Well it seems like a whole bunch of hair splitting about what the problem with the article is. Can someone tell me if this has anything to do with the fuel mixture getting leaner as the tank empties because if I understand what Hal is saying it doesn't change at all.

As for Horace finding fault with something in MA, big shockeroo that is. For Christmas we should all chip in for a new fine tooth comb so Horace can continue to read MA in the manner to which he is accustomed.

I think what Hal is saying is that the Head pressure is pretty insignificant compared to the tank pressurization.
Fuel (Methanol) is about .031 lb/in^3. It takes 3" depth of this stuff to get 0.1 psi pressure. Now, I haven't put a gauge on my machine, but I would bet that exhaust pressure on my Magnum .46 exceeds that by some fairly large amount.
Thus, the head pressure is insignificant in an exhaust pressurized system

Well that makes a lot more sense and you fit it into one post. I guess we can at least all agree that MA's articles pretty much suck.

I'd like to see Red or Hal or Horace published in any of the rags. They have a lot of knowledge to pass on and should submit an article or two to RCM,MAN,FlyRC if AMA isn't open to new writers.

I know Red and Hal have BTDT many times, dunno about Horrace - might have happened before my generation.

Abel

You forgot R/C Report - I'm there occasionally, in fact this month (November) has my review of the Sommer Miniron 5 port battery maintenance system. When I write a product review I like to see it in print before the product goes out of production.[>:]

Over the years, I've seen several articles on using large capacity tanks to get enormous endurance from small engines, even one on a control line plane. Every one of the articles I've read, the large (several quarts to over a gallon) tank is pressurized by some method, I believe Bill Winter used a couple large sized Walker balloon tanks, and feeds a smaller header tank by means of some type of control valve, usually using a float in the header. Even one of our club members was geting 5 to 6 hours on a Kadet Sr. this way. The engine just wouldn't run reliably for more than a short period of time if fed from the large tank directly.

Hi Basinbum and all,
Subjects can get nitty gritty?
Fuel flow leaning as tank empties.>sure does but a properly adjusted
engine before flight compensates for that.
Know> two factors cause fuel flow to reduce (lean?) in flight from what
it initially was, however happily the change is not great. (fuel amount)
1...when a craft is in level flight or most of the flight the inertia built up
allows the propeller to "unbload". With a reduced load engine rpm increases and that demands more fuel. 2...As fuel tank empties the head pressure decreases which effects the
amount (pressure) of the fuel at the carburetor inlet. With a properly mounted tank this pressure never becomes negative.
In as much as the engine's suction creates the demand for fuel (not the
fuel system) as long as there is fuel at the inlet the engine is happy?
In essance we compensate for these things when we initially set the
mixture. Remember the advice> when setting the neddle bring the engine to full rpm and then back off 2 to 3 hundred rpm? This compensates, OK?
Nuff sed? Good luck,

Hal [email protected]

Hi 50+,
Good o have your insite.
If one has a very oversized fuel tank (gallon?) it is obviously far from the
norm and one could expect needed special attention?
A good start is to have the tank outlet on same level as carburetor inlet.
thus fuel as used always has gravity pressure which is constant and a constantly decreasing head pressure.
This arrangement has been made useful by having the large tank feed
into a small one at carb inlet level. Small auxillary tank is equipped with
a shut off valve which closes when aux tank is full.
Worked fine on record attempts but such a large tank is far from norm?
Experience suggests any engine which runs well with normal tank positions will also do so with larger fuel tanks
Of course as is common knowledge any form of pressure is an advantage in assuring there will always be fuel at the carburetor inlet for
the engine to draw from.
Nuff sed, OK?

Hal [email protected]

Hi ya'll,
First Basinbum> thanks much and check 1/005 M.A.N. for another effort.

Latest report on fuel supply description errors.
Have checked with engine guru Dave Gierke who says my description is correct and the Nov Model Aviation "From Ground Up" article is in error.
Bob Hunt suggested he would review the findings.
We asked for a yes or no concerning any action that might be taken.
To date, 11/4/004 there has been no reply.,
It seems, very often this editor's actions are difficult to understand?
Why is there need to be frustrated?

Hal deBolt

Hal,
You have been around long enough to recognize 'politically correct entries to MA' when you read them. SOMEONE wants MA to be full of used hay, and so it is. Some of us get frustrated because MA SHOULD represent US to the world and instead it seems to be full of that used hay. While that may not be exactly a bad thing for the political issues, for technical information that appears to spell the death of our organization. At least to those of us who still care, and I KNOW you do.