J120 drops oil @ YCRG. Very lucky timing

[facthunter]

IF you come in at the "real" minimum speed on a Jab ( any of them) they will dump onto the ground and not roll very far. Trouble is , they are not an easy aircraft to do that with, requiring some fairly precise judgement and some quick reaction. IF the strip has some undulations in it you introduce another factor and uncertainty. If you are NOT comfortable don't put yourself into a corner. A jabiru at slow speeds needs good pilotage and there is not much margin for error. Most people don't go there. Nev

 

 

[jetjr]

I agree FH, aircraft is pretty good for short field BUT not many pilots, inc me, are good enough to pull it off

 

POH says 250-300 m i think

 

 

[motzartmerv]

From the 17@ poh.

 

Take off distance at sea level on a 20 deg day at mtow is 464 meters on bitumen. No slope.

 

Landing distance same conditions is 464. What a fantastic coincidence hey? Or fudged numbers?? Anyway, if that's how much room the test pilot needed on a bitumen runway in good conditions, then 600 m would need to be assessed very carefully on the conditions that maj mentioned earlier. And the Imortant thing here is that we aren't flying to defend out country or evacuate injured people here. It's supposed to be fun!!!

 

 

[jetjr]

J170 and J160 would be similar distances, higher MTOW but longer wing on 170 but only 80 hp.

 

These numbers are factored by 30% and only a portion is runway required.

 

Yes landing and take off are similar, in fact landing is more stable number BUT biggest factor is pilot as you say

 

Jut been talking to Jab about these distances and for LSA they have excellent data.......just isnt preesented well in POH

 

 

[turboplanner]

Yes landing and take off are similar, in fact landing is more stable number BUT biggest factor is pilot as you say

Without the biggest factor landing distances can be anything.

 

I've seen plenty of Jabs float way past the 600 metre mark.

 

No doubt on a calm day, a good pilot can hit the optimum touch down spot, but he's not the one you have to worry about.

 

The one that's going to take your house and all your assets is going to be the one who THINKS he can, or the one who did all his training in calm weather.

 

 

[motzartmerv]

I don't agree jet, the 160 and 170 have quite different performance. And the same engine?

 

Takeoff and landing distances are to and from a height of 50 feet.

 

:)

 

 

[Nick Evison]

Here in overcast england a few jabs with low hour pilots regularly get into the 390m farm strips at Clench Common. I trained here and find short field landings a breeze but get intimidated at larger airfields with more radio and traffic to contend with. Training is the answer.

 

 

[facthunter]

Training IS the answer. Pilots who train at big airfields tend to get slack and add a few knots for mum, and get used to using more runway than they should need. Jabs will float for ever if you are a bit hot and especially if the idle speed is a bit fast. Very few people get the mains on close to the (first) fence. Nev

 

 

[motzartmerv]

Wow. 80 meters shorter than the jab poh numbers. ;)

 

 

[facthunter]

Colder thicker air . Slower G/S ??? Nev

 

 

[motzartmerv]

Jab have figures in the minus centigrade. ;)

 

 

[Nick Evison]

nope summer time nil wind conditions too. had a few eurostars take out the fences before. no jabs as yet.

 

 

[DrZoos]

Got to agree with Nev. If you have a long runway you need to practice short landings and slow landings. Its so easy and comfy to come in hot and chew up runway slowing the aircraft. Even in a floaty jab if the speed and height are right and the approach is clear you should be able to hit the spot with practice. And if your in a jab that you call floaty all the more reason to get it right, because one day when them trees or fence are coming at you, you just may need to know how to have a non floaty jab.

 

 

[Guest Maj Millard]

Float is often a product of too much airspeed into the flare, nailing the correct number on final and maintaining it with a bit of power is the trick. Once over the fence bring the power back, and she should drop on. Generally referred to as 'dragging it in on the power'.... It's also inportant as soon as the mains are on to get rid of the flaps, to reduce lift/ float and to assist the braking effect.

 

Short field ops are really skills that needs to be honed, and practised often. It really gets you in tune with your particular aircraft and its capabilities also............Maj......

 

 

[Bruce Robbins]

Wow. 80 meters shorter than the jab poh numbers. ;)

The English Jab is a different model, based on the SP, and with lighter MTOW, thus has better performance than our 160/170's.

 

 

[facthunter]

The technique is really a "precautionary " approach using power to regulate precisely, your approach path and speed. Plenty of people in this movement don't like power assisted approaches, but if you really want to nail it onto the end of the strip it's the only way for the Jab. On a DH 82 you can use interrupted sideslips right to flare, combined with a slipping turn if needed, at the right place, but these are all critical manoeuvers and need the right technique and plenty of practice

 

 

[turboplanner]

Of course you can FH but it's the clowns who make a habit of not bothering about approach speed or short field technique, or even which way the wind's blowing that make it necessary for a property owner to make sure he has a very comfortable margin.

 

 

[biggles]

Not sure how this thread drifted so much but here goes ......... Getting into a short strip is one thing , but getting out may be another . Some time ago I flew into Farri's property , just South of Cairns in the fully loaded J160 . The very scenic strip is grass , level , 500 metres long with cane fields at one end and vegetation at the other . The orientation is generally east/west and the wind when we arrived was a gentle Southerly .I figured the grass would assist the landing roll , and probably touched down about 150 m past the threshold to clear the vegetation . I finished up having to add some power just to get to the turning node . Getting out , a week or so later presented a totally different scenario , and , as we know , just about everything grows rapidly in that part of the world after a shower of rain . I walked the strip with the GPS to see if maybe one end was favoured , but no , no difference in level , and the grass still damp with that gentle , and unhelpful , Southerly again . Having regard to all the prevailing circumstances I made to decision to offload my 'navigator' , and Frank obliged by driving her to Innisfail airport , a few km South . I guess the point I make is that each take off and landing must be carefully assessed , having regard to all the conditions existing at the time . We shouldn't assume that because we landed at a certain place , in a certain aircraft last month , that it is necessarily safe to do now . Don't put yourself under any pressure , the sort of flying we do should be pleasure able and, above all , safe . I have no doubt that had I attempted to take off fully loaded , in those conditions in the J160 with its 80 HP engine, I may have been a statistic , whereas a 6 cyl Jabiru would have done it easy .The attached thumbnail shows me finally departing Franks strip ,heading South for the 15 min .flight to Innisfail.

 

 

 

[motzartmerv]

Too right Biggles. Great example of airmenship with a real chance for a gotya. You could easily been sucked into a false sence of security after landing short on that strip. Thanks for sharing.

 

 

[crashley]

yeah smart decision bob assess each take off and make a decision based of the conditions at the moment not what it was like last time or even last week

 

 

[jetjr]

I don't agree jet, the 160 and 170 have quite different performance. And the same engine?Takeoff and landing distances are to and from a height of 50 feet.

:)

I reckon they would be similar, you might be forgetting one is Ok to just 540kg, other to 600kg

Same engine different wing, same debate for J200 and J230, shorter wing less likely to float on landing too.

 

From POH's, 20deg at ~ sea level

 

160 TOD is 464m (Ground roll just 210m)

 

170 TOD is 475m

 

AND these are factored 30% (not actually mentioned in 160/170 manuals but is in 200/230) which accounts for 80m less indicated above

 

Add some heat, height and low pressure and things get ugly quickly.

 

 

[motzartmerv]

Yea jetr. I often giggle at those figures as im lifting off in the 170 in about half the distance the 160 takes. We often take off in company aswel so a direct comparison is easily made. Jabs figures are all over the place im afraid.

 

 

[jetjr]

I dont disagree and the issue is close to my mind right now - see thread on building my own runway.

 

Which aircraft is closer to its POH numbers?

 

I spoke to Jabiru engineer and for LSA versions they really have tested these numbers, seems they are leaning towards reducing information provided in POH so pilots make the decision on their abilities rather than a theoretical numbers they provide. All agree most pilots have trouble getting them down short so publishing optimistic data is not a great idea.

 

Theres some guys that believe VG kit can reduce J160/200 TOD by 100m? Sure drops stall a good 5kts.

 

Only way to couple all this together (+ your abilities) is to test fly at the height and weights you plan on going to shorter fields. Need info on ground roll as much as 50ft too it seems..

 

 

[Ultralights]

i am currently studying Aircraft performance for CPL, the amount of info needed to get accurate numbers is quite huge! and also, while researching RV10 aircraft ownership and building, some owners during their 25 hrs flyy off restricted area flying, do nothing but performance testing to get the data for their POH's. some of the data those builders/pilots get makes the Cessna POH data look sparse by comparison. its proven that it doesnt take long to get good accurate data required for pilots to make accurate assessments of the aircraft performances in all situations.

 

All agree most pilots have trouble getting them down short so publishing optimistic data is not a great idea.

When it comes to published operational data, there is a Mandated percentage the numbers have to be increased by to factor in poor pilot performance, and older worn aircraft. CASA mandates between 15% to 25% based on the MTOW for takeoff distance required and landing distance required from 50ft. but reality is, a lot of pilots fly the aircraft too fast for landing to get it close to, or on the numbers,

 

 

[Guest Maj Millard]

I dont disagree and the issue is close to my mind right now - see thread on building my own runway.Which aircraft is closer to its POH numbers?

I spoke to Jabiru engineer and for LSA versions they really have tested these numbers, seems they are leaning towards reducing information provided in POH so pilots make the decision on their abilities rather than a theoretical numbers they provide. All agree most pilots have trouble getting them down short so publishing optimistic data is not a great idea.

 

Theres some guys that believe VG kit can reduce J160/200 TOD by 100m? Sure drops stall a good 5kts.

 

Only way to couple all this together (+ your abilities) is to test fly at the height and weights you plan on going to shorter fields. Need info on ground roll as much as 50ft too it seems..

Cessna managed to get their POH figures very close to accurate in my experience....why can't Jab ?...Published stated figures are important as a starting point for each aircraft, and really that is what the Pilot Operating Handbook is all about isn't it ?...................Maj......