3 man bobsled has a yaw string?? Is the track wide enough to yaw?

On Saturday, February 19, 2022 at 10:53:48 PM UTC-5, Glenn Betzoldt wrote:
> 3 man bobsled has a yaw string?? Is the track wide enough to yaw?

I saw 1, 2 and 4. No 3.
Yep- every bit of yaw not needed for path control is drag, both aerodynamic and mechanical. With the margin of victory in the 10's of a second over a minute every little bit counts. Most of the loss is probably mechanical when a runner gets off the perfect path. Notably the Germans cleaned up with slightly better sleds.
I kind of wondered why some joints were not taped.
Interesting to watch.
UH

On Sunday, February 20, 2022 at 10:17:45 AM UTC-5, Hank Nixon wrote:
> On Saturday, February 19, 2022 at 10:53:48 PM UTC-5, Glenn Betzoldt wrote:
> > 3 man bobsled has a yaw string?? Is the track wide enough to yaw?
> I saw 1, 2 and 4. No 3.
> Yep- every bit of yaw not needed for path control is drag, both aerodynamic and mechanical. With the margin of victory in the 10's of a second over a minute every little bit counts. Most of the loss is probably mechanical when a runner gets off the perfect path. Notably the Germans cleaned up with slightly better sleds.
> I kind of wondered why some joints were not taped.
> Interesting to watch.
> UH

Gliding, not sliding.

On Saturday, February 19, 2022 at 8:53:48 PM UTC-7, Glenn Betzoldt wrote:
> 3 man bobsled has a yaw string?? Is the track wide enough to yaw?
MK IV yaw string? I think they would go faster.

Sean Franke

The T-33, F-80, F-4, F-14 and probably a lot of other jet aircraft have
yaw strings, too.

Dan
5J

On 2/20/22 08:46, Sean Franke wrote:
> On Saturday, February 19, 2022 at 8:53:48 PM UTC-7, Glenn Betzoldt wrote:
>> 3 man bobsled has a yaw string?? Is the track wide enough to yaw?
> MK IV yaw string? I think they would go faster.
>
> Sean Franke

The only yarn employed in this discussion is the acceptance that it's a yaw string. It's a telemetry antennae. Think the bobsled pilot doesn't know which way the relative "wind" is flowing in an enclosed track? Look closer; the "yawstring" is pointing straight up.

https://fox40.com/sports/humphries-jones-win-historic-world-bobsled-title-for-us/

On Sunday, February 20, 2022 at 10:56:08 AM UTC-8, phlyi...@gmail.com wrote:
> The only yarn employed in this discussion is the acceptance that it's a yaw string. It's a telemetry antennae. Think the bobsled pilot doesn't know which way the relative "wind" is flowing in an enclosed track? Look closer; the "yawstring" is pointing straight up.
>
> https://fox40.com/sports/humphries-jones-win-historic-world-bobsled-title-for-us/

Agreed. Not to mention the fact that the bobsled is not part of the airmass, it runs on the ground on an outdoor track with presumably some wind and so a yaw string would have no valuable info to give to the sled pilot. I thought as glider pilots we should understand that at least! :)

On Sunday, February 20, 2022 at 8:17:45 AM UTC-7, Hank Nixon wrote:
> On Saturday, February 19, 2022 at 10:53:48 PM UTC-5, Glenn Betzoldt wrote:
> > 3 man bobsled has a yaw string?? Is the track wide enough to yaw?
> I saw 1, 2 and 4. No 3.
> Yep- every bit of yaw not needed for path control is drag, both aerodynamic and mechanical. With the margin of victory in the 10's of a second over a minute every little bit counts. Most of the loss is probably mechanical when a runner gets off the perfect path. Notably the Germans cleaned up with slightly better sleds.
> I kind of wondered why some joints were not taped.
> Interesting to watch.
> UH
Other than some rule preventing those joints being taped, I see quite a bit of movement between those joints. I think the shear forces would make it difficult to keep that tape in one piece.

On Thursday, March 3, 2022 at 10:18:32 PM UTC-6, Clay Thomas wrote:
> On Sunday, February 20, 2022 at 8:17:45 AM UTC-7, Hank Nixon wrote:
> > On Saturday, February 19, 2022 at 10:53:48 PM UTC-5, Glenn Betzoldt wrote:
> > > 3 man bobsled has a yaw string?? Is the track wide enough to yaw?
> > I saw 1, 2 and 4. No 3.
> > Yep- every bit of yaw not needed for path control is drag, both aerodynamic and mechanical. With the margin of victory in the 10's of a second over a minute every little bit counts. Most of the loss is probably mechanical when a runner gets off the perfect path. Notably the Germans cleaned up with slightly better sleds.
> > I kind of wondered why some joints were not taped.
> > Interesting to watch.
> > UH
> Other than some rule preventing those joints being taped, I see quite a bit of movement between those joints. I think the shear forces would make it difficult to keep that tape in one piece.

Probably explains why the German bobsleigh teams have performed so poorly over the last decade+ at the Olympics! But let's give them the benefit of the doubt and assume they know better than to use a yaw string (as useful as putting one on the cowling of your Cessna 150). The large gap between the 2 halves of the hull is there by design as it allows both a twisting action (a flex which keeps the 4 blade-runners in contact with the ice at high g) and to assist the pilot in steering. Aerodynamic taping would defeat these features of course. In the video below starting at about 2min in, one can see how this works (the camcorder is just positioned ahead of the pilot's feet looking towards the gap).
https://youtube.com/watch?v=gQeh0fTpwO0&feature=share

I may not be a German engineer, but I slept with one last night!
Phyllis