Header Tanks
ErgoMan
one, and I quote " Adds some needed flight time, too" While this is
essentially true, anyone flying into the header tank fuel is asking for
trouble. I do not consider my header tank a extra fuel cell that will give
me more flight time.
And I need to add one other thing. If you are a pilot that is doing extreme
3d as well as arobatics, the header tank will also keep you from sucking air
into your carbarator which helps maintain fuel pressure as well.
--
ErgoMan
98 CR250r
Remove NOSPAM to reply via email
bmwebb wrote in message <36CCDC36...@usa.spamorama.net>...
>The biggest advantage I can figure is that it helps to maintain a
>constant fuel pressure (?) for the engine. As the fuel in the main tank
>gets lower with use, the fuel draw for the engine goes from a higher
>pressure (full tank) to a lower pressure (empty tasnk). The header tanks
>acts as a damper between the main tank and the carb, helping to maintain
>a more consistent fuel draw pressure to the carb. This evens out your
>mixture setting at the needle. Adds some needed flight time, too. I put
>one on mine, and it does work.
>
>Best I could do,
>Bradley
>
>Gary Grant wrote:
>
>> Some of us were discussing at the local hobby store what advantages a
>> header tank provides on a heli and how it works. Many theories were
>> presented but not many agreements. Any liquid dynamics experts out
>> there?
>
Gary Grant
bmwebb
constant fuel pressure (?) for the engine. As the fuel in the main tank
gets lower with use, the fuel draw for the engine goes from a higher
pressure (full tank) to a lower pressure (empty tasnk). The header tanks
acts as a damper between the main tank and the carb, helping to maintain
a more consistent fuel draw pressure to the carb. This evens out your
mixture setting at the needle. Adds some needed flight time, too. I put
one on mine, and it does work.
Best I could do,
Bradley
Czeslaw Dabrowski
> You are basically right about all the below statements with the exception
of
> one, and I quote " Adds some needed flight time, too" While this is
> essentially true, anyone flying into the header tank fuel is asking for
> trouble. I do not consider my header tank a extra fuel cell that will
give
> me more flight time.
>
> And I need to add one other thing. If you are a pilot that is doing
extreme
> 3d as well as arobatics, the header tank will also keep you from sucking
air
> into your carbarator which helps maintain fuel pressure as well.
Air in the carburettor can kill the engine and not only in extreme 3D
aerobatics but in ordinary loop or roll when the clunk is exposed to the
air in the tank. It can happened easly, when the silicon tubing to the
clunk is stiff, heli is in upside down position. I think this is the main
reason for the header tank, to supply the fuel regardles of the heli
position.
As for the fuel pressure, the header tank is only prolonged fuel tubing.
The pressure is still mainteined by exhaust presure. (IMHO)
Czeslaw
WILLB33345
does this becuase the header tank is always full up and there is no room inside
for it to foam and it will always trap the air bubbles preventing them from
going into your engine. I have tried my heli's with an without them and
personally I have seen no major improvements.
Will Beasley,
in wet and windy Oxford, UK.
t...@sourcecode-inc.com
I think this is one is fairly straight forward...
"Nature abhors a vacuum".
regards,
tob
In article <36CC5B99...@flash.net>,
gkg...@flash.net wrote:
> Some of us were discussing at the local hobby store what advantages a
> header tank provides on a heli and how it works. Many theories were
> presented but not many agreements. Any liquid dynamics experts out
> there?
>
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
bruc...@my-dejanews.com
gkg...@flash.net wrote:
> Some of us were discussing at the local hobby store what advantages a
> header tank provides on a heli and how it works. Many theories were
> presented but not many agreements. Any liquid dynamics experts out
> there?
>
The engine draws from the header tank and the header tank draws from the main
tank. This keeps the header tank full and eliminates any chance for air
pockets that could make make the engine cough. And yes it does add flying
time. Just don't do any aerobatics when you get down to the header tank.
bmwebb
header tank, I do run my main down to near zero fuel. I was too scared of that
before. So I do get some more flt time. As someone else in the NG said, I just
get comfy and feelin' good, then have to land for gas. Kinda' sucks.
As for the air in the carb, it does provide a buffer from that. But I still get
air in the header tank. As I fly around, the header tank gets about half full of
air. As I think about it, I may want to reverse my header tank so the clunk lays
forward, so I don't "suck a bubble" with the nose down in FFF. Do you guys have
this happen with the tank?
Bradley
ErgoMan wrote:
> You are basically right about all the below statements with the exception of
> one, and I quote " Adds some needed flight time, too" While this is
> essentially true, anyone flying into the header tank fuel is asking for
> trouble. I do not consider my header tank a extra fuel cell that will give
> me more flight time.
>
> And I need to add one other thing. If you are a pilot that is doing extreme
> 3d as well as arobatics, the header tank will also keep you from sucking air
> into your carbarator which helps maintain fuel pressure as well.
>
> --
> ErgoMan
> 98 CR250r
> Remove NOSPAM to reply via email
>
> bmwebb wrote in message <36CCDC36...@usa.spamorama.net>...
> >The biggest advantage I can figure is that it helps to maintain a
> >constant fuel pressure (?) for the engine. As the fuel in the main tank
> >gets lower with use, the fuel draw for the engine goes from a higher
> >pressure (full tank) to a lower pressure (empty tasnk). The header tanks
> >acts as a damper between the main tank and the carb, helping to maintain
> >a more consistent fuel draw pressure to the carb. This evens out your
> >mixture setting at the needle. Adds some needed flight time, too. I put
> >one on mine, and it does work.
> >
> >Best I could do,
> >Bradley
> >
bmwebb
in it. By the time my main is empty, the header is about half full. I could see
this allowing foaming and air int o the engine. Maybe I don't have something set up
right.
Granted, I don't really notice too much of a difference with one as opposed to
without one. But the cost in weight and complexity is small compared to it's main
advantages - a couple more ounces of fuel to fly with, and possibly a more even
mixture.
Bradley
Brett
MArmitstead
>
> Headers were also designed to eliminate any air bubbles and fuel foaming. It
> does this becuase the header tank is always full up and there is no room inside
> for it to foam and it will always trap the air bubbles preventing them from
> going into your engine. I have tried my heli's with an without them and
> personally I have seen no major improvements.
Will,
I have also not seen any major improvements with a header tank
either,not as far as maintaining a constant mixture as the main tank
empties goes anyway,someone has already stated that it just acts as a
wider section in the fuel feed,to "hopefully" trap bubbles in the feed
to the carb
Probably best system for the clunk (on the header) is to mount a
solid pipe for the feed to the carb that extends half way down the tank
and mount the tank upright,i used the small sullivan slant tanks.This
allows a good fuel feed wether upright,inverted or on it's side,but the
tank is not always full to the brim with this setup.
The header tank must be soft mounted too or the anti foaming
advantage the small header has over the main tank can be lost.
Martin
t...@sourcecode-inc.com
I would make sure that all of the tubing connections, etc. are air-tight...it
could also be that the "klunk" line in the main tank is either too long and so
gets stuck OR too short and so allows air way too soon....
regards,
tob
In article <36CD85C9...@usa.nospam.net>,
bmwebb <bmw...@usa.nospam.net> wrote:
> Well, I wish I could say mine does this. As I fly around, the header tank gets
air
> in it. By the time my main is empty, the header is about half full. I could
see
> this allowing foaming and air int o the engine. Maybe I don't have something
set up
> right.
>
> Granted, I don't really notice too much of a difference with one as opposed to
> without one. But the cost in weight and complexity is small compared to it's
main
> advantages - a couple more ounces of fuel to fly with, and possibly a more
even
> mixture.
>
> Bradley
>
> WILLB33345 wrote:
>
> > Headers were also designed to eliminate any air bubbles and fuel foaming. It
> > does this becuase the header tank is always full up and there is no room
inside
> > for it to foam and it will always trap the air bubbles preventing them from
> > going into your engine. I have tried my heli's with an without them and
> > personally I have seen no major improvements.
> >
> > Will Beasley,
> > in wet and windy Oxford, UK.
>
>
-----------== Posted via Deja News, The Discussion Network ==----------
WILLB33345
the header from the main tank and due to the wonderful laws of physics/whatever
it is always full up. The fuel then goes from the header to the carb. The
design is used so that the header tank is constantly full up with fuel,
therefore it elimintaes fuel foaming and will catch air bubbles that would
normally go into your carb and make your engine fart in flight or in the worst
possible scenario a flame out in flight.
Podnboom
also secure the main tank with double sided foam tape. Ofcourse, all of this is
in addition to getting start shaft run-out below one thousandth, which can take
up the better part of an evening. :-(
Kelly
Mike Phillips
you are pulling in air thru the clunk in the main tank at regular intervals.
Header tanks keep my machines from running lean as the fuel runs out. Big difference
for my piped machines.
The other thing I always do is take a piece of fuel line about 3mm long and install it
over the end of all fuel line ends. I use a pair of needle nose pliers for this. This
keeps the heat and vibration from loosening the fuel lines and causing a lean mixture.
The fuel line then fits very tight for as long as you use it. It also takes away some
of those days when the mixture just won't dial in.
Mike
bmwebb wrote:
> Well, I wish I could say mine does this. As I fly around, the header tank gets air
> in it. By the time my main is empty, the header is about half full. I could see
> this allowing foaming and air int o the engine. Maybe I don't have something set up
> right.
>
> Granted, I don't really notice too much of a difference with one as opposed to
> without one. But the cost in weight and complexity is small compared to it's main
> advantages - a couple more ounces of fuel to fly with, and possibly a more even
> mixture.
>
> Bradley
>
> WILLB33345 wrote:
>
> > Headers were also designed to eliminate any air bubbles and fuel foaming. It
> > does this becuase the header tank is always full up and there is no room inside
> > for it to foam and it will always trap the air bubbles preventing them from
> > going into your engine. I have tried my heli's with an without them and
> > personally I have seen no major improvements.
> >
Elizebeth Burgess
whatever) it will suck air into the engine. I don't see how a header
tank can stay always full, when the cluck sucks air in the main tank.
Won't that just bring air into the header tank? And if that happens, the
fuel can foam in the header tank...what's the point? The only advantages
I see are a few ounces increase in capacity, and perhaps less air into
the engine if the header tank stays mostly-full. I guess my question is,
"is it worth it?"
James
Russ
fluid hydraulics answer has two parts (dynamic/flowing pressure losses
and static pressure loss/gains):
When fuel flows through the system, pressure is lost due to friction.
This depends on the fuel properties (primarily viscosity) and the length
and width of the fuel tubing. More pressure is lost in thin tubing.
For hydraulic purposes the header tank looks like very thick tubing so
less pressure loss. The amount of extra plumbing required to feed the
header tank however out weighs any benefit.
The confusion really starts with the static hydraulics. There is a
simple law of nature that states that the pressure difference between
any two points in our fuel system (while not flowing) is equal to the
density of the fuel times the acceleration of gravity (g) times the
difference in height between the two points. The path that the fuel
takes between point a and b is irrelevant (in static hydraulics), only
the difference in height matters.
Example: If a fuel tank 5cm high is filled to the top the pressure
difference between the top and bottom of the tank would be:
Height x density x gravity = 0.05m * 750kg/m3 * 9.81 m/s2
Pressure = 367.875 Pascals => 0.05 psi
If the carb is inline with the centre of the main tank then there is a
0.025psi of positive pressure trying to push the fuel into the carb when
full. When nearly empty there is a negative pressure of 0.025 psi
trying to suck the fuel from the carb during level flight. Of course
all sorts of math can be done now to determine what happens during a
loop, high G's etc...
What is important is that the position of the header tank does not enter
into the equation until the main tank and fuel line leading to the
header tank is empty (or sucking a lot of air). When this happens the
reference point for calculating the positions (heights) changes. If the
fuel level in the header tank is below the bottom of the main tank the
engine will lean out, and if above it will tend to richen the mix when
transitioning from the main tank to the header.
Enough physics, I always use a header to trap the air bubbles that occur
when the main clunk meets air instead of fuel. By fixing the outlet of
the header tank in the dead centre of the tank (no clunk) it provides
the greatest protection from the air that eventually gets trapped in the
header (what ever orientation the heli is in). Keep the header inlet at
the top and very short to allow all the air to be purged during a fill.
I have no air in the tank at the start of a flight. As far as placement
goes, I try to keep the length of the plumbing to a minimum.
Do they really help keep a constant mix? Other than preventing the
leaning out due to bubbles I don't think so and the physics doesn't
support it either. Then again there are sooooo many other factors that
are hard to account for, that any change may help or hurt our setups.
Russ S.
Beavis
<willb...@aol.comxxx> writes
>Headers were also designed to eliminate any air bubbles and fuel foaming. It
>does this becuase the header tank is always full up and there is no room inside
>for it to foam and it will always trap the air bubbles preventing them from
>going into your engine. I have tried my heli's with an without them and
>personally I have seen no major improvements.
That's because your explanation is correct Will. The "header tank" is a
complete misnomer as it's only a fat piece of fuel tubing which works as
a bubble trap for any air that gets into the system. Trap the air, keep
the fuel going to the engine, engine keeps running. Get air in the fuel,
misture weakens, engine stops.
If no air gets into the line, the bubble trap hasn't got any bubbles to
trap so it's a waste of space. If it DOES trap bubbles, get rid of the
bubbles and you STILL don't need a "header tank".
Beav
--
E-mail me if you feel the desire at the usual place
Beavis at nachos dot demon dot co dot uk (No xxx's)
You can even visit my website at WWW.nachos.demon.co.uk
Intrepid
or even out needle settings. A header tank is nothing more than a big bubble
in the fuel line. It does help with air bubbles and it does add more things to
the system that can fail. Try this simple test. Mount a fuel tank a foot off
of the table, fill it with water and connect a header tank to it. Start a
siphon and while the main tank is draining raise and lower the header tank.
You will no change in fuel flow.
In article <36CCDC36...@usa.spamorama.net>, bmwebb
<bmw...@usa.spamorama.net> wrote:
>The biggest advantage I can figure is that it helps to maintain a
>constant fuel pressure (?) for the engine. As the fuel in the main tank
>gets lower with use, the fuel draw for the engine goes from a higher
>pressure (full tank) to a lower pressure (empty tasnk). The header tanks
>acts as a damper between the main tank and the carb, helping to maintain
>a more consistent fuel draw pressure to the carb. This evens out your
>mixture setting at the needle. Adds some needed flight time, too. I put
>one on mine, and it does work.
>
>Best I could do,
>Bradley
>
ser...@ibm.net
Elizebeth Burgess wrote in message <36CDCC52...@earthlink.net>...
heliko...@hotmail.com
gkg...@flash.net wrote:
> Some of us were discussing at the local hobby store what advantages a
> header tank provides on a heli and how it works. Many theories were
> presented but not many agreements. Any liquid dynamics experts out
> there?
>
source for your engine that will completely drain your main fuel tank.
kliff
helikopter13
Guillaume Hastoy
Gary Grant a écrit dans le message <36CC5B99...@flash.net>...
>Some of us were discussing at the local hobby store what advantages a
>header tank provides on a heli and how it works. Many theories were
>presented but not many agreements. Any liquid dynamics experts out
>there?
I'm answering this mail coz i'm experiencing bad fuel foaming problems right
now ( consecutive to tail rpm increase to 9200rpm )...
My experience with header tanks ? well...: here are 2 problems they didn't
solve AT ALL (for me) : 1) engine lean out throughout the flight 2) fuel
foaming .What were they good at ? : little to no air intake during
aerobatics at the end of a flight on low fuel , coz if you suck the fuel in
the middle of the header tank ( or even with a clunk, why not) , the air
inside the header tank ( yes THERE IS air in header tanks) won't go in the
fuel line or to the carburator ( you still have to land soon enough though
;-)
But i now prefer the felt-clunk solution (Robbe makes one) which takes 2
sec. to dry off when exposed to air , meanwhile the engine still sucks fuel
from the felt material. Then when the clunk meets fuel again , the air in
the felt leaves in the form of bubbles in the tank rather than in the fuel
line ( phew.... !! it could've been the opposite ;-) This way i only have
to fill up one tank instead of two :-)
Now for my emulsion problem , i heard that a few drops per gallon of this
stuff: ...............
<<ARMOR ALL® Leather Care Protectant preserves the supple feel and natural
luster of leather in one easy step. The rich, creamy lotion contains a
premium blend of ingredients to clean, protect, preserve and moisturize
leather surfaces from the car to the home, including clothing and
furniture>>
.............................will kiss my fuel foaming problems good-bye !!
serious !! I'm buying the stuff tomorrow !
Bye,
Guillaume
TRIP
There is a guy at my local club that swears by putting Armor All in his
fuel. He proved it to us by flying a flight in his plane with Armor All in
the fuel and a tank from a brand new gallon with out. Seeing is believing.
Trip
Guillaume Hastoy wrote in message <7al1mm$9a2$1...@bw107zhb.bluewin.ch>...
GoToHeli
Try putting some CHEER laundry detergent and an old sock in your tank
next time. You can fly as you clean!
Adding things to your fuel will certainly shorten the life of your
engine!
Boomstrike
>fuel. He proved it to us by flying a flight in his plane with Armor All in
>the fuel and a tank from a brand new gallon with out. Seeing is believing.
Rule number one:
Fix the cause, not the symptoms
boom
Beavis
<guil...@hastoy.com> writes
Hi G:
2 or 3 DROPS to a gallon will kill the foaming. Now you'll probably get
a lot of posts about how it'll affect your engine's running or lifespan,
or telling you to find the source of the vibes causing the foaming, but
after flying the older style Schluter heli's for years (well known for
foaming tanks no matter HOW well you balance everything) I never had a
problem with any engine of mine, and I've used Amorall for years.
The circular tanks made a good facsimile of a washing machine, but
Armorall kills it dead.
Guillaume Hastoy
Armorall with success . My engine quits almost on every backwards loop
where high Gs push the tank towards the chassis -->no more damping) only
at 1700 rpm and not at any other lower rpm --> it sure is fuel foaming .
I'll let you all know if Armorall solves the problem...
Thanks again,
Guillaume
>There is a guy at my local club that swears by putting Armor All in his
>fuel. He proved it to us by flying a flight in his plane with Armor All in
>the fuel and a tank from a brand new gallon with out. Seeing is believing.
>
>Trip
Beavis
<guil...@hastoy.com> writes
>Thanks a lot to Beav and Trip . It feels great to see that others have used
>Armorall with success . My engine quits almost on every backwards loop
> where high Gs push the tank towards the chassis -->no more damping) only
>at 1700 rpm and not at any other lower rpm --> it sure is fuel foaming .
>I'll let you all know if Armorall solves the problem...
G: Before you run your engine with this stuff try this. Get a new gallon
bottle and give it a good old shaking to make it foam and see how long
it takes for the foam to settle. Then ad a couple of drops and shake the
bottle again. NOW see how long it takes for the foam to disappear if it
appears at all.
If you do it one drop at a time, you'll use the minimum necessary and
have plenty over to polish the dash on your car, or the canopy of your
heli's :-)
Beavis
writes
>On Sat, 20 Feb 1999 02:26:15 GMT, "TRIP" <X...@xxx.XX> wrote:
>
>Try putting some CHEER laundry detergent and an old sock in your tank
>next time. You can fly as you clean!
>
>Adding things to your fuel will certainly shorten the life of your
>engine!
So which "things" will shorten it's life? Oil, methanol, nitro methane,
nitro propane, benzine, (all things found in fuels of different species
these days) what?
I told G: he'd get this type of response, but if you can tell me how 2
or 3 drops of Armorall will shorten the life of the engine, I'm willing
to listen.
Beavis
<booms...@aol.com> writes
>>There is a guy at my local club that swears by putting Armor All in his
>>fuel. He proved it to us by flying a flight in his plane with Armor All in
>>the fuel and a tank from a brand new gallon with out. Seeing is believing.
>
>
>Fix the cause, not the symptoms
Boom, if you have a solution to washing machine fuel tanks on some
heli's, I'll be the first to use it, but some heli's will foam for fun
and even dialling everything to less than 2 thou, and balancing
everything else to within 1/50th gram doesn't stop it.
The rear mounted tanks are the worst where the distance between the tank
and the engine is tiny and the tank is held rigidly and this problem has
been around since helicopters were introduced. When a heli foams and
you've done all there is to do an it STILL foams, the Armorall kills the
foam dead and the fuel in the tank doesn't have so much as a ripple in
it. This wouldn't happen if there was a serious mechanical reason for
the foaming. If the "problem" was anything to so with balance and
trueness of shafts (or whatever other mechanical thing could cause
foaming) then the Armorall wouldn't be a good idea, and in fact it
wouldn't work to well either.
If the foaming IS due to mechanical vibration, then YES you must find
the source and deal with it, but Guill: is no learner at this heli thing
and can probably outfly the vast majoritiy of guys on here and can
probably out-build 'em too, so he's already gone down the mechanical
route (I'd wager) and has reached the "Gnashing of teeth" and the
"Tearing of hair" stage, and if Armorall saves him from that, then I say
"Go for it"
Boomstrike
>Armorall with success . My engine quits almost on every backwards loop
> where high Gs push the tank towards the chassis -->no more damping) only
>at 1700 rpm and not at any other lower rpm --> it sure is fuel foaming .
>I'll let you all know if Armorall solves the problem...
>
>>fuel. He proved it to us by flying a flight in his plane with Armor All in
>>the fuel and a tank from a brand new gallon with out. Seeing is believing.
>>
>
>>Hi G:
>>
>>2 or 3 DROPS to a gallon will kill the foaming. Now you'll probably get
>>a lot of posts about how it'll affect your engine's running or lifespan,
>>or telling you to find the source of the vibes causing the foaming, but
>>after flying the older style Schluter heli's for years (well known for
>>foaming tanks no matter HOW well you balance everything) I never had a
>>problem with any engine of mine, and I've used Amorall for years.
>>
>>The circular tanks made a good facsimile of a washing machine, but
>>Armorall kills it dead.
>>
>>Beav
I will confess that my Schluter Campions and Scouts were the worst for this
problem. I finally put a rubber lord mount between where the tank bracket
attached to the rear of the mainframes and it dampened it out. Had to move the
bracket back a bit also if I remember correctly to make room for the damper.
I'm glad the Xcell stuff isn't so bad.
boom
Boomstrike
>the source and deal with it, but Guill: is no learner at this heli thing
>and can probably outfly the vast majoritiy of guys on here and can
>probably out-build 'em too, so he's already gone down the mechanical
>route (I'd wager) and has reached the "Gnashing of teeth" and the
>"Tearing of hair" stage, and if Armorall saves him from that, then I say
>"Go for it"
>
>
After thinking about it some more you have a few real good points (on your head
though!)<G>
Without knowing someone personally It's hard to know what their definition of
"balanced" is. Sounds like its not an issue here. On my other post on this
thread I mentioned how bad my Schluters had this problem and how i gave up on
balancing and mad a mounting mod to the machine.
Since it's near impossible to balance a single cylinder engine like we use(just
the engine,not the stuff attached to it) I suspect that the fundamental
frequency that the engine puts out foams the fuel. If the models design doesn't
dampen out that freq. range then it would definetly make sense to do something
else, short of redesign or major mods, to solve the problem. Armorall sounds
like the ticket1
boom
JIARSA
vibration which is present no matter how balanced your helicopter may be. The
header tank minimizes the possibilty of drawing in foam. The foam tend to lean
out your engine, and causes erratic engine operation. If you do 3D stuff, this
is added insurnce your helicopter will not go down due to fuel starvation.
Beavis
<booms...@aol.com> writes
This is what I've been trying to say Boom. The heli ITSELF doesn't
vibrate (so the Armorall isn't masking a real problem) but the tank
does. Damping out the tank from the frames helps with the foaming
problem but it's doing nothing OTHER than that. It's not addressing
anything other than the foaming tank, and with the "round-tank"
Schluters, that's what needs to be done if all the other stuff has been
checked (Usually)
Beavis
<booms...@aol.com> writes
>>If the foaming IS due to mechanical vibration, then YES you must find
>>the source and deal with it, but Guill: is no learner at this heli thing
>>and can probably outfly the vast majoritiy of guys on here and can
>>probably out-build 'em too, so he's already gone down the mechanical
>>route (I'd wager) and has reached the "Gnashing of teeth" and the
>>"Tearing of hair" stage, and if Armorall saves him from that, then I say
>>"Go for it"
>>
>>
>
>After thinking about it some more you have a few real good points (on your head
>though!)<G>
> Without knowing someone personally It's hard to know what their definition of
>"balanced" is. Sounds like its not an issue here. On my other post on this
>thread I mentioned how bad my Schluters had this problem and how i gave up on
>balancing and mad a mounting mod to the machine.
Yeah, it IS hard to REAllY establish what level of
building/flying/bullshitting some of us are at :-) I replied to your
other post too, so no point repeating it here.
>
>Since it's near impossible to balance a single cylinder engine like we use(just
>the engine,not the stuff attached to it) I suspect that the fundamental
>frequency that the engine puts out foams the fuel.
Absolutely my thoughts too, but there was a discussion in one of the
mags a while ago about just this subject. We had one guy NOT getting
foaming with high frequency vibes, and another NOT gettting them with
LOW freq vibes. One had the tank on an orbital sander (and so it went
on) but I think that the PROXIMITY of the tank to the engine plays a
part, but I'm certainly not going to "go to war" over that idea :-)
All I know is that those heli's with a round or perfectly upright
rectangular rear mounted tank (not angled like the X-cell Pro) have more
of a tendency towards washing machine emulutation than a front mounted
(or angled) style.
> If the models design doesn't
>dampen out that freq. range then it would definetly make sense to do something
>else, short of redesign or major mods, to solve the problem. Armorall sounds
>like the ticket1
It's that alright:-) (I doesn't polish the crap out of the engine like I
thought it would though:-)
Robert Mulligan
Beavis wrote in message <925C4JAb...@nachos.demon.co.uk>...
>>>>fuel. He proved it to us by flying a flight in his plane with Armor All
in
>>>>The circular tanks made a good facsimile of a washing machine, but
>>>>Armorall kills it dead.
Interesting... I am new to this, but I had thought that fuel tanks with
baffeling would stop this problem.... I spent 11 years on Submarines and 99%
of our tanks (Fuel and oil) had baffeling for this reason... afterall
driving a sub is a LOT like piloting a plane.
stev...@yahoo.com
wa...@ids.net (GoToHeli) wrote:
> On Sat, 20 Feb 1999 02:26:15 GMT, "TRIP" <X...@xxx.XX> wrote:
>
> Try putting some CHEER laundry detergent and an old sock in your tank
> next time. You can fly as you clean!
>
> Adding things to your fuel will certainly shorten the life of your
> engine!
>
> >
> >There is a guy at my local club that swears by putting Armor All in his
> >fuel. He proved it to us by flying a flight in his plane with Armor All in
> >
> >Trip
> >
> >>
> >>Guillaume
> >>
> >>http://www.hastoy.com
> >>
> >>A header tank does several things, but it DOESN'T do anything to maintain
the fuel pressure constant from beginning to end of the flight. It does act
as a bubble trap, which is good for 3D, and should help if you have a fuel
foaming problem in the main tank. It does help dampen any momentary
fluctuations in fuel pressure that can occur during maneuvers, which again
should help for 3D flight. It does add an easily seen extra reserve that
makes it less likely you'll accidentally run out of fuel - both because
you've got more to start with, and because it's easier to see when you're
getting low. Finally, it adds more complexity, and more parts to fail. This
last line is the clincher for me - I fly inverted, and do flips and hovering
rolls on my X-cells w/o a header tank, and w/o any motor problems. I
honestly think most helis don't need it, and you're just adding another
failure mode. Hope this helps. Steve.
Gary Grant
Thanks for the very informative answer on how header tanks work. Your
explanation opened some new thoughts and I wanted to run (type) them by
you, if you don't mind?
Carburetion works because of the difference in pressure (high seeks
low) that exists outside and inside the engine. This differential in
pressure occurrs at the greatest restriction which hopefully is located
at the metering jets (idle & main mixture screws) depending on the
throttle position.
So, isn't the tank or tanks just pressure with fuel being forced to, and
through the jets to the low pressure? By adding a header tank, it seems
that we then locate the pressure (thick tubing) closer (hopefully) to
the differential at the jet.
All this would then cause the differetial pressure to remain more
constant because the header tank stays full as long as the system is
plumbed right and the main tank stays full.
Some more of your thoughts on this matter would be greatly
appreciated.
Gary
Guillaume Hastoy
>I am new to this, but I had thought that fuel tanks with
>baffeling would stop this problem.... I spent 11 years on Submarines and
99%
>of our tanks (Fuel and oil) had baffeling for this reason... afterall
>driving a sub is a LOT like piloting a plane.
Interesting.. I know some r/c cars tanks have those baffles you're talking
about to reduce/eliminate fuel foaming . Do you think there's a way to
install baffles in a heli tank and still having the clunk beeing able to
move freely , as needed for aerobatics ? ( i'm *not* beeing ironical , i'm
really asking :-)
Bye,
Guillaume
http://www.hastoy.com - R/C helicopters
downloadable videos
MH-Design online shopping
XSNXS
The baffles used on liquids within submarines are in place to control rapid
mass movement or "weight shifting", so as to not dramatically effect the Center
of Gravity in varying angles of attack (both longitudinally or laterally). If
anything... baffles would contribute to greater aeration, or in this case...
foaming, if air is present in the system.
There are other means of effectively controlling induced air, such as fuel
bladders, however most model helicopters are using puffer (muffler) pressure to
help ensure a constant fuel flow.
There was a comment (I think be Beav) stating the X-Cell tank, which is mounted
at an angle... is less prone to fuel foaming. From a flow dynamics perspective,
this is an accurate statement. Waves (both sound and viscous) are "bounced" or
"reflected" when meeting an object. The composition of that object will also
have a dramatic effect on the intensity of same. The angle of the object,
relative to the wave will control or determine the dispersion rate, reflective
angle and intensity level of the wave.
In short, a wave rolling into a wall will be bounced back. A wave rolling on to
the beach will be absorbed. The X-Cell's fuel tank walls are at an angle
relative to the fuel's surface level, which results in less reverberation, thus
reduced fuel foaming.
Carl Camper
http://www.interlog.com/~jlogan/ultrac
John Bacon
fuel "Will NOT Foam!!" Come and watch mine, the fuel is almost still when in a stable hover....
(of course that is in the best one of my fleet) :-{)
Later,
JB
Beavis
<m...@here.net> writes
>
>Beavis wrote in message <925C4JAb...@nachos.demon.co.uk>...
>>In article <19990220125611...@ng11.aol.com>, Boomstrike
>><booms...@aol.com> writes
>>>>
>>>>>fuel. He proved it to us by flying a flight in his plane with Armor All
>in
>
>
>>>>>Armorall kills it dead.
>
>
>baffeling would stop this problem.... I spent 11 years on Submarines and 99%
>of our tanks (Fuel and oil) had baffeling for this reason... afterall
>driving a sub is a LOT like piloting a plane.
It's probably true to say that baffles in the tank WOULD help with
foaming, but it's a lot easier to chuck a couple of drops of Armorall in
the fuel bottle than it is to build and install said baffles.
Guillaume Hastoy
XSNXS a écrit dans le message <19990221102711...@ng-fq1.aol.com>...
RCKRZY1
In article <7aqd9q$n1k$2...@bw107zhb.bluewin.ch>, "Guillaume Hastoy"
<guil...@hastoy.com> writes:
>"Breaking" the =
>geomtry would probably help... I'll think about something ;-)
Ok how about bladder tanks ??
Food for thought
Adam Tucker
AMA 520901
Hurst Tx
ICQ#27191334
Remove "NOSPAM" to Reply by Email
Robert Mulligan
XSNXS wrote in message <19990221102711...@ng-fq1.aol.com>...
>Robert,
>
>The baffles used on liquids within submarines are in place to control rapid
>mass movement or "weight shifting", so as to not dramatically effect the
Center
>of Gravity in varying angles of attack (both longitudinally or laterally).
If
>anything... baffles would contribute to greater aeration, or in this
case...
>foaming, if air is present in the system.
>
>
mounted
>at an angle... is less prone to fuel foaming. From a flow dynamics
perspective,
>
>http://www.interlog.com/~jlogan/ultrac
True the main purpose of the baffles was to stop rapid weight movement but
they did have the added effect of minimizing aeration in the fuels and
oils... if the baffels were placed perpendicular to the bottom of the takn
I could see where this would not be a help, but placing them at a 15 or 20
degree angle would combine both the "wave" reduction effect you mentioned
and also stop weight movement so your 3D flying could be better controled.
Hmmm... Just a thought.
Robert Mulligan
rmul...@ix.netcom.com
Mike Phillips
Header tanks on my machines are an absolute must. At an engine speed of say 18k to
20k, if the fuel gets low in my main tank, the engine will lean some. Then it gets a
little hotter. During decents, it starts to over speed a bit. Sure, I could richen
the mitures a bit too, but that would reduce the power I'm trying to make. The
header tanks for me, keep the mixture far more consistant, than without them.
What is in Armor All? I know its alcohol based. What makes it reduce foaming? Since
I make my own fuel with only oil, Methanol and nitro, the additional foaming
reduction would be nice. I have no fuel foaming problems, but just to see the
difference in how the liquid behaves would be great.
Mike
Beavis
Phillips <mike_p...@XXXnon-hp-paloalto-om16.om.hp.com> writes
>Beavis,
>
>Header tanks on my machines are an absolute must. At an engine speed of say 18k
>to
>20k, if the fuel gets low in my main tank, the engine will lean some. Then it
>gets a
>little hotter. During decents, it starts to over speed a bit. Sure, I could
>richen
>the mitures a bit too, but that would reduce the power I'm trying to make. The
>header tanks for me, keep the mixture far more consistant, than without them.
Mike, I don't say that header tanks don't have some benefits in some
applications, just that for the majority of flying, they're not
necessary. If you're trying to extract evey ounce of power by running as
lean as poss, then ANYTHING that helps keep the fuel flowing to the carb
is a good idea, but most flyers are happy to accept slightly less than
max power and as a consequence, don't run into the lean run problems.
Still, having said all that, what we call "Header tanks" AREN'T really
header tanks at all. For them to be REAL header tanks, they'd need to
provide a constant "head" of pressure and as the pressure to the main
tank is controlled by exhaust tapping, (and so varies with throttle
position) then a constant pressure is never going to be.
>
>
>What is in Armor All?
It's a dash-board cleaner for cars.
>I know its alcohol based. What makes it reduce foaming?
I THINK it contains silicone which could be the operative chemical in
the foam-killing. Whatever it is, it really DOES work!
>Since
>I make my own fuel with only oil, Methanol and nitro, the additional foaming
>reduction would be nice. I have no fuel foaming problems, but just to see the
>difference in how the liquid behaves would be great.
Test some in an old fuel tank. Half fill it and shake it, and you'll
(obviousl) get the faom. Then drip a drop in the tank and shake it
again. It's almost a miracle :-)
>
>Mike
XSNXS
If you have a weak bladder, you'll have to stop too often. (couldn't resist)
Carl
Zbig
Put a tube in to about half the length of the bag so that you suck from the
middle.
These plasma bags are used a lot with gas turbines, where an air bubble will
definitely cause a flame out.
RCKRZY1 wrote in message <19990221225327...@ngol08.aol.com>...
>
>In article <7aqd9q$n1k$2...@bw107zhb.bluewin.ch>, "Guillaume Hastoy"
><guil...@hastoy.com> writes:
>
>>"Breaking" the =
>>geomtry would probably help... I'll think about something ;-)
>
>Ok how about bladder tanks ??
>
J W Schermerhorn
And- if you land too hard it will sound like a whoopy cushion. Then
you'll have to put a few drops of "Beano" in the fuel!
XSNXS wrote:
>
> >Ok how about bladder tanks ??
>
richard friedrich
> Still, having said all that, what we call "Header tanks" AREN'T really
> header tanks at all. For them to be REAL header tanks, they'd need to
> provide a constant "head" of pressure and as the pressure to the main
> tank is controlled by exhaust tapping, (and so varies with throttle
> position) then a constant pressure is never going to be.
>
Don't forget the gravitational field. There is also a component of total pressure
caused by the heigth of the fluid (potential energy) between the the pickup and the
surface of the fluid (fuel).
richard
Mike Phillips
Even when I was just a beginner, I could tell the difference with a header tank. So
do my fellow flyers.
This isn't another cultural thing is it?
Mike
Beavis
<dak...@ccwf.cc.utexas.edu> writes
And that's exactly where the "Header tank" falls at the first hurdle,
because it doesn't do anything to account for the height of the fuel.
(Commonly known as the fuel head). That's STILL totally dependant on
what's in the main tank, and as the level drops, so does the weight
pushing the fuel up the tubing to the carb THROUGH the "header" tank.
The "Bubble trap" description is right on the money, as that's exactly
what this type of tank installation provides. An escape route for any
air bubbles in the main tank, or fuel line UP TO the "header".
Beavis
Phillips <mike_p...@XXXnon-hp-paloalto-om16.om.hp.com> writes
>Beavis,
>
>Even when I was just a beginner, I could tell the difference with a header tank.
>So
>do my fellow flyers.
>
>This isn't another cultural thing is it?
What d'you mean ANOTHER cultural thing? Anyway it's a LOGICAL or PHYSICS
thing. If you can tell the difference then keep on using one, but I
can't be arsed because if there is a difference it's a tiny difference,
and has nothing to do with fuel head. Physics tell me that.
Nick Thompson
wrote:
I'm looking at a fitting header tank to my Concept, mainly so the fuel
level is more visable, but what is the 'correct plumbing' ?