skateosiris
Well-Known Member
Hi, just wondering if there is a way to mentally calculate fuel required for say a diversion, with out using the E6B computer?
Calculating Fuel consumption
- Thread starter skateosiris
- Start date
29.92inHg
Well-Known Member
mental math my friend.
using a 172 as an example with loose numbers (you will have yours from your flight plan)
If you know you are burning 10 gallons an hour, you establish your ground speed is 110 knots and the distance is say 15 miles
that is slighly less than 2 miles per minute at 15 miles is 8 minutes (est.) 8/60=4/30=2/15= about 1/7th of 10gal/hr about 1.2 gallons. ( i did this part as fast as I could type it I promise it was unedited)
If you check the actual math you get 8.1818 minutes (so the estimation was close) and you get 1.36 gallons (so again close)
Bottom line is do you have enough fuel. If the diversion ends up being larger than that (faster plane, longer distance, more fuel burn, etc...) you can work it out in a little more detail, however the E6B really isn't that hard to learn. Perhaps this will help.
using a 172 as an example with loose numbers (you will have yours from your flight plan)
If you know you are burning 10 gallons an hour, you establish your ground speed is 110 knots and the distance is say 15 miles
that is slighly less than 2 miles per minute at 15 miles is 8 minutes (est.) 8/60=4/30=2/15= about 1/7th of 10gal/hr about 1.2 gallons. ( i did this part as fast as I could type it I promise it was unedited)
If you check the actual math you get 8.1818 minutes (so the estimation was close) and you get 1.36 gallons (so again close)
Bottom line is do you have enough fuel. If the diversion ends up being larger than that (faster plane, longer distance, more fuel burn, etc...) you can work it out in a little more detail, however the E6B really isn't that hard to learn. Perhaps this will help.
I always did it via percent base. Meaning if it was say a 20 minute flight, thats 33 percent of my hourly fuel burn. Here is a little list:
You can interpolate for any other value to get a rough guestimate, then take that percentage of your gph for fuel burn.
- 15 min = 25%
- 20 min = 33%
- 30 min = 50%
- 40 min = 66%
- 45 min = 75%
You can interpolate for any other value to get a rough guestimate, then take that percentage of your gph for fuel burn.
jhugz
Well-Known Member
I will not let students use an E6B or plotter for the diversion on the X-Country:
I use what's called the rule of thumb method. Your finger is approx 5nm. Use that as a crude ruler to find your distance. A 172 cruises at about 100kt so you are moving about 1.5nm a minute. That will give you a ETE. Use a generic full burn (round up). Figure out your fuel burn using your ETE.
I use what's called the rule of thumb method. Your finger is approx 5nm. Use that as a crude ruler to find your distance. A 172 cruises at about 100kt so you are moving about 1.5nm a minute. That will give you a ETE. Use a generic full burn (round up). Figure out your fuel burn using your ETE.
I use mental pictures.
Say I'm doing 180 knots. That's 3 miles/minute. So at 50 miles, I'm going to get there in .... about 19 minutes. So let's say 20. I can mentally picture a clock and I know that 20 minutes is 1/3 of the way to an hour. If I'm burning 50gph, 1/3 of that is a 18-ish.
I know 15*3=45.
So if I add a few gallons (15+3=18) I'll be in the ballpark both on time and fuel.
-mini
Say I'm doing 180 knots. That's 3 miles/minute. So at 50 miles, I'm going to get there in .... about 19 minutes. So let's say 20. I can mentally picture a clock and I know that 20 minutes is 1/3 of the way to an hour. If I'm burning 50gph, 1/3 of that is a 18-ish.
I know 15*3=45.
So if I add a few gallons (15+3=18) I'll be in the ballpark both on time and fuel.
-mini
Crockrocket94
Well-Known Member
Direct to said airport on GPS(ETE), x Fuel Burn per HR= Amount Burned.
Sorry.
You can just use ROT, I mean, an example is the Cherokee 160 burns ~10gph, and if you know that it is about 100 miles to the destination, and you are traveling with a found ground speed of 100 knots, you know it will take one hour, then you know you need 10 gallons
Sorry.
You can just use ROT, I mean, an example is the Cherokee 160 burns ~10gph, and if you know that it is about 100 miles to the destination, and you are traveling with a found ground speed of 100 knots, you know it will take one hour, then you know you need 10 gallons
CoffeeIcePapers
Well-Hung Member
LOL.
ppragman
FLIPY FLAPS!
That's how I learned. That or a quick estimate. I also was taught to carry extra fuel, have a general idea of all of my probable alternates from before I takeoff, and use IFR fuel mins for most if not all flights.
When I flew in Kodiak, the rule was always carry enough fuel to fly all the way around the island. Doesn't matter how nice it is now, because that could change in thirty minutes. Down here in south east, I try to land with at least 45minutes of fuel at my alternate unless my load won't allow it.