Impressive letter from Ultra RC. BIG thumbs up to them.

The 2 in 1 bellcrank work well, however a pain in the butt to get in. It would easier to do the pull pull set up.

Impressive letter...Yes, True....mostly

(Torque)
"Now, there is such a thing as too much power / torque. I once had a plane that was so over powered, on vertical climbs, the plane would do a slow roll to the right. Flying straight and level, it would roll to the right."

Only if your propeller was turning backwards. Have you ever seen an airplane torque roll to the right? I think he meant left.

(CG)
"With the problems being noted, I would recommend changing the CG to a more nose heavy position along with the other changes in the elevator control throw as mentioned in an effort to solve the situation."

Actually a more rearward CG, closer the CL will result in a slightly higher AOA before a stall occurs because you are offloading some of the weight from the wing. That is also why a plane with a more rearward CG will also fly faster.

I do applaud Brian from Ultra-RC for writing this letter. It shows a great deal of knowledge, concern and support for his products.

Hi I have the same plain and mine fly's like a dream. Make sure youd SG is not to far back and the elevator should not move more than 20 mm up or down on maximum input on the stick. I do Sportsman Precision Aerobaticks with mine and I must tell you there is already about 3 people that also whant to buy the same plain. Maibe you can try to move your SG more to the front, mine is about a 90 mm back of the leading ege of the wing closest to the fuse.

Try that and see what happens.

Good luck

Arrie

Well,
I installed the twin HS81 servos in the tail. Now I have precise elevator movement of both halves. The plane still snaps very easily, in fact, it seems worse. The plane is dead on with lateral balance. As for the CG: I added 4 ounces of lead to the nose and the plane balances at 4 inches back, which is in middle range of the recommended CG point. I also have the battery pack and receiver way up by the fuel tank. Short of adding more lead, I can't get the CG much further towards the nose, although as mentioned its in the middle of the range anyways. This balance point was with an empty fuel tank.

I also checked the thrust line by going straight vertical. The plane tracks straight up without veering off to the right or left, indicating that I probably am good as far as my thrust line goes.

Maybe I need to accept the fact that this plane won't tolerate extreme elevator throws. I guess I am used to my Extreme Flight Yak with 50 degrees of elevator throw. I can give full throw at any speed and the Yak won't snap in the least bit.
Anyways, at this point, i may consider selling the katana as its becoming frustrating trying to figure this out.

I think most folks around here use the term snap and don't fully understand what the term means. A snap is a condition where one wing(or a portion of a wing panel) stalls before the other that causes an abrupt roll in the direction of the stalled wing. A snap-roll is a maneuver that uses this one-side-stalled condition to rapidly rotate the airplane around it's axis on purpose. If your plane does this and you didn't mean for it to then you have what the full size pilots call a departure from controlled flight.

With every airplane I set up one of the first tests I do is to apply full elevator at full throttle and see if the plane will track 3/4 of the way through a loop without departing. I usually find that I will get a departure while either entering the loop or at the top and sometimes it will get me at the exit but the throttle is usually reduced on the back side of the loop so if you depart there your really using too much throw. This ALWAYS has been the result of too much elevator throw. I land the plane, dail out some throw and repeat the test again and keep doing this till the plane will track through a loop at full power with zero departures. This becomes my low rate setting and I fly the plane there till I either lose it or sell it, whichever comes first.

The intersting thing is that most of the modern designs have such huge surfaces that they reqauire VERY little throw to get the job done effectively. I usually find that most planes have more than adequate elevator authority with as little as 10 -12 degrees. You also need to understand that ANY change in balance will affect this setting and you'll need to re-fly the plane and do the full-pull test again to make sure your plane will not stall and depart.

As for high rate set up that is a completely different animal and is another topic entirely.

I understand your rational behind dialing the elevator throw down to a point where it is still effective while maintaining control----- but I have dialed mined down so much that loops are absolutely huge at full input. Anything more and it will roll or snap out. I would say I can only use maybe less than 10% throw before it snaps, or whatever you want me to call it.

IME snappy planes have either too much elevator throw, the number one culprit IMO. If your loops are huge then you definately have something else going on and my next culprit would be the elevators are traveling unevenly. The ONLY way to veryify that they are in syc is to get a pair of clothes pins and CA some pushrod wire or coat hanger wire on them, about a foot long peice is usually sufficient. Clip the pins on the elevators and bring the tips of the wires close to each other and bend them till they are right next to each other. Now turn on the plane and move the elevators through their full range, the wire tips should track each other perfectly, if they don't your gonna have issues with the plane.

Next is the CG, I have found that NOSE heavy will result in a much more violent departure than a tail heavy condition will. My favorite method for checking balance is to roll inverted and let go of the sticks at about 3/4 throttle. If the nose drops and the plane heads for the ground at a steep angle your way nose heavy. If the plane climbs your way tail heavy. If the plane flies perfectly level(rare) your neutral. I prefer then to drop the nose just slightly, one or 2 clicks of down trim would get the flying a level track at the most.

After that if nothing seems to be helping you either have a model that has an incidence problem or one that is grossly over weight. Incidence is easy to check with a meter, if you really want to get it bang on(and this can make a HUGE difference in ALL of your models BTW) buy 2 meters and put one on the tail and one on the wing at the same time, compare readings between the two. Do the same on the wing panels and then on the same panel but one on the tip and the other on the root of the wing to check for warps.

Something I have done for quite a while is to set up my planes by first adjusting the radio sub trim to get the servo arms at 90 degrees to the servo case then adjust my linkages to obtain zero degrees of incidence on elevators and ailerons. You should also check up/down thrust at this time as well. After setting up the plane I fly it and usually there will only be a couple of clicks of trim required, if any at all.

Most of us tend to (eyeball) where the surfaces should rest while in the neutral position, especially the ailerons, which can result in a built-in couple of degrees of unintended posative or negative incidence. A couple of degrees doesn't sound like much but it can be the difference between a model that flies extremely well and one that has nothing but problems.

Just out of curiosity what is the span on your plane and what is the weight of the model with the tank dry?

span is 53 inches. I have no idea what the weight is. According to Ultra R/C, they fly the same set-up with saito 82 and they don't have any problems. It doesn't "feel" like its overweight while flying either.

Try increasing your expo on your ailerons and do the loop thing. You may be getting into the ailerons on the elevator imput. Its easier to do than one may think...Watch your rudder when you throttle up, you'll see what Im refering to...

53 inches is a pretty short span, it's a .46 sized plane with that span. Ideal weight for a plane that size should be no more than 5.5 lbs. and no more IMO. Remember on models of this size the ounces add up fast since they are so small to begin with. If it's at all possible to take any weight off the plane it can only help out.

I have no idea what your set up includes but if I were setting one of these up I would avoid metal geared servos, battery packs larger than 600 mah and the fuel ank should be no bigger than 10 ounces. The .82 is a pretty big engine for a plane that size and consequently brings problems of it's own to the party. Also the .82 is a torque monster and will really work a plane with that short of a span. I would be willing to be the engine mount right thrust was factored for a .46 two stroke which has much less torque and consequently isn't correct for the .82 thus requiring some fine tuning to get it right.

All the components are fairly lightweight. Battery pack is a stock hitec 600mAh 4.8V. Servos are 2 HS81s on the elevators, HS545 on the ailerons, HS605 on rudder, and futaba s3004 on throttle. Saito 82 is pretty light itself, comparable to some .46 2 strokes out there. Anyways, your point about the saito 82 being too much engine may be right, although as mentioned previously ultra r/c used the 82 in one of their planes.
Anyways, without beating this thread to death, I am probably going to try and sell the plane anyways. Thanks for all the advice.

sbaugz,
Just try it before you sell it........ Get rid of the right thrust! As you found out, moving the CG forward does not help a stall and can make it worse. An airplane should look like its falling off to the left on a full power up-line.... You can always mix in right rudder with throttle if you really need to have the straight looking upline. This is how ALL full scale and many Pattern & IMAC fliers are getting the stright up-lines. If you have so much right engine thrust built in that the airplane looks straight up in a full power upline it will be yawing to the right all the rest of the time. This is the one sure way to make the right wing drop (stall) before the left. If you still don't think it's engine thrust try this.
Take off then add a bunch of left rudder trim & then trim the ailerons for level flight. Now yank back hard on the elevator on high rates. The left wing should now stall first. A good 3d pilot can make either wing stall first or make both wings stall at the same time with Yaw (rudder) control.

Ok my input. Watch your wieght!!!!!!!. I HAD a saito 91(14x4), 2300 NIMH battery and all stock servo's and the thing snaped BAD 2 times. I crashed and ordered parts. After last crash I went back to a magnum 52 (12.25x3.75)and put a 9g servo, under the cowling for the throttel and stock battery . Also took off the wheel pants. Put one servo in tail for rudder and 3001 on elivator in normal spot. Battery is behind the tank. Also conected the elivator's -- with carbon rod I had. It still has the dual control going back to. (that I do not like.) It made its first landing last week like this. Flew a lot better. It does knife edge good no great- superb. I did one hard loop and it did seem to roll a little bit but far from a snap. I have installed a Hitec 225BB on the elivator. To save some more wieght. But I do not like the way it centers the elivator. The hitec's that I have had new and used have all centered like crude. If there is a mod to make them center better email me. I will fly it like this. Hope it makes it back in one piece. Just watch that weight. I did not like the saito 91 to heavy and to much power. This wing area is small. Also did not use the yellow man holder thing. The virtical is great with this setup. If you want a 3d plane buy something else to over power. This thing does fly good. That saito 82 is light. I would put a smaller prop on it to check it out. and a small servo on throttel. hope this helps. [email protected]