Fuel consumption?

[EtherealN]

Why do you repeat this, we already know?

It's only 400km we are talking about, even climbing to 5000m with target at 200km will use lot of fuel.

 

I've flown airliner routes that are about that range. They climb to 7000+ meters altitude specifically to - you guessed it - save fuel. ;)

 

Also, don't forget one aspect of "climbing": yes, while climbing you are spending extra stored energy (fuel) to gain potential energy (altitude). But when you later descend, you are at that stage using some of this potential energy. So don't make the mistake of thinking that fuel expended to climb is "lost" as far as forward flight is concerned. Just make sure to make your future descent a well planned and efficient one.

 

Could be a different version of Su-25?

 

Edit; Aha, could be my mistake 3600L is probably 2835Kg

 

Jet fuel is indeed lighter than water. (As is gasoline, diesel, crude oil, petroleum-based lubricant oil etcetera. :) )

[VapoR]

Is it possible to see what you are referencing for that? I don't say it to second guess you, I would like to see for my own load outs :)

 

Try to find pictures of Su-25's with heavy mixed loadouts anywhere...and good luck. Most combat pictures you will find have the same weapon on only a few of the pylons. Typically these loadouts are rockets or bombs.

 

Would be nice to get some detailed real life tactics documents of some sort to more realistically use this aircraft. Not that it would change the way that the masses on the sim would act...just take a look at how the A-10 guys load theirs (6 mavs, 16 gbu's, whatever).

 

I would love to have a way to limit loadouts from the ME to avoid this stuff.

[Dima89]

Fair point, I would like to stick to realistic load outs really so I try to follow these sort of rules anyway. Sorry to de-rail the topic.

[Dr_Arrow]

Is it possible to see what you are referencing for that? I don't say it to second guess you, I would like to see for my own load outs :)

 

No problem, our AF used SU-25s in the past and I am in contact with technicians and pilots who worked on them and I asked them about loadouts, which were operationally used. Weapon "computer" as well as other things is very simple in Su-25 and you cannot even mix different types of bombs and usually only a single type of weapon was used with fuel tanks on inner pylons, which were nearly always used. Operational loadouts from Afghanistan/Chechnya are also described in the book by Y.Gordon which confirms what I've been told. He even states, there were squadrons which specialized in rocket weapons and some on bombs only.

 

In general, Su-25 can take a lot of ordnance but IRL there are limitations. In operations, simple and relatively light loadouts (at around 1500 kg of load) are/were used. People often load the 25/T with everything possible and then comply that it handles like a pig and has a limited range :)

 

The other thing to remember regarding fuel consumption is that Su-25 sports modified Mig-21 engines without afterburner and is a frontline attack aircraft not very suitable for long range deep strikes, other aircraft are used for this role like Su-24.

[GGTharos]

I think the 25A needs to have its FCS adjusted so it can only use one type of weapon at a time :)

[VapoR]

I would love to see this if it is the case IRL. ED can go ahead and throw us a clickable pit while they're at it... :P

[lmp]

I think the 25A needs to have its FCS adjusted so it can only use one type of weapon at a time :)

 

I don't think only one weapon at a time is possible. But there clearly are some limitations and I would love to know what exactly they are.

 

OT: If anyone's interested, I know what limitations the MiG-29 FCS has in terms of weapon configurations.

[Dr_Arrow]

I don't think only one weapon at a time is possible. But there clearly are some limitations and I would love to know what exactly they are.

 

OT: If anyone's interested, I know what limitations the MiG-29 FCS has in terms of weapon configurations.

 

This means that you can have only one type of bombs (you cannot combine FAB-250 and 500 on the same aircraft), or one type of laser guided missiles or one type of rocket pods. You can however combine bombs, rockets, guided missiles with some limitations.

[MBot]

I used the default mission payload; 2-25L*2, KH-25ML*2, RBK-500*2, B-8MI*2, R-60M*2 .

 

This is indeed a extremely heavy and unlikely loadout. If this is regarding the Cold War Warrior campaign, which is my baby, I would like to mentioned that this is not the loadout I have initially assigned. I have used a standard Su-25 combat loadout of 4*B-8, 2*R-60 and 2*Fuel for most missions. This was for the initial release some years ago, so I am not sure in what ways ED has modified the campaign in the meantime.

[Mobius_cz]

I found this link, where you can see fuel consumption SU-25 vs A-10.

http://www.kamov.net/versus/a-10-vs-su-25/

SU-25 vs A-10

Fuel: 3600 litres vs 4850 litres

Max range: 1350 km vs 1500 km.

 

Quiet interested indeed. I also found that SU-25 fuel consumption is huge.

IMHO if this is game is based on real data...then the reasons why your SU-25 can't fly so far W/O external fuel tanks are.

1. Loadout : already discussed here

2. Engines...

 

A-10 is using turbofan jet engines, they are quiet fuel efficient even at low altitudes and when your throttle is not 100%, they are really efficient.

SU-25 is using turbojet engines, like someone said here, this is engine from MIG-21 W/O afterburner. This engine is NOT fuel efficient at low altitudes. You will burn fuel much faster than A-10 in the same low altitude.

 

If ED is using real data which they includes types of engines, different fuel consumption for different engines and altitudes and ....... This maybe the be reason why we have our fuel tanks empty so fast :D

[GRUNT -Shrek-]

Why not ask the program?

 

I did some research.

- flightplan distance 100km (so approx 240km in total including one go around). Anapa AB directed Krasnodar area, then return to Anapa AB, one go-around.

- full spool up routine, taxi to 04 from N bunker, climb 4,000m en route, descend starts at 35km of initial landing point, one go around, full landing strip and taxi to opposite parking of airfield.

- weather: nice/default, no wind

- loadout: full internal fuel, no externals

- timeframe: rougly 1hr = 60min.

- fuel consumption: 56% = 1587kg

 

seems legit. So I can spend another 1000kg on TOT/payload drag.

 

:book: I did analysis yet, but my conclusions will follow later.:joystick:

 

Stats listed here, comments appreciated:

http://www.shreksquadron.org/documents/su25/fuel.html (most light, no gun, no externals)

http://www.shreksquadron.org/documents/su25/fuel-most-heavy.html (KGMU, Smoke pods)

 

HTH

 

Edited January 16, 2014 by GRUNT -=Shrek=-

[Mobius_cz]

I did some more research and i found this sentence:

 

"Combat range: 750 km (405 nmi, 466 mi)at sea level, 4,400 kg (9,700 lb) weapons and two external tanks"

 

If it is true that probably find the problem. This combat range includes extra fuel to get 750 km in total.

SU-25 has 3600 litres of fuel in internal tanks. For example SU-27 has almost 12 000 litres in internal tanks and uses more fuel efficient turbofan engines (offcoures without afterburning) and the range of SU-27 is 1390 km at sea level. Offcourse fighter vs bomber, you can't compare it. Just see those numbers A-10 - 4850 litres and capable of air refueling, F-15C (max ferry range) almost 31500 litres of fuel (about 7800 in external tanks)

 

Well imho it seems SU-25 has relatively low internal fuel capacity against the other aircraft and plus it has less fuel efficient engines. That's for real life, not for the game.

 

And i know that this is much more complicated than just ammout of fuel and type of engines, but still 2850 kg of fuel is not much.

[Maverick-X]

Complicated is relative, but regarding the engine type, and the design era, these engines aren't only inefficient at low altitude. They are simply inefficient!

 

It's the same problem with the A10, a full loadout with every possible TER fully loaded and (hopefully not) full internal fuel, some guys really dare to wonder why they can't dodge a SAM...

 

So Weaponload adds weight which adds to the fuel consumption, as more lift has to be produced. Produced lift creates drag: C_d = C_0 + k* C_a^2

(C_d is drag, C_0 is zero lift drag, k is a factor regarding wing layout (elliptical lift distributuion [spitfire] is ideal - k=1) and C_a is lift)

 

And then there is the shape of the loadout on the hardpoints, which adds a lot of surface bathed in the air and therefore creates additional drag.

 

So as you see, a heavy loadout extremely affects flight performance. It's not that noticable with the A10, as it has very fuel efficient engines and quite large tanks. I guess (as I don't know it for sure) that the Su25 is usually equiped with at last one pair of ext. tanks. In fact there are many combat aircraft that are usually flown with ext. tanks, as for example the Mirage family, the F15...

Edited February 8, 2014 by Maverick-X

[Talvid]

I've found that 90% power and 80% power both consume about 4.5 kg of fuel per kilometer