RE: Fuel tank on CG
 

Well, as I was "Experimenting" with my hovering today, and again, it would throtle down or sometimes up on it's own. It got worse with the lowering fuel level. A few times it nearly stalled, but I managed to roll level and throtle back and keep it running. I would like however to get constant fuel flow. That's why I had the question about wich to get. It just seemed the pressure from the exhaust wasn't enough to carry the fuel up to the carb.

RE: Fuel tank on CG
 

I think your going to be surprised at the amount of pressure that a regulated system produces. When I first got my Cline I had to go through that !QUOT!learning curve!QUOT! like with everything that is new and we're unaccustomed to using. I was using a Sullivan tank, one of the soft flexible types, and was shocked to see the thing blow up like a balloon and spread the sides of the fuse on my UCD. Needless to say I decided to put the original tank in the plane since it's the harder, less flexible polyethylene plastic which took care of that problem.

Remember that the pressure is !QUOT!checked!QUOT! in the tank by a one way valve in the muffler pressure line and can't escape once it's in there, other than by pushing the fuel out through the clunk line and to the carb. Something you have to get used to is the refueling procedure with a regulator. If you pull the cap off the clunk line first there is still enough residual pressure left in the system to create a stream that will !QUOT!pee!QUOT! about 5 feet, emptying the tank in the process.

Don't ask me how I know this....

You should always pull the vent plug first and relieve the pressure. I have gotten in a hurry and took the plane home without defueling it and only realized my error after a few days. Upon pulling the vent plug that familiar whoosh of air greeted me just like I had flown the plan 10 minutes earlier, I was amazed the system held all that pressure as long as it did without bleeding it off!

Don't worry pressure simply isn't an issue with the regulators, there is plenty to do the job at all times.

RE: Fuel tank on CG
 

Hey RobertC,

I did a request post asking how the UCD flew with the tank on the Cg with a 91 powered engine, no one replied. How did yours fly fly with this mod? Did the CG balanced out just right dry? This will be my winter beater, so I will have my skis on it and powered with a Saito 91 GK

RE: Fuel tank on CG
 

Cool, thank you guys, I really appreciate all the suggestions. I plan to get a regulator, hopefully I'll be able to sustain a hover longer...

RE: Fuel tank on CG
 

Striker,

Sorry I missed your request, but the question is a little difficult to answer since I have never flown the plane *without* the tank on the CG! Also, this is my first 3D plane so I am not the best person to ask how much 'better' it flys.

As for balance, mine is currently a little behind the recommended CG without any additional weight. You might notice that my battery (1650 Nimh) is strapped to the former just behind the trailing-edge of the wing. I cut a small hatch in the fuselage about halfway back to mount the RX (and eliminate the need for extensions on the rudder/elevator servos-- the ailerons needed them anyway!). I had planned on moving the battery back but have been advised against it (too much mass in a weak part of the plane... something that I agree with now).

I am running my YS on Powermaster 20/20 and the plane goes like a rocket (and I am only on my 2nd gallon... still lots of smoke). Can't say for sure how the Saito will pull it, but I'm sure there are many others here who could!

RE: Fuel tank on CG
 

Striker,
I flew mine with a .91 all last summer with the tank on the CG. I started out with the tank in the nose and the difference in flight charateristics is noteworthy to say the least. With the tank in the nose you sart out several ounces nose heavy and get more tail heavy all through the flight and it's NOTICABLE. With the tank on the CG it flies the same from take off to landing and maneuvers like hovering and water falls are easier since tail heavy planes do them better.

I fly mine with the CG at 6" back and you have to "fly" the plane into a landing, it will not simply sink in once the throttle is chopped, takes getting used to but isn't a big deal. The .91 OS will do everything you would want to do with the plane, except on very hot days in the summer, will not pull out of a hover under those conditions.

I finally broke down and got a Saito 100 and the performance increase was well worth the cost. On hot days it pulls out well and on cool days it's a rocket, worth every penny I spent for it. I have been running an APC 15 x 6 and 15% Wildcat fuel with BOTH of my engines. I tried 15 x 4W and the 16 x 4W and didn't like them as much as the 15 x 6 which seems to offer a good combination of hovering power and level flight speed that isn't too fast for the plane..

RE: UCD
 

I have one and its the best flying plane I own, I have a OS91fx on mine, Ive done some weight mods but this is the best plane ever Yes it does have a 1 peice wing no it is not permanently attached

RE: UCD
 

airmcn_2 , what prop are you running, and have you used a tach on it yet? If so, what RPMs are you getting?

RE: UCD
 

I'm using apc 13/4W its made for acro flying I'm reading 13500 on my tac

RE: UCD
 

From what i understand, the Perry regulators act as pumps as well. Is this true? Perry recommends just having a vent tube for you tank, but not connecting it to any muffler pressure.

Also, How did you guys reinforce the landing gear and firewall. Did you take it off, reinforce it and then pur them back on?

RE: UCD
 

The other day while tacking down the runway after landing to bleed off some speed, my landing gear came off with the block it was mounted to. It was no big deal, I just epoxied everything back together since it was a clean break. I also added a couple of 1" drywall screws in the backside of the landing gear from just above the wing mounting holes.

There are a couple of us at the club with U CAN DOs we have all had to make minor landing gear repairs.

RE: UCD
 

Thanks Shogun and RobertC for your replies.

Shogun, I am used to "flying in" my planes on landing as I have been flying a H9 Edge 540 with a ZDZ 50 last summer. You actually have to point the nose down when coming in until just before touch down. I will be using a an APC 14X6 for starters and since I wil be flying in winter, I should have good power. I figured that the CG will be constant with the tank on the CG line, but just wanted to now if it was more unstable there than in the nose. I will try it there as you seem to have fun with it. Mine will fly a bit differently as it wil be on skis adding a bit of lift at higher speeds and makes the airplane a bit heavier as well. I will post my findings here, after I fly and thanks again for your replies.

Have fun.

RE: UCD
 

I will be making a wider landing gear form mine. I will extend the block width and hopefully it will have enough surface area to hold on to prevent tearing off.

Will post pics on my site.

RE: UCD
 

Which you guys found to be better for hovering/TRing the APC 14X6 or 15X6 on the Saito 91?

RE: UCD
 

Striker,
I was using an OS .91 FS and tried quite a few props with it, the 15 x6 was by far the best balance for thrust to speed. 14" props seem to be fighting for a grip on the air, wasting a lot of energy and not holding the plane up except at full power, at least in my part of the country. The .91's are pretty closely matched when it comes to RPM's and power output so name brand probably won't make a difference to the performance in the plane, I think the OS is a bit heavier though. The APC 16 x 4W is the best prop for hovering but a .91 really struggles to spin it and the throttle response was pretty sluggish which is not what I want when hanging a couple of feet off the deck. I also found that the plane doesn't want to T/R easily with anything else than the 16 x 4W, the 15 x 6 will do it but very slowly, 14x 6 and 15 x 4W wouldn't do it at all on my plane.

With mine the balance is right at 6" back and I really like it there. Like you were saying you have to point the plane at the ground and resist getting on the elevator till it's just above the ground when landing. At 6" it's not bad at all but at 6.25 mine got difficult to land in the wind and all it took to get it there was 1/2 oz. stuck on the tail right in front of the tailwheel. With the tank on the CG you really SEE the difference a minor change in CG can make and I mean RIGHT NOW! I think having the tank on the CG really helped with inverted stuff as well since I don't have the weight up front trying to drop the nose through the first minutes of the flight.

new pics
 

[8D]some new pics - just after the rain

RE: UCD
 

ok here is one for both of you. take your gear off, pull the tank out, now taketwo peices of fiber glass put one from the sloped part of your nose where the cowl covers, run it from forward to aft wraping it over the gear mounting block and around the bulk head that holds your wing in, epoxy that with 12 min. After that dries take a nother peice and run from starbord to port (righ to left) covering the landing gear block and the peice of glass you just wrapped over it previously, you only need to run it about 1/3 of the way up the fuse. make shure you cut away the monofilm just where the glass is going to go this obvioulsly gives you a better bond to the wood. after done cover the small peices where you cut off the monofilm. and put gear back. you will never have to fix your gear agian!!!!! This whole prosess took me about 1hr and i'll land mine anywhere be shure to use the glass you get from the hobby store, this way its not too thick. There you go. all better oh ya dont forget to recut the hole for your wing to push into the bulkhead, Later Chris Mc Nair

RE: UCD
 

ok here is one for both of you. take your gear off, pull the tank out, now taketwo peices of fiber glass put one from the sloped part of your nose where the cowl covers, run it from forward to aft wraping it over the gear mounting block and around the bulk head that holds your wing in, epoxy that with 12 min. After that dries take a nother peice and run from starbord to port (righ to left) covering the landing gear block and the peice of glass you just wrapped over it previously, you only need to run it about 1/3 of the way up the fuse. make shure you cut away the monofilm just where the glass is going to go this obvioulsly gives you a better bond to the wood. after done cover the small peices where you cut off the monofilm. and put gear back. you will never have to fix your gear agian!!!!! This whole prosess took me about 1hr and i'll land mine anywhere be shure to use the glass you get from the hobby store, this way its not too thick. There you go. all better oh ya dont forget to recut the hole for your wing to push into the bulkhead, Later Chris Mc Nair

RE: UCD
 

Hi Shogun,

I will take yur advice on the APC 15X6 prop. I like TRing and will later try the APC 16X4, as I will have a bit more power in winter. I will also install an on board glow driver I built, igniting the glow plug for almost 1/5 of the throttle travel. I can also assign it to come on with a switch when I am TRing.
I will place my tank on the CG as well.
I really appreciate your replies.

RE: UCD
 

Hi Shogun,

What size of tank were you running the Saito 91 with?
Were you flying more than 15 minutes at a time?

Oops, just realized you are using the stock tank.
By the way, I got myself two 15X6 APC props today :)

RE: UCD
 

The stock tank is plenty, since you tend to fly this plane at lower throttle settings the fuel goes a long way, unless you plan on hovering it the whole flight!

I had an OS .91 four stroke on mine(pre surpass) and it had comparable power to the Saito .91 but weighs more.

RE: UCD
 

Hi All,

I'm a bit jacked off, just got back for my first outing with the ucd60. It failed the club noise test, 82db max on all sides @ 7m, front and exhaust side were 85db!!!!! non exhaust 79db well inside rear was 80db again well in.
I'm using a new saito 100 on coolpower 10% with an apc 15x4w on the stock gp mount, I think I'm getting alot of drumming/airframe rattle.
Anyone had this problem? I've just fitted some thin foam tape to the wing seat and a small silicone extension to the exhaust stub.
I'm thinking I may have to go the whole hog and fit a soft mount, was thinking of maybe a dubro one, any ideas?
It was pulling 8800 on the ground on only it's 3rd tank, wound in the bottom end needle 3/4 turn from factory and the throttle response is like a switch! no coughing or hesitation, I thought I might get a problem with the tank position as std, but it only floods when the tank has just been filled, nice low idle as well.
So should I go for a 16x4w to lower the revs or maybe a 15x6 std apc? how about a soft mount?
I'd be grateful for any info, had this model ready for a couple of months now but not been able to get to the field with good weather and someone to do the noise test so I'm desparate to get her passed and flying.
This is my first 3d model in 20 years and i can't wait to fly it!
Cheers all

RE: UCD
 

Wot, on the 100 Saito the APC 15/6 is the general consensus and that big ol' wing is like a drum, lots of vibe. How well is the prop balanced? Thats a big contributor to vibration. With an exhaust extension mine came in at 79 db. I can't count the rotations when I balance, it seems endless but with results near perfection. Vibration kills. Joe

RE: UCD
 

Cummn thru, what sort of revs do you get with a 15x6? Prop is balanced and I don't actually seem to have much vibration now that I've leaned the bottom end in, thats taken the lumps out of the 100 and it now appears fairly smooth for a large single. the control surfaces aren't vibrating much, sounds to me like it's the big bang of a 4c echoing in the wing, I hope the foam tape will help, I've got a speedy bee with OS15la that was real noisy in the wing till I added foam tape, forgot about that and didn't fit it to the ucd until after it failed the test!
Will the 100 spool up quick enough for hovering with the 15x6? I just don't want to go out and buy another £12-£15 prop that'll bog the engine down if the money would be better spent on a soft mount.
cheers

RE: UCD
 

Also got 3mm carbon rods all round, ball joints at servos, metal clevises at surfaces, jr591 on ali/ele, hitec 645 on rudder, no slop in any surface yet. Didn't want to go down digital route until I'm happy I like 3d!
cheers