The Legacy Aviation Muscle Bipe is loosely based on the hot rodded and highly modified Waco UPF-7 flown by the late airshow legend Jimmy Franklin and known as the Mystery Ship. The Muscle Bipe is Extreme Flights tribute to Jimmy and to classic barnstormer airshow style aerobatics. Many of you know how big of a Extreme Flight Fanboy that I am. I haven’t had a single version of one of Chris Hinson’s planes that hasn’t been an amazing flyer. I obtained my first one (A 60″ Lazer) from Mark Trent several years back and flew the covering off it until I roasted it into the runway on takeoff. That airplane is currently being flown by Bob Schmidt. There is no telling how many flights that plane has on it. Has to be in the 500+ range. Don’t tell Mrs. Grant but I can neither confirm nor deny that there either ARE or HAVE been the following in the Hanger. You look at this list and I think I need to get a darn discount from Extreme Flight:
- 95″ Extra 330 SC-E (Orange Blue and White).
- 80″ Bushmaster (Blue and White)
- 74″ Lazer (Red, White, Blue)
- 60″ FW-190 (Red Tulip)
- 60″ MXS (Baby Metal)
- 60″ Extra 300 (Yellow, Blue and Orange)
- 52″ Pantera (Blue and Yellow)
- 52″ Pantera (Red, White, Blue) – Deceased
- 60″ Slick 580 (Red, White Blue) – Deceased
- 60″ 3DHS Edge 540 (Demonstrator) – Deceased
- 36″ Speed Freak Outlaw (Blue, White, Silver) – Deceased
- 60″ Laser (Yellow and Blue) – Donated to Bob!
- NOW THE 54″ Muscle Bipe (White w/Black Scallops)
Finally, a Biplane!
I have been waiting for Chris to come out with a Biplane for months and possibly years. I love biplanes and none of them came close to meeting my performance expectations or looks for an awesome Bipe. The closest I came was with the E-Flight Prometheus designed after Skip Tuckers aerobat but it had a pitiful spinner, flexy landing gear, and wasn’t very durable with high speed snaps and knife edge spins. I almost tore the tail off that thing and its currently held together with Blenderm tape until I get the energy to repair it. My checklist for an awesome biplane was:
- Balsa and Monocote/Oracover
- 50+ Inches
- Golden Age Style (Waco Like)
- 6S Electric Power
The kit comes from Georgia in an awesome overpack brown box over the white retail box. The packaging is legit. I’ve never had a plane damaged in shipment from Extreme Flight, even the 95″ and its 3 giant boxes were undamaged. I heard that Bob Allen had his 65″ Baby Bushmaster damaged but Chris hooked him up with a replacement fuse. The plane always comes with all the parts individually wrapped and taped together for rigidity and to prevent things from flying around. The Fuse and Wings are separate and there is usually a box for the cowl on one end and another with loose parts on the other. If you purchase accessories (Motor, ESC, Servos, Servo Extensions Horns, Propeller, etc) those things are securely placed in the box. They always give you wing bags (Silver Mylar Bubble Wrap Style) for all the extreme flight planes for transport and include a spinner nut in the kit.
Wingspan: 54 inches
Length: 48.6 inches
Wing Area: 803 sq.in.
Weight: 6.5 – 7 lbs.
One of the things I love most about Balsa and Covered airplanes is that you have a lot of options to use components that are of a little better quality than you get with a foamy. You can spend as much or as little as you want.
I always recommend going with the Extreme Flight Torque motor. The 4016T/500 Mk II is legit. Couple it with a Castle Talon 90, probably one of the best ESC’s on the market, and a 70C battery and your ready to tear the sky wide open. Mine pulled about 74 Amps during a flight with both propellers. I liked the look of the Falcon Civilian propeller with its old school wooden look with brass fasteners so I went with it initially and tried the Xoar on subsequent flights.
- Motor: Torque 4016T/500 MKII
- ESC: Castle Creations Talon 90
- Battery: Pulse 6S 3700 mAh or Admiral 6S 5000 mAh
- Prop: 16 x 7 Xoar Beechwood Prop And a Falcon 16 x 8 Civilian
- Aileron Servos: (4) MKS HV69
- Elevator/Rudder Servos: (2) MKS-HV9767 High Voltage Servos They recommended the Hitec HS-7425’s but I chose to go with the MKS servo so I can standardize on the 25T spline arms. I buy them by the dozen and use them on most of my models.
- Servo Arms: (6) Extreme Flight Servo Arms – 1.25″
- Servo Extensions: (4) 6″ and (4) 18″ 28ga Extreme Flight Twisted
- Receiver: Futaba 7008SB controlled by the Futaba 18SZ
- Current Telemetry: Futaba SBS-01C Current Sensor
- Flight Controller / Gyro: Bavarian Demon Cortex Pro
When you have built 13 Extreme Flight aerobats, you get to the point that you just dive right in and start assembling and use the manual as a coaster for your Rum and Diet Lime Coke. The cool thing about Extreme Flight is to watch them constantly improving materials and quality as well as simplicity of build. You can tell they see things that would be “Even Better If” and incorporate them in subsequent versions of their models. The kit arrived and didn’t need 2 seconds of a covering Iron. Everything was tight and wrinkle free.
The first step is to CA the pre-hinged surfaces. I put a pin in the center of each hinge to insure that they are centered and then deflect the hing completely both ways. Once the “Gap” is set, I thin CA the hinges and work them back and forth, finishing with a “Tug” when they are dry.
The carbon fiber gear goes on with 3 screws and the wheelpants are held on with the axle. On previous planes the pants would twist around and every once in a while you would have one hanging. The last 2 or 3 planes I have built have a gear notch molded into the pants so they will not rotate. Awesome fix.
The top wing of the plane has a center section and the outer panels plug in. This prevents you from having to mess with screws and cabane assembly at the field which is a great design. Problem is, you need tiny little child hands to get down in the fuse and get the fasteners in and tight. As usual, the first one takes 15 minutes and the subsequent 3 take 2 minutes.
Wings were a typical setup with the servos located under a small slotted panel with the arm penetrating up to the linkage. I LOVE how Extreme Flight handles their Surface Horns. The horns are fiberglass and get epoxied into a slot. Gone are the days of screwing around “Pun Intended” trying to get 3 little fasteners through a tapered surface and actually fit into the backing. These drop in and fit perfectly. I sand the surface that gets the glue and then use a big fat XL sharpy and “Paint” them black. The hardware is legit with ZERO slop. The MKS-HV69 is a new High Voltage Micro servo from MKS. It is a metal Gear servo that puts out a Whopping 141.7 oz/in (10.2 kg/cm) @ 8.2Volts in .10 seconds. They are small, fast, and crazy strong as well as not too expensive at $59 each. I run all my setups at High Voltage now to reduce the current load on the receiver. Just hook to the Talon 90 and set its BEC to higher voltages. Make sure all components can handle the voltage.
The only issue I had with the servo install was routing the cables through the wing. The airfoil is pretty thin and there isn’t a lot of room to pull the wires through. It took some fishing but after a while it happened. The top wings plug into center section and screw in. The extensions route down the cabanes. If I had a little foresight I would have put some black shrink tubing around the cabanes before I installed them to cleanly secure the servo wires. I was too lazy to take the fasteners out so mine are just twisted around the metal cabanes and into the model. The bottom wings plug right in old school style and are held in place with a single screw on each wing. Both wings have a strong carbon fiber spar/wing tube. With both wings installed you gently separate the wings and slide the struts into the slots in the outer wing panels. They seat pretty easily (pay attention to the markings for left and right, top and bottom) and push them flush. They have supplied pins that push into the leading edge of the wing and go through the top and bottom of the strut to hold them in. A pretty ingenious design. I’m not going to disassemble mine to transport to the field but if I were, this is a not tool free (Pliers / 4 Allen Bolts) assembly that is doable in 5 min or less.
The elevator epoxies into the slot without fanfare. Peel the covering off to get a good bond. Nothing special. The servos are installed under the elevator in the sides of the fuse. I did notice that at full rudder and down elevator deflection the elevator hits the linkage. Once the radio throws were set later it wasn’t a problem.
The Torque motor just screws to the firewall and the length is correct for the cowling. You have to replace the bullet connectors for the Talon 90 ESC and I solder the Current Telemetry sensor in the positive lead from the battery. Everything mounted fine in the cowling with no excitement.
Receiver / Gyro:
The beautiful thing about the R7008SB is that it has both SBus and SBus2 and it works flawlessly with the Bavarian Demon Cortex. First, setup your receiver without the Demon and setup all your throws. Once that is done, you just plug a male to male servo cable between the SBUS port and the BUS port on the Demon (plug B). Plug all the control surfaces into the Demon in their respective channels 1,2,3,4, etc and fire it up (without a prop of course). Once its powered up, insert a bind plug into the program port. The Demon will detect the SBUS and when it slowly flashes blue you pull the bind plug out. Power down the system, plug the bind plug in and power it back up. The Demon is now it (Teach/Learn Mode). The surfaces will twitch and you hold full left aleron, surfaces twitch, hold right aileron, surfaces twitch, hold up elevator, surfaces twitch hold down elevator, twitch, hold right rudder, twitch, hold left rudder, twitch, flip the switch you will use to set the mode. Done. Demon is programmed. You go into your radio and set the endpoints of the switch you have programmed for the mode to set the amount of gain. I usually use endpoints of about -21 / +21 for a starting point. I can program a slider on the Futaba to change that value so I can adjust gain in the air. Make sure the Demon is mounted with the plugs toward the front of the model and put it into normal mode. Pick up the plane and rotate it axially. The aileron should correct your movement. If you cannot see it, increase the gain until you do. If you rotate it for to the right it should compensate for left aileron. Yaw it left and it should add right. Pitch it down and it should give up elevator. I’ve never had it not be correct on the demon. Plug the data cable from the telemetry sensor into the SBus2 port on the receiver to collect information from the ESC on total volts, max current, current current (see what I did there), and total current consumption. I program my temporary switch so that Futaba Siri tells me how much current I have consumed. This allows me to eek out as much flight time as possible without a need for a timer.
The Radial Dummy Motor:
The dummy engine that came in the Bipe was a flimsy piece of black plastic. I immediately tossed it and designed and printed my own version of a dummy radial. I plan on doing a separate article on making dummy radials soon so stay tuned.
The Muscle bipe was a fair investment but considering your getting 2 times the wings and a much more complex round structure in the fuse its not crazy. Total investment here was about $1500 in the air minus the battery but you could easily get her going for less than $1000 with some more frugal electronics options. The breakdown is as follows:
- Muscle Bipe Kit – $360
- Torque Motor and ESC – $170
- Servos – $415
- Propellers – $25
- Servo Arms, Extension’s, Miscellaneous Hardward – $70
- Current Telemetry and R7008SB Receiver – $200
- Bavarian Demon Cortex Pro – $300
- 3D printed Dummy Radial Engine – $3 in filament!
Flying the Muscle Bipe:
It seems that every time I want to maiden something there is 15mph and 90 degree crosswinds. Today would be no exception. The real test to a daily flyer. I tossed in a Pulse 6S 3700, closed the cowling / hatch, straddled the tail and ran the power up to full throttle and checked the Current on the Futaba. It read 68A so I was ready to roll. Taxied her out on the runway, took a few pictures, and then pushed the throttle forward. I was surprised at how well it tracked with the strong crosswind. I almost didn’t have to add any rudder since the wind was helping push the plane right for me.
A power tip for tail-dragger flyers is if you have a 90 degree crosswind right in your face, takeoff left. If you have a 90 degree crosswind from behind you, take off right and let the wind help keep the model straight!Ralph Grant
The Muscle Bipe was in the air at about 2/3 power and it climbed gradually out. 2-3 clicks of down trim and she was perfect. I immediately felt comfortable with her and put her through the paces. Loops, rolls, stall turns, knife edge, snaps, spins, everything. She did it all. Stalls were flat and predictable. After about 5 minutes I had consumed about 3100mAh so I set her up for landing. The Muscle Bipe doesn’t slow down as quickly as other biplanes which was surprising to me, especially considering the sizable cowl. I think it must be due to the relatively thin airfoils on the wings. She came down the runway straight as a string even with the crosswind thanks to the Demon and settled in nicely. I taxied her back and put her up 2 more times. On the 3rd flight I changed to the Xoar prop and was surprised to get less flight time. About 4 min. I would have thought that the big civilian prop would have been less efficient but that was not the case. The Muscle Bipe is already one of my favorites! Next time I fly I’m going to put her up with a 5000mAh battery and see how she does! I bet I can get 7min out of her.
The Extreme Flight Muscle Bipe is a fantastic sport and aerobatic flyer. I wouldn’t call it a 3D plane but that is not my flying style anyway. The Bavarian Demon Cortex Gyro and Current Telemetry isn’t needed to enjoy the plane but it certainly makes a daily flyer more fun, especially in crazy cross winds. I would easily fly this plane in up to 20mph winds. It will do all your favorite maneuvers and I cannot wait to get her up on a calm day and see how great she fly’s. Inverted passes down the runway are in my future. Only thing I would change is to get a scarf on my open cockpit pilot so I can see it flap in the wind when he flies by. Take care, see you at the field.