RCU Review: NitroModels Ultimate Bipe 40

Review by: Jason Buzzeo (Buzz390916) E-mail Me



Nitro Model Planes
PO Box 3382
Alhambra, CA 91803
Phone: 626-261-4960
Fax: 626-628-3388



Window Media Player
Nitro Models
Ultimate 40




Ease of Assembly:
Completeness of Kit:
Covering Quality:
Basic Flight:
Advanced Flight:
Stall Characteristics:
Score: 7.7


  • Very Complete
  • No External Servos
  • No "Extra" Servos
  • Excellent Flight Characteristics!
  • Perfect fit for .40 powerplant left over from your first trainer!


  • Sloppy Parts Fit.
  • Very Limited Instructions.
  • Hardware Issues (see text).



In an effort to make a great airplane even better, Gordon Price and the Ultimate Aircraft Company began modifications to the Pitts Special in 1977 - 1978. The goal?? Make an airplane as versatile as the Pitts, with added performance that's aesthetically appealing. After the wing, canopy, fuselage and wheel pants had all been re-designed; the only logical decision was just to build a whole new aircraft. And thus, the Ultimate Biplane was born.

10 Dash 200

The Ultimate has been a favorite of R/C enthusiasts (especially myself) for quite some time and now NitroModels brings it to us in a .40 sized ARF, with a beautiful color scheme and an affordable $125.00 price tag.

Upon opening the box, I was very surprised at how small this airplane was. Immediately, I became adventurous as to how small of an engine I could put in her. The good news is, for all of you who have a bushed .40 -- such as the OS .40LA -- This turns out to be the ideal size.

So, without further ado, let's take a look!!



Name: NitroModels Yellow Ultimate 46

Price: $125.00 ($395.00 msrp)

Wingspan: 43.5 in / 1100 mm

Wing area: 580 sq in / 37.5 sq dm

Weight per Mfg: 4.5 lbs. / 2050 g

Skill level: Intermediate - Advanced

Radio Used: JR 6102FM Tx / JR R700 Rx
(4) JR NES-537 Servos for Throttle, Ailerons
Elevator, Rudder

Channels Used: 4 Total - Elevator, Aileron, Rudder, Throttle

Engine & Prop Used: OS MAX-.40LA - MA 10x6


Required to Complete:

  • 4 channel radio with 4 Servos
  • CA glue
  • 30-Min epoxy
  • .40-.46 2-stroke; .56-.82 4-stroke Engine, w/ Propeller & Spinner
  • Standard building tools



I was a little surprised when I opened the outer shipping box and a bag of hardware fell out. I'm really not sure why it wasn't in the actual packaging, but as long as I got it, there's no reason to complain. Just goes to show how important it is to make sure all boxes are empty before you throw them out.

Inside the actual box is very impressing. Every piece is individually wrapped in plastic, and any protruding metal pieces are covered in Styrofoam to prevent them from puncturing the covering -- or worse yet -- the wood itself during shipment. Removing both wings and the tail feathers exposes a cardboard divider that when removed reveals the remaining parts packed in individual compartments.

As for the pieces themselves, they look great!! Good solid construction and, the covering is beautiful. Now let's wade through the manual and see if we can get this bird in the air by lunchtime!!



The eight page flyer provided as a manual leaves much to be desired. While every major step in the process is included, the actual instructions are not. Each step is represented by a picture of the materials and a set of ambiguous icons representing cuts to be made, hinges to be glued, tab/slot fittings, etc. However, there is no key for the icons, so you're left to your own resources to decipher their meanings.

In a few cases, the photos are accompanied by a single sentence of instruction which appears to have been added to the original image before it was enlarged for the manual making everything blurry and the smaller text almost impossible to read. The good news is that the Nitro Models Ultimate came out of the box with so little construction necessary, that the lack of detail in the manual was not really an issue, and if you're working on an aircraft of this skill level, then you should have little trouble with this beautiful model.



Pretty basic stuff, both wings come out of the box in one piece. The surfaces are already slotted with hinges and control rods installed, so just "Zap" the aileron hinges in place, screw on the control horns, and cut out covering around the servo mounting hole in the top wing.

All that's needed for now is to hinge the two ailerons, install the servo, install Control Horns, and hook up the pushrods. While the manual made no mention of it, the box showed that 4 micro servos were to be used. However, all of the pre cut servo trays are cut for standard servos, so I went with them instead. I did have to remove more of the center rib, but a smaller servo would not have been long enough to fit on the mounting bracket.



The tail feathers come out of the box pre-slotted with hinges & control surfaces in place. There was plenty of play in the hinge slots, so it was easy to make sure everything was well centered before securing it all in place with a little thin Zap.

*Note: DO NOT secure the bottom rudder hinge in place at this time. This hinge will be secured into the slot provided in the rear of the fuselage later.

As for mounting, there are three pre-cut slots in the aft section of the fuselage - two on each side and one on the top. The covering around each of the three slots has already been removed. Both the horizontal stabilizer and the fin were a little bit of a sloppy fit, but I'd rather have room to make sure everything is straight and level than have a tight fit that leaves your tailfeathers warped. Remove the covering from the center of the stab and epoxy into place, repeat for the fin which rests on top of the stab, making sure not to forget the final rudder hinge. Left over gaps were easily filled with a little extra epoxy.

Once the epoxy cures, all that's left is to mount the control horns and tail wheel. The tail wheel assembly needs to be put together, and since there were no instructions and no mounting hardware, I bent the end of the wire down, and drilled a hole in the rudder in order to attach them.




Assembling the wheels and wheel pants was no easy feat. First I tried to assemble them based on the manual, but soon found this to be an unattainable goal. Instead I came at the gear from the completely opposite angle, proving not only to be easier, but also more realistic. Their instruction included sandwiching the landing gear and wheel pant between a bolt head, and a nut & washer. Unfortunately, the provided bolts had no threads on the last 1/4" making it impossible to adequately tighten the bolt against the wheel pant. Once completed I bolted the main gear to the fuse using the provided landing gear bolts and pre-installed blind nuts.

The manual also showed a small screw going through the main landing gear and into the wheel pant to hold it in place. Since there was no hole in the landing gear for this, nor were there two extra screws, I skipped this step. The result was having the wheel pants break loose on the maiden flight, so I just removed them all together, as can be seen on the video.

Their Way

My Way


The engine mount also took a little ingenuity. The manual showed the installation for a 1-piece engine mount, which this was not, and instructs you to bolt the mount to the firewall using the supplied engine mount bolts and the pre-installed blindnuts. As I proceeded, hoping that my chosen engine would fit, I noticed that while the blind nuts were provided (two in the bag of hardware, and two in the bag that fell out of the shipping box), they were not installed, nor were there holes in either the firewall or the engine mount.

The firewall has a horizontal and vertical line drawn through it, just off center; I used these to line up the engine. Using a little thin Zap, I tacked the engine to the mounts to insure proper spacing, lined up the mounts and drilled 4 holes through both the mount as well as the firewall. To install blindnuts, I like to hold them with a screwdriver, it makes them easier to position into the mounting holes. A little thin Zap insures they stay where you put them until the screw tension can pull their "teeth" into place, and a quick rap with a hammer also helps to get the "teeth" started. One more advantage of the screwdriver method is that it gives you a nice hammering surface since getting to the actual blindnut would be almost impossible.

Bolt on the engine and assemble the fuel tank. There is no room to pad the tank with foam rubber, but the tank fits so beautifully into the provided bulkhead cut-out that I didn't feel this was necessary, and since the instructions made no mention of it, I decided it was ok the way it was. You do, however, need to secure the tank in place by gluing a piece of scrap wood (not provided) just behind the tank to keep it from moving backwards during flight.

OS 40LA Closer Look
O.S. 40LA

The standard in sport engine technology, in a unique streamlined design


  • Stock Numbers: OSMG0040 (Blue) and OSMG0041 (Natural)
  • Displacement: 0.3963 cu in (6.49 cc)
  • Bore: 0.8346 in (21.2 mm)
  • Stroke: 0.7266 in (18.4 mm)
  • Practical rpm: 2,000-16,000
  • Output: 1.0 hp @ 16,000 rpm
  • Weight: 9.5 oz (269 g)
  • Recommended Propellers: 10x6.5, 10.5x5-6, 11x5-6

Per the recommendation above I used a Master Airscrew 10x6 Prop.

The O.S. .40LA replaces the .40 FP as a sport airplane engine. This is a non-ring type engine and is available in two finishes; anodized dark blue and the natural aluminum. I picked up the blue one because it was the only one available at the time, but the aluminum finish is less expensive, and the finish is purely a cosmetic feature, so unless it fits your color scheme somehow, save your money and pick up the natural finish.

Instead of having a needle valve shooting out of the carbourator, the 40LA comes equiped with a remote high speed mixture adjustment. Mounted on the back of the engine, this handy feature lets you adjust your needl valve without getting too close to the spinning prop. Remarkably, this engine is very affordable, you can pick one up for right around $60.00, less if you do some shopping around. Unfortunately, instead of having twin needles, the 40LA comes equipped with an air bleed carb. My guess is, this is to help keep the costs down. Because if this, I found it very difficult to start this engine by hand, even when it was "warm" it took a second or two with the electric starter to get her to turn over on her own.

Download the manual in PDF format - Click here

With the engine mounted, drill a hole in the firewall for the throttle pushrod. Bends needed to be made in the pushrod, as there is little room to get the pushrod through the bulkheads and to the servo tray. In hindsight, it may be possible to avoid this dilemma by mounting the engine sideways or inverted.

After installing the throttle servo, I attached the throttle pushrod. The manual suggests using a "Z"-Bend, but I find the Du-Bro ball connector to be a worth while substitute.

I had to cut a pretty nice sized hole in the cowl to allow for the muffler, so I didn't bother cutting out the bottom for extra airflow. I also made a slit in the bottom of the cowl and mounted it using two extra screws in the bottom to allow the cowl to slip around the muffler and propeller, rather than having to remove them every time the cowl has to come off. Because I chose to mount the engine up-right, a considerable portion of the front had to be cut away to allow air into the carburetor.

All that's left now is to attach the fuel lines, mount the cowl and attach the spinner and prop.



Mounting the top wing proved to be a bit tricky. The manual said to position the wing using the provided incidence jigs, but much to my dismay, there were no such jigs in the box. Instead I chose to mount the wing struts and use them in place of the jigs. The struts made a good tight fit, so I assumed that this would make for an acceptable alignment. With the cabanes mounted to the top wing and the wing held in place by the struts, mark and drill pilot holes, then screw the cabanes into place.

Now that both wings are mounted, the control rods can be added to connect the upper and lower ailerons. The manual mentions predrilled holes for the control horn locations, but there were none. This happened several other times throughout construction, but as in this case, it was never a big deal.

With all the major assembly complete, it was time to install the radio. Servo installation was a breeze, and I was very pleased to see that all of the servos were mounted internally with pre-installed tubes for the rudder and elevator pushrods. Also, the elevator pushrod was already assembled, however, the manual shows a picture at one point of a piece of hardware being used to spread the wires at the "Y" split, but I found no such piece of hardware. The good news is, I didn't really need it.

As for the switch, it was mounted using a DuBro Switch Charging Jack. If you've ever used these, you know how nice they are to have. If you haven't, do yourself a favor and get some. You won't be disappointed.


Take off was beautiful, the OS .40LA is the perfect engine for this plane. Minor trimming was required, but certainly no more than normal, and now it was time to see what she could do.

I will not tell you that this is an easy, or trouble free airplane to assemble. But, what I will tell you is that all of the headaches you may experience during the construction phase will completely vanish the minute you take to the air with this beautiful bird. NitroModels Ultimate is one of the best flying airplanes I've flown in a long time. It flies fast, it flies slowly, and it flies upside-down & sideways.

Take a look at some video of the Ultimate Bipe in action.


Ultimate 40 Video -
.WMV format; 7.5 Mb


The only complaint that I have (Aside from the Manual) is that the aileron control arms are extremely long with no way to adjust the control horn, so she has a very slow roll rate. I replaced the servo arm with the longest one I could find to add extra throw, but it's still not "zippy" by any means. But don't let this deter you, it's still a great little airplane that I have thoroughly enjoyed flying. If you're looking for a good flying bipe, and especially if you have an old .40 laying around that you haven't been able to use since your first solo -- pick up this plane! You'll be glad you did!!

Till next time, keep your eyes up, your wings level, and your hand out of the prop!


Nitro Model Planes
PO Box 3382
Alhambra, CA 91803
Phone: 626-261-4960
Fax: 626-628-3388
Website: www.nitroplanes.com

O.S. Engines
Distributed Exclusively in the U.S.A., Canada and Mexico by:
Great Planes Model Distributors
P.O. Box 9021; Champaign, IL 61826-9021
Website: www.osengines.com

JR Radios
Distributed through Horizon Hobby.
4105 Fieldstone Rd.
Champaign, IL 61822
Phone: (217) 352-1913

Everything For The R/C Hobbyist
Phone: 1-800-848-9411
Website: www.dubro.com