mitake, again?
 

Hi ya'll,
November Model Aviation has major error?
Check article> "From Ground Up" by Granelli.
This is a series and in first episode description of engine operation wa
very flawed. MA made attempt to correct problem and promised it
would not happen again.
Now notice that this episode decribes fuel supply methods and ALL of it
is incorrect.
Question>what happened, cross check was not made or checker did not
understand the subject better than the author?
Better to not publish than to present misleading data?
Would do well to let editor have your opinion?
Nuff sed?

Hal deBolt AMA 1520

RE: mitake, again?
 

Yes, I've read quie a bit of well intentioned but bad advice in MA. Apparently they are short on reviewers.

RE: mitake, again?
 

Hal,

was the title of this thread, "mitake, again" intentional? :D

or was it [X(]?

RE: mitake, again?
 

Hal:

When I read that first installment on engines, I emailed a significant complaint to the editor, and AMA. Granelli was held up for several issues. They got a number of complaints according to Hunt. In the next issue when he was allowed to continue, I estimate 40% of his text was trying to worm his way out of his hole by saying what he *intended to say the first time* and that many misunderstood his approach. What a crock of feces.
Now, Hal, out of curiosity I suppose I have to read this article. Since reading his first two articles, when I see *Granelli* I just move on as I don't think he knows very much about engines, or models in general.

OTOH, he knows how to snake his way into a place where he can make money like AMA's e magazine SPORT AVIATOR where one can find the introduction signature of:

Sincerely,
Frank Granelli
Sport Aviator Editor

Now that is one big shame, the Blind leading the Blind, more use of AMA's $$ which came from member dues.

Interesting to see if the elite item called AMA Executive Vice President "CHIEF FINANCIAL OFFICER" can/will ever try to explain this. OOPs, there I go again forgetting that the EVP only parrots the PAID OUTSIDE AUDITOR"S report. I often wonder if he can actually figure any of this for himself. [:-]

I used to think that only weathermen were the people that never had to really know anything about anything and could be forever wrong and everyone accepted such. Now another such position has surfaced. Editors for AMA magazines!

RE: mitake, again?
 

Oh great Hal now you make me want to rescue my copy of MA from the trash and read it. Since it might have pasta sauce or coffee grounds on it can you give details where this Granelli character screwed up in the latest article?

RE: mitake, again?
 

Wow------ You mean someone really reads that so called magazine. -Mike

RE: mitake, again?
 

Hi Billygoat,
want to give you the info you asked for, have a couple of times but this
idiot box reemoves it. Will try in 3 segements and see if that works.
1,,,Granelli states the size of the fuel tank relates to the size of the engine and gives the so called matchs.
Doubt if anyone else ever heard of that?
Tank size is normally determined by space in the craft or length of the
desired engine run?
Wonder is if he knows that a .20 engine ran and flew for many hours with a one gallon tank?
This man's writing is supposed to be reviewed by an expert before publication, have to wonder who the expert is?
There wil be two more replies, OK?

Hal [email protected]

RE: mitake, again?
 

Hi Billygoat,
want to give you the info you asked for, have a couple of times but this
idiot box reemoves it. Will try in 3 segements and see if that works.
1,,,Granelli states the size of the fuel tank relates to the size of the engine and gives the so called matchs.
Doubt if anyone else ever heard of that?
Tank size is normally determined by space in the craft or length of the
desired engine run?
Wonder is if he knows that a .20 engine ran and flew for many hours with a one gallon tank?
This man's writing is supposed to be reviewed by an expert before publication, have to wonder who the expert is?
There wil be two more replies, OK?

Hal [email protected]

RE: mitake, again?
 

I can't blame you for thinking that nobody reads MA. That is certainly the impression you'd get from hanging around RCU. But, as I frequently remind folks, do not confuse the Internet with reality. For a glimpse of what the real world is like (you won't like it), check out the AMA member survey on their web site. You'll see that not only do most AMA members read every word of MA, but they save every copy and refer back to them an average of 5 times a year!

RE: mitake, again?
 

It seems like the AMA and Model Aviation is a closed shop. With 150,000 or so AMA members they are reluctant (nice word for flatly refuse) to address such issues with volunteers from the membership. They easily could have a 100 or so recognized experts in the hobby that the could e-mail the text to for review with strict time limits so that publication dates are not jeopardized. I would gladly be one of the reviewers for battery related articles, any other volunteers so we don't hear, !QUOT!Volunteers never volunteer for these things!QUOT!? Sometimes you have to let people know that volunteer efforts are welcome and what is needed. I recall the great difficulty Bill Lee in D-VIII had in getting them to accept his great membership verification program. Lets hope that Mathewson, when elected President, will begin to harvest the talent available from the membership pool and make the AMA all it can be.

(copy to Bob Hunt, Aeromodeling Editor, [email protected])

RE: mitake, again?
 

Hi Billygoat,
Back again>
2...it is stated that the fuel system is adversely effected in flight by gravity
and centrufigal force. Theroritically one might think that but often what is
seen or happens defies therory?
If one competes in pattern there is constant practise during which craft assumes many different attitudes. The pilot is very aware of power throughout such flights.
Perhaps others can say so also> in the thousands of pattern flights I have made never has a power difference of any sort been seen, when
the engine has been properly set before flight. This with and without the
use of a pressure fuel system (before mufflers and exhaust pressure?
This man supposedly has long flight experience and is a flight instructor,
wonder is what has led him to believe what he states?

Hal

RE: mitake, again?
 

Hi Billygoat.
Back a 3rd time with this 3rd portion, will keep it short and hope it does
not get cut.You have more unanswered questions, just ask.
3...Perrtains to statement>As head pressure drops the fuel forces still
decline since the engine does not apply more pressure just because the
fuel level is getting lower.
Two factors in that wording> "head presure' is the force created in a tank by the amount of fuel ABOVE the fuel outlet. This force diminishs as the
fuel is used, force disappears when fuel level is below the outlet.
Pressure is applied in the tank by the engine.
The tank has an inlet and an outlet, thus is sealed otherwise.
Pressure is presented in the tank which acts as a pump forcing fuel through the outlet.
Amount of pressure supplied by the engine varies with rpm but it is always there. The force is constant at any given rpm, at that speed it
does not increase or diminish.
So in effect physically the pressure is "compressed " air (lets call it) which
the engine feeds the tank. The tank being sealed the compression remains
at what ever level it is put in at. As fuel diminishs the vacancy is filled with
more compressed air and it still is at the same force level.
Effect is that a pressure fuel system, as a pump would do, supplies fuel to
the engine at a constant rate until the tank is empty.
Examples where such is most important would be C/L speed and R/C pylon where max power is required constantly.
Will close and hope!!!

Hal

RE: mitake, again?
 

Hey Mike in DC I really don't belive whats on the internet. I base my thoughts on M.A. by checking with fellow R/C"ers I have spoke with over 20 years of flying R/C. As far as the reader survey you spoke of, if the percent of people who responed to the survey is the same as the ones who voted in the last election it repersents a small fraction of the AMA membership. I just feel the money could be better spent. -Mike

RE: mitake, again?
 

With all due respect (and there IS a LOT of that!), your explanation is just as misleading/wrong as the one in MA.

For ease of understanding, consider a steady state condition: engine running at a constant speed, model flying at a constant speed and configuration. I.e., no maneuvers, etc.

In the beginning, the tank is full, and the "head pressure" is as you described: the pressure of the weight of the fuel above the needle valve position where "above" is the direction of the vector sum of forces acting on the system. (For a model flying straight and level, the force is just gravity. For a CL model, it's the vector sum of gravity plus centri..) As the fuel is withdrawn from the tank by the engine, the "head pressure" drops, and becomes zero when the fuel level reaches the same level as the needle valve. And becomes a negative value when the fuel level is below the needle valve.

If you can imagine this as a graph, pressure as a function of amount of fuel in the tank, it is a straight line.

If there was NO muffler (whatever) pressure being supplied, we would still have atmospheric pressure in the tank. Adding a constant amount of pressure simply translates the "pressure head" upward by the amount of the muffler pressure supplied. There is STILL a pressure transition as the fuel is withdrawn!

The advantages of using a pressure system are very definitely there, but eliminating the "pressure head" is NOT one of them!

This can be controlled by tank design, it is pretty simple physics.

Regards,

Bill Lee

RE: mitake, again?
 

I've been involved with this hobby for about 20 years and have had time to notice one thing as being a constant; every time some guy gets courageous enough to stick his neck out and do an article on either engine theory or operation, his work will get criticized and ridiculed. I don't think any other category of tech writing brings this kind of reaction out as much, must be some psychology to that? I don't absolutely agree with his engine to tank size parameters, I think they were too liberal. Like most of us, Mr GRANELLI probably learned most of what he knows from other people [competitors]and from what he has learned through personal experience. I am willing to bet that if a newcomer to this hobby was to take his advice, no harm would come from it, and the bottom line would be bone dry tanks at the end of a hard run.

RE: mitake, again?
 

Hi Bill.
In reply would suggest that I am not wrong as indicated, perhaps not
thorugh or complete enough with the description.
Obviously I did not consider atmospheric pressure but is that really a consideration when you understand that something suspended sees this
pressure on ALL sides?
We generally see atmospheric pressure in relation to earth or the planet
but must realise it is a force created by the weight of the armosphere. At sea level about 15 lbs per cubic foot? If you raise a bit above earth the
pressure might be 10 lbs but what ever the amount the same force effects anything suspended in it on all sides.
Thus in the case of a fuel supply in flight the only effect is to condense
the liquid?
Fuel flow at the needle valve (Will cover that with another post) Darn
idiot box will shut this off and lose the effort, OK>?

Hal [email protected]

RE: mitake, again?
 

Whatever....

Bottom line: muffler pressure will NOT eliminate the "head pressure" inherent in a fuel system.

Regards,

Bill Lee

RE: mitake, again?
 

Hi Bill,
This PC problem is endless, will have to make this much briefer than
would like to have it, maybe go to two sessions?
First pressure applied to the fuel has no effect on the head pressure for
sure. only action is to increase TOTAL pressure seen.
Fuel flow> must be known that effectively an engine is a mechanical pump whose pumping action draws fuel and air through the carburetor
where a proper 15:1 air-fuel mixture is established that fires in the combustion chamber resulting in producing power.
Will continue on another post. OK?

Hal

RE: mitake, again?
 

Hi Bill,
Back and this is sumpin' else?
The amount of fuel mixture the engine desires is regulated by the amount
of suction at the carburetor. So it is the suction which creates the correct
fuel flow.
With a plain fuel supply this action is automatic with the mixture being attained by adjusting the amount of fuel flow with the needle valve.
The engine's correct operation is with this fuel flow so it must be mintained.
When pressure is applied to the fuel supply this increases the possible
fuel flow at the carburetor intake,. the amount of air intake remains same.
So, to create proper mixture the needed fuel flow is adjusted via the needle valve. Actually the needle is closed an amount to suit the pressure
present.
Effectively all the fuel supply and flow must do is to be sure fuel is available in the needed amount for the suction to draw from at the carb
inlet.
Will cut short and hope!~

Hal [email protected]

RE: mitake, again?
 

Hi Bill,
Back and this is sumpin' else?
The amount of fuel mixture the engine desires is regulated by the amount
of suction at the carburetor. So it is the suction which creates the correct
fuel flow.
With a plain fuel supply this action is automatic with the mixture being attained by adjusting the amount of fuel flow with the needle valve.
The engine's correct operation is with this fuel flow so it must be mintained.
When pressure is applied to the fuel supply this increases the possible
fuel flow at the carburetor intake,. the amount of air intake remains same.
So, to create proper mixture the needed fuel flow is adjusted via the needle valve. Actually the needle is closed an amount to suit the pressure
present.
Effectively all the fuel supply and flow must do is to be sure fuel is available in the needed amount for the suction to draw from at the carb
inlet.
Will cut short and hope!~

Hal [email protected]

RE: mitake, again?
 

Hi ya'll,
I am quite ashamed of the manner required to reply to Bill's input.
very embrassing?
I have endeavored to correct the problem to no avail.
I am with Juno internnet service and the problem is that when writing
a reply, after about 5 minutes I am cut off the web and told to restart
if desired.
Would be greatly appreciated if anyone knows a cure for this, if so
could you tell me via Email? Many thanks!
Best wishes,

Hal [email protected]

RE: mitake, again?
 

Hal-

A sure and simple cure to the problem you are having with losing the connection before you are done composing is to do it offline. Use Notepad or Wordpad, for example, to write your reply, then go online and Copy and Paste it into the Reply to Message box.

Abel

RE: mitake, again?
 

I hate it when that happens... but alas ego or pride is a common problem...only a few men rise above the norm.

RE: mitake, again?
 

Yes, you very well probably see that from your position in the crowd.
Personally I am more aligned with ol' General LeMay back when he said, "Don't tell me your problems, just show me the results."

RE: mitake, again?
 

Thanks Hoss

Thanks for your insightful observation. Of course my position and OUTLOOK may very well be from the crowd but it is much better than INSIGHT from a crowded position!:D


Reason for edit: totally uncalled for picture!