Fuel Management in the Su-25t

[BBQ]

Just flew zoom's first mission in the mountains--and after making a few passes on the first target--had to RTB because of fuel. Ends up--I didn't make it--by a hair, and tried to land on a road--that is to say, I crashed.

 

1. the "T" version has longer legs--would hate to fly the original!
   
2. how can I calculate how much range I have left/need?
   

[ZoomBoy27]

You can save fuel from the outset by reducing from maximum to 85-91% as soon as you've gained enough altitude with occasional boosts to maximum speed to get over mountains. Also use SHIFT_F(Full flaps down) to give you a quick height boost.

But stripping down and slowing down are the 2 strategies.

 

After Further testing (per 10KM)

Full Loadout @ 100% - 100 kg

Full Loadout @ 90% - 75-80 kg

Stripped @ 100% - 85 kg

Stripped @ 90% - 65-70 kg

GLiding downwards at reduced speed subtract 5-10 kg for 10km

for 100km trip as in my campaign - 200 kg difference in ingress at full throttle versus slower speed. And when you're over the mountains, you can glide downwards at lower throttle for extra savings.

And on egress you can dump your weapons

 

Later on in the campaign you'll be fully outfitted with Fuel tanks and have to deal with that.

[coldcrew]

if you're going far >100KM it's best to add fuel tanks. < 100KM I usually don't but you should always keep track of the guage. at 1000 or less you probably need to start heading home depending on how far you are from base.

[GGTharos]

Additionally you need to cruise at high altitude - that saves a LOT of fuel. You'll need to plan this out a little; it may not be worth it going to 8000m for a 100km trip, but it is worth it on a 200km (one way) trip, as it'll cut down fuel consumption almost by a half (in my experience, anyway)

[SUBS17]

Thats exactly right, you need to adopt a high/low/high profile to hit long distance targets. Only go low when you're in a SAM/ A/A threat enviroment.

[BBQ]

thanks guys--I'll try to incorporate all of the above :)

[169th_Cobra]

so what sort of range can u expect with full main tanks (no external tanks) and a descent payload in the Su-25T?

 

200km round trip with a little bit of loiter doesn't sound quite right. thats an awfully limited aircraft lol.

[GGTharos]

Not much different than a Harrier in that respect though Cobra.

[ZoomBoy27]

so what sort of range can u expect with full main tanks (no external tanks) and a descent payload in the Su-25T?

 

200km round trip with a little bit of loiter doesn't sound quite right. thats an awfully limited aircraft lol.

Full tanks are 3790 kg @ a heavy usage of 90kg/10km or 9kg/km is 420km - round trip with Zero loiter. Now the question is: how long do you need to loiter?

 

In this mission, there is only 3000kg : 1000 to ingress, 1000 for egress, and 1000 for loiter time. With good fuel handling, you can squeeze 100 out of ingress and 200 out of egress.

From my calculations 1.2 to 1.5 minutes per 100kg

 

What do you do with that 1000kg of loiter? 12-15 minutes

If you have full tanks, that's 1800 kg of loiter? 21-27 minutes

 

In flat terrain 12-15 minutes loiter is not bad because you track sooner and hit more frequently.

In this mission (StopReinforcements) you've got narrow valleys, foggy bottoms, and the switchbacks offer varying problems(at lower heights targets are protected by the road-edge + if you do a bombing run, the convoy might change directions between passes). Time OVER target is more limited which means there are more passes. But skilled pilots would not only get more rounds off but Choose better attack paths probably at a much greater height after the AAA and SAM is cleared off.

 

It's borderline whether this is mission is doable for less skilled people. Hmmm, as mission designer I might have to reissue it with more fuel or less targets. For a missionpack it might be OK but as 1st mission of a campaign - not so good.

[MBot]

Not much different than a Harrier in that respect though Cobra.

 

Only that the Harrier is designed to be based just some miles behind the front...

 

 

The limited amount of fuel in the Su-25T is indeed a strange thing and seems to be quite a limitation of the design. A CAS plane is suposed to have good loiter time over the front. Especially the Su-25T with its 16 Vikhr missles that need many passes and a considerable time to be all employed. The basic Su-25 isn't as affected by the limited fuel tough, as this plane is designed to make one pass, employ all its weapons and get the hell out of there ( 1980s european scenario ).

 

After having played the Su-25T in 1.1 for some time now, I come to the conclusion that the Su-25T is quite a poor plane. The simulation of the plane by ED is excellent ( AFM, avionics, 3d model ) and I have great fun flying it, but I think that the plane itselfe looks like a failure. It can take on many roles but isn't outstanding at any of it.

For CAS it lacks loiter time, maneuverability, view and the right weapons. The Vikhr might be a great weapon for a Helo that can hover behind some trees while lasing but for a plane it seems inaporiate. You have to keep running towards your target while supporting your weapon and end up realy close once the Vikhr finaly hits. And then the Su-25T lacks the maneuverability to break away fast from the target. If there are some Stingers around your objective, you are usualy toast. I have read that some people attack with flaps down and speed reduced to 300 km/h to get around that problem. That alone seems to support that a Ka-50 that can hover completly might be the better platfrom for that weapon system. Flying around at 300 km/h doesn't sound like a very save way to move around in the target area...

The Su-25T is great to take out great numbers of lightly defended targets, but it wont last long in a high threat envoirment. I would take the A-10 above the Su-25T anyday ( IRL ).

 

As for the other mission types. The Su-25T seems like a medicore striker and SEAD plane. It has the right weapons to do the job, but it lacks power, speed and maneuverability to do it right.

[GGTharos]

On the other hand, the A-10 can't do strike or SEAD at all. :(

 

You can force the issue, but it's the wrong AC for the job.

 

The 25T can still drop a TV-guided bomb from 20k feet which lets it avoid all the low-level flak. You can CCRP with the 10 from that altitude, but precision is not guaranteed.

 

The 25T has its place, but you're right; better plane needed. Specifically the engines need to be upgraded IMHO, then it would be ok. Upgrade for power if the fuel consumption can stay the same.

[MBot]

You are right, the A-10 can only do one role, but at leas it is very good at it :)

 

The 25T looks like a plane designed for export into small airforces to me. A single plane type, relative cheap that can do many different jobs. Good for a limited war between financial weak oponents ( = against 3rd world countrys or "terrorists" ). Something along the lines of those high-tech upgrades for Hawks. Good avionics suite put into a inferior airframe ( for the job ).

[ZoomBoy27]

...

The limited amount of fuel in the Su-25T is indeed a strange thing and seems to be quite a limitation of the design. A CAS plane is suposed to have good loiter time over the front.

...

In close CAS situations(~ 50km), I've never found the loiter time a problem. I also think a well co-ordinated attack of a flight(rather than just 1 human with so-so AI) increases its value. I think the SU-25T can do 1 small task well. But how many tasks are there in an ingress? More than a few.

[GGTharos]

Yep...both sides could use a dedicated strike aircraft, ie. an F-16 or F-18 or F-15E, vs. something like a MiG-29SMT or Su-27SM or a Su-32/34.

 

Or perhaps something like an F-111 vs. Su-24 could be even more interesting.

[MBot]

Or perhaps something like an F-111 vs. Su-24 could be even more interesting.

 

Now we are talking about real strikers :) The icing on the cake would be a Tornado tough ;) But we had that already many times...

[EvilBivol-1]

On at least one occasion a real Su-25 pilot, posting online, shared the same opinion in regards to the -T's design concept. He found it almost idiotic to fit 16 anti-tank missiles on the thing, when only a few (at most!) can be utilized in a single pass. As if an enemy armored colomn would allow you to do multiple passes.

 

On the other hand, the answer to this lies only partly in the design concept. The other side of it is economic, or financial. The Vihr system is probalby the most cost-effective solution available and so you go with what you have and try to make the best of it.

[MBot]

On at least one occasion a real Su-25 pilot, posting online, shared the same opinion in regards to the -T's design concept. He found it almost idiotic to fit 16 anti-tank missiles on the thing, when only a few (at most!) can be utilized in a single pass. As if an enemy armored colomn would allow you to do multiple passes.

 

Very interesting statement.

 

This is one aspect almost every sim failed to portray correctly while it is such a critical thing in real life. IRL you usualy make one single pass then you head home, as your chances of survival would go down considerable on your following pass. Everyone on the ground is alerted and weapons are made ready. Solder don't walk around with a Stinger on the shoulders and operators of flak guns wont make a 12 hour shift with 100% concetration, so you have surprise on your side on your first pass. But then things change as everyone is alerted.

Yet in the sims we make pass after pass on the same coloumn, pickeling off vehicle after vehicle until everyone is death. But at least after the second pass every soldier on the ground would have picked up a gun and start shooting at you, the SAM operators would have woken up, someone would have run to get additional Stingers from the back of a truck and someone would have called in fighter support.

 

The fact that you can make a second ( and 3rd.. etc. ) attack run without increased risk does disort the realistic representation of A-G combat quite a bit. I think the way most of us fly A-G missions is quite far from realistic because the sim doesn't force you to do so.

[ZoomBoy27]

Very interesting statement.

 

This is one aspect almost every sim failed to portray correctly while it is such a critical thing in real life. IRL you usualy make one single pass then you head home, as your chances of survival would go down considerable on your following pass. Everyone on the ground is alerted and weapons are made ready.

....

What would be the Visible difference in real life Alerted status?

Vehicles start to weave or disperse? Which has it problems in real-life with panicked drivers. That's about it. Maybe some smoke?

If we are talking an anti-infantry strike, alert status is very, very important. Infantry can go to ground like nothing else. With vehicles I don't see that it makes that much difference.

Increase in small arms fire?

Calling in Air support?

 

I think on the 1st pass in the game, the air defences are constantly alert aren't they already? Certainly those guys with the Vulcan guns sure are sharp when you exit your bombing pass.

[coldcrew]

I believe the 25T is an upgrade for the 25, not an entirely new plane from scratch. So in that sense it's amazing what they did with the frame and engines they had to work with

[BBQ]

I recall in "Vipers in the Storm" that F-16's made multiple passes on targets--but perhaps that was a unique situation--with no Iraqui airforce, etc.

[SUBS17]

In real life when convoys are attacked people usually exit the vehicles and try to find cover. Even during WW2 people reacted this way! The only exception is an armored vehicle that has a heavy machine gun which can be used to help put in a screen of bullets in the hope of hitting the aircraft. In a CAS situation the aircraft can make multiple strikes without actually passing over the target area thus eliminating the chances of being hit by IR manpads and flack thanks to weapons like the vhikr and Maverick. BTW the 25T is a good aircraft to fly, its only because its flight model is the only one that appreciates weight of fuel and ordnance that it flys so badly.

[Kula66]

I think part of the problem is that we (simmers) always load ground attack a/c up to the max ... when you see pictures of a/c on RL missions they often have much lower weapon loads ... Harriers with only 1 or 2 bombs. We see airshow pictures loaded up for publicity shots only.

 

The A-10 flys like a dream with 4 Mavs and 4 bombs ... I try and fly the 25 with canon pobs, Vaks, ARMs, AAMs and ECM and wonder why it is a dog!

[MBot]

What would be the Visible difference in real life Alerted status?

Vehicles start to weave or disperse? Which has it problems in real-life with panicked drivers. That's about it. Maybe some smoke?

If we are talking an anti-infantry strike, alert status is very, very important. Infantry can go to ground like nothing else. With vehicles I don't see that it makes that much difference.

Increase in small arms fire?

Calling in Air support?

 

Different alert status' would primary affect air defence units. The higher the alert level, the shorter the reaction time. So a plane attacking a defended ammo dump might get away without getting fired upon at all if it manages to surprise the ground forces with a undedected fast and low ingress. Or perhaps flak would open fire on the egressing aircraft ( a bit of randomisation in how fast units "wake up" ). But if the aircraft turns around for a second pass, it will meet the airdefence on full alert, ready to open fire imetiatly.

 

Now you could argue that this would make ground attack even easier, as currently AD units are always on full alert and we still manage to get the job done. True, but then mission designers would have to adapt and build their missions with generaly stronger air defence. For the first surprise run it wouldn't make much differences ( doesn't matter if you surprise a Shilka or Osa ), but consequently things would be harder.

 

An effect on non AD units could be regarding tank and IFV mounted machine guns. We had a discussion here sometimes ago where it was concluded that tanks and IFVs would not use their MGs to shoot at aircraft, primary to not draw attention. Sounds very plausible to me.

Now imagine a A-10 attacking a convoy, comming around for its 3rd pass. Wouldn't finaly then every MG on every vehicle open fire on that A-10 ? Because then they obviously already have everyones attention.

So ground units with an "extra high" alert level ( under repeted attack ) would open fire with their secondary machine guns.

 

Another important point, small arms fire, you already mentioned. Unfortunatly we don't have this at all ( yet ). But I guess the intesity of small arms fire would increase if the infantry is under repeated attack. If an Su-25 makes attack run after attack run, the soldiers on the ground would point everything that shoots at it.

 

@BBQ

Of course you are right, there are plenty of situations were planes made multiple runs on the same target. I am currently reading Osprey Combat Aircraft 48, featuring the A-7 in Vietnam. It has a very nice introduction describing a FAC supported CAS mission. The FAC let every single A-7 make multiple passes over a long period of time. But on the other hand, the A-7 always stayed above a saftey altitude that kept them out of AAA range.

I think the "one pass" rule manly applies when an attack needs you to enter the engagement zone of know or suspected threats. If you can stay out of the threat zone you can make as many passes as you want if you have air superiority.

[MBot]

I think part of the problem is that we (simmers) always load ground attack a/c up to the max ... when you see pictures of a/c on RL missions they often have much lower weapon loads ... Harriers with only 1 or 2 bombs. We see airshow pictures loaded up for publicity shots only.

 

The A-10 flys like a dream with 4 Mavs and 4 bombs ... I try and fly the 25 with canon pobs, Vaks, ARMs, AAMs and ECM and wonder why it is a dog!

 

Good point ! I read that A-10 over the 1980s europe usualy only had 2 Mavs and the gun loaded, to keep up maneuverability ( =surviveability ).

[Ironhand]

I think part of the problem is that we (simmers) always load ground attack a/c up to the max ... when you see pictures of a/c on RL missions they often have much lower weapon loads ... Harriers with only 1 or 2 bombs. We see airshow pictures loaded up for publicity shots only.

 

The A-10 flys like a dream with 4 Mavs and 4 bombs ... I try and fly the 25 with canon pobs, Vaks, ARMs, AAMs and ECM and wonder why it is a dog!

Most of us fly with far too much hanging off the wings and, usually, fuel. I don't know how many times I've flown a passworded mission and spent most of the ingress dumping unneeded fuel and/or weapons (not necessarily in the -25T, though) just to increase maneuverability.

 

Rich