Even if there are more failures, it would be hard to prove that GP was at fault due to poor design given the many variables involved. For instance, many guys are using different epoxies, some might not mix equal parts, some might not use enough all together,etc. Then there is the whole engine selection variable.
Does anyone know if GP has willingly replaced those guy's planes that crashed due to wing failure?

iflywhenican

My Feedback: (1)

I agree....
I also came up with a "fix" for you guys that have already built your Ultimate. Simply get some 2" wide strapping tape and carefully place it lengthwise of the leading edge of the top and bottom wings. After that, you can put matching color trim tape over the mod tape if you are that picky...I'm sure most will want to do that to hide the strapping tape. 4" on either side of the alu-spar should be enough to do it..or whatever makes you feel good.

RICRAC

I was thinking of put glassfiber around the lower wing to (on my new wings if GP give me a new one) That mod will give a great strength to the lower wing, and also do a wingjoiner mod.

I think the original wingjoiner is not up to the job, on a plane of this size and wight. There is not much strength in the balsa, or the 2mm liteply.
But i dont know how stong the combo of them is, but i think this type of plane can put about 10 G so that makes the wings to take up 10 times the plane weight like 70-85 KG.
That is like put a normal weight man in the plane when its only supported by the wings, and in those conditions i would not trust the balsa wing joiner.

And i dont know on a biplane is the total weight in a 10 G manoever is split in half of each wing, so its 35 kgs on each wing.

Maybe there is someone here that knows this things and can tell us how it is.

And is there someone who know what forces that cause the wings to break, like airpressure on the leading edges or +/- G forces?

a1pcfixer

My Feedback: (7)

Go back a page to the post where I gave a link to a past crash. Look VERY closely at the wing joiner & center alum piece photo.
It's crystal clear that the wing joiner was the cause of his crash! There's still wood & epoxy on the alum piece.

A fellow flyer had a GP Ultimate this year, until he ran into the club trainer He'd taken off & during such went near vertical & did a steady barrel roll upward. Well, his RH wing tips nailed the trainer & shot it away like a ping-pong ball! His plane ended up crashing due to the RH wing tips being sheared off(up to the interplane struts). Plane was totaled, but his wings were still joined! He'd used my carbon fiber strip 'mod'.

For such a simple & easy 'mod' it gives me great confidence that my wings are staying together. I've got too much invested in that plane NOT to do so.

Head back to that crash link & read about 3 pages past. He states the results.

mrbigg

My Feedback: (21)

Too bad they didn't just use an aluminum tube and socket.

iflywhenican

My Feedback: (1)

I have read on other threads on here that "certain" other mono-wing planes that have "tube and socket" wings are failing also!!! One plane is of exactly the type that I have flown many times with NO wing problems.
How many of us have built a U CAN DO and have read the WARNING ADDENDUM that GP sends along with the manual???