What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Strong Crosswind, not a great outcome

........ I generally try to land diagonally on the runway - that buys a little margin. Paul

Ditto here. However, I did manage to do a mild ground loop with my wife aboard once.... Told her I was just trying to make a quick turn off. :D

Glad all is well Steve and we are all here learning a thing or three.

By the way, count me in the stick all the way back crowd. Good or bad, I also start bringing the flaps up on the roll out as quickly as I can.
 
Last edited:
If it isn't, how would you ever get the wheel to unlock when you want it to?

My 120 has a Scott 3200 which is a heavy duty tail wheel for the airframe. Takes a pretty good stab on a brake to get the tail wheel to swivel when taxiing.

The 120 has enough adverse yaw that full aileron deflection into the wind will result in a track to the downwind ditch if left unchecked with a minor crosswind. I have only flown an RV once but suspect that most of the adverse yaw has been eliminated thru aileron differential. Maybe someone with experience in the RV can comment on this.
 
My 120 has a Scott 3200 which is a heavy duty tail wheel for the airframe. Takes a pretty good stab on a brake to get the tail wheel to swivel when taxiing.

The 120 has enough adverse yaw that full aileron deflection into the wind will result in a track to the downwind ditch if left unchecked with a minor crosswind. I have only flown an RV once but suspect that most of the adverse yaw has been eliminated thru aileron differential. Maybe someone with experience in the RV can comment on this.

My only comment is that I didn't understand the comment regarding adverse yaw induced by the ailerons on a tail dragger RV having an effect on the landing characteristics.
Adverse yaw in flight is nearly nonexistent at higher speeds. There is some once you begin to get slow, but even then it is still minimal compared to a lot of airplanes. I guess at low speed and high AOA (three point attitude) it might have some influence but I have never noticed it.
 
Well, its confession time. After 400+ hrs in the RV-8, and over 500 hrs of total tailwheel time, I just groundlooped the RV-8. Fortunately nothing damaged but my ego and confidence. But...

Does this look familiar?

https://youtu.be/mK8_wfAFWEA

This video was taken on the dash cam of my RV-8 a year or two ago at Sulphur Springs Airport (KSLR). I can certainly identify with the feeling of helplessness when the aircraft CG moves outside the main gear and keeps going forward and sideways. Full rudder and brake didn't do a thing.

A couple of thoughts:

1. You may notice from the wind sock that I had a left quartering headwind. The AWOS said 17 knots, however the sock doesn't seem to be extended as much as I would have expected. You may not be able to tell, but there is a line of trees which parallels the runway on the left for the first 1200' or so, and that line of trees turns to the left and extends on a 45 deg. angle for a few more thousand feet. Google Earth clearly shows this. My guess is that this tree line blocked most of the crosswind until I lowered the tail on my wheel landing, when it effectively funneled the full force of the wind onto the runway at the point where things started going to pot.

2. You may hear some tire screeching during the first portion of the loop. That was the tail wheel, which was well scuffed. The mains were fine. I didn't have the stick full aft when I lowered the nose, which is a habit I have since worked on. BTW, it is a bit difficult to get full aft stick in and -8 with the aileron displaced, which compounds the problem.

3. You probably can't tell, but I lowered the tail early in the ground roll rather than waiting until it wouldn't stay up any longer. IMO, that contributed to the situation as you can see that the nose started to go left as soon as I lowered the nose. I don't do that anymore.

4. Finally, once I realized I no longer had control of the plane, I remembered an old Air Force instructors words: "Sometimes the plane knows how to fly when you don't". I just let off of the rudder and let it do what it wanted. It immediately stopped looping and straightened out, albeit 90 deg. to runway heading. Since the ground was wet I immediately added power once I was in the grass and under control again and was able to taxi back onto the runway with no damage other than mud inside my wheel pants and a scuffed tail wheel.

So here's my take: Keep the tail up as long as it will fly. Keep the stick full aft once the tail wheel is on the ground. Only land in a crosswind when no one is looking.

-John

P.S. Forget everything. A review of the video showed a black crow which flew just across my nose just before things started getting interesting. I have decided to blame the ominous crow instead of anything I did. ;-)
 
So here's my take: Keep the tail up as long as it will fly. Keep the stick full aft once the tail wheel is on the ground. Only land in a crosswind when no one is looking.

-John

P.S. Forget everything. A review of the video showed a black crow which flew just across my nose just before things started getting interesting. I have decided to blame the ominous crow instead of anything I did. ;-)

Very funny!

I'll add another: don't believe all the crosswind claims that you might read on the internet!
 
No consensus

Well after many posts. There seems no clear consensus on many of the points. I am going with:

Shorten horn to reduce unlocking tendency

Aileron into the wind

Hold tail off as long as possible

Center rudder as tail touches

Full aft stick (aileron still into wind)

Ready on brakes and power

Clench butt cheeks

Did I miss anything?
 
Hi Gary,

I recommend you don't center the rudder as the tail touches. The tailwheel angle as the tail touches will be working in your favor, helping to steer you away from the wind. Releasing rudder in a strong crosswind can set you up for loss of directional control.
Some practice at an airport that gives you a smooth 20k direct crosswind is great for tuning up technique in the 8.
 
Moving the rudder horn attach point inboard does two things; the tailwheel is less sensitive when on the ground, and it buys some additional margin before swivel release at full rudder deflection.

I'm not a big fan of chains, or the crappy little wire clips most folks use to attached them. It's too easy to build nicropressed cable assemblies.

Tailwheel%20Cable.jpg
 
Last edited:
This was the result of a bad crosswind landing in my plane. The poor tire gave its life to keep me on the runway...

PrqFon.jpg
 
Well after many posts. There seems no clear consensus on many of the points. I am going with:

...Hold tail off as long as possible

I don't know about the RV-8 but in other RVs you can hold the tail up so long with elevator that the rudder has very little authority by the time the tail quits flying with full forward stick. Does not seem advantageous in gusty/x-wind conditions. How is the RV-8, and what is the logic? Most tailwheel airplanes have a middle phase between 3-pt touchdown speed, and the speed at which the tail will no longer fly that is the sweet spot for lowering the tail under control.
 
Moving the rudder horn attach point inboard does two things; the tailwheel is less sensitive when on the ground, and it buys some additional margin before swivel release at full rudder deflection.

I'm not a big fan of chains, or the crappy little wire clips most folks use to attached them. It's too easy to build nicropressed cable assemblies.


Dan, I'm going to take your suggestion, and replace the chains with cable. I've had those 'crappy' clips come loose, but fortunately spotted it on preflight.


Roger Bloomfield
N51BL RV8 70 hours
 
Thanks for starting this thread Steve. It prompted me to take a closer look at my tailwheel, with a steering arm on the left side.

I discovered that full left rudder causes the tailwheel to unlock just before the rudder hits the stop. Right rudder is OK. I played around with the available adjustment in the length of the steering arm, but on my aircraft it is not possible to adjust it so it works like it should.

I see two possible ways to sort this out, while keeping the steering arm:

  1. Fabricate or purchase a new arm for that mounts on the tailwheel pivot. The new arm must be swept back, so a line between the tailwheel pivot and the end of the arm is parallel to a line between the rudder hinge and the front mounting hole for the steering arm.
  2. Purchase a longer rod end for the steering arm, and drill a new hole for the front end. The new hole would be further forward, making the angle between the new hole and the rudder hinge closer to parallel to a line between the tailwheel pivot and end of the aft arm.

Can anyone point to a tailwheel steering arm vendor who sells a pivot arm that is swept aft far enough so the angle between the tailwheel pivot and arm end is parallel to a line from the rudder hinge and the hole where the front end of the arm mounts on the rudder horn?

Alternatively, I could go back to two springs with chains or cables. I had moved away from the usual chains and springs as they were hitting the bottom of the rudder fairing.
 
Steering

I have used the stock chains, rocket link and the tail lynx over the past 14 years.

The stock chains work well and are inexpensive. The attach clips are the weak link and can be troublesome. They can be safety wired to keep from spreading, but seem to still magically come undone. The chains can be difficult to get the adjustment wanted. Either a little long or a little shorter than desired. Swagged cables and better attach hardware solves this. Heavy, draggy and ugly.

I personally do not like the rocket style single link. To responsive when having to jab rudder on landing. Uneven swivel disingagement do to the asymmetrical swing of the rudder horn attach point of the link. The rudder hinge pivot is forward of the horn attach point making no way to get true symmetrical left and right travel. Only thing I like are the looks and slot car taxi steering. Hate it for crosswinds and landings. Maybe the new ones are better, but the old ones were known to break and could go over center.

Have been using the tail lynx since offered by Van's. They are totally adjustable when first installed. Great looking. Great spring compression to allow adequate rudder movements without jerking the tailwheel steering when landing. Symmetrical steering and predictable steering release. High quality, light weight and again good looking. Only draw back is the the springs hit the rudder bottom with full rudder deflection. The designer does not recommend swapping ends to prevent this. Live with it, relieve the rudder bottom or install scuff tape. Not cheap, but good value.

Once had the steering pawl stick and not lock after landing. It was terrible taxiing to the ramp with a crosswind. I can not see how some can live with no steering. Just me?

George Meketa
Rv8, 1500+hours
 
Softer spring for rocket link?

I personally do not like the rocket style single link. To responsive when having to jab rudder on landing.

It seems a common observation that the rocket link spring is too stiff. Does anyone know if it is possible to install a softer spring, and has this been attempted in the past?

Tom.
 
444TX;1112713Swagged cables and better attach hardware solves this. Heavy said:
They are heavier, and certainly have more drag than a single link. However, there is beauty in form that perfectly follows function.

It seems a common observation that the rocket link spring is too stiff. Does anyone know if it is possible to install a softer spring, and has this been attempted in the past?Tom.

Remember, with a softer spring is tricky. For any given rudder deflection, increased spring travel allows the yoke to swivel further toward the unlock point. A softer spring and relocating the attach point on the rudder horn (or installing a longer arm on the yoke) might work.

Can anyone point to a tailwheel steering arm vendor who sells a pivot arm that is swept aft far enough so the angle between the tailwheel pivot and arm end is parallel to a line from the rudder hinge and the hole where the front end of the arm mounts on the rudder horn?

I'll bet you could talk Jason and Darwin into prototyping one. Their standard single arm has three link attach positions.

http://www.jdair.com/tailwheel-items/

Alternatively, I could go back to two springs with chains or cables. I had moved away from the usual chains and springs as they were hitting the bottom of the rudder fairing.

Insert an AN42B eyebolt from the underside of the rudder horn. Use washers to space the eye down some reasonable distance. See the photo above.
 
I discovered that full left rudder causes the tailwheel to unlock just before the rudder hits the stop. Right rudder is OK. I played around with the available adjustment in the length of the steering arm, but on my aircraft it is not possible to adjust it so it works like it should.

Kevin,

I checked this too and found the same thing. However it occurs to me that in its "pulling" mode (left rudder applied) the tailwheel link is doing precisely what a chain would do. The only real difference is spring travel (unless the chains are left loose). It therefore seems that tight chains could also be capable of unlocking the tailwheel with full left rudder applied (particularly in the air before the tailwheel touches the ground). Unlike the tailwheel link the chains could also unlock the tailwheel with full right rudder.

You idea of a back-swept tailwheel control arm is a good one for fixing the geometric asymmetry, but unless I'm missing something the only complete solution to the unlocking problem is slack chains? Either that, or modify the tailwheel bearing to increase the range through which the pawl remains engaged.
 
You idea of a back-swept tailwheel control arm is a good one for fixing the geometric asymmetry, but unless I'm missing something the only complete solution to the unlocking problem is slack chains?

Slack chains can create a type of unlock problem.

Thought exercise:

The tailwheel releases when the pin reaches the end of the slot in the yoke. It can get to that angle by (1) being pulled there by the rudder, or (2) being pushed there by side force on the tire contact patch.

Imagine a setup with no springs, just tight chains. We can adjust relative length of the rudder horn and tailwheel arm so full rudder deflection does not allow enough tailwheel angle for the lock pin to reach the end of the slot. With this system, the tailwheel could not unlock, even on the ground when using a towbar. It can't rotate far enough because the rudder is against its stop.

Now substitute loose chains. Although rudder deflection cannot rotate the fork far enough to reach the end of the pin slot, side force at the tire contact patch may get it that far because of the slack in the connecting member. The fork can rotate farther than the rudder can move it, beyond the limits of the rudder stop.

Soft springs have exactly the same effect as loose chains.

The perfect system does not allow the fork to reach the end of the pin slot with full rudder deflection, but has just enough spring travel to allow reaching the end of the pin slot when significant side force on the fork deflects the spring. How significant is a function of spring rate. There are only four ways to generate that side force; (1) a locked brake, (2) a towbar, (3) a runway surface defect that literally knocks the tailwheel sideways, or (4), you've already reached an unsalvagable groundloop angle.
 
Last edited:
Slack chains can create a type of unlock problem.

Thought exercise:

The tailwheel releases when the pin reaches the end of the slot in the yoke. It can get to that angle by (1) being pulled there by the rudder, or (2) being pushed there by side force on the tire contact patch.

Imagine a setup with no springs, just tight chains. We can adjust relative length of the rudder horn and tailwheel arm so full rudder deflection does not allow enough tailwheel angle for the lock pin to reach the end of the slot. With this system, the tailwheel could not unlock, even on the ground when using a towbar. It can't rotate far enough because the rudder is against its stop.

Dan,

Interesting point. However it would seem that the natural tendency of the tailwheel tire is to straighten itself out rather than to diverge sideways? This minimizes its rolling resistance. Probably the wheel could get knocked sideways though on a rough surface (grass or very bad pavement).
 
My Experience

I've got about 420 hours in my RV-8, and wish this thread was written back before I had all my tail-wheel problems! This is a complicated topic because there are a lot of variables: winds, landing surface, TW link slack, etc. Without boring you all with my stories, this is what I know:

1. It is possible to adjust the link slack so that full rudder deflection will unlock the TW (for tight turns on the ground) WITHOUT unlocking the TW in the opposite direction. If more slack is taken out the TW will then unlock in BOTH directions (which will allow the nose to weather-vane once you loose rudder authority on roll-out). This appears to be an intentional design decision. So just raise your TW, take off the nut, and set the slack you should use so that full-rudder deflection unlocks the TW in the direction of turn ONLY (it should still be locked in the other direction). This adjustment will, hopefully, minimize the chance your TW will unlock when full rudder deflection is being used to keep you on the runway during roll-out.

2. Next, when landing in strong crosswinds, don't keep the tail up. Get it down and apply full aft stick when below stall speed. This will help keep you away from full rudder deflection and the possibility of unlocking your TW.

3. Next, start a go around if you ever start to weather-vane. The prop wash on the rudder will make it immediately effective and you might even continue the landing if you've got it back under control.

4. Next, make sure that locking pin is always clean, smooth, and lubricated.

5. Finally, you could upgrade your brakes so that you have more stopping power when using differential braking to keep the tail behind you.

My history with this? I didn't like much slack in the TW link so I took it out. Eventually ground looped on Catalina Island when TW became unlocked. Was forced off 2 runways without looping when I liked to hold the tail up until loosing rudder authority. Last week I finally tested the cam action on the TW and discovered I HAD to loosen the links because full rudder deflection was unlocking the TW in both directions.

Live (hopefully) and learn (I guess). Again, this is a great thread!
 
Thanks for starting this thread Steve. It prompted me to take a closer look at my tailwheel, with a steering arm on the left side.

I discovered that full left rudder causes the tailwheel to unlock just before the rudder hits the stop. Right rudder is OK. I played around with the available adjustment in the length of the steering arm, but on my aircraft it is not possible to adjust it so it works like it should.

I see two possible ways to sort this out, while keeping the steering arm:

  1. Fabricate or purchase a new arm for that mounts on the tailwheel pivot. The new arm must be swept back, so a line between the tailwheel pivot and the end of the arm is parallel to a line between the rudder hinge and the front mounting hole for the steering arm.
  2. Purchase a longer rod end for the steering arm, and drill a new hole for the front end. The new hole would be further forward, making the angle between the new hole and the rudder hinge closer to parallel to a line between the tailwheel pivot and end of the aft arm.

Can anyone point to a tailwheel steering arm vendor who sells a pivot arm that is swept aft far enough so the angle between the tailwheel pivot and arm end is parallel to a line from the rudder hinge and the hole where the front end of the arm mounts on the rudder horn?

Alternatively, I could go back to two springs with chains or cables. I had moved away from the usual chains and springs as they were hitting the bottom of the rudder fairing.

I have asked Darwin to make a swept steering arm. I went so far as to design the perfect sweep angle and length for him so that the steering angle is symmetrical left and right and very slightly less than the current version. He replied that he would talk to his fabricator about making a prototype for me to try out. That was a month or two ago, no word since.

He keeps saying they don't hear of any problems.....
 
A third factor that I will check today is that with full rudder deflection, and pushing pretty hard on it, I wonder if the pedal might touch the firewall with less than full braking. I'm sure I would have checked that when I built it, but maybe not including the flexing of the system under hard pushing.

Steve, I have a friend that ground looped his RV-8 some time ago that he did not build. The outcome was similar to yours without damage, other than his confidence for a short time. He kept saying he felt like there wasn't enough braking authority and upon inspection of the pedals, there were indeed hitting the firewall and only providing approximately 75% of braking. I've spoke to a few other RV-8 owners that have said that early on in their testing they noticed similar issues with their own builds. This could be a big possibility with your situation.

Glad things turned out okay for you.
 
This is what I teach. Power makes the rudder bigger. Your flying until it's tied down...
Glad there was no damage.

In my -8 I've learned to be ready on the throttle during roll-out. If a sudden gust hits and you suddenly find yourself out of rudder and opposite brake, a quick stab of throttle will give you a lot of rudder authority and straighten things right out. The one time I really needed this, it worked like a charm (in 580 RV-8 hours).

Skylor
 
Tail Wheel

If you fly tailwheel long enough your in one of the two categories.
1. Those that have ground looped.
2. Those that are going to ground loop.

Like my old buddy that flew Jenny's with OX5 engines.
He said it was not if the engine was going to quit it was when its going to quit.
Bob
 
Which rudder pedal are you pushing when you take with no wind?

This is what I teach. Power makes the rudder bigger. Your flying until it's tied down...
Glad there was no damage.

If you have that pedal all in as speed is decaying on roll out then you add a bunch of power what is happening? This is when you need to think about which wing you want to be up wind. Same for take off.
Cm
 
definitive solution to the unlocking-fullswivel-tailwheel-in-a-crosswind problem

The original Van's tailwheel design for -3's and -4's was a direct-chain-with-springs-to-tailwheel-fork that would not full-swivel (hope this pic gets included ok):

2mzz6f9.jpg


When you want to push the plane backwards, just go slow so it won't wrap around and jam - you could steer the thing 30-40 degrees left or right. Otherwise, see the long bolt through the axel? That's meant to take a nosewheel tow-bar, which just hooks on and you drag it backwards into the hanger.

(oh, and yeah, that funny looking weldment raises the assembly a few inches so the vertical axel won't bash the pavement)

3200 takeoff/landings on this, nowhere near a groundloop. Why the full-swivel design was introduced, exposing everyone to the unlocking-tail-wheel-in-a-bad-crosswind problem (but making it more "convenient" to push the plane backwards) is a mystery to some of us old-timer RV'ers.

But ... to each his or her own.

cheers!

- SJ
1100 RV3 hours
(three more last week!)
 
I'd never tell anyone to do as I do, but if you use the old style without the chains & springs, you'll always be ready with the brakes. :) Eliminates the issues with backing the plane, too.

The only time I've ever involuntarily departed a runway, was after an A&P 'repaired' a Luscombe tailwheel that wouldn't lock. He got it locking in one direction but not the other, & I left the runway going the direction that it *did* lock. Never had any problems when it wouldn't lock; just used rudder & brakes to control the plane. Later flew a Swift for about 190 hrs without chains, and I've got hundreds of hours in a couple of -4s without chains.

To those that say to stay off the brakes: brake pads are much cheaper than aluminum.

Charlie
 
My story and ideally a Cable or an Electronic Solenoid

I went through the whole runway excursion thing a couple of years back with a cross wind gusting of 25 plus knots at 60 deg off the runway on the left side. I could keep the plane lined up barley with the wing low method until the tail came down. At that point it was heading off the runway faster then anything I?ve ever experienced. The strip being 50 ft wide, in the mountains, landing up hill also didn?t help. With the skid marks from the tire being scrubbed across the runway I honestly thought I was going to flip and drag a wing tip. I was fortunate that there was no damage to my RV4, only to my pride. My girl friend thought it was all part of the ride until the F bomb came out of my mouth.

I went back to the hanger to reflect on what happened, took the tail wheel apart and played with it. I understood at that point that with Full Rudder Deflection (as used in a severe X-wind landing) the tail wheel will unlock until you straighten it up enough to lock again and in the conditions I had, that was impossible to do. (Vans design with the springs)

I?ve also replaced all of the parts for new, tried grinding the slot in the arm a little deeper but its still the same and is part of the design.

Ideally the best of both worlds would be one that a guy could un-lock the Pin via either a cable or an electronic solenoid. That way its always locked and you can unlock it only when you need it.

Tim
 
Quick caution - If you're trying to get it under control and it's skidding a tire, be careful coming up with power, especially if you're using brake, too. In some planes that can lead to a nose-over.

Dave
 
Steve don't beat yourself up. It is easy for the peanut gallery to Monday morning quarterback but we weren't there. It .

those who have and those who will etc. I guess you have moved now into the first group. Your entry fee was much lower than some others.
 
Back
Top