Legacy Aviation Muscle Bipe - Assembly/Fly/Chat Thread

Here is a great build thread and all the info you need on the EF Muscle Bipe from my good friend and RCGroups member Jeff Williams!


Legacy Aviation Muscle Bipe

The Legacy Aviation Muscle Bipe (MB) is arriving and now is the time to start a full thread and go over the assembly and flying of the MB. The plane was announced at the Toledo 2019 show, was first flown at Joe Nall 2019 and since has had little coverage till now. I was the lucky guy to have the only flying version for many months, write the assembly manual and play with it for months till now. So now is your time to get one and enjoy a biplane with aerobatic capabilities, smooth slow flight and no bad habits. The plane is constructed of ply, balsa, carbon and covered with oracover has fiberglass cowling and wheel pants that are painted, the hardware is included. You will need some things and I will have that list in a subsequent post, mine has standard equipment that is available to any of you.

  • Motor - Torque 4016-500 MKII
  • ESC - Castle Creations Talon 90
  • Servos - wing MKS HV69, rudder/elev Hitec 7245MG
  • Prop - Xoar 16X7
  • Aura 8 AFCS
  • (4) 6" Extreme Flight 28AWG servo extensions
  • (4) 18" Extreme Flight 28AWG servo extensions

Flying the MB I use a 6S 3300-4000mah lipo. Generally, I get about 6-7 minutes with a 3700mah lipo. Using the Talon 90 you will not need a separate battery to power your receiver. I used an 8CH receiver, but a 7CH would work. OK let's begin the assembly.

Initial flight Joe Nall 2019 (5 min 3 sec)


Last edited by Jim T. Graham; Jan 28, 2020 at 08:46 AM..
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Jan 22, 2020, 09:22 PM
Team EFRC, Castle, BandE
Thread OP
Since I wrote the assembly manual I will try not to simply repost it here. Follow the manual, I hope I made it easy to follow with enough detail for any skill level. Here I will supplement the manual and provide additional photos, as with any manual, we are limited on how many photos we can include or we have a dictionary thick manual. I also want to direct you the new Extreme Flight RC youtube channel, to access this go to: https://www.youtube.com/channel/UCC_..._as=subscriber
you will find MB assembly videos as well as other how to and flying videos of everything Extreme Flight. Visit the channel often as content will change regularly.
OK, so when your MB arrives, examine the box and make sure no shipping damage has been incurred, if it has follow the shippers protocol for such an incident and let EFRC know so they can follow their policy for such an incident. If all is good then lets open the box and check that all the parts are there. The box should have a fuselage, 4 wing panels and a single center wing panel, rudder, horizontal/elevator, tailwheel, 2 tires, main carbon gear, 2 piece cowling, 4 center wing brackets, 2 cabanes/struts, 4 strut holding pins, hardware package, spinner nut, 2 wheel pants, pilot figure, windshield, graphics sheet. I cannot detail the hardware package but expect to see pushrods, ball links, bolts, axles, collars, nuts and washers as a general guide. If all this is good proceed, if not contact EFRC.
This model was built in China, loaded onto a ship and floated to the USA, thus you can understand many atmospheric changes have been upon this model and the covering will need to be gone over. What we mean by that is take a covering iron and heat gun and spend some time going over the entire model piece by piece paying extra attention to the seams, stripes and any bubbles/wrinkles in the covering. A video detailing how to do this will be on the EFRC youtube channel soon. Once to your satisfaction, now take thin CA and go over the internal wood joints to the best that you can reach them. I especially make certain to apply thin CA to the stress points, typically these are gear mount block, firewall, wing attach, eppenage and cross bracing, avoind spraying accelerator on thin CA this introduces air into the glue and severely weakens it. Allow the thin CA to flow into the joints, but be careful not to apply too much as it is like water and will flow everywhere if not careful.
Jan 23, 2020, 01:12 PM
Team EFRC, Castle, BandE
Thread OP
Wing Assembly:
Locate your 4 wing panels, the center section will be used later. First lets install the ailerons to the wing using the included CA hinges. The Extreme Flight RC (EFRC) youtube channel has an extensive video on how to do CA hinges, if not familiar plz view that. Attach the ailerons to all 4 wing panels with CA hinges and allow to dry, I used thin CA from Zap with a tip. Be sure the hinges stay centered and that you have the ailerons oriented correctly for the wing panel to which they belong. Next we will install the control horns. There are 4 control horns that are the same, the manual has a picture distinguishing the wing from the tail control horns. Scuff the lower section of the control horn and one side of the base plate, this will help attain better adhesion. Dry fit the control horn and base plate into the slot and be sure it is flush with the wing's surface, remove the covering under the base plate for better adhesion. Be sure to not cut into the balsa when doing this, when satisfied mix up some 30 minute epoxy or your favorite glue for this and install the control horns/base plates. Next gather your wing servo (MKS HV69), pushrod, ball link, bolts/washers/nuts and servo arm. Route the servo wire thru the lightening holes and out the wing root, the lower wing panels will need a 6" extension (EFRC 6" 28AWG extension), there should be strings running thru the wings to aid in pulling this servo wire thru the wing. Orient the servo shaft forward, electrically center the servo, install the servo arm so it is parallel to the hinge line. Should you not be able to get an alignment, then go to your radio and move the servo till parallel to the hinge line. It should require very little adjustment from your transmitter, now thread the ball links onto the pushrod and begin threading them till they center on the servo arm and the control horn. Be sure the aileron is centered when doing this, once you have this put a washer on the supplied 2mm X 10mm bolt and then thru the ball link and onto the servo arm and the proper side of the control horn, do this entire step on all 4 panels.
Jan 23, 2020, 07:35 PM
Team EFRC, Castle, BandE
Thread OP
Gear Assembly
One of my favorite part, lets get it on her legs. Begin by locating all the gear parts, I have a photo below identifying them. First lets install the main gear, we must confirm the orientation of the main gear. This particular gear is installed with the sweep going forward, you can determine the sweep by putting the gear on a flat surface with the ends in the air and the mounting portion on the surface. View the gear from the side and you will see a slight sweep, if you cannot see it then use a square. Once the orientation has been determined I chose to mount the main gear using the 4mm bolts and washers that will go into pre-installed blind nuts, be sure to use blue thread lock (BTL) on the bolts. Next I chose to install the cuffs, you do not have to use them but it sure gives a more pleasing/finished look in my opinion. The cuffs are a little longer on one side and this will be oriented to the outer side of the gear, dry fit the cuffs and once you are happy with the fit/look glue them. I used Foam Tac but Welders adhesive or other similar craft adhesives will work, I don't advise CA. Even thick CA will likely be too runny and brittle for this application. I like the Foam Tac, or similar adhesive, because when dry they are still somewhat flexible and considering the gear will flex some with landings a flexible glue works best. I used painters tape to keep the cuffs in place while they dried. Next I took the axles, washers and nylon insert nuts and slid the threaded end of the axle thru the gear and the smooth portion with hex head on the outer side of the gear, slide the tire onto the axle, then put the pant over the tire and get the slot in the pant next to the gear, the hex head will actually be inside the pant. This is the dry fit where we will determine where the tire will be positioned so it does not rub the pant, find this point and make a mark where the tire will be. Take the pant off, install the wheel collar, be sure to use BTL on that set screw and you can position it all back together and tighten the nylon insert nut.
TIP: I file a small flat spot where the set screw in the wheel collar will contact the axle, it holds better on a flat spot instead of the round axle but do not file much, the flat spot should be barely visible. Repeat for the remaining pant/axle/tire.
Jan 23, 2020, 07:55 PM
Team EFRC, Castle, BandE
Thread OP
Tailwheel Assembly
Locate your tailwheel package, this should have all the parts enclosed. I started by centering the tailwheel onto the axle, make a mark then file a very small flat spot so the wheel collars will be secured to that flat spot. This will allow a better hold of the wheel collar.
TIP: make those flat spots on the bottom of the axle this will allow easier access to the set screw should any adjustments be necessary.
Once you are happy with the tire location on the axle, I go ahead and secure it with the wheel collars. Now I position the mounting portion of the carbon fiber bracket on the bottom rear of the fuselage such that the swivel point of the tailwheel directly under the rudder hinge line. Once you get this then position the mounting porting so it is centered on the bottom of the fuselage while maintaining the swivel point under the rudder hinge line. Once you get this now secure it with tape and make marks in the 3 holes, then drill these holes with a small bit. Be sure you use a drill bit that will keep a tight fit with the wood screws. When done drilling, mount the tailwheel to the fuselage.
TIP: when inserting these wood screws into the fuselage I apply a very small drop of thin CA onto the screw, this acts similar to thread lock but you can still get the screw out.
The last thing to do is put the small tiller mounting screw into the bottom of the rudder so you be able to steer the model. However, we cannot do this now as do not have the rudder installed, be sure to keep this small screw in a place for later use.
Jan 23, 2020, 08:29 PM
Team EFRC, Castle, BandE
Thread OP
Center Wing Assembly
Locate the center wing section, 4 mounting bars and bolts. There are slots already cut into the fuselage for the mounting bars, start with any hole and slide the bar into the slot and line it up with the holes inside the fuselage, install the 3mm bolts and use BTL. The angle on the mounting bar will point to the wingtips for proper orientation. Repeat for the remaining 3 mounting bars. Now position the center wing section onto the mounting bars and you will notice there are slots in the center wing section to receive the mounting bars. You may need to slightly bend one or two of the bars to get them into those slots but it will likely be a minimal push or bend to achieve a proper fit. Once this is all positioned then install the 3mm with BTL into the bars/wing and tighten.
Jan 23, 2020, 09:07 PM
Team EFRC, Castle, BandE
Thread OP
Horizontal/Elevator/Rudder Assembly
Locate your horizontal stabilizer and elevator. Be sure you know the top from the bottom, the scheme will match the wings for top/bottom. Now remove the filler block (it is not glued) from the middle section of the rudder hinge line, this will allow access to the horizontal stabilizer slot. I strongly suggest dry fitting the horizontal and checking alignment with the wings on, but some just install the wing tube and then measure for alignment. You will want to pay close attention, take your time and achieve a proper alignment of the horizontal stabilizer. Just because there is a slot for the horizontal stabilizer it does not guarantee perfect alignment, you may have to weight or tape one side of the horizontal stabilizer to keep it parallel to the wings/tube. I set my Muscle Bipe (MB) on top a small step ladder then viewed it from the front and back to be sure it was parallel. I also measured from a point on the horizontal to a fixed point on each lower wing for side to side alignment. Once this is aligned, I used 30 minute epoxy to glue the horizontal stabilizer in place. Now hinge the elevator to the horizontal stabilizer using the same technique as we did on the ailerons for hinge installation. Next reinstall the filler block and glue in place with CA or epoxy. Now we will hinge the rudder, but we want to make sure the rudder sits on top the tailwheel tiller arm as we will be installing that small screw soon and need to be able to get it into the bottom of the rudder, however the rudder should not be pushing on the tiller just barely touching. Be sure the rudder counterbalance is free and not rubber on top the vertical stabilizer, once this is all satisfactory then CA those rudder hinges. I installed the elevator and rudder control horns at this time using the same techniques as we did with the ailerons.
Last edited by jwilliamsrc; Jan 23, 2020 at 09:27 PM.
Jan 23, 2020, 09:26 PM
Team EFRC, Castle, BandE
Thread OP
Elevator and Rudder servo installation
The elevator and rudder servo installations are exactly as we did with the aileron servos. However, just a few things will need to be looked at before we get started. First, connect a 18" servo wire extension to each servo and then route the wires up thru the fuselage until the ends that go into the receiver are in the lower wing bay area.
TIP: route the servo extensions thru lightening holes to protect the wires from fraying while doing aerobatics. I even affix the wires to those areas with one wrap velcro so there is no flopping of the extension, this further reduces any damage to the protective coating on the extension.
Now that you are ready to install each servo, take a look at the picture below which identifies the exact pushrod to the correct servo and control surface. Each servo is oriented forward, also center the servo with your transmitter and gain the best mechanical geometry before going into your transmitter and doing adjustments.
Jan 23, 2020, 10:00 PM
Team EFRC, Castle, BandE
Thread OP
Motor and ESC installation
Lets move to the front of the MB and begin the installs on the motor and esc. I chose the the Torque 4016-500 V2 motor and Castle Creations Talon 90 ESC for my power combination. One huge advantage is the MB was designed around this power combo so the installation is mostly done. What I mean is this, the Torque motor will simply bolt to the existing holes/blind nuts in the firewall thus making this a nearly plug and play install. A few things I did do and you may consider are these, orient the motor such that the wires are at the bottom of the motor box. I chose to mount the ESC to the starboard side of the motor box and I secured it with one wrap velcro. You may need a servo extension to reach your receiver, we don't put this in the items required to finish because different brands ESC's have different length wires from the ESC. Also many of you will elect to mount your receiver in a place the ESC receiver wire will reach so you will have to decide on this extension. I used a 6" extension to reach my RX. When bolting the motor to the firewall be sure to use BTL on the 4mm bolts. If using the recommended power system you will need to solder the Castle Creations provided bullets onto the Torque motor to fit the ESC. The stock bullet connectors on the Torque motor are too small for the CC Talon 90 is why you will need to resolder these connectors.
Jan 23, 2020, 10:27 PM
Team EFRC, Castle, BandE
Thread OP
Cowling and radial engine insert installation
This is usually a step where most of sort of cringe because of the alignment between the cowling, motor and spinner are delicate. Well this MB has done away with that worry, this cowling could not be more simple. The design is a two piece cowling with a radial engine insert to simulate the full scale plane. The way these are secured is straightforward, so lets look at the cowling first. Locate the lower portion and you will notice it has a cowl ring that fits up to the front of the MB which has two protruding hooks that grab the lower portion of the cowling and then upper section of the lower cowling has two 3mm bolts to fully secure it to the MB all remaining inside the cowling for a clean finished look. The upper section of the cowling simply has two hooks on the front portion that lock into the lower cowling then slides back with alignment pins and then magnets touch to keep it in place. It is a good idea to fit this together before proceeding with the radial engine insert. Once you are satisfied of how the cowling fits, then we can move to gluing it in place. I started by laying the lower section of the cowling on my work table front side down. This will allow me to fit the radial engine insert into the cowling and gauge how it fits. There are two recesses in the insert that align with top section of the lower cowling. It may require some trimming, in my case it fit perfectly and I was able to scuff the areas inside the cowl that will receive glue. I advise having something handy to apply pressure on the radial engine insert to hold it perfect position while the glue dries. Take your time and do plenty of dry fitting until you are happy with the fit and look of this section then apply your glue. You will have to cut the center of the insert out to allow the Torque motor thru and fit the entire assembly onto the aircraft.
Jan 23, 2020, 10:45 PM
Team EFRC, Castle, BandE
Thread OP
Strut installation
Locate the two struts and 4 strut securing pins. Mount the wings onto the plane and I will explain how to install these. The struts can only fit one way due to the wing stagger. Below are pictures if you are unable to decipher which strut goes to which wing. Once you have this, there is a method to inserting these and I recommend inserting the strut into the lower slots and have the strut angled toward the wingtip. To get the strut into the upper wing you have to carefully spread the wings then rotate the strut upwards into the upper wing slots. Once you have this then locate the hole on the leading edge and the securing pins will go into the upper and lower wings. To install these, the pointed end goes in first and I admit it is a tight fit and you may have to jiggle the strut and/or wing to get the pin into the strut, caution that you DO NOT push the securing pin flush with the wing's leading edge. Leave about 1/4" of the pin protruding so that you can use a pliers to grab the pin and pull it out for disassembly. Also DO NOT force the pin, as I said it may be tight but if aligned it goes in, if your pin stops and is taking significant pushing to insert the pin then it is not aligned. Be careful to get these installed correctly.
Jan 23, 2020, 10:51 PM
Team EFRC, Castle, BandE
Thread OP
Upper wing servo wire extension installation
You will need to route (2) 18" servo wire extensions from the RX up thru the fuselage, along the center wing mounting bars, then up thru the center wing so you will be able to connect the upper wing aileron servos. To dress this up I used black electrical tape to encapsulate the extension as it runs along the mounting bar. You could use black heat shrink tubing also.
Jan 27, 2020, 12:05 PM
Team EFRC, Castle, BandE
Thread OP
Windshield and Pilot install
Legacy provides a pilot and windshield that can be installed and I felt really added a nice touch to the plane's looks. I started with installing the windshield, you will need to trim it to fit, take a little time to trim this exact and you will really like the final look. I glued the windshield with foam tac, but similar adhesives would work too. Next the pilot gets glued in place. I began by just simply placing the figure in the area and then getting back 5-10 feet and judging the overall appearance. I ended up with the pilot aft of center in the cockpit area, but you can move it around some to suit your preference. I taped the windshield in place while the adhesive dried.
Jan 27, 2020, 12:13 PM
Team EFRC, Castle, BandE
Thread OP
Final Assembly and Setup
At this point the basic assembly is done, we now need to locate some items within the fuselage. The receiver, gyro if desired and switch if desired will need locations. I opted to put my receiver on the tray just inside the removable baffled access panel on the underside of the fuselage. I secure it with Velcro one wrap and I located my Aura gyro on the very aft section of the battery tray and also secured that with Velcro one wrap. Any satellite receivers could be taped to the fuselage sides. Next I installed the 16X7 propeller (not included) and then the included prop nut, I advise you finger tighten first then about another half turn. Do not overtighten as the Torque motor shaft is aluminum and the threads will strip if overtightened. Once you have all these items positioned and propeller secured, wings and battery installed lets find the center of gravity. I did this with the old fingertip under the upper wing method, if you have a CG machine or other device all the better, but I found this old tried and true method to work fine on this plane. I placed my fingers under the upper wing near the wing bolt hole and got an initial CG location. I was fortunate that where I located everything was the preferred CG location. EFRC recommends a 6S 3300-4000mah lipo battery which can be slid forwards/backwards in the tray to move the CG. I have some pictures below to help identify my setup.
Last edited by jwilliamsrc; Jan 27, 2020 at 12:39 PM.
Jan 27, 2020, 12:35 PM
Team EFRC, Castle, BandE
Thread OP
Gyro, Control Throws and initial flights
The MB certainly does not need a gyro, but I opted to try my first gyro ever, in 40 plus years of RC flying I had not tried a gyro but this time I went with the Aura 8 from Flex Innovations. I admit I got a lot of setup help (lets face it I was spoonfed) from Seth Arnold at Flex, but it yielded a really nice balance between smooth flight and not being too controlling. I suggest spending some time on the Flex Innovations website, or a phone call, to get this right. I have a cable between my Spektrum 8CH receiver and the Aura, then all my servos are connected to the Aura. There are so many ways to setup this gyro and so many of you will have different preferences from mine, plus it would be tough to screen shot all the gyro settings that I don't feel it is worth posting. However, we are working on a way that my settings will be available at some point. I will say, I have mine set that after about 25% stick movement the gyro no longer has any input, I basically have mine set to keep it stable during constant flight paths.
My control throws are based on having triple rates. I use one switch on the upper right of my TX to switch between low/middle/high rates. Now that I have flown the model several times I found middle rates are my preference and I rarely switch out of it. I have let many different people fly the MB, those who fly 3D said the middle or high rates are fine, but those who don't may opt for the low rate. Below are merely starting throw rates, but it is exactly what I have on mine.
Recommended throws:
Ailerons Elevator Rudder
Low: 5/8” or 15 degrees/20% expo… 3/4” or 15 degrees/20% expo... 2” left & right/25% expo
Med.: 1 1/4” or 25 degrees/30% expo… 1 1/4” or 23 degrees/30% expo… 2.5” Lt/Rt./35% expo
High: 1 3/4” or 37 degrees/40% expo… 1 3/4” or 30 degrees/40% expo... 3” Lt/Rt, 40-45% expo

With the CG set to exactly as I posted above and using a Pulse 6S 3700mah 60C lipo, I found the MB to be a very relaxing plane to fly. It is responsive in all 3 axis, has plenty of power from the recommended Torque motor and have yet to find any bad habits. Keep in mind this is NOT a 3D plane, it is a sport plane capable of many aerobatics, loops, rolls, spins, inverted flight and knife edge are all maneuvers the MB will perform with grace and ease. Takeoffs require very little rudder to keep it straight and landings are predictable. I did find that landing with just a little power is best, trying to float it in without any power resulted in hard landings, while keeping a nice stable descent path with power to touchdown resulted in very consistent landings. I really like how axial the MB rolls, whether performing full rolls or point rolls, the MB will track nicely and stops the roll when you do, it can roll very fast if desired. Overall the MB is really fun to fly and it looks spectacular in the air. I hope this thread helps make your experience easier and more fun, don't hesitate to PM me with any questions.

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