Why are Jabs so damn hard to fly????

[turboplanner]

Nev - Fly one on a cold day in gusty conditions.

 

Jack -If it was as wide as it is long, and made of sponge rubber, I'd be OK

 

Jack I might be wrong but from memory the difference between the 170 and the 230/243 is - shorter fuse and possibly smaller in the tail, and less power. You rarely hear guys complaining about the 230 and 430. The 170 has a wing which in the cold southern air is super efficient just when you don't need it, and not a lot of rudder or elevator authority to do something about it. Much different to the 160.

 

 

[HEON]

I was not that young when I started to fly in Jab LSA...had a bugger of a time. While training the school replaced the LSA with a 160. Better but still not easy. At that time got a flight in Jab 230...easy!

 

I agree the 160 is not as easy to fly as other RAA aircraft.

 

Weather this is good or bad rearly can be related to ones outlook...personally I do not think the lesson is worth the effort...as long as you don't buy/hire one!

 

 

[turboplanner]

Let's put it this way, if you watch and learn you can crutch a sheep quite well, but you probably go fishing in your holidays.

 

 

[Vev]

Turbo,

 

Yes the boom is shorter (about 50cm) on the 170 compared to 230/430 and the v'stab is slightly smaller too as is the rudder by a tad, but they share the same wing.

 

I have flow the 430 a number of times (and yes it is different to the 160) but its about being gentle and patient and not being too hot over the fence.

 

I must admit the 120 and 160 is my fav Jabs of all of them to fly in unsettled conditions, but I do love the big wing Jabs on a hot day out of Roxby Down.

 

Jack

 

 

[turboplanner]

but I do love the big wing Jabs on a hot day out of Roxby Down.Jack

That's what the 170 was designed for, and I'm sure it would be a much better machine in the heat.

 

 

[motzartmerv]

Tubz. Can you ellaborate a little on what your saying?..

 

Cheers

 

 

[turboplanner]

I'm saying when talking about how hard or easy it is to fly Jabs, a lot of generalisation occurs.

 

Better for those who've flown the model to all give their thoughts on the model - if you haven't flown it, you haven't experienced the traits, particularly the 170, which I find quite good until it's wings sniff a gust of wind.

 

The discussion with Jack is about the Moment distance of the vertical stabiliser and elevators, which as Jack says is about 500 mm shorter in the 170 compared to the 230, and let's say that might be 20%, so if the rudder and elevators are the same size, then in the 170 they will be 20% or so less effective, hence the difference in handling, all other things being equal.

 

 

[Ballpoint 246niner]

Motz, I reckon you've nailed it with your answer, as many of you know I own a 120 and teach in Tecnam's. So it's easy to forget if you're either Arthur or Martha- and I'm neither!

 

The Jab likes lot's of airflow, but too much at the wrong time and it's very slippery. Just ask anyone who's tried to get a 230 to land from 70 kts!

 

The Teccie couldn't really care if it's 40 or 100kts, the linearity in it's behavior is fantastic. For those of you who have flown Sierra's you'll know that the Lam wing sacrifices some of these niceties for performance and that's also the decision Jab has had to make- it's all a compromise.

 

The all flying tail on the tecnam gives great authority at low airspeeds, propwash alone gives enough to raise the nose. But compare the control surface sizes on any of the jabs- much smaller ergo more speed required to be more effective.

 

On the flip side you can buy 2 J160's for the price of a new echo, or close to it so is it any wonder there are so many Jab's - theyre really are great bang for buck.

 

They're both very good airplanes, but nothings perfect, so realise the differences, fly them accordingly, and be a better pilot for mastering them both!

 

 

[Ballpoint 246niner]

Shags I keep telling Tomo to come over and I'll take him up in one of or Echo's- one go and he'll forget going to GA!;)

 

 

[Tomo]

Shags I keep telling Tomo to come over and I'll take him up in one of or Echo's- one go and he'll forget going to GA!;)

I might have to do that Neil, if I have time on Saturday I'll give you a yell. I'll be over to say G'day anyway if you're going to be around.

 

Once you've flown something with a Turboprop.... it's very hard to back down!

 

 

[turboplanner]

Ballpoint, you're talking about a 120. It's a giant leap to talk about mastering a 170 when the deciding factor is not the pilot but the external impact of unpredictable airflow

 

Just to be clear, I'm in agreement with Motzart on still wind or conditions most days - I'm talking about when the weather comes up and you run out of control authority.

 

 

[motzartmerv]

Thats interesting tubz. We have a new 170, only been online for a few weeks. So I havn't had the chance to see it in all conditions. Which control gets mushy?

 

My observations so far of it are what i spoke about earlier, the secondary effects of aileron are almost rediculous at low speed. The rudder secondary effects are not as pronounced as the 160, this along with your comments leads me to believe its not as effective as the 160, even though it is bigger.

 

You are right, comparing the different models is like chalk cheese. The 230 is certianly the most benign of the lot, although it has its problems. The worst of which ive come across is its tendancy to wheel stand 1 up if you apply any back pressure at all early in the t/o roll. Then asymetric blade effect induces yaw that the rudder is barely able to overcome...nasty...

 

 

[turboplanner]

Motzarella,

 

What we are talking about is no fault of Jabiru here. They designed the 170 wing for hot weather in Northern Australia where, at the lower air density, people complained about the 160 climb rate. So they fitted a bigger wing with better lift. From what I hear, that has been a big success.

 

It's us that took that model and used it in the southern states where the air is colder, and therefore denser, changing all the design equations.

 

The wing lift under those circumstances becomes much more sensitive to the slightest change in wind.

 

The points about slower landing speeds make sense. I came from years of flying a Warrior, which also had a high lift wing. In both the 170 and the Warrior, a lot of pilots have problems with float, which means more time to be pushed off the strip before touch down. Correct approach speed fixes this.

 

Moz, you mention adverse yaw from the ailerons. The more the adverse yaw, the more input is required from the rudder, so the foot modulation for this has to be learned and made instinctive over time. This comes into play as an issue at times which we’ll see below.

 

Using measurements from the Jab website, and admittedly over-simplifying, we can see reasons for the different flying responses:

 

Wing span on the J170 is 19% greater than the 160 and 20% greater than Tomo's J120, so the moment arm from the centreline to the wing tip is also 19% more on the J170, and therefore the roll leverage is greater.

 

So there’s more chance of a wing tip bouncing up in a gust of wind.

 

In the discussion with Jack, we mentioned the shorter moment arm of the Stabilisers, rudder and elevators.

 

Roughly working off the dimension from the front of the wing to the front of the rear stabilizers,

 

the moment arm on the J230 is 22% greater than the J170, so the so the rudder and elevators travel less for the same result, so are a lot more effective.

 

So when a strong QUARTERING GUST of cold, dense air hits a J170 on final approach at 60 kts

 

(a) see Motzart’s comment on ailerons

 

(b) The high lift wing responds instantly, trying to pitch up the nose, and this is magnified by the greater leverage on the long upwind wing, so roll is added.

 

This combination starts a yaw into wind

 

© Compared to the J120 and J160, the J170 doesn’t have a longer boom, so it doesn’t Handle this situation as well as they do, and it’s easy to run out of control authority

 

(d) The J230 with it’s longer boom is more resistant to this pitch and yaw, and there is substantially more control authority left, so I’d be surprised if J230 pilots ever faced this issue.

 

This over-simplified analysis shows why the different Jab models perform quite differently at times of unstable and cold weather.

 

The million dollar question, in the light of the RA Aus Magazine reports just about every month, is how do we handle it?

 

 

[Guest Andys@coffs]

To a certain extent, given that this sector of aviation is "cheap" aviation for those that cant or dont want to particiapte in the more expensive forms we must all then accept that there will be compromises. In my home life I dont drive a BMW or a Merc because I can live with the compromises that the Ford or Mitsubishi represent.

 

Similarly while I might have liked the idea of a Pioneer 300 or something else that has a substanial additional $ investment required when it came down to it on reviewing those things that were important to me the J230 ticked all the boxes that were important. Having made that choice I live with it and work to be the best that I can in that machine.

 

I may be different to others in that I dont feel the need to go and drive every possible model available and must really wonder how many are there that similarly want to drive, on a regular basis, all the various models? Why would you do that, other than in the early stages where training aicraft availability dictates what you drive, or you are about to lock in to one machine or another? As an owner Im much more likely to allow someone else to take my chariot for a spin if I know they have substantial hours on type, rather than few hours per type over 10 types. (actually thats all BS.Me myself and I get to drive my chariot and no one else..QBE dictates that to be fact!)

 

I have to say that after a number of hours on any Jab (I learnt in the 160) you get to the point that hands and feet work together almost independant of thought to achieve the outcome needed. Whether that results in lots of co-ordinated movement or little becomes irrelevant in that you dont really have to think about it? So Im not sure what the issue is, other than saying in the early stages of transisition to any type therte are a heap of things you habve to consciously work through and that can be painful.

 

I suspect that if Shags or anyone else stuck with the Jwhatever and we came back to discuss this in 6months time the answer would be Issue? what issue?

 

Andy

 

 

[shags_j]

No doubt at all Andy. I Was just curious as to the why it's so damn hard in comparison.

 

Surely these reasons are structural and not related to cost(?) just what I was thinking anyway.

 

 

[Guest Andys@coffs]

Actually Shags I see that it is almost 100% related to cost.

 

For example if the JWhatevers vs the skill required to fly them didnt come out appropriately then we wouldnt see the majority of schools australia wide (RAA space) using them to teach. Equally if the cost side of the equation was OK but they were simply too hard for the average punter to learn to drive then equally the schools wouldnt use them, and equally a T might be easier to drive but the $ side of teh equation mandates that only a minority of schools use them, and must, all other things being equal, charge more for the per hr experience of the students.

 

I do understand what you were getting at, but it isnt structure of the aircraft alone that dictates if it will be a good training aircraft and experience/deployment tells us that in the main you to a certain degree must be either over emphasising the difference between the two, or, as I believe, in a relatively short time they dont come to matter, whereas the $ tied up tends to matter forever....If you doubt that check with my other half, its her BMW that Im flying :<)

 

Andy

 

 

[shags_j]

I was thinking more from a manufacturer side of things. Why would Jabiru make them so that they are a bit harder to handle.

 

In saying that I have been thinking back to the 230 that I flew briefly. I think from memory it was a much more stable platform and not so picky with the controls.

 

In particular I was interest in Turbo's reply showing why these things are so touchy. Interesting reading there.

 

 

[Ballpoint 246niner]

I might have to do that Neil, if I have time on Saturday I'll give you a yell. I'll be over to say G'day anyway if you're going to be around.Once you've flown something with a Turboprop.... it's very hard to back down!

Yep I'm rostered on so see you sat Tomo.

 

 

[Ballpoint 246niner]

You're right Turbo, I have also a few hrs in a local 170, and our conditions and yours are markedly different, I guess the manufacturers only have to meet the demonstrated crosswind performance for LSA testing, beyound that it's you and me as test pilots.

 

My opinion is that the 170 is definately slower in roll response, even with the bigger ailerons, but it does have a larger rudder with better authority. Your experience seems to suggest not enough, combined with the reduced pitch moment dampening.

 

Are things getting hairy in gusts under the tested 14 kts x-wind ?

 

 

[Allegro2000]

All,

 

I learnt to initaly fly in a Jab LSA, I clearly remember my instructor saying; if you can fly this you can fly anything. I strongly suspect he was right. On final I was similar to to a ballet dancer in full flight. I always waited for that kick up the bum that seemed to be a characteristic of the Jab. I now fly an Allegro and come in as if I was on rails. I enjoyed the Jab I think it made me a better pilot.

 

Peter K

 

 

[turboplanner]

Are things getting hairy in gusts under the tested 14 kts x-wind ?

I haven't flown one at an airport with an ATIS, so I spent some time trying to relate crosswind to the limpness of the windsock. Windspeed/direction is one piece of precise information you don't get automatically in outlying airfields.

 

However, thinking it over, I haven't had a problem with a steady crosswind, even when I was looking out the side window shortly after turning final, so wouldn't think my issues happened above 14 kt XW.

 

It's when you are coming in OK and a sudden gust hits and starts to yaw the aircraft, after which inertia can continue the yaw.

 

BTW, someone just PM'd me and said the 230 was the first to get the long wing, to achieve legal stall speed at 600 kg, and I note the J170 is also at 600 Kg.

 

 

[dazza 38]

To a certain extent, given that this sector of aviation is "cheap" aviation for those that cant or dont want to particiapte in the more expensive forms we must all then accept that there will be compromises. In my home life I dont drive a BMW or a Merc because I can live with the compromises that the Ford or Mitsubishi represent.Similarly while I might have liked the idea of a Pioneer 300 or something else that has a substanial additional $ investment required when it came down to it on reviewing those things that were important to me the J230 ticked all the boxes that were important. Having made that choice I live with it and work to be the best that I can in that machine.

 

I may be different to others in that I dont feel the need to go and drive every possible model available and must really wonder how many are there that similarly want to drive, on a regular basis, all the various models? Why would you do that, other than in the early stages where training aicraft availability dictates what you drive, or you are about to lock in to one machine or another? As an owner Im much more likely to allow someone else to take my chariot for a spin if I know they have substantial hours on type, rather than few hours per type over 10 types. (actually thats all BS.Me myself and I get to drive my chariot and no one else..QBE dictates that to be fact!)

 

I have to say that after a number of hours on any Jab (I learnt in the 160) you get to the point that hands and feet work together almost independant of thought to achieve the outcome needed. Whether that results in lots of co-ordinated movement or little becomes irrelevant in that you dont really have to think about it? So Im not sure what the issue is, other than saying in the early stages of transisition to any type therte are a heap of things you habve to consciously work through and that can be painful.

 

I suspect that if Shags or anyone else stuck with the Jwhatever and we came back to discuss this in 6months time the answer would be Issue? what issue?

 

Andy

HI Andy i agree, with you, if i owned a A/c, i would only fly that.Flying multiple A/c, comes down to nessesity, in our case.At Boonah, with 3 technams, all slightly different, and a drifter and Cub.Guys who hire, generaly fly all three tecnams, and some the Cub/Drifter.It all comes down to a/c availiability when Booking.

I have only flown the LSA 55 Jabiru, i have read how different the models are previously.But this has been a excellent thread, with Turbo, and others, explaining the differences. The Teccy's are alot similar, than the Jabbys, are between model to model .

 

 

[Yenn]

If you are a competent pilot you should be able to handle similar aircraft without too much trouble. By similar I mean all the Jabs, or Cessna 150 to 182. No doubt some will handle differently from others, but flying is flying. Most of my time is spent in my single seat Corby, but for reviews I like to jump into something else and usually find it not too difficult. Don't look on them as being difficult to fly, but rather as a learning experience and an ability to have fun.

 

 

[dazza 38]

I learnt to initaly fly in a Jab LSA, I clearly remember my instructor saying; if you can fly this you can fly anything. I strongly suspect he was right. On final I was similar to to a ballet dancer in full flight. I always waited for that kick up the bum that seemed to be a characteristic of the Jab. I now fly an Allegro and come in as if I was on rails. I enjoyed the Jab I think it made me a better pilot.Peter K

HI Peter, i sort of agree, i flew around half of my flying journey to licence in a drifter,the other half in the Jab LSA55.I did find it hard to keep straight, on bitumen at caloundra.To it all came together.As for being able to fly anything not sure on that.Try the Tail wheel skyfox.Its at another level, maybe not harder, but different.Never flown one but suspect a Pitts would be another level again, being short coupled with heaps of power.

Thats what i like about flying, cars are similar,between one to the other, bikes are similar between one and the other, etc. But aeroplanes, some are very different to another.Cheers

 

 

[pilotdave69]

This is a great topic for those learning in a Jab 160 like myself (12.4 hours so far) . I do agree with many comments of the landings of Jabs. I have only done 5 hours of circuits and certainly feel that its a complex feet, stick movement all the way down . Ive heard the saying, if you can fly a jab, you can fly anything.

 

On Tuesday we had many more circuits, i managed 3 pretty good landings, then the next i ballooned terribly and we did a go around, well the instructor did. Amazing how quick things can change and how a good landing prior can turn bad the next one. I got my composure back and went for another round, again not as bad but still tricky getting that last phase of holding nose wheel off, correct throttle position etc.

 

I do admit i love the Jab 160, not that i have been in anything else as yet, the club has a 230, which i will experience when doing Navs. I guess its what people get used too.

 

Keep up with the good topic, interesting reading . !!

 

Dave