[Graeme Smith]

Well here it is the drawings for the RW t/r drive assembly.

[Lyle Swallows]

just thought of another solution for pitch horns

placing the pitch horns counterweight on the inboard side of the tail rotor while placing the pitch horn on the leading edge of the tail rotor blade is a free solution.

keeps the same positive pitching moment the counterweight is intended for (to increase pitch with RPM) stays close to factory, there isnt a clearance issue as the rotorway scorpions had the counterweights on the inside, (that TR was setup as a puller/tractor tailrotor where as ours is a pusher)

but now the pitch horns on the leading edge creating a control reversion at the pedals, so a bellcrank flip and control cable tab welded onto the frame similar to the cyclic cable. this gets rid of the big standoff for the pedal cable which i've never liked, and keeps the routing of the cable neat and tidy, which i like.

thoughts?
one negative i can see is the tail rotor cable will constantly be in compression instead of tension with right pedal applied, but this should be a very negligible difference.

[Graeme Smith]

We printed the secondary gearbox the 










to check the fit etc, it does show the existing 1/4" bolt holding the gearbox onto the secondary bare shaft. the red tubes are the #6 oil lines coming from the bottom of the gearbox where there is a geo rotor oil pump, the idea is as the gearbox is mounted vertically the oil would not get up to the output bearings or the top bearing so the pump circulates the oil and that oil travels through an oil filter which has a clear inspection window that you can visually see if the filter has debris in it

[Lyle Swallows]

so the original lower secondary bearing when loosened allows for angular adjustment for alignment, does this allow for any alignment? i can see laterally due to slotting of the holes but it otherwise has to be shimmed to the same level of precision as the upper bearing for longitudinal alignment, correct?

[Graeme Smith]

so the original lower secondary bearing when loosened allows for angular adjustment for alignment, does this allow for any alignment? i can see laterally due to slotting of the holes but it otherwise has to be shimmed to the same level of precision as the upper bearing for longitudinal alignment, correct?

yes that is the design, shim to keep the correct tension on the drive belt and shim the sec gb to match it the bolt slots in the SEC GB have an up / down tolerance but not side to side

[Graeme Smith]

We are nearly at the end so here is some snapshots or the TR GB. This setup will fit on any RW boom and with the talon the existing shaft drive could be slightly modified to drive this GB as well, I would need to know more about the input RPM of the talon shaft drive as I have no specs at all only seen some drawings and photos.
This model has been designed to accept a tail shaft rpm of 2487, and it steps up the tail rotor shaft output to 2860rpm

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here is some views of the Secondary gearbox, it mounts on the shaft coming from the secondary, (where the drive TR vee belt pulley mounts, This only works if the belt driven fan and top radiator shroud is removed and my outside scoops and top shroud replaces them

[Graeme Smith]

Well I am at that point totally satisfied with the design, have an experienced aviation company to do the machining and 4 orders, now is the time if anyone has an interest in upgrading to a shaft drive with aviation designed gearboxes and more tail rotor authority, The design uses the standard RW tail rotor blades and connects to the secondary lower shaft, and included in the fkit are 2 reverse pitch horns.

The changes needed to fit the secondary gearbox require the existing Radiator fan to be removed and its shroud and a new shroud replaces it. An electric fan is mounted on the bottom of the radiator, side scoops capture air when in forward flight. The gain in more useable power by deleting the fan saves approx 10hp, the electric fan on the bottom of the radiator consumes approx 1.5 - 2.0hp so you have a net gain of 8hp, BUT when in forward flight the scoops capture the air thus the fan remains off, only in the hover does the fan turn on then it cycles as needed.

So an extra 8hp from the fan swap
and the losses in the belt drive system from Ai amount to...
std Vee belts loose approx 4-6% this consumes about 1.5% per belt so total 0.6 -0.9HP
twist and misalignment 8% - 12% loss 1.2 - 1.8HP loss...... so a loss of 1.8 - 2.7hp in vee belt loses, 
Again from Ai a R22 TR gearbox loss is approx 0.15 - 0.3 hp
so our 2 gearboxes should loose approx 0.3hp - 0.6hp a saving of 1.5 - 2.1HP 
also our design spins the TR blades a little faster and spins them the opposite way again both add efficiencies which equate to more TR authority and less hp losses.
Thus a saving in total of approx 9HP and a cooling system that works.
Rule of thumb in helicopter performance is 1HP will lift 10lbs,

This from Ai re benefits of anti clockwise rotation

Spinning the tail rotor so that the advancing blade moves up into the main rotor downwash provides two major aerodynamic benefits:
1. Increased Efficiency and Thrust
Higher Relative Airspeed: Because the blade is moving upward against the downward-rushing air of the main rotor, the total velocity of the air over the blade increases significantly.
Greater Anti-Torque Authority: This increased airspeed allows the tail rotor to produce more lift (thrust) with less engine power, granting the pilot superior yaw control.
2. Reduced Vortex Ring State (VRS) Risk
Altered Induced Flow: When a tail rotor blade moves down with the downwash, it operates in highly turbulent, recirculating air that mimics a micro-vortex ring state.
Stable Aerodynamics: Moving up against the downwash pushes the blade into a cleaner, more predictable airflow stream, preventing a sudden and dangerous loss of tail rotor effectiveness (LTE).

[Geno Mancini]

Graeme,
I have in my notes the Talon tail rotor spins at 2649.
Someone who has balanced one, could confirm that rpm.
Both gear boxes are 1.5 ratio.
That would put the input shaft at 1766 (2649/1.5)
I like the slower input speed (1766) then kick it back up to 2649.

[Graeme Smith]

Graeme,
I have in my notes the Talon tail rotor spins at 2649.
Someone who has balanced one, could confirm that rpm.
Both gear boxes are 1.5 ratio.
That would put the input shaft at 1766 (2649/1.5)
I like the slower input speed (1766) then kick it back up to 2649.

Hi Geno,
we went for a closer ratio, only a couple of teeth different this helps spread the tooth wear as it is not the same teeth being engaged all the time, I think it is called hunting tooth set up.
and we are restricted by the speed of the secondary shaft, as that is the shaft that drives the sec GB.