30 January 2021 at 5:55 PM #740
Next job to do was a check of the CG of the model and as I expected, she is tail heavy. Even with the 6S Lipo as far forward as it would go, further forward even than the battery tray, it would still require nose weight. So what can I do about it? There are some options:
- Rudder servo is mounted at the rear but there is a slot for it to be mounted in the normal place under the canopy area, so move it.
- Reinforce landing gear area as mentioned before to add strength and weight.
- Run a separate battery for the avionics, adds weight and redundancy.
Hopefully that will bring the CG into limits. Gratuitous outside shot taken during the CG check….
1 February 2021 at 9:52 PM #744
- This reply was modified 1 year, 5 months ago by Brookes745.
So the first part of operation “move the CG” is to move the rudder servo forward from the tail into the pre-cut slot on the fuselage and to convert to closed lop control. Interestingly all the hardware to do this is included with the kit. Rudder servo in its new home…..note the fuel tubing keepers that will be pushed into place when everything is finally adjusted.1 February 2021 at 9:53 PM #745
Next a second arm was added to the rudder and the closed loop system connected up.1 February 2021 at 9:54 PM #746
Another shot of the linkage……5 February 2021 at 9:28 PM #750
Next up was to strengthen the landing gear to add a bit more weight forward of the CG. Ply doublers were added to the balsa faring’s and 2mm glass fibre board reinforcing plates made up to glue directly to landing struts.5 February 2021 at 9:29 PM #751
Then masked and sprayed blue….5 February 2021 at 9:30 PM #752
And finally fitted using epoxy……5 February 2021 at 9:34 PM #753
Next step was to do another balance check with the LiFe receiver battery and flight battery in place. results showed that had sufficient room to mount the LiFe to achieve correct balance. Did it cheekily in the front room while wifey was at work as it was raining outside…….model shown here fully assembled on my stand waiting to go on the balance rig.5 February 2021 at 9:36 PM #754
Battery shown in position below motor mount…it will be under the cowl but being a LiFe I’ve no worries about charging it in situ….5 February 2021 at 9:40 PM #755
The receiver was mounted in place. To leave the flight battery bay as clear as possible I made a removable platform above the rudder servo. Note the two satellites lit up as well as the receiver and one of the two aerials pointing upward in a tube….5 February 2021 at 9:43 PM #756
A separate switch was mounted to connect the receiver battery. The lead from the ESC had the red power connector de-pinned so power will only come from the receiver battery……6 February 2021 at 8:09 PM #757
Sticky velcro added to the battery and the bay floor to hold the flight battery firmly in place along with velcro straps…..6 February 2021 at 8:13 PM #758
Next up was to fine tune the controls. The best way to do this and make sure that everything is bob on, is to do it off the aircraft, on a jig.6 February 2021 at 8:16 PM #759
Basically the jig involves a piece to wood with holes in it to hold the tail plane or wing halves in place along with the joiner tube. The neutral points can then be accurately measured and adjusted.6 February 2021 at 8:21 PM #760
Same process with the ailerons. Both surfaces are set to 40 degrees of movement full deflection but for normal flight they are set to 30% on the rates. This gives a deflection of about 15mm at the TE. 100% is only used for spinning and all the rates for all the surfaces are controlled off one switch.
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