I was glad I was flying North yesterday...

[gismo]

My return trip from San Antonio went pretty well even though I had to take a significant detour around some fairly ugly weather over eastern KS and western MO. My planned and filed route would have taken us directly into an area that prompted some tornado watches along with some long lines of big TRW so from my fuel stop near Oklahoma City I headed northeast across northern OK and southwest MO to circumvent the worst. The choices were to fly up the middle looking for gaps, shoot further west and go behind the front or angle to the east and stay on the warm side of the front but far enough away to avoid the frontal storms. A look at the current NEXRAD convinced me that straight through would be iffy and going behind the front meant big (30-50 Kt) headwinds along with lots of wintery precip including a good chance for freezing rain and ice so up the eastern side it was. I've often wondered whether you could actually shorten the ETE by following the circulation around a low pressure rather than crossing it (assuming no violent stuff in the way) and I think this flight proved the concept. I had an average 40 Kt tailwind for most of the way with an 80 Kt push at one point (260 Kt GS). All this was fairly low (7000-9000) and relative to the first leg pretty smooth as well. The second leg came out to a bit less than 3 hrs which was the predicted ETE for the direct route where the winds were less favorable but still a decent tailwind so it seems the extra length (653 vs 588 nm) was fully compensated by the more favorable wind.

On the first leg from an airpark near San Antonio to Sundance near Oklahoma City, there was a tailwind, but the turbulence was awful at every altitude I tried. And from what I heard on the radio, it was rather bumpy deep into the flight levels. And the winds were bad at Sundance where they only have one runway that runs N-S. The ATIS at nearby KOKC reported winds gusting to around 50 Kt out of the SW and I needed all the crosswind tricks I had to get on and stay on the runway including a significant amount of differential thrust and yaw axis momentum. The worst part though, was fueling at the self serve which had an unusual overhead fuel hose setup. First I had to set the parking brake so the plane wouldn't get blown across the level ramp and then I had to wrap the hose around my torso to keep it from whipping into the plane. The plane was rocking in the wind so much that I had trouble getting the tanks full ad the rocking sloshed the fuel enough that it kept getting blown out of the filler when each tank got close to full.

I sure wished I had onboard NEXRAD. A call to Flightwatch got me a suggestion to head more east than north than my present course to Columbia MO, but when I requested that from Kansas City Center the controller said that looked worse to him so I just stayed near that course while deviating a little around some small cells in my path. Then he told me it looked like I could make the turn north earlier than COU and still avoid the bad weather which worked out as suggested. Gotta get going on that panel upgrade soon.

Coming across Iowa I learned that the weather in the Minneapolis area was considerably worse than forecast (400 ft ceiling/2 mile visibility vs the forecast 2000 ft/ 6PSM) and the flight ended with an ILS to about 300 AGL, one of the lowest I've done for real in a while.

The neatest part of the trip was landing and taxiing right up to my sister's house. She and her husband just built a new house complete with large hangar on a private airport community. Their hangar had room for my plane as well as the Stinson they own so the Baron spent the long weekend inside and out of the weather as well. I also got to have lunch with Bill Suffa where we talked about using a personal airplane for business travel, something my brother in law is interested in doing now that he's working for someone who allows that.

 

[Bill]

I needed all the crosswind tricks I had to get on and stay on the runway including a significant amount of differential thrust and yaw axis momentum.

Wow, I home someday to have some of the skills some of you experienced guy have...x-winds still sometimes kick my butt.

 

[gismo]

Wow, I home someday to have some of the skills some of you experienced guy have...x-winds still sometimes kick my butt.

Fortunately it was a wide runway so there was room for some error.

 

[jesse]

Hmm sounds like an adventure.

I flew to FCM saturday night to go to the mall of america and then flew back. looks like I barely cleared the approaching IFR. When I left RST ceilings were at least 20k or so.

On the way back they were down to 2200 AGL.

 

[Dave Krall CFII]

Can you amplify your XWind LDG technique for those of us that don't fly twins much ? Were you running out of rudder or does the thrust differential have other advantages ? What was the XWind component ?

 

[Dave Siciliano]

Wow Lance! Wish I could have lent you the 396; you could have overnighted it back!!

Now, I feel I'm flyin blind without one. Have found myself in your exact position before, one guy telling me go east; another saying it's better west and you have to pick an opinion.

The winds here in Dallas got up in the 60 mph range; knocked over a table on my patio and broke it!

I flew in Saturday evening and watched the NEXRAD on the 396 the entire way. Wound up flying right in between two systems--it worked out great!!

Glad your'e back home and got to visit with Bill!!

Sounds like you did a great job of circumventin those systems!!

(Oh, I won't say anything about how much easier it is to land a Baron in a strong cross wind than what some of these other guys on the Board are flying--I promise!! )

Best,

Dave

 

[wsuffa]

Lance,

Wondered if you made it back or got stopped by that ugliness in Kansas. Glad you got through.

Nexrad in the plane is something I'm really, really glad to have on long trips.

BTW, I've done the circumnavigate thing a few times with excellent results. Managed to fly south one day to pick up the counter-circulation around a tropical low - gave me significant tailwinds going west.

Great to see you when you were here.

bill

 

[Richard]

I was waiting for your report of the return trip. I forsure thought you'd be eating crow since bragging about your outbound leg to the south. Sometimes luck is a lady. "Pressure flying' does indeed work. Even if the results are marginal (ex, longer diversion, shorter trip, mild winds) for any particular trip it is well worth the experiment and usually results in some level of insight.

 

[etsisk]

Fortunately it was a wide runway so there was room for some error.

ain't a runway in the country wide enough . . .

 

[gismo]

Can you amplify your XWind LDG technique for those of us that don't fly twins much ? Were you running out of rudder or does the thrust differential have other advantages ? What was the XWind component ?

If you average the steady wind (36) and the gust (48) it comes to 42 Kt. The wind was from 240 and the runway heading is 170 for a difference of 70, giving an average crosswind component of 40 Kt (sin(70)*42=40).

The technique for best crosswind handling IME is to crab deep into the flare and then rapidly roll into the wind while applying enough rudder to point the airplane slightly away from the wind just before touching down. In a twin it's relatively easy to control the touchdown point since closing the throttles completely decreases the lift of the wings significantly. Since the plane's inertia delays the lateral movement this gets you on the runway with near zero drift in conditions that preclude holding a steady slip to stay aligned. But as you slow down the plane will want to weathervane into the wind and bringing up the throttle in the upwind engine (only) both increases the effectiveness of the rudder and assists holding the plane's heading by generating a big yaw force. You have to maintain the asymmetrical thrust until you are going slow enough that the nosewheel has enough grip to do the job, or failing that, until you pull off the runway and align the plane with the wind.

 

[Let'sgoflying!]

I would be interested in hearing the aerodynamics of using differential thrust on final to maintain longitudinal alignment in a crosswind if anyone has any experience with it.
I have heard plenty of 'dont'....but little 'why not'. (I can guess at a few reasons but was looking for some good explanations)

 

[gismo]

I would be interested in hearing the aerodynamics of using differential thrust on final to maintain longitudinal alignment in a crosswind if anyone has any experience with it.
I have heard plenty of 'dont'....but little 'why not'. (I can guess at a few reasons but was looking for some good explanations)

I can only think of a few "why nots". One is that with differential thrust, the plane will change heading with every power adjustment, and in heavy gusty wind, I tend to change power a lot (maybe too much) to control the rate of descent. The other is that a stall, even a brief one with significant asymmetrical thrust can be hair raising, especially if one engine is near idle. Granted I would normally maintain a high enough airspeed to aviod stalling in the first place, but why add risk that way. Finally, the higher power engine will be on the higher wing (you still need to compensate for drift) and that puts you in a precarious place if the other one choses that moment to quit. And since the fuel pickups are generally located on the inside end of the wing tanks, that low engine is the one which is most likely to start sucking air. For that reason plus passenger discomfort, I prefer to fly my approaches coordinated (in a crab) and rotate the longitudinal axis into alignment with the runway just before touchdown.

That said, at slightly above VMC, maximum differential thrust (one engine at full power the other idling) should have more yaw authority than the rudder. A little faster at Vyse, I'd expect the rudder to be stronger even with the bank into the low power engine (banking that way increases VMC), but either way you should be able to generate nearly twice the static yaw force with both rudder and differential thrust. That doesn't mean twice the yaw angle as the airplane's response to yaw force is rather non-linear with diminishing returns beyond about 15-20 degrees.

 

[Dave Siciliano]

But as you slow down the plane will want to weathervane into the wind and bringing up the throttle in the upwind engine (only) both increases the effectiveness of the rudder and assists holding the plane's heading by generating a big yaw force. You have to maintain the asymmetrical thrust until you are going slow enough that the nosewheel has enough grip to do the job, or failing that, until you pull off the runway and align the plane with the wind.

Help me out here a little sin/cosin guy!! Let say the winds are 90 degrees off your right wing. I would normally have the nose pointed way into the wind until just before touch down; or, use strong enough cross controls to have the right wings way low until just before touch down. In the first case, just above the touchdown point, I'd let go of the right rudder so the nose came around as I was getting the mains on the runway (usually, the right main would touch first). Which engine are you saying to add power to? Adding power to the left would push the nose right; are you saying add it to the right to get better rudder control? What do you mean -- upwind engine?

I'm a little confused.

Dave

 

[jesse]

Help me out here a little sin/cosin guy!! Let say the winds are 90 degrees off your right wing. I would normally have the nose pointed way into the wind until just before touch down; or, use strong enough cross controls to have the right wings way low until just before touch down. In the first case, just above the touchdown point, I'd let go of the right rudder so the nose came around as I was getting the mains on the runway (usually, the right main would touch first). Which engine are you saying to add power to? Adding power to the left would push the nose right; are you saying add it to the right to get better rudder control? What do you mean -- upwind engine?

I'm a little confused.

Dave

I think he means (I like to draw things out..understand it a lot better then..plus i'm bored at work)

 

[gismo]

I think he means (I like to draw things out..understand it a lot better then..plus i'm bored at work)

Jesse's got it right. I used differential thrust to prevent the plane from weathervaning to the right (crosswind from the right) after I touched down. I had both engines producing the same power during the approach and touchdown. I think that if you were to use engine thrust to maintain a "forward" slip on the approach (a bad idea IMO) then you'd still need increased power in the right (upwind) engine along with left rudder and right aileron. I think you'll find this is fairly intuitive in the airplane, much like using differntial thrust to turn the airplane while taxiing. Thinking about it just confuses me sometimes.

 

[Dave Siciliano]

Oh! I see now. I'm used to using the downwind engine to push me into the wind a little. Looks like he's saying if one didn't have enough rudder, the upwind engine could provide it!! Hummm!!

Normally I use cross controls until the last minute; get the upwind main to touch, then get the nose around the last little bit before the other main touches. This will be a fun discussion in Madison!!

We can practice in Lance's plane!!

Dave

 

[gismo]

Help me out here a little sin/cosin guy!! Let say the winds are 90 degrees off your right wing. I would normally have the nose pointed way into the wind until just before touch down; or, use strong enough cross controls to have the right wings way low until just before touch down.

Your first choice is the way I do it except that...

In the first case, just above the touchdown point, I'd let go of the right rudder so the nose came around as I was getting the mains on the runway (usually, the right main would touch first).

I wouldn't "let go of the right rudder" as I touch down, I'd be adding plenty of left rudder to swing the nose far enough left to align the plane with the runway while rolling in enough right bank to keep the plane from drifting left (inertia plays a big part here too). Prior to that the nose was pointing right (into the wind) relative to the runway, but it was a coordinated crab (little or no rudder or bank)

Which engine are you saying to add power to? Adding power to the left would push the nose right; are you saying add it to the right to get better rudder control? What do you mean -- upwind engine?

I'm saying add power on the right (at or after touchdown on one or two main wheels) to keep the plane from making a right turn off the runway. It wants to point into the wind and the nosewheel doesn't have enough grip to prevent this until the plane is slow enough to fully weight it and possibly even then. The added power on the right (upwind) side both genertates a yaw force to the left and makes the rudder more effective.

BTW that thing with the sin(70) isn't something I do in the air. Generally I figure any wind coming from an angle greater than 60 from the runway heading is all crosswind.

 

[Dave Siciliano]

I look forward to discussing this with you!! In the Bonanza, I just used cross controls; dropped the right wing as I swung the nose around and got the right main on the ground. I was thinking in the twin, I would need thrust from the left engine to push the nose right, but I see what you're doing now. V E R Y I N T E R E S T I N G !!

BTW, my niece just called: they had a death in the familiy (Great Uncle) and will be at the funeral this weekend. Asked if I could come next weekend instead.

Dave

 

[TangoWhiskey]

Wondered if you made it back or got stopped by that ugliness in Kansas.

"Ugliness in Kansas" is the correct description for what was going on there. We spent the weekend at my brother and sister-in-law's in St. Joseph, MO (just north of Kansas City), driving home on Sunday. We hit the weather in Kansas (near Emporia) about 2:30 in the afternoon.

I've NEVER had to pull off to the side of the road, but we did on Sunday! EVERYBODY pulled over. All of a sudden, the rain picked up, the wind went WILD, the car started buffeting, the temp dropped from 60 to 48 in two minutes... we pulled over, put our flashers on like everyone else did, and in 4 minutes it went away just as soon as it started. It was scary though--couldn't see more than 40 feet in any direction, but the prairie grass was twisting and blowing and the car was shaking like all get out. Wondered if we had just driven into a tornado!

My sister-in-law's cousin is a weather chaser for the Weather Channel--a lot of the footage you see of those storms comes from him. Here's an interesting write-up he sent us about the storms on Sunday... as pilots always learning about how weather works, you'll find this interesting:

Well - 2005 continues to surprise everyone with the weather; just when we think it's done throwing curve balls, here comes another one! I chased a tornadic supercell near Junction City, Kansas yesterday. This particular type of setup is tricky ... basically there is a small window very close to the area of low pressure that allows moist, unstable air to mix in close to very cold air aloft, which allows for compact 'mini-supercells' to form on the NORTH side of the low pressure. Normally, tornadic supercells form in the warm sector of the storm along the warm front, or in front of the cold front, so this is a special scenario that scientists have been studying only in the past few years - but now that chasers are figuring out how to target this scenario, it is paying off. Yesterday I targed the cold-core storms, mainly because I was afraid the warm sector storms would be moving too quickly to safely chase. Once I arrived in the Junction City area, there were two storms to choose from. One going up the west side of Junction City that ultimately struck Ft. Riley and damaged about 31 homes as it moved north to Riley County, or another that was much closer to my location off of highway 177. I chose the closer storm and followed it north of Manhattan, where it produced a brief 'hollow' tornado as the storm was transitioning to outflow. Very interesting day. I wanted to be on the western storms, just because I knew that anything firing closer to KC would be very near or after dark. That turned out to be a safe guess, as that is just what happened. A cell tracked from Weston through Faucett very close to my mom's home, doing damage in Weston, where a building collapsed downtown and a tobacco barn was destroyed. Another storm produced a possible tornado in Excelsior Springs, where a factory was destroyed. Some friends of mine that I was in contact with during the chase caught the storm going through Junction City and got absolutely amazing pics and video. I've attached a few of my photos.

To see Scott Currens' video, go to his webpage at: http://www.violentplains.com ... thought I would let you know to beware, though - after the tornado hits a barn (and throws it about 300 feet straight up), it also hits a cattle lot, which is tough to see. One of the sad realities of these things.

The pictures he references are attached...

 

[Dave Krall CFII]

Your first choice is the way I do it except that...


I wouldn't "let go of the right rudder" as I touch down, I'd be adding plenty of left rudder to swing the nose far enough left to align the plane with the runway while rolling in enough right bank to keep the plane from drifting left (inertia plays a big part here too). Prior to that the nose was pointing right (into the wind) relative to the runway, but it was a coordinated crab (little or no rudder or bank)


I'm saying add power on the right (at or after touchdown on one or two main wheels) to keep the plane from making a right turn off the runway. It wants to point into the wind and the nosewheel doesn't have enough grip to prevent this until the plane is slow enough to fully weight it and possibly even then. The added power on the right (upwind) side both genertates a yaw force to the left and makes the rudder more effective.

BTW that thing with the sin(70) isn't something I do in the air. Generally I figure any wind coming from an angle greater than 60 from the runway heading is all crosswind.

Thanks for the details Lance,

Do you ever find yourself planting the nosewheel down with forward yoke/stick in high XWinds to gain steering authority (ouch !) ?

 

[Rudy]

We had a tornando watch here in SE KS on Sunday, every other county around us was under a warning and one touched down not to far from here. Its interesting, there will be warnings and the sirens will be going off and everyone just goes about there normal daily chores. No one gets to worked up about it, but then again it is pretty common.

 

[gismo]

Thanks for the details Lance,

Do you ever find yourself planting the nosewheel down with forward yoke/stick in high XWinds to gain steering authority (ouch !) ?

In a word... NO! Forcing the nose down can turn a fairly stable situation into a disaster quickly. If the nosewheel gets more grip on the pavement than the mains, all of a sudden the CG of the airplane is way behind the center of lateral resistance and the thing will want to swap ends worse than a taildragger landed in a crab. You don't have to get all the weight off the mains, just have more weight on the nosewheel than the main(s).