Nieuport 28

[+Geezer 3,569]

Had a pleasant morning starting the N28, a personal favorite of mine.  My recently obtained reference is full of detailed information that contradicts a lot of the stuff on the internet.  Two examples:

- The N28 was quickly retired because of PLANNING, not bad operational experience.  The N28 was ordered as a stopgap when it became clear the French aircraft industry could not deliver SPAD13s on schedule.  Turns out, several units resisted replacing their N28s with SPADs and continued flying them after SPADs were available.  Indeed, Billy Mitchell recommended continued production and use of the N28 as SPAD operational readiness was terrible, due to unreliable geared Hispano-Suiza engines.

- Today's widespread notion of shedding wing fabric is a distortion of the facts - shedding was a symptom, not the cause of the problem.  The cause was poorly understood dynamic stress causing structural failure - the leading edge sheared off the wing under high-G maneuvering, and pulled the fabric off the wing as it fell away.  A field mod, that partially fixed the problem,  was being implemented about the time the N28s were withdrawn from service.  Also, no pilot was ever killed by this partial wing failure.  In every case, the pilot was able to nurse the N28 down to a forced landing.

Edited November 12, 2017 by Geezer

[Heck 496]

If I remember correctly, the source I read stated that a seam of the upper wing fabric was located near the center of pressure on the upper wing surface during a high speed dive. This, combined with weak gluing caused the fabric to fail at that seam. By all accounts I've read, the 28 was an excellent fighter; fast, maneuverable, well armed, and, as you've stated, not considered a cast off by the men who flew it. The Spad 13 had operational issues all through its career, and according to Norman and Hall, pilots who flew that wanted a Spad built Spad, with a Hispano Suiza built Hisso, because the subcontractor work was problematic, and there were some subcontractors whose airframes, or engines, you did not want to fly. Those pilots who flew rotaries for the French, or the British, loved their maneuverability and reliability. The 28, like the Pfalz, was one of the most beautiful aircraft of WW1. I will love to see yours.

ps, What source did you read? I love reading about stuff like this.

Edited November 12, 2017 by Heck

[+Geezer 3,569]

1 hour ago, Heck said:

If I remember correctly, the source I read stated that a seam of the upper wing fabric was located near the center of pressure on the upper wing surface during a high speed dive. This, combined with weak gluing caused the fabric to fail at that seam.

ps, What source did you read? I love reading about stuff like this.

Yeah, I read the same stuff but this book is the definitive English language reference and conclusively proves the problem was misreported:  https://www.amazon.com/gp/product/0764329332/ref=od_aui_detailpages00?ie=UTF8&psc=1

The problem was not really understood until after the war because the primitive, low-velocity wind tunnels of the time did not accurately model varying aerodynamic pressures on wings during high-G maneuvering.  This resulted in a design flaw: the leading edge section, forward of the main spar, could not withstand high-G bending moments and broke off, dragging the wing fabric aft as the section fell away.  The fabric did not detach from the wing until AFTER the wing structure had failed.

This was misunderstood in some reports but not in others.  For some reason, the inaccurate reports survived while the accurate reports were buried in archives until discovered by the book's author.  For example, most photos of this problem were taken from behind the aircraft so they only showed the torn fabric, not the missing wing section.  Two ACCURATE photos, showing the missing leading edge section, are below.

Also shown is a fragment of the high quality artwork contained in the book.

[Stratos 3,192]

Thanks for explaining this forgotten part of WW1 aviation.

[Heck 496]

Cool information. Thank you, Geezer. I think I just found the Christmas present idea my wife has been bugging me about. Very interesting stuff.

[jeanba 1,920]

19 hours ago, Heck said:

 The Spad 13 had operational issues all through its career, and according to Norman and Hall, pilots who flew that wanted a Spad built Spad, with a Hispano Suiza built Hisso, because the subcontractor work was problematic, and there were some subcontractors whose airframes, or engines, you did not want to fly. Those pilots who flew rotaries for the French, or the British, loved their maneuverability and reliability. The 28, like the Pfalz, was one of the most beautiful aircraft of WW1. I will love to see yours.

ps, What source did you read? I love reading about stuff like this.

The Spad 13 235 hp was good and reliable in the french forces.

The spad 13 220 hp was not very reliable, and the Spad 13 200 hp was absolutly unreliable unless maintained by a skilled mecanician.

It seems that the problems were vibrations generated by the engine which damaged or broke the cooling system (as reported by meeting minutes beetween the aircraft maker and the French forces representatives)

But archives are a little sketchy

Note that most french aces were either highly skilled mecanicians (such as Fonck) or worked with very good mecanicians (Guynemer ...).

This was often key to their success, but particularly with the Spad 13

Lot of French pilots kept their trusty Spad 7 180 cv until July 1918, such as for instance Pelissier (an ace with 8-12 kills, officially 8)

Edited November 13, 2017 by jeanba

[+Geezer 3,569]

7 minutes ago, jeanba said:

But archives are a little sketchy

Yes, we should be cautious when drawing conclusions from incomplete data. 

The N28 book says American mechanics had trouble with brittle SPAD fuel lines that fractured with vibration, and the troublesome reduction gears of the 200 hp Hisso.  This resulted in American squadrons having lower operational readiness with SPADs than with N28s, whose 160hp Gnome appeared to be extremely reliable.  This could be attributable to the inexperience of American mechanics, most of whom had been in the military for only a year, sometimes less. 

Interestingly, the 300hp Hisso - that powered the Nieuport29 - was extremely reliable because it dispensed with the unreliable reduction gears.

[jeanba 1,920]

 

The main interest of rotary engine was their reliability and ease of maintenance.

[+Geezer 3,569]

tres elegant...

[+VonS 1,424]

5 hours ago, jeanba said:

The Spad 13 235 hp was good and reliable in the french forces.

The spad 13 220 hp was not very reliable, and the Spad 13 200 hp was absolutly unreliable unless maintained by a skilled mecanician.

It seems that the problems were vibrations generated by the engine which damaged or broke the cooling system (as reported by meeting minutes beetween the aircraft maker and the French forces representatives)

But archives are a little sketchy

Note that most french aces were either highly skilled mecanicians (such as Fonck) or worked with very good mecanicians (Guynemer ...).

This was often key to their success, but particularly with the Spad 13

Lot of French pilots kept their trusty Spad 7 180 cv until July 1918, such as for instance Pelissier (an ace with 8-12 kills, officially 8)

It would be lovely if random engine failure could be modelled on some of the geared engines such as the lower-hp Hissos, also for earlier variants of the SE5a (should models for an SE5 pop up eventually in FE2).

Have studied the engine section of the data inis very carefully over the last couple of days, experimenting with manifold pressure values, also oil pressure numbers, etc., including introduction of WEP values and separate delta number lists for WEP power values (as on many of the WW2 data inis available for StrikeFighters2) - and there are no changes. It's likely that FE2 does not recognize WEP entry calls (I realize that WEP was not available in WW1 but wanted to try "behind the scenes tricks" to see if this would give random engine damage...so far no results but will keep trying with other things...although I am very happy with the current state of things in FE2 when it's modded up).

Also have tried negative numbers under the BaseWindSection of the environsys.ini file, to test for evidence of turbulence (so far not possible...only implemented are horizontal winds...although there is some vertical "rumble"/buffeting in aircraft when they are close to stalling). Also tested arbitrary entries such as "BaseVerticalWindSection" and "BaseTurbulenceSection," but none of this "connects" with the game engine - I will try tweaking the "StallModel" entry in the aircraftobject.ini to see if more consistent buffeting can be exploited across aircraft types - this might help to create the illusion of turbulence in game.

Beautiful work on that Nieup. 28 Geezer! I see that we have a whole factory of WW1 types now up and running.

Happy flying,

Von S

Edited November 13, 2017 by VonS

[+VonS 1,424]

Was always bothered by some of the oddities of the Nieu. 28 data ini...even though I had tweaked it a couple of times already. Finally I realized where the problem was, today (drag values were too high for the wings in the unmodified sections of the data ini). Also corrected now are stall moment values (with the type dropping tail first, slightly, in a stall, as is correct for such a thin-winged fighter).

Most of the data from this post is still relevant:

https://combatace.com/forums/topic/90447-fm-numbers-4-fes-nieuport-28/?do=findComment&comment=731547

But it is now much improved in turns...bleeds energy slightly more slowly - tight turns are possible with the sensitive rudder now, but apply opposite aileron (and try not to drop much below about 100-110kph in tight turns). The type also does well in faster turns above about 150kph. If encountering a stall, put the nose down and use rudder to correct. The AI has also been slightly tweaked now to avoid tail "porpoising" because of the new stall moment values that make it slightly "tail heavy." Also, I recommend using about 30% throttle when landing, as with the SPADs - otherwise the type may stall and spin in. Throttle values are also now improved, giving smoother acceleration. (Will roll this into a ver. 9.1 update of the FM pack, but I'm posting it below, already.)

Happy flying,

Von S

Edit: Added the 24bis data ini file too with drag reduction values and proper stall moment characteristics (it had similar problems to the Nieu.28, with high drag values); now it stalls tail first as correct for thin-winged aircraft; also possible now are flat spins in it.

Edited November 17, 2018 by VonS
Data inis removed (included now with ver. 9.5 of the FM pack).

[+Geezer 3,569]

Lovely! 

I've often read of WW1 pilots having to crash land because their aux fuel tank had not been filled by their mechanics.  The N28 aux fuel tank wasn't usually filled because it was located on the right side of the pilot, guaranteeing a horrible death if it was hit by gunfire.  A really minor embellishment, but would add even more uncertainty to completion of a mission?