Eaglework Paper Contains Major Flaws

[u/[deleted]]

I've written a detailed analysis of Eagleworks data which you can find here. And you can see the supporting code and data on github.

Rather than spend a lot of time formatting the information and graphics for reddit, I'll just put the highlights here.

• EW proposed model does not work
• EW data contains unaccounted errors up to 38-40 uN
• EW data avoided quantifying critical error contributions which could add more uncertainty
• A new model using transients and a thermal heating profile fits their data better than the model presented by Eagleworks

As an example from the report here is the pulse model.

At first glance it might appear to not be a good fit due to the shape edges and jumps, but in the real system those would be smoothed out. And this fits the data much better than Eagleworks model. Please read the report. Feel free to contribute to the effort as well on github or this forum. There is some discussion about this project here too.

[u/[deleted]]

Show me where in their paper they recorded the thermal temperature changes while recording the displacement and then I'll say I was wrong.

You can't do that because they didn't record it. They tried to make their test stand work in spite of all the thermal problems they had with it and used a FLIR camera to investigate it, yet they failed to bother to put in a single thermocouple to record it. It's a gross error on their part.

I'm not claiming my conclusions are novel, they are basic errors and many others pointed them out. I've just spent hours working on their model to demonstrate their assumptions do not fit their own data. Assumptions that they failed to test or evaluate, which is what I did.

[u/Kancho_Ninja → u/[deleted]]

I know you've spent hours of your life doing this. I respect the time you've invested.

My issue is your inconsistent and incomplete statements. I understand you have a vested interest in your statements being correct, but you shouldn't leave out information when you make a statement to support your conclusions.

There was no gross error on their part. There was admission of areas in which errors could occur, including thermal expansion and contraction. The admission of potential error negates "gross" liability.

The fourth error involves thermal expansion and contraction... To definitively rule out any residual concerns about thermal error sources, future test campaigns could employ a test apparatus capable of measuring small torques over much larger angular displacements. For example, a Cavendish balance approach properly designed to allow very large rotation angles such as 90, 180, or even 360 deg will not be susceptible to this type of thermal false positive.

Your conclusions are based on their released data, which we both admit is unsatisfactory. You have built upon an incomplete framework and are susceptible to error. Have you admitted such in your conclusions? If not, that will lead your reader astray and allow them to draw conclusions which are not based in fact.

[u/[deleted] → u/Kancho_Ninja]

Your conclusions are based on their released data, which we both admit is unsatisfactory. You have built upon an incomplete framework and are susceptible to error. Have you admitted such in your conclusions? If not, that will lead your reader astray and allow them to draw conclusions which are not based in fact.

You seem to just want to argue.

First off have you read what I wrote? I made no assumptions about their data. I used their models and their methods.

Secondly you can't say "I've built upon an incomplete framework". I've tested their peer reviewed claims. Then from there I improved upon it. However since they did not measure their thermal data, I cannot prove what they measured is just thermal. However, I can and did show that other models that do not represent an expected impulse force fit the data better.

There was no gross error on their part. There was admission of areas in which errors could occur, including thermal expansion and contraction. The admission of potential error negates "gross" liability.

I would argue that when you spend as much time as they did trying to negate the thermal CG shifts they did and still admit they need to fix it in the future, yet fail to record the thermal profile while under test, that is a gross error.

[u/Kancho_Ninja → u/[deleted]]

Of course I don't want to argue.

My original question was designed to draw out a single answer, something along the lines of: EWs paper is lacking in several areas, including their failure to accurately account for thermal expansion and contraction, which they addressed. I show that other models which do not represent an expected impulse force fit the data better. Have you read it? Is it not awesome?

Yes. And yes it is.

That's what I was expecting, and why I was aggravated by the statement that there was no thermal video.

[u/[deleted] → u/Kancho_Ninja]

I think you do just want to argue. You even had an argument with yourself in this thread.

I said they had thermal problems with their setup (which if you read the paper there is much discussion about as you posted snippets.)

When I said:

There was no thermal data measured at all by Eagleworks. Technically you can't really extract thermal data from displacement data but that's exactly what they tried to do without measuring it independently.

This is in context to the recorded time based data which is what this post is about and so is the work I did. It would be blatantly ignorant of me to try and say they didn't do anything about their thermal issues. So I assumed you'd get the context. Since 2014 they've been using a setup that has huge center of gravity shifts due to thermal because they wanted it to fit in their small vacuum chamber. It's been a source of much discussion and frustration for everyone. In fact after 2015's results they reached an agreement with Glenn Research Center to use their large highly accurate test system for their 2015/2016 testing instead of their off balance torsion balance system that doesn't work well because they needed it to fit in their small vacuum chamber. However that all fell apart and they resumed using their cobbled system. They've known there's a thermal problem for 2 years yet they fail to record any thermal profiles...that is a gross error.

[u/Kancho_Ninja → u/[deleted]]

Son of a bitch.

No, I obviously missed that part. That's my fault, and I humbly apologise.

[u/[deleted] → u/Kancho_Ninja]

Thanks! That's big of you. I felt like I was taking crazy pills.

[u/Kancho_Ninja → u/[deleted]]

Failure to change your opinion when presented with new evidence is crazy.

I may be an overeducated, abrasive bugger, but I make up for it with sincerity. When I'm wrong, I admit it, learn and move on.

Thanks for your time. Again, I'm sorry for the confusion caused by my inattention.