GREAT PLANES U-CAN-DO 3D .46 ARF
by Bret Ostlund
Aircraft Type: Fun Fly 3D
Mfg. By: Great Planes Model Mfg. Co., P.O. Box 9021, Champaign, Illinois 61821, Ph. (217) 398-8970, Fax (217) 398-7721; www.greatplanes.com
Mfg. Sug. Retail Price: $199.99
Available From: Retail Outlets
Wingspan: 56.75 Inches
Wing Chord: 16 Inches
Total Wing Area: 904 Sq. In.
Fuselage Length: 58.5 Inches
Stabilizer Span: 22.5 Inches
Total Stab Area: 132 Sq. In.
Mfg. Rec. Engine: .32-.50 2-stroke; .52-.70 4-stroke
Rec. Fuel Tank Size: 8 Oz.
Rec. No. of Channels: 4 (6+ Ch. recommended)
Rec. Control Functions: Rud., Elev., Throt., Ail.
Basic Materials Used In Construction: Fuselage: Balsa, Ply & Lite Ply
Wing: Balsa & Hardwood
Tail Surfaces: Balsa
Building Instructions on Plan Sheets: No
Instruction Manual: Yes (27 pages)
Const. Photos: Yes
Radio Used: Futaba 8 Ch., 6 Servos
Engine Used: O.S. FS-70 II
Fuel Tank Used: 8 Oz.
Weight, Ready to Fly: 97 Oz. (6 Lbs. 1 Oz.)
Wing Loading: 15.5 Oz./Sq. Ft.
WE LIKED THE: Ease of assembly, excellent manual, high quality construction, and great flying characteristics.
WE DIDN'T LIKE THE: Wrinkles in the MonoKote, tendency to come out tail heavy, 1/2 lb. heavier than advertised.
Great Planes has recently released the U-CAN-DO 3D .46 (UCD 46) a smaller version of the very popular original, U-CAN-DO 3D .60 (UCD 60). The U-CAN-Do's were specifically designed with the novice 3D pilot in mind. And yet, if you are a sport flier, don't let the "3D" connotation lead you to conclude that these planes are solely suited for the hair-raising, death defying, maniacal machinations you might associate with 3D flying. These planes can be as wild or mild as you please. Some of the finest flying planes produced today are designed for the "Artistic Aerobatic" events which are becoming popular these days. In essence, these planes are 2-meter FAI pattern ships matched with large control surfaces for "Freestyle" maneuvers. One could draw simi-larities to the U-CAN-DO's with two major differences. The first would be the wing design and the second would be about $1,000.00 or more.
The U-CAN-DO's combine light-weight construction, a constant chord wing, a thick symmetrical airfoil, large control surfaces and a long tail moment. The wing design and light weight allows the plane to fly very slowly, the large control surfaces are effective at slow speed, and the long tail moment provides extra stability and tracking. This extra stability has been a trade off for the UCD 60. For instance, it is not the easiest plane to flat spin. However, the payoff becomes clear when you pull up into a hover. WOW. On a calm day the UCD 60 appears to "stick" to the sky, it is the easiest plane to hover that I have flown, just pull up and park it.
I have flown the UCD 60 version and found it to be a very forgiving airplane and just a blast to fly. I surmise that the UCD 46 might fly a little closer to the "wild side" due to its smaller size. We'll see.
The U-CAN-DO 3D .46 came neatly packaged in one box measuring 13.25" x 7" x 58.5". There were no missing parts or damage to the components. The initial inspection revealed wrinkles in the MonoKote covering that would need to be ironed out. The majority of these were on the fuselage and control surfaces, the wing looked pretty good. All were in the acceptable range but there were more than I would like to see. MonoKote covering may require a little more heat for this task than covering materials used on other planes, but try not to use more heat than necessary. The fit and finish of the wood construction was well done.
I took a good look at the firewall and landing gear mounting block, two potential trouble areas. The firewall was braced from the backside with triangle stock. I couldn't tell if it was pinned or not but the landing gear mounting area was pinned with dowels and both areas looked to be solid. The covering pattern is bright and color- ful and looks good to my eye. A checkerboard pattern on the underside of the wing is a nice touch, it will be easy to tell "up from down." Control surfaces appear well proportioned and sturdy. The aluminum landing gear is painted white and feels solid. The cowl and wheel pants are made of fiberglass and are painted; both are lightweight and look great. The hardware is packaged in a plastic bag; all the nuts, bolts, wheel collars and the like. The nylon parts, clevises, wing bolts, etc., are in a separate bag. The pushrods are 2-56 with "Faslink" swing away connectors for the non-threaded ends. Foam wheels, the fuel tank and a spinner are included as well.
A number of time consuming steps have been completed for you on this plane. The engine mount blind nuts in the firewall, the wing mount plate and blind nuts, and the landing gear blind nuts, are all pre-installed. This plane is very simple to put together and assembly is made even easier with the excellent manual.
It's a good idea to read through the 27-page manual before starting. It includes a lot of tips and pictures to guide you through the assembly. The first order of business was to iron out the wrinkles; this took me approximately 45 minutes. Some of the control surfaces had a few stubborn ripples remaining, but they were minor. A one-piece wing gets the construction off to a flying start. After removing the covering from the aileron servo mounts and wing bolt holes, you will cut the CA hinge material into 1" squares. The ailerons are installed first, the hinge slots are pre-cut but may require a little cleaning up, and the procedure for the hinge installation is clearly explained in the manual. To add a little stiffness when attaching the belly pan I chose to run three 1/2" x 1/4" balsa stringers across the width of the belly pan, one in the middle and one towards each end. I removed the covering on the wing under these stringers, then used Pacer 5-minute Z-Poxy to attach them. Remember to position the belly pan as far back as possible.
Slide the horizontal stabilizer into place and make sure it aligns with the wing. Mine leaned a little to the left and a couple of swipes with a flat file along the offending edges straightened things out nicely. You will need to remove a portion of the covering on the stabilizer before gluing. I use an old butter knife that I heat up over a stove burner to cut the covering. If you try this, don't get the blade red hot and don't even think about using one of your good knives because it will discolor. I used an aliphatic glue to attach the stabilizer and vertical fin. I believe this glue is plenty strong, it cleans up with water even after it's dry, it dries clear, will not damage the covering, has no fumes, and is cost effective and lightweight. The elevators and the vertical fin are then attached followed by the rudder.
When gluing the throttle servo mount in place, be sure to leave enough space behind it for a battery pack, including foam wrapping. As noted in an included Product Improvement Sheet, the upper portion of the forward former will need to be removed to fit the fuel tank into position. This is clearly shown in the photos and is easily done.
Take note of the throttle pushrod set-up and observe the bends at the throttle arm. It looks a little strange but it works well.
You may want to reinforce the wing mount plate to prevent it from pulling loose. I am only aware of one instance of this occurring, but once is too many. The remaining assembly is straight-forward and clearly outlined in the manual.
A New O.S. FS-70 II Sur-pass was used to power the review model and provided plenty of power for 3D aerobatics.
For power, the recommended O.S. Surpass FS-70 II was selected. I am very pleased with the performance and reliability of this engine. It starts easily and has never quit in the air. I burn Cool Power 15% made with a synthetic oil blend that helps prevent nasty gum build-up. The prop that works best for me is an APC 14 x 4 wide blade. The engine manual recommends a 14 x 6; with a 6-pitch prop, throttle management will be essential to prevent excessive speed. Control surface flutter can destroy an airplane in an instant. And excessive speed and improper set-up of the control horns and linkage hardware are the major contributing factors. Selecting the proper prop is very important in order to maximize the performance of any plane and especially a small 3D type. It is worth the time and effort to find the prop that works best with your set-up and style of flying. The O.S. 70 has plenty of power at my field elevation of approximately 1,000 feet above sea level. In addition, use of this engine will help prevent a tail heavy C.G. due to its relatively high weight.
The included spinner is very small and unusable with larger props. An aluminum spinner might be your best bet, but they can be on the heavy side and may slow down the prop accel-eration, although the extra weight will be useful for balancing. Note: Your engine will have a tendency to run hot in the cowl, particularly when hovering on a hot day. Run the engine as rich as possible. Be aware that just because you see a nice smoke trail does not mean that your engine isn't overheating. If you notice a lack of power it may mean the engine is getting too hot and is sagging.
I used my Futaba Super 8 radio and a 5-cell 6v 1600 mAh NiMH battery (AA) pack. As a rule, I would use a smaller, lighter battery but I'm using digital servos and I will need the additional power. Hitec 545BB's were used for all flight controls and a Futaba 3001 was used for the throttle. With the exception of the elevator I made use of all the stock hardware. The 2-56 pushrods have performed adequately, but installing 4-40 hardware would not be a bad idea. Du-Bro heavy duty, extra length servo arms were used to provide the longer throws necessary for the 3D control travel. Use the outermost holes on the control horns. This provides the best leverage advantage over the control surface and helps prevent flutter.
The author shown putting the U-CAN-DO .46 through its paces. A very nice flying airplane!
Center of Gravity (C.G.):
The manual's recommended C.G. range is 4" to 5-1/2" from the leading edge. An addendum posted on the Great Planes web site revises this to 4" to 6". (If you have purchased any recently released kit, I would highly recommend that you check the manufacturer's web site for any revisions they many have made to the manual.) Adding to the confusion, my manual recommended a specific C.G. of 4-3/4" for the best performance. Well, with the O.S. 70 a 14 x 6 APC prop (heavy), a 5-cell 1600 mAh NiMH battery pack over the fuel tank and an aluminum spinner, it balanced at approximately 5-1/4". This was within the recommended range. However, for the purpose of this review I thought I should fly the plane at the recommended 4-3/4". The O.S. 70 is the heaviest engine recommended for this plane and it still would take several ounces of lead to balance at 4-3/4". If a lighter engine were installed, well who knows ...
At this point I made the decision to remove one of the two tail-mounted elevator servos. This would serve to lighten the plane by at least 2 oz. and correct the aft C.G. problem. I joined the elevator halves with a 2-1/2" long piece of 1/2" x 1/16" aluminum angle stock, which I trimmed flat except for a small lip of the 90% bend in the middle for added strength. A piece of carbon-fiber plate would work as well. The fuselage needed to be cut out for clearance for this. This is easy to do - just take your time and make it look as nice as you can. I also replaced the 2-56 pushrods with 4-40 hardware since one servo would now be controlling both elevators and I substituted a different control horn. Now the plane balanced at 4-3/4" with a battery pack just behind the fuel tank.
"Perfect!" I thought, smugly. But alas, after some flight-testing I concluded that 4-3/4" was too nose heavy for my preference. After relocating the battery behind the throttle servo, it again balanced at 5-1/4". At this C.G., the plane flew great. It was very stable and exhibited very little coupling but it was still a bit nose heavy for some 3D maneuvers. So now I had to add the 2.5 oz. of weight back to the tail to balance it at the aft-most recommended C.G. of 6" from the leading edge. This produced pitch-coupling problems with the rudder and made the elevator control very sensitive. On the other hand, it definitely got the plane in touch with its wild side. There was a noticeable improvement in the performance of maneuvers such as flat spins, waterfalls and general flip-flopping.
So now what? Well, I could move the battery back further in the fuselage in order to balance it at 6" for the best 3D characteristics, but this would be at the expense of the desirable tracking and precision of a forward C.G. So for now, I decided that I would simply add the 2.5 oz. to the tail when if felt like flying 3D and remove it for the precision mode. I despise adding weight to a plane, particularly after going to all that work to remove it in the first place, but due to this plane's unique capa-bilities I think that it's worth it. (Be aware that a full load of fuel changes the C.G. by almost 1/2"; as a result, the C.G. will change as you burn fuel.) The final flying weight is 6 lbs., 1 oz. less fuel and tail weight.
The intent of my C.G. ramblings is an attempt to provide you with addi-tional options and to make the point that this plane has dual personality that you may want to take advantage of. You will need to do your own experimenting to determine what works best for your style of flying (see sidebar).
Flying the Maneuvers
With the constant chord wing and the thick airfoil, I would consider this a Fun-Fly 3D plane. This plane is not going to 3D the same as an Extra 300 or Edge 540 with thinner, tapered wings. This isn't a bad thing, it's just different. This plane is marketed for its flying capabilities, so I will comment on a few particular maneuvers. These are my observations (not irrefutable facts) after over 30 flights and naturally they are subjective, in spite of my best intentions. Hopefully, I can convey some of the nuances of this plane's capability.
Take-offs are straight and easy, even with an aggressive use of the throttle. Note: if you are using a spoileron mix make sure it's off when you take off or you many not leave the ground. Landings can and should be made at a very low speed. With a forward C.G. placement, the plane will land in a 3-point attitude; with an aft C.G. the plane will tend to land in a tail low attitude. This is not a problem; it just takes a little better throttle control.
I was surprised at how axial the rolls were with the C.G. at 5-1/4". High rate rolls spin like a bullet and vertical rolls were impressive as well. With low rates it is possible to do a very nice slow roll the length of the runway. Rolling circles with 1, 2, or 4 rolls, can be flown in a very respectful manner. Rolling loops are fun to do.
Any size or shape, including inverted, rolling, knife-edge or square loops are possible.
There is very little pitch coupling with the C.G. set at 5-1/4", it does pull a little to the belly but I haven't bothered to mix it out. If the C.G. is set in the aft range the pitch coupling will be much more pronounced. Knife-edge loops are possible; however, the last 1/4 is a nailbiter as always. Slow, high alpha knife-edges are stable and easy to do. The rudder authority is excellent. With a little head wind I have been able to do what I would call a knife-edge elevator, where the plane descends with almost no forward speed. It definitely looks cool. This plane excels at knife-edge flight, with the proper C.G.
I did find it necessary to use high rates to do a flat spin. Upright flat spins spun at a nose down attitude. Inverted flat spins are better, but they still rotate nose down. These were best with the C.G. located in the aft range. For knife-edge spins use spoilerons. Blenders are possible but for your plane's sake; don't do them at full throttle from a high-speed dive.
Torque rolls and hovering are very easy to do for a plane of this size. The UCD 60 is even easier to hover simply because of the larger size. A calm day is always best for practicing Torque Rolls. In my opinion, a large diameter heavy prop helps encourage the plane to rotate. You will need to use high rates on your transmitter in order to make large corrections to prevent the plane from falling out of the hover, yet you do not want to over-control it on smaller corrections. This is where you must use exponential to soften the controls around neutral. It may feel awkward at first, but you will become comfortable with it eventually. The UCD .46 will hover at any C.G., although I preferred a 5-1/2" C.G.
I found these to be poor until I moved the C.G. to 6", then, with the help of the spoilerons, they rotated very well.
These tend to be wobbly and it's very easy to fly out of them with too much throttle. The use of 30% spoilerons did not appear to help much. Make sure that you balance your plane laterally. Harriers were easier with the C.G. at 6". If an extreme amount of spoileron, up to 100% mix or a 30 to 45° angle of the aileron is set up as a mix or on a switch, it will force the plane into a Harrier attitude and it works fairly well. I am not convinced that it is a true Harrier, but who cares. As always, experimentation can lead to surprising discoveries.
I didn't have much luck with these, even with a headwind. Like the harriers, the wing just won't stall properly. Again, as with the Harriers, with a 100% spoileron mix it will do a respectable Elevator and perform better Walls. Speaking of the wind, planes like these are a lot of fun to fly in windy conditions, it's possible to fly them "backwards" and do stationary rolls or knife-edges, and you will improve your flying skills at the same time.
Mine has been a 75 ft. (more or less) tail slide that I did one calm morning. And better yet, I was able to stop it into a hover and then fly straight back up. I'll admit that there was a little luck involved, I'm not sure I'll be able to do it again, but it can be done. Backing a tail slide down that far takes practice. You have to learn to "fly" it backwards as the control response is reversed. The sound of the prop ripping the air as it backs up is totally "wicked" particularly at the bottom when throttling up to stop the descent. The 6" C.G. is best for tail sliding.
The recommended settings were used for both low and high rates. On high rates, I use about 80% exponen-tial, on the elevator and ailerons. This is a personal preference, but you will need to use some expo on high rates or the plane will be very difficult to control. I set up a 30% spoileron mix on a switch, for both up and down elevator control; it is useful for some maneuvers. I would recommend that you experiment with different per-centages and determine what works best for you.
One more thing that will have a profound effect on the performance of your plane is weight. A .40 size 3D/Fun-fly cannot be built too lightly in my opinion. At some point, for comparison purposes, I intend to remove the cowl and the wheel pants, put on a wood prop, and remove the spinner. I may experiment with a smaller battery and only partially filling the fuel tank and use a mini-servo for the throttle. These are extreme measures, generally reserved for the obsessed among us; just suffice it to say that you need to keep it as light as possible. Be aware that metal gear servos, NiCd batteries, aluminum spinners, and pilot figures are heavy.
With low rate settings on the controls, the average sport pilot could have a lot of fun with this plane. Its forgiving nature and excellent flying characteristics will inspire the confi-dence to improve your flying skills and push your limits. And when you feel really brave, move the C.G. back, crank up those throws and get busy.
The UCD .46 is not going to replace your pattern ship, but this is the best flying constant chord wing plane that I have flown. With power to spare for up lines and verticals combined with impressive tracking and stability at a forward C.G., she aims to please. Use high rate ailerons for simulated snap rolls. Rolls are very axial. Knife-edges have very little pitch coupling. Vertical point rolls always impress me. If nothing else, you can amuse yourself attempting the maneuvers in-between your 3D session.
Gentle reader, trust me, if you are interested in this type of plane I simply cannot imagine how you could be disappointed with a U-CAN-DO 3D .46. with the caveat that you use an O.S. FS-70 II, an APC 14 x 4 wide-blade prop and good servos (analog or digital). To simplify things for you, I would suggest a 2" aluminum spinner and placing the battery pack over the fuel tank. Your plane should balance in the 5" to 5-1/2" range with both elevator servos installed. This set-up will get you in the air as hassle-free as possible. As your flying skills improve you can fine-tune it as necessary. Other set-ups may work as well or better. I simply cannot comment on them because I have no experience with them.
You already know that anything less than a 40% airplane is a compromise. This plane is probably not the full-blown 3D monster of your dreams. With that being said, the UCD .46 could easily become one of your everyday fliers.
One would be hard-pressed to find more all-around performance in a .40 size airplane than the U-CAN-DO 3D .46. This plane has surpassed all my expectations and no one is more surprised than me. With high rates and a 6" C.G., the UCD .46 will 3D with aplomb. For a reasonable pattern ship impersonation, use low rates and a forward C.G. It is predictable, stable, well-built, and an excellent value. It looks great and most importantly, it is fun and rewarding to fly.
Photos by Bret Ostlund. Reprinted with permission.
January, 2004 R/C Modeler Magazine
Editor: Patricia Crews