120 mm EDF by tahustvedt

Last crawled date: 3 years ago

The EDF that powers my EL-39 3D printed jet: https://youtu.be/9tShEHO5M5shttps://cults3d.com/en/3d-model/various/el-39-semi-scale-rc-jet-for-120-mm-edf
I recommend a 120 A ESC and 12S lipos. Expect 85-100 A current draw. I haven't measured max thrust as my thrust stand maxes out at 5 kgf.
the photos show the fan with rubber inlet and exhaust installed. It will be shorter without them.
Safety warnings:
-This is a very highly loaded assembly at high speed so it's important that you know what you are doing.
-Make sure the integrity of the printed impeller is good before trying to run it.
-Always wear protective glasses when test runnin the fan. Always protect your eyes.
-Do NOT run the fan at high power while holding in your hand.
-Keep your hands and any loose items away from the fan when running. It WILL shred your fingers if they get sucked in, and the suction force is very strong. If something gets sucked in it can damage the impeller and potentially shatter, throwing loose debris out.
To secure the fan to the motor it is recommended that you drill a 3 mm hole half way through the shaft 17 mm from the motor mounting face so that one grub screw is driven by the motor. A flat spot is probably not enough to keep it on due to the softness of the plastic.Use two grub screws. A high quality carbide drill and a drill press makes drilling the hole easy. Regular HSS drills will struggle to cut the shaft.
If the fan rubs when new it will usually stop rubbing after slow speed running for a few seconds. If the interference between the fan and shroud is great then you'll need to sand the blades slightly until it spins freely. The ideal fit is when the fan barely touches some places when new, and rubs itself to a very close fit after a few seconds.
Use thermal paste between the motor and heatsink. I recommend a good quality thermal paste for PC CPU heatsinks.
Use thread locking compound on the motor mounting bolts.
I recommend balancing the fan statically before running, and then balancing by feel while running slowly. Use aluminum tape on the respective blades to balance the fan.
The tail cone should be glued to the end of the motor using CA. Use heatshrink tubing around the motor wires so that they form a slim shape fr less air resistance.
The bell intake is for test running on a test bench. Running without the bell intake produces artificially low thrust.
Expect 4,2 kW in a test bench and 3,8+ kW installed in an airframe.
It needs a HET 800-73-590kv motor with a heatsink:https://www.effluxrc.com/HET-800-73-590-Motor-8mm-shaft-HET800-73-590-8MM.htmhttps://www.effluxrc.com/Jetfan-120-1-Heat-Sink-for-50mm-Motors-JF50mmHS-1.htm
M3x20 grub screws for securing the impeller to the shaft:https://rover.ebay.com/rover/1/711-53200-19255-0/1?ff3=4&toolid=11800&pub=5575353675&campid=5338226872&mpre=https%3A%2F%2Fwww.ebay.com%2Fitm%2FM3x20mm-12-9-Alloy-Steel-Hex-Socket-Set-Cap-Point-Grub-Screws-Black-20pcs%2F351462953237
M3x8 countersunk screws for attaching the motor to the housing:https://rover.ebay.com/rover/1/711-53200-19255-0/1?ff3=4&toolid=11800&pub=5575353675&campid=5338226872&mpre=https%3A%2F%2Fwww.ebay.com%2Fitm%2FM3x8mm-10-9-Carbon-Steel-Countersunk-Head-Hex-Socket-Screw-50pcs-T7M8%2F253244968159
Thermal paste for the heatsink:https://hobbyking.com/en_us/thermal-heat-transfer-compound-with-applicator-2pc.html?affiliate_code=BSFWYBUNYWDKXJN&_asc=8924049282https://rover.ebay.com/rover/1/711-53200-19255-0/1?ff3=4&toolid=11800&pub=5575353675&campid=5338226872&mpre=https%3A%2F%2Fwww.ebay.com%2Fitm%2FArctic-Artic-Silver-5-Thermal-Compound-Paste-FOR-Grease-CPU-Heatsink-XBOX-PS4%2F263410160737