Steve Hinton Jr.

[wingman]

Check out the yaw string...

Photo from Pylon 4 on Friday.

Neal

[frostkg]

Re: Steve Hinton Jr.

What am i looking for. Is it that thing in front of the canopy three feet or so?

[Big_Jim]

Re: Steve Hinton Jr.

Yes, the yaw string is about a two-foot long piece of string mounted on the top of the cowling.

A $1 piece of equipment that is the best judge of whether the kid is 'stepping on the ball' correctly....and it's directly in his line of sight.

[wingman]

Re: Steve Hinton Jr.

The man surely does fly a pretty line...

Photo from Pylon 8 during the Gold Race on Sunday.

Neal

[Reever]

Re: Steve Hinton Jr.

Neal,
Awesome shots.

Steve

[wingman]

Re: Steve Hinton Jr.

Thank you Steve. There will be more. I'm still wading through and culling out the rejects from the thousands of shots from race week, and posting up a few that stand out and tell a bit of a story.

Neal

[frostkg]

Re: Steve Hinton Jr.

Yes, the yaw string is about a two-foot long piece of string mounted on the top of the cowling.

A $1 piece of equipment that is the best judge of whether the kid is 'stepping on the ball' correctly....and it's directly in his line of sight.

Cool. I did not see one of those on some recently posted 232 and Bear photos. Who else uses one?

[Randy Haskin]

Re: Steve Hinton Jr.

Okay, I'll be the dummy here: is a straight yaw string really an issue in pylon racing?

In my experience doing high-G turns in a swept-wing jet, the turn is primarily a function of back-stick pressure. Yaw has very, very little to do with it. While roll needs to be constantly minded (altitude control under G is a "roll" function, modulating the placement of the lift vector), it doesn't control the turn like it might in a light aircraft making a 30-degree bank turn. That means not much adverse yaw, and that means no need to tweak the rudder to keep the airplane going straight.

My feet are on the cockpit floor during a high-G turning fight and only touch the rudders when things slow down (and the rudders become more effective in roll control than the ailerons) or if a specific maneuver demands it.

In "my world", a semi-trained monkey could lay on a 6G turn with the yaw string flowing straight down the centerline of the fuselage. It would not be an indicator of any particular aspect of skill in making a good turn.

So...how's it different in a Mustang?

[Big_Jim]

Re: Steve Hinton Jr.

So...how's it different in a Mustang?

Oh, you know the answer to it...you're just not seeing it because you're not used to flying a plane with a big prop swinging round and round up front. I'll use the Kerch method of flying the course. Set race power and leave it. The plane is going to speed up and slow down depending on how hard you're turning or how smooth your flying is. Smoother is faster. With the rudder trimmed for 'speed' any variation in that speed is going to change the nose direction both up and down and side to side...and anytime you enter a turn you induce adverse yaw...which is essentially induced drag. A plane that is out of trim is going to be slower. So my guess is that you're constantly on the rudders to keep that yaw string centered...but it's so second nature that you don't even think about it. Maybe we can get BCIV to jump in with his explanation of the old 3-blade on the Bear and how it constantly required dancing on the rudder pedals to keep the plane going in the right direction.

[Ronbo]

Re: Steve Hinton Jr.

I believe wing dihedral and prop wash plays a factor in keeping the ball/string centered vs the zero dihedral of a jet. Rudder is more effective and needs to be for that reason vs the smaller rudders of a jet...I could be oversimplifying it or way off...?

[flyboycpa]

Re: Steve Hinton Jr.

Yeah,

I'm not sure which fighter you fly, Randy, but I'd never compare a modern-day fighter's aerodynamic needs to a completely-unautomated, over-engined, plane from the 40's flying some 20% faster than it's meant to.

In prop planes we have turning tendencies (torque, gyroscopic precession, slipstream effect, and p-factor). Considering the horsepower of a race motor, there are a LOT of those 4-factors working against keeping a well-flown line along a race course.

You gotta have skillz, and lots of them. Steve-O clearly does. If that string didn't need to be there, it wouldn't be there.

fb

[Randy Haskin]

Re: Steve Hinton Jr.

I'm not sure which fighter you fly, Randy, but I'd never compare a modern-day fighter's aerodynamic needs to a completely-unautomated, over-engined, plane from the 40's flying some 20% faster than it's meant to.

In prop planes we have turning tendencies (torque, gyroscopic precession, slipstream effect, and p-factor). Considering the horsepower of a race motor, there are a LOT of those 4-factors working against keeping a well-flown line along a race course.

Well, thanks, but in addition to 15 years flying fighters and trainers for the USAF, I am also a civilian pilot and instructor, ATP-SE/ME/CFII/MEI, so I'm well enough acquainted with turning tendencies.

Here's a fun fact for ya: jet engines have a fair bit of rotating mass themselves, and they're going at a much higher RPM, so although there is no torque, P-factor, or spiraling slipstream, there's plenty of right-hand-rule going on when they turn, too.

Automated flight controls don't have anything to do with it, either. The scenario I was describing applies just as much to the F-15 with a flight control computer as it does in the T-38 which is just as manual as any WWII fighter (outside of the hydraulics).

Anyway, that wasn't really my question, it isn't about the purpose of a yaw string conceptually.

I was actually wondering about the top modified unlimiteds, with vertical stabs that have altered angles of incidence, engine installations with altered thrust planes and thrust lines, etc. How do they handle the corners, how much rudder do they really need. Are they like a NASCAR racer where their natural state of being is going around the corners and they have to be 'forced' to drive straight.

If that string didn't need to be there, it wouldn't be there.

Well, given how many unlimiteds don't have one, and historically haven't had one, (and of course there are others, like Voodoo, that do), that's not necessarily a self-evident deduction.

So, thus the question.

[xmh53wrench]

Re: Steve Hinton Jr.

I was actually wondering about the top modified unlimiteds, with vertical stabs that have altered angles of incidence, engine installations with altered thrust planes and thrust lines, etc. How do they handle the corners, how much rudder do they really need. Are they like a NASCAR racer where their natural state of being is going around the corners and they have to be 'forced' to drive straight.

Thanks Randy, since my peaked interest in air racing over the past year and my background in turning right to go left on the ground, I have pondered this many many times. Glad you asked the question, I would love to know the answer to this, but I have a feeling.....well.....we will see.

[L.E.D.]

Re: Steve Hinton Jr.

It's almost certainly a game of inches, keeping things really smooth, as much as anything. Keeping things coordinated keeps G in line with bank angle, and keeps drag down. I've seen racers fly with what looks like top rudder and too much bank, particularly in F-1 and biplanes, and have thought that it may be a function of experience flying low and with large bank angles while attention is outside the cockpit. A reference like a yaw string would be very helpful, and several of the F-1s have them.

[TwoZeroWest]

Re: Steve Hinton Jr.

To my mind, it's really simple: A straight yaw string means properly coordinated flight. In all cases I can think of this is a measure of two things that a close race could come down to - pilot skill and maximum efficiency.

I've seen yaw strings affixed to anything from a Schweizer 2-33 on up (including military jets). They provide the pilot with the most fundamental information about slip and skid possible - regardless of the performance of the aircraft. Use 'em or don't but in racing, that info can make a difference.