A word of caution to Jab guys

[Guest Qwerty]

QUOTE FROM TURBOPLANNER IN ANOTHER THREAD

 

[Thanks Jabby, maybe a word of caution to Jab guys.

 

I'd come in on full flap with an instructor who told me to go up by myself just as I exited the runway. In the conversation I forgot to bring the flaps up, and because I was just doing a bit more than a touch and go, made the mistake of not stopping to to my full preflight checks.

 

As a result, I was unaware I was taking off with full flap (J170).

 

The first I knew, the nose rotated normally and the aircraft lifted off a few feet then sat there wallowing with no increase in speed.

 

Fortunately I realised what I'd done and shoved the nose down, and had to hold it down quite firmly, knowing if I dumped the flaps it would probably sink on to the runway near the end fence. The speed built up and I made a shallow climb out - and resolved never to make the same mistake again.]

 

I did basically the same thing in my jab but because it is insanely overpowered, it accelerated through an ever tightening upward arc. I needed to be reasonably forcefull to keep the nose down till I sorted out the whole mess. By the time I was flying sensibly I was 100' AGL and about 70 m from the power on point on the strip.

 

Any body else have a flap related occurence?? I'd like to know more and I'd like to know what other responses these things can provide. The results of taking off with full flap certainly gained my full attention.

 

Qwerty

 

 

[Yenn]

I did it in a C150 as student solo pilot years ago. Took me a whilr to work out what was wrong, kept pushing the nose down, but no speed increase. In the end I saw them in the corner of my eye. very embarassing.

 

 

[turboplanner]

Yes, Brent, perhaps you would be happier commenting on another thread.

 

I described an event which actually happened.

 

 

[Guest Qwerty]

What??????? Brentc, There is no advice here (yet).

 

I suddenly found myself looking skyward, with the a/c climbing and accelerating at ever steepening(?) attitude. I am sure that, left to its own devices, I was well on my my to being taken for an uncomanded (unintentional) loop at ground level. It frightened the bejesus out of me. I was interested to read Turbz experience in the 160/170? I'd like to hear what else the things can do to you if you take your eye off them for more than a nanosecond. Remember, I have just spent several years in the relative comfort of a Lightwing.

 

 

[Guest Ken deVos]

reposted in this thread

 

I also had a strange experience in a 170 while practicing a full flap baulked landing at about 500 feet.

 

In this case, when full power was applied, it appeared that the elevator lost authority and I could not hold the nose down with full forward stick. The nose continued to rise and airspeed kept dropping.

 

Ultimately, I pulled power to let the nose come down, then gingerly re-applied power.

 

I couldn't repeat the effect on subsequent attempts. :raise_eyebrow:

 

see..

 

http://www.recreationalflying.com/forum/jabiru/10766-j170c-full-flap-baulked-landing-characteristics.html

 

 

[Guest ozzie]

possibly i am out of line here(again) not having flown a Jab but the thing that jumps first to mind is TRIM setting.

 

does the jab have trim?

 

 

[turboplanner]

Ozzie there is trim, but these incidents relate to HF situations where full flap was left on for take off.

 

The Jab has very good flaps, and full flap has a heap of drag.

 

 

[Guest Ken deVos]

Trim

 

Ozzie, the trim on a jab is a spring/friction lever that can be overridden with the control stick.

 

 

[Guest ozzie]

Ok then first thing i would check is this overriding function. obvious the problem is here. Hell sounds scary as.

 

 

[Guest Ken deVos]

Ozzie, the trim lever simply moves forward when full forward stick overrides it.

 

In my encounter, I'm assuming that the elevator/ H-stabilizer was past the point of stalling.

 

 

[GraemeK]

can be overridden with the control stick.

... and fairly easily. Our run-up checklist has "takeoff trim SET" before "controls full free and correct". In doing the latter, it changes the trim setting .......

 

 

[Guest Qwerty]

Destiny, re-read the post...Ken had the stick full FORWARD as I did.

 

I suspect that the ELEVATOR was stalled (the wrong way). The elevator is designed to provide a DOWN force but in this situation you want UP force and cant get any because the elevator is stalled the wrong way round.

 

Have I got this right? Is this what happened??

 

 

[skybum]

It is a simple error that can have serious complications. Cessna reduced the flap deployment angle of the 150 to the 152 from 40 to 30 for exactly this reason.

 

TRAINING! Go round from a full flap approach is nose down and power followed by an IMMEADIATE reduction to half flap...What's the count in a jab? A counting to three? On the ground and inter-circuit? TRAINING! Do not rush your intermediate pre-takeoff checks. Do not bash yourself over it, everyone does it eventually.

 

 

[BigPete]

About three years ago we had quite a nasty accident here at Echuca. A visiting Jabiru (SP 6 cylinder - I think) decided to go around just before touchdown - full power applied, and then removed full flap - poor little bus fell like a stone and broke up rather spectacularly. :yuk: Occupants suffered some back trauma and cuts and bruising. :black_eye:

 

These days with electric flaps (which are a lot slower than the old manual type) you get enough warning not to contine with it. :ah_oh:

 

Qwerty - you did well, another lesson learned and experience gained. :thumb_up:

 

regards

 

 

[Guest Qwerty]

Destiny, I suspect that you are on the wrong track here. My a/c (wing) was not stalled. From what Ken was saying neither was his. It appears that the elevator was stalled in lift (as opposed to down force, its normal function) due to the unusual forces applied by the combination of engine thrust and flap drag.

 

 

[Guest Ken deVos]

Destiny, re-read the post...Ken had the stick full FORWARD as I did. I suspect that the ELEVATOR was stalled (the wrong way). The elevator is designed to provide a DOWN force but in this situation you want UP force and cant get any because the elevator is stalled the wrong way round.

 

Have I got this right? Is this what happened??

Querty, you are correct!

 

I had just finished a practiced forced landing with the nose at a low angle, then at 500ft, applied power while slowly pushing the stick to fully forward to stop the nose from lifting above level, but the nose just kept rising.

 

I think the wings were far from being stalled, but that the stabilizer/elevator was indeed stalled. If I had let the nose continue to rise, then yes, the wings would then have stalled.

 

 

[Guest drizzt1978]

My first instructor (Eugene Reid), drummed a few things into me, one was a go around with "accidental" full flap. (some from wheels on and some from a few feet off the ground) and how to rectify it, basically stick foward and loose half a stage ASAP, if my memory serves correct.....

 

 

[kevinfrost]

A WORD OF CAUTION TO PILOTS

 

Most of the planes we fly in Aus are well designed and structurally sound if flown within their design parameters. All a/c fly differently depending on design and wing configuration. If you fly it , get to know it. "A WORD OF CAUTION ABOUT A PARTICULAR AIRCRAFT". No, just HUMAN FACTOR.

 

 

[Guest Ken deVos]

Destiny, your input is very welcome.

 

Drizzt1978, I'll keep that in mind for the 170 in future.

 

Perhaps if the 170 had full tanks instead of about 85litre, the wings would be less effective at raising the nose, but the converse would also be true. I also had no baggage in the back, so if fully loaded with 36kg, it would make it worse.

 

Querty, is your aircraft an SP with fuel in the wings?

 

 

[turboplanner]

"A WORD OF CAUTION ABOUT A PARTICULAR AIRCRAFT". No, just HUMAN FACTOR.

You're right Kevin, it's a human factors issue, can really only occur when you stuff up by getting distracted, and the fix is to bring it up the scale of importance in your subconscious.

 

 

[Guest Ken deVos]

Human Factors

 

You're right Kevin, it's a human factors issue, can really only occur when you stuff up by getting distracted, and the fix is to bring it up the scale of importance in your subconscious.

Yes, it is Human Factors.

 

In my case, more, me thinks, an example of the SHEL model than a slip caused by distraction because I purposely put the aircraft into that attitude and configuration. Perhaps, for you TP and Querty, it was an attention slip, or lapse of memory? :big_grin:

 

 

[turboplanner]

There's no doubt it was with me, and I've forgotten what Qwerty told me..

 

 

[Guest Ken deVos]

Destiny, with my limited experience and training, I think I agree with your post.

 

However, the question in my mind is why did the elevator stall before the wings, if this is what happened?

 

Consider also, that the elevator should gain extra authority due to the prop-wash when power is applied.

 

There is also the issue of turbulance over the elevator caused by the prop-wash and full-flap.

 

 

[Guest Qwerty]

Hi, Im still not happy that I fully understand what happened. The cause is easy, dipstick me took off with full flap. What happened is another matter.

 

The situation was;This is a 6 cyl SP tail wheel Jab with Pilot, 80 litres fuel (behind the seat), No pax, No luggage. full power from the threshold with full flap.

 

The a/c left the ground very quickly and commenced an ever steepening climb. Full forward stick did not counter this trajectory. Slow retraction of flap corrected the situation.

 

This all happened in a matter of seconds. I don't know that the elevator was stalled but it certainly didn't have the power to counteract the moment couple of the 120 hp going flatout and the drag of the full flaps.

 

It seems that Ken experienced the same thing in his J170.

 

Someone posted that he thought that we were both headed for a low alt stall and This is certainly correct.

 

Destiny, I fully understand what you say about 16 deg AoA and if you reach 16 deg you stall. On the otherhand you can only get to 16 deg AoA on the wing with the stick full forward at low speed, ie. stalled elevator. I was at about 70 kn with a normal load with the stick full froward. I cant see that it is possible for the wing to be stalled in this configuration, as you say irrespective of the attitude or direction of travel.

 

Maybe the elevator was in the dirty air off the flaps???

 

Any further thoughts??

 

 

[flying dog]

Hang on.

 

A tail dragger Jab?

 

So, with full flap, you got the backside off the ground then started a steep climb?

 

That is confusing.

 

Because to get into a steep climb, the backside would be down - probably on the ground.

 

However, as it has been said by a couple of people already:

 

You learnt something and are not dead. That is good.

 

Whether it was stalled flaps, or "what ever", you felt what the plane was doing, reacted correctly and it works/ed.

 

"Next time" you will know what is happening sooner and avoid it. THAT IS WHAT MATTERS - in my opinion.

 

Sure, it would be nice to know the full story, but I would suggest YOU do the leg work and talk to your instructor - who saw this happen, right?

 

I am saying this because other people haven't seen what happens, and though you are explaining it as best you can, the old "Chineese whisper" problem occures and this compunds the error/diagnosis.

 

Fly safe.