JW ...
.91FX...? not had any trouble with this beast have ya....2.8.BHP ...This is lawnmower power....Just put a new .91FX in the GP Extra....then started hearing all this yapping .."Trouble with the .91FX....." ..." Worst O.S. engine ...." nonsense ..Cheer me up ... tell me its ok !

Cheer up!
The OS 91FX is a great ringed piston engine, not one of OS's peeling plated cylinder wall engines. I have three and they all start easily and consistently run fine.
I have two UCD 60's powered by OS 91FX's and the other one is in a Hobbico Extra 300 AWARF.
Who knows, maybe I got the only three good ones. What is the likelihood of that?

Jeff, loved the winter pictures with the skies. You are set for the outback.....

Joe - the fuel tank located so far aft would concern me. I know you are well ahead of any CG issues, but you have to be pushing it a little. Hope this works with no dead weight up front. Looks like you are working on your best UCD version to date. How many is this so far?

The Space Walker. Now thats been around for a while. In fact I nearly bought one of these before buying the UCD. Nice all around fun airplane.

It'll be okay,I have 2 of the OS91FX engine's ,One is NIB and one is in a GP shoestring, It has had some tuning problem's at mid range , but the idel and top end are sweet.....JW

Hi Roger, Ya gotta love a cub on ski's ,This is one of the funnest plane's to fly, Iv'e ever had ....The spacewalker is almost done , I can't wait to fly it .....JW

Roger ,Joe & Co...
Just read Rogers note about the tank concerns...before i put mine there ...well.....had i better not...? i thought that if you coul put your tank over the C of G ..so much the better...? cheers Dave.

Roger, This one is "ol' # 4". Long story. With extensive and frustrating checks and double checks of the radio components and each time everything checked out I might add, it took my first two UCD's to find out that I had an intermittent glitch. OUCH! Both had engine damage to make matters worse. So........... trashed all the Futaba gear and in #3 installed all new JR equippment, stem to stern. I'm all set, what could go wrong. A dozen flights with the new setup and loving it, the crystal popped out of the RX !!!!!! As anal as I am about this stuff I never knew you should tape the crystal in. Oh well. As far as the tank and CG. On 40 sized craft the center of the tank and the CG are within 6 inches of each other. On this long fuse the center of the tank is now 10+ inches of seperation. As the fuel draws down, I've experienced a good deal of chenge in the CG in flight. On the last three my 5 cell battery was always in the aft. of the compartment. So if it has to go forward its no big deal. Now the only change is the weight of the plane as it burns up fuel. With the tank on the CG you still have the option of makeing the CG as mild or wild as you want. Joe

Good morning guys.

Joe, as always, I learned something new today that I had never thought about. I've never taped the crystal in place, but it sure does make sense now that I know about it. I do use Futaba in nearly all my planes. Using Hitec in the UCD with Futaba Rx. Interestingly enough, the only servo failure I've ever had was with one of the new Hitec's right out of the box. Also had a cracked ceramic filter in a Futaba Rx. once that cost me Giles-II. Futaba said the filter cracked from a hard landing, or from the crash. Go figure! I've never used JR, but many of the guys at our field use JR and very happy with their products. Frankly, it seems that any of the known name brands produce good quality products with few failures, but nothing is ever 100%.

Lord L, Joe is a bit more aggressive in placing the tank this far aft, but it appears to work well for him, though he does state that as the fuel drains from the tank this becomes more noticeable concerning the balance of the airplane. If I were going to do this I would first want the CG just a bit nose heavy for the maiden flight, and until I felt comfortable with the plane before moving it back. As the old saying goes, a slightly nose heavy plane will fly just fine, but a tail-heavy airplane won't fly. If you feel comfortable with flying a maiden flight with the tank in a more aggressive CG position then do it, but be prepared for the fuel drain changing the flying characteristics, which could catch a pilot off guard at first. Placing the tank in this position would certainly make the CG check more critical on a plane that has never been flown. I'm not questioning the position of it as much as I am simply wanting to make sure you are prepared for the unexpected with a plane you haven't flown yet. Would hate for you to get it up in the air and find it's squirrelly due to the CG becoming tail heavy as the fuel drains.

Roger, Thats just it, my first were stock setup so I am now familiar with what to expect. Get out and fly, the planes characteristics are mesmerising to the point that you may well be low on fuel by the time you realize that you have to bring it in. On doing some landings right off with a full load of fuel its very sweet, but just so your not wondering as to why it may not handle on aproach as it did earlier with a full tank. Let me specify that there is not a difference so great that it won't land just as easily when empty but keyed to this knowledge you may now pick up on it. It was much more evident once my CG was beyond 5 1/2" On landings, this plane makes any pilot look good. Joe

P.S. 2 strokes put out more pressure than 4 strokes, but still not enough pressure to push fuel from a tank at a greater distance. If this were not the case, all planes would come with the tank on the CG right from the manufacturer.

Hi, there. I just bought a u-can-do 60, it's still in the box, but something in the manual caught my attention. According to the instructions, if I don't have ailevator programming in my radio, I should use a reversing harness for one of the elevator servos. Now, looking at the pictures on page 19, showing a setup without mixing, it clearly shows elevator servos at different locations relative to the elevators with the servo arms in opposite directions. Obviously, with this kind of setup (just like my now departed Laser 3D), there's no need for a servo reverser. I have a computerized radio but it has no ailevator capabilities,and I do have a servo reverser but I don't know if I should try the manual's setup first. Please advise. Thanks.

Hi , I don't have a reversing harness ......JW

J.W..... now your in for it...! ...need to talk to ya awl later ....i'm on " Drape duty "...again, Aaarrrgghhh....! This C of G thing.... dont go away ..! Dave

The plane is balanced with the tank empty , so putting the tank on the CG is fine, the plane won't be adversely affected when fuel weight is added ...It's on the CG line, Iv'e filled the tank on mine full up ,took off, turned and landed still full up... now adding the 14oz's foreword of the CG when the tank is full , and the plane still handled great ,Correct me if i'm wrong, but if the plane is hovering the tail act's as a pendulum , Now if all gear is centered in the middle of that pendulum, wouldn't the plane fly better?... I don't see any problem's mounting the tank on the line, I only see Positive's in doing that.....A very good contribution to the Ministry Of Aviation.............JW

I don't know anything, I didn't see anything ,I wasn't even there!!!!.........[sm=lol.gif].........................I'll be here....JW

J dubya, what, are you going to dig a trench with that shovel? I see no shortage of elv. throw there. Joe

I like the Box corner's.....The end point is at 140% U&P , I Gotta have it in case the engine quits or something, it will swim through the air like a dolphin... The second Ucd3d will be under construction very soon, I'll have to keep you posted with progress reports......JW

Drapes, I mean Dave. The C of G thing is like balancing a curtian rod on one hook. Joe

J.W
.......Yeah, Yeah....and if you were there ...you were sleeping...


Right, we may need the fathers guidence to help us through these troubled waters ...

Dont know where to start on this, its a straightfoward enough concept , but awkward to explain , heres what iwas going to do :-

With everything standard exept the tank in its new pozn, and 2 1/2oz weight 3" aft of the firewall, balance the beast to 4 7/8 " Call this point 'a'

Add afurther 11 1/2 oz to the 2 1/2 ..re-align your balance machine to get the model level call this point 'b'

Remove all the weights, re-level the beast, call this point 'c'

Midway between points 'b' &' 'c' ......should be the new optimum balance point ... you used to take off with a slightly nose heavy model ,then landed with a tail heavy model[sm=confused.gif]

Joe, Roger, Jw ...
I know i've gone wrong somewhere ,so im off to make a custom balance machine ....from spare drape cords & rods....

As Spock, would say.......That is logical.......[:-].....JW

Dave, One piece of wood as a base and two wooden dowels with a slightly rounded off point on one end of each dowel. If they are 1/4" dowels then you need two 1/4" holes in the base at 14 1/2" seperation center to center to stand the dowels in. That will put them directly under the spars. Since you don't have the little swivel things for the top you can use double sided tape stuck to the wing, that will prevent the dowels from puncturing the wing and you can put marks on the tape for your CG. Cheap and easy. As far as your point A,B and C theory, well......whenever you do drapes you seem to go off the deep end. Joe

Just thought .....I've a GP Balance machine somewhere ...unopened ..! But...some guy is telling me " 5.5 to 6" ..should be fine.." for the new c of g with the tank in the new pozition... hell that dont seem right ...its only 3/4 inch or so rearwards of what you guys where flying at ...With 16. 5 oz 10" + further foward ...there's got to be a correct way to calculate this .... oh... got the Du- bro hinges ....like you said ...impressive..!

LL, I replied to that post as well. Hope it cleared things up. Joe

Joe ...yeah thanks i'd 99% got a grasp on that ..i think what i was driving at was that with that tank @ the front you had a fuze that had a variation in its COM, from take off to landing.... with this new tank on the c of g... this variation is reduced if not eliminated ... so couldnt the c of g be a bit more ... sort of 'optimised', rather than compromised to suit nose heavy to start ,then tail heavy 15 minutes & 14 oz later...? thanks Joe.

My English is getting worse ...i should be taken awayand shot... but then again i've doing drapes...!

Regardless of the tanks position when balancing the plane for your first round of flights. Lets say your "maiden flights" until you get used to the plane, go with the 4 7/8" recomendation. Once you got your wings on this plane start to experiment with the CG. The plane, when balanced with the tank empty, starts your flight with a slightly nose heavy plane as you burn off fuel and when you are prepared to land empty, the plane is now properly balanced. At 4 7/8" with the tank empty or full, 4 7/8" is nose heavy for your introduction to this model. When a tank is any where on the model other than the CG it acts as a ballast that changes with volume, therefore resulting in slight changes in the CG. With the tank on the CG it is now just a load effecting only the over all weight of the plane not affecting the CG at all. The plane just gets lighter as it burns fuel. On my last one I worked my way up to 5 1/2" CG. Now on this model with the tank on the CG my balance point will still be 5 1/2" Joe

O.K. Joe what your saying then is completly forget trying to calculate any new c of g for a centre tank, start with something that you know to be safe, and work backwards....sort of trial & error..that'l do for me then ! ... Could i do the pull- pull rudder thing as well now Joe ?...using drape cord ...or do you want to wrap that round my neck....?..!...thanks Joe !