Re: Ground Control


David J. Gall
 

Sorry, Peter,

Even if "proper procedure" were followed and the tailwheel alighted first, it occurs to me that the tailwheel deflection still would have been excessive for the amount of directional authority needed to overcome the crosswind. Whereas the (full) rudder deflection was apparently sufficient to align the airplane longitudinal axis with the runway centerline at or immediately prior to tailwheel touchdown, the concomitant tailwheel deflection at the same rudder pedal displacement was incorrect, ergo, the airplane has a _design deficiency_ that PUT the pilot in the position of having too much tailwheel deflection applied at the moment of tailwheel contact with the ground, irrespective of the contact or absence thereof of the main wheels with the pavement.

Thus, the gearing between the rudder and tailwheel is incorrect in that the same rudder pedal deflection results in differing amounts of control authority between rudder and tailwheel, whereas the correct ratio would yield differing amounts of _deflection_ to give approximately equal amounts of control authority. Engineering texts are available that clearly show the increment of coefficient of normal force ("lift") with rudder deflection to be on the order of about .05 per degree depending on the ratio of rudder chord to stabilizer chord, while pneumatic tires generally return about 4 to 5 times that rate. Gearing the two is only sensible. The absence of springs in the tailwheel control circuit to permit some relative movement and time for the pilot to readjust the pedal position at the moment of tailwheel contact is a contributing factor. The absence of the full-swivelling break-away feature may also be a contributing factor.

Other taildraggers have done it that way almost since the advent of the paved runway. You have probably had the benefit of such gearing and springs with most of your non-Q2 taildragger time. Why do you continue to insist that it is pilot error? Are you married to the idea that some superior wisdom went into the Q2 design decision to part with accepted practice?

Submitted for your considered review,


David J. Gall

----- Original Message -----
From: "Peter Harris" <peterjfharris@...>
To: Q-LIST@...
Subject: Re: [Q-LIST] Ground Control
Date: Wed, 24 Nov 2004 02:35:34 +1000



James/David,
The POH recommends land full stall tailwheel first.It is more common to land 3 point. It is unsafe to wheel it on, read sidegust with limited rudder authority,and how do you control tailwheel contact without bouncing it ?. By making tailwheel authority from the start of the ground run you have complete control, just watch the end of the runway and dance the dance.In your example missuse of the reflexor was followed by unsafe landing technique, especially in the strong crosswind .It bites.
Peter
----- Original Message -----
From: James Postma
To: Q-LIST@...
Sent: Friday, November 26, 2004 5:00 AM
Subject: Re: [Q-LIST] Ground Control


The pilot did not have time to react. I saw the whole thing. When the tail
came down, it went around like a top. This all happened on the runway. It
did a beautiful spin. So the POH recommendation to ground loop for
emergency stop works.

James Postma
Q2 Revmaster N145EX
Q200 N8427
Steilacoom, Washington
(253) 584-1182 9:00 to 8:00 PDT
May your header tank be always full and your wings right side up.

----- Original Message -----
From: "Peter Harris" <peterjfharris@...>
To: <Q-LIST@...>
Sent: Monday, November 22, 2004 5:43 PM
Subject: Re: [Q-LIST] Ground Control


>
> James if he had the rudder full over and held it that way when the
tailwheel touched down then sure it groundlooped. Surely the problem here
was caused in the first place by missuse of the everloving reflexer and then
by a second pilot error in the use of the pedals.
> Peter
> ----- Original Message -----
> From: James Postma
> To: Q-LIST@...
> Sent: Thursday, November 25, 2004 3:55 PM
> Subject: Re: [Q-LIST] Ground Control
>
>
> I repeat. The standard rudder is ineffective on the ground. Do not
count
> on it to do anything if your tailspring breaks. No theory here. Just
many
> results.
>
> My first introduction to this phenomena was my test pilot before I flew.
He
> had the reflexor down and could not get the tail on the ground. He had
the
> rudder full over because of a small crosswind. When the tail came down,
> there was an immediate ground loop. There are two other results on this
> list in the last two months. Please read them.
>
> James Postma
> Q2 Revmaster N145EX
> Q200 N8427
> Steilacoom, Washington
> (253) 584-1182 9:00 to 8:00 PDT
> May your header tank be always full and your wings right side up.
>
> ----- Original Message -----
> From: <britmcman@...>
> To: <Q-LIST@...>
> Sent: Wednesday, November 24, 2004 5:18 PM
> Subject: Re: [Q-LIST] Ground Control
>
>
> >
> >
> > In a message dated 11/24/04 10:06:21 A.M. Pacific Standard Time,
> > james@... writes:
> >
> > A bell crank with separate wires for the tailwheel and rudder is part
of
> the
> > JB 6 pack. This enables the use of springs for the tailwheel to
soften
> it's
> > effect. It also enables control of the rudder should the tailspring
> break.
> > This will not be very effective with the standard rudder
> >
> >
> > Say again Jim P.?
> >
> > JB 6 Pack very effective with the STANDARD RUDDER.
> >
> > Phil Lankford
> > N870BM

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