M2000: control surfaces deflections

[Azrayen]

Hello Razbam team,

 

The screenshot below, that was posted today on Facebook by ED, made me notice what looks like an overrated deflection (beyond max possible value [edit] no scratch that, my mistake) for the Mirage's elevons:

(click to enlarge)

 

You'll find below the max deflection angles for control surfaces. Data from the flight manual.

Elevons (internal and external): +16°/-25°

Internal Slats: 17.5°

External Slats: 30°

Airbrakes (upperside): 55°

Airbrakes (underside): 68°

Rudder: +/- 25°

Nose Wheel Steering: +/- 46°

 

Would you please check this? :thumbup:

 

Thanks,

Az'

Edited September 19, 2015 by Azrayen
my mistake, sorry

[Joni]

there is a flight manual available??? WOW!

 

i read that razbam didnt have much to work on..............

[Cool Breeze]

Avialogs.com is a great resource for flight manual civilian and military. Many if not all are scanned originals.:book: :smartass: If you pay for a membership you can download the PDFs as well. Happy Flying!

 

http://www.avialogs.com

[Azrayen]

there is a flight manual available???

It's not meant to be, but it kind of id. Uncomplete, obsolete (not the RDI version but an older one) and in French.

May be useful anyway, as shown above.

[OnlyforDCS]

And you can measure this angle from the picture....how exactly?

[Lib]

Without measuring, every technician (like me) can easily see the angle is more than 16° :smilewink:

On that picture i would estimate 20-25°.

[OnlyforDCS]

Without measuring, every technician (like me) can easily see the angle is more than 16° :smilewink:

On that picture i would estimate 20-25°.

 

Which is within the limits (You have your + and - deflections mixed up).

[Lib]

I'm sur Azrayen pointed on the + limit, so no, +25° is out limits for the elevons.

Az' ? did i understood correctly your request ?

[VincentLaw]

I'm sur Azrayen pointed on the + limit, so no, +25° is out limits for the elevons.

In the attached picture the deflection is negative. Sign convention for elevons is negative for upward deflection and positive for downward deflection. It makes no sense to want more downward deflection anyway since both the pilot and airframe cannot withstand as many negative Gs.

[OnlyforDCS]

Then Azrayen has his limits mixed up. It doesnt make sense that the elevators can push the plane into negative G's more than into positive Gs.

 

Sniped by Vincent. Great minds think alike ;)

[Azrayen]

Uh... Indeed I didn't take into account the +/- convention. I'm not sure it was used at the time.

 

I guess I was enclined to think that the 25° value was the downwards deflection because of the number of parked Mirages I have been around: with no hyd pressure, the elevons drop under their own weight and I think they travel more than 16° then.

 

I also saw numerous Mirages displays, and can't remember the elevons going so far upwards (except, perhaps, for rolling the aircraft).

 

OTOH the "more positive than negative G" has merit too. What about the aircraft instability in that matter ?

 

I'll have to check, obviously. Sorry if I raised a false alarm. Will report ASAP.

Edited September 18, 2015 by Azrayen

[jojo]

Uh... Indeed I didn't take into account the +/- convention. I'm not sure it was used at the time.

 

I guess I was enclined to think that the 25° value was the downwards deflection because of the number of parked Mirages I have been around: with no hyd pressure, the elevons drop under their own weight and I think they travel more than 16° then.

 

I also saw numerous Mirages displays, and can't remember the elevons going so far upwards (except, perhaps, for rolling the aircraft).

 

OTOH the "more positive than negative G" has merit too. What about the aircraft instability in that matter ?

 

I'll have to check, obviously. Sorry if I raised a false alarm. Will report ASAP.

 

Hi Az'

 

I think they are good :thumbup:

[Azrayen]

OK thanks jojo. :thumbup:

 

My mistake then, the +/- convention is respected, and there is no "max deflection" problem.:doh:

 

And the following video shows that at low speed (or low air density I guess, i.e. higher altitude), the elevons do deflect a lot with a sole pitch order.

 

So I guess Razbam's implementation is correct, despite how surprised I was seeing this screenshot. And I just read that AFM is not implemented yet, perhaps this will have an influence too.

 

Anyway, sorry for the trouble. :blush: and keep up the good work with this dream aircraft :)

 

Regards,

Az'

Edited September 19, 2015 by Azrayen

[Lib]

In the attached picture the deflection is negative. Sign convention for elevons is negative for upward deflection and positive for downward deflection. It makes no sense to want more downward deflection anyway since both the pilot and airframe cannot withstand as many negative Gs.

 

 

:huh: i always thought positive deflection was when you pull the joystick (with the plane is right sens of course) and thought the limitations were mecanical stops, so + = elevons up - = elevons down.

 

But i doubt... what you say makes sens... But i wonder now if AZ' posted mecanical limitations or "piloting" limitations... because how to know for the manual author in witch sens will be the plane ?

 

EDIT : just found confirmation in a french manual : "positive steering will therefore generate a pricking movement of the aircraft" (google translate :smartass:). VincentLaw, you're right. :thumbup:

Edited September 19, 2015 by Lib