# Thread: can't get speed | Forums

1. no matter what ac I'm using I can get the speed over 200 mph. What is the deal? I've played with the mixture and prop pitch, but no luck....

2. no matter what ac I'm using I can get the speed over 200 mph. What is the deal? I've played with the mixture and prop pitch, but no luck....

5. Fly in straight line (if you don't know how to trim to fly straight without joystick input, just hold steady course with your joystick, don't dive or climb - just fly straight)
6. Don't touch prop pitch, fuel mixture or any other possible CEM control, as you spawn on airfield you are good in most airplanes up to the 3,000m for obtaining max speed
7. Make sure you are running on 110%+WEP (or whatever boost system is there) or at least max throttle settings
8. ...and last but not least; what type of plane are you using?

4. typically a P-51. FYI, I do all of the above....

5. Is this possibly an Indicated Air Speed vs True air speed situation?

IAS= Indicated Airspeed, what the instrument displays

TAS= True Airspeed, the actual speed of the plane through the air. As the air gets thinner (higher altitude) the airspeed indicator reads a lower speed than True air speed.

6. Yep...its the frequent and common IAS versus TAS issue. Thats what it sounds like to me.

zaccari: Its not that you're flying too slow...its that you probably don't quite know what the speed gauge is telling you. Thats perfectly ok as I didn't realize that either till I started playing the sim and wondering the same question.

Basically there are two methods of measuring speed:

Indicated air speed - this is the speed of the air going past your plane

True air speed - the actual distance you're covering based on the ground

These two methods are exactly the same at sea level where the air is dense. As you increase in altitude these numbers diverge until they are significantly apart. At very high altitudes the speed may read only 150mph but you're actually going 400mph (just for example) based on the ground. The air is thin so the measurement in terms of how much air there is differs from that on the ground.

Typically most WWII fighters develop their best power at medium altitude levels where their engine is still effective but the air is thinner so as to provide less resistance. No plane will go its fastest at sea level but its often closer to sea level that the higher numbers register in the first place.

7. <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Indicated air speed - this is the speed of the air going past your plane

True air speed - the actual distance you're covering based on the ground </div></BLOCKQUOTE>

Icefire,
That's too simplistic. IAS is the *effective* air speed, which varies with air density. At altitude, a plane may be moving at 300 mph with respect to the surrounding air molecules (TAS), but the lower density might equate to an *effective* air speed of, say, 200 mph.

IAS is what I always prefer to have displayed because it gives a much more reliable indicator of what my plane is capable of when maneuvering.

TAS is not with respect to the ground, unless the wind speed at the plane's altitude happens to be calm. A head wind or tail wind will subtract from or add to the ground speed, respectively.

8. I'm assuming now that you are new to flying.

Try flying level.

If you can't see how that looks;

Look out to your left or right and see how your wing tip looks to the horizon.

9. <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Lurch1962:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Indicated air speed - this is the speed of the air going past your plane

True air speed - the actual distance you're covering based on the ground </div></BLOCKQUOTE>

Icefire,
That's too simplistic. IAS is the *effective* air speed, which varies with air density. At altitude, a plane may be moving at 300 mph with respect to the surrounding air molecules (TAS), but the lower density might equate to an *effective* air speed of, say, 200 mph.

IAS is what I always prefer to have displayed because it gives a much more reliable indicator of what my plane is capable of when maneuvering.

TAS is not with respect to the ground, unless the wind speed at the plane's altitude happens to be calm. A head wind or tail wind will subtract from or add to the ground speed, respectively. </div></BLOCKQUOTE>
Yes I realize its simplistic but its easier to understand the basics that way. Its like how my old high school science teachers do the basics of atomic theory with everyone thinking that the electrons orbit the nucleus with a nice predictable flat two dimension orbit. Its good enough to begin the understanding until you can get onto the more complex and subtle stuff later.

What you say is absolutely true and I did give a simplified version. To be honest I don't know all of the particulars either but those were the basics that helped me understand so I could progress further. The first thing needed is to convince the person asking the question that this is actually true in the first place...many have trouble making the initial leap. So best to make it soft