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Fokker D.VII performance by Mikael Carlson


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#1 =FB=VikS

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Posted 16 August 2011 - 11:40

http://www.youtube.c...d&v=gZZ82xiWP7w" onclick="window.open(this.href);return false;">http://www.youtube.c...atch?feature=pl … ZZ82xiWP7w

By starting procedure - its seems that it had BMW engine?

PS: take a timer and check its roll rate, then compare it with ROF ;)
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#2 ST_ami7b5

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Posted 16 August 2011 - 11:52

Just beautiful!
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#3 Greywing2

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Posted 16 August 2011 - 11:56

well it had mercedes before…dunno if he changed powerplant…
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#4 =FB=VikS

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Posted 16 August 2011 - 11:57

well it had mercedes before…dunno if he changed powerplant…

link?
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#5 Greywing2

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Posted 16 August 2011 - 12:01

http://www.aerodrome...e&id=9&Itemid=7" onclick="window.open(this.href);return false;">http://www.aerodrome...index.php?optio … 9&Itemid=7

well it had mercedes before…dunno if he changed powerplant…

link?


http://www.aviatorsh...son-sweden-kind" onclick="window.open(this.href);return false;">http://www.aviatorsh...ne.com/aircraft … weden-kind


http://www.youtube.c...player_embedded" onclick="window.open(this.href);return false;"> … r_embedded


http://www.theaerodr...roject-104.html" onclick="window.open(this.href);return false;">http://www.theaerodr...com/forum/repli … t-104.html

so it was/is a Mercedes DIIIa 160 HP
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#6 =FB=VikS

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Posted 16 August 2011 - 12:04

well it had mercedes before…dunno if he changed powerplant…

link?


http://www.aviatorsh...son-sweden-kind" onclick="window.open(this.href);return false;">http://www.aviatorsh...ne.com/aircraft … weden-kind


http://www.youtube.c...player_embedded" onclick="window.open(this.href);return false;"> … r_embedded


http://www.theaerodr...roject-104.html" onclick="window.open(this.href);return false;">http://www.theaerodr...com/forum/repli … t-104.html

aha, its seems that it had D.IIIau installed (horizontal air pump).
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#7 Greywing2

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Posted 16 August 2011 - 12:06

well it had mercedes before…dunno if he changed powerplant…

link?


http://www.aviatorsh...son-sweden-kind" onclick="window.open(this.href);return false;">http://www.aviatorsh...ne.com/aircraft … weden-kind


http://www.youtube.c...player_embedded" onclick="window.open(this.href);return false;"> … r_embedded


http://www.theaerodr...roject-104.html" onclick="window.open(this.href);return false;">http://www.theaerodr...com/forum/repli … t-104.html

aha, its seems that it had D.IIIau installed (horizontal air pump).

some resources said it had DIIIa but yes, according to the engine on the tube film it was DIIIau…..the one you will make….once :-)

here, on "his page" it says it was/it is DIIIa 160 HP (an original one):

http://www.aerodrome...e&id=9&Itemid=7" onclick="window.open(this.href);return false;">http://www.aerodrome...index.php?optio … 9&Itemid=7
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#8 gavagai

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Posted 16 August 2011 - 12:12

Every Mercedes in the Albatros, Pfalz D.III(a), and D.VII was "160hp." Just not all of them were 160hp. ;)

PS: take a timer and check its roll rate, then compare it with ROF ;)

Do we know he was rolling at the maximum rate? What's more intriguing to me is whether its aileron deflection really was asymmetrical the way it is in the game.
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#9 Greywing2

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Posted 16 August 2011 - 12:25

I thought that was a joke gava (roll rate test)….lol
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#10 ImPeRaToR

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Posted 16 August 2011 - 13:10

Vik I think the startup procedure was similar for all planes that had The Bosch Anlassmagnet, I found a brief description for the D.VII procedure:

Um ein unbefugtes Anlassen des Flugzeugs zu vermeiden, konnten sowohl der Schlüssel am Zündschloss, als auch die Kurbel des Anlassmagneten abgezogen werden.
Zum Anlassen wurde zunächst bei ausgeschalteter Zündung der Propeller durchgedreht, was im Motor ein zündfähiges Gemisch erzeugte. Nach dem Einschalten der Zündung erzeugte das Drehen am Anlassmagneten in einem Zylinder einen Funken, der den Motor in Gang setzte. Wenn der Motor lief, dann sorgten dessen Zündmagnete für die notwendige Stromversorgung der Zündkerzen. Das gefährliche Anreißen des Propellers von Hand war bei diesem Anlassverfahren nicht erforderlich.

Like Carlson you only need one person to start the engine. You have to turn the ignition off and rotate the prop to create the right mixture in the cylinders. Then you climb into the cockpit and rotate the crank within the cockpit on the box that say Bosch, this will create the sparks required to start the engine. Once the engine is running the spark plugs will do the sparking.

So starting the Mercedes and BMW engines was a lot safer because nobody was close to them when they ignited, you still had to spin the prop to create the right mixture though.


And of course Mercedes referred to the D.IIIaü engine as D.IIIa, the second engine is in fact a D.IIIaü yet they called it D.IIIa:
http://dl.dropbox.co...uumkammer/1.jpg" onclick="window.open(this.href);return false;">http://dl.dropbox.co...uumkammer/1.jpg
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#11 gavagai

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Posted 16 August 2011 - 13:16

Imp, can you or Jorri post that data for the Dutch D.VII again?
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#12 ImPeRaToR

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Posted 16 August 2011 - 13:22

Image

I also have data from one of the German D.VIIs that was flown post war at the Luftwaffe facility in Lipesk, but the author is mixing up the D.IIIaü and D.IIIaüv on a different page so I am not sure how useful it is. It also gives the same weight for the D.VII and D.VIIF which makes it more dubious.
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#13 ImPeRaToR

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Posted 16 August 2011 - 13:27

Meh here it is anyway:

Image
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#14 MattM

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Posted 16 August 2011 - 14:00

aha, its seems that it had D.IIIau installed (horizontal air pump).
The horizontal air pump is not an indicator for a D.IIIau.

That pump was also used on D.IIIa and it seems like the only reason they replaced the vertical airpump was because it blocked the view.

So a plane with D.IIIau engine could still have a vertical airpump (even though that was probably rare) and a D.IIIa engine could have the horizontal airpump.

The only clear indicator for a D.IIIau was a red colored ring around the engine block, which indicated that the engine was overcompressed. The engine in that video doesn't have that, but then it was restaurated and he probably overpainted the whole engine black and doesn't care for Idflieg regulations. Still, i don't see any way to verify, based on that video alone, wether that engine is overcompressed or not.

Did anyone ask him already?



As for the rollrate, we don't know if he gave full aileron deflection, at what speed he was going etc. I would guess that our D.VII in ROF doesn't roll as well at low speed and tends to stall out and fall down like a wet towel when you pull its nose over the horizon a bit.

Every Mercedes in the Albatros, Pfalz D.III(a), and D.VII was "160hp."
They were rated 160 PS. Sorry for nitpicking. :S!:
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#15 J.j.

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Posted 16 August 2011 - 14:04

Your data is scary, Imperator. It seems that both Fokker DVII in ROF are a little bit off, especillay for climb rates.

PS: mp received, I'm processing it, but it will take me a little time to regroup all my stuff. I'll keep you in touch via Wally.
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#16 ImPeRaToR

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Posted 16 August 2011 - 14:06

Merci beaucoup :)
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#17 MiG-77

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Posted 16 August 2011 - 14:28

Your data is scary, Imperator. It seems that both Fokker DVII in ROF are a little bit off, especillay for climb rates.

Actually D.VIIF fits quite well RoF perfomance and other published data. Key is "with/without" altitude throttle.
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#18 MiG-77

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Posted 16 August 2011 - 14:35



By starting procedure - its seems that it had BMW engine?

PS: take a timer and check its roll rate, then compare it with ROF ;)

http://www.youtube.c...&feature=relmfu" onclick="window.open(this.href);return false;"> … ure=relmfu

Does this mean D.Va roll rate is slowered now? ;)
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#19 SYN_Vander

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Posted 16 August 2011 - 15:25

Guys, can't we just ask these pilots? I'm pretty sure Mikael wouldn't mind timing a fast roll with a stop watch. He's no doubt just as geeky as we are when it comes to historical aircraft performance… :)

Anyway, typing email now…. :) ….email sent. Let's wait!
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#20 hq_Jorri

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Posted 16 August 2011 - 15:30

I don't have a reason to think the rollrate on the DVII is off. But I do wonder about the adverse yaw. Viks, what kind of maximum aileron deflection angles does the ROF DVII have?
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#21 arjisme

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Posted 16 August 2011 - 15:42

Would be so nice if the sound of the D.Va in RoF would be more like what we hear in that video!
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#22 =FB=VikS

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Posted 17 August 2011 - 09:14

Do we know he was rolling at the maximum rate? What's more intriguing to me is whether its aileron deflection really was asymmetrical the way it is in the game.


NACA Report No.120

Attached File  Aileron_Movement.jpg   44.15KB   318 downloads
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#23 =FB=VikS

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Posted 17 August 2011 - 09:16

Guys, can't we just ask these pilots? I'm pretty sure Mikael wouldn't mind timing a fast roll with a stop watch. He's no doubt just as geeky as we are when it comes to historical aircraft performance… :)

Anyway, typing email now…. :) ….email sent. Let's wait!


Well, i think long time ago someone had a contact with him? (IvanK?).
It would be great if we can get any contact with him and ask about details.

PS: judjung by video - when 1/2loop on vertical + half roll - seems that not only ailerons fully deflected - but also he uses alot of rudder.
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#24 SC/JG_Oesau

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Posted 17 August 2011 - 10:06

Guys, can't we just ask these pilots? I'm pretty sure Mikael wouldn't mind timing a fast roll with a stop watch. He's no doubt just as geeky as we are when it comes to historical aircraft performance… :)

Anyway, typing email now…. :) ….email sent. Let's wait!


Well, i think long time ago someone had a contact with him? (IvanK?).
It would be great if we can get any contact with him and ask about details.

PS: judjung by video - when 1/2loop on vertical + half roll - seems that not only ailerons fully deflected - but also he uses alot of rudder.

Yes it was IvanK, he's over in the UK at the moment but let me bring this thread to his attention and see if he can have a chat with Mikael.
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#25 =FB=VikS

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Posted 17 August 2011 - 10:17

I don't have a reason to think the rollrate on the DVII is off. But I do wonder about the adverse yaw. Viks, what kind of maximum aileron deflection angles does the ROF DVII have?

PS: the same as by NACA docs (we just checkd it).
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#26 catchov

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Posted 17 August 2011 - 10:24

Now THAT is an aeroplane. Beautiful, majestic and she's just a little bit HOT !

Should have an R rating. :? Think of the kids ….
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#27 Feathered_IV

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Posted 17 August 2011 - 11:37

Holy crap! I'd have paid to see that at the cinema.
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#28 gavagai

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Posted 17 August 2011 - 12:42

But is that the only source we have for the asymmetrical deflection? It could be a typo, mixing up 23 and 32. Looking at the other aircraft in the list that have slightly asymmetrical deflection, none come close to 9 degrees difference.

I think it was Imp who pointed out in another thread that Fokker wasn't stupid, and would have readily understood the negative effect of such a design decision.

And I don't know what sources Dale Addink relied on for his D.VII, but the D.VII in Aces High does not seem to have asymmetrical deflection. He would be one of the first to rely on NACA data, fwiw.
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#29 hq_Jorri

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Posted 17 August 2011 - 13:32

Thanks, Viks

Fokker wasn't a very good airplane designer, actually. And his chief designer, who is responsible for the D.VII, was actually not an airplane designer either. He was a welder with no background in airplanes.

He made some of the best airplane designs ever, but while he did this, Fokker left him completely in the dark about new techniques or progress in the industry that was going on outside the Fokker plant. Neither did they do any wind tunnel tests.

Differential ailerons didn't exist yet in those days, so there probably wasn't any knowledge about adverse yaw created by unbalanced ailerons.

So it's entirely believable that they messed it up like this.

And based on the available source (just one), the ROF DVII seems spot on in its roll rate and adverse yaw.

What makes me doubt the source, are the many people online saying and quoting that the DVII was perhaps the first airplane with well balanced controls that flies like a more modern plane. Which completely contradicts the above.
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#30 gavagai

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Posted 17 August 2011 - 13:43

From windsock:

Image
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#31 hq_Jorri

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Posted 17 August 2011 - 13:47

Exactly.

But that's all just a reason to look for another direct source on the aileron maximum deflection angles. Until we do, all that means nothing and the ROF DVII is modeled correctly based on the only available source.
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#32 ImPeRaToR

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Posted 17 August 2011 - 13:55

There is also NACA Report 254

There they measure the distribution of pressure along the wing and ailerons of a D.VII at various angle of attack and aileron deflection.
Now, when they describe the wing and aileron, they do not mention differential ailerons in one word! Surely when they describe how the wings taper and the ailerons have horns they would do that, considering how groundbreaking it would've been.
Another clue, probably more relevant, is that they measure the pressure on the ailerons at the same deflections: +20°, +10°, 0°, -10° and -20°. If you ask me, if the ailerons were differential, it would make a lot of sense to use the relevant deflection pairs for up an down, not this. Since they did measure them seperately a symmetrical deflection seems more likely.
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#33 gavagai

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Posted 17 August 2011 - 13:56

And another anecdote, just to annoy the engineers:

Attached File  DVIIpraise.PNG   75.03KB   490 downloads
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#34 hq_Jorri

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Posted 17 August 2011 - 13:58

It's actually very impressive how ROF models the yaw when rolling, it's certainly well done - especially knowing the ailerons are so badly balanced :)

There's enough reason to look for another direct source. But anything other than that is useless, because if they're going to change them they'll have to know what to change them to.
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#35 ImPeRaToR

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Posted 17 August 2011 - 14:02

If Vanderstok gets a reply from Carlson we could also ask about his ailerons. Question is if he took NACA Report No.120 into consideration or not. Perhaps it is actually physically impossible to have asymetrical aileron travel the way the wing is constructed.
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#36 gavagai

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Posted 17 August 2011 - 14:11

Here's a comparison pic from Aces High:

Attached File  aileron.PNG   818.96KB   479 downloads
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#37 SYN_Vander

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Posted 17 August 2011 - 14:13

How about anecdotal evidence? The Fokker DVII has been flown by many pilots, both German and Allied (they were still produced after the war just to be able to deliver the agreed amount of Fokkers to the Allies!). There must be a lot of accounts/impressions of how they flew. Any excessive adverse yaw and/or slow roll rates would have been noted. So why not gather some quotes? When I get home I'll look up some. I remember there is one from Berthold, but there must be many others.
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#38 SYN_Vander

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Posted 17 August 2011 - 16:03

Mikael already answered this one guys. Looks like the rollrate in RoF is not much off. Now start the quest to find figures for the Alb DV rollrates etc….. :)

Pieter,


The roll rate is what you see stick is full left ,and yes rudder is
always used when rolling. Ailerons have equal movement up and down
nothing else is possible with that design.
Engine is a Daimler High compression 200hp.

Mikael Carlson
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#39 ImPeRaToR

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Posted 17 August 2011 - 16:11

:D

Thanks man!


But how much, 20, 23 or 32°?
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#40 =FB=VikS

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Posted 17 August 2011 - 16:19

I think is hard to measure it, but if we can get a photos of fully deflected ailerons up/down - that would be great.

btw - did Mikael knows about ROF?

PS: getting that video recording in max quality (to grab sound) would be cool too :)
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