9g or HMD?
 

Doing a bit of a straw poll, thought I might get a balanced and considered view from the vast wealth of experience that resides within these threads.

In your opinion, consider two aircraft both with the same weapons (ASRAAM, Aim 9X), sensors and signature. Equal in every respect except for the fact that one is capable of say 9g instantaneous and 7g sustained and has a HUD, whereas the other has a HMD (or even just an HMS) and a 7g instantaneous and 5g sustained turn.

Choose your mount.

Be brief, concise and specific.......

Bonus points for working out the minimum turn performance you would accept when taking the HMD against a 9g adversary.

The latter. Let the missile do the work. The HMS technology in the Typhoon for instance should easily win the day. Some modern missiles are capable of 50g turns so 9g ain't going to help very much. Just my 2p.

The fact that an aeroplane has a low g rating does not meannthat it can't go fast and climb well. Concorde had pretty good performance but I doubt it would pull 9g!

Deliverance

RTFQ..... equal in every respect except....

Not just any Aim 9, but Aim 9X, should have kept it simple and just offered ASRAAM

Purely on the BVR shot, both platforms firing at max range and co-speed, the more manoeuvrable has the better chance of reversing after launch to get beyond range of the 'incoming'.

When considering the advantages of an HMD package, it would be wise to await determination of proven capabilities rather than wax lyrical over industry's usual 'Glossy Brochure' claims.

lm

How can a lightningmate (check profile!) even begin to spoll BVR....

Tarnished

Checked profile and even without that handle, instant recognition - by almost anyone I would guess. Hope the sun is not too strong.

I have done other things and at least I use a spell checker :O

lm

lightningmate

spolling quite deliberate (after removing the errant 'g').

Obviously you were never a big fan of The Two Ronnies

Sun v hot, but never get to see it for long, kept in a dark room all day long

Bonus points for bringing up the escape manoeuvre into the argument

Tarnished

You amended the errant 'g' whilst I was responding. Great fan of the Ronnies myself.

lm

Life is never equal. WIWOL Ltg vs Hunter was always a good scrap. Ltg could win above FL250, Hunter below, but mainly a draw providing Ltg remained fast and Hunter turned.

I was foolish enough to fly the T28, thus 2 x T28 vs F14 was fun. If you used USN rules – shoot first; ask questions later, then the F14 won. With USAF rules, ident before fire, then the T28 with a gun was even.

Minimum turn performance you would accept when taking the HMD against a 9g adversary? – assuming all things equal.
Assuming both aircraft turning with the same radius / turn rate and about the same centre, then isn’t the turn rate of the sightline (sightline spin) for the HMS aiming point constant? If so, then for a limiting case of the HMS not being quite on the target, a touch of instantaneous ‘g should help. Then that affects drag, speed, turn, etc, etc, and as I said things are not equal. So a cheap and reliable aircraft with a basic capability to find targets then fire and forget is preferable – providing the politicos agree – but nothing is equal. A good political decision (USN rules) before any engagement is more valuable than ‘g’.

A HMD can also cue you onto targets that are being tracked by other sensors (radar, IRST, co-op, etc) so that you can get eyes-on (VID possibly an ROE constraint?) and increase the chance of a first pass kill. If you start turning you're only setting yourself up for the bandit's wingman - I'll take the HMD.

......but if you put on the brakes....... then he'll fly right by !!

To all 'bad turners' drivers out there, I've never used a HMS, so maybe I don't know nothin' but.... I fly a 9G aircraft. This means that at the merge (assuming you must ID and no shot before merge) after your (less than average turn performance - F3) 90 degrees of turn 2 circle I have already turned 180 and am in your shorts for a mx kill, because the average 3rd gen FJ has 2 x your turn perf. (Draw it) If you can show me where the bad turning jet with HMS has an advantage in this scenario, with ref to angle off, then I eat my words.

Now we're starting to get into the swing of this, more thought less emotion

I was under the impression that the ASRAAM has a significantly greater range the AIM-9X, so it may not be an entirely fair comparison.

I'd be more worried about the min range of my weapon in a VID scenario - how many times have you been 'stuffed' by min range in a 'telephone box' skit, a lot probably (IMHE)?

Ray

- and, IMHO, it's not ALL about 'g' - An F3 at 7g and a Hornet at 7g (both at their respective corner speeds) have very different rates and radii. And then there's the whole 'nose pointing' ability too.....

Its all about the helicopter versus the Starfighter. Helicopter sat hovering in the middle, no speed therefore no g (well 1g) the Starfighter with no wing to speak of rushing round at 500+ knots and if it were strong enough pulling 9g albeit with a small turn rate (deg/sec) and a huge turn radius. Play this same scenario with any range of platforms.

The winning ingredient will always be the aircaft that can pull the highest g at the lowest speed and sustain it. Replace the chopper with an SE5 and t becomes a more understandable argument.

Is this what makes the F3 such a great close in combat aircraft?

Tarnished, and Braveheart have interesting arguments, but I have flown in the past, all flavours! Ideally, you would have both, for just the reasons stated. But, given the choice, I would opt for the HMD solution for 2 reasons:

1. ID comes at very close range, althought a 9 g a/c can 'solve' that problem over time, a HMD linked to a latest generation Mx could do the 'Bizz', 'there and then'.

2. Every fighter pilot, with more than 200 hrs, knows that a turning engagement takes time, and it is rarely the opponent that you are fighting, that is the one that 'Shwacks' you.... so... avoid turning at all costs, at whatever 'g' value.

If you take one posters view of AIM 9x vs ASRAAM, well sadly it's probably a draw. 'Mutal ID Destruction'. At that point 4-6-9-12g or 'Thrust Vectoring' means nothing. (Harrier Mates please don't bother mentioning your 'Lose Control VIFF Manv!!)

Perhaps the prophets of the 60s and 70s who said 'The merge is dead' might well now be right, but late in their assessment.

Only my thoughts.........

Regards,

MW

Tarnished, I beg to differ in the detail: “The winning ingredient will always be the aircraft that can pull the highest ‘g’ at the lowest speed and sustain it.”

Rate of turn is (‘g’ Tan Phi)/speed, thus and as you state, with two different aircraft types, but with identical ‘g’ limits, the type that can sustain the ‘g’ limit at the lowest speed will have the advantage of the higher turn rate.

However, a sustained 7 ’g’ aircraft at 520 TAS generates a RofT of 15 deg/sec, but this is equivalent to a sustained 6 ‘g’ aircraft at 410 TAS, or 4 ’g’ at 270 TAS. Thus, the critical factors are those that enable an aircraft to sustain ‘g’ - the aerodynamics and thrust – and not necessarily the highest ‘g’.

So we need a sustained 4 ’g’ capable SE5a! More thrust, less drag.

Where the objective is to bring a weapon to bear on the target (notwithstanding a fixed bore-sight or an off-axis / HMS), then the rate of turn is the dominant feature. For the extreme and unrepresentative case; the helicopter has a high rate of turn and could align a weapon very quickly; however, a more practical issue would be the rules of engagement, then politics as discussed previously, will be the deciding factor.

Anyway, wasn’t the last war that required a turning fight circa 1976?