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Search: Posts Made By: Owain Glyndwr
Showing results 1 to 35 of 41
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Forum: Tech Log
3rd Dec 2012, 19:31
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Yes, I would agree with that for that particular...

Yes, I would agree with that for that particular picture. As I said, my hope was that people would interpolate for greater heights, although that of course depends to some extent on there being some...
Forum: Tech Log
3rd Dec 2012, 18:02
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

But the static pressure on the wing surface does...

But the static pressure on the wing surface does reflect the local velocity at that station outside the boundary layer does it not?



No problem with Sir Isaac and changes to the integrated...
Forum: Tech Log
3rd Dec 2012, 16:18
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

With respect, I beg to differ. There is an...

With respect, I beg to differ. There is an enormous difference between measuring, let alone calculating, the flow well downstream of the wing with all the attendant uncertainties and random...
Forum: Tech Log
3rd Dec 2012, 15:34
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

That's where I got to also, but it is less than...

That's where I got to also, but it is less than helpful isn't it :D



I flirted with that idea, but the problem is that the measured data shows that neither the upper nor lower TE static...
Forum: Tech Log
3rd Dec 2012, 14:42
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

No, they are not always in ground effect. In free...

No, they are not always in ground effect. In free air they have the flow pattern of a three dimensional wing with infinite wingspan in free air. Two dimensional wings placed near a ground board have...
Forum: Tech Log
3rd Dec 2012, 13:28
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Well I'm sorry you find them unhelpful, but...

Well I'm sorry you find them unhelpful, but incorrect they certainly are not. The pressure distributions are consistent with measurements on a wing of AR 5.0, so what basis have you for saying that...
Forum: Tech Log
3rd Dec 2012, 12:18
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Hazlenuts I think perhaps we are talking at...

Hazlenuts

I think perhaps we are talking at cross purposes, as you are offering a reason why drag is reduced, and I am seeking a Newtonian explanation of why lift is increased.
As a straight...
Forum: Tech Log
2nd Dec 2012, 21:13
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

You can't think of it quite like that. The flow...

You can't think of it quite like that. The flow under the wing is properly regarded as a stream tube. The 'lower' limit of the tube is a streamline running just above the ground. The upper boundary...
Forum: Tech Log
2nd Dec 2012, 19:02
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Actually the tests were done in 1938 (editorial...

Actually the tests were done in 1938 (editorial correction) but the report was issued in 1946.

Sounds reasonable. We know that in free air the greater the vertical distance below the wing TE the...
Forum: Tech Log
2nd Dec 2012, 18:36
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Lyman You may want to make a note of the...

Lyman

You may want to make a note of the date or something, but here is a first - I am going to agree with you!

NACA measurements (wind tunnel I'm afraid FlightpathOBN) made back in 1938 show...
Forum: Tech Log
17th Nov 2012, 18:06
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

@jt Yes thanks for that John. I was OK with...

@jt

Yes thanks for that John. I was OK with symbols using copy and paste and Word or similar, but I was trying to do it directly using the fonts available inside PPRuNe edit text function.
Could...
Forum: Tech Log
16th Nov 2012, 14:58
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

@roulishollandais Diolch

@roulishollandais

Diolch
Forum: Tech Log
15th Nov 2012, 07:52
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

@HN39 Hi HN, You are right of course; the...

@HN39
Hi HN,
You are right of course; the picture didn't say how far back and I didn't think it through. Write in haste, repent at leisure. :O
Close up to the wing the downwash will reflect the...
Forum: Tech Log
14th Nov 2012, 21:50
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Just take a look at Flightpath's pictures -...

Just take a look at Flightpath's pictures - especially the one immediately under "The aircraft wake is compressed, and with the combination of the 2 counter-rotating vortices"

That little symbol...
Forum: Tech Log
14th Nov 2012, 20:51
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Flightpath Sorry, I thought that was common...

Flightpath
Sorry, I thought that was common usage - trailing vortices originating at the tips of a wing with no flap or control surface deflection be OK?

BTW, I've just noticed that on your...
Forum: Tech Log
14th Nov 2012, 18:32
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

@FlightpathOBN Nice pictures, but I asked...

@FlightpathOBN

Nice pictures, but I asked for an explanation of how the vortices developed using Newtonian arguments.

So airspeed doesn't come into it?

The A&E paper says:

.
Forum: Tech Log
14th Nov 2012, 09:13
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

In the conclusions of the Anderson/Eberhardt...

In the conclusions of the Anderson/Eberhardt paper that Lyman cites so often the authors say:
I admit I thought (hoped) that professional pilots might be interested in an accurate description of how...
Forum: Tech Log
13th Nov 2012, 17:31
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

As I said at the beginning:

As I said at the beginning:
Forum: Tech Log
13th Nov 2012, 14:43
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

roulishollandais Nice pictures! :ok: But...

roulishollandais
Nice pictures!
:ok:
But they are theoretical evaluations of the flow in a channel and the flow is subject to three (open channel) or four (closed rectangular channel) boundary...
Forum: Tech Log
2nd Nov 2012, 18:35
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

@roulishollandais I'm not sure I know how to...

@roulishollandais

I'm not sure I know how to reply to your question roulis. Could you expand a little what you mean by please.

If I simply said that I see the flow inside the boundary layer as...
Forum: Tech Log
1st Nov 2012, 16:48
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Sorry Lyman, but when you ask "questions" like...

Sorry Lyman, but when you ask "questions" like that my notable patience runs out.
Forum: Tech Log
1st Nov 2012, 16:22
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

I didn't say that the Anderson/Eberhardt paper...

I didn't say that the Anderson/Eberhardt paper was rubbish. I think it simplifies things a little too much and it can be misleading. For example this business that Bernouilli's equation cannot be...
Forum: Tech Log
1st Nov 2012, 07:45
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Brian, I am prepared for that; there is a mental...

Brian, I am prepared for that; there is a mental autoignore list. My intended "audience" was others who might be tempted to believe the rubbish being posted.
Forum: Tech Log
31st Oct 2012, 11:28
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

To judge by recent postings one might assume that...

To judge by recent postings one might assume that any debate on lift generation is done and dusted and that the simple (simplistic?) Newtonian explanation is the only game in town. But the only...
Forum: Tech Log
27th Oct 2012, 12:25
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Quite :ok:

Quite :ok:
Forum: Tech Log
27th Oct 2012, 09:23
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Hi Hazelnuts, Sure it is, but you also...

Hi Hazelnuts,



Sure it is, but you also wrote:


so the area of the affected stream tube is a finite part of an infinite field - doesn't change my view that one cannot quantify mdot ;)
Forum: Tech Log
21st Oct 2012, 21:50
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Italia458 Yes, Bernouilli's equation is, for...

Italia458

Yes, Bernouilli's equation is, for all practical purposes, valid outside the boundary layer - but note ft's comment that strictly speaking you have to define the limits of the boundary...
Forum: Tech Log
21st Oct 2012, 07:10
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

mm43 Wish I could be with you, but I'd...

mm43



Wish I could be with you, but I'd prefer to be further aft and on the windward side with a tiller in my hand ;)
Forum: Tech Log
21st Oct 2012, 06:35
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

He just did :) Abbot & von D is heavy on...

He just did :)

Abbot & von D is heavy on math. I've just located a better article by Arvel Gentry than the one I have been recommending which covers the same ground but without the maths. It...
Forum: Tech Log
20th Oct 2012, 21:10
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

roulishollandais It should have been obvious...

roulishollandais

It should have been obvious from my earlier posting that I wasn't trying to use the pictures to explain lift; merely using their entirely correct definition of a streamline.
...
Forum: Tech Log
20th Oct 2012, 13:28
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Hi HN39 But what about 2d wings (original...

Hi HN39

But what about 2d wings (original point of discussion) or non-elliptic loading (usually the case)? Downwash not uniformly distributed?
Forum: Tech Log
20th Oct 2012, 08:55
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

This discussion has devolved into a debate on...

This discussion has devolved into a debate on what Anderson and Eberhardt’s (A&E) article ‘Understanding Flight' really means. Having read it two or three times now it seems to me that it is a bit...
Forum: Tech Log
27th Jul 2012, 08:33
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Hi Microburst, As you say, it is almost...

Hi Microburst,

As you say, it is almost intuition! I think that in reality everyone will go for an explanation that suits their mind set. For me, a one-time aerodynamicist, I tend to think...
Forum: Tech Log
26th Jul 2012, 15:18
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

We might as well get the numbers right. In one of...

We might as well get the numbers right. In one of the postings in the Concorde thread M2Dude gave some figures from RR. The cruise fuel flow was 9700 lb/hour/engine and the engine thrust was quoted...
Forum: Tech Log
26th Jul 2012, 15:11
Replies: 388
Views: 99,888
Posted By Owain Glyndwr

Ah, I see what you are getting at. It was the use...

Ah, I see what you are getting at. It was the use of " more accelerated" that fooled me - not thinking straight ;) As you say, if you double the airspeed then the mass flow rate over the wing doubles...
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