Great Planes Ultimate Biplane 1.60 ARF



I have always loved Ultimates. They just look awesome with sleek profile and wedge shaped cowl. And two wings just somehow are easier on the eye in the sky and on the ground. Of the few I’ve flown, I’ve found them all to be a pleasure to fly and that’s really what we’re after right? Well Great Planes has released the Ultimate 1.60 designed for 1.60 glow or 43cc gas… A top end glow machine or perfect entry level gasser. With a projected weight of under 15 lbs, I was VERY excited to build one. Let’s see how it went.



Kit Name: Performance Series Ultimate 1.60
Price: $399.99
Wingspan: 65″
Length: 72″
Flying Weight : 14.75 lbs
Engine Used: Fuji Imvac BT-43 EI
Prop: ZM 22×10
Transmitter: Futaba 9CAP
Receiver: Futaba R138DP 8 channel PCM
(6) Futaba S9451 Coreless Digital, 4 on Ailerons, 2 on elevators, (1) HiTec HS-5955TG for rudder, (1) Futaba S9602 Coreless Mini (throttle)
Battery: 4800 Mah Lion pack on receiver -730 Mah NiMh on ignition
Channels/Mixing Used: Ailerons split in channels 1 & 6, Elevators split in channels 2 & 7
Manufacturer: Great Planes



Beautiful construction
Quality materials
Complete kit with spinner
Excellent performer

Spinner needs fitting

Foam tailwheel needs replaced


Opening the carton of the Ultimate found it nicely packed and neatly organized. When it was all out of the box, I found a quality ARF and nice hardware including a polished spinner. The first step was to iron the covering. While it arrive in fairly decent shape, there was a great deal of small wrinkles that needed attending to. And in some cases I found that during installation, the covering wasn’t pulled as tight as it could be, and therefore getting some wrinkles took a good deal of attention. Still when complete, it was a slick looking aircraft. I continued on with fuse preparation by cutting out the servo bays with an “X” and ironing the excess into the wing. This is better than trimming the covering flush with the opening as it keeps the covering from coming loose and maintains a finished look.



I continued on ironing all the openings only stopping to admire the construction in the fuse. The glue looks like epoxy and not a hotmelt type. Then I moved on tot he stab slot. First I ironed the excess into the slot.



Then I trimmed the excess to within 1/16″ of the edge. This makes sure the stab has plenty of surface to be glued to. The fin slot was treated the same. Next the hinge slots have a bit of covering around them removed. Some people skip this step, but I wouldn’t advise it. If you leave the covering as is, it can deflect some CA from going into the slot and make for a weaker hinge attachment.



Next I installed servos and aligned the horns. I like to go by the servo side as a guide to help make sure each horn is placed as close to identical as possible. Anywhere where hidden exits were found, I used a cheap soldering iron to melt the covering away. It seals it very nicely to the edge and holds tight. Extensions are tied with the pull threads and the knot has a single drop of CA applied. Don’t want them coming apart in the air right?


To finish the hinging, a hole is drilled in the center of the hingeslot. Do not skip this step either as this creates a channel by which the CA can wick to the rear of the hinge and fully saturate the hinge and surrounding balsa. Finally the drilled holes for the servos and horn are hardened with a few drops of CA. Again a step that is necessary to prevent screws from backing out. The lower wing is assembled next and the pic shows the joiner that is inside the wing.



I pinned the front and back edges to make sure they mated well and installed the front two pins while the epoxy setup. Then I located the hold down plate locations and removed the covering with the soldering iron. This really is the best and least damaging method of removing covering from areas in which you need to access or glue. A razor knife runs the risk of cutting into the sheeting and therefore weakening the surface significantly. It was time to move on to the cabanes, and I made use of a neat little tool I made from a broken antenna with a rare earth magnet glued to the tip. It holds screws in places a hand can’t go.


Instead of using blind nuts, I used washers and nylon locknuts instead. Now to the upper wing. It’s joined similar to the lower wing but with the addition of an aluminum center rib. At first I was leery of this idea, but the center rib has a rough texture to take epoxy, and when it was all said and done, proved very strong. Now the bellypan location is marked, covering removed and glued in place.



The stab is now placed, aligned and glued in place, making sure it is square to the fuse and parallel to the wings. The gear is bolted on too. There have been only a couple reports of the gear having a problem with delaminating, but also just as many have stated they have had no problems. I too found no issues with the gear as of yet, but will keep my eye on them just in case. Great Planes will gladly replace them at no cost, or you can also check with GraphTech RC and TNT Landing gear who already have made replacement sets ( both 1″ taller for you electric conversion fans). I don’t think you’ll have any problems, but keep an eye on them none the less, should you notice any cracking or separation, contact Great Planes right away. I went ahead and installed the wheels and pants too. I like the fact that the plane already has blindnuts and holes pre-drilled and assembled and installing the pants was as easy as installing two screws. A neat carrying handle was supplied and several plate are just glued together. This handle sits on the cabanes and a couple screws holds it in place and makes for a very convenient method of transporting the fuse.



I aligned the stabs control horns to point to the servos arms. The pic shows a dashed line where the hardwood plate resides under the covering. The tailwheel is now installed. This was the only area I felt required a change. The stock tailwheel was foam and went flat with a bare airframe in seconds. So I traded it out for a solid rubber tailwheel from Great Planes. Added only .2 oz. and really is a must. The Ultimate’s tail features a very unique and easy to install tailbrace setup. It uses compression retainers so a nutdriver is used to push it on the underside and I used a fender washer on top to give me more room to push against.



It’s time I jumped to the cockpit and canopy. It comes unpainted and needs to be masked and painted… I used a spray can of black paint. Then I used some lacquer thinner and a paper towel to remove any overspray and make a nice clean edge on the cockpit. I tried a different method than I usually do on the canopy. First I placed masking tape on the fuse and canopy at the center front and rear. I aligned the canopy where I wanted it and marked the tape with a matching line that could be realigned later. I then placed double sides tape on the each flat side of the canopy and placed in back on the marks. The double sided tape help fast and I could remove my masking tape.



Finally I had some matching vinyl that I cut strips out of and simply taped a seam around the canopy. Made for a very nice clean and almost seamless install. I like this method a lot and will try and use it whenever matching vinyl is available. I also have a pro vinyl cutter and converted the GP Ultimate logo used in advertising to something I can cut. I also selected some “bling” vinyl also known as holographic film and made flares for the wings and stabs. Turned out nice if I do say so myself. If you are interested, contact me via the e-mail above to find out how to get some of your own.



Using the supplied template, I taped it to the firewall and drilled for 10/32 engine bolts. I bolted the Fuji 43 on with the supplied aluminum spacers and nylon locknuts. For a tank, I decided to pass on the stock tank as it’s pretty large (about 18 oz. which is good for glow, but a lot for a gas engine this size) and chose a Dubro 14 oz. tank. I also don’t care for the rubber band hold down method employed by GP and instead created a tank floor plate. It has double sided velcro straps that go around it, a 1/4″ foam rubber pad and even two strips of velcro on the tank. It was then glued in place and ends up being right on the CG. The straps interlock with the tank and provide a very sturdy but vibration resistant mount that allows for easy removal of the tank.



I glued a couple 1/8″ aircraft ply rails into the side cubby area for the throttle servo, and used nyrod for linkage. There is a holder epoxied to the firewall to hold the end close to the throttle arm. I cut a little notch out to make for more gluing area.



The ignition module was padded and zip tied to the engine box side. I prefer to isolate it from vibration a little rather than nard screwing it to the side with the built in tabs. Taking my time I carefully marked the cowl where the engine and muffler hit the bottom. Always take a little off at a time and recheck… and remember that initially where it hits will be further back as the cowl slides on, so leave a little on the rear of the cutout til you know where it finally rests. I also have a new product of my own I am bringing to market called FIberFinish… it’s an edging that slips over the edge of the fiberglass cutout and creates a nice finished look while protecting the edge from chipping. I also pulled a piece of nyrod through the front of the cowl for the choke.



Five cowl blocks must now be located. Here the manual was a little vague in the best method of doing so. Mark the location of the block and sand the area to make for better adhesion. Then epoxy the block in place. I find it best to smear a thin coat on both surfaces as this seems to make for a better adhesion too.



Then I drilled 2 1/8″ holes though the blocks and firewall and epoxied pins in place. This will ensure that the cowl blocks don’t vibrate loose. I also pinned the firewall at this time too. To mount the cowl I use strips of stiff plastic with holes in the ends. I tape them to the fuse with the hole directly over where the center of the cowl blocks. Then using the spinner template ( a real nice touch by the way) placed the cowl on and drilled pilot holes. I also epoxied CA hinge material (you have some leftover) to the inside of the cowl where the holes were. This will help keep the fiberglass from vibrating the holes larger. Finally I used 8/32 nylon screws to mount the cowl and simply tapped the cowl blocks for 8/32. I find that these do a better job of holding the cowl firmly.



Jumping back to the tank, I soldered DuBro fuel line barbs onto the brass tubing and attached all Tygon tubing with zip ties. With the tank in place, I created a mounting plate for the receiver and regulator. I also installed a Smart-Fly Ignition Cutoff Switch… I love these things and won’t build a gas plane without one. The vent line for the tank is held in place with half a nose wheel bearing, and the ignition switch installed on a plate beside.



Here a shot of the other end of the Ignition cutoff can be seen. BTW, the ignition battery used was a 730mah 4 cell NiMH and was padded and attached to the engine box side opposite the ignition. Lastly I cutoff some Earnst charge receptacles as suggested by the manual to make for nice aileron lead ports for the top wing. That’s it… this plane is done!

I did want to take a minute and talk about the engine. I used the Fuji Imvac 43cc which is the suggested gas engine. This is a nice engine at a great price that includes the ignition, spark plug, muffler and two different prop bolts. It weighs approximately 4 lbs all up and I used a ZM 20×10 Carbon Fiber prop. It spun this prop at almost 7000 rpms and ran like a champ. When fuel was pumped to reach the carb, it took about 3 flips choked to get it to pop and 4 flips for it to start unchoked. Every single subsequent warm start thereafter was once flip. Excellent.

The needles were close from the factory and needed only slight leaning and the transition and midrange were very nice. I used Opti2 oil at 50:1 which is similar to what they recommend with their own brand synthetic oil. After break-in the recommend a 100:1 mix (even a 150:1 mix of their oil in a well ventilated or uncowled install!) At any rate, for the price of admission, this engine really delivers and made for an excellent overall match for the Ultimate 1.60.




I anxiously awaited a day that offered the best conditions for test flights, and such a day arrived in the middle of January… VERY unusual for Ohio. I ended up with partially cloudy skies, 3-5 mph winds and about 37 degree temps.

I called mu buddy to video and met him at the field.

Field assembly of the Ultimate was pretty quick… those thumbscrews are a real smart idea and help minimize the extra work required to assemble a bipe. Add to that the fact that the design requires no flying wires and this thing goes together faster than a .40 size bipe.

I primed the engine and flipped just a few times to get it started. Then I performed a range test which passed without any problems. I must admit that this is one of the few gas planes with the antenna inside the fuse that I didn’t have some limited range.  For this reason I mostly will run the antenna out the top of the turtledeck and string to the fin.

I lined the plane on the runway and give her throttle. The Ultimate offered good ground handling without much steering correction needed and in very little time the tail was up and so followed the plane. I immediately put two clicks of aileron trim in but found it to be a breeze as when I turned around, I took it back out. A click of elevator and rudder was all that was required for hands off flight. I found the stock CG very conservative for my tastes as inverted required a decent bit of down elevator.

Basic flight maneuvers were a cinch as this plane, as the old saying goes, flew like it was on rails. The Fuji 43 pulled it quite well though the IMAC and sportflying maneuvers and could hover it, but without much left for pullout.  Still the engine was only on it’s 2nd tank and with prop size I don’t think matched the powerband the best.

This plane will snap like nobodies business and stop fairly quickly upon neutralizing the sticks. It wants to flatspin both ways too, but I again the CG will have to travel rearward to flatten them out.

It’s simply a wonderful performing plane and is a joy to fly. It feels very light in the air and looks really good too! This is bound to be a very popular airframe in the coming years.

As an avid 3D’er myself, I would want the power of a 50cc engine, which would provide some radical power… this is outside of Great Plane’s recommended engine size, but they weigh about the same as the Fuji 43 and in the hands of an experienced pilot with proper throttle management should prove an awesome setup.

Still yet, the Fuji 43 when in combination with the Ultimate is an excellent value, perhaps the best to be had on the market, and sport flyers and IMAC guys would be VERY satisfied with performance.






The Fuji 43 is a nice match for this plane with regards to IMAC and general flying. It’s crisp and smooth. It also have enough umph to do some basic 3D, but real 3D enthusiasts will yearn for more power… there will be a lot of 50’s on this plane… and it can handle the weight as it’s very light in the air.

I think 50 installers will have to be conservative with the throttle however… I would not be full boring the sky unless you want to leave a trail of balsa. Not because the plane isn’t built well, but because a 50 can easily take this 14.5-15 lb. gasser beyond normal speed limits.

Still, those that put a 50 on it are doing it because they need that “WOW” power and should know to respect it.

The 20×10 ZM prop is a nice match for the engine and airframe but again for IMAC… it’s fast and doesn’t slow down as much. For instance, full idle down approaches were zero throttle and still pretty fast. Some of that was due to a high idle speed on a new, rich running engine. After a while I was able to dial down the idle and it came in slow and sweet and even needed that blip of throttle I am accustomed to with bipe.

For 3D and perhaps most general flying, I’d recommend a 20×8 MSC… it should slow down better and provide a littler better low end response.

I think overall that when it breaks in and gets a few more hundred rpm and a 20×8 prop that the performance will be very nice… as is, it crawls out of a hover and that’s just not the power 3D guys are gonna want. Again, the Fuji 43 is a sweetheart of an engine running flawlessly and still having a decent midrange running rich on both ends. A sport flier wanting speed and plenty of power for big loops will LOVE the combination and even more so the combo price. You can’t go wrong.

It does in fact have the coupling in knife edge you might expect from most planes… A slight roll to the top wing and a little more pull to the gear. Easily mixed out by hand or radio mixing.

The recommended CG is pretty conservative… and I feel you can go back a good bit… 1/2″ increments should not get you in any trouble. As set stock it drops a good bit inverted at anything other than higher speeds.

I snapped this thing hard several times…. I really half expected to see the wings give out, and in reality, was trying. Flat spins are pretty nice though with the stock CG the nose wanted to drop more inverted. And it does lose altitude quickly… I think here we see the greatest difference between the biplane and the monowing as whatever wing is on top in the spin isn’t catching much wind… thus the much faster descent.

It’s very well behaved coming out of any maneuver and simply dropping the nose is all that is needed to get it flying again.

I did a pretty hard slam-into elevator and got a lot of wingrock… It felt pretty washy in the maneuver as the surfaces just didn’t have much authority. I think some of this is due to the conservative CG and a small amount due to prop performance at low rpm… Again a wider prop like the MSC might wake it up a good deal here. It really is amazing how a prop design, brand and size change can make.

Ailerons are VERY authoritative…. you can roll blindingly fast on full rate, and even low rates are no slouch… I’d bet most will dial down the ailerons a bit.

I had elevators set to 25 and 45 degrees for lo and hi… Lo was a little too low for me and I’ll bump them to maybe 35% with a little more expo… I can’t get much more than 45 with my linkage setup, but it seemed PLENTY.

Rudder on full rate will do some funky coupling tricks… this is pretty much par for the course and needs set back till it’s the most powerful without undue coupling.

I did a blender or two, some flatspins, most of the IMAC maneuvers including some really smashing snaps… and it did it all without making a noise… you know… pop, crack or kaboom. I didn’t really expect any, but you never know and I always cringe the first time I stress the airframe in a new maneuver.

I’m not completely sure it’s an all out 3D plane… as there are many specialty planes out there that have design elements that allow for stall speed stability. However, for an all around plane and IMAC tune up… It’s a real thumbs up, especially when you consider the value. It’s perhaps the best value for entry level gas you can find.

To break it down:

If you are a Sunday flier – this will be your favorite plane
If you are into IMAC and some mild 3D, you can’t beat the value/performance combination
If you are new to 3D and want to find a good 3D trainer, keep looking, there are planes that are better to learn on.
If you are a seasoned, hardcore 3D’er… strap a 50cc engine on her and let her rip.

If you simply love Ultimates… this one has the lines, the quality, the performance and the value to become your next project.





Great Planes Model Distributors
P.O. Box 9021
Champaign, IL 61826-9021
Phone: 217-398-3630
Fax: 217-398-0008

Fuji Imvac Engine
Distributed by Great Planes
P.O. Box 9021
Champaign, IL 61826-9021
Phone: 217-398-3630
Fax: 217-398-0008

Futaba Corporation of America
Distributed Exclusively in the U.S.A., Canada and Mexico by:
Great Planes Model Distributors
P.O. Box 9021; Champaign, IL 61826-9021
Products used: Futaba 9CAP transmitter, R138DP PCM Receiver, Digital & Coreless servos
Quest Engineering & Development
1328 East Cottonwood Lane
Phoenix, AZ 85048
(480) 460-2652
Products used: Regulator with Failsafe Switch, Ignition Cutoff
HiTec RCD USA, Inc.
12115 Paine St.
Poway CA, 92064
TEL 858-748-6948
Products used: HS-5955 servo



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