Track day July 4th with Motorhead.

[Marc W]

Just for the sake of discussion.... I have a commercial pilots license. Not currently working as one, but have a fair amount of time flying coast to coast on autopilot. One of the things that pilots are periodically checking and resetting is the altimeter. That tells you how high you are above SL and that setting is given by air traffic control stations all over the country. It will change over distance and changing weather/temps. It’s actually a pretty critical setting because airplanes fly at assigned altitudes depending on whether they are going east or west. You don’t want to fly head on into someone going the other direction because your altimeter wasn’t right. So that info is given every time you make contact with a controller. I have to assume that these apps are getting their DA info from these stations and there can’t be variances of a thousand ft at the same place. Maybe I’m wrong and that’s not where or how these apps are getting their info but if they are.... I would trust them over a handheld.

 

[moparjim]

Yeah , really good ET's , I noticed the humidity was low or what I consider low compared to here , I think that makes the most difference in how the car will run even if it's hot outside.

Yes the humidity and grains were lower than the last time out 2wks ago.
The last time in the heat the car was warm and iat's were high. Around the 1/8 mile I could feel the car start to pull harder then it fell on it's face at the end of the track. This time it didn't do either of those.

 

[moparjim]

Just for the sake of discussion.... I have a commercial pilots license. Not currently working as one, but have a fair amount of time flying coast to coast on autopilot. One of the things that pilots are periodically checking and resetting is the altimeter. That tells you how high you are above SL and that setting is given by air traffic control stations all over the country. It will change over distance and changing weather/temps. It’s actually a pretty critical setting because airplanes fly at assigned altitudes depending on whether they are going east or west. You don’t want to fly head on into someone going the other direction because your altimeter wasn’t right. So that info is given every time you make contact with a controller. I have to assume that these apps are getting their DA info from these stations and there can’t be variances of a thousand ft at the same place. Maybe I’m wrong and that’s not where or how these apps are getting their info but if they are.... I would trust them over a handheld.

The instructions for the handheld did mention setting the altitude or baro as a known factor so I used the altitude knowing that for sure.
After setting the altitude the DA did read different. I just can't recall the change. Even taking the Kestrel out of the equation there is often 600' +/- discrepancy between the apps.🤪

 

[BULL]

Well there you go I had not heard that. I was under the impression this was the way to go.

My experience (amateur) is that they are good for getting you to within 1000, or maybe even 500ft, but when you're standing there watching the DA instantly bang up and down by at LEAST several hundred ft (even after sending it in for repairs) that they aren't good for a precise DA.

Then the question is, what level of accuracy is needed, either for shooting, or for racing?


Does 200ft of DA really make that much of a difference?


I know for shooting, it did not, there were many other much more relevant factors...

 

[Marc W]

Maybe we should just start using different descriptions for DA. Hot, very hot, super hot, stupid f’n hot!!

 

[Marc W]

I would have placed the Kentucky race in the SFH catagory.

 

[BULL]

For example, my seat dyno (or the HP gauge on the dash) can't tell a bit of a difference in 1000DA delta, but you start talking about 2000, or 3000DA, NOW you're talking about a real difference in power...



.02

 

[moparjim]

I would have placed the Kentucky race in the SFH catagory.

It was like that here that weekend. ADO had grains at 105 humidity was in the 80% range I think and even though they had the temp at 85f I saw a thermometer at 40c in the shade so about 104f.
I felt like 🤢🤮💩.
The weekend before I wore my fire jacket to stay warm. LOL
Love the north. 🤣🤣

 

[moparjim]

For example, my seat dyno (or the HP gauge on the dash) can't tell a bit of a difference in 1000DA delta, but you start talking about 2000, or 3000DA, NOW you're talking about a real difference in power...



.02

That depends where the DA started before the 1000' I imagine. Unlike you I'm close to sea level to begin with.

 

[Mean Cat]

Well for racing , from what I've heard & noticed myself , for every 800>1000 DA is a 10th in ET , + or -

 

[Hpindy]

The kestrel is correct and is what I will be using ...... Well because I bought the damn thing .

Plus I compared it to a local shop with a $10K wether station and it was very close in every reading . It was +/- 1%.

Sent from my BBF100-2 using Tapatalk

 

[Marc W]

The kestrel is correct and is what I will be using ...... Well because I bought the damn thing .

Plus I compared it to a local shop with a $10K wether station and it was very close in every reading . It was +/- 1%.

Sent from my BBF100-2 using Tapatalk

Good to know! That means I ran a 8.90 at 3000’. I’ll take that!! 😝

 

[moparjim]

Good to know! That means I ran a 8.90 at 3000’. I’ll take that!! 😝

Others you were with are using a kestrel as info for their times.
So why not us. 🤣 If it is off hopefully it's off by about the same.😀

 

[Marc W]

Others you were with are using a kestrel as info for their times.
So why not us. 🤣 If it is off hopefully it's off by about the same.😀

That would explain why Speedy was being told it was higher. I know that humidity has to be a factor and that was off the map. As it cooled down the car was dripping wet. If I had windshield wipers I woulda used them!

 

[Hpindy]

Man now I have to buy a real weather station . Stay tuned ......

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[moparjim]

Man now I have to buy a real weather station . Stay tuned ......

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I thought you did. Then I did the same.🤷‍♂️

 

[Hpindy]

Well there seems to be some question on which method is correct . So if I can get my hands on a professional weather station it will help determine the accuracy of all the mentioned methods.

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[moparjim]

Well there seems to be some question on which method is correct . So if I can get my hands on a professional weather station it will help determine the accuracy of all the mentioned methods.

Sent from my BBF100-2 using Tapatalk

I'm using the kestrel as accurate at Napierville for a few reasons.
No nearby weather stations. All are about an hour away in or closer to Montreal.
The whole reason I bought this was because of the discrepancy in temperature at track physically or on the apps which are reading 15 to 20+ f lower which has to affect the DA readings.
2wks ago there was a racer that had a more expensive weather station. He is the one that mentioned temps in the 100's f and DA about 1100ft higher than the apps.
Another racer uses the track app for DA but has his own barometer and thermometer to log with.
His temps were off pretty much the same as everyone else's.
Here is the ADO app's readings for this day.
That just about 20f discrepancy will for sure affect the DA readings. As well as how far off anything else may be.

 

[vortecd]

My thought is this is just like a dyno, they all read different. Pick one and track it that way. I use the drag times da tracker. Unfortunately nothing is going to be perfect but if there is some what of consistency then you have some info to go by

 

[moparjim]

My thought is this is just like a dyno, they all read different. Pick one and track it that way. I use the drag times da tracker. Unfortunately nothing is going to be perfect but if there is some what of consistency then you have some info to go by

Kind of my thinking. I will be using the Kestrel from now on . Well because I have it. And it at least knows how hot it is outside. LOL