A comment worth adding to the tailwheel mod saga in general (not to
this posting in particular) is that we at Europa carried out a lot of
taxiing/ take-off/ landing trials with various geometries of tailwheel
assy, some of which were calculated and others which were developed from
the trials. The final design is a result of all these trials and the
continuing experience being gained on both of our mono-wheel aircraft.
This is not to say that other solutions won't work, but bear in mind
that somewhere the theory has to stop and the practical take over.
Regards - Andy
>For those who are still interested in tailwheel geometries and are not
>thoroughly bored by it all, I should point out that the program produced
>answers for positive ( aft going deflections of the input arm ) as well as
>negative going (pulls). Aft dellections would only be meaningful if the
>coupling was by a rod, not a cable. One really only needs the full
>deflection when the input arm is pulled against the 45 deg. stop. These are
>easlily tabulated.
>
>TAILWHEEL MOD. DESIGN OPTIONS
>for Input angle -45 deg.( pull )
>Coupling dist 942 (typical) Wheel horn rad. 63.5 (Europa)
>Wheel arm offset 25 mm.(Europa)
>
>Input arm offset 0 (at the old wheel position)
>
>Input arm rad. Output angle deg. Slack mm. in other cable.
> 60 -39 14
> 65 -42 15
> 70 -45 17
> 75 -48 19
> 80 -52 21
> 85 -56 24
> 90 -60 26
> 95 -64 28
>
>Any matching offest on the input loses deflection (though it is somewhat more
>linear)
>
>Input arm offset 12
>
> 60 -30 26
> 65 -33 28
> 70 -36 30
> 75 -39 31
> 80 -43 33
> 85 -46 35
> 90 -50 37
> 95 -54 39
>
>Europas 25mm offset certainly gives some gain in sensitivity when not running
>straight, if that is what is needed, and I imagine not many will want to
>modify their wheel arm to make it otherwise. But if you do use zero
offsets on
>both arms, clearly with both at 63.5 you will get 45 output with no slack.
An
>80 mm radius input arm will give 60 deg output with just a few mm. slack,
>which will easily be absorbed by the springs.
>
>Incidentally the old tail wheel post provides a simple way of making a lower
>arm without hacking out thick plate. Just insert a 3/8" steel rod through the
>old bracket, and hook the cable ferrules over the ends, trapping between
>washers held by split pins. Easy to adjust too with spacer tubes.
>
>Graham C G-EMIN
>
>
>
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