Bend Tri-gear fork

[bakfly]

Hi all,

A number of month ago I noticed my nose-wheel Tyre starts rubbing agains the the Tri-gear fork on my Sonex. The fork had bend to the right. I noticed already for a while that I needed a lot of left rudder input during taxing and before take off. I took the Tri-Gear strut off and bended using a press straight again. After a number of month and probably about 20 landing and take off, I notice it started to bend to the right again. I am using most of the time the main bitumen runway what can have a bit of crosswind. I was thinking to reinforce the fork, but Sonex advice me: this will allow the loads that caused this damage to be transferred to other parts, such as the motormount, that are far more expensive to replace should they become damaged. I have now ordered a new Nose-Gear Strut and Nose-Gear Strut Drive Horn. I noticed when the nose-wheel is aligned straight with the Fuselage the Rudder is slightly off to the right. I am not sure if this will cause any extra strain on the Nose-Wheel.

Does anybody have had the same problem and after replacing the Nose-Gear Strut not have this problem returning anymore.

Peter Bakker,
Sonex 1430, Tri-Gear, Aerovee 2.1
Flown 150hrs

[jjbardell]

I am on my third strut, it is very frustrating. Here are my thoughts.
1) Once it is bent, it is more likely to bend again if you press straighten it. It will always be weaker.
2) If you have a strut fairing on the front, I have found that causes aerodynamic flutter and bends the strut on the roll before take-off or just after landing so I removed mine. I did not notice a change in speed. The main gear strut fairings do make about 5-7mph
3) Make sure you are checking your rudder alignment with an angle measurement, not visual
4) Set and lock the rudder before you drill your new holes on the new strut

I believe bending is caused by the following:
1) Moderate / High speed exists from the runway
2) Not having the rudder and wheel perfectly straight before beginning the takeoff roll
3) At my airport, we have a displaced threshold which is bumpy. The bump between that and the runway start causes the strut to flex. I don't roll on the throttle until I am after the bump.

It is frustrating and I feel your pain. Not sure if any of this helps, but it has helped me. Since then, I have not had any issues.

[bakfly]

Thanks jjbardell for your useful reply.

Before drilling the holes in the new strut I will make sure the rudder is straight and aligned. Also I will concentrate during the beginning of the take off roll to have the Rudder and wheel straight.

During the take off, not using any Flaps I always put a little bit of back pressure on the stick. I am airborne at about 50 knots and accelerate in ground effect to 70 knots before start the climb. Maybe with the Sonex low stall speed, I can get airborne at 45 knots when using 10 degrees Flap.
I found that during the landing roll while moving the stick gradually fully backwards,trying to keep the nose wheel off the runway as long as possible it drops into the runway fairly quickly.
Especially when I fly on my own and having a full tank of fuel there is quite a bit of weight on the nose wheel.(Minimum pilot weight with full tank is 70kg to stay within envelop).

My Airport has several runways and most times there is always a runway straight into the wind. But only the main bitumen runway is good, the other grass runway are fairly rough.

Thank you for your help and I hope that this all resolve this problem.

Regards Peter