The bounces

[Gibbo]

Someone may have a answer on this one..

 

Local SI was left head scratching by my worst landing yet. On a glide appraoch at tooradin and encountered a repeating bounce on touch down.

 

Approached at 60kn in a j-170 with full flap and fairly steep glide path using side slip to reduce height. On touch down I flared and held off as per normal but encountered a 'three wheel bounce' that repeated itself three times before I hit the throttle and performed a go around. I was still holding off when the three wheel bounce occured and repeated itself. Cross wind of around 5-6kn from the left so not really a concern.

 

It felt like the jab was caught tranisting in and out of the ground plane effect. Could this occur at around 35-40kn.

 

Gibbo

 

Any suggestions as to the cause?

 

 

[Student Pilot]

Too quick, you should be touching down with just mains then lower nosewheel later.

 

 

[Chucky]

I did the same thing but had a few extra bounces. Turns out I still had a littlle bit of power on...not much but just enough to make the aircraft want to become airborne again.

 

 

[lazerin]

Yup, sounds like you were coming in a little hot. This can be exacerbated by using the sideslip because as you come out of the sideslip, you will tend to gain a little airspeed.

 

As stated above, you should land on the mains first, not all three at once.

 

You have to fly the aircraft and hold it off as long as possible in the flare, thus ending up with a nose up attitude and hopefully a stall perfectly as the main wheels touch down. When the main wheels touch, remember to hold the elevator where it is, DON'T push the nose down and DON'T pull back again. Keeping it where it is will naturally hold the nosewheel up and slow the aircraft down to a point where the nosewheel will touchdown on its own.

 

This way, you will touch down with the lowest possible speed and gain control by using aerodynamic forces. So, try holding it off even more to achieve that nose up attitude and bleed off some more airspeed. The fine touch comes with balancing holding off and maintaining altitude and not gaining altitude.

 

 

[Guest TOSGcentral]

I really suggest that you find an instructor competent enough to explain and demonstrate to you that you do not land an aircrafr (or very seldom) but put it into a configuration where it is able to land itself and may concincingly teach you how to do so.

 

 

[Student Pilot]

Full flap should'nt be a problem.

 

 

[Guest brentc]

I was watching that landing Gibbo

 

It was a gusty crosswind so I'm not surprised that you got bounced around a bit. I did a pretty decent bouncer today and that's not normal for me. Would say the flap may cause that as suggested plus a reduction in just a few knots could help a lot. If you are holding back significantly on the stick it should settle eventually.

 

When I first flew the 170 with Ryan I was approaching at 55 knots, so by the time I was touching down it was a lot less; might be your problem. I was talking to Eugene a while back and the 60 knots they have been teaching was for a bit of extra safety margin so when you are more competent this can come down a little.

 

 

[poteroo]

As other posters have said - mains on 1st, which usually means a greater effort on the hold-off when your flare brings you level to the strip.

 

The aim of the nose high touchdown is to utilise aerodynamic drag - and full flap will improve this effect. Always my preference.

 

You probably shouldn't try to lower the nosewheel in any conscious movement, because the aircraft pivots at the mainwheels, and so, is going to want to fall onto it's nosewheel in a mains 1st touchdown. Your aim should be to apply an increasing back pressure on the controls, as the mains touch, which counters the pivot over the wheels.

 

This keeps your aerodynamic drag maximised, so you don't need any immediate braking. This means that the nosewheel will finally fall when you run out of elevator command. By this method, you avoid the Jabby wanting to head off, usually left, at high speed into the scrub.

 

happy days,

 

 

[turboplanner]

There is no way students should be experimenting with lower than recommended landing speeds; too much chance of a gust/wind drop/attention diverted on something else, resulting in an unexpected stall.

 

The same Jab lands fine at 60 kts on the mains, nose wheel just off, and backpressure maintained. Too much nose up and the long wings pick up any offset breeze.

 

 

[BigPete]

Hey Kev,

 

try using more than 1st flap but not full flap (around 30 deg) on late final. Electric flaps let you set them where you want (of course). Works good for me (J160), I only use all of the flap for short strip landings (40 deg) (the extra 10 deg really does help you to get in).

 

regards

 

 

[Yenn]

Good job you were in a nosewheel plane. The third bounce in a taildragger is usually disaster time. Just keep that nose up and let it land itself, if you push it down and get the mains on too fast even with the nose up it will bounce, then it will stall and come down nose first, which is not a happy way to go.

 

 

[Gibbo]

I was watching that landing Gibbo It was a gusty crosswind so I'm not surprised that you got bounced around a bit. I did a pretty decent bouncer today and that's not normal for me.

It was my worst landing on record.. Have 300plus landings under my it belt but caught me out a bit.

 

The J-170's are very floaty compared to a j-160 which I have spent most of my time in. Having spoken to a couple of more experianced pilots in the last couple of days both have 'suggested' that the speed was the biggest factor. Need to try some slower 55kn approaches next week. Only have 9 hours in a 170 so the learning curve continues.

 

Gibbo

 

 

[Guest brentc]

Kev, what's going to stop you from getting 55 knots on final is the throttle. You'll need to pull the throttle right back to as slow as you get get it to achieve 55 knots. I've found that I can bring it in very steep at 55 knots which surprises me as you'd think it would get away from the target speed. The only problem with this steep approach is that quite a flare is required before landing.

 

Turboplanner - 60 knots is fine for landing, IF you are actually doing 60 knots. The problem is that it usually creeps up on you.

 

 

[Student Pilot]

Remember the airspeed is only indicated not actual. So with position error you can be indicating 55 knots but the actual speed is faster because of the higher angle of attack.

 

 

[Bidgee]

As per TOSG. I was having trouble "landing" for a while until my instructor had me set up the AC in the correct configuration and told me to keep flying it until it decided to land itself.

 

Scott

 

 

[Guest sypkens]

with full flap and fairly steep glide path using side slip to reduce height.

Hi

 

I only fly drifters and do not have much experience with that marvelous technology flaps but one thing I was told is to never side slip with flaps. I read somewhere that it can blanket your rudder out but can it potentially blanket out your tailplane as well?

 

I am also not sure if the side slip and flaps point is airplane specific?

 

regards,

 

jan

 

 

[turboplanner]

My point about 60 knots was that it has a safety margin:

 

(a) If the attention wanders or the skills are still in the learning phase, and inadvertently there's a little too much flare you can find yourself in a stall pointing nose down at the ground.

 

(b) If you're more astute and can maintain 55 kts exactly, then what happens if your 15 knot head wind suddenly drops away to 5 kts?

 

You can't see wind, and as much as it may blow the same way all year, one day it will change, and you have no reserve.

 

I used to be a regular smartar:censored: in a Cherokee, always dropping over the fence and spot landing on the front edge of the piano keys, coming to a stop just beyond them, until I read a story on wind shear and Langewiesche' "Stick and Rudder" where he talks about gradient winds, and started to have second thoughts, (but still touched down close to the fence).

 

Then I had two major windshears in succession, avoiding flattening out the mangroves by a fast acting instructor the first time, and getting on the throttle fast enough the second time, so these days I don't cut corners with safety margins, and have been getting the 170 down at 60 kts with minute throttle reduction and just enough flare to ensure a mains touch, then zero throttle and holding stick back to keep the front wheel off a long as possible.

 

A number of posters offered suggestions based on the 160 or other aircraft, but the J170 wing is quite different, with exceptional lift in the denser southern air, finding even slight breezes, and this and it's longer length make it hard to get used to.

 

 

[Student Pilot]

I am also not sure if the side slip and flaps point is airplane specific?

It is, depends on Aircraft.

 

 

[Gibbo]

As per Brents earlier comment,

 

If he gets the bounces then everyone's in trouble...

 

I would not call myself a completely inexperianced pilot having flown around the country 3 times in the past year but just on the longer side of the learning curve. 200 hours in less than eighteen months of flying.

 

Tooradin can be a "nasty" place at times with the gusts and crosswinds making each landing slightly interesting at times. I have seen a couple of very experianced pilots almost become unglued there.

 

 

 

 

 

Excessive speed (I believe) was the major contributing factor in this case but what I should have done is gone round before the 'third' bounce. (Human factors and decision making anyone!).

 

The COG was always near the rear (or behind) of the mains at all times. It felt like the jab was skipping 18 or so inches into the air and then running out of lift. No twisting or inclination to move the COG forward.

 

GG

 

 

[Guest brentc]

Often an instructor will tell you to keep the nose level with the horizon until the speed gets to the right approach speed when you turn onto base. Whilst this seems time consuming at the time it's almost guaranteed to get you down to the right speed for approach. Personally I often leave slowing down far too late and end up with a little side slip to reduce speed and lose height.

 

 

[Yenn]

I don't see he problem as too much speed, it is a case of putting it down with too much speed, which is not the same as landing it. You must hold it off until the speed is low enough to land it properly. I have landed after an approach at too high a speed. it only means you land further along the runway. If the first turnoff is a long way along the runway the options are to approach and land as normal, or approach too fast and just hold it off.

 

 

[Gibbo]

Often an instructor will tell you to keep the nose level with the horizon until the speed gets to the right approach speed when you turn onto base. .

I tend to perform appraoches in the following order on the end of downwind..

 

Carb Heat + Fuel pump

 

Thottle back to 1600-1800rpm

 

Start trimming for 70kn

 

Use the base turn to wash off excessive speed. (higher speed = reduced stall likelyhood)

 

Settle at approach speed

 

Flaps

 

re-trim

 

Final

 

The comments made about the differance between the 160 and 170 in the southern air are true. The aircraft types handle completely differantly in the colder air. I am still having trouble coming to terms with the increased glide ratio which caused the problem in the initial stages.. Few more hours and I should be used to it.

 

Gibbo

 

 

[tvaner]

Hi Gibbo,

 

I was at YTDN 3 or 4 weeks ago hanging over the fence (as you do) and saw the 165 (4587) doing T&G's with a solo pilot on RWY 22 & the aircraft was doing what you have described. When the mains touched, the nose was forced down then the mains again & so forth. After a couple of these the pilot chose to go round again. This happened a few times before a reasonable landing was achieved.

 

From what I saw the aircraft was not being held off sufficiently after flare. ie the nose was only approx. 6 -10" off the ground at touch down. It appeared the pilot was not increasing the back pressure during the hold-off enough at the critical time, which would have held the nose wheel clear of the runway during landing.

 

PS: I would suggest a couple of laps with the CFI to assist sorting this out. That's one of the reasons that he is there for. The 170 is a great aircraft, but not an easy one to handle on landing or when on the ground.

 

Hope observation this may help.

 

 

[Gibbo]

Keith,

 

Same aircraft but it wasn't me at that time. I have spoken to a couple of people who have had the same trouble with 4587. Going to have a bash this saturday afternoon with the new SI.

 

A couple of people made the comment last night that the other 170's dont tend to do it and they are suspect due to its history. Time will tell.

 

 

[Gibbo]

Hi Gibbo,From what I saw the aircraft was not being held off sufficiently after flare. ie the nose was only approx. 6 -10" off the ground at touch down. It appeared the pilot was not increasing the back pressure during the hold-off enough at the critical time, which would have held the nose wheel clear of the runway during landing.

Had the stick almost against the stopper and was holding it there. :confused:

 

Gibbo