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Albatros D.Va top speed at sea level 169km/h (+analysis)

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Our Pfalz is doing 165km/hr on the deck not 3000m.

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I'll be reinstalling Asteroids this evening.

 

image.png.e92106f157a7b5d84c23f99d0efc7b85.png

 

Central planes could benefit from the hyperspace button.

 

 

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15 minutes ago, -332FG-Garven said:

Then why doesn't the in game one go that fast at 3000m it is currently much slower.

 

Might I direct you to the opening post of this topic?

 

TL;DR: The British more than likely tested captured machines with 200hp engines which were in service from mid-1918 onward. We don't have those in the sim. It would be nice if we would.

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4 minutes ago, J5_Hellbender said:

 

Might I direct you to the opening post of this topic?

 

TL;DR: The British more than likely tested captured machines with 200hp engines which were in service from mid-1918 onward. We don't have those in the sim. It would be nice if we would.

Quote

What we do know is that the top speed of the Pfalz D.IIIa (similar airframe, same 160/180hp engine) is also listed at 165km/h (103mph), and that its top speed at 3000m(10,000ft) is also 165km/h (102.5mph) — and at 4500m (15,000ft) is 147km/h (91.5mph).

 

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A friend who has flown the Old Rhinebeck Albatross DVa had this to say about it...

 

The albatross is not a fast airplane at all. In fact it looks streamlined and smooth but it's rather doggy. Of course I have only flown the Aerodrome's albatross with a ranger engine but I test flew it with a newly overhauled 200 ranger and even then it was no rocket ship.  The Triplane is faster and much more maneuverable.  

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I have another friend who has 2nd hand knowledge from an Alb D2/D5a pilot who says the D2 is faster than the D5a.  He is going to check and see if they have any specific numbers and can comment on the speed of these planes....of course, I will report back.

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8 minutes ago, Klugermann said:

I got 180 kph @ 25m  in NFF last night.

 

In RoF? Well, yeah, that was the whole 1.034 thing. They basically gave them the “correct” figures for a D.IIIaü engine without adding the actual overcompression mechanic.

 

And if you reached that speed in FC, might I ask on which map, at what temperature and with how many wings still attached to the airframe?

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Don't know the conditions. Also got 178 for the DIII  177 for the Pfalz  189 for the DVII and 187 for the DVIII.

 

Not selling my RoF account anytime soon. Need to speak to Gus re: porting the Me 262 into FC.

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Can anyone with their hands on the DVa say if it flies this way...

 

Quote

From memory the D.VA when we planned on a cross country flight  was about 75kts in the cruise, that was doing about 1250-1300rpm from memory

by the way, 75 kts is about 140kmh

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Your contributions to these conversations via your personal experience and those of your unique contacts is much appreciated, Chill.

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Slight OT, but please perform test flights in winter conditions. I know that the ac engine can run better in cold temps, but I was not aware that FC planes would benefit from it a lot.

While Camel can fly approx 183 kph at ground level (Lapino summer), the speed will increase to 202 kph on winter conditions (Lapino, winter). Also, the Albie can reach almost 180 kph, Pfalz flies with 175, and Dr.I about 173 kph. The SPAD XIII could reach 227 kph! Have not tried the D.VII, Dolphin and SE5a.

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7 minutes ago, 1PL-Lucas-1Esk said:

Slight OT, but please perform test flights in winter conditions. I know that the ac engine can run better in cold temps, but I was not aware that FC planes would benefit from it a lot.

While Camel can fly approx 183 kph at ground level (Lapino summer), the speed will increase to 202 kph on winter conditions (Lapino, winter). Also, the Albie can reach almost 180 kph, Pfalz flies with 175, and Dr.I about 173 kph. The SPAD XIII could reach 227 kph! Have not tried the D.VII, Dolphin and SE5a.

 

All official measurements done by the developers are performed at ISA, which is 15C and 1013.25hPa. You can either create a map with these exact conditions or use Kuban Autumn.

 

Obviously if you're going to lower the temperature and increase the pressure you will get higher readings, but they will be higher for all planes as you also point out.

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227kph in a Spad??

Maybe with a tailwind. I've yet to see anything higher than 215kph at msl post V3.101

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Posted (edited)
1 hour ago, US103_Baer said:

227kph in a Spad??

Maybe with a tailwind. I've yet to see anything higher than 215kph at msl post V3.101

Try a winter map.  Top speed is affected by air temp and pressure.

Edited by -332FG-Garven

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On 6/11/2019 at 6:02 AM, 6./ZG26_Loke said:

I find it to be a heavy aircraft to dogfight in, I had no chance of following the Se.5 in a turn. So I assume it is more a BnZ aircraft, right? 

Hell, no! You're doing something wrong, surely.

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On 6/11/2019 at 3:15 PM, J2_Trupobaw said:


Having to face Brits who kept getting factory-new replacements in the same clapped out patched up plames was one of German pilots complains in forst half of 1918.
 


It was high altitude recon interceptor, optimailsed against fast, high ceiling German recons, not a superiority fighter. In FC it will suffer from BoB Me-262 syndrome (planes it was best at killing are not there).

Quite so.

 

One can hang about at 11 - 15,000 feet all day in the SE5a, but, since no one else comes up there, one has to lower oneself to the level of the proletarian brawling.

 

Which gets sticky, since the SE turns as if it ate Mogadon sandwiches for lunch.

 

Incidentally, I got to just over 19,000 feet, indicated on JG5's server a couple of days ago. Climb rate above 16,000 feet is......sluggish, but the machine remains controllable.

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Posted (edited)

I wanted to briefly discuss what @Klugermann pointed out to me the other day: the Central aircraft speed gauges (anemometer) are not reading indicated airspeed (IAS), but in fact something closer to true airspeed (TAS).

 

To be fair, the way he said it was: "I'm at 2000m and my gauge is indicating 165km/h, it's a rocket ship!"

 

Indeed 165km/h indicated at 2000m is correct for a Fokker D.VII but certainly not for an Albatros D.Va or Pfalz D.IIIa.

 

 

 

I always use the simple gauges when I perform measurements, since that displays IAS no matter what, so I was indeed surprised to see that the anemometer doesn't (measured at around 2000m):

 

D.Va

tEw8yLF.png

 

D.IIIa

rCM2JNT.png

 

D.VII

bIm34z6.png

 

 

 

Apparently this was noticed even in the days of RoF:

 

https://riseofflight.com/forum/topic/34617-central-anemometer-true-airspeed/

 

The thread in itself is in fact a very interesting read about how indicated airspeed (the difference between dynamic and static pressure) and true airspeed (the actual speed of the wing moving through the air) is typically measured using a pitot tube and static port, and how this is then corrected for instrument and position error to obtain IAS, and corrected for pressure altitude and temperature to obtain TAS.

 

 

However, those tiny whirly anemometers actually do display something close to TAS, since they cause no significant friction and in fact don't spin slower in thinner air. This had me quite stumped. There must eventually come a point where there are no longer enough air molecules to actually push the cups, but those are not relevant altitudes for WWI aircraft.

 

Here's a relevant document (NACA report 420)

 

http://naca.central.cranfield.ac.uk/reports/1933/naca-report-420.pdf

 

And the relevant paragraph:

 

7qy55sm.png

 

 

 

This lends even more credence to the theory that airspeed measurements on Central aircraft were indeed made using TAS rather than IAS. At sea level there is no significant difference between the two, but obviously the difference becomes greater as density decreases with altitude and the anemometer remains largely unaffected by this decrease in density.

 

Learn something new every day... And kudos to the devs for actually getting this right.

Edited by J5_Hellbender

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2 hours ago, J5_Hellbender said:

are not reading indicated airspeed (IAS), but in fact something closer to true airspeed (TAS).

In RoF it was also that way.

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Yup. The anemometer-type indicators in RoF and FC should certainly be indicating something close to TAS, if they are realistic. Not hard to see why, if you think about how an anemometer works, spinning up until the dynamic pressure on the two sides (one more streamlined than the other) is equal.  If there were no friction, this would be entirely independent of air density.

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6 hours ago, SP1969 said:

One can hang about at 11 - 15,000 feet all day in the SE5a, but, since no one else comes up there, one has to lower oneself to the level of the proletarian brawling.

 

Unless of course there was some stupid reason for sending someone very high over enemy lines which required avoiding any opposition, or even worse: two people on the very same plane. But why would they want to miss all the fun?

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1 hour ago, AndyJWest said:

If there were no friction, this would be entirely independent of air density.

Friction is a constant factor, you can adjustthe dial acordingly. Every weatherstation (or most) use anemometers and they are rather precise.

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Posted (edited)

.......unless you get ice, then it's a real bummer !!!!

 

Hmmmmmm, I wonder why they stopped using vane driven annenometers 😁

Edited by HagarTheHorrible

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Posted (edited)
31 minutes ago, HagarTheHorrible said:

.......unless you get ice, then it's a real bummer !!!!

 

Hmmmmmm, I wonder why they stopped using vane driven annenometers 😁

 

In some ways, the dynamic/static ratio given by a pitot tube is more useful. Things like the level-flight stall speed and best climb speed are more closely related to pitot-tube IAS than to TAS (at least at WW1 aircraft speeds, where compressibility doesn't become a significant factor). It's a lot easier to run a couple of air lines to the cockpit than to figure out how to read vane RPM remotely though. I suspect it was this along with reliability issues that led to them being dropped, though maybe drag was also a concern.

Edited by AndyJWest

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Posted (edited)

Why do the Allied gauges measure IAS. Aren't they connected to little prop on the strut.

 

Edited by Klugermann

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1 hour ago, Klugermann said:

Why do the Allied gauges measure IAS. Aren't they connected to little prop on the strut.

That litte prop is hooked up to a pump to pressurize the tank. That is that little cylinder behind it, that looks like an R/C aircraft engine. If that one doesn't spin appropriately (like on idle and slow flight) you have to watch the fuel pressure, else your engine might cut out during the approach. Then you use the manual pump to feed some pressure in the tank to get fuel pressure back up. Else, bad. (We don't have any of that simulated in FC, lest RoF.)

 

The Allied gauges are hooked up to a Venturi tube (that thing on the side of your SPAD next to the cockpit for instance) that in essence measures a pressure differential same as the Pitot tube. The Venturi tube however has the drawback of being more prone to icing, same as a carburator. You can read here a nice NACA report onthose instruments.

 

 

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1 hour ago, Klugermann said:

Why do the Allied gauges measure IAS. Aren't they connected to little prop on the strut.

 

 

2 minutes ago, ZachariasX said:

That litte prop is hooked up to a pump to pressurize the tank. That is that little cylinder behind it, that looks like an R/C aircraft engine. If that one doesn't spin appropriately (like on idle and slow flight) you have to watch the fuel pressure, else your engine might cut out during the approach. Then you use the manual pump to feed some pressure in the tank to get fuel pressure back up. Else, bad. (We don't have any of that simulated in FC, lest RoF.)

 

The Allied gauges are hooked up to a Venturi tube (that thing on the side of your SPAD next to the cockpit for instance) that in essence measures a pressure differential same as the Pitot tube. The Venturi tube however has the drawback of being more prone to icing, same as a carburator. You can read here a nice NACA report onthose instruments.

 

 

 

That is correct.

 

However, even if you would use a little propeller to measure the (relative) wind moving through it, because there is a measurable amount of friction and the air is only pushing on it from one side, it would give you something that approximates IAS. In other words, it would windmill depending on the amount of air moving through it. Since the amount of air molecules decreases with altitude, it would spin slower and slower.

 

As @AndyJWest explains very succintly, the vane and cup anemometer is unaffected by air pressure since it is being pushed on both ends and has negligible friction. In other words, it spins depending on the true speed of the air molecules that pass through it. 

 

If you look at the NACA report passage that I highlit, it says so too near the end.

 

 

 

The real "problem" is that TAS is not a useful speed reading for a fighter pilot. There's no real need to know what the speed of the relative wind is, at least not in combat, but it's incredibly useful to know how much air is keeping your wings aloft, since your wing stalls at the same IAS regardless of air density. At high altitude this means that you will stall at a relatively high TAS. However, since our airfields are almost all located at sea level, where the air is very dense and there is virtually no difference between IAS and TAS (in most circumstances), you can use it as an airspeed indicator for takeoff and landing.

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Posted (edited)

IIRC IAS "scales" with air density; as the air gets thinner the TAS figures for stall speed, best climb speed, cruising speed  etc change (you need to go faster through thinner air to produce the same lift), but remain constant for IAS. It's not that important in WW1, but for instrument flying pilot would have to re-calculate the speeds dependent on altitude (which, too, is given as relative, not absolute) and weather. 

I think of IAS as measure of speed-dependent force with which airframe and surrounding air interact with each other - you need the same force on your wings to not stall, or to climb at certain vertical speed, or to reach never-exceed speed force, but at different altitudes this required force is met at different TAS.

OTOH, TAS should be very useful for things like dead reconing navigation (giving the pilot absolute indication of distance travelled, discarding the wind...).

Edited by J2_Trupobaw

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7 hours ago, J2_Trupobaw said:

OTOH, TAS should be very useful for things like dead reconing navigation (giving the pilot absolute indication of distance travelled, discarding the wind...).

Yes.

 

As for flying the aircraft, you look at IAS. However, structural issues as wing flutter are dependent on TAS.

 

@J5_Hellbender, I think I said just that:

8 hours ago, J5_Hellbender said:

the vane and cup anemometer is unaffected by air pressure since it is being pushed on both ends and has negligible friction. 

quoting him „... if there were no friction...“ I then said there really isn‘t much. That‘s all.

 

But be it. In the real world, instruments are usually not that precise on average for subtleties like that to matter much. I don‘t have TacView, but I guess you could use that to find out if the devs made the Anemometer differ slightly from TAS. I wouldn‘t have bothered doing that. We also have compasses that point exactly north, so why the fuss? (An idea for sabotage: make the pistols magnetic. Fun when they are bringing along those in the cockpit.)

 

But thank God times are over where AC designers would mount relevant instruments that far out of the cockpit.

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On 6/18/2019 at 11:21 PM, J2_Trupobaw said:


OTOH, TAS should be very useful for things like dead reconing navigation (giving the pilot absolute indication of distance travelled, discarding the wind...).

 

TAS does not indicate that. For navigation, the wind speed and direction still have to be taken into account.

 

 

Edited by Cynic_Al
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