Tower Hobbies Ultimate Bipe GP/EP ARF – Build and Flight Review.
The Ultimate Bipe from Tower Hobbies is certain to turn heads with it’s bright red and yellow color scheme!
Early in the flight season this year I was certain I wanted to add a biplane to my ever growing fleet of radio controlled planes. When I saw that Tower Hobbies was going to release an Ultimate Bipe in a 45″ wing span I was certainly interested. Having had good experience with Tower Products in the past (Kaos 40) I was certain this would also be a quality product – and deliver a quality product they did!
I decided to purchase the kit after Tower Hobbies had this particular ARF on sale. I decided to outfit the plane with their recommended equipment: Rimefire 55 Motor, 16×6 or 16×8 prop, Castle Creations ESC, and the Tactic TS25 Servos.
The ARF arrived packaged very well and every part was wrapped in the usual plastic bags secured with tape in the shipping container. I removed each part one by one and inspected it by hand looking for any defects or broken pieces. Everything looked perfect. The covering was done very well and only a minor wrinkle here or there was found.
The Tower Hobbies Ultimate Bipe comes with an easy to follow and heavily illustrated instruction manual. Starting with the wings, you have the option to use either two or four servos for the ailerons in the wings. I opted to go the four servo route (for my particular setup I used an eight channel receiver) since my radio allows me to setup the necessary mix to operate this many servos each on their own channel.
If you are using four servos, the manual provides directions on where to cut the covering on the top wing to allow you to install the additional servos. The kit also includes two extra servo mounting plates for this purpose. The kit also came with enough hardwood servo mounting blocks for the extra servos. I cut the blocks down slightly for a better fit and then one by one mounted them to their plates using thick CA. I drew a reference line with a pencil to help ensure accurate positioning of the servos. This is a tedious step so it is best not to rush this process!
Once the servos are mounted, the servo wires and any extensions you’ll need can be routed through the wing with the provided guide string already built into the wing from the factory. (NOTE: In the photos it shows I used a servo extension, later I removed these extensions in favor of a direct solder connection… to help reduce any possible fail points within the wire.)
With the servos completed and installed in the wings, mount the bottom wing to fuselage. The bottom wing is used for alignment of the horizontal stabilizer. Fitting the stabilizer requires centering it left to right and making sure it’s parallel to the bottom wing. Follow the direction in the manual to align the stabilizer front to back. Only minor sanding should be required to get the alignment perfect. Once that is in place I used 30 minute epoxy to secure it to the fuse. Don’t forget the elevator joiner wire should be put in place at this time as well!
Next, the vertical stab is installed in the pre-cut slot provided in the fuselage. Use 30 minute epoxy and secure in place while it dries.
Another nice touch with this ARF kit, is that the ailerons come pre-glued to the wing and the hinge slots are already cut for the elevator and rudder!
Once the horizontal and vertical stabilizers are in place, you can install the elevator and rudder control surfaces using the provide CA hinges. With the pre-cut hinge slots everything should fit together nicely!
At this point, the build really starts to progress quickly! With all of the control surfaces glued in place you are now ready to install the motor and ESC. In the back of the manual they provide a drilling template for the Rimfire 55 motor and instructions on where to mount the Castle Creations 75 amp ESC to the motor box. For the ESC you’ll have to make a battery lead extension. I added a few inches to the recommended length in the manual to make connecting the battery a little easier to handle.
Another nice touch with the Tower Hobbies Ultimate Bipe is the battery mounting plate included with the kit. This battery plate bolts in place with a single 1/4-20 bolt and blind nut. This makes battery changes and getting the CG in the same place during battery changes much easier! Tower certainly receives an A+ for that handy little feature!
Next, you can begin mounting the servos for the rudder and elevator. Controls rods are provided with the kit. You’ll have to locate the exit holes and make a small slit in the covering for the control rod exits. Be sure to consult the manual for which side is for the elevator and which side is for the rudder since they are in slightly different locations. While mounting the rudder and elevator servos you will be working on the plane upside down. (NOTE in the manual they include an addendum instructing you to install some filler wood strips because the servo slots are a little too wide.)
With all the servos in place you can now install the servo control horns if you have not already done so. There is a hard ply mounting location for the control horns in each aileron which I was pleasantly surprised to see! Harden the screw holes with thin CA.
With the plane nearly finished at this point I moved on to mounting the canopy. One thing I didn’t like about the canopy was the noticeable gap at the front where it mounted to the removable hatch. I created a paper template and used some of the extra covering included to seal the edge around the canopy. See photos below for details.
Mounting the Cowl:
Tower included several hardwood mounting blocks for the cowl. Align the cowl to provide enough clearance for the spinner back plate if using one. I also like to visually align the cowl to make sure it is centered left and right and up and down while looking down the propeller shaft. Once satisfied with the alignment, secure the cowl in place with blue painters tape and begin to drill holes for the mounting screws one by one.
That’s pretty much it! This was one of the quickest ARF builds I’ve done and was easily accomplished in a few evenings!
Just a few additional notes:
Plan on using a fairly large battery for this Ultimate Bipe as you will need the extra nose weight in order to achieve correct CG. I’m getting seven minutes of flight time on a 4500 mah 6S pack with a lot of sport flying and several full throttle bursts!
I setup my control throws using the low rates in the manual for the maiden flight. However, even the low rates on ailerons felt way to responsive. I found my self cutting those back to around 1/4 to 3/8 of an inch of throw up and down. I dialed in around 30% expo for the maiden flight as well.
One issues to note with the landing gear is that the landing gear studs do not appear to be long enough to allow the nylon lock nut to fully tighten. I used blue thread lock to remedy that situation.
The Rimfire 55 motor provides plenty of thrust and vertical power using a Xoar 16×6 prop. In the manual they recommend a 16×8 for ultimate (pun intended) performance. I’ve pushed the plane pretty hard with the 16×6 prop and the motor hardly reaches above room temperature. The Tower Hobbies Ultimate Bipe had plenty of air flow and is also aided by the spinner I’m using from Gator RC. NOTE: the motor mounting template appears to show the motor mounted off center – this is normal as it accounts for the amount of right thrust built into the firewall.
Finally, I decided to use the Castle Creations 10 amp BEC since I was powering six digital servos.
The main purpose of this article was to focus more on the build aspects of the plane but I do want to share a few notes about it’s flight characteristics. The Tower Hobbies Ultimate Bipe will easily lift off the run way at a little above half throttle. This particular plane can be flown nice and easy or full on 3D if you wish! It will handle anything you can throw at it. It seems to roll as if it’s on a string – staying precisely in it’s track and responding only to your inputs.
When setting up the CG location at home before your first flight be sure to not make it excessively nose heavy as you will end up having to dial in so much up elevator. The Tower Hobbies Ultimate Bipe tends to like it CG location to be where the fuselage is level with the ground. With the CG correct it should take very little elevator to maintain level inverted flight.
Landing the Ultimate Bipe is also a pleasure. You are able to ease it in with a little throttle and gently set it down with a slight nose up attitude to bleed of some of the air speed on final approach.
Knife edge flight did not produce any coupling or any unwanted characteristics.
Overall the Ultimate Bipe is a clear winner from Tower Hobbies!
- Rimefire .55 Brushless Motor
- Tactic TS25 Digital Mini Servos (6 or 7 needed with glow)
- Futaba R2008SB 8 Channel RX
- Pulse 4500mah 6S 45C LiPo
- Castle Creations 75 amp Edge ESC
- Castle Creations 10 amp BEC
- Xoar 16×6 Beachwood Prop (the Xoar prop was a direct fit with the included prop adapter with the Rimefire .55 motor – no prop reaming required)
- Gator RC Electric Spinner – size based on preference.
- Deans plugs for battery connections.
Some Additional Photos