Cruise Configuration / Fuel Saving speed

[iRocco]

Anyone found the optimal cruise / fuel saving speed of the Tomcat? I was searching through the Natops without luck.

[Nexus-6]

Check the latest Fighter Pilot Podcast (

)

 

 

I think they said that "max conserve" was something like 220 knots with the flaps down.

 

 

EDIT: It's at the 13:30 mark.

Edited March 14, 2019 by Nexus-6

[Victory205]

10 units AOA in all configurations...

 

Airspeed will vary with weight, but was 225 to 240 or so. 230 KIAS was used for a good balance IIRC, but 10 units AOA is where you should be.

[Possum]

For max conserve, you want to be just above where the maneuver flaps deploy, which is usually slightly above 10 units. If you’re doing it right, they will start to come down every time you hit a bump. But dont let them deploy, they burn gas. Use your DLC wheel to keep them up if you get a little too slow.

For max range, about 8.5 units.

Edited March 14, 2019 by Possum

[Essah]

I'd say, high and fest without afterburner will get you the best fuel economy, generally holds true for all jet aircraft. It might even be worth it to engage the burner, to accelerate and once you're fast with minimal AoA (and thus minimal drag) you can cut back out of burner and you'll cruise high subsonic with low fuel flow due to the altitude.

[Flamin_Squirrel]

Check the latest Fighter Pilot Podcast (

)

 

 

I think they said that "max conserve" was something like 220 knots with the flaps down.

 

 

EDIT: It's at the 13:30 mark.

 

I can't check now, but are you sure they said flaps down? That doesn't intuitively make sense to me (degreaded lift/drag ratio), although I could be wrong.

[Possum]

I can't check now, but are you sure they said flaps down? That doesn't intuitively make sense to me (degreaded lift/drag ratio), although I could be wrong.

 

Flaps up for max conserve because of the increased the drag.

[Sandman1330]

I'd say, high and fest without afterburner will get you the best fuel economy, generally holds true for all jet aircraft. It might even be worth it to engage the burner, to accelerate and once you're fast with minimal AoA (and thus minimal drag) you can cut back out of burner and you'll cruise high subsonic with low fuel flow due to the altitude.

 

True to a point, drag caused by lift (induced drag) decreases with airspeed (lower AoA), but drag caused by the air friction against the aircraft (parasite drag) increases exponentially with airspeed.

 

You therefore want the airspeed/AoA that gives the lowest total drag, called L/D max. This will not be necessarily at high speed.

 

Edited March 14, 2019 by Sandman1330

[Nexus-6]

I can't check now, but are you sure they said flaps down? That doesn't intuitively make sense to me (degreaded lift/drag ratio), although I could be wrong.

Not 100% sure, no. I had one eye on the forums, and the other on playing with my new Tomcat. I could easily have heard it wrong.

 

Sent from my SM-G930F using Tapatalk

[Flamin_Squirrel]

I'd say, high and fest without afterburner will get you the best fuel economy, generally holds true for all jet aircraft.

 

I don't think that holds true for ANY jet aircraft.

 

[mattag08]

10 units AOA in all configurations...

 

Airspeed will vary with weight, but was 225 to 240 or so. 230 KIAS was used for a good balance IIRC, but 10 units AOA is where you should be.

 

For 15,000', 14900 lbs fuel, 2xAIM-7, 2xAIM-9, 2xFuel Pod:

 

I'm getting 180 KIAS at 10 AOA units. Does that sounds right? Seems really slow. Also, is an AOA unit not the same as 1 degree AOA? The F2 screen shows about 3-4° less AOA than the AOA units indicator in the cockpit.

 

Also, any insight as to what the marks on the AOA indicator mean? there's a square at 5, triangle at 7.5 and a band at 15.

Edited March 18, 2019 by mattag08

[mkosmo]

Also, is an AOA unit not the same as 1 degree AOA? The F2 screen shows about 3-4° less AOA than the AOA units indicator in the cockpit.

 

No.

[Victory205]

That seems very slow. Units or degrees on the info bar?

 

Units do not equal degrees of AOA. The marks are described in NATOPS, 15 is approach reference.

[mattag08]

That seems very slow. Units or degrees on the info bar?

 

Units do not equal degrees of AOA. The marks are described in NATOPS, 15 is approach reference.

10 units, it was showing about 6-7 AOA in F2.

 

I found the NATOPS section, just wasn't searching for the right terms.

Edited March 18, 2019 by mattag08

[Baz000]

In the Navigation training mission that came with the Tomcat module i'm flying at 20k ft at an alpha of 10 as shown in the cockpit AOA tape... Indicated airspeed is showing at 170 kts, surely that can't be right can it? My maneuver flaps also automatically come down.

 

In that mission you have a fully fueled + external tanks Tomcat, no ordinance.

 

Have screenshots to prove what i'm saying including fuel gauge if needed.

[Victory205]

That seems very, very slow. Can you try 230 KIAS at 15,000 feet and see what your AOA shows on the AOA indicator in the cockpit (not the information bar data)?

[Baz000]

Here is what my instruments show when I tried that.

 

Strange the way the airspeed indicator is above 200 KIAS, I couldn't tell what each mark denoted... It wasn't a mark for every 10 KIAS.

 

AOA seems to show a value of 8.0 units

[Baz000]

now the really odd thing is at 20k ft MSL and holding 10 units of AOA in level flight the KIAS drops drastically to around 180 KIAS as seen in my image, also the maneuvering flaps automatically come fully extended I think below 200 KIAS which may be part of the reason for these indications.

 

I could try to manually override them to retract but i'm thinking in the real jet at cruise you guys didn't need to fuss with the maneuvering flaps for cruise.

[Deano87]

now the really odd thing is at 20k ft MSL and holding 10 units of AOA in level flight the KIAS drops drastically to around 180 KIAS as seen in my image, also the maneuvering flaps automatically come fully extended I think below 200 KIAS which may be part of the reason for these indications.

 

I could try to manually override them to retract but i'm thinking in the real jet at cruise you guys didn't need to fuss with the maneuvering flaps for cruise.

 

Just listening to the fighter pilot podcast again and he says "Max E (endurance) was somewhere around 220knots, you'd be sitting there holding the flaps in with your hand, maybe pulling the breakers, the alpha computer circuit brakers."

 

All of that suggests to me they would be holding the manoeuvre flap in (or up) using the thumbwheel or pulling the breaker if that got tiresome to stop the computer trying to extend them. Just my theory though, I'm sure Victory could clarify.

[Victory205]

The fighter puke podcast boys had a lot wrong in the first twenty minutes I listened to. I wondered if they were asleep when they flew the F14, I'm not sure any of them had 1000 hours in it. I had one compressor stall the entire time I flew it. They said the F14A would stall while trying to tank? WTF? Maybe they had bad maintenance or technique. You wanted the engines at Mil or Zone 5 at high alpha, not Mil or Idle as one of the mentioned.

 

I think their heart was with the Hornet

 

With tanks and AA weapons, max conserve was around 225-235. Maneuvering flaps should come out at 10.5 units at medium altitude.

[Baz000]

Maybe that is the problem, is that the maneuvering flaps are coming out too early or something?

[VampireNZ]

During a patrol mission I was AA weapons (4PH,2SP,2SW) and full fuel incl tanks, sitting around 220-230 at 8 units AOA on the indexer @ 20,000', the manoeuvring flaps had just started to extend.

Edited March 20, 2019 by VampireNZ

[Possum]

Maybe that is the problem, is that the maneuvering flaps are coming out too early or something?

 

To truly fly at max conserve, you have to keep the thumbwheel rolled forward to keep them from deploying. Once the deploy, you’ll have to add power to overcome the drag. So, it’s better to fly a few knots above and keep them in.