Jim Meade Posted January 15, 2015 Report Share Posted January 15, 2015 Does anyone use Fltplan.com for flight planning? If so, how did you arrive at your fuel burn rates for the CTSW with 912ULS (or very similar) at various altitudes, etc.? I make some long trips but haven't thought to keep careful notes of my fuel burn at various density altitudes and throttle (rpm) settings. I need to start doing that in the future. If anyone has done so and is willing to share, I'd be grateful. Right now, I have some rather conservative numbers in my A/C specs list. What I'd like is to have the most exact numbers possible. Then I'd apply the conservative adjustment to the results, rather than build in a fudge factor that tends to get lost and can lead to inaccurate estimates. Anyway, this is a simple question - who of you use Fltplan.com for your CTSW (or equivalent) and where did you get your numbers? Thanks Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted January 15, 2015 Report Share Posted January 15, 2015 I have always used a simple 5gph @ 120kts TAS. I almost always fly WOT and cruise @ ~10,000' Link to comment Share on other sites More sharing options...
FlyingMonkey Posted January 15, 2015 Report Share Posted January 15, 2015 I usually plan for 5.5gph flying 5500-7500ft at 5200-5400rpm. That came out to within about 0.1-0.2gph when I flew 400nm to Florida last year. Link to comment Share on other sites More sharing options...
gbigs Posted January 15, 2015 Report Share Posted January 15, 2015 You can use one average number for altitudes below 12k feet DA. The bigger factor is gonna be your cross and headwinds anyway. The Dynon computes the fuel burn for the 912iS without sport upgrade around 4-5 gph @ 5300-5400rpm cruise. The average would be in the middle of that range at 4.5gph. Link to comment Share on other sites More sharing options...
Tom Baker Posted January 15, 2015 Report Share Posted January 15, 2015 You can use one average number for altitudes below 12k feet DA. The bigger factor is gonna be your cross and headwinds anyway. The Dynon computes the fuel burn for the 912iS without sport upgrade around 4-5 gph @ 5300-5400rpm cruise. The average would be in the middle of that range at 4.5gph. I know this will fall on deaf ears, but cross winds and head winds do not effect fuel burn per hour or true airspeed. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted January 15, 2015 Report Share Posted January 15, 2015 I know this will fall on deaf ears, but cross winds and head winds do not effect fuel burn per hour or true airspeed. At least they do effect flight planning. Link to comment Share on other sites More sharing options...
gbigs Posted January 15, 2015 Report Share Posted January 15, 2015 I know this will fall on deaf ears, but cross winds and head winds do not effect fuel burn per hour or true airspeed. Sure they do...if you have a 20kt headwind you will have a slower GROUND SPEED and therefore take LONGER to get there and therefore burn more fuel because you are in the air longer. Listening is not the issue, knowledge of fuel planning seems to be... Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted January 15, 2015 Report Share Posted January 15, 2015 Sure they do...if you have a 20kt headwind you will burn more fuel to get there. Maybe we should have a poll? Tom is correct 'cross winds and head winds do not effect fuel burn per hour or true airspeed.' 'Sure they do...if you have a 20kt headwind you will burn more fuel to get there.' [ however it will take more hours while your fuel burn per hour remains constant ] Link to comment Share on other sites More sharing options...
gbigs Posted January 15, 2015 Report Share Posted January 15, 2015 Maybe we should have a poll? Tom is correct 'cross winds and head winds do not effect fuel burn per hour or true airspeed.' 'Sure they do...if you have a 20kt headwind you will burn more fuel to get there.' [ however it will take more hours while your fuel burn per hour remains constant ] Tom is NOT correct. Because Tom misread my original response to Meade's question on flight planning for fuel (read the title of this thread). Once again the discussion is about 'gotcha' and not conveying real information. Fuel quantity and GPH and winds (ground speed) are used to fully calculate fuel requirements for a trip. Link to comment Share on other sites More sharing options...
WmInce Posted January 15, 2015 Report Share Posted January 15, 2015 Tom is NOT correct. Because Tom misread the point of my original post. Fuel burn per hour has no meaning in regard to flight planning for fuel. You need to also know how LONG you will be in the air to fully plan for fuel requirements. The original question was about flight planning and fuel planning. And that's why I said that headwind is more important in such planning. And I also gave the average fuel burn per hour based on engine RPM...which is also more accurate than saying WOT. So educate all of us about your fuel flight planning when you almost ran your brand new CT out of fuel. Link to comment Share on other sites More sharing options...
ctfarmer Posted January 15, 2015 Report Share Posted January 15, 2015 The fuel burn numbers needed by flight planning software to work out GS relate only to TAS. And another thing, the post asked about a SW with 912ULS so what point flapping your gums about another aircraft with an engine unrelated to the original request. What was asked for was accurate and relevant numbers. There is a very good performance supplement for the LS/912ULS fwiw. Link http://documents.flightdesignusa.com/AF04300006_00.pdf Link to comment Share on other sites More sharing options...
Rich Posted January 15, 2015 Report Share Posted January 15, 2015 Jim, I use Flightplan and sometimes AOPA flight planner set for 5.5 GPH at 75% power (5200RPM). My 796 is set the same way. It has come very close to actual fuel burn. This past Saturday my trip down to NC from PA in a Sting S4: 485NM 4:10 TT 27 gal. avfuel/mogas mix 4500 MSL 5400/5420 RPM Approx. 85% power setting 6.5 GPH 115.5 average KTS Ground speed (112 KIAS) Winds: West @ 9K with an occasional 3KTS from the NW OAT ranged from 0*F to 25*F. DA was not an issue. Probably lower than 4500 with those temps. I burned and extra 1 GPH with the higher power setting to beet the sunset and approaching wx. The time beat my other trips to NC by 30 minutes. with an additional 4 gallons used with winds approx. the same I hope that helps somewhat. On another note, I never made it to Sebring due to the wx closing in from the NC/SC border south to FL. I've been waiting for some ceiling and visibility for the past five days Will try to make Tampa Saturday to meet with family. Link to comment Share on other sites More sharing options...
Top Cat Posted January 15, 2015 Report Share Posted January 15, 2015 Tom is NOT correct. Because Tom misread my original response to Meade's question on flight planning for fuel (read the title of this thread). Once again the discussion is about 'gotcha' and not conveying real information. Fuel quantity and GPH and winds (ground speed) are used to fully calculate fuel requirements for a trip. If the RATE of burn is 5 gph then the amount of fuel you need for the flight is the RATE per hour x the length of the flight, plus reserve. On a day with a headwind then the length of the flight will be longer and the amount of reserve fuel may need to be increased/decreased. On a day with a tailwind then the opposite can be used. Crosswinds can be used to compute whether they affect the groundspeed with a headwind component, or a tailwind, or don't affect groundspeed. Either way, the RATE of fuel burn per hour is needed which is what the thread poster was asking. The TIME at the RATE is part of how you determine your fuel requirement. There is no 'gotcha' unless you are making careless presumptions in your own flight planning, which it appears you are. For PLANNING you use a RATE per hour to calculate the fuel load prior to departure. Once airborne you can recalculate ground speeds and adjust your power setting to reduce the RATE of fuel burn. Your Dynon may indicate that your actual burn is better than the one you used for PLANNING. However, being conservative with your planning is a good thing. You would need to understand the concept of how fuel burn RATE times length of flight plus legal reserve determines the fuel requirements for a flight. Relying on a Dynon to do it alone for you is likely dangerous and folly. Link to comment Share on other sites More sharing options...
Doug G. Posted January 15, 2015 Report Share Posted January 15, 2015 I calculate on 5 gph and use 110kts with a one hour reserve. These are conservative as my normal burn is 4.5 and I usually cruise at 5000rpm which gives me gives me a bit more than 110kts ground speed on average. The reality is that I have at least 4-5 hours for fuel and plan stops at 2 or 3 hours for longer trips. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted January 15, 2015 Report Share Posted January 15, 2015 Tom is NOT correct. Because Tom misread my original response to Meade's question on flight planning for fuel (read the title of this thread). Once again the discussion is about 'gotcha' and not conveying real information. Fuel quantity and GPH and winds (ground speed) are used to fully calculate fuel requirements for a trip. Tom is correct and he used precise language to keep his meaning crystal clear. Your first statement 'You can use one average number for altitudes below 12k feet DA.' has no value, it is hard to see your intended meaning. Your next statement 'The bigger factor is gonna be your cross and headwinds anyway.' shows that you are thinking about fuel required and not the fundamentals of flight planning that include TAS, head/tail wind component, ...etc. IOW we plan flights based on distance and performance and then adjust for winds. Knowing that TAS isn't effected by winds is fundamental. Link to comment Share on other sites More sharing options...
WmInce Posted January 15, 2015 Report Share Posted January 15, 2015 . . . Your next statement [100Hamburger] 'The bigger factor is gonna be your cross and headwinds anyway.' shows that you are thinking about fuel required and not the fundamentals of flight planning that include TAS, head/tail wind component, ...etc. IOW we plan flights based on distance and performance and then adjust for winds. Knowing that TAS isn't effected by winds is fundamental. That seems to be a major problem . . . lack of fundamentals. How can someone be signed off without being well grounded in the fundamentals? . . . :huh: Link to comment Share on other sites More sharing options...
coppercity Posted January 16, 2015 Report Share Posted January 16, 2015 I use 117kts TAS and 5.5gph for most of my planning apps. Many don't account for climb and descent TAS or fuel burns so keep in mind on those long climbs you may burn 7gph for awhile. Link to comment Share on other sites More sharing options...
Jim Meade Posted January 16, 2015 Author Report Share Posted January 16, 2015 The fuel burn numbers needed by flight planning software to work out GS relate only to TAS. And another thing, the post asked about a SW with 912ULS so what point flapping your gums about another aircraft with an engine unrelated to the original request. What was asked for was accurate and relevant numbers. There is a very good performance supplement for the LS/912ULS fwiw. Link http://documents.flightdesignusa.com/AF04300006_00.pdf Thanks very much. I'm ashamed to say I'd forgotten about this document. I am sure I can work with it as a good baseline and then modify the numbers based on recorded flghts. Thanks again. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted January 16, 2015 Report Share Posted January 16, 2015 I use 117kts TAS and 5.5gph for most of my planning apps. Many don't account for climb and descent TAS or fuel burns so keep in mind on those long climbs you may burn 7gph for awhile. In my experience that is a pretty accurate estimate. 115kt is about what I would see at about 5200rpm, which is around 5 to 5.2gph. Include climb times to 5500-7500ft from 1000ft MSL and you are dead on. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted January 16, 2015 Report Share Posted January 16, 2015 In my experience that is a pretty accurate estimate. 115kt is about what I would see at about 5200rpm, which is around 5 to 5.2gph. Include climb times to 5500-7500ft from 1000ft MSL and you are dead on. Dead on for sea level guys who fly in dense air. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted January 16, 2015 Report Share Posted January 16, 2015 Dead on for sea level guys who fly in dense air. Yeah, you highlanders have a different set of burns for sure. IIRC you are WOT at cruise burning ~4.5gph, is that right? What RPM does that get you? Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted January 16, 2015 Report Share Posted January 16, 2015 Yeah, you highlanders have a different set of burns for sure. IIRC you are WOT at cruise burning ~4.5gph, is that right? What RPM does that get you? It gets you any RPM you want all you have to do is adjust the prop. Peak performance is at 7,500' DA so most of you are too low and I"m mostly too high. WOT @ 10,000' @ 5,500 RPM is probably 5gph. Link to comment Share on other sites More sharing options...
Doug G. Posted January 17, 2015 Report Share Posted January 17, 2015 I get about 4.5 gph @ 5,000 rpm, both on Dynon and on the tank stick. Most of my flights are 3,500 - 4,500ft. Link to comment Share on other sites More sharing options...
WmInce Posted January 17, 2015 Report Share Posted January 17, 2015 I get about 4.5 gph @ 5,000 rpm, both on Dynon and on the tank stick. Most of my flights are 3,500 - 4,500ft.Doug,Using those numbers, what airspeed are you developing? Do you have the tundra wheels and fairings? Link to comment Share on other sites More sharing options...
Doug G. Posted January 17, 2015 Report Share Posted January 17, 2015 Between 105 & 110kts. standard wheels and fairings. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.