View Full Version : J.31 Jetstream runway performance ?


Kiwiguy
27th Dec 2007, 23:25
Could anybody help me please with runway performance for the non enhanced J.31 Jetstream ?

At 7,000kg AUW, ISA sea level the beastie gobbels up 1,440 metres (4,724 feet) but I want to fly from 1,300 metres with fuel for 600nm (635 kg fuel).

(apologies I previously cited 3,000m in error)

What sort of payload will I get from a 1,300m sea level strip ?


Also is anyone aware of a Jetstream website with the relevant graphs like that which Boeing provides for it's models ?

The BAe website is pitifully short of detail.

Seasons Greetings all



Mad (Flt) Scientist
28th Dec 2007, 00:38
Isn't 7000kg basically maximum weight for the J31? In which case that extra 1600m or so will gain you zero extra payload.

Looking at the J42 data on the baesystems website (http://www.regional-services.com/pdf/Jetstream_41_General_data_brochure.pdf) suggests that the J41 stops being runway limited at 1750m or so (depending on engine power and, although not shown directly, OAT and altitude). I'd be shocked if the 31 were worse. So for a 3000m strip your available payload will be simply your margin to the structural MTOW (assuming no obstacle issues, of course)

Kiwiguy
28th Dec 2007, 01:02
At ISA sea level the J.31 needs 1,440 metres at MTOW.

For ISA sea level +20C the J.31 needs 1,650 metres at MTOW.

For ISA 5,000ft altitude +20C the J.31 needs 1,830 metres at MTOW.

Hmm rather take a J.41 thanks, but less humorously I'd still like the real figures and not speculative thanks...:p

Mad (Flt) Scientist
28th Dec 2007, 03:24
What sort of payload will I get from a 3,000m sea level strip ?

Just realised we may be at cross-purposes.
Is this a 3,000m long runway at sea level or a runway of unspecified length at 3000m ASL??

Skystar320
28th Dec 2007, 04:05
Kiwi Guy, thought I have sent you the documents?

I'll resend them via email again, check your inbox

Kiwiguy
28th Dec 2007, 06:51
Hi Skystar320,

I have been away from home for some weeks and up to all sorts of mischief so the short answer is I haven't sifted through the mountain of spam in my inbox lately. Merry Christmas and the happy New Year buzz too...

You will have sent me info for the J32 won't you ?

I also have two J31s I want to operate, independent of what you're helping me with. Anyhow rather than gossip I should naff off and read your email.

Mad Scientist, sorry I am suffering a head cold. My brain is not working properly.

I should have said 1,300 metres length of runway.

Duh .........:D

Is it April first by any chance ?

mad_jock
28th Dec 2007, 08:54
Depends on the aircraft weight. A manual comes in at about 4500kg and an auto pilot comes in at 4750kg.

The fuel burn looks a little low to be honest for 600NM unless your doing long range cruise. I hope you have a toilet fitted :D

What is your alternate fuel ? Hold is 180kg, 30kg for taxi.

Taking a 1000kg of fuel. On a manual which will give you 120kg for Alt fuel (about 30mins radius div fuel)

About 12 males 13 tops. In the winter at below ISA but it will drop off above ISA. But 5-10knots of head wind will easily get you back up to MTOW of 7059kg. But I wouldn't contract for above 10 pax if you get a head wind or its hot your going to struggle with 12.

Also check your drift downs J31 is a bit shite for that at high weights. Havent got the book here but as soon as the MSA gets above 5000 you have problems.

Good news is that ESAS or whatever you call it. Is making all manufactor's put all their data on the web. So no more of this nonsense of refusing to publish MMEL's and performance data online.

Kiwiguy
28th Dec 2007, 22:43
Thanks Mad Jock. Now I've cleared my brain blockage I'm getting some useful info.

I based fuel burn on the only figures available to me which is cost econ cruise 260kts at 20,000ft =606lb/hr.

Let me phrase it differently then ...

Say a mission fuel of 400nm with 30 min hold and 50nm diversion ?
What do you reckon a realistic fuel allowance is for that mission ?

So about 12 pax is realistic from a 3000 metre strip for that fuel weight ?

Would the J.32EP offer any better payload capacity from the same strip on the same route ?

mad_jock
28th Dec 2007, 23:43
Your getting your types confused

Looks like you have the fuel burns/TAS for J41 confused with J31.

The 7000kg for 1440m strip looks about right.


J31 in the cruise TAS is 230knts and burns 260-280/hour which if you go above FL220 TAS will drop back to 210 and the burn down to 220kg/hour

I would say about 750-800kg which would give you 15 males out of your 1300meter strip.

This is all for standard cruise not long range. If you go for long range you will reduce the fuel quite significantly but you would run the risk of pax dieing of old age before you got to the destination.

Just by going for a J32 your going to increase the load by 1 if not 2 pax.

The EDAM option does other things in respect to climb gradients and flap zero departures. It might not make that much difference with a runway restricted departure. If you were having probs with departure profiles it would help. But you will need to check this.

Yes 11-12 is realistic with 50nm diversion. But it is going to be extremely tight and if you get unfavourable wind conditions your stuffed.

But without knowing your aircrafts initial weight I can't really say. Two of our fleet could do it with 12 the others 11 and the autopilot machine 9.

mad_jock
29th Dec 2007, 00:27
PS It really is the wrong aircraft for that length of route.

The punters will hate being stuck in it for 2 hours plus.

300 miles should really be the max you plan for if you want any repeat buisness.

Kiwiguy
29th Dec 2007, 01:37
Hmmm ... well thanks. Some helpful stuff there.

Umm well the figures came from a directory published in Flight International dated 7 May 1988 for commuter aircraft.

That gave the cost econ cruise at 260 knots as 606 lb/hr

LR cruise at 235 kt was given as 486 lb/hr (220kg/hr) which is how you've quoted it.

Okay so provided the OEW isn't too high then it gives me 12 pax from a 1,300m runway /

Anyone who can better that with actual take off weight from 1,300m is most appreciated.

The alternative to this >2 hour flight is to hub through another airport and take 3.5-4 hours


Good news is that ESAS or whatever you call it. Is making all manufactor's put all their data on the web. So no more of this nonsense of refusing to publish MMEL's and performance data online.


Re the obligatory publishing of figures any idea where the online reference for a J.31 take off distance is please ?

mad_jock
29th Dec 2007, 11:14
It isn't in force yet and they haven't done it.

Your going to be 3 hours anyway for the sector zero wind.

These 25 year old age aircraft are noisy- cold in the winter / roasting in the summer. Door seal sqealing like a bitch. Chemi bog that only holds 8 pints without flooding and running down the cabin or it runs down the inside and emptys all over the bags in the pod. This why they are so cheap. But you really can't beat them for up to an hour sector. Pilots love flying them :ok: well some do, well I do. Pax mostly love them because they can see the cockpit and can see out the front landing. Its just as soon as you go above 1.5 hour sector it stops being fun/ something you can deal with and turns into an ordeal of noise, vibration for a pricely sum

The aircraft are all getting very tired, lots of silly snags which are age related eg wires becoming brittle, fuel indication problems which are a right pain to fix. If you do use them make sure they are in the hanger every night they don't like sitting outside in the rain/snow.

Maybe I have just spent to much time in them but given the choice I would go via the hub instead of sitting in a J31 for 3 hours. Even given topless hostie, free food/drink and being let up the front to fly it when i really lost the will to exsist.

The J41 would be alot better option

Give BAe there due they might not publish the data but they are quite helpful if your thinking about operating them.

http://www.baesystems.com/WorldwideLocations/UnitedKingdom/Locations/Prestwick/autoGen_107115153719.html.

And if you do get it sorted and need crew I certainly wouldn't mind coming down for a year to get it off the ground.

Kiwiguy
30th Dec 2007, 02:07
If you do use them make sure they are in the hanger every night they don't like sitting outside in the rain/snow.


Thanks Mad Jock. Snow isn't much of an issue around the parts of NZ where I would fly them, but rain can be.

I used Skystar320's graphs (from BAe) and they suggest MTOW from a 5,200ft runway for 400nm (+IFR res) is 15,000lb

I used the data to construct a graph for the runway I am contemplating and the MTOW there is 14,675lb which renders 14.5 pax (ie 86kg pax plus 20kg baggage)

I don't agree that the time will go over 2 hours, but the alternative is worse and more expensive for punters. I had a longish trip in a B1900D recently and that was cool for me.

Re coming to work here, roger that and I'll stay in touch. You'd like Kiwi land.

halas
30th Dec 2007, 12:54
Been ten years since l operated them, but as it's a transport cat. aeroplane you will have to factor in obstacle clearance etc. So it depends on a lot more info than just runway length, but geography and performance as well.

Skywest had water-meth :ugh: and the 3 degree offset of the tail to account for critical engine failure on dirt strips :yuk:

And no l didn't enjoy flying them. Got RSI from hitting that damn bus-tie re-set switch.

halas

Kiwiguy
30th Dec 2007, 23:31
Obstacle clearance is a non issue at this departure airport.

Sealed runway, elevated above surrounding terrain.

Sudjes
12th May 2010, 20:48
Hey Kiwiguy,

I know this is an old post but it doesn't cost me anything to try and see if you can still help me. I'm looking for the performance data of the J31 for runway design/ airport planning. Do you for any chance still have the J31 performance sheets?? Because the
links for the 31 don't work anymore. only J41 available on the website.
It would be great help for me.
Greetz,

Masud

Tmbstory
13th May 2010, 17:14
Kiwiguy:

I have a Jetstream 31 Pilot Engineering Manual, which has heaps of information in it.

Let me know what specific information you want and if I can help, I will do so.

Tmb

J31 MAN
24th May 2010, 14:32
Ring the performance data section at BAE Prestwick. Really helpful team.

PIK3141
24th May 2010, 19:23
e-mail rafltops@<hidden> with the serial number of your aeroplane and your specific request if you wish.