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Old Jan 14, 2013, 08:01 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
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MJX F45 basic Mods

FWIW, my own ‘must do’ new F45 checklist (after initial hover test) - all page Nos refer to main F45 thread:
1) Install flybar bumper on main boom
2) ‘Paperclip and epoxy glue’ reinforcement of buckle (dogbone) loop guides on rotor head (see p184) – Or Hinnerk’s full rebuild mod when they fail (same page). Done both, on different F45s.
3) Check insulation around the main motor terminals – add heatshrink (or tape) if faulty. The canopy pushes hard on these wires, and a short here will total the FET on the main PCB instantly. Others have reported – and I’ve noted one of mine - coming OoTB with damaged insulation.
4) Anchor the PCB to support struts with glue gun. Similarly anchor other subassemblies to main PCB. Particularly gyro, if not flat type.
5) Remove at least 3 of the 5 tailrotor motor cover supports for improved airflow.
6) (nice, but not essential) Solid rod replacement for tube landing gear skids (the stock tube cracks very easily in front of the forward skid support). Or shove aluminium coathanger wire up stock skids to reinforce.

And for better fff, at the expense of a little stability –
7) Shim both blades (3-4 plastic binder reinforcement rings on each blade work well). The blades should be (only just) able to turn the rotor without shifting.
8) Remove horizontal stabiliser and support tubes from the boom. Add an equivalent weight (about 10g) of Bostik blu-tack (or hot glue) inside the nose tip of the canopy - OR fit a longer LiPo as suggested in previous posts, which equally effectively shifts the CoG forward.

Finally, and more contentious here!
9) If free flights are going to be consistently over 6 mins, or hovers over 3-4min, fit heatsinks to both motors. Within these limitations, however, I have noticed no difference in motor MTBF between one of my F45s with heatsink, and another without. You get around 4- 8h runtime, either way (but of course, YMMV).
However, I do agree that with long flight durations in high ambient temperature, it may be possible to destroy one of the brush support arms before the brush wears out, leading to very premature failure. Heatsinks here may tip the balance, unless they occlude the motor ventilation holes.
TL, DR? An awesome <$100 heli, but get spare motors. Or go brushless.
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Last edited by OldOz; Jan 14, 2013 at 08:08 AM.
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Old Feb 23, 2014, 08:31 AM
Registered User
Joined Jan 2014
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don't see a reference as to what this flybar bumper is?

Hi OldOZ
I have several F45's and am making your suggested mods. I see a reference to
1) Install flybar bumper on main boom - but no picture or description. Could you point me in the right direction please.

Thanks
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