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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