Yak nominal speed

[GridiroN]

I can't get the yak to fly faster than 400kph even though it's rated nominal speed at 4000m should be 585kph.

 

-Supercharger is stage 2

-Rpm has been tried at both 2700, 2400, and 2200

-throttle maxed

 

Confused...??

[L3Pl4K]

You see indicated airspeed in your cockpit. https://en.wikipedia.org/wiki/Indicated_airspeed

[GridiroN]

You see indicated airspeed in your cockpit. https://en.wikipedia.org/wiki/Indicated_airspeed

Wut...?

 

I'm not asking where to find the yak's speedometer...

[DD_Arthur]

Wut...?

 

I'm not asking where to find the yak's speedometer...

 

Read the Wiki link.

[GridiroN]

Read the Wiki link.

 

I am now more confused than when I posted this thread. 

[216th_Lucas_From_Hell]

Repeat your test with the HUD airspeed indicator on via the quick missions. That will show you the true airspeed.

 

What results do you get at about 1000m with oil radiators at 60%, water at 80%, MP at 10,5 and RPM 2600, ball centred and elevators trimmed?

[ShamrockOneFive]

I am now more confused than when I posted this thread. 

 

Basically the short version is this.

 

The indicator in the cockpit is going to read your speed as how much air is being pushed into the pitot tube (that collects the airspeed data). Essentially it measures air pressure. It does not give a steady value at different altitudes because air pressure drops as you climb.

 

So the indicator in cockpit is "indicated air speed" which is not the same as your ground speed or "true air speed". So it may read 300kph but you're traveling much faster at high altitude depending on the altitude and the air pressure.

[GridiroN]

Repeat your test with the HUD airspeed indicator on via the quick missions. That will show you the true airspeed.

 

What results do you get at about 1000m with oil radiators at 60%, water at 80%, MP at 10,5 and RPM 2600, ball centred and elevators trimmed?

About 460 kph.

Basically the short version is this.

 

The indicator in the cockpit is going to read your speed as how much air is being pushed into the pitot tube (that collects the airspeed data). Essentially it measures air pressure. It does not give a steady value at different altitudes because air pressure drops as you climb.

 

So the indicator in cockpit is "indicated air speed" which is not the same as your ground speed or "true air speed". So it may read 300kph but you're traveling much faster at high altitude depending on the altitude and the air pressure.

What would be the purpose of that? Any pilot would want to know their real speed, wouldn't they?

[Feathered_IV]

I can't get the yak to fly faster than 400kph even though it's rated nominal speed at 4000m should be 585kph

If you put an Fw-190 in front of it, it will apparently do 590.

[6./ZG26_Klaus_Mann]

Try this link: You HUD shows EAS or Equivalent Airspeed that has already been compensated for Compressibility effects. You Convert from that to TAS, true Airspeed. 

 

http://www.hochwarth.com/misc/AviationCalculator.html

Edited May 16, 2016 by 6./ZG26_Klaus_Mann

[Alkyan]

About 460 kph.

 

What would be the purpose of that? Any pilot would want to know their real speed, wouldn't they?

Any pilot would want to know its real speed but how do you achieve that? The idea of the pitot sonde its to measure the dynamic pressure of air on the wing. This pressure can be linked to speed if you also know the static pressure via Bernoulli equation. All planes, even now measure speed this way. What you have is your speed in regard to the air mass (not the ground) plus some error (density of air change with altitude, measurement error, etc...).

Now the order of magnitude of the error is small and it's definitely not the reason why your yak is lacking 200kmh !

Are you sure that you are not in a i16?

[unreasonable]

About 460 kph.

 

What would be the purpose of that? Any pilot would want to know their real speed, wouldn't they?

 

Yes they would, but computing true air speed (TAS) from indicated air speed depends on altitude, pressure, temperature, speed and position of the pitot tube that measures the airflow; not something that could easily be done by instruments in the 1940s. For navigation, pilots would have to use rules of thumb to get an approximate conversion.

[EAF19_Marsh]

Also, air speed - ie that reported by the ASI - is important for the actual flying part because it tells you what degree of lift your aircraft is generating through the mass of air flowing over the wing (aircraft stall at the same speed at 0 metres or 10,000 metres). Ground speed, OTOH, is more important for navigation.

[Aap]

About 460 kph.

 

What would be the purpose of that? Any pilot would want to know their real speed, wouldn't they?

 

Yes and no. Pilot would want to know his TAS (True Air Speed) for navigation or for example for setting up a bombing run, but IAS (Indicated Air Speed) is important aerodynamically, it is what the speed "feels like", when you do maneuvers like turning or climbing or reaching stall speed.

[JtD]

460 indicated at 4000m is about 570 true (in standard atmosphere).

Edited May 16, 2016 by JtD

[216th_Jordan]

Whar is your Mixture setting? Set it to 100%. RPM too. close canopy, check for flaps, gear, etc. trim out your plane and have another test. Engine performance also varies with different temperatures, lower temperature means higher density and thus more power -> you will go quite a bit faster.

to do a test in standard atmosphere conditions select the autumn map in the Quick mission builder. (15° celsius)

good luck!

[Livai]

-Supercharger is stage 2

 

If you dive fast down you can use Supercharger stage 2 to cooling the engine fast down. If you need power & maximum speed fly every time with Supercharger stage 1. My experience is with Supercharger stage 2 the engine create much more heat if you use it for a normal Level flight to your target with the thinking to save some fuel or to cool the engine down. I use the Supercharger stage 2 only if I dive down.

 

BTW Supercharger stage 2 slow you down and thats exactly your problem why you not get the maximum nominal speed from the Yak

Edited May 16, 2016 by Superghostboy

[216th_Jordan]

If you dive fast down you can use Supercharger stage 2 to cooling the engine fast down. If you need power & maximum speed fly every time with Supercharger stage 1. My experience is with Supercharger stage 2 the engine create much more heat if you use it for a normal Level flight to your target with the thinking to save some fuel or to cool the engine down. I use the Supercharger stage 2 only if I dive down.

 

BTW Supercharger stage 2 slow you down and thats exactly your problem why you not get the maximum nominal speed from the Yak

What?!

Thats some serious nonsense. watch your manifold pressure when you change your supercharger at 2000 and then please explain to me how an engine with more manifolp pressure generates less airspeed. if you overheat, why not put your rpm to 90%, quick fix, little power lost.

[Livai]

What?!

Thats some serious nonsense. watch your manifold pressure when you change your supercharger at 2000 and then please explain to me how an engine with more manifolp pressure generates less airspeed. if you overheat, why not put your rpm to 90%, quick fix, little power lost.

 

I said to him as a warning. Myself I have no problems with Engine Mixture 90 - 100%, RPM to 100%, Supercharger stage 1, Engine Cooling Radiator to 25 - 50% = a solution for all altitude + never had serious overheat problems. Overheat problems I only get if I turn for a long time below 300 km/h. If I stay above 300 km/h I can close the Engine Cooling Radiator much more to gain more combat speed. Supercharger stage 2 I used only for a dive down from 4000m to 500m to my target to slow the plane a little down + a good cooling effect, too

[MadisonV44]

If you put an Fw-190 in front of it, it will apparently do 590.

 

+1 

 

You can put the majority of the plane set in pursuit of a FW, it will be almost the same result because you don't have enough time to launch it (degrading energy) and you will be always catch. Even at sea level ... 

 

As per in-game data ground speed at sea level, engine mode - Emergency is 555 km/h for the FW  but it is degrading so much energy and taking so much time to reach his max speed that I'm almost always catch by the Yaks. Even if we are crossing each other, after a U turn it seems the yaks have a tremendous acceleration to reach the max speed. I think the Yak acceleration vs FW energy consuming / degrading does the difference.    

Edited May 16, 2016 by MadisonV44

[216th_Lucas_From_Hell]

Keep it about the Yak-1 top speed, guys

[BlitzPig_EL]

I said to him as a warning. Myself I have no problems with Engine Mixture 90 - 100%, RPM to 100%, Supercharger stage 1, Engine Cooling Radiator to 25 - 50% = a solution for all altitude + never had serious overheat problems. Overheat problems I only get if I turn for a long time below 300 km/h. If I stay above 300 km/h I can close the Engine Cooling Radiator much more to gain more combat speed. Supercharger stage 2 I used only for a dive down from 4000m to 500m to my target to slow the plane a little down + a good cooling effect, too

 

You are doing it wrong.

 

Really you are.

 

If you are over 2000 meters and not on supercharger 2 you are losing power by being in the first supercharger gear.  This will make you slower.

[JtD]

My in game test:

 

http://forum.il2sturmovik.com/topic/21030-impact-radiator-setting-yak-1-speed/?p=332805

 

At higher altitude, use supercharger gear 2.

[GridiroN]

Now correct me if I'm wrong, but the yak is the only vehicle that does this, correct? Because ask the other planes on the game achieve their rated speeds on the dial.

[Willy__]

 

 

Now correct me if I'm wrong, but the yak is the only vehicle that does this, correct? Because ask the other planes on the game achieve their rated speeds on the dial.

 

Sorry, but you're wrong. 

[GridiroN]

Sorry, but you're wrong. 

 

Ill test some planes tomorrow, because the MiG is the only plane i've come across that seems to have this discrepancy on the speedometer. 

[216th_Jordan]

If you would have read the wiki article you would have seen why it is still normal to have indicated airspeed as reference:

 

"The IAS is an important value for the pilot because it is the indicated speeds which are specified in the aircraft flight manual for such important performance values as the stall speed. These speeds, in true airspeed terms, vary considerably depending upon density altitude. However, at typical civilian operating speeds, the aircraft's aerodynamic structure responds to dynamic pressure alone, and the aircraft will perform the same when at the same dynamic pressure. Since it is this same dynamic pressure that drives the airspeed indicator, an aircraft will always, for example, stall at the published indicated airspeed (for the current configuration) regardless of density altitude or true airspeed.[2]"

[BlitzPig_EL]

Cars have speedometers.

 

Aircraft have Air Speed Indicators.

 

There is a reason that it's called an ASI.

 

You need to stop thinking of aircraft speed as an equivalent to automobile speed.

 

Your speed in the air is different than your speed over the ground, and this difference increases the higher up you fly.

[EAF19_Marsh]

Or to take it to an unrealistic extreme, as the ASI measures air speed rather than aircraft speed by a fixed point, you could be traveling at the speed of light in a vacuum and the ASI would register zero, or at walking pace into a massive headwind and the ASI be hard against the upper stop (though a Yak 1 would clearly not be able to fly in such a theoretical state).

 

This being an instrument from a more humble time in human flight, before people became used to the idea that computers knew the answers and were always correct

[=362nd_FS=RoflSeal]

Right, I get the principles of the difference in indicated and actual. My question on this is therefore:

 

How on earth do you navigate if you can't use the indicated speed in a speed * time = distance calculation?!

You convert it to True Air Speed, rule of thumb is to add 2% for every 1,000ft

Edited May 17, 2016 by RoflSeal

[216th_Lucas_From_Hell]

In simple terms, you roughly calculate the true airspeed and then apply Speed * Time = Distance. When wind is a factor, you get the ground airspeed (vector sum of TAS and wind speed/direction) and then do the same as above.

 

True airspeed is also used in bomb sights by level bombers, for example.

 

This file has a table you can refer to: http://www.mission4today.com/index.php?name=Downloads&file=details&id=3727

[Alkyan]

Or to take it to an unrealistic extreme, as the ASI measures air speed rather than aircraft speed by a fixed point, you could be traveling at the speed of light in a vacuum and the ASI would register zero, or at walking pace into a massive headwind and the ASI be hard against the upper stop (though a Yak 1 would clearly not be able to fly in such a theoretical state).

 

This being an instrument from a more humble time in human flight, before people became used to the idea that computers knew the answers and were always correct

This is not a instrument from more humble time it is still used in almost all planes ! A320 uses pitot sonde in the same way than the 109. Of course GPS can give you your ground speed now ! Edited May 17, 2016 by Alkyan

[Scarecrow]

Real pilots are constantly aware of all the physics taking place whilst in flight at all times. I'm pretty sure they call it Basic Airmanship

[VBF-12_Snake9]

Speaking of supercharger and manifold pressure. Don't know what it should be but I know what it is in game. I tested both the lagg and I16. What I fly most.

 

Lagg manifold gets a bump around 2000, but if you switch to super 2 you will lose 13kph. 2500 is the programed alt to change and not lose speed. Tested that alt also. (Specs )

 

I16 manifold gets bump at around 2000 also, but will also lose 10kph at that alt if you switch to super 2. 3000 is the programed alt to change and not lose speed. (Specs ) tested.

 

 

It's clear that the super 2 stages are programed in the game and do not directly relate to the manifold pressure. Do not know why. My assumption was if you increase manifold pressure you should increase speed also. This is in direct contast to my test.

[unreasonable]

 

It's clear that the super 2 stages are programed in the game and do not directly relate to the manifold pressure. Do not know why. My assumption was if you increase manifold pressure you should increase speed also. This is in direct contast to my test.

 

IIRC that is because the stage 2 takes more of the power being produced to run the fan at a higher speed: overall profit/loss of the change in supercharger gear = power produced by higher manifold pressure - power needed to run stage 2.

 

So you have to be high enough for this to be positive before changing gear.  

[VBF-12_Snake9]

I'll buy that.  

 

No need to look at MP, just change gear when the specs say to.  

[EAF19_Marsh]

 

This is not a instrument from more humble time it is still used in almost all planes ! A320 uses pitot sonde in the same way than the 109. Of course GPS can give you your ground speed now !

 

It is an instrument from a more humble time, that does not mean that it has been entirely discontinued not useless. AF447 showed dangers of crew confusion over instrument readouts and over-reliance on particular systems without thinking through what was actually happening.

This is not a instrument from more humble time it is still used in almost all planes ! A320 uses pitot sonde in the same way than the 109. Of course GPS can give you your ground speed now !

 

 

 

It is from a more humble time, I did not say that it is no longer used

 

Tragedies such as AF447 demonstrate that even the most modern onboard systems do not stop people making mistakes.