I will use the next series of posts to document the process I use. If you have any comments or additional details feel free to add to this chain.
I start with mounting the wing. The MFL has some counter sunk recesses molded into the wing. The front bolts are designed for 1/4-20 and the rear for 10-24s.
Fit the spar joiner tube by cutting it to the proper length and join the wing halves by sliding them together and taping them in place.
I have designed some small tools to aid with drilling holes consistently (at least that is the attempt). I use these guides to drill the pilot holes in the wing. I use a 3/16" drill bit for 1/4-20 threads and a #25 Drill bit for 10-24 threads. Drill the pilot holes in the wing.
Place the wing into the saddle and mark the bolt locations on the fuselage. The center line of the wing should line up with the center seam line of the fuselage and if lined up it will be perfectly straight.
Next install ply backing plates to accept the threads inside the fuselage. Normally, I use 1/8"-1/4" aircraft ply cut into 1/2"-5/8" square pcs and these are 5 min epoxied onto the existing ply plates installed when received. The hole marked locations can be used to make sure your blocks are centered over the best location for the threads.
MFL (CMAD) Build instructions
MFL (CMAD) Build instructions
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- 3D printed guides for drilling, reach out if interested. The reverse counter sink centers the guide in the wing and the outer surface allows the drill to sit perpendicular to the surface.
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- Drill pilot holes using a 3/16" bit and the drill guide
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- Drill pilot holes using a #25 bit and the drill guide
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- 5 min blocks in place to add additional thread support
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- 5 min blocks in place to add additional thread support
Re: MFL (CMAD) Build instructions
MFL cont:
Next tape the wing in place. Line up the center line of the wing with the center seam of the fuselage and tape the wing down as shown. Once you are happy with the alignment, flip the model over and add additional tape along the fillets securing the wing to the fuselage. The reason for this is to keep the wing aligned during the drilling and tapping process. I start with one of the front bolts. Using my guide and the 3/16" bit, I drill through the wing into the fuselage and the ply plates. Next I tap that drilled hole and install a 1/4-20 bolt. I only do one front bolt at this time and switch to the rear bolt opposite to the first drilled and tapped hole. Follow the same process with the #25 bit and the 10-24 bolt for the rear before finishing the other two remaining bolts.
Next tape the wing in place. Line up the center line of the wing with the center seam of the fuselage and tape the wing down as shown. Once you are happy with the alignment, flip the model over and add additional tape along the fillets securing the wing to the fuselage. The reason for this is to keep the wing aligned during the drilling and tapping process. I start with one of the front bolts. Using my guide and the 3/16" bit, I drill through the wing into the fuselage and the ply plates. Next I tap that drilled hole and install a 1/4-20 bolt. I only do one front bolt at this time and switch to the rear bolt opposite to the first drilled and tapped hole. Follow the same process with the #25 bit and the 10-24 bolt for the rear before finishing the other two remaining bolts.
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- I have known others to glue your wing down... of course some wax or mold release is required.
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- it is important to keep the wing aligned while drilling. Firm pressure and constant checking of alignment is a good approach.
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- I use my cordless drill for this (NO GUIDE). Caution if you have not used a drill for this process.
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- This is temporary as to keep the wing square while drilling the remaining holes.
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- After drilling the pilot hole in the ply block, use a 10-24 tap to finish adding threads to this hole. Once done repeat the process for the second rear bolt before moving onto finishing the remaining 1/4-20 front bolt.
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- Remove the wing from the fuselage after confirming the alignment is good. Next drill clearance holes for all the wing bolts. Set the wing aside and work on the fuselage next.
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- Apply thin CA to all the tapped holes in the ply blocks. Allow the CA to fully dry before re-tapping the holes.
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- The black marks indicated the region to be removed to accept the front tab on the belly pan. I use a dremel and an end mill.
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- I use this hole to see the back of the firewall. I will discuss how to address the firewall and mount at the very end of this thread.
Re: MFL (CMAD) Build instructions
MFL cont:
Next I will work on the rudder horn and stab install. I use a long 3/32" drill bit (available from McMaster Carr) to open a passage through the hood molded into the fuselage. Once done I mark a center line for where the horn will be located using the drill bit and the bottom cut of the rudder for alignment. Next I prepare the supplied horn for installation. This requires some trimming and cleaning up. If you have a different method feel free to use it.
Next, I install the stabs and the elevator horn. Clean out the holes in the fuselage where the carbon rods pass through. I use a 3/16" bit backwards using my hand to clean out the holes. Don't get crazy here and use a drill, there is a small amount of flashing during the molding process that needs to be removed. If you have a 3/16" reamer this will work as well. Again install backwards and pull through the opposite hole to keep them aligned. Once the holes are free of flashing, I install both carbon rods. A slight bevel on the leading edges of the rods is helpful as well. These rods are too long in most cases and will need to be trimmed to length. I fit one stab 1/2 at a time. Install the carbon rods and work on one side first. Square up the root of the stab and the elevator clearance using whatever method that works for you. I use my 12" sander! A simple sanding block and some care should be used to obtain a good fit and enough clearance for the elevator to freely operate. Once the right 1/2 fits well I square up the left and then after both halves fit well I trim the rods. To trim the rods I fully seat the right 1/2 and push the rods through until they hit the stops molded into the stab. Only a small amount of force is needed here, don't push out the stops. Next slide the left stab onto the front rod only and measure the distance from the root to the fillet. This is the amount that needs to be trimmed off the rod. I use my Dremel and a cut off wheel to trim the carbon rods. Double check the fit before moving onto the rear rod and repeat the process for the rear carbon rod.
Next I will work on the rudder horn and stab install. I use a long 3/32" drill bit (available from McMaster Carr) to open a passage through the hood molded into the fuselage. Once done I mark a center line for where the horn will be located using the drill bit and the bottom cut of the rudder for alignment. Next I prepare the supplied horn for installation. This requires some trimming and cleaning up. If you have a different method feel free to use it.
Next, I install the stabs and the elevator horn. Clean out the holes in the fuselage where the carbon rods pass through. I use a 3/16" bit backwards using my hand to clean out the holes. Don't get crazy here and use a drill, there is a small amount of flashing during the molding process that needs to be removed. If you have a 3/16" reamer this will work as well. Again install backwards and pull through the opposite hole to keep them aligned. Once the holes are free of flashing, I install both carbon rods. A slight bevel on the leading edges of the rods is helpful as well. These rods are too long in most cases and will need to be trimmed to length. I fit one stab 1/2 at a time. Install the carbon rods and work on one side first. Square up the root of the stab and the elevator clearance using whatever method that works for you. I use my 12" sander! A simple sanding block and some care should be used to obtain a good fit and enough clearance for the elevator to freely operate. Once the right 1/2 fits well I square up the left and then after both halves fit well I trim the rods. To trim the rods I fully seat the right 1/2 and push the rods through until they hit the stops molded into the stab. Only a small amount of force is needed here, don't push out the stops. Next slide the left stab onto the front rod only and measure the distance from the root to the fillet. This is the amount that needs to be trimmed off the rod. I use my Dremel and a cut off wheel to trim the carbon rods. Double check the fit before moving onto the rear rod and repeat the process for the rear carbon rod.
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- Trim the horn as shown. The left horn is the final config as well as using a 1/16" drill to clean out the hole for the clevis.
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- Mask the area surrounding the cut-out and apply some JB weld Kwik in the hole.
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- I use a 12" length of 2-56 rod with a clevis to install the horn and ensure it is aligned correctly. Slide the rod into the hood to represent the rudder pushrod and place the horn into the filled hole. Check for squareness and clean up the excess glue. Masking tape is your friend.
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- Final representation of the rudder horn.
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Re: MFL (CMAD) Build instructions
MFL cont:
Once you are happy with how the stab fit, move onto elevator horn. The previous post shows how I would like to see the stabs fit the fuselage fillets. You should do your best to make these fit as tightly as possible to prevent any undue wear caused by ill-fitting stab 1/2s. One exception to the above pictures is the clearance for the elevators. Normally, there is a small gap that will prevent any binding. With the stabs in place mark the locations of the elevator joiner on the fuselage and make the appropriate cut outs. I use a Dremel and small endmill. The cut-outs should be big enough to prevent and binding or limited travel and yet be small enough that they don't blow through the fillets on the fuselage.
Next I move onto the assembly of the elevator joiner. BTW, this was designed by Jerry Small and created by Dub Jett, for those that think someone else created this part. There is a correct orientation to the joiner and care should be taken to mark and install it correctly. The 4-40 screws that lock the joiner into the elevator are at an angle. And the angle is representative of the head of the bolt being parallel to the surface of the elevator. This is critical to having the bolts match the surface of the elevator.
Once you are happy with how the stab fit, move onto elevator horn. The previous post shows how I would like to see the stabs fit the fuselage fillets. You should do your best to make these fit as tightly as possible to prevent any undue wear caused by ill-fitting stab 1/2s. One exception to the above pictures is the clearance for the elevators. Normally, there is a small gap that will prevent any binding. With the stabs in place mark the locations of the elevator joiner on the fuselage and make the appropriate cut outs. I use a Dremel and small endmill. The cut-outs should be big enough to prevent and binding or limited travel and yet be small enough that they don't blow through the fillets on the fuselage.
Next I move onto the assembly of the elevator joiner. BTW, this was designed by Jerry Small and created by Dub Jett, for those that think someone else created this part. There is a correct orientation to the joiner and care should be taken to mark and install it correctly. The 4-40 screws that lock the joiner into the elevator are at an angle. And the angle is representative of the head of the bolt being parallel to the surface of the elevator. This is critical to having the bolts match the surface of the elevator.
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- I break the upper corner of the joiner to make sure it sits flat into each elevator.
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- After breaking the corner trial fit the joiner into each elevator to make sure it sits flat.
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- Install the long 4-40 bolt temporarily to identify the correct orientation of the joiner.
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- the arrow in this picture points to the nose of the airplane and the plastic flag should point in that direction.
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- Remove the long bolt from the end and install into the center in the orientation shown, the jam nut is secured and tightened after the long bolt is tight. I use red loctite for this. Lastly install the flag matching the direction of the arrow.
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- This is the final assembled joiner with the flag in place. Note the direction of the arrow and the flag.
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- Install the joiner into the fuselage and fit both stab 1/2s onto the fuselage to make sure everything fits well.
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- I use #44 drill to pass through the bottom of the joiner and out the top to identify the location of the bolt. I only drill one 1/2 at a time, much like the wing. This allows for everything to fit tightly and securely without misalignment.
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- With the stabs installed, I place pressure on the near side with the far side up against my bench. This keeps the stabs tight and the joiner in the proper position. All the while drilling the hole on an angle using the #44 bit.
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- Remove the stab, and drill a clearance hole for a 4-40 bolt, I use a #32 bit.
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- Counter sink the top of the elevator to accept the 4-40 bolt
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- Place a bolt into the hole as you progress to make sure the flat head sits flush with the top surface. Go slow and it is better to have a shallow hole than a counter sink that is too big.
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- Install the first 1/2 securely.
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- Re-peat the process for the second 1/2. Apply pressure to the bench while drilling.
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- Most of the time the joiner requires some tweaking to fit properly. In this case the right elevator is high compared to the left.
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- Remove the joiner and use two crescent wrenches to tweak the joiner. Install and check for alignment. Repeat as necessary.
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Re: MFL (CMAD) Build instructions
MFL cont:
This space reserved for Firewall forward pictures.
This space reserved for Firewall forward pictures.
Re: MFL (CMAD) Build instructions
MFL cont:
The following set of pictures show the process I use for servo tray assembly and installation:
I assemble the supplied servo tray by adding balsa support to the back side. Two long strips of 1/4" triangle stock are glued to the bottom of the tray along the long sides to provide a larger gluing surface against the fuselage. The wide side of the triangle is glued to the tray using MED CA. Next, I install balsa backing blocks to the area where the servo screws pass through the tray. Lastly, I soak the edges of the tray and the holes with thin CA and set it aside to cure. Tom has some installation tools available that allow for proper position of the tray in both front to back as well as depth. I will add pictures in the future, next time I build one. Before installing my tray, I mark it's position in the fuselage relative to the tool shown below. I sand the sides of the fuselage with 80 grit and wipe clean with alcohol prior to gluing the tray in. Lastly, I install some 1/16" adhesive backed foam under the tray to prevent chaffing of wires against the glass. I use Shoe Goo to install my trays. I have found that, epoxy or hard mounting trays allows for vibration to attack servos and servo cases. The Shoe Goo is next to impossible to remove. If you haven't tried it I recommend it.
NOTE: if adding a charge jack utilizing small holes, make sure it doesn't pass through any carbon. If it is located near carbon, allow for the entire charge plug to exit the airplane. IF not, a fire will mess up your day.
While the main tray is set aside to dry. I work on the wing. The aileron tray is handled in the same manner. Balsa screw supports are added to the under side and the holes and edges are soaked with thin CA, set it aside to harden. Next use the install tool to mark the servo location and cut out the wing to accept the servo. Add the vertical support to the servo tray as shown. This support is used to prevent the lower skin from collapsing around the servo. The tray is centered in the opening and glued in place using 5 min epoxy and microballoons. Once dry I move on to finishing the torque rods.
Mark the bottom skin and make a clearance hole for the 4-40 x 1.25" bolt to pass through. Add a hole near the end of the torque rod to gain access to adding JB weld to the torque rod during the assembly process. Clean up the top skin to allow clearance for a nut driver and a 4-40 nut. Install the screw and nut while the JB weld is curing. Make sure everything is tight and set aside to dry.
The following set of pictures show the process I use for servo tray assembly and installation:
I assemble the supplied servo tray by adding balsa support to the back side. Two long strips of 1/4" triangle stock are glued to the bottom of the tray along the long sides to provide a larger gluing surface against the fuselage. The wide side of the triangle is glued to the tray using MED CA. Next, I install balsa backing blocks to the area where the servo screws pass through the tray. Lastly, I soak the edges of the tray and the holes with thin CA and set it aside to cure. Tom has some installation tools available that allow for proper position of the tray in both front to back as well as depth. I will add pictures in the future, next time I build one. Before installing my tray, I mark it's position in the fuselage relative to the tool shown below. I sand the sides of the fuselage with 80 grit and wipe clean with alcohol prior to gluing the tray in. Lastly, I install some 1/16" adhesive backed foam under the tray to prevent chaffing of wires against the glass. I use Shoe Goo to install my trays. I have found that, epoxy or hard mounting trays allows for vibration to attack servos and servo cases. The Shoe Goo is next to impossible to remove. If you haven't tried it I recommend it.
NOTE: if adding a charge jack utilizing small holes, make sure it doesn't pass through any carbon. If it is located near carbon, allow for the entire charge plug to exit the airplane. IF not, a fire will mess up your day.
While the main tray is set aside to dry. I work on the wing. The aileron tray is handled in the same manner. Balsa screw supports are added to the under side and the holes and edges are soaked with thin CA, set it aside to harden. Next use the install tool to mark the servo location and cut out the wing to accept the servo. Add the vertical support to the servo tray as shown. This support is used to prevent the lower skin from collapsing around the servo. The tray is centered in the opening and glued in place using 5 min epoxy and microballoons. Once dry I move on to finishing the torque rods.
Mark the bottom skin and make a clearance hole for the 4-40 x 1.25" bolt to pass through. Add a hole near the end of the torque rod to gain access to adding JB weld to the torque rod during the assembly process. Clean up the top skin to allow clearance for a nut driver and a 4-40 nut. Install the screw and nut while the JB weld is curing. Make sure everything is tight and set aside to dry.
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- Balsa is added for extra support of the servo screws
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- CA soaked tray for stiffness
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- Better picture coming.
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- This is purchased from McMaster Carr, #8722K23
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- This tool is positioned from the back of the firewall to the LE of the servo tray. It represents 8.375" back.
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- I add fillets of Shoe Goo to the top side of the tray
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- The tool shows using the notch marked "B" to place the servo in the wing as referenced from the TE flat at the center.
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- Cut enough material away to allow the entire servo including ears to pass through. This is centered in the wing. One 1/2 of the tray is glued in place and is allowed to pass into the second 1/2 of the wing when joined.
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- I install the tray using 5 min epoxy and microballoons into the right panel. The vertical support is added prior to installation and is trimmed to fit the bottom skin. This allows for the aileron servo to be completely installed into the right panel and the left panel is removable by simply disconnecting the clevis from the torque rod.
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- Dremel a hole near the end of the torque rod at the root to allow access to the end of the troque rod. Next use a #44 drill to drill through the torque rod through the bottom skin to position a hole for the 4-40 bolt that will actuate the aileron.
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- Clean up the hold on top of the wing near the torque rod. This needs to be big enough for a 4-40 nut and nut driver.
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- Create a larger hole in the bottom skin to allow the long 4-40 both to pass through the bottom skin
- MFL torque rod clearance bottom.JPG (29.68 KiB) Viewed 399 times
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- Partially tighten the 4-40 bolt and nylon insert nut as shown. Note the screw is angled backwards to allow for the white plastic flag to centered on the hinge line. I do not use differential.
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- Lastly, mix up some JB weld Kwik and feed some into the end of the torque rod. Fully tighten the screw and nut before the epoxy dries. NOTE, the screw is threaded into the aluminum torque rod and therefore it is important to tighten the screw fully and lastly tighten the nut on top.
Re: MFL (CMAD) Build instructions
MFL cont:
One scary task is drilling pilot holes for landing gear. Scary, because if you have ever done it, you probably drilled through the top skin. Yep, I have been there did it. SO, I created a 3D printed drill block to act as a drill stop and place the holes in the proper place.
I use a #49 drill bit along with my 3D printed block to drill all the pilot holes for the landing gear.
One scary task is drilling pilot holes for landing gear. Scary, because if you have ever done it, you probably drilled through the top skin. Yep, I have been there did it. SO, I created a 3D printed drill block to act as a drill stop and place the holes in the proper place.
I use a #49 drill bit along with my 3D printed block to drill all the pilot holes for the landing gear.
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- Set the depth of the dril bit so that it exits the block about 1/8", not enough to exit the top skin.
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- Place the block in the recess of the wing and drill all 4 pilot holes. Care should be taken to keep the block located properly in the hole
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- The block provides a positive stop while drilling.
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Re: MFL (CMAD) Build instructions
Dan Kane invited me to chime in here on his Miss Foxy Lady build thread to illustrate a fuel tank “wedge and cradle” mounting system that some of us use. I’m not certain, but I believe this was originally conceived by Richard Beers and then adopted by Dub. Dub showed it to me. Because I have a CO2 laser cutter, I took the idea and ran with it reproducing parts and evolving the design over time. The main thing I like about this semi-rigid mounting setup is, simply, I just find it easier than the other ways of holding in a fuel tank such as Velcro and/or tape and foam. With this wedge and cradle, the tank is kind of locked into place. Initial installation requires more work and prep in the shop at home, but out in the field at the races it has been 100% maintenance-free. It’s also repeatable which may be good for the Jett engine because apparently, fuel tank location/height is more critical with the Jett. The height of the wedge has also evolved to position the tank at the correct height for the best runs with a Jett engine. At this moment, I’m not sure who out there is running this setup, though I know Dub is and all my MFLs are set up this way (for whatever that is worth). I have also made these parts for some others. I am not necessarily advocating this setup. It’s just what I use and Dan asked me to share it here.
On the MFL, first thing that has to be done is grind away the glue bead in front of the canopy. I CAREFULLY use a Dremel with a sanding drum followed with sandpaper by hand. I then reinforce the joint with a strip of lightweight glass cloth and resin.
Next, prepare the tank. Dub favors the Jett 6 oz. slim, round tank and that’s what I use. I wrap the aft end of the tank with a couple wraps of kapton tape, an anti-abrasive tape for electronics. I then glue together the parts of the wedge (comprised of two outer pieces of lite-ply and two inner pieces of 1/8” balsa) and use Shoe Goo/Zap Goo/E6000 to glue the wedge to the top of the tank (the sticker noting the top of the tank).
The cradle is shaped to fit the fuselage and position the aft end of the tank about 4-12” to 4-3/4” aft of the wing LE. This also allows the servo tray to be positioned about 1/8” behind the tank for tank removal/installation. Use more Zap Goo to glue the cradle into the fuselage temporarily setting the tank and wedge into place to perfectly position the cradle.
From Tim Lampe
On the MFL, first thing that has to be done is grind away the glue bead in front of the canopy. I CAREFULLY use a Dremel with a sanding drum followed with sandpaper by hand. I then reinforce the joint with a strip of lightweight glass cloth and resin.
Next, prepare the tank. Dub favors the Jett 6 oz. slim, round tank and that’s what I use. I wrap the aft end of the tank with a couple wraps of kapton tape, an anti-abrasive tape for electronics. I then glue together the parts of the wedge (comprised of two outer pieces of lite-ply and two inner pieces of 1/8” balsa) and use Shoe Goo/Zap Goo/E6000 to glue the wedge to the top of the tank (the sticker noting the top of the tank).
The cradle is shaped to fit the fuselage and position the aft end of the tank about 4-12” to 4-3/4” aft of the wing LE. This also allows the servo tray to be positioned about 1/8” behind the tank for tank removal/installation. Use more Zap Goo to glue the cradle into the fuselage temporarily setting the tank and wedge into place to perfectly position the cradle.
From Tim Lampe
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- Here, glass cloth and resin after the glue bede has been ground off.
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- The aft end of the tank has been protected with kapton tape and the wedge glued to the top. (This is a wedge from a different plane because the wedge for the MFL is taller.)
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- Here, the tank and wedge are used to position the cradle to be glued into the fuselage. Be certain to leave space aft of the tank for your servo tray.
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- Here's the cradle in position.
Re: MFL (CMAD) Build instructions
Continuing with tank installation, cut some foam wedges to keep the front of the tank centered. Again, I use Zap Goo to glue in these wedges. One more piece of foam is used to hold the tank up when the wing is mounted.
Tim Lampe
Tim Lampe
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Re: MFL (CMAD) Build instructions
Note: after grinding the seam away and sanding the inside of the fuselage, it is a good idea to add some clear tape to the outside of the fuselage to prevent glue from running out on the outside. I have learned the hard way, and now this is a common practice when grinding seams or adding epoxy to the inside of a finished fuselage.
Tim: Thank you for the awesome picts!!!
Tim: Thank you for the awesome picts!!!
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Re: MFL (CMAD) Build instructions
Dan asked me to comment on battery placement and fuel line routing. Well, battery location (and servo tray location) can very much help with C.G. to minimize any additional nose or tail ballast to achieve the desired C.G. I’ll let Dan talk about the recommended C.G. location, but I strive for about 2-15/16” to 3” (aft of the wing leading edge at the middle of the wing). With a Jett engine, this C.G. can be achieved by putting the battery (I use a 2S 6.6V LiFe) in the nose in the space behind the firewall and ahead of the cutout for the wing. I use epoxy to glue in a battery plate made from lite-ply and attach the battery with Velcro. The plate is sized to fit a battery while also being low enough to not interfere with the fuel tank or lines.
I’ll note again that, even I admit that some of the methods I use seem to be more complicated than necessary. I know other guys use a popsicle stick on the fuel tank or foam to stuff the battery in the nose, but also again, I don’t mind spending extra time in the work shop if it prevents issues at the races and this is what works for me.
Tim Lampe
I’ll note again that, even I admit that some of the methods I use seem to be more complicated than necessary. I know other guys use a popsicle stick on the fuel tank or foam to stuff the battery in the nose, but also again, I don’t mind spending extra time in the work shop if it prevents issues at the races and this is what works for me.
Tim Lampe
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- The slot in the back of the battery plate is filed to a bevel to accommodate the fuide tube for the fuel cut wire.
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- I place the velcro on top of the battery plate with CA before gluing the plate in.
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- I use a piece of foam cut at an angle to hold in the battery plate until the glue hardens.
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- Here's the foam holding in the battery plate.
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- Installation complete.