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Magnus Electric Build Thread
- Thread starter Lothar
- Start date
Lothar
User
Motor firewall.
Regarding the addition of side and down thrust, the consensus in the RCGroups High Performance forum seems to be to use 0,0 contrary to what you might expect when using a high power high torque setup. Example thread https://www.rcgroups.com/forums/showthread.php?155474-f5B-Hotliner-Side-Downthrust
First step is to modify the firewall to suit the Typhoon 4W-25, which has offset mounting holes to make room for cooling vents:
Regarding the addition of side and down thrust, the consensus in the RCGroups High Performance forum seems to be to use 0,0 contrary to what you might expect when using a high power high torque setup. Example thread https://www.rcgroups.com/forums/showthread.php?155474-f5B-Hotliner-Side-Downthrust
First step is to modify the firewall to suit the Typhoon 4W-25, which has offset mounting holes to make room for cooling vents:
Konrad
Very Strong User
Love the details! 7mm pocket does seem to be forcing the placement of 8mm servos as far forward as the spar will allow. Based on the quality of Magnum, high end servo would be justified.
Wow, the fuselage looks like it will hold large batteries. This looks to be a departure from what I'm are use to seeing with say F5D ships.
Can you please focus a bit on the battery compartment, servo placement and CG requirements when you get to that part of the build?
Love the inrunner motor. What cell count (4)?
On the ideas of down thrust. The F5B thrust lines are aimed for ships that go in the vertical. That is there is no "P" factor from the asymmetrical prop thrust like we get in a sport ship. In a sport ship (one flying on the wing) the air flow into the prop is from (determined by) the angle of attack of the lifting wing. In a vertical climb the wing is not generating lift therefor the thrust can be (0-0). I still add a bit of down and right if for no other reason than I don't want up or left thrust.
On the firewall I recall Aloft had some. I wonder why the holes are so narrow on the TJIRC units?
All the best,
Konrad.
P.S.
Thank you for the fine OpenTX manuals. You have saved my hairline!
Wow, the fuselage looks like it will hold large batteries. This looks to be a departure from what I'm are use to seeing with say F5D ships.
Can you please focus a bit on the battery compartment, servo placement and CG requirements when you get to that part of the build?
Love the inrunner motor. What cell count (4)?
On the ideas of down thrust. The F5B thrust lines are aimed for ships that go in the vertical. That is there is no "P" factor from the asymmetrical prop thrust like we get in a sport ship. In a sport ship (one flying on the wing) the air flow into the prop is from (determined by) the angle of attack of the lifting wing. In a vertical climb the wing is not generating lift therefor the thrust can be (0-0). I still add a bit of down and right if for no other reason than I don't want up or left thrust.
On the firewall I recall Aloft had some. I wonder why the holes are so narrow on the TJIRC units?
All the best,
Konrad.
P.S.
Thank you for the fine OpenTX manuals. You have saved my hairline!
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Lothar
User
I am glad you find my manuals useful. The first one for X9D+ took 15 months of all my spare time to write. The X7 variant took another 4, then the X10 another 5. The maintenance has tapered off a bit, until the next big release.
Your comments about thrust make sense, so I will add 2 + 2 deg. I will use an aluminium bar held against the front opening to set these. The diameter of the opening is 36mm, so for down thrust I need to file a channel SIN(2*PI()/180)*36 = 1.3mm deep. The bar is 10mm wide, so for side thrust I need to file an angle of SIN(2*PI()/180)*10 = 0.3mm.
Your comments about thrust make sense, so I will add 2 + 2 deg. I will use an aluminium bar held against the front opening to set these. The diameter of the opening is 36mm, so for down thrust I need to file a channel SIN(2*PI()/180)*36 = 1.3mm deep. The bar is 10mm wide, so for side thrust I need to file an angle of SIN(2*PI()/180)*10 = 0.3mm.
Lothar
User
Space in the fuselage:
The distance from bottom of the joiner bar to the outside bottom of the fuse is 50mm, which is also 50mm wide (outside) at that point.
The distance from bottom of the wing connector hole to the outside of the fuse is 45mm, which is 47mm wide (outside) at that point.
I plan to install an S8R Pro in front of the elevator servo, then the battery, motor and ESC in front.
Possible battery options for light to heavy conditions:
Dualsky
Capacity 2250mah 4S1P Dimensions (L x W x H) 108 x 44 x 33mm Weight 249g
Capacity 2700mah 4S1P Dimensions (L x W x H) 138 x 44 x 21mm Weight 269g
Capacity 3300 mAh 4S1P Dimensions (L x W x T) 140 x 44 x 22mm Weight 297g
Capacity 3700 mAh 4S1P Dimensions (L x W x T) 140 x 44 x 26mm Weight 355g
More on this once I can do a trial CG balance.
The distance from bottom of the joiner bar to the outside bottom of the fuse is 50mm, which is also 50mm wide (outside) at that point.
The distance from bottom of the wing connector hole to the outside of the fuse is 45mm, which is 47mm wide (outside) at that point.
I plan to install an S8R Pro in front of the elevator servo, then the battery, motor and ESC in front.
Possible battery options for light to heavy conditions:
Dualsky
Capacity 2250mah 4S1P Dimensions (L x W x H) 108 x 44 x 33mm Weight 249g
Capacity 2700mah 4S1P Dimensions (L x W x H) 138 x 44 x 21mm Weight 269g
Capacity 3300 mAh 4S1P Dimensions (L x W x T) 140 x 44 x 22mm Weight 297g
Capacity 3700 mAh 4S1P Dimensions (L x W x T) 140 x 44 x 26mm Weight 355g
More on this once I can do a trial CG balance.
Konrad
Very Strong User
That's one way to do it. I assume you will sand the nose later for an even spinner to fuselage gap.
I honestly use an inclinometer to measure the nose ring. Then use the spinner to set the angels and center the firewall.
As to a value this is highly dependent on weight and speed. Truth be told, it isn't unusual that I tear out the firewall or reset the nose several time during my flight tests.
TopModel Samsara 3.2 meter glider, build thread on Aloft's Forum.
WOW, are MKS servos expensive. Some background, while waiting for my radio's firmware to be updated, I had brought along an old FVK Brisk III which I had problems finding servos to fit in the rear servo pocket. I was allowed to roam the warehouse looking for servos that would fit. Out of...
forum.alofthobbies.com
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Lothar
User
Justification for choosing the Typhoon 4W-25 1360 kV in runner: I compared the 4W-24 to the Dualsky XM3040EG-9 1350kV on ecalc, and found that the 4W-25 seems to have a sweet on 4S with a 9x7 prop, giving thrust-weight of 1.95 and a pitch speed of 140km/h. The Dualsky went off the dial on 4S, and while good on 3S I opted for the 4W-25. And Wayne having it in stock made the choice easy.
Lothar
User
Yes, but I will fly it first to see if I am happy with the side & down thrust before sanding the node.
Lothar
User
Trial CG balance, with:
a) Centre of the ESC at 30mm from the front of the canopy opening, allowing plenty of room to get the battery in and pushed back under the wing.
b) Receiver with wiring harnesses all the way back to the elevator pod, allocated 75mm of space.
1. CG of plane without battery is at 126mm.
2. CG with 105mm long 200g battery all the way back under the wing up to the receiver = 115mm, so can balance by moving forward.
3. CG with 113mm long 253g battery all the way back under the wing up to the receiver = 113mm, so can balance by moving forward.
4. Largest battery that will fit TBD - required trip to the local hobby store.
Basically I can use from a light 150g battery in light conditions, right up to the heaviest battery that will still fit when needing ballast.
a) Centre of the ESC at 30mm from the front of the canopy opening, allowing plenty of room to get the battery in and pushed back under the wing.
b) Receiver with wiring harnesses all the way back to the elevator pod, allocated 75mm of space.
1. CG of plane without battery is at 126mm.
2. CG with 105mm long 200g battery all the way back under the wing up to the receiver = 115mm, so can balance by moving forward.
3. CG with 113mm long 253g battery all the way back under the wing up to the receiver = 113mm, so can balance by moving forward.
4. Largest battery that will fit TBD - required trip to the local hobby store.
Basically I can use from a light 150g battery in light conditions, right up to the heaviest battery that will still fit when needing ballast.
Lothar
User
Elevator horn install.
I agree that the 2.4mm Dremel tungsten carbide 9904 cutter is the best option for cutting slots if the width is compatible. I would have preferred a 2mm cutter, but I have found that the Engraving Cutter 0,8 mm (111) tends to pull itself into the material causing it to veer off course.
I used 30min epoxy mixed with West Systems filler.
Notice the packing tape on one side to protect the stab surface during installation.
I agree that the 2.4mm Dremel tungsten carbide 9904 cutter is the best option for cutting slots if the width is compatible. I would have preferred a 2mm cutter, but I have found that the Engraving Cutter 0,8 mm (111) tends to pull itself into the material causing it to veer off course.
I used 30min epoxy mixed with West Systems filler.
Notice the packing tape on one side to protect the stab surface during installation.
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Lothar
User
Elevator servo mounting prep.
I am adding two short lengths of popstick from underneath on either side of the elevator servo opening, for the servo mounting screws to bite into.
I tacked a short length of skewer to the servo support pieces with CA, which allowed me to manoeuvre the supports through the opening after covering the mating faces with Clear Gorilla Glue. I looped a rubber band around the skewer and wrapped it around the fuselage to act as a clamp. Once the glue has cured, the skewer piece will be removed.
I am adding two short lengths of popstick from underneath on either side of the elevator servo opening, for the servo mounting screws to bite into.
I tacked a short length of skewer to the servo support pieces with CA, which allowed me to manoeuvre the supports through the opening after covering the mating faces with Clear Gorilla Glue. I looped a rubber band around the skewer and wrapped it around the fuselage to act as a clamp. Once the glue has cured, the skewer piece will be removed.
