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5 minutes ago, RFguy said:

airspeed should be maintained that permits positive  aircraft control and authority.

 

I'd say on  a straight approach in little or nil wind, I dont think there is any issue with flying at 55 kts in  (45kts stall) instead of 65 kts

Airspeed should be maintained at the target (recommended) approach speed. Slowing down to lose height is OK, until it isn't.

 

Short field approaches are pretty much by definition riskier than normal approaches - otherwise you would always use the short field speed.

 

Some aircraft have significant inaccuracies in the airspeed indication at slow speeds, so you might not have the margin you think you have.

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Hi everyone, I recently had an opportunity to fly the Jabiru J230. I had the flaps fully extended, power off and speed about 70 knots on finals, with the trim set fully back. As a part of normal

@anjum_jabiru , 70 kts is a bit hot on finals with full flap isnt it ?  I would have thought more like 65, then 60 late late (nil wind, good condix)    BTW my J230 does not have a pronounced

J230D: my best approach starts with slowing the aircraft on late downwind abeam the threshold. Carby heat on and reduce rpm to 1600, trim back to maintain circuit ht. 84kt 1/2 flap. Turn base and fly

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1 hour ago, RFguy said:

Maybe I didnt explain myself-  I dont hold the nose  it up so its about to buffet and fall out of the sky

 

- airspeed should be maintained that permits positive  aircraft control and authority.

 

I'd say on  a straight approach in little or nil wind, I dont think there is any issue with flying at 55 kts in  (45kts stall) instead of 65 kts.  Just keep your eagle eye on  the airspeed  and fly the aircraft.... On a short field approach  you  may do something like that anyway IE maybe to  reduce air speed over the fence. 

 

sure you can lose height by pointing the aircraft down but in aircraft I fly you very quickly run into VFE as you pointed out.  and then that's speed that has to be removed.

 

For 45kts stall I will approach between 58.5 and 63 kts. (1.3 to 1.4 times stall). Depending on wind / weather conditions.

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In calm conditions I don't think you need to carry that margin in the latter part of the approach. It's safe of course but you will use a lot of runway. The wind and gust allowances relate well to other conditions and may exceed your 1.3 vs A powered approach will enable a tighter control of approach speed. It's quicker to react than just a pitch change. Regardless you should have stability in the later parts of the approach. You are more likely to make a good landing from a good approach.  Nev

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I used a sideslip on my PPL flight test during the forced landing initial phase, in order to position to the field I was gunning for. The examiner was impressed that I had that extra tool in the toolbox..

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Some of my thoughts if you are interested. I was trained to always trim the aircraft for your current stage off flight and configuration. This leads to accurate flying, especially if slightly distracted by a frequency change or traffic lookout. It’s often tempting to fly, with the trimmers....a No-no, my military flight instructor would make me run three times around dispersal for that! Rather, select the attitude, hold it, then trim pressures off the controls. Trimming to hold the speed (nose attitude) on final helps towards a good landing, fighting elevator pressure during the hold off, can be the difference between a greaser and an arrival I think. I confess on short final, I might trim even a little nose up. This does of course, lead to a large trim change on a go around.

However, you should anticipate this and trim systems are normally quite fast, so re-trimming for the go around should not be an issue, but yes, it is a busy time in the cockpit. In my Gazelle I trim almost full nose up on short final, on the go around, I need to move the lever forward to the take off position, otherwise with slipstream effect and holding the climb nose attitude, if I don’t trim, I need to hold a bit of forward pressure on the stick. The Gazelle is nice because it doesn’t suffer from the “you are going nowhere” when going around with full flap. The C172 on a hot day, can hardly climb with full flap.  A lot of aircraft complicate the go around further by making it vital, you raise that flap to a take off setting. Remember, up to around 14 degrees flap, you get a lot more lift compared to little drag. Beyond 14 degrees, the ratio reverses!

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Posted (edited)

I guess in discussing flaps, why do we want high drag with land flaps? The C172, for it’s size, has great Fowler flaps, but at 40 degrees, those are like two barn doors, no wonder the poor thing struggles to climb. Like Nev said in an earlier post above, aircraft speed response to power changes is faster, with high drag. Another consideration is older generation jet engines had a lot of throttle lag. They took a looong time to spool up from a low % RPM. This was a problem on final approach, if you were getting low on final....if you needed power. With high drag, you could fly the approach with a lot of power on, leading to much faster throttle response. This is true when flying a “jet approach”, controlling the glide slope with attitude, speed with power. Most of us will probably fly glide slope control with power, speed maintenance with attitude changes. On a go around, you need now to get rid of that drag. Aircraft sink when raising flaps, loss of lift. But this is not much with raising a land flap setting. I notice the sink and trim change more with raising take off flap, as that lower flap angle of around 14 degrees, effects lift more. Aerodynamics is fun!

 

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