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Fuel Flow Meter?


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Subject says it all, my newly acquired T300 has a simple clear plastic fuel level tube on the tank.  Not much good in flight to know how much fuel I have at anytime as I cannot see it from the cockpit.

Need ideas for fuel flow meter with a total amount consumed, reset meter on full tank and keep a track of fuel used etc.

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Just now, Marty_d said:

A mirror?  (Just trying to think laterally here!)  

 

Unfortunately, rear cockpit wall is blocking view, can’t stick head outside to look around…..might be OK IF I was a Giraffe 🙂

I will just suck it up and spend the bucks……IF it was a $300 rusty Corolla, would not care!

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With return lines to keep everything cool how is a normal F/F meter going to allow for the extra? A Flow measurement is a good thing but it must be reliable and pretty  accurate. Nev

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15 hours ago, jackc said:

Subject says it all, my newly acquired T300 has a simple clear plastic fuel level tube on the tank.  Not much good in flight to know how much fuel I have at anytime as I cannot see it from the cockpit.

Need ideas for fuel flow meter with a total amount consumed, reset meter on full tank and keep a track of fuel used etc.

Can you extend the top and bottom connection points forward and have sight tube on your side of the wall.

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The sight tube is very accurate for checking fuel level before takeoff especially if you calibrate it yourself. The fuel burn will always be fairly close to 17lph, most flights in a thruster are less than 1 hour, your back will give out before you empty a full tank in one go. Keep the simple plane simple. 

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2 hours ago, facthunter said:

With return lines to keep everything cool how is a normal F/F meter going to allow for the extra? A Flow measurement is a good thing but it must be reliable and pretty  accurate. Nev

Is this Q to me Nev??

 

If yes- I have found that by calibrating your fuel meter to total fuel consumed, you end up with a very very accurate  read out of fuel consumed/remaining. The fuel that returns to the tank has not been consumed so does not effect the total reading also the fuel return is only a small % of the total so any in flight inaccuracy is minimal (saves on investing dollars & complexity in a second sensor.)

 

Your actual fuel flow at any given time in the flight may be slightly out but for me what matters is not that you are doing 8L/hr loitering or 21L/hr in climb out but what is remaining in the tank.

 

The inflight read out will remain constant for any given power setting, and this gives a pretty good idea of power setting.

 

I have always kept a fuel log - so am able to verify the fuel flow meter setting/accuracy every time I fuel up.

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 A general comment skip but no problem I've had good F/F indicators and they indicate power too You certainly can't trust fuel gauges unless they are simple (sight gauge) or at The other end of the scale really complex and accurate. You are never allowed to go on the gauges alone.You have to substantiate it by another method as well.  For simple planes like a thruster if you know what fuel is on board convert it to a a time interval and allow 3/4 s of an hour or MORE for reserve .Note the time remaining and use a stop watch and when it's gone to where you calculated be near to landing on your destination aerodrome. Only a fuel leak or something weird  with the  engine will make the fuel disappear markedly faster than it does any other time.  Stop watches are good gear in many aspects of flying.    A good one will have elaps (total) time as well as the stop watch function .Nev

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One important thing is fuel flow, IF a blockage is occurring and flow drops and EGTs rise indicating a lean running condition then I need to make an immediate plan to land before the motor stops from seizure or no fuel. IF I get excess flow…….the. there is a leak, which in a Thruster is easily identified. Maybe as Facthunter said, a stop watch and even a dipstick for the tank.  would be OK.   I don’t want any sophisticated EIS system just a simple flow setup like the FC-10.

 

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Well - I was trained (GA) to fly on time based, on max possible fuel consumption. This was "wet hire" where most of the Cessna's I was flying did 32 L/hr.

Life was simpler, calculations were consistent. Fuel gauges was so erratic no one ever used them.

Now I own an aircraft, fitted with a magnificent Rotax 912ULS,  I can fly at different power settings for a cruise fuel flow 13-18L/hr. I only mention this because, now I am more likely to use the "econamy" option & I need to be more aware of duration ie it can only get worse /shorter.

This is particularly important when running into an unexpected/strong head wind.

Single pilot versus plus passenger/load, also has an impact (not previously highlighted in GA training, 32L/Hr covering almost every eventuality) in these small aircraft. As I generally fly alone,I flight plan on a fuel consumption that will accommodation a pax/load and this gives me a nice conservative planning figure (14L/h) for the occasional slightly higher cruise than normal or an unexpected head wind (to some degree).

I have been fortunate - my automotive style fuel gauge, has remained in calibration for many years and this combined with my fuel flow "computer" allows for very good real time fuel remaining indication.

In 11 years of flying behind my Rotax, I have only diverted once for additional fuel due to unexpected/forecast strong head winds - my fuel gauges/clock/ deteriorating ground speed, all gave me advanced warning, enabling me to plan a diversion, fuel up and continue to my destination without stress.

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You are required to plan on the POH figures or an established rate you can prove by records reliably PLUS whatever reserves is in vogue at the time  Could be something like 10% of flight fuel plus an hour at a specified real rate/ hour .If your G/S is out by more than 10% in these circumstances you won't make your destination without chewing into your fixed reserve.

My general approach is to never PLAN to arrive at the destination with Less than ONE hours fuel. I think this fits in with CASA's recent views about declaring a fuel situation..

 So at the planning stage you have decided for keeps what minimum fuel you need to have The only way you can make up fuel in flight is to achieve a better ground NM per Litre than you planned on. Ie make up time so you are then ahead of time arriving at EACH waypoint. Converting time to fuel is easy  18 litres/hr is  3 litres in 10 minutes. and at say 55 knots G/S 55/6 = 9 kms approx.gives you a distance relationship. to fuel and time. Check that out folks and let me know if you are happy. It's nice to double check your ability to make it so you don't make a BIG error of concept. You can be wrong to 3 or more decimal places or not add a "0" at the right time on the Prayer wheel. You can be "precisely" wrong by a long way. It's the big errors that will get you.  Nev

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27 minutes ago, Old Koreelah said:

A cheap kitchen timer stuck to panel has served me well.

Problemo - most kitchen timers seem to only run for 60 minutes - not great if you have a 6 hr duration (not that I fly for more than 2-3 hrs at a stretch)

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KISS. Know what you have before you start, know your fuel burn maximum, keep a check on time and land with at least 30 minutes fuel remaining. Worked for me for 40 years.

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23 minutes ago, kgwilson said:

KISS. Know what you have before you start, know your fuel burn maximum, keep a check on time and land with at least 30 minutes fuel remaining. Worked for me for 40 years.

Very good KG - just one, not so much, problem - I sort of touched on this in my previous post.

Now that I have the option to economise on fuel consumption and enjoy my time aloft, without watching the rental clock, I am more likely to have a lower than max cruise power fuel burn.

In effect this means that if you/I use max power fuel burn calculation, we are going to be landing with not just a bit more fuel (plus reserve) but a whole lot of fuel.

Not a problem you might say, better safe than empty/sorry.

However carrying more fuel than needed, this is extra weight, that  means extra energy to get up and stay up - higher fuel burn than the trip might have required.

I would advocate using a planed fuel burn that is representative of what you are actually intending to use.

This argument is moot, if you fly everywhere at max continuose power.

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Fair comment but I always reckon the only time you have too much fuel is when you are on fire. I rarely land with less than an hours fuel left and if I am going cross country I need much more than the trip plus reserve as I have to allow for alternates or return home if weather turns to custard. Doesn't normally happen due to good planning but can and has happened to me when I was 45 NM offshore and ran into unexpected and unforecasted weather.

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30 minutes ago, kgwilson said:

Fair comment but I always reckon the only time you have too much fuel is when you are on fire. I rarely land with less than an hours fuel left and if I am going cross country I need much more than the trip plus reserve as I have to allow for alternates or return home if weather turns to custard. Doesn't normally happen due to good planning but can and has happened to me when I was 45 NM offshore and ran into unexpected and unforecasted weather.

I am much the same however I have a main tank and a large auxiliary. This gives me plenty of scope to decide on carrying additional fuel or not. 

 

Like you, I try to plan well - not a chore for me as I enjoy the process. In fact it gives me the chance to "fly" the trip in my imagination, several times, befor the actual deed.

 

i have only turned back once - trip out to an airshow at Parkes. Unexpectedly strong (& increasing) head winds had me "hovering" over Bathurst. Ground speed "pedestrian". Got a phone call from Parks BIG DUST STORM coming in from the west. Turned around, 110 knot indicated with a ground speed of 160 kn, very fast return to base. Challenging landing in strong turbulence & remaining high fuel load.

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  • 3 weeks later...

Here's what mine has.

It is a clear tube inside another protective clear tube with marking labels on the post. Picture was taken before I got it flying.

It is joined to the original sight tube at the bottom, runs up this post and back along the top of the cockpit and tees back into the breather line. 

Very easy to see whilst flying.

I also have the GT-50 which is quite handy, it has a clock and stopwatch along with other features.

 

 IMG_6749.HEIC

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Off to another thought !

Scrap an old Drone to use that tiny camera, use phone to view ' camera image' .

Only need the mother-board, battery & camera.

spacesailor

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Hmmm

 

From the T300 I used to fly, the T500 I owned and the T600s in the UK I used to fly I am at a loss to understand the problem unless you cannot lift your arm and look back at the sight tube through the cutout in the centre of the cabin back.

 

In all of the Thruster two seaters I owned/flew there is a clear Perspex insert in the rear of the cabin through which I could see the sight tube that ran up the centre of the tank.  On mine I marked the ground attitude fuel on one side and inflight levels on the other ... and marked them Ground and Flight.

 

All I needed to do was lift my arm and look back under the armpit to see the fuel state.  Always ran a fuel log on the flight plans but used the sight tube to confirm/amend actual to plan as required.

Quite important in the T600's when you are flying around the UK and into/out of military airspace as you often got held or flown around the houses to get around them so fuel planning became more critical.

 

Here in OZ the majority of my Thruster flying was just local pootling around for an hour or so without any plans other than to go have some fun so I just ran from full tank and refilled to full after each flight.

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