F-15X: USAF Seems Interested

[element1loop]

You of course realize they don't need them, they are precautionary (and probably for currency and training). One would do.

They also use them as a training tool for both the Tanker and the Fighter. As the Tanker is going to fly 3,000 miles and only refuel once! Hell, they want the experience (training) and the US Government is already paying for the time (i.e. flight)....

That's what I was referring to. Plus it of course depends if F-35A pilots are flying to maximize range, or just to get there quickly.

[Corsair1963]

You of course realize they don't need them, they are precautionary (and probably for currency and training). One would do.

They also use them as a training tool for both the Tanker and the Fighter. As the Tanker is going to fly 3,000 miles and only refuel once! Hell, they want the experience (training) and the US Government is already paying for the time (i.e. flight)....

That's what I was referring to. Plus it of course depends if F-35A pilots are flying to maximize range, or just to get there quickly.

Honestly, many reasons like keeping the F-35 pilots active. As flying for long hours is very fatiguing. You need something to keep you awake....

[mixelflick]

Pretty sure they use modafinil for that. It's an interesting drug. Not a stimulant (which were used plenty prior), but it keeps you alert/sharp for hours and hours.

Modafinil is a controlled substance/prescription only in the U.S.. But it's precursor (Adrafinil) is not. Takes a little longer to kick in (about 40-45 minutes), but you get the same effect.

Fun stuff

[wrightwing]

You can't compare ferry range, with combat radius. It's also important to note that conventional aircraft have a much larger routing penalty, when it comes to radius. If you want to know the theoretical range of an F-35, consider that it can fly 900 miles on 5,000lbs of fuel (it carries >18,000lbs of fuel.) It's safe to say that it's range is significantly more than 1,350 miles.

What's the source on 900miles? The F-35 basing EIS specified a fuel consumption 11.31lbs per nm for A2A config. That's 818km per 5000lbs. That translates into ~3000km range which less fuel reserve is approx 600nm combat radius that LM has posted from day 1. Spud posted the docs some time back. I should still have a copy somewhere which I'll dig up.

The source is an F-35 pilot talking about the amount of fuel it took to fly from Florida, to the Oshkosh airshow. There are other F-35 (prior F-15)pilots that have said the F-35 has more range than an Eagle with external fuel tanks, and by a good margin. The number of refuelings isn't based upon a "need." It's based upon keeping a certain fuel state for emergencies, and for proficiency training.

https://www.aopa.org/news-and-media/all ... ight-stuff

[weasel1962]

The source is an F-35 pilot talking about the amount of fuel it took to fly from Florida, to the Oshkosh airshow. There are other F-35 (prior F-15)pilots that have said the F-35 has more range than an Eagle with external fuel tanks, and by a good margin. The number of refuelings isn't based upon a "need." It's based upon keeping a certain fuel state for emergencies, and for proficiency training.

Thanks for sharing. I have no doubt the F-35A is more fuel efficient than the eagle but by a factor of 2+? What is being claimed is an engine efficiency that is way more fuel efficient by 200% over the previous generation. If one is comparing 25k lbs of fuel (3 tanks) vs 18k lbs of fuel, possibly. But add 9500lbs in the CFTs, there's no range comparison.

Also disagree on the second point. If its 3000nm range, one doesn't need 7 air refuels for a 3000nm transit.

Its smoke and mirrors. I can understand the USAF (and its pilots) pushing for more F-35As, but clearly its PR rather than fact. The F-35A does not have a 3000nm range, not even close.

[Corsair1963]

Question isn't that the F-35A has a 3,000 mile range. It's how the F-35A compares to the F-15C/E/X with a given payload and range.

This claim that the Eagle has superior range and payload either clean or dirty isn't supported by facts. Just another one of the many F-35 misconceptions.

[weasel1962]

We seem to have a difference in definition of what is fact vs claim.

To me, what is fact is when there is a F-15 flight manual that indicates 10.45 lbs per nm fuel burn for optimum long range cruise (with 4 AIM-7s) that translate into 3000+nm range on a 34000 lb fuel load. What is also fact is when the USAF and Boeing being the manufacturer claims range of the same and a combat radius in excess of 1000nm.

To me, what is a claim is when the USAF says that the F-35A has a range of 1200nm, LM briefs in 20 documents all stating a combat radius of 600nm but a poster claiming that all the docs posted by LM and USAF are wrong, based on selective and distorted reading of what pilots have claimed, and stating categorically that the F-35A has a longer combat radius than the F-15 w CFTs.

[weasel1962]

It'd be also fun to see claims of the combat radius of an F-35A lugging 7 x 2000lbers...

[Corsair1963]

We seem to have a difference in definition of what is fact vs claim.

To me, what is fact is when there is a F-15 flight manual that indicates 10.45 lbs per nm fuel burn for optimum long range cruise (with 4 AIM-7s) that translate into 3000+nm range on a 34000 lb fuel load. What is also fact is when the USAF and Boeing being the manufacturer claims range of the same and a combat radius in excess of 1000nm.

To me, what is a claim is when the USAF says that the F-35A has a range of 1200nm, LM briefs in 20 documents all stating a combat radius of 600nm but a poster claiming that all the docs posted by LM and USAF are wrong, based on selective and distorted reading of what pilots have claimed, and stating categorically that the F-35A has a longer combat radius than the F-15 w CFTs.

Most of the original data for the F-35 was wrong and we know that for a fact. Likely because those numbers were "predictions" not hard numbers. To add to that we have first hand accounts from very respected pilots. With first hand experience. So, honestly don't understand what you don't get???

[Corsair1963]

It'd be also fun to see claims of the combat radius of an F-35A lugging 7 x 2000lbers...

As I have posted before the F-35A/C could easily carry 6 - 2,000 lbs JDAMs, 2 - Amraams, and 2- Sidewinders with ease. (well under gross) Hell, it can even go supersonic with that load. While, an F-15E Strike Eagle with just "5" - 2,000 lbs JDAMs, 2- Amraams, and 2-Sidewinders. Plus, Targeting / Nav Pods and External Fuel would be at GROSS! It also has far more drag and suffers much more of a "performance penalty" than the F-35.

F15ELO.jpg (118.45 KiB) Viewed 69784 times

[wrightwing]

The source is an F-35 pilot talking about the amount of fuel it took to fly from Florida, to the Oshkosh airshow. There are other F-35 (prior F-15)pilots that have said the F-35 has more range than an Eagle with external fuel tanks, and by a good margin. The number of refuelings isn't based upon a "need." It's based upon keeping a certain fuel state for emergencies, and for proficiency training.

Thanks for sharing. I have no doubt the F-35A is more fuel efficient than the eagle but by a factor of 2+? What is being claimed is an engine efficiency that is way more fuel efficient by 200% over the previous generation. If one is comparing 25k lbs of fuel (3 tanks) vs 18k lbs of fuel, possibly. But add 9500lbs in the CFTs, there's no range comparison.

Also disagree on the second point. If its 3000nm range, one doesn't need 7 air refuels for a 3000nm transit.

Its smoke and mirrors. I can understand the USAF (and its pilots) pushing for more F-35As, but clearly its PR rather than fact. The F-35A does not have a 3000nm range, not even close.

The number of refuelings aren't based upon the F-35s range. They're based upon safety margins for diverts, loiter, etc..

[wrightwing]

We seem to have a difference in definition of what is fact vs claim.

To me, what is fact is when there is a F-15 flight manual that indicates 10.45 lbs per nm fuel burn for optimum long range cruise (with 4 AIM-7s) that translate into 3000+nm range on a 34000 lb fuel load. What is also fact is when the USAF and Boeing being the manufacturer claims range of the same and a combat radius in excess of 1000nm.

To me, what is a claim is when the USAF says that the F-35A has a range of 1200nm, LM briefs in 20 documents all stating a combat radius of 600nm but a poster claiming that all the docs posted by LM and USAF are wrong, based on selective and distorted reading of what pilots have claimed, and stating categorically that the F-35A has a longer combat radius than the F-15 w CFTs.

Again, you're comparing ferry range of the F-15 vs combat radius of the F-35. The ferry range with 2 CFTSs and 3 EFTs, is longer than the F-35s range. The combat radius with payload, is a lot less than the ferry range, though. Much of the difference is due to routing. An F-15 won't fly the same route/altitude as an F-35, in combat (unless it's completely permissive airspace.)

[weasel1962]

Actually no I'm not. The range of the F-15C with CFTs and 3 tanks isn't very much different w 4 AIM-120s and 4 AIM-9s. The drag of the AAMs don't actually reduce the range as much. What affects combat radius significantly more is when lugging 2000lb-ers e.g. F-15Es.

ANG F-15Cs will fly exactly the same route for CAP as F-35As. I don't see why not. Agree it may be different for A2G for threat avoidance but that's again assuming there's no threat suppression.

The real impact kicks in is when the afterburner kicks in/mil-power and that's both the F-35A shines because of the fuel efficiency and has a disadvantage in terms of TW.

[Corsair1963]

Actually no I'm not. The range of the F-15C with CFTs and 3 tanks isn't very much different w 4 AIM-120s and 4 AIM-9s. The drag of the AAMs don't actually reduce the range as much. What affects combat radius significantly more is when lugging 2000lb-ers e.g. F-15Es.

ANG F-15Cs will fly exactly the same route for CAP as F-35As. I don't see why not. Agree it may be different for A2G for threat avoidance but that's again assuming there's no threat suppression.

The real impact kicks in is when the afterburner kicks in/mil-power and that's both the F-35A shines because of the fuel efficiency and has a disadvantage in terms of TW.

The F-15C/E will have considerably more drag under any similar load than the F-35. Especially, the F-15E Strike Eagle as it will always carry external fuel and usually Nav/ Targeting Pods. This greatly effect not just the performance but the range of the Eagle.

As for the Amraams and Sidewinders not having much drag. Jon Beelsey says otherwise. As he was quoted as saying even Amraams (AIM-120's) have a big impact on performance. When carried externally........

https://youtu.be/96Kx6b7oKA8

[weasel1962]

of course the F-15 has considerably more drag than the F-35. Yet with all the drag of carrying 2 CFTs and 3 tanks, it still reaches 3400nm.

Its a real testament of what PR means. Get a pilot to say the F-35A is magic plane and voila...hook, line, sinker.

Unfortunately for the rest of us, the drag index of a AIM-120 on an F-15 is 1.7 on a CFT station, 2.3 on a wing station and 2.1 for an AIM-9. That has a major impact, all of less than 1% on the range. For comparison, the CFT drag number is 20.1 or a 600 gal tank is 12.2.