Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
convair880mfan
Topic Author
Posts: 324
Joined: Fri Jun 25, 2021 12:33 am

What does slat extension do to the attitude of an aircraft on approach?

Thu Oct 28, 2021 7:49 pm

Does the nose balloon up and are trim changes necessary after slats are extended? Does it depend on the aircraft? Am mostly interested in the DC-10 and MD-11 but would value information on any aircraft?

Which leading/trailing edge flap or slat settings require the largest trim changes?

I mentioned in a previous post that lack of slats on the DC-9-15 seemed to give it a definite nose down attitude all the way to landing although slight pitch variations could be felt all the way down.

Thanks for any information.
 
GalaxyFlyer
Posts: 9180
Joined: Fri Jan 01, 2016 4:44 am

Re: What does slat extension do to the attitude of an aircraft on approach?

Thu Oct 28, 2021 7:58 pm

If you maintain the same speed, not very noticeable on the types I have flown and not much if you slow. Flaps create more trim change.
 
flipdewaf
Posts: 4488
Joined: Thu Jul 20, 2006 6:28 am

Re: What does slat extension do to the attitude of an aircraft on approach?

Thu Oct 28, 2021 8:11 pm

As galaxy said, it shouldn’t be much if anything. Although not strictly true it was always useful for me to think about slats altering your Clmax and flaps altering your zero lift line, the ballooning happening because you effectively just changed the AoA (by moving the zero point).

Fred


Sent from my iPad using Tapatalk
 
GalaxyFlyer
Posts: 9180
Joined: Fri Jan 01, 2016 4:44 am

Re: What does slat extension do to the attitude of an aircraft on approach?

Thu Oct 28, 2021 9:28 pm

The F-100 had Handley-Page slats that moved as a function of AoA. We’d fly around in close formation, dive bomb recovery, fighting wing and never even think about the slats. I’d guess if one side hung up, it would exciting. In 1G, they came out at about 290, you could see them moving while in formation. The pattern and initial was blown at 300, so they’d be in until maybe the echelon turn to initial and you’d see lead’s slats go in and out.
 
User avatar
Aaron747
Posts: 17836
Joined: Thu Aug 07, 2003 2:07 am

Re: What does slat extension do to the attitude of an aircraft on approach?

Thu Oct 28, 2021 10:36 pm

convair880mfan wrote:
Does the nose balloon up and are trim changes necessary after slats are extended? Does it depend on the aircraft? Am mostly interested in the DC-10 and MD-11 but would value information on any aircraft?

Which leading/trailing edge flap or slat settings require the largest trim changes?

I mentioned in a previous post that lack of slats on the DC-9-15 seemed to give it a definite nose down attitude all the way to landing although slight pitch variations could be felt all the way down.

Thanks for any information.


You mention the MD-11 a fair amount recently - why that aircraft?
 
GalaxyFlyer
Posts: 9180
Joined: Fri Jan 01, 2016 4:44 am

Re: What does slat extension do to the attitude of an aircraft on approach?

Fri Oct 29, 2021 12:14 am

Now, a slatted wing will produce a more nose up attitude on final—slats create a wider working range of AoA for the wing.
 
User avatar
Starlionblue
Posts: 21060
Joined: Fri Feb 27, 2004 9:54 pm

Re: What does slat extension do to the attitude of an aircraft on approach?

Fri Oct 29, 2021 12:32 am

The A330 has a noticeable pitch up when you extend the slats (and first step of flaps which is almost nothing). Call it from 4 to 8 degrees nose up to maintain level flight at around 220 knots. If you're hand-flying you need to put in some forward stick to avoid ballooning. Once the flaps come out, the pitch goes back to about 5 degrees.

There's a trim change, obviously, but automatic since it is an Airbus.
 
e38
Posts: 933
Joined: Sun May 04, 2008 10:09 pm

Re: What does slat extension do to the attitude of an aircraft on approach?

Fri Oct 29, 2021 1:23 am

convair880mfan wrote:
Which leading/trailing edge flap or slat settings require the largest trim changes?


convair880mfan, on the Airbus A320 series, the largest trim change requirement, in my opinion, occurs inflight when going from Flaps 1 to Flaps 2.

Inflight, when you select Flaps 1, the leading edge slats extend to 18 degrees while the flaps remain retracted. Then, when selecting Flaps 2, the leading edge slats further extend to 22 degrees and the flaps extend to 15 degrees. The autotrim system responds with forward (nose down) trim, which seems to be slightly more than when transitioning between other flap settings.

e38

Who is online

Users browsing this forum: No registered users and 17 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos