I've played with many a flight model in a physics-based flight sim. Drag has a pretty large effect on top aircraft speed. And by played, I mean created...

Not so much when your engine/propellor is limitting factor and speed is low (ofcourse we need to stay at realistic drag factors. IE ofcourse medieval castel would not move with same thrust as WWI plane. But example as in this discussion Dr.I and Fokker D.VIII drag difference).

It's true - the Camel is in many ways a Pup with a better engine, just as the LA-5 to the LaGG.

However, the piece of information I want to see is accleration.

I'll hammer around with WWII planes, which, as noted, isn't entirely transferrable as a means of comparison, but we'll look at the LaGG for the example. On paper, it was as fast as many of the airplanes it competed with (including the "friendly" competition within Soviet design houses), but in the air it didn't cut the mustard. The pilots that flew them noted that "once it got up to steam" it was very quick; however, its combat responsiveness was poor. Once the LaGG started losing energy, it simply couldn't regain it as quickly as its peers.

A better engine and some reworking and it returned as the LA-5, which was a very capable and responsive fighter able to compete.

Short wings and fuselage = susceptibility to torque effects of a rotary, and while I'm sure they put as beefy an engine on the DR1 as they could, it's a balancing act. Not enough power and it's too stable; too much and it's too difficult to fly. I've seen a reproduction Camel with original engine in it take off, fly, and return, and it looks to me like they really walked the edge of instability on it.

I haven't seen a DR1, though, so I don't know how closely they balanced them.

At any rate, the WWI engineers were geniuses in my book. Equal time spent on chalkboards and in the work shed, with a huge amount of intuitive engineering based on experience with trial and error. Not a lot of books to go back and reference; and the few they did have were likely to have been a product of the engineers themselves!

I have read no historical accounts, both by German pilots or those written by the enemy that ever mentions the Fokker Dr.I being considered anything but a slow aircraft.

According to German ace Joseph Jacobs: "it is slower than the Albatros D.V, and therefore, of little use to sneak up on the enemy at altitudes."

According to Gerard Leclerc from the Memorial Flight Association, their well-maintained Fokker Dr.I replica flying with a 130 hp Clerget rotary engine barely can maintain 100mph: "The Dr.I triplane was in service at the same time as the SE5a and SPAD, both had quoted speeds in excess of 130 mph, whereas the triplane struggles to make 100 mph, proving it was at a disadvantage to them in all, but a close-turning dogfight. It also suffered a drag penalty in a diving escape, as while it could dive as steeply, it would not be so fast. The wing drag is also apparent on landing when a glide approach, with engine off, would be very steep."

I'd expect the Fokker Dr.I to have a maximum straight-line performance more closely to the Nieuport 17-27 series, biplane designs of less wing area, less weight, and powered by comparable or superior horsepower rotary engines to the Fokker Dr.I. None of the fastest Nieuport "V" Strutters bested 110 mph at seal level.

Finally, to reinforce what I have previously written in this thread about how the Fokker Dr.I had to be managed to successfully engage the enemy, I quote the following from Peter M Grosz and A E Ferko: "The triplane could undoubtedly outmanoeuvre and out-climb any Allied fighter at altitudes below 4,900-6,500 ft (1500-2000 m), although later the Germans considered the Sopwith Camel its equal. On the distaff side, the Dr I was incapable of catching fast-flying de Havilland and Brequet two-seaters, not to mention Allied fighters. Achieving proper firing position depended on stealth and surprise and on the Allied pilot's desire to continue the fight."

FlyRetired, that pretty much sums up my understanding of the Dr I's performance. Agile, good climb, too slow. I would add, rubbish aileron authority but very powerful rudder/elevator too. Having the ailerons on the top wing only must make the roll response a bit strange...

Cheers,

RD.

RocketDog, I always thought your original post here was on the mark.

Cheers to you too!

Dave

Adolf von Tutschek was able to force down both an SE5 and a SPAD XIII intact in early to mid 1918, and was himself killed in a surprise attack where he was attacked from above. Werner Voss was able to fend off 5 or 6 of Britains top SE5 aces for over 10 minutes before finally paying the price for his decision not to climb out of the fight. I think that says it all about the Dr. 1.

The Dr. 1 should be more than capable of competing against the Scout Experimental and the SPAD in RoF because many of the battles will be fairly short, intentional hairballs rather than the more spaced and erratic encounters that were the reality of WW1. The Dr. 1 had no peer in a dogfight but was ultimately made obsolete by the dive and run tactics of the speed and ceiling superior allied machines.

In RoF, as in any game emphasizing the sustained, close-quarter dogfight, the Dr. 1 should be very competitive. I've seen the Dr. 1 fly next to the Mercedes powered Fokker D VII and the Dr. 1 had a far superior climb rate. The Dr. 1 also turns on a dime so I imagine it should carry both a turn radius and climb rate advantage over any other plane it encounters in a turning fight.

I don't think anyone will debate that getting into a close turn fight with a DR1 is really dumb!

The trick is to know when to extend or run away to keep the little bugger from knocking one down!

In the hands of a pilot that really knows how to fly it, the DR1 will certainly be nasty. I doubt that it will be so much in the hands of most flight sim players.

Guys, guys... please when you quote and say Dr.I was SLOW, do not ignore what altitude was it quoted for! Most of the operational rotary engines of the time were slower at altitude than inline engines. These goes for both sides! Camel dedicated to straffing, anyone?

As MiG77 said. Dr.I 'slowness' comes from engine not working good at higher altitudes than from drag. If you check original flight tests with other engines, you can see it is engine limited more than aerodynamically. Wires net up higher drag value on biplane than wireless 3 wings on Dr.I!

As for my guessing on the ROF model? It will be along the lines PeterGrozni presented in his message. The reason why I think it will be like that is the mix of bad research and the holes they have in their physics engine.
I also predict, that Camel will fly easier than N17 in ROF.. for the same reasons... world around

Yes, but as I have said before. "Slow" describes most german planes in 1918.



It very well might have if comparison was between used planes. Oberursel engine worn out much faster than Mercedes engines (becasue reasons said earlier).




Really? R.F.C official figure to N17 is 107mph at altitude of 2km (which is pretty close to Dr.I at same altitude). There is no number for sealevel speed. Also N17 and Dr.I weight difference is only ~25kg. You also can compare to Sopwith Pup ground level speed which was 111,5mph with 80hp Le Rhone.

I think a few things need straightened out before the arguing continues.

What type of airspeeds were being used during WW1? I know many of the planes did not have an airspeed instrument, did the prototype/test version have one? Are the speeds people quoting indicated or true airspeed?

Drag is by far the biggest limiting factor on the airspeed. Remember, every time you double airspeed, the air resistance goes up by a factor of 4.
Just adding more power doesn't make you go much faster, what it does do is increase fuel burn, and increase climb rate. If you have a 100mph airplane using 100hp in cruise, then for the same airplane to go 200mph in cruise it would need 400hp to achieve it.

There are some 200mph airplanes that do that on 65hp, guess what, they are a very clean design.

Why do you think some of the WW1 planes would reach terminal velocity in a dive? They could literally not go any faster straight down, simply from all of the drag.

Doubt the Dr1 would glide very well either. Remember that video of the plane crashing at Old Rhinebeck? Dr1 would probably glide quite a bit steeper than that, as in a worse glide.

About flight models, I'm pretty sure my own Cessna is modeled wrong. The actual performance no where matches the numbers from the Pilot Operating Handbook. The cruise speed is slower than stated, the climb speed is lower than stated, the take off roll is longer than stated, and the fuel burn is higher than stated.
It's got a fresh engine in it too, so no blaming a old worn out engine.

Clearly Cessna engineers didn't know what they were doing. They had the book to go by, and still screwed it up. The cruise speed is off by about 15kts, the climb speed is off by a couple hundred feet per minute, and the take off roll is off by a few hundred feet too. There is just no excuse for the half assed effort put into the flight model of my Cessna. I demand my next Cessna to be FREE! Damnit!

I havent readed what the method was, but I think it is safe to say those are true airspeed (as speed decreases as they go higher and most engines gave best power output at ground level).



Yes, but as I said earlier more important was engine and probellor (in max level speed) as all WWI planes could reach probellor max efficiency speed. After it you would not gain "extra thrust" that much. Also if talking about WWI you cannot even talk about "clean desings". All of them were draggy compared to more modern ones In the end effect is that more clener desing will accelerate faster, but it will hit to same probellor/engine limit as more draggier desing (It would be only slightly faster).

More plane speed to compare:

"Draggy" Sopwith triplane (with 110hp Le Rhone):

• 
  
  ground lvl 121mph
  6500ft 111,5mph
  10000ft 108,5mph

Most WWI planes would disintigrate way before reaching terminal velocity



Yes, Im sure that there were operational planes that were not as fast test indicated (then again there might be faster ones aswell). But that is same to all planes.

I don't feel like explaining True airspeed, so you can read about it yourself.
http://en.wikipedia.org/wiki/True_airspeed
"An aircraft flying at 15,000ft with an Indicated airspeed of 100kt, is actually flying at 130kt True airspeed, or 130kt through the air." As altitude increases, indicated airspeed decreases, and true airspeed increases. All the different airspeeds confuse a hell of a lot of people.

If your prop has too flat of pitch, then it will limit your top speed, but simply having a prop with more pitch isn't going to help you a whole lot. Remember that multiplying drag factor comes back and bites you in the ass again. Having a prop with more pitch, designed for a higher airspeed is going to hurt your climb more than it is going to help your top speed on a draggy plane. Pretty much why the constant speed / variable pitch prop came about eventually.

Yes, I know WW1 planes are draggy, I was simply referencing the modern plane to show that it is possible to go fast on a small amount of power, and to show how much drag affected the WW1 planes. 200mph on 65hp compared to 100mph on 200hp.
The little plane I mention will have a prop with a very high pitch angle, it is designed for the high speed. The plane isn't going to accelerate or take off very quickly. However it will accelerate quickly in a dive, as there isn't much in the way of drag holding it back. But it will not accelerate under it's own power quickly, simply because the prop is not designed to be efficient at lower speeds.

My reference to flight numbers not always matching book numbers is simply pointing out that even if the flight model in ROF exactly matches numbers found in some book somewhere, it still might not be how it actually performed. You also have to remember that those were crude planes, mostly hand built and probably in hurry. I bet no two of them behaved exactly the same. Even modern planes of the same model all have their own personality.

Still a little drunk from the bar, so stuff might not be in a real sensible order up there.

I know what true/indicated airspeed is. I ment that true airspeed decreases as engine loses power at altitude.



Uh, yes. That probellor limits same way less draggy plane. Thats why I said engine/probellor was more important (as most engines were direct drive engine RPM was important aswell what pitch were best).



Yes, I know. My point was that all them were draggy and drag difference between late WWI planes was not that huge. IE extra drag that Dr.I got with third wing was compensated somewhat with absent of wing wires, etc.



Agreed, but it same in every other plane Neoqb models



It is ok, just please dont pyramid quote. It is hard to reply in order

Josef Carl Jacobs:

From early 1918 onwards, Jacobs started flying the Fokker Dr.I triplane with Jasta 7, and had his aircraft finished in a distinctive black scheme. The Dr I was his favorite mount until October 1918 and he used its maneuverability to his advantage, becoming the triplane's highest scoring ace, with over 30 confirmed victories.

So in the hands of a good pilot, she held her own in the air.

The reference to the 83 mph of the Dr.1 was what I read she would do when in service at the front lines at combat altitude. Antony Fokker was a salesman and over stated everything. At the flight trials the planes were clean when flown and not in combat configuration or have the wear-and-tear of the days and months at the front.

The Dr.1 is likely to become one of my German planes of choice, I suspect. I'm not a natural BnZ pilot, quite the opposite in fact - so given time and practice, I'm hoping I'll be able to really get the most out of the Dr.1.

I'm hoping so, at least. I don't think it's an especially handsome aircraft, looks/pop-culture wise it doesn't appeal... but its flight characteristics do.

About flight models, I'm pretty sure my own Cessna is modeled wrong. The actual performance no where matches the numbers from the Pilot Operating Handbook. The cruise speed is slower than stated, the climb speed is lower than stated, the take off roll is longer than stated, and the fuel burn is higher than stated.
It's got a fresh engine in it too, so no blaming a old worn out engine.

Ok is the pilot then

No I'm kidding it's a specimen reply to tempt you to blow your cork at the inhumanity

Very interesting BlueRaven, statistics can be slippery yes, your Cessna may not be the Cessna flown to get those figures. Ask them to let you fly that one for closure if you discover they've sold you some other plane "I want the one in the advert! Shrink-wrapped!". Imagine getting the protective oyster-shell off that one

Ming

More seriously.

I've seen footage of (scale-model) RC prop planes having lost one wing but still being roughly controllable, flying on-edge

Can this behaviour scale up so that real planes can lose a wing and still be (roughly) controllable, not to fall out of the sky immediately?

I wonder if smaller planes with only one wing have (proportionally) less drag than real-size planes with only one wing, so that allows them the soft landing. While the proportionally more draggy full-size plane would drop like a stone perhaps in the Gedanken

Ming

Will you accept the flight performance data from Nieuport Aircraft of World War One, by Ray Sanger (as also listed by Windsock)?



Now actual German speed measurements for the Fokker Dr.I, taken at Adlershof airfield during WWI:



Converted to miles per hour:
157 km/h = 97 mph at 2780 m (9,118 ft)
147 km/h = 91 mph at 3200 m (10,496 ft)
139 km/h = 86 mph at 4180 m (13,710 ft.)

Data comparisions can certainly lead to misinterpretations, especially when considering the often quoted performance figures listed for the Fokker Dr.I, as an example at 13,100 ft the triplane's airspeed being 103 mph.

According to the Adlershof test above, the Fokker Dr.I was flying at 86 mph at 13,710 ft. I doubt the triplane lost 17 mph in only 610 feet.

These differences call into question the performance that's often quoted for the Fokker Dr.I. Wartime pilots never reported the Fokker Dr.I as being anything but a slow aircraft, but then I doubt they were debating the matter over data on charts.

Profile Puplications Nieuport 17 (nro 49):

Speed:

6500ft 107mph
10000ft 101mph


Profile Puplication Fokker Dr.I (nro 55):

Speed 102,5mph at 13 130ft (official german figures).

Also acceptance trials of 141/17 of october 1917:
Speed 118mph (and climb way faster than official figures)

Also those same trials are quoted that you posted.

German Aircraft of WWI (page 101):

Speed 165km/h at 4000m (103mph at 13130ft)

Windsock data file special, Fokker Dr.I

Speed 115mph at sealevel, 102,5mph at 13125ft



All in all I think there are lot more sources stating that 115mph than lower (which btw was very probable in worn out front line plane). Also there were other planes like Sopwith triplanes that was actually faster (with similar engine) so it is very probable that Fokker could do 115mph.