Jump to content

Flying Harrier Upside down = 50kts+ speed gain


FoxxyTrotty

Recommended Posts

Messing about the other day in harrier, doing 500 in level flight near the ground, i began to do some slow rolls and noticed the speed began to INCREASE (no change in power).

 

Usually stick ailerons into the airflow adds drag, and slows a plane down, so I investigated further, and found by inverting the aircraft, maintaining level flight, either thrust is drastically increased, or drag is almost zero - so much so, flying the harrier on idle power, inverted, is almost able to maintain level flight.

 

So while this is great news for those short on fuel on the home run, i thought it worth a mention, and i ain't gonna report it with logs and what not, so if someone can do that, or if devs can recreate the issue without logs by just rolling the harrier, either continuously, or stop half way, its be great to fix in future. thx

. . . . . . .

Every module/ map except the dual winged joke.

Link to comment
Share on other sites

No surprise for me. There has been long discussions about the accuracy of the FM in certain conditions. But it was as usual: Razbam's remained silent and at the same time the white knight army beat everything down ("you didn't fly the Harrier in RL, so shut up!")

But even the testimony of a Harrier pilot regarding one issue was worthless (because he didn't provide a trk file, I guess)

 

But hey, it's a blast anyway;)

 

attachment.php?attachmentid=225372&stc=1&d=1579427417

.

.

loads.png.e2a8161b92c95b9b1bf5761208187e40.png


Edited by Cornelius
Link to comment
Share on other sites

Just tested Started at 1.0Gs, Level and 6.5 units, 2500 AGL, My CAS increases while I'm inverted, but I had to hold -1.1Gs and -2.6AOA to maintain level flight. Unloading that much might account for it.


Edited by Wizard_03

DCS F/A-18C :sorcerer:

Link to comment
Share on other sites

This time its closer to -1.0Gs because I did it without stores, what doesn't make sense?

 

That 1.1 means you’re actually pushing your nose up and climbing. Same as if you pull 1.1g while flying straight up.

 

 

Anyway the FM is not complete. Not sure when/if they intend to flash it out but this is just one of the things to add to the list.

Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s

Link to comment
Share on other sites

That 1.1 means you’re actually pushing your nose up and climbing. Same as if you pull 1.1g while flying straight up.

 

 

Anyway the FM is not complete. Not sure when/if they intend to flash it out but this is just one of the things to add to the list.

 

So the speed increase is because I’m unloaded, are you saying that to fly inverted and level, I should be in 1G flight and that’s the problem??

DCS F/A-18C :sorcerer:

Link to comment
Share on other sites

So the speed increase is because I’m unloaded, are you saying that to fly inverted and level, I should be in 1G flight and that’s the problem??

 

To fly inverted and level you should be at -1.0g of course. If you are at 0.9 you are pulling, if you are -1.1 you are pushing. It's just physics.

Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s

Link to comment
Share on other sites

Please see the track the last one is at -1.0Gs more or less, I’m not the best harrier pilot so I’m sure +/- .1Gs is due to me not holding on the VVI on the horizon perfectly. The first time I did it real quick and didn’t save the track anyways, the second time I trimmed it and as long as I’m on the horizon line it’s -1.0Gs and that’s the track I posted.

DCS F/A-18C :sorcerer:

Link to comment
Share on other sites

So the speed increase is because I’m unloaded, are you saying that to fly inverted and level, I should be in 1G flight and that’s the problem??

 

Please see the track the last one is at -1.0Gs more or less, I’m not the best harrier pilot so I’m sure +/- .1Gs is due to me not holding on the VVI on the horizon perfectly. The first time I did it real quick and didn’t save the track anyways, the second time I trimmed it and as long as I’m on the horizon line it’s -1.0Gs and that’s the track I posted.

 

This is a sure bug.

One thing is "unloading", which means you push a little to reduce the AoA which in turn reduces drag, another thing is flying level while inverted.

 

If anything, this causes more drag! To keep level while inverted you need to push the nose higher up in order to reach an AoA at which the upside-down wing can produce enough lift.

Your cross section relative to the incoming air is bigger (like flying slow with high AoA), on top of that your elevators are also deflected, increasing drag further.

Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s

Link to comment
Share on other sites

This is a sure bug.

One thing is "unloading", which means you push a little to reduce the AoA which in turn reduces drag, another thing is flying level while inverted.

 

If anything, this causes more drag! To keep level while inverted you need to push the nose higher up in order to reach an AoA at which the upside-down wing can produce enough lift.

Your cross section relative to the incoming air is bigger (like flying slow with high AoA), on top of that your elevators are also deflected, increasing drag further.

 

But the AOA relative too zero is less then it is while I’m flying right side up and level. So less total AOA (Closer to zero up or down) usually means less drag? And if I have less load on the aircraft as well, it’s gonna go faster? Also unloading means your reducing G on the aircraft. Which in this case, it goes from +1 to -1 all that put together makes it seem like your gonna get an increase in airspeed. Regardless of where the ground is. The unloaded state is apparently canceling out the increased drag resulting in a net increase in airspeed. What we need to determine is: is that the correct behavior for the harrier?

 

I’m not saying it’s not a bug, but let’s figure it out. What’s causing the speed increase, is a problem with the way drag is modeled, or is it an engine issue, ground effect bug..etc. and I’m not saying I don’t believe you either but I’m gonna test the assumption that inverted flight won’t result in a speed increase with the L-39 which is a completed FM and i will report back.


Edited by Wizard_03

DCS F/A-18C :sorcerer:

Link to comment
Share on other sites

After checking with the L-39 I definitely do not see a speed increase while inverted, however I don't see a speed decrease either. Which if we're saying that this is a drag issue I sure should have...I believe it has a symmetrical airfoil though so the drag on the wing while inverted is going to be minimal and It didn't result in a massive AOA change, I have no idea if the harrier has one too. I'm going to see if entry speed has anything to do with it next.

 

 

Edit: So according to the documentation it has a super-critical airfoil, which is generally flatter on top, could we be seeing an effect of this? Because interestingly it seems speed plays a big role in this effect, its very pronounced at high speed, and almost non-existent at low speeds, which to me makes sense since at high speed the engine is providing more thrust requiring less lift from the wings, thus a lower AOA. While at low speed the wings are doing a lot more of the flying and therefore the drag comes into play much more.


Edited by Wizard_03

DCS F/A-18C :sorcerer:

Link to comment
Share on other sites

Wizard, in general, I think you are misunderstanding some basic stuff.

 

There is no such thing as "unloading".

Unloading is a temporay "push" to clean up the airflow over the wings before you pull for a split S or something.

The only other way to truly unload is to fly a parabolic trajectory in which you are actually unloaded (0 g) for a period of time, like this

 

In level flight, whether you fly straight up or inverted, there is always 1g pulling you towards the earth.

If you fly level, upside down, there is still 1g except you, as the pilot, will be hanging upside down and that become -1.0g for you. You are not magically avoiding the force of gravity, the plane still has the same weight and the wings still have to lift that weight.

 

 

Also, what is AoA relative to "zero"?

AoA is the angle between relative wind and the wing. The wing is shaped to produce optimal lift with minimum drag while flying straight up and level at cruise speed.

If you flip the wing upside down you need a lot more AoA to keep that same wing flying, because it is not optimally shaped to fly upside down.

 

Take an Extra 300 on the other hand, it has a symmetrical airfoil, so for that airplane it doesn't make any difference if you fly upside down or not, that wing will behave in the same way straight or inverted. But this is not the case with most airplanes, including the Harrier.

Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s

Link to comment
Share on other sites

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...