Take off distance in j4xx

[Roel]

Scary to think, taking off from FAKR (5500ft) on a relatively hot day (27deg), giving a DA of 8100ft, 3 adults (one heavy (me!) and my 2 daughters (not so heavy fortunately!)) plus 75% fuel on 378kg empty ( I would guess overall close to 730kg) and going uphill in a +-7kn headwind - this all on a 800m runway......
I was sweating towards the end of the runway and it was not the heat...

If I read your graph correctly it says 750m for a flat runway. Add the initial slope on 08 at FAKR and I would say that was damn close. I had to wrench it off the ground and over the fence.

Don't underestimate what it takes. Your graph is an excellent guide, thanks Ben and everyone!

Roel

[BigglesSA]

Hallo Roel

I must say that with every takeoff I am also getting more and more convinced that Ben's graph is as close as it could get with enough save margin!

Thanks for the feedback!

[ZuluBen]

Hi Roel

Yup, at the Highveld, with a bit of temp, be very carefull, when you are heavy you are going to need 800m, just to get off the tar, and NO trees at the end either ..

And before you start your take off roll, have your Go / No Go markers clearly identified, you have no chance of stopping if you want to abort at the 700 m mark ..

Better fly early mornings, makes a BIG difference

After take off, the trick is to get the speed above 80, so very carefully "milk" the flaps away in small increments, keeping the nose down as much as you can get away with.

Once established above 80kts, she seems to "forget" about the MAUW issue ....

I often fly at MAUW, but only from a looooooonnngg runway

[henk-indabush]

Scary to think, taking off from FAKR (5500ft) on a relatively hot day (27deg), giving a DA of 8100ft, 3 adults (one heavy (me!) and my 2 daughters (not so heavy fortunately!)) plus 75% fuel on 378kg empty ( I would guess overall close to 730kg) and going uphill in a +-7kn headwind - this all on a 800m runway......
I was sweating towards the end of the runway and it was not the heat...

If I read your graph correctly it says 750m for a flat runway. Add the initial slope on 08 at FAKR and I would say that was damn close. I had to wrench it off the ground and over the fence.

Don't underestimate what it takes. Your graph is an excellent guide, thanks Ben and everyone!

Roel

Roel
thanks for posting this. I hope everyone reads it and take it in.
MAUW at density altitude 8100 ft with slight uphill 800 m runway - I will not attempt it. I did when I was a youngster and learnt my lesson. Now I am a coward. But there's only one way to fill the expereince bucket, and I am glad you are doing it; with the aid of Ben's graph. It is an invaluable tool.
And I do hope the blik-aerie fans (who seem to know all the limitations of a Jabbie) also read this - the jabbie is an awesome plane.

[jetjr]

Digging up old thread
This data has me coming back looking for info on J200/400
Any ideas on extra distance required?

[BenSmit]

I am sure we can dig out the old graphs and make it fit if I have the POH data

On the J430 graph, we did the math, then a number of guys like Zuluben, Henk, BigglesSA and others did tests in various conditions to prove up the numbers, and we were very close.

I believe those numbers are accurate if you want to calculate a safe take off.

[BenSmit]

I went back to the original calcs and I did actually have a stab at including rwy slope but I had not developed that part well enough to share. The calc suggests that roel would have required 790m for take off.

The calc takes into account DA, weight, wind and rwy slope. Standard J430 (no fuel injection) with standard factory prop.

[jetjr]

For the j200 there's different info out there
POH says 350m, at 100' field height, unfactored,
Add 115m for each 1000' pressure altitude
This is to 50' height.

Specs from SA seem to have TODR way shorter even on j200/400 spec sheets
From my digging it seems shorter wing may require 14% more take off distance
Do you guys even have this short wing version??

[BenSmit]

Jetjr, Without the benefit of of actual tests it becomes a bit academical but I will give it a shot. I dont think I have seen a shorter wing here in SA.

[BenSmit]

Ok so I will stop hogging this space now. This is the excersize:

Roel took off at FAKR at 730kgwith DA of 8100ft and a 7kt headwind. I think that FAKR has a 0.8 deg upslope (thats what I get when I measure alt and distance between the thresholds on google earth anyway) Look at the graph below and follow the steps and the red line. It says he would have needed 810m for take off (safety margin included)

[BenSmit]

Here is the clean graph. Remember this is indicative only and does not supercede the POH

[Roel]

Looks like an excellent guideline, thanks Ben!

[PineATC]

Thanx.. .now.. add an expected ROC....at certain altitudes (80 kts)...running out of paper width.

[AJW]

I have a habit of video taping my flying. The GoPro is ideal, but not always with me.

I have started to check my landing and take off distances by plotting them on Google earth. My info ( weight/ density alt/ wind ) not always accurate.

If anybody else does the same, why don't we post info here?

I have now checked my last two take off and compared it with the above graph. Info not 100%, but will in future....

Prop RPM 2850 static.

Nr 1: Grass runway, downhill slope with wind from behind +- 5 kt. Take off weight +- 600kg. Density alt 2500ft ( runway 260 ft ).

Graph: 460 m
Real: 460-470 m. Unfortunately this is from video taken from the ground, not GoPro....

My landing was about 280 m, no wind, slightly uphill applying brakes. But this is from threshold till turning around. Could not use the threshold due to high sugarcane, so can deduct 10 or 20 m. This is a bit to long to my liking.....

Nr 2: At Richards Bay, tar. Slight up slope, wind +- 10kt density alt 1500 ft. Weight +- 550kg

Graph: 325 m
Real: 250 m
Landing: 350 m, no brakes

[BenSmit]

Thanks Abrie

Remember the graph is fundamentally based on the POH data and then refined by testing, which means that grass runway forms the base. Your grass take-off is close as vark to a swearword

Obviously tar surfaces give better performance, but that was pretty good!

As this information comes in I will refine the data