How to calculate combat range?

[Snailman 517]

I tried to find something on the forum, but I gave up. Maybe too early, but I though better to ask it...

 

Is there a quick way how to configure aircraft to have a certain range?

 

Fuel capacity is given... so thats costant. Have to tweak the fuel consumption, but how? Anyway how to measure distance?

 

Or just keep flying in a direction and count the time till I crash? :))))

[+Spillone104 553]

That is a good question.

Usually I've seen that most of the stock fighters have an inferior range compared to the "paper" ones of the real counterparts. But, then again I guess that the publicized ranges are obtained with the most optimal flight regime.

 

To tweak the fuel consumption of a jet engine there are some parameters:

TSFCM0=0.800

TSFCM1=1.200

AfterburnerTSFCM0=2.000

AfterburnerTSFCM1=2.317

 

To measure the distance during a mission just look at the Km or NM indicated on the ADF. Select a waypoint and see how distant it is.

[+Dave 2,322]

Combat range is measured based on the payload. Depending on the mission, they may lower the total fuel to accomidate more weapon weight. In that case, it would either tank up when airborne or the mission itself does not involve a long distance.

[Snailman 517]

Thrust specific Fuel Consumption... yep I know what it is. But what M0 and M1 means? Empty plane and at Max weight ?

There is MinFuelFlow for Idle engines...

[+Spillone104 553]

Actually I still don't know if M0 and M1 are idle and full thrust or subsonic - supersonic SFC. These values were introduced in SF2 serie.

[Snailman 517]

Thrust specific already means it is dependant on thrust. So, kg of fuel for every kN of thrust per hour.

I would put my bet on Mach0 and Mach1... but then it is still strange how planes without AB would go over Mach1 to get a M1 value...

Tomcat has AfterburnerTSFCM0 and M1, but many other aircraft have only simple AfterburnerTSFC

 

When I've done with the skins and the other To-Do this and that, I'll make a test with specific fuel amounts, starting from air and from ground.

 

It is important to set the range of new craft, because of campaign usage... where range is vital (Falklands or the case of Yak-38 )

Edited February 25, 2013 by Snailman

[Fubar512 1,350]

TSFC @ M0 is static fuel consumption at full military power (dry)

TSFC @ M1 is fuel consumption in full military power (dry) at Mach 1.0

 

Both those values can usually be found for most powerplants by performing a google search. And, if it's any consolation, most of ThirdWire's values are close, if not spot on. Dave's explanation of your fuel consumption issues is mostly correct.

 

BTW, the Yak-38 had horribly short legs in real life, and was lucky to have a 100 km combat radius at sea,

Edited February 25, 2013 by Fubar512

[+EricJ 4,245]

Going with Fubar512's explanation, you're better parking the deck off the coast and then you might be able to reach across the other side

 

But in all seriousness combat operations in Afghanistan (if it was Dave or Fubar) it got about 50km max range.

Edited February 25, 2013 by EricJ

[Fubar512 1,350]

But in all seriousness combat operations in Afghanistan (if it was Dave or Fubar) it got about 50km max range.

 

That 50 km combat radius in Afghanistan was due to operation from hot, dusty airstrips at high elevations. In sea trials (that were probably conducted just south of the Arctic circle) Forger crews reported a 100 km radius, with just an A2A loadout.

[Snailman 517]

Ah so it IS Mach related value)) My guess was right) Yes, I have such data, no prob.

 

Yak-38... )) long story. Many different data and opinions... Most crucial problems some people used to bitch about were solved after the first tropical tour, and with Yak-38M. Bad reputation remained.... But there are flame wars even between russians themselves :D I don't want another here))

 

What I do accept as fact, that it could take off with full arms (1.5-2 tons) and max fuel from a 300m "long" "mobile runway" without taxiing, loitering and other delay. And for CAS, delay and reaction time is critical. Its pilot who flew it in Operation "Romb", said himself, that the plane was more "economical" than the Su-17, at 50% tanks the Sukhoys were already on bingo fuel. But, no words about combat range indeed. If it is 50 or 100km, with full payload still excellent for the CAS role there.

 

What we should not forget, that, Yak-38 and their service were considered experimental, the "messiah" they were waiting was already under development from 1975 (Object-48, aka. Yak-41)

[Snailman 517]

TSFC @ M0 is static fuel consumption at full military power (dry)

TSFC @ M1 is fuel consumption in full military power (dry) at Mach 1.0

 

Both those values can usually be found for most powerplants by performing a google search. And, if it's any consolation, most of ThirdWire's values are close, if not spot on.

 

Thanks for the declaration!

 

Well I did a test, (of course on Hard Difficulty for Fuel).

Straight flight at 3000 meters.. I flew for almost 15 minutes on 99% thrust at a speed of 0.97M and burned only 750kg....

Stock TSFC values are 0.6 for M0 and 0.78 for M1.

 

But my flight model however, uses 4 engines at the same time (actually 6, but two are fake). Thats twice of the stock AI craft, when at 99% that means I should burn at least 2.40-2.80 alltogether (more than a F-14 tomcat) Where is my mistake in the calculation? Are these units in kilograms or grams?

Edited February 25, 2013 by Snailman

[+EricJ 4,245]

What I do accept as fact, that it could take off with full arms (1.5-2 tons) and max fuel from a 300m "long" "mobile runway" without taxiing, loitering and other delay. And for CAS, delay and reaction time is critical. Its pilot who flew it in Operation "Romb", said himself, that the plane was more "economical" than the Su-17, at 50% tanks the Sukhoys were already on bingo fuel. But, no words about combat range indeed. If it is 50 or 100km, with full payload still excellent for the CAS role there.

 

From a US standpoint no... you'll have CAS going on for hours (most I spent supporting on the ground was seven hours). Given current capabilities and from my experience the Forger would get a sold no in that department. When you got firefights that last hours staying capability counts, and while a good salvo is always good the turnaround time wouldn't net it a vote from the troops. Afghanistan is too unforgiving and those who fought (US and Soviet) can attest that airpower that can stay around a bit longer will always get a thumbs up, so dragging it off topic a bit the Forger was good for something, but close-air support it shouldn't be. Now if we're talking supporting a beachhead I can see it doing it, but not there, not ever.

 

Unless it magically sprouted better fuel tanks and able to loiter for a few hours like the A-10 or Strike Eagle, I stand by my opinion.

Edited February 25, 2013 by EricJ

[Fubar512 1,350]

Are these units in kilograms or grams?

 

kg

[Snailman 517]

kg

 

kg.... per second I suppose... so 2.4 means all my fuel 2750kg should have burned in 1134 seconds. if on full throttle all the way... 19 minutes. Am I right? I guess thats way too much

[Snailman 517]

From a US standpoint no... you'll have CAS going on for hours (most I spent supporting on the ground was seven hours). Given current capabilities and from my experience the Forger would get a sold no in that department. When you got firefights that last hours staying capability counts, and while a good salvo is always good the turnaround time wouldn't net it a vote from the troops.

 

Such ground support comes from a far away airfield, most of the time, but with bigger payload and waits out the opportunity and call. I see your point... It makes sense from that viewpoint. It depends on doctrine and how we understand terms )

I was the one below, praying for Birdie to give me a light, when "gotta smoke".

[Fubar512 1,350]

2.67-2.9 kg/s is an R-29 burn rate. R-28 was capable of pushing the Yak-38 to Mach 0.988 at low level, So it was a powerful, and undoubtedly thirsty, powerplant.

 

15 minutes at 400 kts (a reasonable crusing speed at low altitude) = 100 nm = 185 km absolute range with zero reserve.

[+EricJ 4,245]

Such ground support comes from a far away airfield, most of the time, but with bigger payload and waits out the opportunity and call. I see your point... It makes sense from that viewpoint. It depends on doctrine and how we understand terms )

I was the one below, praying for Birdie to give me a light, when "gotta smoke".

 

hehehe I got you on that one... True it's a big difference where we still had to sometimes wait, but we had other tricks up our sleeve so air support was always greatly appreciated

[Snailman 517]

2.67-2.9 kg/s is an R-29 burn rate. R-28 was capable of pushing the Yak-38 to Mach 0.988 at low level, So it was a powerful, and undoubtedly thirsty, powerplant.

 

15 minutes at 400 kts (a reasonable crusing speed at low altitude) = 100 nm = 185 km absolute range with zero reserve.

 

 

R-29 (Yak41) or R-28 (Yak38) ?

But the values are bad anyway... or I had mistaken... 0.60 per engine is way low. 2x 0.6 for the main engine (2 separate nozzles) + 2x 0.6 for the lift engines (which are always on by my method) so thats 2.4 But still the result is bad.... whats wrong then? In addition, the autopilot uses only 30-40% thrust only to fly at about 750km/h.

Data ini just gives me closer targets, but I get home with 70% fuel...

 

PS.: Just found official data, Yak-38M used 280liters on vertical take off, including engine start and warmup, 260 liters on vertical landing.

 

PS2, Yak-41M

 

R-29V300

 

TSFCM0=0.794

TSFCM1=1.260

AfterburnerTSFC=2.011

 

+ 2 times RD-41 (on by FM)

TSFCM0=0.815

TSFCM1=1.357

 

= 3.974 alltogether when at 90% thrust, also at about M0.95

Edited February 25, 2013 by Snailman

[Fubar512 1,350]

I'll download your modified data, and take a look at the values.

[Snailman 517]

OK, I put the pack together, a day or two. I'm almost done with the skin, already fixed the lod and decal bleed. Thanks in advance!!!

[+Spillone104 553]

The TFSC should not be divided by the number of engines. The "2 engines" or nozzles of the same R-28 have the total thrust already split but they consume the same for half the thrust. Maybe is better to rise a bit the TFSC of the main engine and set to 0 the one of the sustainer so they not drain the tanks in normal flight.

[Snailman 517]

These are the stock data, I have not changed it yet. I was happy with the flyable and playable result ))

I undestand your idea, and it's good. I'll see what value I need first, for the correct consumption, to achieve the range I want, then I distribute that value between the engines.

 

My idea is to use 8 engines, instead of 6.... Two nozzles of the main engine (for exhaust effects' sake), two lift engines, 2 fake lift engines for the exhaust effect in the correct position, and another two fake engines to produce excess fuel consumption when thrustvector controls are active.

 

Original controls from SF2 NA used the lift engines differently, they were fixed position non-vectored engines, where the thrust was controlled by THRUSTVECTOR_CONTROLS. So if you have set thrust vector to 90degs, you also gave 100% thrust to your lift engines. It was a problem controlling thrust on hoover, because lift engines were always on full throttle. It was not a user friendly method. Also, the lift engine exhaust effects were always active, because if the Controls=Thrustvector_controls are active in the ini, it activates the effect anyway. And, at a place where the thrustposition is. The stock Yak-38 had its lift engines in the center of gravity, so there were problems also with balance, but I solved that too.

 

My method uses the thrust_controls for all engines. This provided easier handling, although also had negative effects.

First, the lift engines are fixed ones, and if the main engine thrust vector is not set to 90degs, and the plane makes a salto to the back. Thus the lift engines had to be set to vectored control, too. If you take off conventionally, it gives you unwanted thrust force, until the plane reaches the step on the MachTable, from where I set the thrust to zero.

Second, because of vectored thrust, the exhaust effect had to be removed from them and planted on fake engines which are fixed downwards BUT not thrust vectored so they produce no effect in level flight.

Third, the fuel consumption has doubled because the lift engines are always active even if their thrust output is zero due to altitute or Mach tables. It would not be a problem, because the plane consumes far less fuel than real. So after having the correct values, I will make two extra fake engines, which are vector controlled. This way they will produce thrust percentage equal to the degree of thrust vector, so they will consume horrible amount of fuel but only on hoover mode.

[+Spillone104 553]

[LiftEngine1]

SystemType=JET_ENGINE

ReferenceName=Kolesov RD-38

InputName=THRUST_VECTOR_CONTROL

EngineID=3

HasAfterburner=FALSE

ThrustVectoring=FALSE

SLThrustDry=28671.6

ThrustAngles=0.0,80.0,0.0

ThrustPosition=-0.46,3.359,0.0

ThrottleRate=0.4

NozzleAnimationID=-1

IdleThrottle=0.10

IdleRPM=0.68

IdleNozzle=0.0

CruiseThrottle=0.37

CruiseRPM=0.82

CruiseNozzle=1.0

MilThrottle=0.65

MilRPM=1.00

MilNozzle=1.0

MaxThrottle=0.78

MaxRPM=1.00

MaxNozzle=1.0

AltitudeTableNumData=21

AltitudeTableDeltaX=609.6

AltitudeTableStartX=0.0

AltitudeTableData=1.000,0.952,0.906,0.860,0.816,0.773,0.731,0.691,0.652,0.614,0.578,0.543,0.509,0.477,0.446,0.416,0.388,0.361,0.335,0.303,0.000

DryMachTableNumData=4

DryMachTableDeltaX=0.1

DryMachTableStartX=0.0

DryMachTableData=1.000,0.968,0.948,0.000

MaxInletTemperature=120.0

TSFCM0=0.600

TSFCM1=0.761

MinFuelFlow=0.01

FireSuppression=TRUE

MinExtentPosition=-0.08,-2.79,-0.84

MaxExtentPosition=-0.86,-0.92,-0.06

GasTempMaxRPM=650.0

GasTempIdleRPM=450.0

GasTempChangeRate=5.0

OverheatTemp=800.0

DamageTempDelta=300.0

OilPressMaxRPM=45.0

OilPressIdleRPM=32.0

OilPressChangeRate=0.4

LowOilPress=12.0

LowOilTempDelta=400.0

HasArmor=TRUE

ArmorMaterial=STEEL

Armor[FRONT].Thickness=4

Armor

.Thickness=4

Armor

.Thickness=4

Armor[REAR].Thickness=4

Armor[TOP].Thickness=2

Armor[bOTTOM].Thickness=2

 

In this case you can use the throttle of the lift engine with a different control and keep it still and not vectorable. Like this you will have only an idle lift engine when in horizontal flight and not dependant on the throttle setting of the main engine.

[Snailman 517]

This was the stock, original method... not good. And there is no other decrease-increase type control available. Anyway it would be way too difficult to manually control both main and lift engines. The thrust balance on the real plane was controlled by automatics, and was still very hard to fly...