Couple of Jabiru Questions

[Harthy]

Thruster

 

Yenn,

 

50knt approach, 45 - 50knt climb, 55 to 60 knt cruise or 50knts just poking around on a Sunday afternoon.

 

Harthy

 

 

[Guest Ken deVos]

I dont really understand this: Why limit flap in turbulence? Isn't it better to still use flap but maintain IAS at the higher end of the full-flap range? Say 70kts approach and ease to 60kts late late final.. I use this approach in all conditions and never use more than 50% of my 640m one-way strip..And do not pound the undercarriage

Progressive flap application initially increases lift more than drag, then drag increases more than lift until at full flap extension. My understanding for limiting the use of full flap on approach to land in turbulence is that, you want the extra lift to reduce the stall speed, but to better penetrate the turbulence, you do not want or need the extra drag of full flap.

 

Anyone agree with my thinking here?

 

Another related issue is that some aircraft have a lower flap extension speed for full flap and this may prevent you increasing your approach speed for turbulent conditions.

 

 

[Guest drizzt1978]

Progressive flap application initially increases lift more than drag, then drag increases more than lift until at full flap extension. My understanding for limiting the use of full flap on approach to land in turbulence is that, you want the extra lift to reduce the stall speed, but to better penetrate the turbulence, you do not want or need the extra drag of full flap.Anyone agree with my thinking here?

 

Another related issue is that some aircraft have a lower flap extension speed for full flap and this may prevent you increasing your approach speed for turbulent conditions.

My experience in j170

 

This is what we have just adopted at Tooradin, With a strong head wind and full flaps, you gota "drive it in" Ie more power than you want, And its just doesnt "feel" right, But half flaps with head wind or turbulence is so much more civilized.

 

I learnt full flaps all the time, but changing instructors and a few other things, this is what they teach, and I find it SO much easier to land!! (and approach)

 

 

[Burlc]

Thats right Drizzt1978. You made a good point about changing instructors, if it does'nt feel right it probably is'nt right.Changing instructors could be all that is needed to restore confidence in your flying abilities,worked for me early in my training and has made me a more confident and safer pilot.

 

Landing in turbulance and or with rotors off trees and hangers less flap to no flap is the best way for me especially in a crosswind,plus 5kts extra speed.

 

My normal approach is 70 kts.

 

Quoted from the book: In turbulent conditions,it is advisable to carry a few extra knots on approach to give you better controllability. A flapless approach should be considered, since it will make the aeroplane more responsive to a power increase due to the lower drag. End Quote.

 

Plus with less flap, less wing area for the gusting wind to grab onto stabilizing the approach, less fighting the aeroplane, less pilot stress, better approach= better landing.

 

Having flown both the 160 and the 230 the 230 wins the best jabiru to fly.

 

Why? More power, better climb, faster cruise + with the bigger wings more stable in the bad air. This is what I have found.

 

 

[Guest brentc]

Hi Daniel, the J450 is a bigger wing than the J430.

 

From what a builder of one told me at Narromine he said his stalls at around 37-38 knots at max weight (544kg's), versus more like 42 for the J430 @ 544 kg's. I'd have to check the stats for the exact figure.

 

Apart from the wing, same aircraft as the 200, 400, 230 and 430. There are some other minor differences to the cowls between the 2/400 models and 2/430 models however later 2/400's had these cowls anyway from what I can tell.

 

The biggest benefit of the J250/450 is that when 760 comes along, you will actually be able to go over 600kg's because the stall speed is lower than the 430. As for how much higher, I am unsure but it would have to be atleast 50kg's you'd think.

 

 

[mAgNeToDrOp]

Correct me if I am wrong - this is from memory - but the mtow of the J160 isn't 544 but 540kg because they couldn't get it to stall at 45 knots or below at 544kg, but at 540 its fine...?

 

As for the reason for the post I enjoy the J230 - simply for the grunt , climb and sound of that six up front ;) Still love flying the J160 but was definitely a bit harder to learn on..but worth it..

 

I found I floated alot at first but I had a tendency to come in a little fast - full flaps made it easier to control the speed and for better landings but obviously watch that speed ;)

 

 

[Relfy]

I've also found the J170 more comfortable to land in turbulent conditions, with 1/3-2/3 flap. Full flap in light winds is nice but when it gets a bit rough and sideways I found that with full flap I was more susceptible to sideways drift on round-out and flare.

 

 

[Friarpuk]

I'm not sure if anyone has asked this question of you Pioneer200, but what type of approach are you making?

 

My instructor has 18 000 hours flying in PNG and Agwagons in Qld and teachs his students in 120s, 160s, and 230s to come over the fence at 70, half flap turning onto base 1000 agl, keeping the aircraft at 70 kts and -500 vs, turning final at 500 agl, then full flap once committed to land. The only variation is in turbulence where we add 5 to 10 knots and stay on half flap or clean if it's really rough.

 

Last glance at the instruments before roudout settling down to 65.

 

If you are making a glide approach I can understand you might float down the strip and scare yourself. But if you are using power to drag you to the strip then the only floating you will do is on the round out.

 

I understand many are taught to make glide approaches increasing the chance of floating in ground effect. But being an Ag pilot my instructor has taught us to come in lower with power.

 

fwiw

 

 

[Guest Ken deVos]

Correct me if I am wrong - this is from memory - but the mtow of the J160 isn't 544 but 540kg because they couldn't get it to stall at 45 knots or below at 544kg, but at 540 its fine...?.....

mAgNeToDrOp, 540kg MTOW is also my understanding of the J160 specs for a stall speed of 48 KIAS in the landing configuration which translates to 45 KCAS as shown in the POH.

 

Note that the LSA requirements for Part-103 stipulates a 45 KCAS stall speed in the landing configuration at MTOW.

 

 

[Guest Ken deVos]

That's easy then, the White arc is not the stall speed, it's the flap extension speed. I'd say it's just poor documentation as it's definitely not above 45 knots. Why am I not surprised with that :-)At a really rough guess it would be maybe 44-45 knots. Mine stalls with the same wing at 45 knots at 544 kg's, so perhaps around the same because of the wing.

Brent, you have me wondering about these figures.

 

The J200-B can be registered in RA-Aus, but not the J200 because, as I understand it, the stall speed exceeds 45 knots.

 

Are you saying that your J400 aircraft has the J200-B wings?

 

Also, can you tell me what is the difference in the wings for the J200 and J200-B.

 

 

[Guest brentc]

Ken, from the horses mouth, so to speak:

 

The J200 A was the GA model with MTOW of 700kg's and 48'ish knot stall.

 

The J200 B was the RA model with MTOW of 544kg's and 45 knot stall.

 

- They have the same wing.

 

J160c is a 45 knot stall @ 540 kilos which is the certified MTOW.

 

J160 (kit built) is a 45 knot stall @ 544 kilos.

 

Why is it 4 kilos less? Because on the day it needed to be 4 kg's lighter for them to get it to stall at 45 knots exactly ! CASA were waiting, charging by the hour and everyone wanted to go home.

 

Certified models are rated at a stall speed of 45 knots CALIBRATED speed.

 

So the J200 is RA-Aus registerable as it stalls at 45 knots at 544 kilos.

 

Unfortunately when 760kg's comes along, the J200 can never be loaded more than 544 kg's, same goes for my J400 :-( If I were to sell mine with a higher MTOW than 544 kg's, I would lower the flaps and add vortex generators. Not sure what that would give me in stall speed exactly, but might give me another 50 kg's.

 

Same goes for the J230 at 600kg's, unfortunately it can't go higher than 600 kg's because of the stall speed, however on a homebuilt model, lowering the flaps and adding vortex generators would give some added kilo's of baggage.

 

 

[Guest Ken deVos]

Thanks Brent, it can be very confusing with KCAS, KIAS and different MTOWs.

 

On wings and the J250/450, I noticed from early and later photos that winglets are a new addition. Perhaps maybe, as you have stated elsewhere, the J250 will cater to the 760kg MTOW requirements. Any news of Jabiru certifying this model?

 

 

[Guest brentc]

I hadn't noticed winglets not being on the 250/450 as I never saw one until Narromine this year, although I note from the latest RA mag that there was one in Narromine in 2007.

 

I just wrote a detailed response only to find the answer is on their website!

 

J250

 

Stall Speeds at 700kg

 

Vso (full flap) 45 kts (52 mph)

 

Vs1 (clean) 50 kts (57 mph)

 

http://www.jabiru.net.au/J250J450bodyFrame-1.htm

 

So there you go, in theory it looks like if 760 comes along you can go with a 250 up to 700 kg's.

 

I can't say for sure of course, however I can't see that the 250 will ever be certified at a higher weight than 600 kg's because it would cost a fortune because it would need to be properly certified (eg. 95.55) rather than LSA because LSA is only 600kg's, so very unlikely I suspect whilst LSA remains at 600kg's. It would probably cost mega-bucks, like a million even. Someone once told me it cost $1.5million to certify the J160, but that may not have been true. If LSA was around it would have cost practically nothing in comparison!

 

 

[motzartmerv]

Yea, keeping it clean and fast in the chop is advisable.. It will respond to power/ attitude changes faster then at full flap..

 

Friarpuk, are you being taught to turn final at 500??...or complete the turn BY 500??...just curious...