Forum: F-16 Design & Construction

Let's say that you are in a gigantic furball with 67 MiGs in your F-16. You've shot down 4 of them with your missiles....both 120s from the tips and the winders off 2 and 8....plus you gunned 2 to death, making you an instant ace. Very Happy

Now, you need to disengage from the fight, and extend, so you can RTB and collect the accolades and free trip to Vegas and whatnot....so you tap the burner but because your wingtip missile rails are empty, your viper is now mach limited to subsonic.....apparently due to excessive wingtip flutter without "junk" hanging out there.

Seriously? Does that sound plausible? They'd produce a fighter that can't fly supersonic unless its carrying weps? What are you supposed to do in the above scenario....not shoot the wingtip missiles in case you have to exceed mach?

Simple Q.....can F-16s fly faster than sound with empty wingtip rails? Don't care how much faster, or anything regarding speeds with various configurations.....just empty rails faster than mach.

Bueller? Bueller?

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Yes they CAN . . . I've seen it done (not the ace in 1 flight part though) . . . now whether or not it has long term negative effects . . . I don't know, let the engineers answer that question . . .

I can absolutely guaranty you the F-16 was allowed to fly as fast with clean tips as with any other loading when it first went into service. And I can't imagine anything has changed that since then. It is true that there is slightly less resistance to flutter with the tips clean, but it is not enough to require lower speed limits.

Can you tell us where such a supposed limit came from?

johnwill wrote:

I can absolutely guaranty you the F-16 was allowed to fly as fast with clean tips as with any other loading when it first went into service. And I can't imagine anything has changed that since then. It is true that there is slightly less resistance to flutter with the tips clean, but it is not enough to require lower speed limits.

Can you tell us where such a supposed limit came from?

No biggie, just settling a point of contention between guys who don't fly F-16s. I think it's been determined that there is a belief that the limit is a reg to reduce fatigue on the tips rather than an absolute physical design limit.

Any viper drivers aware of such a limit? This is the point of contention:

Quote:

Vipers have to carry something on their wingtip launch rails or they will be Mach limited. Basically, a Viper is limited to .8 Mach I believe if you don't hang anything off 1 and 9. You can't go supersonic in a Viper unless you got junk hanging out there.

I think "can't" means "by reg" as opposed to physically can't.

I thought that is why stations 1 and 9 had to have the launchers always on them, so they could fly supersonic with a slick load out? I am a maintainer though.....

double post

Maintainer here also was pretty sure the launchers fit the bill and "not clean". I have seen many incentive rides go out with one rail empty and a dummy on the other. And I haven't heard anyone of not doing mach on their ride that wanted to... Any drivers out there on this one?

Last edited by outlaw162 on Jun 06, 2009 - 01:52 PM; edited 3 times in total

I know nothing about the C model, but for the A model, if for a particular configuration, the mach limit for AIM-9 (any version) employment from the wing-tip launchers was 1.6 (or aircraft config limit), then the mach limit didn't change after employment (the remarks section covering any limitations after employment was empty), so you could still do 1.6 with both empty launchers in that configuration.

Fast is mainly good. Very rarely in the old fighters I flew were you going "too fast".

OL

(jw will probably be surprised I even read that section)

(edit: particular configuration)(PUI)

Probably a question for johnwill: did or would the F-16XL variant need a wingtip round to routinely fly at supersonic?

How did the flutter effect affect the XL? (Or not at all)??

Thanks in advance..

From every experience I've had, when you hang something off the jet your ops limit will
decrease or may stay the same from the bare airframe. Does anyone have any example
at all where an aircraft structural limit would actually increase when something was loaded on
the jet? I'd be surprised (and will learn something new) if that is the case.

I think chandawg and 03fomoco have it right. AfterburnerDecalsScott may have been talking about the requirement for having wingtip launchers for all flight conditions. And that is true, as the launchers are essential for maintaining flutter resistance.

geogen, the XL has the same requirement as all other F-16s, tip launchers must be installed for all flight, but missiles on or off does not matter.

Would the wing tip area flutter if the launchers are removed? This is one of those cases where nobody knows, because there was never any work done to analyze or flight test that configuration. No requirement = no work. Back when Streak Eagle was doing its thing (time to climb records) there was some thought given to going after those records with an F-16, and a set of tip fairings was made to possibly reduce drag, replacing the launchers. But the AF was not about to allow us to possibly embarrass the Eagle, plus it would have taken a lot of work to clear flight without the launchers. So the tip fairings were never flown.

Aircraft Speed/G-limits are in place in case there is another expected flight by that particular airplane. If subsequent flights do not appear likely, there are no Speed/G-limits. If you have a heater heading up your six, don't worry about limits. Very Happy

guardbaby wrote:

Aircraft Speed/G-limits are in place in case there is another expected flight by that particular airplane. If subsequent flights do not appear likely, there are no Speed/G-limits. If you have a heater heading up your six, don't worry about limits. Very Happy

That's where the confusion was.....not supposed to exceed .8 with empty rails as opposed to physically can't exceed .8 with empty rails.

Last edited by chickenlegs on Jun 07, 2009 - 10:50 PM; edited 1 time in total

Remember that all FCF's perform a full speed mach run when accomplished. Unless changes have been made in the last few years, the jet flies clean. Normal configuration for training is usually an inert msl and an ama pod for the flutter. I remember the groans from the op's boys when this came down. There would be no problem getting the heck out of Dodge at full speed if need be. The limits were put in place to address all flying with regards to all scenario's with the exception of having Migs on your butt. At least that's what I remember.
Chickenlegs

I still think you are totally wrong about that. I don't have a -1, but surely someone around here does. Please ckeck the external stores limitation chart in Section 5.

What you are saying is that if you are above 0.8 with one tip missile, you're not allowed to fire it.

Forum: F-16 Design & Construction

F-16 mach number with empty wingtip rails