Take off distance in j4xx

Australian designed and manufactured Jabiru Aircraft/

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BenSmit
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Re: Take off distance in j4xx

Unread post by BenSmit » Sat Apr 03, 2010 9:34 am

How does this work? Check the example below.
1. Pick the DA
2. Follow that line to your AUW and note the distance
3. Take the line across to the wind factor graph to the 0 wind point, now follow the line up or down to the current wind component
4. Read the distance

Check the red line
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Re: Take off distance in j4xx

Unread post by BigglesSA » Sat Apr 03, 2010 4:31 pm

Ben, wizard is all I can say!!!!

Guys I plotted some of our raw test data and it is practically spot on. Well done Ben. Now we can go test this graph against all our take-off rolls up here and the guys at the coast. I am glad to see wind factor starts at -5 as some fields are one way in and one way out.


Ben =D> =D> =D>

FYI, Phillip took of today at Brits (3740ft) for Wolmaranstad 3 adults and full tanks....5kg over max downhill and approx 5 knots down wind and was airborne at 650 meters.
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Re: Take off distance in j4xx

Unread post by BenSmit » Sat Apr 03, 2010 5:54 pm

What would the DA have been? if I make an educated guess then the graph is pretty close

Now to add runway slope, but first I need to know that the data here is spot on. Also this test data is for Tar, we need to see how grass influences the data
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Re: Take off distance in j4xx

Unread post by BigglesSA » Sat Apr 03, 2010 7:22 pm

Ok Ben try this for size:

Phillip's run today!

Brits 3740ft
QNH 1018
OAT 25 deg
DA 5572ft
RW 20 slight down hill.
Wind approx 2-5 kts 200 deg (so downhill cancelling downwind somewhat)
AC weight 710 kg TOW
Run approx 650 m

Plotting your chart at zero wind give me 650 take-off run. Airborne in a non measured 650 meters. Could just as well have been 640-660 meters. Close enough for me!!!!!!!!!!!


Ben your onto something here boet. I have already printed this chart and will laminate as to re-use it. Feedback as I get it!!!!

I think everyone should do the same testing of Ben's chart and provide him with this kind of feedback. Exiting stuff!

Ben Thanks so far, and that between your studies :lol:

What is this release called? Chart version Beta 1.0.1?
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Re: Take off distance in j4xx

Unread post by Phillip-G » Sat Apr 03, 2010 10:13 pm

BigglesSA wrote:Ok Ben try this for size:

Phillip's run today!

Brits 3740ft
QNH 1018
OAT 25 deg
DA 5572ft
RW 20 slight down hill.
Wind approx 2-5 kts 200 deg (so downhill cancelling downwind somewhat)
AC weight 710 kg TOW
Run approx 650 m
I used 10Deg Flaps - normal T/O Technique, but I let it run a bit further and after rotating kept it in ground effect to build more speed.
AND THATS WHY I LOVE MY JABBI..!!
We flew to FAWD (Wolmaransstad) 1100m gravel Rwy.
Landing and T/O - no problem..!!
What a magnificent A/C...

We are ready for the Botswana Trip..!!
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Re: Take off distance in j4xx

Unread post by BenSmit » Sun Apr 04, 2010 10:47 am

Great feed back, thanks guys, keep it going.

I kept the figures conservative and would be happy if actual performance is somewhat better than the chart - safety margin
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Re: Take off distance in j4xx

Unread post by henk-indabush » Fri Apr 09, 2010 6:21 pm

Great work Ben =D> =D> =D> =D> =D> Exactly what we needed!
I will also laminate it and test-drive it often. Grass most certainly have an influence, I land on grass often. But I think this is excellent and need not any more adjustments.
I am impressed!!
Thanks Ben.
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Re: Take off distance in j4xx

Unread post by ZuluBen » Fri Apr 09, 2010 6:33 pm

Lekka Ben!

So I am guessing that you are studying Graphs then... =D> :wink:
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Re: Take off distance in j4xx

Unread post by BenSmit » Sat Apr 10, 2010 9:32 pm

Hey guys, credit where it is due. I have drawn quite heavily on the graphs in the POH of the Albat(P166S) The italians did a lot of great work in this POH

My calculations were based on the trials/ tests you guys did and I have built in a margin for safety

More to come as we verify the current data
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Re: Take off distance in j4xx

Unread post by BenSmit » Wed Apr 28, 2010 11:16 pm

Hey guys, I know I have been quiet lately (otherwise occupied and all)

BUT have any of you rocket scientists done any verification of our graphs? Some feedback would help refine the data
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Re: Take off distance in j4xx

Unread post by ZuluBen » Thu Apr 29, 2010 1:04 pm

Your DA / Weight / Distance graph pretty spot on, have not really had the chance to use the wind component part yet.

Thanks again =D>
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Re: Take off distance in j4xx

Unread post by BigglesSA » Thu Apr 29, 2010 9:27 pm

BenSmit wrote:Hey guys, I know I have been quiet lately (otherwise occupied and all)

BUT have any of you rocket scientists done any verification of our graphs? Some feedback would help refine the data
Eish, man I knew there was something I forgot for the trip goodies pack. I wanted to laminate one for each plane with a note explaining/asking that the guys test it during the lots of takeoffs on the trip. That should verify it ok!

Maybe, I should just print 20 and take it along and dish it out there!!!!

Ben, thanks for it, hopefully the guys can give you some feedback after the trip!!!
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Re: Take off distance in j4xx

Unread post by BenSmit » Mon May 31, 2010 10:12 pm

Sooooo you lucky flying baasTed's Did anyone do any verfification of our data lately?
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Re: Take off distance in j4xx

Unread post by henk-indabush » Tue Jun 01, 2010 6:02 am

Sadly I did not verify the numbers accurately, since we never measured the ground roll distances accurately. I did look at the laminated version Biggles made for all of us =D> =D> and I can safely say that at MAUW my Jabbie got airborne in less than the given distance each time. That's with eyeballing the ground roll (would be difficult to measure ground roll at international airports :? ). That is including my unexpected early lift-off at Pilansberg :shock:
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Re: Take off distance in j4xx

Unread post by BenSmit » Fri Jun 04, 2010 10:05 pm

Ok Doc, well then I am feeling happier as one would always want a safety margin. Remember the figures should be safe under worst conditions, ie grass runways, wet etc
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