Skid versus tailwheel on a Turbulent.

[abgd]

My Turbulent currently has a tailskid. Until now, I've always flown it from grass and found it pleasingly benign in terms of directional control during take-off and landing. However, I've just moved to a tarmac runway and given myself a scare when it started to ground-loop despite full opposite rudder - then saved itself by exiting the runway onto grass which it clearly preferred. No harm done. I went for another flight, and the same thing happened.

I was quite shaken - I did my tailwheel conversion on grass in a Cub and found it slightly more work than the Turbulent on grass, but I felt in-control. Now the incident was at least partly down to my lack of finesse with the pedals - and I find the brakes downright awkward - but before I take to the air again I find myself wondering whether what I was trying to do was silly anyway.

The questions I have in my mind are:

1) How hard is it to land a tailskid aircraft on a hard surface? i.e. is this advanced 'conventional gear' flying in which case I can perhaps forgive myself for letting it get away? Or do I really need to look at my technique? Conditions were reasonably benign at the time. The Turbulent is known for being quite light on the tailskid so it really doesn't provide anything in the way of an anchor.

2) Will a fully castoring tailwheel give me much more directional control on a hard surface than a tailskid? There are no springs or detents to keep it centered, though presumably as it is trailing it still acts to damp down any divergence better than a skid would do.

In the meanwhile, grass whenever possible...

[ExSp33db1rd]

1) How hard is it to land a tailskid aircraft on a hard surface? i.e. is this advanced 'conventional gear' flying in which case I can perhaps forgive myself for letting it get away? Or do I really need to look at my technique? Conditions were reasonably benign at the time. The Turbulent is known for being quite light on the tailskid so it really doesn't provide anything in the way of an anchor.

2) Will a fully castoring tailwheel give me much more directional control on a hard surface than a tailskid? There are no springs or detents to keep it centered, though presumably as it is trailing it still acts to damp down any divergence better than a skid would do.

In the meanwhile, grass whenever possible...

I can't really answer your question, never having flown a Turbulent with a skid, mine has centering springs to help keep the wheel straight, which moves a little bit with the rudder, too, but as I didn't build the beast I don't know when they were fitted, but I "think" as an afterthought.

I took delivery after about a 45 year gap from having last flown a taildragger, and decided not to take on the crosswind on my airport's hard runway for my first re-acquaintance, so used a very short grass runway more into wind.

I was pleased with my touchdown, which was straight, but then the far hedge began to appear and I experimented with the brakes. My brakes stand up between the rudder pedals and it is easy to apply both brakes with one foot, in fact it is impossible to get both feet on their respective pedals anyway, but of course they are never rigged equally so a turn is induced, this then requires a bit of rudder and brake on the other side, and it is supposed to be possible to apply, say, left rudder and twist the sole of ones' foot onto the left brake pedal at the same time, but of course one overdoes it and so it is off with the left foot and on with the right, over control, change feet, over control again, change feet again etc. until one has the speed under control.

My corkscrew roll out was observed by the CFI of the local flying school, and his opinion that microlight pilots are cowboys - versed in the art of Square Dancing, was confirmed.

I finally got the beast under control and taxied back to the Aero Club, put it away - and had a beer !

My inexpert opinion is that a fixed skid may help you keep straight due to more friction - providing that you are determined to get on the rudders as soon as possible and prevent a groundloop from starting.

Try asking the Tiger Club - they used to be based at Redhill, not sure now, try Google - they have a fleet of Turbulents and I got good advice when I first purchased mine a few years ago and after I had experienced an engine failure on finals, eventually put down to flying the whole circuit with the throttle at idle, being used to 10,000 ft of hard runways I thought I was too high for the short grass runway I had selected, when I applied a bit of throttle to correct a slight downdraft the engine stopped - too cold !! If I close the choke after starting and apply throttle the engine stops, too cold, so had I grabbed a handful of choke I might have got a re-start, but I was too busy flying the aeroplane, successfully, no damage.

Best of luck, I'll be interested in your progress.

[mothminor]

Hi,
I have flown a currie wot with a fixed skid (no brakes) for the last 23 years.
Taxying on grass is fine up to about 15kts x-wind, a bit less in summer if the grass is baked and hard.
Landing on grass is ok up to 15kts (soft grass) down to about 10kts hard grass.


I try to avoid tarmac.
I cannot taxy on tarmac in any x-wind, if I have to operate out of a tarmac airfield I "walk" the aircraft to the hold, then take off into wind.


If I try to land on tarmac in even a 5kt x-wind, I know to expect to loose directional control at the end of the landing run.


I have flown a turbulent with a fixed skid on grass ( lovely aeroplane):) and have seen them fitted with a wire brush attached to the skid for operating on tarmac (good suggestion to ask the Tiger Club - I think they did this also).
Yes, I think a wire brush from Halfords (saw off handle), drill a hole in your "shoe" retain the brush with a 1/4" bolt.


Best stay away from brakes if you can. Keep it simple ;)
Best
J.J.

[creweite]

I used to bolt a wire welding brush on my Turbulent tailskid, provided braking action on a hard surface and good directional stability. From memory, I think Colin Rogers came up with this idea many years ago!!

[abgd]

Thanks all for the replies.

My Turbulent has the same rudder pedals as ExSpeedBird's - I find them quite good for engine run-ups and low-speed maneuvering, but utterly impractical when trying to use them with the rudder pedals at any speed. I've read a description of rudder pedals that apply brake as they approach their limits which sounds a more sensible option to me, except it's not then clear how you apply brakes to both wheels to run up the engine.

I think I read your report of carb-icing (I think it was your write-up) before flying and it has kept me rather paranoid about using carb-heat - thank-you. My engine stopped once already whilst taxiing in wet grass.

I'm pondering a welding-brush, but fear it might make me unpopular if it started shedding bristles given that turbines and heavyish aircraft sometimes use the runway.

MothMinor's observation that you have no directional control towards the end of the landing run pleases me... If that's what was to be expected, then I find that paradoxically reassuring.

[Capn Bug Smasher]

I've read a description of rudder pedals that apply brake as they approach their limits which sounds a more sensible option to me, except it's not then clear how you apply brakes to both wheels to run up the engine.


This is the case in a Rollason Condor. There is a handbrake which applies pressure to both wheels as well as differential braking with full pedal travel. Give me a few hours and I will try to find a diagram in the aircraft handbook for you.

[foxmoth]

I have flown various dH types off tarmac with a skid, whenever i do this I always wheel on and hold the tail off as long as possible, by then I am down to taxi speed, not sure how good the Turbulent is but think it would work ok. Another thing to watch for are high center taxi lines, i have taxied out ok only to have the skid catch on a high painted center line which then took me off the side!

[Maoraigh1]

Wire bristles can cause tyre punctures. Potentially very serious if tyre has deflated in flight, especially if aircraft has substantial spats.(wheel pants).

[abgd]

Hmm.... The wire brushes are a really interesting suggestion, and I admire the lateral thinking behind them, but I think I'll give them a miss in that case.

I'm not sure whether I entirely follow the reasoning behind keeping the tail up..? It keeps the mains further back which will reduce the tendency to ground-loop, and perhaps the tail in the airflow a bit better? Is part of the problem the sudden change in handling when the skid is on the ground?

[2hotwot]

The Rollason Turbullents had differential brakes on the end of the rudder travel. These seemed to provide a compromise for crosswind taxi with the stellite skid. The Turb is quite light on the tail so any brakes have to be used with caution!

[abgd]

Finally, I got the tailwheel set up and had another short flight yesterday.

I built the tailwheel as per plans - i.e. free-castering. At low speeds it was still quite a handful, but much more controllable than the skid. At high speeds it was quite well behaved. I haven't got even an intuitive grasp on how tailwheels 'work', but despite being free-castering it clearly gave you a lot more yaw stability than the skid.

I think I have the same brake pedals as ExSpeedBird and yesterday, rather than starting on the rudder pedals and then moving my feet to the brakes as I got slow enough to need them, I did so well in advance covering each rudder/brake combination with the respective foot - you reach full brake travel at the end of the rudder travel so can use both together. It's not an ergonomically pleasing system, but it is workable with practice and with brakes that are reasonably progressive.

The other slightly alarming observation was that at idle there's now enough thrust to start the aircraft moving gently forwards - with the skid this wasn't an issue, even on tarmac. On grass it's still OK, but methinks the chocks now need a piece of string so I can pull them both out at the same time from behind the wing.

[abgd]

The latest - and hopefully final - update on the tailskid saga.

My Turbulent has a curved tailspring which means that the end of it is in the right position but at the wrong (increased) angle relative to the ground. This means that with the first assembly the pivot of the tailwheel is canted somewhat forward (as you follow it down) - somewhat akin to the front forks of a bicycle.

https://c2.staticflickr.com/8/7418/28121726025_6269d77cf6_n.jpg (https://flic.kr/p/JR2cpg)

According to the plans, the tailwheel should sit with the pivot of the tailwheel canted only very slightly forward. With the aircraft loaded, it then points slightly backwards.

This meant that the tailwheel 'liked' to sit in front of the pivot, at least at low speed. At speed the original tailwheel assembly performed admirably, but on slow taxiing or trying to pull the aircraft out of the hangar, it was always conflicted between trailing and leading the pivot, making it hard to control.

Mk. II assembly is now adjusted to allow for the non-standard tailspring, with the geometry of the tailwheel assembly relative to the ground (angle of the pivot) now matching the plans. It works much more happily at low speed - at high speed they're about the same.

https://c2.staticflickr.com/8/7322/28043779521_5a348de368_n.jpg (https://flic.kr/p/JJ8GC2)

Monday saw 3.5 hours of happy flying - alas, on tarmac a tailwheel is clearly the way to go. The tailwheel changes the 3-point attitude quite a bit and there's clearly more drag than with a skid. I had one dodgy landing where I would doubtless have lost it, had I been using the tailskid. As things were, it was highly inelegant but came nowhere near a ground-loop. For one 2 hour flight I throttled back to 2000 rpm, about 70 kts indicated (I'm still uncertain about the accuracy of the ASI) then refilled the tank with just 14 litres.

Still getting used to the brakes. For landing I can cover the right brake pedal and the rudder together quite easily with the right foot, and I can cover the left rudder and brake pedals with the left foot. Differential braking for steering is quite easy. For run-ups I can use one foot on both pedals. But using both brakes to slow down is still beyond me!