View Full Version : fuel consumption rate for C152
27th Nov 2004, 20:48
I have a question about fuel consumption per hour for the Cessna 152.
Quite suprisingly, I find that everybody has different figures to tell.
Accordigng to my flying instructor it was 24 litres of fuel per hour at cruise power setting (full mixture I presume since it was always left at full mixture setting).
I asked another PPL holder who flies the 152 he says he uses 16 litres an hour! Thats a huge 8 litres of difference compared to the figure I use in fuel planning. I have heard other variety of figures too.
I thought it might be interesting to find what kind of figures people here use??
Gertrude the Wombat
27th Nov 2004, 21:37
I was told to use 7 USG/H (26.5l) for the ones I used to fly. The book figure was nearer 5.5 (21) for average conditions but they were not new aircraft and could not be expected to perform to the book.
If your instructor said 24 litres, and it was the same type of aircraft with the same book figures, then he was being a little less cautions than my instructor; there's no reason to suppose that he wasn't correct for your particular aircraft.
Anyone calculating on 16 litres must have been flying a completely different variety of 152.
Which is not to say he was wrong. You start by looking in the POH for your individual aircraft and use a higher figure if so advised or if that's what you find it burns. There are probably other reasons for adding fudge factors but I don't know what allowances to calculate as I've always been told the fudge factors by instructors. If you friend has done this, starting with his book for his individual aircraft, and come up with 16 then he's probably right, but in my very limited experience I've never seen a 152 POH that suggests it burns that little.
Others will no doubt be along in a moment with better information.
One thing that's for sure is that it won't burn less than it says in the book.
28th Nov 2004, 01:01
My aerobat as follows:
If mixture left fully rich 32 litres per hour.
If leaned in the cruise 27 litres per hour.
Both very consistent figures, usually at MAUW (not sure if that makes a huge difference!)
Edited to add: at 2400 and 105 knots IAS
28th Nov 2004, 12:01
My 152's burn 23lph at 2300rpm which gives 98kts indicated airspeed. Leaned out which we do above 2500ft they burn 19lph.
We have a fuel scan 450 fuel computer installed in both planes correctly calibrated. The data is bang on and is born out by the fuel used which we record when we refill.
It is possible to get 16lph at altitude corrctly leaned but you are only flying at about 78kts. The maximum they burn is 33lph which is full chat in the climb.
If I fly ours at 105kts the fuel burn is 26lph.
I have put more than 700hrs on my particular aircraft since I had the fuelscan fittted and have never seen these figures vary.
It is worth noting that the condition of the engine and the prop will will vary this figures of you are flying constant airpspeed but if flying constant RPM then they change very little.
28th Nov 2004, 13:16
6 usg /hr is a good ball park to use for these 100/112 engines, which also makes fuel planning a breeze, there is a small safety factor built in, plus when you add the normal diversion fuel plus 45 minutes plus 10% reserves you are well covered... keep it simple TR
28th Nov 2004, 20:14
In my opinion, too few pilots know what their exact fuel-burn is. There really is no point anybody saying "a 152 burns xx litres per hour", because it depends on how you fly it.
What power setting do you use?
Do you lean the engine?
If so, how do you lean it?
Every time you fly, you should measure (using a dipstick) how much fuel is in the tanks before your flight, and how much remains afterwards. This is the only way of knowing what fuel burn you get.
Once you've done this for a little while, then you can start having real confidence in your fuel calculations. Too many pilots just fill to the brim every time, thinking that this gives them maximum safety. It doesn't if they're operating off a shorter runway on a hot day - it actually diminishes their safety margins. And sooner or later you'll find yourself needing to depart an airfield that has no fuel. If you've never put your fuel calculations to the test then how can you know whether your departure is going to be safe? To take only enough fuel for your journey plus sensible diversion requires that you know for certain what your own fuel-burn is.
If you measure your own personal fuel-burn then you'll find it's incredibly consistent (assuming you always use the same power setting and leaning technique). You should be able to predict to the nearest gallon how much fuel is on board at the end of every flight.
The POH figures are the best starting point (even my 1959 172 burns fairly close to book figures if you fly using book technique), but ultimately you must ignore everyone else's figures and use your own.
Of course, all of this is made much easier if you always fly the same aircraft. But if you rent, it's going to be a little harder - but still not impossible.
28th Nov 2004, 20:18
Isn't that what I said?:O
28th Nov 2004, 20:35
Isn't that what I said?
If you did, then you concealed it well! :p
You gave lots of figures that may be relevant to the 152's that you have flown, but without saying exactly what your leaning technique is. So all your figures are irrelevant to anyone else.
The only relevant figures are the ones that you measure, flying your aircraft (or the one that you rent), using your engine management technique.
That's the point I was making (although I wasn't aiming it at you in particular).
28th Nov 2004, 20:52
We were agreeing largly..... :)
I have a lot of time in 152's and have found them v ery consistant not just on the personal leaning technique you mention but accross the board. My friends who fly my aircraft occassionally manage the same fuel flow figures as me I think the leaning range and operating range generally on a 152 is pretty narrow so it is easy to get consistant results.
The problem with actually measuring the fuel us on a 152 is that unless you have something like a fuel computer or diligantly measure the fuel used on every flight by checking at the pumps is accuracy in dipping the tanks. 2 people can dip the tanks using the same stick and get different readings due to very minor differences in the position of the stick and the angle they put it into the tank.
I think this is where the majority of the myths come from about fuel consumption!
I reqularily fly to 3.5hrs on single flights, a thing that brings most people out in a cold sweat!
I could not agree more about the people who just fill it up and hoipe for the best. Some of the places mine has been in would not be possible at full fuel!
30th Nov 2004, 09:47
In theory it’s 6USG/hr giving you 4 hours endurance with 24USG tanks. I prefer to use 7USG/hr, giving me 2.5 hrs + reserve. (If anyone can stand more than 2.5hrs in a 152, they’re a better man than me). :)
The ones I fly tend to use around 6.5USG/hr (local trips <3,500’, 90KIAS, fully rich) so 7 is a nice round number to use for planning, and gives you a decent margin for error.
30th Nov 2004, 15:47
I have a lot of time in 152's Please accept my condolences. :p