Headwinds

[mike57]

Just got back from a bike ride into a stiff headwind part of the way, it got me thinking:

Do drivers notice strong head (or tail) winds affecting performance of their units?

 

[fgwrich]

Just got back from a bike ride into a stiff headwind part of the way, it got me thinking:

Do drivers notice strong head (or tail) winds affecting performance of their units?

I've often heard it said that GWR's 165s perform better with a tailwind and worse in a headwind, but then again the Turbo's can be lacklustre at the best of times...

 

[hexagon789]

Just got back from a bike ride into a stiff headwind part of the way, it got me thinking:

Do drivers notice strong head (or tail) winds affecting performance of their units?

I know particularly strong ones can affect slab fronted units noticeably enough, it came up in a thread a few years back. Something along the lines of a stretch of line where a 156 could do 70 uphill before braking for a station but in bad headwinds, sometimes only 65 could be achieved.

Can't remember the nature of the thread sorry.

 

[Merle Haggard]

Don't sidewinds have an effect? Perhaps in the old days of goods trains (flanges forced against the rail) more than now, though.

 

[irish_rail]

I've often thought about this on very windy days, but must confess I've never noticed any real change although admittedly I drive mainly pointy stuff which would probably be less affected.

 

[owidoe]

I've often heard it said that GWR's 165s perform better with a tailwind and worse in a headwind, but then again the Turbo's can be lacklustre at the best of times...

One wonders why units without end doors are ever built without pointy noses, if that's the case!

 

[bluesfromagun]

It does make a small difference. A strong headwind tends to mean you won't coast as well. For example, a route I work has a section where the speeds drop 90 - 80 - 70 - 60 in fairly rapid succession. Normally you'd need to use a little step one brake for each reduction in speed, but if it's particularly windy you can coast and hit them all perfectly without ever touching the brake.
To be fair I've only really noticed this if it's a 158 I'm driving, and they don't coast well at the best of times.

 

[King Lazy]

I concur. I have a certain where rather than accelerate to linespeed I hit a certain speed, coast and let the gradient take me to linespeed. Just as you reach linespeed the gradient changes and you don’t overspeed.

However, on certain days you only get within 3-4 mph of linespeed.

Those days are noticeably windy.

Anecdotally it seems that you need a fairly strong wind to make a difference but it certainly doesn’t need to be a full-on storm. I suspect a lot depends on how much of a true headwind it is or whether it is hitting at an angle.

But to answer the original question. Yes, I am convinced I have noticed an effect that in my unscientific view can only relate to a headwind.

 

[Spartacus]

One wonders why units without end doors are ever built without pointy noses, if that's the case!

Pointy noses take up more material and are more difficult to make, so are more expensive. They also take up space, so you either have a longer vehicle keeping the same passenger space, or less passenger space.

I'm sure I read a BREL or similar study years ago that said that as the frontal area is relatively small it doesn't make a huge difference, and that a cross wind was worse, even for then 'modern' stock. Of course you're rarely going to get a situation where you're train's heading directly into the wind, at least for very long due to the nature of lines twisting and turning, and that if it's windy there's almost always going to be some element of cross wind.

 

[furnessvale]

Just got back from a bike ride into a stiff headwind part of the way, it got me thinking:

Do drivers notice strong head (or tail) winds affecting performance of their units?

Given the small surface area of the front of a train, I doubt that would be significant. In any case, the "pointy" back end of a train is more relevant in aerodynamic terms than the front, which tends to generate its own false nose cone of still air.

What is more significant is the drag along the length of the train. A memorable example of this were the bare body shells of Rootes group cars on the WCML to Scotland. These caused so much drage that a class 40 with 20 carflats carrying these bodies, 8 to a flat, double stacked on open pallets, had to use significant power on downhill sections to maintain timings and could not coast.

 

[alistairlees]

Just got back from a bike ride into a stiff headwind part of the way, it got me thinking:

Do drivers notice strong head (or tail) winds affecting performance of their units?

Yes it does, at least for class 153 units. I was told by the then MD of Anglia Railways in around 2003, in answer to the question "Why is on time performance poor recently for Ipswich to Cambridge / Peterborough services?" that the reason was that there had been strong westerly winds, so the 153s could never keep to time in one direction (but were fine in the other).

 

[Deepgreen]

It has been said that loco streamlining has no significant effect below about 80mph. I think Gresley did tests when looking at the A4s' design. Side winds on long trains can be significant. There was the case of the loco on the turntable at Hawes in the early 20th century which was caught by a side wind and spun round uncontrollably for a long time! I also recall the London to Brighton speed run with a pair of 319s where all the windows were kept closed to optimise air-smoothing!

 

[mike57]

Yes it does, at least for class 153 units. I was told by the then MD of Anglia Railways in around 2003, in answer to the question "Why is on time performance poor recently for Ipswich to Cambridge / Peterborough services?" that the reason was that there had been strong westerly winds, so the 153s could never keep to time in one direction (but were fine in the other).

That makes sense, a single 153 has the same frontal area as something with more engines/carriages, so assuming wind resistance into a head wind is then similar for say 153 and 156 but that resistance is not 'divided' between the units in the case of a 153.

I'm sure I read a BREL or similar study years ago that said that as the frontal area is relatively small it doesn't make a huge difference, and that a cross wind was worse, even for then 'modern' stock

Certainly from a cycling perspective a strong crosswind seems to take more effort, even if its exactly at 90 deg to direction of travel, where in theory it is neither helping or hindering

 

[Deepgreen]

I know particularly strong ones can affect slab fronted units noticeably enough, it came up in a thread a few years back. Something along the lines of a stretch of line where a 156 could do 70 uphill before braking for a station but in bad headwinds, sometimes only 65 could be achieved.

Can't remember the nature of the thread sorry.

The trouble is, with different individual units having slight variations in output, for a number of reasons, it's very hard to establish the specific impact of wind. It really needs a wind-tunnel with instrumentation to measure the effects. Going back to the OP's post, I recall a cycle ride from Bridge of Orchy to Fort William in a south-easterly gale where I hardly needed to pedal at all - that happens so rarely!

 

[berwicksfinest]

From a freight perspective, Our Plasmor service (when empty) and intermodals when part loaded, are most certainly noted for Cross and headwinds to give the 66s a clear out

 

[43066]

During the storms last winter I can remember feeling my entire train lurching to and fro as it was buffeted by the wind. Never noticed any change in performance, though.

 

[mike57]

I recall a cycle ride from Bridge of Orchy to Fort William in a south-easterly gale where I hardly needed to pedal at all - that happens so rarely!

Be thankful you didnt decide to start from Fort William. I cycled into nearly 40mph headwind once last winter and forward progress was nearly impossible, ride was abandonded after a very short time.

 

[McRhu]

I'm sure I remember reading about the 29s experiencing dramatic loss of speed on the Horseshoe due to strong side winds, causing flange rub. Might have been in John Thomas' book.

 

[Sean Emmett]

Vale of York on the ECML, and Vale of White Horse on GWR both open to W - NW winds which had a noticeable effect on loco hauled trains

When the IETs were first introduced I timed one on diesel which just about reached 125 mph eastbound near Didcot, with a favourable wind.