Webb

Webb

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When going cross country, what speed (TAS) and fuel burn do you plan?

I'll start it out.

RV7A - 160 knots @ 10 gals/hr
 
RV-6A, 180 HP FP prop, one Lightspeed/one mag

150 knots groundspeed (usually 155 but 150 is easier) and 7 GPH.

Cruise altitude typically above 12,500'
 
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154kts...9gph..(usually ends up little over 8).. the 154 seems to work our pretty close for my 6A..0-360 FP sen...
 
I plan Conservatively

TAS is not very meaningful when you are calculating a flight plan. If you do not maintain the flight plan ground speed that is when you are in danger of not reaching your destination. I flight plan using a ground speed of 150 kts and 10 gph burn rate with WOT and 2450 rpm for normal travel and I plan to have 1 hour of fuel in the tank at the destination. For racing I use 170 kts, 14.1 gph, WOT, 2720 rpm and VFR minimum 0.5 hr in the tank at the destination. In a race such as the AirVenture Cup where the course is long I calculate the minimum groundspeed needed for 0.5 fuel remaining at the end and I really watch the ground speed closely. If I can't maintain some margin over the calculated minimum safe VFR completion ground speed I have to find a better altitude or change settings to conserve fuel. True airspeed is meaningless in this context except for pride. Oh yes, don't forget to really fill your tanks.

Bob Axsom
 
TAS

I am with Bob on this one, TAS doesn't mean much.
I plan 150k and 10gph, with at least 8 gal reserve.
I plan 3 hour legs.
I look on airnav to find the cheep gas, if it is short of 3 hours I am ready to get out any way. 3 hours x 10 = 30 so I have more resreve than I need most of the time.
 
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Bob, I'll politely disagree... TAS is *very* meaningful when flight planning. Of course, you then have to apply the winds aloft (at least what's predicted) to it to figure out your ground speed (to calculate time enroute)... I'm not sold on using a "random" ground speed that you may not even be able to achieve (in winter time, for example)... :)
 
Jaypratt said:
I am with Bob on this one, TAS doesn't mean much.
I plan 150k and 10gph, with at least 8 gal reserve.
I plan 3 hour legs.
I look on airnav to find the cheep gas, if it is short of 3 hours I am ready to get out any way. 3 hours x 10 = 30 so I have more resreve than I need most of the time.
Click to expand...

Same as Bob and Jay. Can easily do on less than 10gph if I slow down, but I don't plan to always fly slow... :D

L.Adamson --- RV6A
 
For flight planning I use 165 kts and 9 gal/hr. These are conservative on both
counts. Dan C has a great weather site that allows you to create profiles.
Using his route page and selecting the profile you think you might use will
give honest numbers (if yours are) at various altitudes if the winds aloft
forecasts are accurate. Works for me.

http://www.weathermeister.com
 
GPS tells me how long until I reach a certain point.

RMI fuel totalizer function tells me how much endurance I have at the current power setting. Almost always the fuel endurance is higher than time enroute...usually being closest during climbout.

But upon reaching cruise altitude where speed picks up the fuel reserves increase. Fuel management is easy even for me.

On my return from LA, I wanted minimal fuel onboard after getting home so I could lube the fuel selector. I think I still have 12 gallons which is more than I wanted and far more than VFR minimum.

I still use 150 knots groundspeed for planning and adjust for headwinds/tailwinds. I always know in flight how much reserve I have so can make an additional fuel stop if needed. I think I have made an extra fuel stop once. My bad in not filling both tanks prior to departure. Yes, I made a mistake.
 
Somewhat subsonic

jferraro16 said:
LOL

I was a T-41 IP at the Air Force Academy. We had a "Friday Patch" for our flight suits with ".14 Mach" or something on it...thought we were hilarious.

Joe
Click to expand...

Well clear of the "coffin corner" you say? ;)

John Clark
RV8 N18U "Sunshine"
KSBA
 
Super Six numbers

With the gas guzzler up front, I've been using 200 KTAS and 12 GPH as a SWAG planning rule of thumb. (50%ish more fuel flow for 25%ish more smash...ah the price of speed ;)). That's of course no-wind, as Bob and others pointed out.

200 also makes it easy to use the old government issue "200 mile pen" on the chart for rough guestimates in initial planning! I normally plan for 400NMish (two pen-lengths) legs, and use that in Airnav to find cheapo fuel stops too.

In Weathermeister, I stayed a little conservative, and set up the profile as:
Climb - 130 KTS/18 GPH (1500 FPM Climb)
Cruise - 195 KTS/12 GPH (WOT/2300 RPM @ 10.5K for a baseline)
Descent - 205 KTS/12 GPH (500 FPM Descent)

It'll do a little better in most cases, but the WM altitude optimizer with winds considered really seems to nail it pretty close with those numbers, and on the few X-Cs I've done since using the site, it's been very consistent. Did a 430 NM Reno to San Diego trip and landed within a gallon or less of what WM forecast (2.1 hrs with a little tailwind and 11.9 GPH avg burn)...pretty cool program!! (And thanks to VAF bubbas for the lead to it!)

For Joe and John, I'm a 100 #/min guy at work too, and remember seeing an SR-71 pilot with a very cool patch that had nothing but his airplane planform with a big red "3+" in the middle. Hmmmm, wonder if I can make one with a .3+... :)

Would be interesting to hear what other Super 6/8 guys and Rocket guys are using as well.

Cheers,
Bob
 
OK Guys

Hey - I want to get a realistic ideal of how we stack up against what the Mothership has on the performance page. Yes I can go faster or slower, yes I can burn more or less.....but as each of you know, each plane has it's own personality and most of us find out where the sweet spot we like to cruise and go someplace is.

Those of us that travel have a pretty good ideal of what realistic numbers are. I'm trying to wade through all the bovine scotogy out there.

So far, this is what I've seen in the earlier part of this post:

In knots and gal/hr

RV6 - 167/8.7
RV6A - 150/7 154/9 150/10
Super 6 - 195/12
RV7A - 160/10
RV8 - 170/8.2 150/10
RV8A - 165/9
 
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Darylat8750ft said:
Woverine Hunter,
Always liked the DC9. At 100lbs a min. even I could keep track counting on my fingers and toes. :D
Daryl
Click to expand...

A good clock was helpful in the F-86L.

Flights were seldom longer than 50 minutes - the thing carried 5525 pounds of fuel and was no slouch burning it. And if you were a dumb student on a first mission and forgot to unplug the burner after take off, it could be as short as 7 minutes - the burner really gulped fuel. I can still hear the IP in a chase plane screaming UNPLUG THE BURNER as he fell farther and farther behind. That first flight was a real kick in the butt, burner and all, as there were no 2 seat 86's in those days.

That's what we need in these RV's to get out of short strips - a burner of some sort to kick up the HP 100% or so for a short time. :)

I haven't had a chance to do a cruise burn check with this airplane and the 0360 but used to get 160 KTAS at 8 gph in the Cozy. If this thing does as well, I will be pleased. The best I could get out of the Subby was 143 KTAS at 8 gph.
 
The Motherships numbers are very representitive of the performance with
the prop and engine combos they indicate. Speed vrs fuel is a function
of how far forward the black, blue and red knobs are. My numbers for
my -8A are predicated on 60 -65% power 500 feet either side of 10K feet.
My 165/9 is for flight planning. I go faster and use less fuel than that, but I go slower and use more in climb so this number seems to work out. Folks should have posted more detail (like the Super 6).
Those with electronic ignition, should burn less fuel. I have mags.
 
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Numbers

RV7 IO360 ECI, WW200RV prop.

I use 165kts and 8.5 gph. Works great for planning. Day of flight, I apply real numbers from Weathermeister or EAA flight planner. Usually pretty close.
 
Speed costs money...

195KTAS/11.2GPH (approx 22 squared) in the 550 Evo @ 7500MSL -- still in the test period, and I have not tried higher, or other power settings, yet.

Haven't tried flying x-cy with the Falcons either, but Ole 84 would show about 145KIAS @ 7.2GPH. This was at 19"/1800 to stay with the group; 7+ hrs endurance!:eek:

84 would do 200KTAS @15.5 on 9.2GPH...the 550 should do a bit better.

Carry on!
Mark
 
RV-8 170kts and 8.5
Sometimes I do better:)
my.php
 
RV6A performance

It seems the Mothership specs out prop and engine combos for every model except the 6 series on their performance page. I am assuming they are using a c/s prop based on the climb numbers.

Does anyone know?
 
You have to be careful in the compare

Flight planning numbers (generally conservative) and performance numbers (generally on the edge of extreme reach) can vary greatly.

Bob Axsom
 
OT

sonny junell said:
Can I see some RV-10 numbers?
Click to expand...
OK, this has nothing to do with the subject but I am so creeped out by Sonny's avatar that I don't want to go near the computer.

Please, something else!!! I would be willing to head up the fund drive for the graphics work. I'm thinking maybe a nice bunny rabbit or something.
 
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n5lp said:
OK, this has nothing to do with the subject but I am so creeped out by Sonny's avatar that I don't want to go near the computer.

Please, something else!!! I would be willing to head up the fund drive for the graphics work. I'm thinking maybe a nice bunny rabbit or something.
Click to expand...

Larry, now how are are you going to feel if that is his real picture and what you are seeing is his actual "RV Grin?" :eek:

Oh, and to remain on topic I plan for 155 knots at 8 gph but see closer to 162 knots at 7 gph in my 9A.
 
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Not an RV, but 165 KTAS/14GPH in the V35 Bonanza. Sure shows how efficient the RVs really are though.
 
Bryan Wood said:
That's nice. Those of us flying trainers like to be included too. ;)
Click to expand...

That's okay, as the local Rockets/ F1's make me look like a turtle. It's all relative... :D We all space ourselves for the 150 mile brunch on Sundays. The Piper Cub's takeoff a half hour early, and land 15 minutes late :)

L.Adamson
 
Added More

In knots and gal/hr, and the Van's number listed is an average (see note below)

RV3 - (Vans 157/7.5)
RV4 - (Vans 161/8)
RV6 - (Vans 159/9.5) 167/8.7
RV6A - (Vans 157/9.5) 150/7 154/9 150/10 AVG-151/8.7
RV7 - (Vans 165/10.5)
RV7A - (Vans 163/10.5) 160/10 165/8.5 AVG-163/9.3
RV8 - (Vans 168/10.5) 170/8.2 150/10 170/8.5 AVG-163/8.9
RV8A - (vans 166/10.5) 165/9 165/9 AVG-165/9
RV9A - (Vans 148/9) 155/8
RV10 - (Vans 161/15)
F1 - 195/11.2
Super 6 - 195/12

And of course, Sonny get's no respect asking for 10 numbers.

Keep em' coming folks. I would love to see at least 10 entries for each type of plane to get a respectable average. I'll throw the highest and lowest speed out for the average later.

For kicks and giggles, I went to the Mothership and did some averages. I used all speeds posted (75% and 55%) for all the different HP engines to get a middle average speed and called the gas tank a 4 hour tank and divided the # gallons by 4 for estimated fuel burn.
 
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Aaaaah, yes.......

KISS....3 miles per minute and 9GPH....this way my buddy with his '03 Cirrus can keep up:D

cya,
 
I forgot to add what I use today (with FP.. we'll see what C/S does next month)... RV-7A 155tas @ 7.3 gph at "normal" altitudes (and 6gph or less at O2 alts for same speed)...

Signed,
"Just say no to 10gph :) "
 
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o-360, fp sensi, slick mags, tas 150 kts, 8gph, tas 165kts 9.5 gph leaned to rough then 1 1/2 turns in. lots of car gas mixed with 1ooll. a little marvel for good luck. keep on flying. just turned over 3,500 hobbs time. ;)
img2268.jpg
 
A few more

Here are a few more:

In knots and gal/hr, and the Van's number listed is an average from their website

RV3 - (Vans 157/7.5)
RV4 - (Vans 161/8)
RV6 - (Vans 159/9.5) 167/8.7
RV6A - (Vans 157/9.5) 150/7 154/9 150/10 157/9 150/8 165/9.5 AVG-154/8.8
RV7 - (Vans 165/10.5)
RV7A - (Vans 163/10.5) 160/10 165/8.5 155/7.3 AVG-160/8.6
RV8 - (Vans 168/10.5) 170/8.2 150/10 170/8.5 AVG-163/8.9
RV8A - (vans 166/10.5) 165/9 165/9 AVG-165/9
RV9A - (Vans 148/9) 155/8
RV10 - (Vans 161/15)
F1 - 195/11.2
Super 6 - 195/12

Sometimes when I read the fuel burn, I feel like I've got a pig under the cowl. I just flew back from Mobile. Including taxi, climb of 6,500 feet from sea level, cruise, and landing, I used 10.3 gallons for 1 hour and 1 minute of flight time. I ran 23.5/2,250 (IO360/CS) at 85F ROP. My TAS was 161knots. I can get more out of the engine but fuel flow goes up rather rapidly.

If I tried to run fuel flow at some of the above flow rates, my EGT's would be screaming. After my leaning, the cylinder head temp spread is 4 degrees total spread so I know the engine is balanced out. The EGT ROP #'s are also a total spread of 10 degrees of each other.

Am I missing something here or are your guys cooking your valves?
 
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Not 150k and 10gal

150k,,, I get faster and 10 gal per I get better,,,or less.. Its more like 160k and 8.7 gal per hour,,, but planing...
What I plan is not what I get. Fuel burn more or less,,,but time is another thing.

I plan 3 hour legs + -. I start with 42 gallons, RV8, I do not want to plan a trip that has no more risk than necessary, IE planing to the nth gal per minute.
The 8/7 will go 5 hours easy, but not with me on board. 3 hours is a good leg.... I like low and slow,, and fast, regardless, I know that I will not run low on gas and have a good reserve.
I have landed and found that there is no gas and had to go elsewhere. Last year in the Bahamas we landed and had to do to another Island, glad I wasn't cutting it close that day.
Carrying around 10 to 12 gallons you are not going to use can be a good thing.
 
Mine is a -7A, O-360, fixed pitch Sensenich, left mag, right Lightspeed. Here's my DUATS profile:

Climb: TAS 130 kts. @ 800 fpm (usually indicate 120 kts.)
Cruise: TAS 155 kts. (2550 to 2650 rpm @ 8500 to 9500)
Descent: TAS 160 kts. @ 300 fpm
Fuel consumption: 1st hr. is 8.5 gph, 2nd hr. and beyond 7.7 gph.

I consistently am within 5 minutes of flight planned ETE, using slightly less than planned fuel.

At cruise, I run LOP 10 to 20 degrees. I find cracking the carb heat an 1/8" to 1/4" brings EGTs within 30 degrees of each other. At cruise, I know things are going my way when I see a ground speed (in knots) at least 20 times my fuel burn.

Here's a statistic I calculate just for grins, MPG(statute miles per gallon). 90% of the time on a 2 - 3 hr. trip, it's between 20 and 25 mpg using airport point to point distances unless I get a huge detour or holding. My average over the last 3 years and 300 hours is about 22 mpg, all on 100LL.

Another tidbit: I consistently burn 2 gallons from engine start up at 1000 MSL up through 8000 MSL, averaging 12 gph over 10 minutes.

TAS is used on flight plans. I use 155 kts.

Mike
 
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