Skidding

[AGLyme]

Go pro attachment point... did you see Kent’s famous CTSW/ NYCity photo? 
 

[Skunkworks85]

13 hours ago, Dennis Yeo said:

   I have the drawing from Germany and it appears the gear should be lined up worth the center line of the airplane.    I trimmed off the front of the nose pant and it made a very big difference.  But still doesn’t fly as nice as with out the pant.   I really appreciate all of your feed back.  

 

I will pull the cowl off and re laser it. 

Where did you get this drawing? I would like a copy

[KentWien]

The previous owner did that I guess to make it more visible for people to avoid walking into it. 

[GrassStripFlyBoy]

Have been following this thread, certainly have noticed the nose wheel / skidding quirks of the CTsw, but reserved commenting until I was back up to do some maneuvering.  First, I have small non-tundra gear in 2006 CTsw.  I don't have issues with aircraft tracking straight, but does require the typical coordination with power changes, coordinated controls for turning, etc, which is nothing out of ordinary in flight.  Today in straight and level normal cruise I stabbed the right rudder pedal with a fairly hard push, released as quick as I input force, and the ball returned to about 1/4 ball off center staying towards the right.  Same input for left and the pedal did not return to center, rudder & ball stayed left a significant amount, and plane remained in firm left skid.  I assume this is has everything to do with prop wash force relative to front pant?  Anyone else notice the left input differs than right, curious if that is design condition or a unique situation I might want to investigate further.

[MEH]

On 12/5/2019 at 9:51 PM, Dennis Yeo said:

   I have the drawing from Germany and it appears the gear should be lined up worth the center line of the airplane.    I trimmed off the front of the nose pant and it made a very big difference.  But still doesn’t fly as nice as with out the pant.   I really appreciate all of your feed back.  

 

I will pull the cowl off and re laser it. 

Note the drawing has the centerline of the engine displaced down and to one side.  Given the left turning tendencies, it only makes sense that it is directed to the right.

[Dennis Yeo]

9 hours ago, GrassStripFlyBoy said:

Have been following this thread, certainly have noticed the nose wheel / skidding quirks of the CTsw, but reserved commenting until I was back up to do some maneuvering.  First, I have small non-tundra gear in 2006 CTsw.  I don't have issues with aircraft tracking straight, but does require the typical coordination with power changes, coordinated controls for turning, etc, which is nothing out of ordinary in flight.  Today in straight and level normal cruise I stabbed the right rudder pedal with a fairly hard push, released as quick as I input force, and the ball returned to about 1/4 ball off center staying towards the right.  Same input for left and the pedal did not return to center, rudder & ball stayed left a significant amount, and plane remained in firm left skid.  I assume this is has everything to do with prop wash force relative to front pant?  Anyone else notice the left input differs than right, curious if that is design condition or a unique situation I might want to investigate further.

With my original tundra wheel pant it did the same but would continued the left yaw until I would chicken out and Correct with right rudder.    I cut and reglasseed the front of the wheel pant and it now behaves like what you are describing.    No wheel pant was much better.   I am going to adjust the wheel connecting rods to see if that will help before I cut down and reglass the rear of the wheel pant.  Can you take a side picture of you front wheel pant for me.   Thanks. 

[GrassStripFlyBoy]

Pic of standard CTsw fairing below, also for discussion sake ever notice how a Cherokee has a fin integrated to rear, and how much area is rear relative to front of center on this and Cessna, not just length but vertical profile as well.  Spit balling by eye, I'd say these other have 2X ratio rear to front, the CT is appears more like 1:1 area wise.  I wonder if the Cherokee "fin" was an afterthought due to similar situation.  I might mock up something similar to the fin from aluminum (thoughtful 3D geometry with substance, not simply hack a flat sheet), have some wind tunnel high speed tape and ability to do this, and see how extra area to rear impacts centering.  I'd not go to re-glass step until confident the direction produces a good outcome.  I don't think cutting down rear is the direction to go, adding at rear to assist with weathervane is how I'm seeing the solution.

[Warmi]

Here is how it is configured for my Sting ....

 

[AGLyme]

Warmi, I like that mat material.

[Warmi]

We had quite a few leftover tiles from doing our garage at home so I figured why not use them in my hangar.

https://www.weathertech.com/techfloor/

 

 

[Anticept]

What MEH posted is correct, the reason for the skidding tendancies is that you trim the airplane for level flight, counteracting the propeller slipstream for one.

When you reduce power, it upsets the balance that you are trimmed for, and that's why it suddenly likes to fly in a skid.

[andyb]

9 hours ago, Anticept said:

What MEH posted is correct, the reason for the skidding tendancies is that you trim the airplane for level flight, counteracting the propeller slipstream for one.

When you reduce power, it upsets the balance that you are trimmed for, and that's why it suddenly likes to fly in a skid.

I would think that if retarding the throttle caused a right-turning tendency (mine does this too), then absence rudder correction, on a right pattern it would cause a skidding tendency, and on a left pattern it would cause a slipping tendency.

Is that correct?

Andy

[Dennis Yeo]

40 minutes ago, andyb said:

I would think that if retarding the throttle caused a right-turning tendency (mine does this too), then absence rudder correction, on a right pattern it would cause a skidding tendency, and on a left pattern it would cause a slipping tendency.

Is that correct?

Andy

I think it depends where you are trimmed  is to start with.  If you are over trimmed right to correct something then that makes a difference. 

[Skunkworks85]

On 12/6/2019 at 9:05 AM, FlyingMonkey said:

I guess I was wrong about the gear being slightly offset.  Age and senility are terrible things!

FlyingMonkey, Can you check your PM's?

[Anticept]

3 hours ago, andyb said:

I would think that if retarding the throttle caused a right-turning tendency (mine does this too), then absence rudder correction, on a right pattern it would cause a skidding tendency, and on a left pattern it would cause a slipping tendency.

Is that correct?

Andy

The prop slipstream hits the left side of the vertical stab, as well as the underside of the left wing and topside of the right wing, though those are more or less balanced out by torque.

This sets up a tendency for the nose to want to yaw to the left. So you trim the airplane so that the rudder is deflecting slightly right in straight and level to counter that left tendency.

For simplicity, if you remove power, you remove the slipstream effect. Now you have a trimmed rudder counteracting a nonexistent slipstream, and so the trimmed rudder will oversteer and push the nose to the right. In addition, as you are not approaching the oncoming wind straight on, the right wing is now partially blanked by the fuselage and so the inboard side of the right wing will generate reduced lift. Your right wing will now drop a little.

If you are in flight with a neutral trim and you remove power, then the airplane will just nose down some to compensate for loss of power.

I do not know how a CT would try to behave in a turn with neutral trim and no rudder. Some airplanes slip, some skid. Most tend to follow the nose (which in a turn, will want to follow the sideways gravity on it and slide deeper into the turn) so CTs will probably slip.

The left or right pattern does not matter in a neutral trim CT. CTs do not have any nonsymmetrical construction* except for the prop thrust angle, and that doesn't matter if there is no power (roughly speaking).

* Yes some aircraft have asymetry. Piper warriors for example have a slightly offset vertical stabilizer which is calibrated for straight and level flight, mainly because a lot of them don't have rudder trim. A lot of airplanes are like that.

[Ed Cesnalis]

8 hours ago, andyb said:

I would think that if retarding the throttle caused a right-turning tendency (mine does this too), then absence rudder correction, on a right pattern it would cause a skidding tendency, and on a left pattern it would cause a slipping tendency.

Is that correct?

Andy

slipping is too much bank for the radius and skidding is too little bank.  I think we are talking about skidding here either left or right not skid vs slip.

[Dennis Yeo]

Little off subject. Anyone know what this ball thing is for 

[cdarza]

OMG you found the golden egg !!!!        LOL kidding aside - seriously, what is that ???     Should have a contest for best answers;  Fuel Warmer for added horsepower ?     

[BravoFoxtrot]

It is the fuel system pressure accumulator. It dampens out the pressure fluctuations coming from your fuel pump so that your pressure gauge reads a steady value.

[Anticept]

And probably not needed anymore with the new fuel pumps.

Funny enough, those accumulators are on the *intake* side of the fuel pump.

I cannot remember if CTSWs used the fuel return restrictor. I know some aircraft models out there did not and it creates issues.

[Tom Baker]

41 minutes ago, Anticept said:

And probably not needed anymore with the new fuel pumps.

Funny enough, those accumulators are on the *intake* side of the fuel pump.

I cannot remember if CTSWs used the fuel return restrictor. I know some aircraft models out there did not and it creates issues.

All of the CTSW's I have seen had the restriction jet in the return line. I think the accumulator maybe was dual purpose. It allowed them to splice the inlet line to the fuel pump to the gascolator. The engines were delivered with a fuel line that was to short to reach the gascolator, and it also had a metric flared fitting on the end.

[Anticept]

I should also remind everyone: male sure the entire aileron and flap control system is being properly lubricated.

CTs have interlinked flaps and ailerons. They're flapperons in many ways. Poorly lubricated ailerons will have an effect on the flaps, though it probably isn't terribly significant.