Merged DDWFTTW in a “Real” Wind

[humber]

This does not mean that the BB's propeller has some magical new property called "tacking force". That is a term you pulled out of your own fundament.

If you like. Find one reference in a text book that even alludes to a tacking prop. Props produce thrust, they don't tack in any way, shape or form.

 

[jduffy77]

"extra" over and above the usual thrust.

There is no extra thrust. Just the usual thrust.

There is no support from anywhere for tacking props, because it is a fabrication.

Humber, educate yourself. When I Google ("angle of attack" propeller) I get 787000 hits.

 

[Llyricist]

"extra" over and above the usual thrust.
There is no support from anywhere for tacking props, because it is a fabrication. That does lend weight to the claim that the trial may be similarly tainted, as does reluctance to provide the raw data.

Nobody but you has ever claimed any extra force above the usual thrust. Thrust is a result of the lift caused the propeller blades' airfoils and their AOA. A tacking sailboat is propelled as a result of lift caused by it's airfoil and its AOA.

 

[CORed]

"extra" over and above the usual thrust.
There is no support from anywhere for tacking props, because it is a fabrication. That does lend weight to the claim that the trial may be similarly tainted, as does reluctance to provide the raw data.

Nobody ever claimed that there is any extra force. The whole tacking thing was intended as an explanation of how the prop develops its thrust. You know, the thrust you keep pretending doesn't exist when you refuse to understand how the ddwftw cart works, on the treadmill or in the "real" wind.

 

[I Ratant]

Determining how much force the foam wind carts would need to move.
A simple mechanism.
The cup is attached to the cart at the propellor center line, and when filled with coffee will drop when the weight of coffee in the cup overcomes the rolling friction. Empty weight .05 oz.
For the free-wheeling prop cart, the cup itself was almost enough weight to start the cart moving.
Adding a minor amount of coffee and it moved forward. Too little coffee to weigh.
The driven cart had the same amount of rolling resistance with the drive from the wheels to the propellor disconnected.
When connected, it wouldn't move at all until 18 ml of coffee was added to the cup.

 

[ThinAirDesigns]

Why won't you make the raw trial data available, Chief?

Another lie.

It is available, has always been available and we have told you exactly how to get it repeatedly.

JB

 

[CORed]

Another lie.

It is available, has always been available and we have told you exactly how to get it repeatedly.

JB

That seemed pretty fishy to me. Where did he get the data to make his charts of variation in wind speed and direction? Is there some other raw data he's claiming you haven't released?

 

[humber]

Humber, people are going to think you have a learning disability.

U mean 'bout the tukcing prip?

Tacking and angle of attack are synonyms. One word is used in sailing the other in propeller aerodynamics. If you go in a stationary store in the United States and ask for a rubber they might call the police.

Not if the assistant is female.

That does not mean that erasers are a fabrication.

Let me see. In the UK, it's called attack angle, but in the US, it's called tacking. British boats attack, and American boats tack?

The blade is not "at an angle", but is an airfoil. There is a twist along its length, because the angular velocity changes along its length. Its function is to accelerate the air. It takes in angular power at the shaft, and transfers that to the by means of momentum exchange, so producing thrust.
A sail takes energy from the air, and uses the lateral force available from not being ddw. There is no similarity whatsoever.

 

[humber]

Another lie.

It is available, has always been available and we have told you exactly how to get it repeatedly.

JB

Yes, like the high definition videos that you said were available, but were never made so. You made the same sort of half-truths as above.
Like the trial rules that never appeared. The instruments that never appeared.
Like the constantly changing details of the cart. Like a cart that is one minute 350lb, and 650lb the next. Prop mass changes from 2kg to 10kg. Like the NALSA invitation that turned out to be a talk at the staff yacht club, and the AIAA in a community centre.
Like steady-state becoming a short jaunt. Ddw to "whatever".
Who said that acceleration was a benchmark? It isn't.

NALSA do not have a contact for that information other than via membership. You do have that data, so what is the problem?

 

[CORed]

U mean 'bout the tukcing prip?


Not if the assistant is female.


Let me see. In the UK, it's called attack angle, but in the US, it's called tacking. British boats attack, and American boats tack?

The blade is not "at an angle", but is an airfoil. There is a twist along its length, because the angular velocity changes along its length. Its function is to accelerate the air. It takes in angular power at the shaft, and transfers that to the by means of momentum exchange, so producing thrust.
A sail takes energy from the air, and uses the lateral force available from not being ddw. There is no similarity whatsoever.

So what is the purpose of the twist in the blade, humber? Could it have something to do with the changing angle of attack relative to speed?

ETA: Actually, the sail on a broad reach and propeller blade do exactly the same thing. Of course you would have to understand relative motion and frames of reference to grasp that fact.

 

[ThinAirDesigns]

That seemed pretty fishy to me. Where did he get the data to make his charts of variation in wind speed and direction? Is there some other raw data he's claiming you haven't released?

We have said from the start that we have a copy of the data that NALSA collected and that *anyone* can also get a copy of the raw data from NALSA upon request.

I know for a fact that if asked they will provide it.

Humber would rather tell lies than make one request of NALSA for the data and get it.

Us handing out data would be of no value since we would only be accused of having ********** with it (as humber already does even though he got it from them and not us).

JB

 

[A.T.]

Actually, the sail on a broad reach and propeller blade do exactly the same thing.

Yep.

Sail on broad reach constrained by keel:



Propeller blade constrained by coupling to wheels:

 

[jduffy77]

The blade is not "at an angle", but is an airfoil. There is a twist along its length, because the angular velocity changes along its length. Its function is to accelerate the air. It takes in angular power at the shaft, and transfers that to the by means of momentum exchange, so producing thrust.

Other then having nothing do do with propellers I can tell you when you talk about "taking in angular power at the shaft" it definitely sounds like we frequent different clubs.

A sail takes energy from the air, and uses the lateral force available from not being ddw. There is no similarity whatsoever.

If in the Humberverse "no similarity" means "they are identical" then you are correct. Otherwise, fail.

 

[Jack by the hedge]

The blade is not "at an angle", but is an airfoil.

And so is the sail.

There is a twist along its length, because the angular velocity changes along its length.

Thereby retaining its sail-like airfoil section and appropriate angle of attack along its length. Another clue that we're right.

Its function is to accelerate the air.

Its function is to generate thrust, just like the sail and using the same aerodynamics as the sail.

It takes in angular power at the shaft, and transfers that to the by means of momentum exchange, so producing thrust.

The sail also experiences torque applied at the root of its mast, and it likewise extracts momentum by diverting the air, producing thrust.

A sail takes energy from the air, and uses the lateral force available from not being ddw.

That's the same thing described from a different frame of reference. The prop blades have, of course, considerable lateral speed relative to DDW.

There is no similarity whatsoever.

I think everyone else can see that you are determinedly wrong about that.

 

[humber]

More lies - from a delusional liar.

I suspect I'll be suspended for this - because it's OK for humber to lie about me, insult me, and post things that are clearly delusional. But I'm not supposed to point out that he's lying and delusional.

Everyone, including the Carteers, got the impression that Ames was an official matter. RP thought so, and wanted to make video and arrangements for a video Q&A.
AIAA was at the Hacker DoJo Community centre.
I asked you repeatedly for the HD video of the first runs, and was told all sorts of crap big files, don't have it...

I could add denying that you knew Steve Smith...oh, I have.

The original claim was for steady state, and there is no doubt about that.
JB proposed a long run - 2.5miles I think etc.

The instruments, such as the pitot tubes and force gauges were never made operable.

You did not ask if the test conditions and rules were acceptable, yet used the result to make snide remarks about Platt and Allain. A forced victory.

So which are lies?

 

[ThinAirDesigns]

Everyone, including the Carteers, got the impression that Ames was an official matter. RP thought so, and wanted to make video and arrangements for a video Q&A.
AIAA was at the Hacker DoJo Community centre.
I asked you repeatedly for the HD video of the first runs, and was told all sorts of crap big files, don't have it...

I could add denying that you knew Steve Smith...oh, I have.

The original claim was for steady state, and there is no doubt about that.
JB proposed a long run - 2.5miles I think etc.

The instruments, such as the pitot tubes and force gauges were never made operable.

You did not ask if the test conditions and rules were acceptable, yet used the result to make snide remarks about Platt and Allain. A forced victory.

So which are lies?

Almost the entirety of what you said right there. You got the location of the official monthly AIAA chapter meeting correct. Congrats.

JB

 

[humber]

We have said from the start that we have a copy of the data that NALSA collected and that *anyone* can also get a copy of the raw data from NALSA upon request.

I know for a fact that if asked they will provide it.

Report says.
"If any NALSA Board Member has questions or would like to see additional data or information on any of the above please contact either of us."

Humber would rather tell lies than make one request of NALSA for the data and get it.

I asked you. Why not? Post it on the website. Quicker. Certain.

Us handing out data would be of no value since we would only be accused of having ********** with it (as humber already does even though he got it from them and not us).
JB

Nice footwork. I got the data from the one page that has all that is available.
http://www.nalsa.org/DownWind.html
No mention of where to get the remainder.
There is a large list of files on Kimball Livingston's site that is not available.
Interesting stuff like the wind speed taken from the CV and the vane readings.

As for the modifications, I did ask you to explain them. You showed no interest at all, even if you were responsible or not.

That modification shows up as a difference between your chart and the 10seconds of available NALSA data.
I could have changed the data that I do have, but didn't, and NALSA will have a record that can be used as reference should I try.

 

[humber]

Almost the entirety of what you said right there. You got the location of the official monthly AIAA chapter meeting correct. Congrats.

JB

And the HD video..word games..all on the forum.
It is a matter of record that you denied knowing Smith. Claimed no connection.
Posting my email address you got from him...
And the instruments, they were working?
And you didn't post a long run using balloons? Sure now...
How about steady-state? Endlessly repeated.
And Ames too...RP's daughter was to film it etc...

 

[humber]

So what is the purpose of the twist in the blade, humber? Could it have something to do with the changing angle of attack relative to speed?

ETA: Actually, the sail on a broad reach and propeller blade do exactly the same thing. Of course you would have to understand relative motion and frames of reference to grasp that fact.

Give it up, there is no such thing as a tacking prop, and the next request will be for you to show the math from the books you say do. A long history to check. When the effect was first noted, how Doughty Propellers, Cheltenham, UK, don't seem to know of it, when the wanted some test equipment built. No spec. No mention.

 

[Jack by the hedge]

Give it up, there is no such thing as a tacking prop...

One more time: It's not a "tacking propeller", it's a "propeller". It's as if the last few pages of this thread never happened.

You're just being deliberately obtuse now. You are pretending not to understand just to avoid admitting you are wrong, just like your earlier "it's complicated" evasion when attempting to squirm out of admitting you made a mistake about stacking pairs of weighing scales. It's painful to read.