Flying round the airport to slow down the aircraft?

[Marijn]

only basic flight controls

You can always side-slip an aircraft to increase the drag further. For example, stick right and rudder left will cause the fuselage to be partly exposed to the incoming airstream and cause additional drag. This flight from a while ago shows the technique:

 

[N_Molson]

You can always side-slip an aircraft to increase the drag further.

Yes but I think airliners are quite sensitive to that, I remember a couple of fatal accidents caused by pilots hitting the rudder too agressively, causing the whole rudder to fail and rip apart in one case. That works on a small or military aircraft, but stresses the cell a lot. In the case of Flight 236, I think that emergency power isn't enough for fly-by-wire, so it could be very dangerous to do something like that.

 

[Marijn]

Yes but I think airliners are quite sensitive to that

It should not been done aggresively. You can control the angle quite precisely, so the amount of force can be controlled. I'll ask around how effective it is for airliners. It's an interesting question.

 

[Urwumpe]

Yes but I think airliners are quite sensitive to that, I remember a couple of fatal accidents caused by pilots hitting the rudder too agressively, causing the whole rudder to fail and rip apart in one case. That works on a small or military aircraft, but stresses the cell a lot. In the case of Flight 236, I think that emergency power isn't enough for fly-by-wire, so it could be very dangerous to do something like that.

In that case, it isn't about being rough on the rudder, but alternating left and right rudder pedal as if you are drummer in a speed metal band.

The dynamic loads then tire the composite structures of certain airliners and make then fail catastrophically. It is much less likely for properly designed metal aircraft (which take dynamic loads better) and even less likely for small aircraft with small rudders. A B-52H lost its rudder, because it was not designed strong enough for possible gust loads in 1964 - all B-52 had been improved since, the aircraft involved in the accident was repaired and continued service for 44 years.

 

[ChrisRowland]

Many years ago I was sitting in the back of an airliner on final approach, looking out of the window and realised that I could see the runway. The only way that could happen was because the pilot was side slipping. Not sure how much composite material was involved, it was a Viscount and the only composite available at that time was wood.

For litle aircraft side slipping is an accepted and very effective way to loose energy, as in the video from the back of a Ka21 that @Marijn posted. Like the landing prompts, keep it flying, keep it flying...

 

[N_Molson]

Well side winds can also cause the nose of the aircraft not being aligned with the runway during approach, then the tricky part is to still get all the wheels and the horizontal velocity vector inline right at the moment the aircraft hits the runway. That's something airline pilots do routinely.

I'd say side-slipping a bit is good for fine adjustments, but in the case of Flight 236, they were willingly way to high and fast (had too much energy), because when you're flying a big glider full of passengers aiming at a small island, not having enough energy is very likely to be catastrophic. That's a scenario where blowing the tires is much better than crashing on the sea shore, being (a bit) too fast was a safeguard in that case, because that "energy surplus" was everything they had in case of a wind turbulence or anything unexpected...

 

[Marijn]

side winds can also cause the nose of the aircraft not being aligned with the runway

Correct. The angle to correct for any crosswind while aligning for the runway is established with a normal, coordinated turn without slipping. The angle of any side-slipping stacks on top of that. You can still move left and right and therefore align with the runway by just varying the bank angle while keeping the rudder in fixed position to a side.

There are two theories when it comes to decide to slip either left or right. One says choose the direction which minimizes the angle with the runway alignment. The other theory says that you should keep the wing low whichever one that happens to be while turning to final from base leg to prevend having to roll over, which offsets the loss of energy.

 

[N_Molson]

There are two theories when it comes to decide to slip either left or right.

I guess engine torque also plays a role for monoprops (that are very common in light aviation). I really have a hard time taking off with the P-51 Mustang on FSX, still often roll straight into the control tower because of that insane torque ?

 

[ChrisRowland]

Wondered about cross winds, IIRC the Viscount just joined the local flying club Cessnas in a slightly larger circuit so there couldn't have been much wind. They have an 8 knot XWind limit.

I've not heard much debate about the direction to slip in UK gliding instucting circles, other than that a slipping turn, where you rudder out of the turn, gives higher sideslip angles and so even more drag. All this is either to correct for a vastly too high circuit into a field or an instructor getting fed up with ending up down the other end of the field yet again.

Some gliders won't side slip. The Jantar 2 I had said "slide slip not recommended" in the flight manual. Of course I tried it and at even moderate slip angles you lost elevator authority.

Few of us get the opportunity to fly a P51 and experience that insane torque. For smaller aircraft, with a mere 180 hp, there's not much of a problem. Maybe the feedback through the seat of your pants helps, also opening the throttle slowly (5 seconds or more). Gyroscopic effects can be noticable.

 

[N_Molson]

Yeah and those warbirds were meant for being efficient as combat machines, not to be easy to fly. Heard amongst the very worst was the F4U "Corsair", because not only the engine was enormous and the prop so big the engine at to be quite high over the ground, but also because they had to operate from aircraft carriers. A lot of ensigns killed themselves on first takeoff.

 

[Marijn]

I've not heard much debate about the direction to slip

There isn't any (official) recommendation either in NL on this I am aware of. The practical exam requires a student to do a 'wisselslip', meaning being able to slip from one side to the other on final. There's no clear defined side to begin the slip with including adressing possible x-wind and with regards to the side of the circuit being flown.

Since it's a manouver you'll pull off last minute in case of emergency, Imo, keeping the low wing low and gradually applying reverse rudder while turning final is generally the best way to do it in most practical situations.

The Jantar 2 I had said "slide slip not recommended" in the flight manual. Of course I tried it and at even moderate slip angles you lost elevator authority.

Nice plane! And an insteresting observation. Losing pitch control = bad.