Going supersonic in the vertical

[museic]

ok so my buddy and I are in a big debate about whether or not if the f18 (or any military jet) can accelerate to the speed of sound in a 90 degree pitch up attitude. Im saying it cannot as this would require an enourmous amount of excess thrust however he claims that he just saw one do it down at sun and fun and left me a rather cruel message letting me know that I'm wrong. so in an attempt to finally get an educated answer I figured I'd just ask the guys that fly them everyday.

The recorded t/w ratio at max gross for the f18 is like .89 yet he claims these numbers are bs and that the gov't dosen't release the real ones. at this point the only way I can see an f18 accelerating to the speed of sound at an absolute vertical attitude is if it's gutted so that it's so light it's possible. please enlighten me

 

[MIDNJAC]

Federal Aviation Regulations prohibit supersonic flight over the continental United States except in designated supersonic corridors (nowhere near Sun n Fun or such an open assembly of persons). Without a doubt, your friend did not see a Hornet go supersonic, in any portion of it's airshow routine, let alone going vertical.

 

[museic]

Federal Aviation Regulations prohibit supersonic flight over the continental United States except in designated supersonic corridors (nowhere near Sun n Fun or such an open assembly of persons). Without a doubt, your friend did not see a Hornet go supersonic, in any portion of it's airshow routine, let alone going vertical.

well he said that the annoucer said it accelerated to .99 mach completely vertical and that if they were aloud to they would have pushed it to mach 1...he also claimed it did it right after t/o.

 

[Swanee]

well he said that the annoucer said it accelerated to .99 mach completely vertical and that if they were aloud to they would have pushed it to mach 1...he also claimed it did it right after t/o.

Your "friend" doesn't know what he is talking about.

 

[Godspeed]

he claims these numbers are bs and that the gov't dosen't release the real ones. at this point the only way I can see an f18 accelerating to the speed of sound at an absolute vertical attitude is if it's gutted so that it's so light it's possible. please enlighten me

He probably confused this:

With this:

Your friend strikes me as the type that would also believe that contrails are actually secret government aircraft sprinkling HIV causing chemicals over its population.

 

[FLY_USMC]

Have you ever seen a picture of a fighter breaking the sound barrier in the vertical? Neither have I....probably answers your question.

Not to say we can't accelerate in the vertical....but you'd have to be pretty light and I'd assume pretty clean as well.

I also find it humerous that none of the initial responses to your question have ever flown the airplane in question....yay for speculation and Wikipedia.

 

[FlyBoyd]

......

 

[MPH]

I seem to remember reading something at Lex's place about an F-22 punching through the number in the vertical.

 

[museic]

acclerating vertical isn't hard to believe at all...all you need is a t/w ratio over 1.00(which alot of military jets have)..what I find it hard to believe is having enough excess thrust to overcome the enourmous amount of parasitic drag that accumulates with high speed flight to the point were you can get to mach 1. not to mention the fact that you would still have a little bit of induced drag since you would be able to maintain a RW in the opposite direction resulting in lift...I guess really you'd have to be light as hell, clean, and an aft cg would definetly help.

 

[MIDNJAC]

From a theoretical standpoint, why would an aft CG help if you were pointed straight up?

 

[Slammer2]

Cant tell you anything about the Hornet but if this is true:

...he claims these numbers are bs and that the gov't dosen't release the real ones...

Then why would they demonstrate it in an airshow? Or was it a slip up on the gov'ts part? :icon_wink

 

[darrylcn]

People like your friend give plane geeks like me a bad name, tell him he's most of the reason I was afraid to post here for so long. I know a lot about airplanes for a civilian but I also know enough not to go around saying shite that makes me look like a know it all. Well except this time.

The specially made left handed F-14 guy thinks that guy's a tool.

 

[museic]

From a theoretical standpoint, why would an aft CG help if you were pointed straight up?

well because if you can maintain speed at any flight attitude your still going to have a low aoa bc you can maintain a relative wind that would be opposite of the direction of flight within a few degrees. assuming your ground speed is zero it would be like cruising except vertically. now this is all assuming that straight and level flight has the same characteristic vertically as it does horizonally which i'm not a fighter pilot so I dont spend much time in the vertical lol...though as far as i'm aware from a theoretical standpoint it makes sense.

however the more i think about it the less sense it makes bc if you can maintain a speed in the vertical, lift really dosent matter bc your thrust is your means of staying aloft...yeah it dosent make sense haha sometimes I over think things, but hey it was a good thought.

 

[museic]

People like your friend give plane geeks like me a bad name, tell him he's most of the reason I was afraid to post here for so long. I know a lot about airplanes for a civilian but I also know enough not to go around saying shite that makes me look like a know it all. Well except this time.

The specially made left handed F-14 guy thinks that guy's a tool.

um yeah about that...

really it dosent take a fighter pilot to explain why it can or cannot, it's an airplane they all fly the same...the only difference is that someone who actually flies it is going to have the final say bc they actually fly it...give me some numbers and i'll crunch some functions and prove it but since I don't own a poh nor do i want to go jail for trying to get one i figured i'd just ask a pilot who flies one.

 

[HeyJoe]

Your "friend" doesn't know what he is talking about.

Nor do a lot of announcers who are just trying to get audience excited and hardly aerospace experts in this type of discussion

you would still have a little bit of induced drag since you would be able to maintain a RW in the opposite direction resulting in lift...I guess really you'd have to be light as hell, clean, and an aft cg would definetly help.

Unloading the aircraft minimizes/eliminates induced drag. It's used all the time to accelerate horizontally, but can be used in vertical axis or any other orientation relative to the earth. Aft CG isn't a player at all.