RE: Suggestion for moderators

RE: Suggestion for moderators
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RE: Suggestion for moderators - 11/7/2005 3:58:42 AM

Carlos G

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Joined: 12/6/2002
From: Walla Walla, WA, USA
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Hi Dick

I have found that aerodynamics has very little to do with getting model and full size aircraft to fly. Its Money that makes 'em fly, pure and simple.

Carlos G
AKA
The BaronVonEvil

(in reply to dick Hanson)

Post #: 251

RE: Suggestion for moderators - 12/30/2005 6:58:53 PM

jamieduff1981

Posts: 131
Joined: 12/29/2005
From: ELLONScotland, UNITED KINGDOM
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Fairly new on RC Universe, but I have a formal education in aerodynamics, a practical education in aerodynamics and full size aircraft building, maintenance and piloting, as well as a long running education in flying models.

I've been cringing reading some people's claims on this thread. Some people are right, others are right but irrelevant, others have a half baked understanding and hence insult the theories proclaiming them to be useless whilst others still talk total nonsense.

I'd like to put some perspective on things.

Almost any aircraft that's been built was designed by:

Listing the NEEDS
Listing the WOULD LIKES
Doing some calcs
Reviewing the numbers with an experienced mind
Revising the calcs
Turn the calculated values into drawings (areas, moments etc etc etc)
Review and revise. Refer to NEEDS and WOULD LIKES
Fiddle the drawings to improve the visual appeal.
Prove the drawings by testing a model
Review results
Revise Calcs
Modify Drawings
Build a prototype
Assess the flying characteristics
Review findings and compare with calcs
Revise as neccessary
Produce

Anyone who thinks building an aircraft is only about TLAR is a fool. TLAR is only safe to use by the experienced. What looks about right on any particular airframe to one person may look distinctly wrong to another person with more experience.

No-one in the right mind builds an aircraft on looks then sets about finding out it's capabilities. Aircraft are built for function first, form second. There was little room for TLAR and trial and error on a project such as the B-2 or A380. These were designed with maths, confirmed with models then expected not only to fly, but to perform as per the numbers.

Anyone who doesn't understand aerodynamics, I appeal to you NOT to proclaim them as worthless.

Terminology - some people advertise their ignorance by using the wrong words to express their thoughts on engineering matters. If you don't know the "fancy words", then you don't know what you're talking about - SIMPLE!

GRIPE OVER

Of course, there comes a point when calculating becomes trivial with model aircraft because we still fly in full size air molecules. Models of full size aircraft can be tested in higher pressure air to compensate for differences partially, but there remains a need to confirm findings and expectations with a test flight programme. In addition, models are often extremely crude aerodynamically compared to full size aircraft (exposed servos under wings and all that really screws up the slip stream)

I back up the previously stated comments that there is a distinction between flying and flying well. Whilst some modellers may feel proud that they can handle an unstable model, others may simply view them as crap builders. The modelling holy grail lies somewhere between building a perfectly stable aircraft that happily flies without pilot intervention, whilst retaining the ability to be manouvered as the pilot wants.

May I state that "extreme flying" as some people call it (3D????) isn't actually flying at all. Neither are the full-size aerobatic counterparts. It's simply phenominal power and large control surfaces influenced by propellor slipstream. Nothing more. I'm not saying it doesn't require great skill, it certainly does, but it's not aerodynamic flying in the classical sense.

(in reply to Carlos G)

Post #: 252

RE: Suggestion for moderators - 12/30/2005 7:08:16 PM

rogerswin

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From: Placentia, CA, USA
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((comments retracted))

Roger

< Message edited by rogerswin -- 12/30/2005 8:09:33 PM >

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Post #: 253

RE: basic aerodynamics - 12/30/2005 7:39:12 PM

mesae

Posts: 568
Joined: 12/16/2002
From: Edmond, OK, USA
Status: offline

quote:

ORIGINAL: dick Hanson

OK here is a setup - remember you drop the wing loading to zip -then add 2-1 power capabilities -the result is a model which will fly at about any attitude.
the SPEED is so low and the angles of flight are so high that flight is basically thrust with guidance by the ailerons etc..
...

I'm sorry, I know this post has been out there a while but I just have to say something here.

If the wing loading is zip, then the weight is zip. Then how do you calculate a 2:1 power to weight ratio? An engine capable of ANY thrust would result in an INFINITE power to weight ratio, which is meaningless. The reference to a 2:1 power to weight ratio on a weighless aircraft is nonsense.

_____________________________

"The purpose of time is to prevent everything from happening all at once."

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Post #: 254

RE: basic aerodynamics - 12/30/2005 7:49:05 PM

jamieduff1981

Posts: 131
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From: ELLONScotland, UNITED KINGDOM
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Have to agree - the zero wing loading concept is impossible and totally trivial. It cannot be imagined because it doesn't make sense. The assumptions contradict one another.

As to having fun, well great. I for one care about aerodynamics, as do others or else this forum wouldn't exist.

If a question is asked, it deserves to be answered fully and correctly.

When I see things written which I know to be inaccurate or only partially true then I feel a responsibility to other readers to set the record straight.

(in reply to mesae)

Post #: 255

RE: Suggestion for moderators - 12/30/2005 8:00:45 PM

mesae

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From: Edmond, OK, USA
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quote:

ORIGINAL: dick Hanson

...
If it weighs zero or almost zero and has very low wing loading - you can take extreme liberties with CG- we have been back past 50% of MAC- and -they are still flyable - you gotta watch em -but they still fly
enough power to overcome weight -easy one -it will fly no matter how badly the designed is bungled.

..

First sentence: You are still stating an approximate aft CG limit. All airplanes have their limits for acceptable controllability. A 50% limit means that CG very definitely DOES matter.

Second sentence: If the CG is so far back that the pitch oscillations are too large and/or rapid for a given pilot to correct, it will be a very short flight, even with a 100:1 power to weight ratio.

I think you have destroyed the original purpose of this thread.

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Post #: 256

RE: basic aerodynamics - 12/30/2005 8:01:47 PM

mesae

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From: Edmond, OK, USA
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You GO Jamie!

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Post #: 257

RE: Suggestion for moderators - 12/31/2005 5:06:50 PM

dick Hanson

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From: slc, UT, USA
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Nice to see that you boys read !
The whole idea of my "uninformed bits of worthless formula" was to see who actually did fly and evaluate the capabilities of extremely low weight -high power models
apparantly you guys are not into that type of thing
The stark reality of the "non flying 3D models tho --is that --- they do fly -
The rules YOU may choose to believe are set in stone - may be OK for you.
However ; when the rule says one thing --and the results say another -- it does not take long to figure out that something is amiss.
I do understand the so called "classical " aerodynamics . And I do use them -all the time
To deny that other types of flight are simple abberations -is simply a flawed response.
They work and if you can not learn from them - it's your loss- not mine.

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(in reply to mesae)

Post #: 258

RE: Suggestion for moderators - 1/1/2006 12:06:24 AM

jamieduff1981

Posts: 131
Joined: 12/29/2005
From: ELLONScotland, UNITED KINGDOM
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That's exactly it though, high power, light weight 3D flying is simply thrust vectoring. Nothing more.

There's nothing else to understand. I don't think I'm missing anything as I already understand what physics allow that aircraft to perform those manouvers.

If you're only airborne because of sheer power and control authority then no, I don't suppose CofG really does matter quite that much.

(in reply to dick Hanson)

Post #: 259

RE: Suggestion for moderators - 1/1/2006 1:40:13 AM

mesae

Posts: 568
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From: Edmond, OK, USA
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quote:

ORIGINAL: dick Hanson

Nice to see that you boys read !
The whole idea of my "uninformed bits of worthless formula" was to see who actually did fly and evaluate the capabilities of extremely low weight -high power models
apparantly you guys are not into that type of thing
The stark reality of the "non flying 3D models tho --is that --- they do fly -
The rules YOU may choose to believe are set in stone - may be OK for you.
However ; when the rule says one thing --and the results say another -- it does not take long to figure out that something is amiss.
I do understand the so called "classical " aerodynamics . And I do use them -all the time
To deny that other types of flight are simple abberations -is simply a flawed response.
They work and if you can not learn from them - it's your loss- not mine.

An odd way to find out who flies a certain type of aircraft: Make untrue statements about physics.

"To deny that other types of flight are simple abberations -is simply a flawed response." I'm trying to be careful here but it looks like you are trying to say that people should acknowledge that other types of flight are abberations. Is that what you meant to write?

No flight is an aberration. If it doesn't behave the way we expect it to, it's because we don't fully understand it. There is no escaping physics. If it flies the way you like, then so be it. It's not violating any laws, it's complying with them all. You don't have to understand them to have fun, but please read on.

Just because you can modify or design a foamy and it flies, or flies better, doesn't mean you know more than an engineer about aerodynamics, which you seem to be implying (Please correct me if I have misread). Anyone can do that, without understanding the physics thereof. I take no exception to anyone experimenting with foamies (or whatever) using trial and error or eschewing math and physics. I do take exception with people making untrue statements, and claiming to disdain physical laws that have been established for decades, and passing that off as "wisdom" for newbies.

If you understood "classical" aerodynamics, it seems unlikely you would have made reference to a weightless airplane possessing a 2:1 thrust to weight ratio.

I don't understand what rules you feel are being violated by lightweight planes. Their behavior can be explained by well understood principles, which is supported by reasonably good aerodynamic computer (mathematical) models in RC simulators available right now, as one example.

You also seem to be drawing unwarranted conclusions about what we are into or not, or what we learn or not, simply because some of us point out that you have made untrue statements about aerodynamics. I fly foamies too. I have also professionally flown (and helped modify with engineers; I'm not an engineer but I've studied it recreationally) very underpowered 900 lb UAVs with 27 foot wingspans, and a 210 lb UAV with an 18' wingspan that was powerered by a 120 CC engine, and many full-scale airplanes.

It would be good if more people could just admit when they have posted erroneous information.

< Message edited by mesae -- 1/1/2006 1:42:24 AM >

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"The purpose of time is to prevent everything from happening all at once."

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Post #: 260

RE: Suggestion for moderators - 1/1/2006 2:27:24 AM

dick Hanson

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From: slc, UT, USA
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Looks like I wounded your ego - sorry about that -
You did however take literally what I said about zero weight - and cg- 2-1 thrust etc..

I was simply trying to explain a concept; "it the weight is practically zero ,the cg really can be abused thru the use of power to correct attitude /direction/speed."
I distain laws of physics?
How do you know that?
My comment about abberations Read it again .
I was referring to the comment that "extreme flying is not flying in the classical sense! (made in early post by Master Duff--)
Aerodynamic flying--- what does that mean?
If it flys -it flies
If it is a craft which is a compromise made to do a specific task ( a 747) or a toy which flits wildly about for entertainment - what is the difference ?
both fly
Oh here is a project that a friend is working on - I did some of the structural work -and have flown it -- probably not worth mentioning in this column -anyway --

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< Message edited by dick Hanson -- 1/1/2006 3:16:44 AM >

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Post #: 261

RE: Suggestion for moderators - 1/1/2006 2:23:00 PM

mesae

Posts: 568
Joined: 12/16/2002
From: Edmond, OK, USA
Status: offline

quote:

ORIGINAL: dick Hanson

Looks like I wounded your ego - sorry about that -
You did however take literally what I said about zero weight - and cg- 2-1 thrust etc..

I was simply trying to explain a concept; "it the weight is practically zero ,the cg really can be abused thru the use of power to correct attitude /direction/speed."
I distain laws of physics?
How do you know that?
My comment about abberations Read it again .
I was referring to the comment that "extreme flying is not flying in the classical sense! (made in early post by Master Duff--)
Aerodynamic flying--- what does that mean?
If it flys -it flies
If it is a craft which is a compromise made to do a specific task ( a 747) or a toy which flits wildly about for entertainment - what is the difference ?
both fly
Oh here is a project that a friend is working on - I did some of the structural work -and have flown it -- probably not worth mentioning in this column -anyway --

My ego??? That was a bit presumptuous

As far as taking literally the zero weight statement, you did write "zip", which to me means zero. You then stated a mathematical relationship between power (actually thrust) and weight that resulted in a "divide by zero" situation. Since this is a thread on aerodynamics, it pays to word one's statements carefully.

The above sentence about CG is a lot closer to reasonable than saying it doesn't matter for a light airplane. What might be even more accurate might be to say something
like, "As a given airplane lightens, the usable CG range increases", or something like that.

I read and re-read your sentence about aberrations. Still doesn't make sense. It doesn't read anything like your more reasonable and obvious statement above.

Despite the differences in the way some of us word things sometimes, it's likely that we agree on more points than we disagree on.

The tube is interesting. What is it's intended purpose?

_____________________________

"The purpose of time is to prevent everything from happening all at once."

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Post #: 262

RE: Suggestion for moderators - 1/1/2006 4:50:11 PM

dick Hanson

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Joined: 12/12/2001
From: slc, UT, USA
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It increases lateral area -just another way of doing this
effectively the model -in hesitation rolls or very slow rolling agenda--will have more usable lift--in this area.
Please - don't read all this aerodynamic BS so literally
the concept is what counts
One can formulate till the cows come home
means zip
Unless you actually DO something and test it-- in real world -all the rest of it is simply up ending mouse turds.
frittering away time.
I don't have a formal education--and I have the patents to prove it .

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Libby

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Post #: 263

RE: Suggestion for moderators - 1/1/2006 5:54:57 PM

mesae

Posts: 568
Joined: 12/16/2002
From: Edmond, OK, USA
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I don't doubt your accomplishments, trophies or that you might be a good stick. I'm sure you are creative and resourceful.

Some of your statements might be interpreted as disdain for those who choose to use mathematics to model the behavior of their as-yet unbuilt or unmodified craft, before even taking knife to wood. Whether this is a waste of time or not depends on many factors. It can be argued strongly that it actually saves a lot of time and expense by eliminating untenable ideas based on well-known principles. No sense trying ideas that are very unlikely to work. Of course, what's the point in designing if you are not going to eventually build and test? So it's all good. The geeks can calculate