Isssue : breaking wing

[ridbobkan]

Hello Razbam team, we may have an new issue since last update.

Flying straight around 400 knots, then moving stick fully to left or right: aircraft is rolling over (at this stage, this is normal :lol: ) but after a few seconds, AoA is increasing until too much Gs and wing breakage.

 

Fly-by-wire should avoid this situation and keep the noze onto the horizon.

 

:pilotfly:

Last icon is just because I love it. :music_whistling:

[GGTharos]

Is that based on the m2k FBW manual?

[ridbobkan]

Is that based on the m2k FBW manual?

 

What do you mean by "that"?

[GGTharos]

I mean your statement that the FBW should avoid it.

[ridbobkan]

I mean your statement that the FBW should avoid it.

 

Ok; that's true it is more a guess than a statement.

I believe the FBW is also meant to keep the bird in a safe zone.

 

What do "people who know" think about that?

[Andrei]

Ok; that's true it is more a guess than a statement.

I believe the FBW is also meant to keep the bird in a safe zone.

 

With constant high rate roll you are creating excessive yaw as well which overstesses aircraft.

Read #5 in this piece here, keeping in mind that Mirage is a delta.

 

I do not believe that FBW was so smart at that time to handle such cases.

[ridbobkan]

With constant high rate roll you are creating excessive yaw as well which overstesses aircraft.

Read #5 in this piece here, keeping in mind that Mirage is a delta.

 

I do not believe that FBW was so smart at that time to handle such cases.

 

 

My guess comes from manual saying the fbw prevents pilots from being in over G situation. But maybe this is a specific situation.

[jojo]

Hello Razbam team, we may have an new issue since last update.

Flying straight around 400 knots, then moving stick fully to left or right: aircraft is rolling over (at this stage, this is normal :lol: ) but after a few seconds, AoA is increasing until too much Gs and wing breakage.

 

Fly-by-wire should avoid this situation and keep the noze onto the horizon.

 

:pilotfly:

Last icon is just because I love it. :music_whistling:

 

How many consecutives rolls are you performing ?

[IvanK]

With constant high rate roll you are creating excessive yaw as well which overstesses aircraft.

Read #5 in this piece here, keeping in mind that Mirage is a delta.

 

I do not believe that FBW was so smart at that time to handle such cases.

 

I think you are referring to the phenomena know as "Roll Coupling" which is a real issue in many of the earlier fighters. The Mirage III had real issues with this with strict IAS v number of sequential rolls. I believe the MIR2K FBW system should prevent the onset of Roll coupling.

[jojo]

You should limit to 2 consecutives full rolls. But I don't know if the FBW enforce this limitation or not...

[Zeus67]

You should limit to 2 consecutives full rolls. But I don't know if the FBW enforce this limitation or not...

 

I doubt it is able to do that. The FBW cannot read minds, so that is probably a warning in the pilot's manual.

[GGTharos]

The reason I asked is because I've seen footage of other FBW equipped aircraft departing after multiple consecutive rolls.

[ridbobkan]

http://plays.tv/video/576f7d6c4a4cf1d32c/air-to-air-conf-stick-full-left-no-up-no-down-

[jojo]

http://plays.tv/video/576f7d6c4a4cf1d32c/air-to-air-conf-stick-full-left-no-up-no-down-

 

So the pilot is advised to limit itself to 2 rolls. Here it breaks at 4.5 rolls.

So I'm not sure it would happen in real, but it's not a real issue here. Just avoid to do it :D

[GGTharos]

Likewise I'm not certain that it should break the wing, but excesive yaw should result in departure. I don't think it's easy to simulate roll coupling + everything else easily though.

[Crash_Horror]

[Darkbrotherhood7]

 

Nice vid!:thumbup:

[IvanK]

This Vid was in the early days of the FA18 specifically when the FCS software was being tweaked for the Blue Angles aeroplanes. This was Very early FCS software 5.3 Prom where the aeroplane could be a little squrily. In the A/B Hornet you got Yaw tone at 25sec Yaw rate as I recall. If you didn't honour the tone the next thing you saw was a rapid increase in AOA. Now increasing AOA and Yaw sets you up for the roll coupling entry. Later Software effectively makes this so much easier ... a case in point is the later model FA18 software loads allowing the "Pirouette" manoeuver seen at airshows.

[mvsgas]

I don't know if it is a FBW thing, but F-16 do not like excessive rolls either.

(excerpt)

PROHIBITED MANEUVERS

- Maximum command rolls exceeding 360 degrees of

bank angle change.

- Maximum command rolling maneuvers above 1.8

mach and either above 3g or below 35,000 feet MSL.

- Rudder rolls or rudder-assisted rolls of more than 90

degrees of bank angle change with any store on station 3, 4, 6, or 7.

- With LG and/or TEF’s down:

Maximum command rolls of more than 90 degrees of bank angle change.

- Abrupt roll reversals above 550 knots and below

20,000 feet MSL with the STORES CONFIG switch

in CAT I.

- Rapid rudder release or reversal above 300 knots/0.6

mach.

 

[jojo]

I don't know if it is a FBW thing, but F-16 do not like excessive rolls either.

(excerpt)

 

 

 

I think it's a thing with aircrafts which have a high roll rate (around 300deg/s)...