In-game Nieuport 28.C1 & Albatros D.Va sustained turn rate comparison to C++ simulations

[Holtzauge]

11 hours ago, US103_Rummell said:

Have you ever done any work on damage modelling? Asking for a friend

 

No, I have limited myself to flight models but my stance on the DM is pretty much aligned with the majority view expressed in this forum. I did a post yesterday here. But let's keep that issue separate from this thread please!

 

7 hours ago, TheSaxman said:

 

Nice to see some hard maths applied to show how wrong the Nieuport's flight modelling is. Now if only the devs would do something with it...

 

I want to emphasize that I think FC is a great simulator and in many aspects does a very good job of simulating the flight models of WW1 aircraft. However, that being said, there are of course in any flight simulator things that could be tweaked further, and like I said before, I think the first step would be for the developers to look at my simulation results in the book and see if we can find some common ground.

 

Edited October 22, 2022 by Holtzauge
Link wrong

[LufberyJAA]

This looks amazing, and I will surely buy a copy!

 

I've been lurking on this forum and on Discord for quite a while and flying single player because my cheap head-tracking solution was too cheap.

 

Anyway, I was so happy to see the N-28 in the game! I have devoured Theodor Hamady's book on the Nieuport 28, and this version "felt" like what I had read -- until I tried a dogfight, and then it didn't match the performance that contemporary pilots wrote about in their memoirs.

 

Thanks for your post!

[TheSaxman]

11 hours ago, LufberyJAA said:

This looks amazing, and I will surely buy a copy!

 

I've been lurking on this forum and on Discord for quite a while and flying single player because my cheap head-tracking solution was too cheap.

 

Anyway, I was so happy to see the N-28 in the game! I have devoured Theodor Hamady's book on the Nieuport 28, and this version "felt" like what I had read -- until I tried a dogfight, and then it didn't match the performance that contemporary pilots wrote about in their memoirs.

 

Thanks for your post!

I've found the maneuverability to be pretty good when nose-down (Split-S, Low Yo-Yo, etc.) or if you start your maneuvers with a ton of airspeed. The problem is as soon as you bleed off some E (and she bleeds E FAST unless the nose is down) or the nose pops above the horizon you almost completely lose elevator authority. I've looked up the history of the game's Nieuport going back to Rise of Flight, and it sounds like the prevailing theory is that the COG is placed too far forward and it's throwing off the rest of the flight model. In my testing, full stall sets in at around 80 on the dial. I THINK stall speed on the type is supposed to be 60km/h, which means the stall speed is also too high (this could also be an artifact of the COG).

[Holtzauge]

3 hours ago, TheSaxman said:

I've found the maneuverability to be pretty good when nose-down (Split-S, Low Yo-Yo, etc.) or if you start your maneuvers with a ton of airspeed. The problem is as soon as you bleed off some E (and she bleeds E FAST unless the nose is down) or the nose pops above the horizon you almost completely lose elevator authority. I've looked up the history of the game's Nieuport going back to Rise of Flight, and it sounds like the prevailing theory is that the COG is placed too far forward and it's throwing off the rest of the flight model. In my testing, full stall sets in at around 80 on the dial. I THINK stall speed on the type is supposed to be 60km/h, which means the stall speed is also too high (this could also be an artifact of the COG).

 

When it comes to retaining energy in high-g manouvers, my simulations indicate that the Nieuport N28 does pretty well here as well: The way I compare this in the book is to give all scouts the same starting conditions: Which is to from a certain altitude maintain a certain speed and g-load target. Since this (the g-load) is higher than what can be sustained while holding the speed and altitude constant, all planes descend in a spiral dive. The planes are then ranked based on the altitude they have left when the first one reaches ground level. Here again the N28 is one of the better planes which indicates good e-retention. Just how good it is and where it ranks will revealed in the book! 

 

PS: COG has a very minor impact on e-retention since extra trim drag due to sub-optimal CG location is minute compared to the main source of drag which is the induced drag from the wings.

[HagarTheHorrible]

4 hours ago, TheSaxman said:

I've found the maneuverability to be pretty good when nose-down (Split-S, Low Yo-Yo, etc.) or if you start your maneuvers with a ton of airspeed. The problem is as soon as you bleed off some E (and she bleeds E FAST unless the nose is down) or the nose pops above the horizon you almost completely lose elevator authority. I've looked up the history of the game's Nieuport going back to Rise of Flight, and it sounds like the prevailing theory is that the COG is placed too far forward and it's throwing off the rest of the flight model. In my testing, full stall sets in at around 80 on the dial. I THINK stall speed on the type is supposed to be 60km/h, which means the stall speed is also too high (this could also be an artifact of the COG).

If memory serves, when the 28 came out, in RoF, it was  noticeably tail heavy compared to the other aircraft.  Raising the tail, on the take off run took appreciably longer. 
 

 

Holtzauge,  Mr Sopwith had a notion of concentrating ‘elements’ as close to CoG as practicably possible, such as in the Camel and Dolphin.  Do your calculations notice any discernible impact with this design methodology and is it mentioned in the book ?

Edited October 24, 2022 by HagarTheHorrible

[TheSaxman]

59 minutes ago, Holtzauge said:

 

When it comes to retaining energy in high-g manouvers, my simulations indicate that the Nieuport N28 does pretty well here as well: The way I compare this in the book is to give all scouts the same starting conditions: Which is to from a certain altitude maintain a certain speed and g-load target. Since this (the g-load) is higher than what can be sustained while holding the speed and altitude constant, all planes descend in a spiral dive. The planes are then ranked based on the altitude they have left when the first one reaches ground level. Here again the N28 is one of the better planes which indicates good e-retention. Just how good it is and where it ranks will revealed in the book! 

 

PS: COG has a very minor impact on e-retention since extra trim drag due to sub-optimal CG location is minute compared to the main source of drag which is the induced drag from the wings.

 

I think we're again seeing a difference between the hard numbers and what's actually in the game. I watched the airspeed indicator, and in any sort of nose-high maneuver the N.28 sheds speed EXTREMELY fast, even if you're starting at 220km/h or higher.

 

The past discussions I was looking at indicated that the COG was impairing elevator authority. Couldn't this also be affecting energy retention during nose-high maneuvering as a secondary effect? IE, because the aircraft isn't responding to the elevators and negatively impacting turn rate, it's increasing drag from the wings at any attitude other level to the horizon as a result (basically, wings are turned against the direction of travel longer than they should be)?

[Holtzauge]

13 minutes ago, TheSaxman said:

 

I think we're again seeing a difference between the hard numbers and what's actually in the game. I watched the airspeed indicator, and in any sort of nose-high maneuver the N.28 sheds speed EXTREMELY fast, even if you're starting at 220km/h or higher.

 

The past discussions I was looking at indicated that the COG was impairing elevator authority. Couldn't this also be affecting energy retention during nose-high maneuvering as a secondary effect? IE, because the aircraft isn't responding to the elevators and negatively impacting turn rate, it's increasing drag from the wings at any attitude other level to the horizon as a result (basically, wings are turned against the direction of travel longer than they should be)?

 

Control authority is one thing, but that would be more connected to the ability to "command" a certain angle of attack with the elevator but this is usually a low dynamic pressure issue, i.e. when you are at low speeds. For example, with a very forward CG it can be problematical when landing to get the nose up sufficiently due to both the flaps and the forward CG "pulling" the nose down. At high speeds there should be no problem at all to get the needed aoa with the elevator for basically all planes and any drag associated to this will "drown" in the enormous induced drag the wing produces. This however said with the caveat that the stick forces are not too large but that is another kettle of fish entirely! And while this has been modeled in the BOX WW2 modules for planes like the Me-109 both for elevator and ailerons, I don't think its very prevalent in the WW1 modules? IIRC then you can move the ailerons pretty well even at high speeds in the WW1 kites? IRL however it's a different story, and Mikael Carlson has told me that the Pfalz D.VIII ailerons feel like they are set in concrete at higher speeds.

[BMA_Hellbender]

15 hours ago, HagarTheHorrible said:

If memory serves, when the 28 came out, in RoF, it was  noticeably tail heavy compared to the other aircraft.  Raising the tail, on the take off run took appreciably longer. 

 

14 hours ago, TheSaxman said:

The past discussions I was looking at indicated that the COG was impairing elevator authority. Couldn't this also be affecting energy retention during nose-high maneuvering as a secondary effect? IE, because the aircraft isn't responding to the elevators and negatively impacting turn rate, it's increasing drag from the wings at any attitude other level to the horizon as a result (basically, wings are turned against the direction of travel longer than they should be)?

 

The N28 was one of the original four RoF aircraft release in 2009, along with the SPAD XIII, Albatros D.Va and Fokker D.VII. Of those four only the Fokker D.VII has had a substantial FM rework when its elevator authority and roll adverse yaw was corrected sometime in in 2010-2011. The N28 had a small fix applied during the infamous RoF 1.034 update after I and several other people complained for years that its tail didn't lift off fast enough and provided conclusive video evidence that it should behave differently.

 

https://riseofflight.com/forum/topic/44725-version-1034/page-1

 

Over the years I've gone into lengthy discussions with both @Han (lead tester/designer of RoF/FC) as well as with Stuart Goldspink, who flew a restored Nieuport 28 at Old Warden and Stow Maries.

 

 

 

Both seem to agree that it was a pretty tough machine to fly that only saw limited success due to operational issues in the war, but whereas the RoF/FC N28 is what it is (excellent aileron authority, poor elevator authority, bleeds energy during maneuvers), Stuart Goldspink told me the following during a QA with the WW1 Aviation Heritage Trust in 2021:

 

• Very hard to "turn/bank" that is: roll into a turn. It suffers from the same poor aileron authority as the earlier Nieuport series of aircraft. During airshows he would have to start banking and applying rudder about 5-10 seconds before reaching the desired point or he would simply overshoot the audience. It's definitely a plane that wants to fly forward or upward. Once rolled into the turn it didn't have any problem performing the actual maneuver of moving along the lift vector in said bank, it was getting there in the first place that was hard. Basically the complete opposite of what we have in RoF/FC.
   
• Far more responsive than the Albatros D.Va, but not as responsive as the Sopwith Camel. Basically something in between a SPAD VII and a Nieuport 17/23, which is incidentally the planes it shares its DNA with.
   
• Not as pleasant to fly as the Albatros D.Va, more of a handful as all rotaries are, but a fun, wild ride.

 

 

Anyway, I've already spent far too much time and effort on researching the N28 and trying to get the devs to do something about it, who maintain that it's fine as-is. It's great that we have it in the first place. For an aircraft that has been so significant in US Air Force history you'd expect to see it in a few more flightsims. In WOFF it flies fine, for the record, but the FM is not nearly as complex there.

 

From a historical and technical perspective it also represents one of the three solutions to increasing rotary engine power over 120/130/150hp engines:

 

• Increase engine size to the physical limits of a rotary engine block: 230hp Bentley BR2 weighing 220kg (Sopwith Snipe)
   
• Increase engine complexity/efficiency with counter-rotating propeller: 160hp Siemens-Halske Sh.III weighing 195kg (Siemens-Schuckert D.III)
   
• Decrease weight and complexity by using a single valve: 160hp Gnome 9N Monosoupape weighing 154kg (Nieuport 28, also used on late Sopwith Camel)

Edited October 25, 2022 by =IRFC=Hellbender

[Trooper117]

I posted that video years ago on the RoF forums... I was making a point that there was no way you could have a take off roll like that with the N-28 in the game.

Notice how quickly the tail came up?... you couldn't achieve that kind of take off in RoF. I'm not sure if it has been improved since, it's been a good while since I've flown it. 

[BMA_Hellbender]

1 hour ago, Trooper117 said:

I posted that video years ago on the RoF forums... I was making a point that there was no way you could have a take off roll like that with the N-28 in the game.

Notice how quickly the tail came up?... you couldn't achieve that kind of take off in RoF. I'm not sure if it has been improved since, it's been a good while since I've flown it. 

 
The tail lifting off too slowly was corrected in RoF 1.034, nothing else. I had a discussion with @Han a few years prior who confirmed they would fix it eventually, but only this as he deemed that the rest of the FM is accurate.

 

Again I don’t mind them sticking to their guns as everything we had until then was reports from pilots, now with @Holtzauge’s calculations and book we may have some more conclusive evidence.

[Guest deleted@83466]

Thank you for that very thorough analysis, Hellbender. 

[Holtzauge]

On 10/24/2022 at 8:31 PM, HagarTheHorrible said:

Holtzauge,  Mr Sopwith had a notion of concentrating ‘elements’ as close to CoG as practicably possible, such as in the Camel and Dolphin.  Do your calculations notice any discernible impact with this design methodology and is it mentioned in the book ?

 

Concentrating things in the plane close to the CG means that the moment of inertia goes down. However, the weight of course stays the same. This will not affect any of the base performance numbers like speed, climb or turn rate. These are determined by the weight and the CG, not the moment of inertia.

 

However, the moment of inertia is not unimportant: It affects the agility of the plane so a plane with less moment of inertia will be perceived as being more lively and responsive. This goes for all axis, but it is usually most easy to perceive in roll: A good example is the P-38 Lightning which with augmented ailerons is capable of very high roll rates even at high speeds but the roll acceleration is poor due to two engines sitting out on the wing causing a lot of inertia. So following an adversary making rapid changes in roll is difficult even if the top roll rate is high. Same goes for the wing cannon pods on the Me-109 and Fw-190 MGFF: They hamper roll acceleration.

 

Maybe the agility was Sopwith’s motivation for concentering payload, or maybe it was simply to keep down the overall dimensions of the plane, thereby reducing drag and weight? Anyone has some quote from Sopwith that could shed some light on this?

 

The book only mentions handling in passing related to how it could impact the theoretical performance in the sense that things like bad stall and spin characteristics could affect say turn performance in that a pilot may hesitate to take his plane to the edge for this reason etc. However, I have included details about the handling of the Fokker Dr.1 based on interviews with Mikael Carlson, and the Sopwith Camel based on a previously unpublished essay by the late Javier Arango.

[ST_Catchov]

22 hours ago, SeaSerpent said:

Thank you for that very thorough analysis, Hellbender. 

 

Whoa what's happened to you man? Ease off the benzos and ditch the cigarette. Not cool.

[Guest deleted@83466]

What?

 

 

Edited October 26, 2022 by SeaSerpent
Haha, you had me going there for a sec, joker.

[Zooropa_Fly]

He's Australian. 

[Guest deleted@83466]

I’ll play the bogan a good song in the tunes section, in that case.

[NO.20_Krispy_Duck]

I'll buy a copy of the book when it comes out, and I hope it can help guide the developers to some updates for the FM. Keep working with the WW1 aircraft, the early aircraft don't always get the study and attention that the WW2 aircraft get.

[Holtzauge]

1 hour ago, NO.20_Krispy_Duck said:

I'll buy a copy of the book when it comes out, and I hope it can help guide the developers to some updates for the FM. Keep working with the WW1 aircraft, the early aircraft don't always get the study and attention that the WW2 aircraft get.

 

Thanks! And yes I agree: WW1 aviation does not get the attention it deserves.

 

I was not actually planning to write the book (I was working on a WW2 aircraft performance book which is now on the backburner!) but I got truly intrigued with the aerodynamics of bi- and triplanes. In fact it’s really complicated, the interference the stacked wings have on each other, and how to take it into account. I write quite a lot about this in the book: How it started with Lanchester in England, further built on my Prandtl, Betz and Munk and how the realization came towards the end of the war about what we today call induced drag and the importance of high aspect ratio wings. Today we take it for granted but as I explain in the book, this was unknown territory at the time. In addition, the effects of Reynolds number on wing profile drag was another blank area at the time and was why the designers of the time persisted with thin airfoils and couldn’t understand that thick wing profiles had aerodynamic advantages as well, on top of the obvious advantage that they allowed cantilever wings.

 

Another interesting thing specific to WW1 scouts is the fabric and rib stripping on the upper wing like Rickenbakker experienced in the Nieuport 28, and which also happened on Gontermann’s and Pastor’s Fokker Dr.I’s before they crashed. I got some interesting historical information from Achim Engels on this and I use Xfoil simulations to show how it happened scientifically in the book.

 

All interesting stuff if I may say so myself!

[ST_Catchov]

Your book deserves consideration Holtzy although it may be too high brow for my feeble mind. I tend to zone out with mathematical logarithms and calculus and stuff. I hope it's got pictures. One can never have too many Se5a pics.

 

On 10/28/2022 at 4:35 AM, Holtzauge said:

WW1 aviation does not get the attention it deserves.

 

 

Not only that but pre-WW1 aviation. Truly a fascinating period. People not into it are weirdos or worse unlike the members of this community. Or it's a failure of the school curriculum. 

[Holtzauge]

3 hours ago, ST_Catchov said:

Your book deserves consideration Holtzy although it may be too high brow for my feeble mind. I tend to zone out with mathematical logarithms and calculus and stuff. I hope it's got pictures. One can never have too many Se5a pics.

 

Not only that but pre-WW1 aviation. Truly a fascinating period. People not into it are weirdos or worse unlike the members of this community. Or it's a failure of the school curriculum. 

 

Well Catchov, there are a few equations in it but never fear: All the valuable data is presented in charts making it easy to compare the planes. As I said before, I think you will be pleased with the S.E.5a data in the book and yes, there are even a number of S.E.5a pictures in it as well!

 

Regarding weirdos, aren’t we all? Spending the amount of time we do with this arcane hobby and the history related to it. However, having recently retired, I can now max this out and do whatever pleases me, and since I’m getting to old to chase girls I figure this comes in to a very solid second place. 

[LufberyJAA]

On 10/27/2022 at 2:35 PM, Holtzauge said:

Another interesting thing specific to WW1 scouts is the fabric and rib stripping on the upper wing like Rickenbakker experienced in the Nieuport 28, and which also happened on Gontermann’s and Pastor’s Fokker Dr.I’s before they crashed. I got some interesting historical information from Achim Engels on this and I use Xfoil simulations to show how it happened scientifically in the book.

 

 

Hamady's book on the Nieuport 28 goes into a fair amount of depth on why this happened and what the fix should have been. If you don't have a copy, it's well worth picking up.

 

It's also worth noting that there were only four (if I recall correctly) instances of the N-28 shedding its upper wing fabric, and of those, only one was fatal.

 

The other thing that I find interesting is the perspectives of pilots, from WWI to the present day. I wrote and article in Aviation History on rotary engines (The Truth About Rotaries (historynet.com)). I interviewed Andy King who had at that time flown three Gnome powered aircraft, and Fred Murrin, another noted builder of rotary-powered replicas.

 

To quote those gentlemen from my article:

Quote

According to Murrin and King, often-repeated tales about tricky aircraft handling due to the gyroscopic effects of rotating engines—that the spinning mass of the engine made for very quick turns to the right and slow turns to the left—are exaggerated. “When you hear the stories about rotary engines being hard to fly, the problem was with the inexperienced people flying them,” explained King. “When I made my first flight in a rotary-powered aircraft, I landed and then realized that I hadn’t noticed any gyroscopic effects. An experienced pilot automatically compensates for those things. Turns to the right might be a little quicker, but that is because the rotary engine tends to pull the nose down [in that direction], and you make a quicker descending turn than you make a climbing turn.”

 

Murrin agreed: “There are small gyroscopic effects but nothing close to the exaggerated tales often repeated in print and in documentaries. You adjust for them much the same way you would if you were flying in mildly gusty conditions. The torque reactions are most notable during takeoff and gliding in for landing when ‘blipping’ the engine.”

 

Other factors had a more pronounced effect on aircraft handling. King noted that all the early rotary-powered planes had a lot of adverse yaw (the tendency of the plane’s nose to point in the opposite direction of a bank when star ting a turn), and all were tail-heavy, leading to a certain amount of instability in their handling.

 

Similarly, but with a different emphasis on turns, Hamady quotes several pilots flying Nieuports -- including from Frank Tallman's collection.  Highlights from those notes:

 

• Center of gravity can be forward or aft depending on how much fuel is in the forward (main) fuel tank. As it empties, the CG moves aft.
• With an aft CG, there is a strong tendency to pitch up, but there is still a slight tendency to pitch up with a forward GC.
• Takeoff performance is "stunning" -- 150 yards to take off at 45 mph with climb at 60 mph. It requires a lot of right rudder.
• Right rudder is required during full-power climbs
• Cruise at power setting 3 gives 85-90 mph and power setting 4 gives 120. There is no elevator trim and ~5 pound of forward pressure is required.
• The elevator is effective throughout the speed range
• Ailerons become very heavy above 90 mph.
• Turns to the left are much faster than to the right <- this is different from what the pilots above told me, but perhaps I'm reading too much into the "much quicker" description.
• The Nieuport 28 could accelerate faster in straight in level flight than the Spad XIII
• The N-28 "had a well-deserved reputation for agility and handling." It performed chandelles and loops beautifully, but with offset rudder at the top to counteract torque. The power of the Gnome pulled the airplane up and over the top of a loop easily. Stalls were straightforward.
• "Rudder and elevator controls were well-balanced and very effective, but aileron response was not." One of the pilots, Jim Appleby said that "It was easy to get into an Immelmann, but lack of aileron efficiency made it difficult to get out."

Anyway, part of what I really like about this game is that it simulates to a certain degree everything I've read about flying these planes. 

[Holtzauge]

7 hours ago, LufberyJAA said:

 

Hamady's book on the Nieuport 28 goes into a fair amount of depth on why this happened and what the fix should have been. If you don't have a copy, it's well worth picking up.

 

It's also worth noting that there were only four (if I recall correctly) instances of the N-28 shedding its upper wing fabric, and of those, only one was fatal.

 

 

Thanks for the tip about Hamady’s book. I have not read that particular book but I have seen an image showing how the stripping occurred on the Nieuport N.28:

 

 

Is this from that book? In that case it certainly looks interesting, since it gives an insight into exactly how the stripping occurred on the N.28.

 

However, In my book I am not looking at the particular design aspects of individual aircraft design but more on the root cause from an aerodynamic perspective and why you get such high forces on the leading edge and why it always occurred on the mid part of the upper wing and nowhere else. In my book I also show examples of this (the stripping) occurring on other aircraft types than the N.28.

 

Regarding fixes, Mikael Carson showed me this on the N.28 wing he was restoring and the gussets added to alleviate the problem. In the book I also mention the fixes done to the Fokker Dr.I, where the problem of the early Dr.I crashes was a combination of poor workmanship and a too weak design which Idflieg mandated to be beefed up before giving the clearance for resumed production.

 

7 hours ago, LufberyJAA said:

 

 

The other thing that I find interesting is the perspectives of pilots, from WWI to the present day. I wrote and article in Aviation History on rotary engines (The Truth About Rotaries (historynet.com)). I interviewed Andy King who had at that time flown three Gnome powered aircraft, and Fred Murrin, another noted builder of rotary-powered replicas.

 

 

That was a very good article on rotaries so thanks for linking to it. It’s seldom one sees such a good summation of the pros and cons of this engine type, and never in the same article. In addition, good to see another source indicating that the gyroscopic forces are manageable with the right pilot input. This is exactly what I write in my book as well, based on input from Mikael Carlson and from an essay by Javier Arango.

 

7 hours ago, LufberyJAA said:

 

Similarly, but with a different emphasis on turns, Hamady quotes several pilots flying Nieuports -- including from Frank Tallman's collection.  Highlights from those notes:

 

• Center of gravity can be forward or aft depending on how much fuel is in the forward (main) fuel tank. As it empties, the CG moves aft.
• With an aft CG, there is a strong tendency to pitch up, but there is still a slight tendency to pitch up with a forward GC.
• Takeoff performance is "stunning" -- 150 yards to take off at 45 mph with climb at 60 mph. It requires a lot of right rudder.
• Right rudder is required during full-power climbs
• Cruise at power setting 3 gives 85-90 mph and power setting 4 gives 120. There is no elevator trim and ~5 pound of forward pressure is required.
• The elevator is effective throughout the speed range
• Ailerons become very heavy above 90 mph.
• Turns to the left are much faster than to the right <- this is different from what the pilots above told me, but perhaps I'm reading too much into the "much quicker" description.
• The Nieuport 28 could accelerate faster in straight in level flight than the Spad XIII
• The N-28 "had a well-deserved reputation for agility and handling." It performed chandelles and loops beautifully, but with offset rudder at the top to counteract torque. The power of the Gnome pulled the airplane up and over the top of a loop easily. Stalls were straightforward.
• "Rudder and elevator controls were well-balanced and very effective, but aileron response was not." One of the pilots, Jim Appleby said that "It was easy to get into an Immelmann, but lack of aileron efficiency made it difficult to get out."

 

Interesting compilation. Thanks for posting. Next time I get hold of Mikael Carlson, I plan to ask him his thoughts about handling the Nieuport N.28 he recently restored. If and when I get that info I will of course post it in this forum.

 

BTW: The stiff ailerons and high control forces in roll seems to be a problem that afflicts most WW1 aircraft barring the Fokker’s with the elephant ear aerodynamic balancing.

 

[HagarTheHorrible]

“and from an essay by Javier Arango”

 

Will the book have a dedication to Mr Arango and does Mikael Carlson’s N 28 have inspection windows in the rear fuselage for the turnbuckles ?

[Holtzauge]

2 hours ago, HagarTheHorrible said:

“and from an essay by Javier Arango”

 

Will the book have a dedication to Mr Arango and does Mikael Carlson’s N 28 have inspection windows in the rear fuselage for the turnbuckles ?

 

Yes, I'm indebted to Javier Arango's estate for letting me quote and use information from the essay and I mention this in the book.

 

Regarding the turnbuckles, it was more than 2 years ago I spoke to Mikael about this and IIRC then he said that the turnbuckles on Mr. Arango's N.28 were not secured by a wire lock which is common practice and that they were placed in an un-inspectable part of the fuselage where there should have been no turnbuckles in the first place. Most likely no-one ever knew they were there before the accident.  However, I may be misremembering what Mikael said about this, and it may be so that the original WW1 Nieuports were outfitted like this but I seriously doubt it: Any designer (then and now) worth his salt would not place a flight critical component where it could not be inspected. But I'm willing to be proven wrong if someone can come up with a contemporary drawing showing such a setup. So that being said I doubt there is an inspection hatch because with a proper design it would not be needed in this case.

 

Edited October 31, 2022 by Holtzauge

[TheSaxman]

14 hours ago, LufberyJAA said:

It's also worth noting that there were only four (if I recall correctly) instances of the N-28 shedding its upper wing fabric, and of those, only one was fatal.

 

I find this particularly interesting, as many discussions I've seen on the Nieuport have exaggerated this to the point that it was assumed to be a chronic failure in the type. Yet if there are only four documented cases of it occurring, out of 300 aircraft built that's barely more than 1% of all aircraft produced, and one that could almost certainly be chalked up to individual variances in manufacture or materials quality.

[LufberyJAA]

11 hours ago, Holtzauge said:

 

Thanks for the tip about Hamady’s book. I have not read that particular book but I have seen an image showing how the stripping occurred on the Nieuport N.28:

 

 

Is this from that book? In that case it certainly looks interesting, since it gives an insight into exactly how the stripping occurred on the N.28.

 

 

Yup! That's from the appendix on wing failures in Hamady's book. It's very interesting.

[HagarTheHorrible]

36 minutes ago, LufberyJAA said:

Yup! That's from the appendix on wing failures in Hamady's book. It's very interesting.

Given the current wing DM, that spar cross section detail looks ‘interesting.  Is it a ‘typical’ Nieuport method ?  Is the central fillet made from ply ?  I’d always assumed that the spars, with the exception of cantilever spars, and possibly some of the larger bombers, were made from the solid.

[Chill31]

@LufberyJAA

@Holtzauge

 

"The other thing that I find interesting is the perspectives of pilots, from WWI to the present day. I wrote and article in Aviation History on rotary engines (The Truth About Rotaries (historynet.com)). I interviewed Andy King who had at that time flown three Gnome powered aircraft, and Fred Murrin, another noted builder of rotary-powered replicas."

 

Of note, Javier Arango, Fred Murrin, and Andrew King have never done aerobatics with rotary powered aircraft. 

 

They are accurate about the minor gyroscopic effect IF you are flying in a calm manner.  Aerobatics, specifically high acceleration maneuvers in any axis, cause the gyroscopic effects to become very pronounced.  To leave it at "rotary engines are really no different from any other engine" would be misleading for posterity.

Edited November 3, 2022 by Chill31

[J2_Trupobaw]

@Chill31  "IF you are flying in the calm manner." I always thought that biggest part of problem with rotaries were pilots whose experience was measured in weeks and tens of hours, not decades like people testing them today.

 

Are there techniques for an experienced pilot to say how noob-friendly the machine is?

Edited November 2, 2022 by J2_Trupobaw

[HagarTheHorrible]

7 hours ago, Chill31 said:

@LufberyJAA

@Holtzauge

 

"The other thing that I find interesting is the perspectives of pilots, from WWI to the present day. I wrote and article in Aviation History on rotary engines (The Truth About Rotaries (historynet.com)). I interviewed Andy King who had at that time flown three Gnome powered aircraft, and Fred Murrin, another noted builder of rotary-powered replicas."

 

Of note, Javier Arango, Fred Murrin, and Andrew King have every done aerobatics with rotary powered aircraft. 

 

They are accurate about the minor gyroscopic effect IF you are flying in a calm manner.  Aerobatics, specifically high acceleration maneuvers in any axis, cause the gyroscopic effects to become very pronounced.  To leave it at "rotary engines are really no different from any other engine" would be misleading for posterity.

That concurs with my thoughts (not that that ever counted for anything). Rotary’s having a square route type multiplying effect on manoeuvres, whether positive, or negative (help, or hindrance).  I can well imagine, that for ‘inexperienced’ pilots, in an era when the ‘art’ of pilotage was not well understood, it could get very frightening, very quickly, for the nervous, the ham fisted, the stressed or the panicked.  With knowledge and experience, I’m sure the quirks of rotaries could be used to  advantage, or the negatives minimised, but for many, riding, or even going close to, the edge, was probably a frightening experience, possibly with a razor sharp edge between success and failure, with little understanding of exactly where that edge was, or how to recover, calmly and coolly, once that point had been passed.

[Holtzauge]

16 hours ago, Chill31 said:

@LufberyJAA

@Holtzauge

 

"The other thing that I find interesting is the perspectives of pilots, from WWI to the present day. I wrote and article in Aviation History on rotary engines (The Truth About Rotaries (historynet.com)). I interviewed Andy King who had at that time flown three Gnome powered aircraft, and Fred Murrin, another noted builder of rotary-powered replicas."

 

Of note, Javier Arango, Fred Murrin, and Andrew King have every done aerobatics with rotary powered aircraft. 

 

They are accurate about the minor gyroscopic effect IF you are flying in a calm manner.  Aerobatics, specifically high acceleration maneuvers in any axis, cause the gyroscopic effects to become very pronounced.  To leave it at "rotary engines are really no different from any other engine" would be misleading for posterity.

 

I see what you mean and I think this is a good point. My guess why both Mikael Carlson and Javier Arango emphasize that gyroscopic forces are quite manageable (if the pilot knows what he is doing!) is to temper historical accounts to the contrary and reputations that certain machines were killers.

 

Maybe Javier Arango did not fly much aerobatics, but Mikael Carlson certainly does, but that being said, I don’t think theory contradicts that a lot of control surface deflection is needed at really high pitch and/or yaw rates, especially at low speeds, so it would probably be a good idea to add this info to Mikael’s and Javier’s accounts.

 

Although I am already working with proof copies of the book, I can still add text and I think your input about gyroscopic forces in more “aggressive” manovers would be good to have as well Chris, so I will send you a mail with some ideas about how this could be added.

 

8 hours ago, J2_Trupobaw said:

@Chill31  "IF you are flying in the calm manner." I always thought that biggest part of problem with rotaries were pilots whose experience was measured in weeks and tens of hours, not decades like people testing them today.

 

Are there techniques for an experienced pilot to say how noob-friendly the machine is?

 

Peter Garrison & Javier Arango fitted recording equipment to his Sopwith Camel that recorded control surface deflections and Mr. Arango said when he saw the results that he was quite surprised: He did not know that he was actually doing the things he was doing and he said that for him it was instinctive due to the hours he had on the plane. Later on he talks about just that in connection to novice pilots: They simply did not get sufficient training to understand how to fly the planes, and this was why they crashed.

 

Edited November 2, 2022 by Holtzauge
Reason for edit: Fixing layout because this forum STILL INSISTS on auto-merging posts. This needs to be FIXED!!!!!!

[AEthelraedUnraed]

On 10/19/2022 at 11:35 AM, Holtzauge said:

I’m not planning to give 1C my source code for the same reason 1C won’t give access to theirs but I am willing to share results. In addition, they don’t need to see the source code: Proof of the simulator’s ability lies in the results it gives, just like when we do tests in-game. Find a historical number you think is good, test it against your model and compare. If those numbers line up well then you can be pretty sure that the others (I mean the ones calculated by your simulation) are as well because then it’s just a matter of physics: There is no magic involved: The aircraft performance will be determined by the weight, power, wing profile, wing area, span etc.

 

As to the possibility to get changes done in-game, 1C has done modifications of the flight models on a number of occasions when presented with evidence that they find compelling. From my end that begins with publishing my book and letting them have a look at it and taking it from there. 

While I can understand you don't want to share your source code, I would be very interested in the methodology, if you're willing to share at least that. Specifically, I have a couple of questions:

- Why C++? I understand the base of your code was developed in the early 2000s, when it was probably a solid choice. However, wouldn't it be more efficient (if indeed a lot of work) to port it to MATLAB, Python or any other language that is commonly used for simulations? That might even allow these simulations to be performed on the (much faster) GPU.

- I presume you use some kind of grid of sample points where you calculate things like vectorised air pressure/movement? Are these samplepoints uniformly distributed, or is there some randomisation/jitter?

- Do you model all sections apart (e.g. a single wing), or do you model the whole aircraft at once? Airflow from the propeller might have an effect on the airflow around the fuselage, and the airflow around the fuselage might affect the airflow around the tail, and so on.

- What numerical solver do you use? How do you ensure convergence?

 

Please do not take my questions as any form of criticism - it is not! I'm just interested in engineering and solving computational problems. My questions stem from curiosity rather than a lack of trust in your models.

 

On 10/20/2022 at 12:06 PM, Holtzauge said:

Not any more but I used to. 

One of my friends recently moved to Sweden to join Ericsson in the 5G business. Do you happen to know any PhDs from Eindhoven, the Netherlands who joined Ericsson about 1.5 years ago??

[Holtzauge]

2 hours ago, AEthelraedUnraed said:

While I can understand you don't want to share your source code, I would be very interested in the methodology, if you're willing to share at least that. Specifically, I have a couple of questions:

- Why C++? I understand the base of your code was developed in the early 2000s, when it was probably a solid choice. However, wouldn't it be more efficient (if indeed a lot of work) to port it to MATLAB, Python or any other language that is commonly used for simulations? That might even allow these simulations to be performed on the (much faster) GPU.

- I presume you use some kind of grid of sample points where you calculate things like vectorised air pressure/movement? Are these samplepoints uniformly distributed, or is there some randomisation/jitter?

- Do you model all sections apart (e.g. a single wing), or do you model the whole aircraft at once? Airflow from the propeller might have an effect on the airflow around the fuselage, and the airflow around the fuselage might affect the airflow around the tail, and so on.

- What numerical solver do you use? How do you ensure convergence?

 

Please do not take my questions as any form of criticism - it is not! I'm just interested in engineering and solving computational problems. My questions stem from curiosity rather than a lack of trust in your models.

 

Why C++? Well, because there are tons of free compilators out there and because I had some experience with it through my work. Regarding the simulation engine, if you look at the “About” page on my site you will see that it builds on a SAAB document from the 1970’s. But before someone criticizes that it builds on such an old paper, remember that physics is the same then as it is now and that the old adage “Garbage in garbage out” is still very much valid even in this day and age of CFD simulations. Going off on a tangent, CFD still can’t solve Navier-Stokes equations for detached flow with major turbulent components for a whole aircraft close to Clmax which is where you are at in the tight turns which I cover in the book.

 

At work I did use the Ericsson Research simulator called Redhawk which is built on JAVA. But to be honest, JAVA and I never hit it off so I will continue with my trusty C++ thank you very much! Jokes aside, my code uses the interval halving method to converge so it’s stone age technology but it works, and if it takes 1 ms or 3 s to converge I don’t really care. However, what does matter are the results, and so far the simulation output has tied in nicely with available historical data.

 

About how I do it: I simply set up the force equations to a sufficient degree of accuracy and then integrate the changes in speed and acceleration etc and walk myself stepwise forward in small increments. The secret is of course HOW to assess the forces and on that point my lips will remain sealed. ?

 

2 hours ago, AEthelraedUnraed said:

One of my friends recently moved to Sweden to join Ericsson in the 5G business. Do you happen to know any PhDs from Eindhoven, the Netherlands who joined Ericsson about 1.5 years ago??

 

I know tons of PhD’s! Ericsson in Kista is littered with them! But I’m like Howard in The Big Bang Theory TV-series, I’m only an engineer with a Masters……?

 

On a more serious note, if he works with 5G 3GPP standardization with the Ericsson Research SWEA project then I might.

 

 

 

Edited November 3, 2022 by Holtzauge

[Chill31]

On 11/2/2022 at 3:25 AM, J2_Trupobaw said:

@Chill31  "IF you are flying in the calm manner." I always thought that biggest part of problem with rotaries were pilots whose experience was measured in weeks and tens of hours, not decades like people testing them today.

 

Are there techniques for an experienced pilot to say how noob-friendly the machine is?

Empirically speaking, anyone can say.  Stable aircraft are inherently noob friendly. That is why you see so many of the early war aircraft built with significant dihedral and long fuselages.  Stable airplanes make poor fighters though.

 

I would boil it down to this: aircraft that require more control input and more frequent control inputs are more challenging to fly. 

 

Why? The more you have to move the controls, the more instinctively you need to be able to do it.  If you have to think, you get behind the airplane, and the consequences of doing so are usually expensive, if not painful.

 

Rotary engines under accelerated G forces add in another control input (rudder) that requires constant modulation dependent upon the use of a separate control axis.  

 

On 11/2/2022 at 3:37 AM, HagarTheHorrible said:

That concurs with my thoughts (not that that ever counted for anything). Rotary’s having a square route type multiplying effect on manoeuvres, whether positive, or negative (help, or hindrance).  I can well imagine, that for ‘inexperienced’ pilots, in an era when the ‘art’ of pilotage was not well understood, it could get very frightening, very quickly, for the nervous, the ham fisted, the stressed or the panicked.  With knowledge and experience, I’m sure the quirks of rotaries could be used to  advantage, or the negatives minimised, but for many, riding, or even going close to, the edge, was probably a frightening experience, possibly with a razor sharp edge between success and failure, with little understanding of exactly where that edge was, or how to recover, calmly and coolly, once that point had been passed.

No doubt!  WWI planes are very simple machines compared to what we have today, but they really were sending pilots to fly at the front with so little training that a successful taleoff and landing that didnt damage the plane was a real accomplishment. Add in dogfighting, and there was a very steep hill to climb for those guys.

 

20 hours ago, Holtzauge said:

 

I see what you mean and I think this is a good point. My guess why both Mikael Carlson and Javier Arango emphasize that gyroscopic forces are quite manageable (if the pilot knows what he is doing!) is to temper historical accounts to the contrary and reputations that certain machines were killers.

 

Maybe Javier Arango did not fly much aerobatics, but Mikael Carlson certainly does, but that being said, I don’t think theory contradicts that a lot of control surface deflection is needed at really high pitch and/or yaw rates, especially at low speeds, so it would probably be a good idea to add this info to Mikael’s and Javier’s accounts.

 

Although I am already working with proof copies of the book, I can still add text and I think your input about gyroscopic forces in more “aggressive” manovers would be good to have as well Chris, so I will send you a mail with some ideas about how this could be added.

 

 

Peter Garrison & Javier Arango fitted recording equipment to his Sopwith Camel that recorded control surface deflections and Mr. Arango said when he saw the results that he was quite surprised: He did not know that he was actually doing the things he was doing and he said that for him it was instinctive due to the hours he had on the plane. Later on he talks about just that in connection to novice pilots: They simply did not get sufficient training to understand how to fly the planes, and this was why they crashed.

 

I would definitely agree with that. Inexperience kills!  And was the predominant reason pilots crashed in WWI.  

 

I would be 2 or 3 times more confident in a pilot to go fly an SE5 or Alby in combat over any rotary powered fighter.  

 

I am excited for your book! Happy to help in any way you need.  

[Holtzauge]

1 hour ago, Chill31 said:

I am excited for your book! Happy to help in any way you need.  

 

Great! And thanks for that! I just sent you a text via mail aiming to capture your input regarding handling and gyroscopic forces, so I would appreciate if you proof read that and make any necessary additions and then I'll add that together with the other input from Javier Arango and Mikael Carlson.

 

 

Edited November 3, 2022 by Holtzauge

[HagarTheHorrible]

9 hours ago, Chill31 said:

I would boil it down to this: aircraft that require more control input and more frequent control inputs are more challenging to fly. 

 

Why? The more you have to move the controls, the more instinctively you need to be able to do it.  If you have to think, you get behind the airplane, and the consequences of doing so are usually expensive, if not painful.

That’s a rather complicated way to say “Clouds are NOT your friend, stay way from the clouds”, or at least, I think, that’s what the spirit, I conjured up with the ouija board last night, was saying, although, that said, it might have been something to do with soccer, spirit messages can be a bit confusing and indistinct at times, he just kept saying “a ball, a ball” or something to that affect.

[Chill31]

18 hours ago, HagarTheHorrible said:

That’s a rather complicated way to say “Clouds are NOT your friend, stay way from the clouds”, or at least, I think, that’s what the spirit, I conjured up with the ouija board last night, was saying, although, that said, it might have been something to do with soccer, spirit messages can be a bit confusing and indistinct at times, he just kept saying “a ball, a ball” or something to that affect.

Im not following you here...

[J2_Trupobaw]

On 11/3/2022 at 2:49 PM, Chill31 said:

Empirically speaking, anyone can say.  Stable aircraft are inherently noob friendly. That is why you see so many of the early war aircraft built with significant dihedral and long fuselages.  Stable airplanes make poor fighters though.

 

I would boil it down to this: aircraft that require more control input and more frequent control inputs are more challenging to fly. 

 

Why? The more you have to move the controls, the more instinctively you need to be able to do it.  If you have to think, you get behind the airplane, and the consequences of doing so are usually expensive, if not painful.

 

That's very interesting because our RoF/FC ALbatros D.Va is both very responsible to controls and very noob friendly; come to think of it it is both very stable and very maneuverable... Does it make it an impossible plane?

Edited November 4, 2022 by J2_Trupobaw

[HagarTheHorrible]

4 hours ago, Chill31 said:

Im not following you here...

That’s because I have a ‘unique’ and rubbish sense of humour.

 

The instability, and ‘constant’ control corrections, of some designs, allied to the sparse instrumentation, would have made flying in, or through, cloud, something of a challenge.  A Be2c, less so.  If you recall, Albert Ball ,was last seen exiting a cloud, at low level, and with something of an unfortunate attitude.  That said, it was in the ‘relatively’ stable Se5, rather than his N 17, hence my reference to “a ball, a ball”.

[LufberyJAA]

On 10/31/2022 at 5:12 AM, Holtzauge said:

 

Thanks for the tip about Hamady’s book. I have not read that particular book but I have seen an image showing how the stripping occurred on the Nieuport N.28:

 

 

Is this from that book? In that case it certainly looks interesting, since it gives an insight into exactly how the stripping occurred on the N.28.

 

 

Yup! That's from the appendix on wing failures in Hamady's book. It's very interesting.

Hi all,

 

I had a super busy week, and wasn't able to log on. I followed the discussion, however, and think this discussion has some really valuable information in it. 

 

Regarding good/experienced pilots automatically correcting and accommodating aircraft movement tendencies while flying to the point that they don't notice they're doing it — A. S. G. Lee in his book Open Cockpit (a follow-up to No Parachute) talks about attending an advanced flight school after the war ended. I don't have the book handy right now, so I can't get a direct quote, but the gist was that during the war, he knew how to fly, but during the advanced flight training, he realized just how little he really knew about flying.

 

Regards,

-Drew