Missile skid turns?

[Jim Doyle]

Recently I've been reading about the UK BVRAAM project.

One question really:

Originally it had four mid-fuselage wings for manoeuvrability, now it has
none. This seems a little odd, since it makes sense that the more agile
missile will have a greater number of control surfaces.

Since then I've found that the new design shall use bank and turn at long
range, and in the immediate short term prior to the kill - skid turns. How
do you skid a missile at 2M+? Exhaust deflection? If anyone can explain, I'd
be very grateful!

Cheers,
Jim Doyle

[Orval Fairbairn]

In article >,
"Jim Doyle" > wrote:

> Recently I've been reading about the UK BVRAAM project.
>
> One question really:
>
> Originally it had four mid-fuselage wings for manoeuvrability, now it has
> none. This seems a little odd, since it makes sense that the more agile
> missile will have a greater number of control surfaces.
>
> Since then I've found that the new design shall use bank and turn at long
> range, and in the immediate short term prior to the kill - skid turns. How
> do you skid a missile at 2M+? Exhaust deflection? If anyone can explain, I'd
> be very grateful!
>
> Cheers,
> Jim Doyle
>
>

The missile body at M2+ has enough aerodynamic forces acting on it that
it doesn't need wings. All you have to have is a method of attitude
control.

[Jim Doyle]

"Orval Fairbairn" > wrote in message
.
...
> In article >,
> "Jim Doyle" > wrote:
>
> > Recently I've been reading about the UK BVRAAM project.
> >
> > One question really:
> >
> > Originally it had four mid-fuselage wings for manoeuvrability, now it
has
> > none. This seems a little odd, since it makes sense that the more agile
> > missile will have a greater number of control surfaces.
> >
> > Since then I've found that the new design shall use bank and turn at
long
> > range, and in the immediate short term prior to the kill - skid turns.
How
> > do you skid a missile at 2M+? Exhaust deflection? If anyone can explain,
I'd
> > be very grateful!
> >
> > Cheers,
> > Jim Doyle
> >
> >
>
> The missile body at M2+ has enough aerodynamic forces acting on it that
> it doesn't need wings. All you have to have is a method of attitude
> control.

For the portion of the flight time that it is making distance on it's target
then I guess so. With a decent sized warhead, casing and other gubbins the
thing's going to have one hell of a lot of momentum cracking along, upon
reaching it's target it'll need to be agile to not be spoofed by evasive
action, so how'd you steer it without control surfaces?

[Keith Willshaw]

"Jim Doyle" > wrote in message
...
>

>
> For the portion of the flight time that it is making distance on it's
target
> then I guess so. With a decent sized warhead, casing and other gubbins the
> thing's going to have one hell of a lot of momentum cracking along, upon
> reaching it's target it'll need to be agile to not be spoofed by evasive
> action, so how'd you steer it without control surfaces?
>
>

It has tail control surfaces , it just seems to lack the
mid fuselage wings seen on some other designs

http://www.mod.uk/dpa/projects/bvraam.htm

Keith

[John Carrier]

I saw a test shot of the Agile proof of concept design (stillborn in the
late seventies) that appeared to do a square corner turn. Slow motion had
the wingless missile (used thrust vectoring) at about 120 degrees AOA as it
turned. Most impressive.

R / John

"Jim Doyle" > wrote in message
...
> Recently I've been reading about the UK BVRAAM project.
>
> One question really:
>
> Originally it had four mid-fuselage wings for manoeuvrability, now it has
> none. This seems a little odd, since it makes sense that the more agile
> missile will have a greater number of control surfaces.
>
> Since then I've found that the new design shall use bank and turn at long
> range, and in the immediate short term prior to the kill - skid turns. How
> do you skid a missile at 2M+? Exhaust deflection? If anyone can explain,
I'd
> be very grateful!
>
> Cheers,
> Jim Doyle
>
>

[Jim Doyle]

"Keith Willshaw" > wrote in message
...
>
> "Jim Doyle" > wrote in message
> ...
> >
>
> >
> > For the portion of the flight time that it is making distance on it's
> target
> > then I guess so. With a decent sized warhead, casing and other gubbins
the
> > thing's going to have one hell of a lot of momentum cracking along, upon
> > reaching it's target it'll need to be agile to not be spoofed by evasive
> > action, so how'd you steer it without control surfaces?
> >
> >
>
> It has tail control surfaces , it just seems to lack the
> mid fuselage wings seen on some other designs
>
> http://www.mod.uk/dpa/projects/bvraam.htm
>
> Keith

Cheers Keith. However I think these vanes are used for the bank and turn
corrections at long range, and not the short term agile 'skid' manoeuvres. I
haven't been able to find anything on the latter so'll just guess at it
being a layman's thrust vectoring!

Jim

[Jeb Hoge]

"Jim Doyle" > wrote in message >...
> Recently I've been reading about the UK BVRAAM project.
>
> One question really:
>
> Originally it had four mid-fuselage wings for manoeuvrability, now it has
> none. This seems a little odd, since it makes sense that the more agile
> missile will have a greater number of control surfaces.
>
> Since then I've found that the new design shall use bank and turn at long
> range, and in the immediate short term prior to the kill - skid turns. How
> do you skid a missile at 2M+? Exhaust deflection? If anyone can explain, I'd
> be very grateful!
>
> Cheers,
> Jim Doyle

And to add to this, do all missiles roll to fly with wings in a
horiz/vert (+) attitude or are there some types that fly at in an "X"
attitude? Darn things always are moving so fast that it's hard to
say, but since they obviously can come off the rail or ejectors in
either attitude, I'd assume that there's some sort of correction in
one of the two cases.

[Peter Stickney]

In article >,
(Jeb Hoge) writes:
> "Jim Doyle" > wrote in message >...
>> Recently I've been reading about the UK BVRAAM project.
>>
>> One question really:
>>
>> Originally it had four mid-fuselage wings for manoeuvrability, now it has
>> none. This seems a little odd, since it makes sense that the more agile
>> missile will have a greater number of control surfaces.
>>
>> Since then I've found that the new design shall use bank and turn at long
>> range, and in the immediate short term prior to the kill - skid turns. How
>> do you skid a missile at 2M+? Exhaust deflection? If anyone can explain, I'd
>> be very grateful!
>>
>> Cheers,
>> Jim Doyle
>
> And to add to this, do all missiles roll to fly with wings in a
> horiz/vert (+) attitude or are there some types that fly at in an "X"
> attitude? Darn things always are moving so fast that it's hard to
> say, but since they obviously can come off the rail or ejectors in
> either attitude, I'd assume that there's some sort of correction in
> one of the two cases.

At a guess, I'd say that most post-1960 missiles try to orient
themselves into the 'X' position. in addition to allowing control
surfaces on all 4 wings (or canards or tail controls) to contribute to
the maneuver, you gain a factor of 1.4 in structural strength, since
the lift forces are spread among all 4 wings. As an example, the Nike
Herculese SAM originally started out with a '+' orinetation in flight,
and a 10 G strucural limit. Restringing the control laws to allow an
'X' orientation upped the G limit to 14, without structural
modifications.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

[Orval Fairbairn]

In article >,
(Jeb Hoge) wrote:

> "Jim Doyle" > wrote in message
> >...
> > Recently I've been reading about the UK BVRAAM project.
> >
> > One question really:
> >
> > Originally it had four mid-fuselage wings for manoeuvrability, now it has
> > none. This seems a little odd, since it makes sense that the more agile
> > missile will have a greater number of control surfaces.
> >
> > Since then I've found that the new design shall use bank and turn at long
> > range, and in the immediate short term prior to the kill - skid turns. How
> > do you skid a missile at 2M+? Exhaust deflection? If anyone can explain,
> > I'd
> > be very grateful!
> >
> > Cheers,
> > Jim Doyle
>
> And to add to this, do all missiles roll to fly with wings in a
> horiz/vert (+) attitude or are there some types that fly at in an "X"
> attitude? Darn things always are moving so fast that it's hard to
> say, but since they obviously can come off the rail or ejectors in
> either attitude, I'd assume that there's some sort of correction in
> one of the two cases.

It depends on the missile and its attitude gyro package. As long as it
has track of its attitude, it can roll (Trident C4 and D5 had no roll
control) freely, but body lift is all it takes to make aerodynamic turns.

[Jeff Crowell]

Jim Doyle wrote:
> Cheers Keith. However I think these vanes are used for the bank and turn
> corrections at long range, and not the short term agile 'skid' manoeuvres.
I
> haven't been able to find anything on the latter so'll just guess at it
> being a layman's thrust vectoring!

Hi, Jim.

I'm no missile expert, but I think what's at play here is this:

At long range, the missile makes gentle maneuvers to maintain as
much energy as possible, using body lift to generate angles. Very
little slew is all that's needed at such speeds, the change in air
flow over the body generates lift and thereby changes the flight
path (angles). It's a pretty efficient, low drag way to do business.

At close range, in the terminal phase, where agility (angle
generation) is more important than maintaining energy, the fins
actuate much more aggressively, slewing the missile body past
angles which would just generate body lift, to reorient the
airframe for a different flight path. At this point you are either
bleeding energy off during a coast intercept (like a Phoenix
missile does in long range profile), or depending on a long-burn
motor to keep up your smash.

To me, that would certainly equate to skid turns. Think of a
sprint race car drifting through a turn, versus steering through it.



Jeff