Noob question - IAS or TAS -

[ITAF_Civetta]

Sorry guys, I know that is stupid question but I have a doubt: does anometer show IAS or TAS? I think it should be IAS but...

I'm really confused...sometimes, when I flying about 5000m or above, the speed that I can see into cockpit is "strange"...especially when I fly ME410.

 

Please, be patient...eh eh

Edited February 21, 2023 by ITAF_Civetta

[I./JG52_Woutwocampe]

If it would indicate true airspeed, indicated airspeed wouldnt be a thing ;).

Edited February 21, 2023 by I./JG52_Woutwocampe

[Carl_infar]

For true speed, or ground speed You would need data from GPS which obviously wasnt a thing in 1940s

[ITAF_Civetta]

Wait..."True Air Speed" is not "Ground Speed"...

Quote

While ground speed is the airplane’s speed relative to the surface of the Earth, airspeed – at least true airspeed – is its speed relative to the air it is flying in.

In some cases, you can have GS=0 and TAS=700km/h (in a dive of 90° for example) and to calculate TAS you don't need  a GPS: math is enough (and a lot of patient).

 

I need to do some test...maybe with Tacview. 

[AEthelraedUnraed]

1 hour ago, Carl_infar said:

For true speed, or ground speed You would need data from GPS which obviously wasnt a thing in 1940s

That's not true, TAS is different from ground speed (ground speed basically equals TAS + wind speed, both in vector format, and then take its projection onto the 2D space of the ground).

 

IAS differs from TAS depending on altitude; at higher altitudes there's less air pressure in general, so also less air pressure inside the pitot tube and hence a lower indicated speed.

 

That said, @ITAF_Civetta, do you mean specifically an anemometer or an airspeed indicator in general? According to https://riseofflight.com/forum/topic/34617-central-anemometer-true-airspeed/, anemometers like you'll find in most WW1 German aircraft indicate TAS. With some rare exceptions, all other airspeed indicators indicate IAS (e.g. the Me-262 indicates both IAS or TAS depending on airspeed).

[Plurp]

5 hours ago, ITAF_Civetta said:

Sorry guys, I know that is stupid question but I have a doubt: does anometer show IAS or TAS? I think it should be IAS but...

I'm really confused...sometimes, when I flying about 5000m or above, the speed that I can see into cockpit is "strange"...especially when I fly ME410.

 

Please, be patient...eh eh

On Stalingrad autumn map:  410 @ 6000m:  Airspeed indicator = 415, HUD =415 = IAS.  262 @ 6000m:  Airspeed indicator = 562, HUD = 415 = TAS.

[LukeFF]

5 hours ago, ITAF_Civetta said:

Sorry guys, I know that is stupid question but I have a doubt: does anometer show IAS or TAS? I think it should be IAS but...

I'm really confused...sometimes, when I flying about 5000m or above, the speed that I can see into cockpit is "strange"...especially when I fly ME410.

 

Please, be patient...eh eh

 

Yes, the WWI anemometers indicate True Airspeed.

[ITAF_Civetta]

Thanks a lot @Plurpand @LukeFF, really appreciate.

 

Quote

On Stalingrad autumn map:  410 @ 6000m:  Airspeed indicator = 415, HUD =415 = IAS.  262 @ 6000m:  Airspeed indicator = 562, HUD = 415 = TAS.

 

Thanks, you showed me how to clear my doubts. 

[danielprates]

10 hours ago, Carl_infar said:

For true speed, or ground speed You would need data from GPS which obviously wasnt a thing in 1940s

 

Then and now, all it took/takes is to do some math with altitude and temperature, iirc.

[unlikely_spider]

3 hours ago, danielprates said:

 

Then and now, all it took/takes is to do some math with altitude and temperature, iirc.

Or one of these:

[R33GZ]

2 hours ago, unlikely_spider said:

Or one of these:

That's cool man. Is that yours? You have one, just cause?

 

?

[FeuerFliegen]

Many of the answers other than LukeFF's seemed to ignore the fact that your question specifically asked about the anemometer, as opposed to other gauges that give a speed reading.

 

I asked the same thing on the Flying Circus forum because I was confused about the anemometer's reading to be so much higher than what the plane was listed to be capable of with IAS.  I was told that while it's not literally TAS because there could be other forces affecting it so that they are not accurate enough to give a true TAS reading, they will be pretty close to TAS.

[AEthelraedUnraed]

49 minutes ago, SCG_FeuerFliegen said:

Many of the answers other than LukeFF's seemed to ignore the fact that your question specifically asked about the anemometer, as opposed to other gauges that give a speed reading.

 

I asked the same thing on the Flying Circus forum because I was confused about the anemometer's reading to be so much higher than what the plane was listed to be capable of with IAS.  I was told that while it's not literally TAS because there could be other forces affecting it so that they are not accurate enough to give a true TAS reading, they will be pretty close to TAS.

Well, to be frank the OP asks specifically about the anemometer in the Me410. Of course there is no anemometer in the 410, so think it's safe to conclude he's asking about airspeed indicators in general. I did include a link to a topic on the RoF forums that discusses the WW1 anemometers in my reply above though.

[unlikely_spider]

7 hours ago, R33GZ said:

That's cool man. Is that yours? You have one, just cause?

 

?

That one isn't mine, but I do have one! For flight training, you still need to learn how to plot course, arrival times, and fuel consumption using a plotter and flight computer the old way.

 

Nowadays pilots can use Foreflight or Garmin Pilot and it will do these things for you automatically, but flying schools make you learn how to do them manually.

[BlitzPig_EL]

I have a "Whiz wheel" around somewhere.  In IL2 '46 BlitzPig_Raven and I would navigate (well he was the real navigator) off the map, on the Solomon map, to bomb Henderson Field in our H8K " Emily" flying boats.  We would come in from the East at just below contrail altitude.  They never saw us coming.

 

[danielprates]

11 hours ago, unlikely_spider said:

Or one of these:

 

They probably had those in the 40s too, if not that complex.

 

My dad has one, made of alluminium, he bought it when he started flying in 1973. It still looks brand new 50 years later! Current ones are made of disgraceful plastic.

 

Edit: android playstore has an app of it, it advertizes in my local currency but it must be next to us$ 5.00. Worth having as a sim aid. Offttopic but worth mentioning: there is also a paid jeppesen app with outdated jeppesen charts. Outdated so it is unexpensive and not meant for actual flying, but great to use real-life  approach, descent, ascent procedures etc with FSX etc.

Edited February 22, 2023 by danielprates

[LukeFF]

2 hours ago, danielprates said:

Edit: android playstore has an app of it, it advertizes in my local currency but it must be next to us$ 5.00. Worth having as a sim aid. Offttopic but worth mentioning: there is also a paid jeppesen app with outdated jeppesen charts. Outdated so it is unexpensive and not meant for actual flying, but great to use real-life  approach, descent, ascent procedures etc with FSX etc.

 

5 bucks more a month with Navigraph will get you the current Jeppesen charts. ?

[Canvas25]

Free

 

http://ben.com/flying/e6b/

 

 

[danielprates]

A history of the whiz wheel, from wikipedia. I wish it said more about its use in ww2, but it does say 400.000 units where manufactured during the war and that the brits and germans also had their versions:

 

 

.............

The device's original name is E-6B, but is often abbreviated as E6B, or hyphenated as E6-B for commercial purposes.

The E-6B was developed in the United States by Naval Lt. Philip Dalton (1903–1941) in the late 1930s. The name comes from its original part number for the U.S Army Air Corps, before its reorganization in June 1941.

Philip Dalton was a Cornell University graduate who joined the United States Army as an artillery officer, but soon resigned and became a Naval Reserve pilot from 1931 until he died in a plane crash with a student practicing spins. He, with P. V. H. Weems, invented, patented and marketed a series of flight computers.

Dalton's first popular computer was his 1933 Model B, the circular slide rule with true airspeed (TAS) and altitude corrections pilots know so well. In 1936 he put a double-drift diagram on its reverse to create what the U.S. Army Air Corps (USAAC) designated as the E-1, E-1A and E-1B.

A couple of years later he invented the Mark VII, again using his Model B slide rule as a focal point. It was hugely popular with both the military and the airlines. Even Amelia Earhart's navigator Fred Noonan used one on their last flight. Dalton felt that it was a rushed design, and wanted to create something more accurate, easier to use, and able to handle higher flight speeds.

Closeup photo of a cardboard E6B

So he came up with his now famous wind arc slide, but printed on an endless cloth belt moved inside a square box by a knob. He applied for a patent in 1936 (granted in 1937 as 2,097,116). This was for the Model C, D and G computers widely used in World War II by the British Commonwealth (as the "Dalton Dead Reckoning Computer"), the U.S. Navy, copied by the Japanese, and improved on by the Germans, through Siegfried Knemeyer's invention of the disc-type Dreieckrechner device, somewhat similar to the eventual E6B's backside compass rose dial in general appearance, but having the compass rose on the front instead for real-time calculations of the wind triangle at any time while in flight. These are commonly available on collectible auction web sites.

The U.S. Army Air Corps decided the endless belt computer cost too much to manufacture, so later in 1937 Dalton morphed it to a simple, rigid, flat wind slide, with his old Model B circular slide rule included on the reverse. He called this prototype his Model H; the Army called it the E-6A.

In 1938 the Army wrote formal specifications, and had him make a few changes, which Weems called the Model J. The changes included moving the "10" mark to the top instead of the original "60". This "E-6B" was introduced to the Army in 1940, but it took Pearl Harbor for the Army Air Forces (as the former "Army Air Corps" was renamed on June 20, 1941) to place a large order. Over 400,000 E-6Bs were manufactured during World War II, mostly of a plastic that glows under black light (cockpits were illuminated this way at night).

The base name "E-6" was fairly arbitrary, as there were no standards for stock numbering at the time. For example, other USAAC computers of that time were the C-2, D-2, D-4, E-1 and G-1, and flight pants became E-1s as well. Most likely they chose "E" because Dalton's previously combined time and wind computer had been the E-1. The "B" simply meant it was the production model.

The designation "E-6B" was officially marked on the device only for a couple of years. By 1943 the Army and Navy changed the marking to their joint standard, the AN-C-74 (Army/Navy Computer 74). A year or so later it was changed to AN-5835, and then to AN-5834 (1948). The USAF called later updates the MB-4 (1953) and the CPU-26 (1958), but navigators and most instruction manuals continued using the original E-6B name. Many just called it the "Dalton Dead Reckoning Computer", one of its original markings.

Frontside of the military 6B/345

Backside of the military 6B/345

After Dalton's death, Weems^[5] updated the E-6B and tried calling it the E-6C, E-10, and so forth, but finally fell back on the original name, which was so well known by 50,000 World War II Army Air Force navigator veterans. After the patent ran out, many manufacturers made copies, sometimes using a marketing name of "E6-B" (note the moved hyphen). An aluminium version was made by the London Name Plate Mfg. Co. Ltd. of London and Brighton and was marked "Computer Dead Reckoning Mk. 4A Ref. No. 6B/2645" followed by the arrowhead of UK military stores.

During World War II and into the early 1950s, The London Name Plate Mfg. Co. Ltd. produced a "Height & True Airspeed Computer Mk. IV" with the model reference "6B/345". The tool provided for calculation of the True Air Speed on the front side and Time-Speed calculations in relation to the altitude on the backside. They were still in use throughout the 1960s and 1970s in several European Air Forces, such as the German Air Force, until modern avionics made them obsolete