Fuel saving techniques Hawker800XP
Join Date: Jan 2000
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On the Bus you go down when the box says so.. remembering of course crap in leads to embarassment, high speed (in an effort to get the height off) and a go around burning more fuel because you forgot that she is reluctant to slow down! Go down slow down she wont do!
For fuel calcs/saving, actual (at your level) TAT/SAT in the computer makes a massive difference and if blessed with auto thrust then in cruise go to manual as once set power will be constant thus saving fuel over A/T (A/T constantly changes thrust to maintain managed/selected speed)
For fuel calcs/saving, actual (at your level) TAT/SAT in the computer makes a massive difference and if blessed with auto thrust then in cruise go to manual as once set power will be constant thus saving fuel over A/T (A/T constantly changes thrust to maintain managed/selected speed)
Join Date: Feb 2006
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250 into .70 then LRC by the book got us 6hrs 40 with 1300 pounds on arrival in an 800xp (honeywell). Just picked up a 900xp and getting the unable crz , now i know how to fix it thanks . We have decided that it is cheaper to fly max cruise , less time on the MR , less MSP, Less maitenance and at resale less hrs .We have also found that climbing at 280 into .74 at isa +10 and high t/o weight we are getting better climb rates in the high 30,s upto 410 then we accelerate much quicker . We only have 40 hrs on the 900 but so far this seems to work .I am open to other suggestions . Just for the record it performs much better than the 800 ,and better than book figures in cruise . Sounds a bit like a salesman but im not .
Join Date: Jun 2004
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As someone attested to in a previous post, be careful about leaving fuel in the Ventral Tank too long. I just double checked my 900XP AFM and it's not an option for us. It states we "shall" transfer fuel from the ventral to the wings when each wing has 3300#s. In the case of fuel not transfering from the ventral, well you can continue the flight so as to land not more than 22,500#s. Seeing that the average weight of a 900XP is around 16,500, that doesn't give you a lot of time to get on the ground.
Be careful.
Does anyone turn both MAV's to LP ON at high altitude and longe range. I have heard about this in the older hawkers but haven't wrapped my head around the systems yet....
Be careful.
Does anyone turn both MAV's to LP ON at high altitude and longe range. I have heard about this in the older hawkers but haven't wrapped my head around the systems yet....
Join Date: Jul 2004
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Main Air Valves
Yes, the good old Viper engines...
The vipers were simply not strong enough to handle the bleeds at all times.
One of the historic remains of the Viper era is the step in the descent checklist: "main air valves - on".
On the Honeywells there are 2 ports to feed the pressure system, a high and a low pressure port. Normally the LP port is sufficient to feed the system, but at low RPM the HP port might be needed, if the LP pressure is not high enough. With the main air valve switch in the "ON" position the switchover from LP to HP is handeled automatically. With the switch position "LP" the system is forced to stay on the LP port.
The Honeywells will put out enough power and pressure in cruise, so the bleed system will stay all the times anyway on the LP port, unless you reduce power for the descent. Switching it to "LP" does not improve efficiency.
The vipers were simply not strong enough to handle the bleeds at all times.
One of the historic remains of the Viper era is the step in the descent checklist: "main air valves - on".
On the Honeywells there are 2 ports to feed the pressure system, a high and a low pressure port. Normally the LP port is sufficient to feed the system, but at low RPM the HP port might be needed, if the LP pressure is not high enough. With the main air valve switch in the "ON" position the switchover from LP to HP is handeled automatically. With the switch position "LP" the system is forced to stay on the LP port.
The Honeywells will put out enough power and pressure in cruise, so the bleed system will stay all the times anyway on the LP port, unless you reduce power for the descent. Switching it to "LP" does not improve efficiency.
Join Date: Jan 2007
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Why would fuel not tranfer? I have never heard this ever being a remote possibility on the 800 series as the cock is mechanically conected and the transfer is via jet pump. Is it different on the 900? As long as the C og G stays in the envelope I see no problem.
Another question? On the 750 series the long range fuel tank is substituted for a baggage bay. Do you have to transfer the bags to the cabin when the fuel gets to 3300 lbs in each wing. Could be quite a tricky operation for the co-pilot!!
Another question? On the 750 series the long range fuel tank is substituted for a baggage bay. Do you have to transfer the bags to the cabin when the fuel gets to 3300 lbs in each wing. Could be quite a tricky operation for the co-pilot!!
Join Date: Nov 2002
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The ventral on an 800xp holds 1650lb of fuel as I remember and is either full or empty. Pax baggage is not normally that heavy. Fuel is transferred by jetpumps powered by the wing fuel pumps. The ventral tank lever could be stuck due to cabling, valves etc. A blockage or airlock could also trap the fuel. It's best to transfer at 3300lb a side or whatever the good book says. It's not worth delaying it or you could enter test pilot terretory.
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no ventral
H750,
to answer your question:
The copilot only has to transfer the bags when you have filled the EBC with 1500lbs of luggage. (which is of course not allowed)
N.
to answer your question:
The copilot only has to transfer the bags when you have filled the EBC with 1500lbs of luggage. (which is of course not allowed)
N.
Join Date: Jan 2007
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No Ventral
The next question for you 850/750 experts.
On the 800/850 the weight of the fuel in the long range tank is not a zero fuel weight item. I.E. you load up the cabin up to your max ZFW then load max wing fuel and then load full fuel in the long range tank. (subject to Max gross)
On the 750 does the baggage weight in the external baggage bay get added into the zero fuel weight or is it added in afterwards as in the 800/850?
I suspect that the weight in the extenal baggage bay gets included in the ZFW. If that is the case how does the airplane know whether it's fuel or baggage down the back?
Perhaps somebody who has done the 750 course could answer.
On the 800/850 the weight of the fuel in the long range tank is not a zero fuel weight item. I.E. you load up the cabin up to your max ZFW then load max wing fuel and then load full fuel in the long range tank. (subject to Max gross)
On the 750 does the baggage weight in the external baggage bay get added into the zero fuel weight or is it added in afterwards as in the 800/850?
I suspect that the weight in the extenal baggage bay gets included in the ZFW. If that is the case how does the airplane know whether it's fuel or baggage down the back?
Perhaps somebody who has done the 750 course could answer.
Join Date: Nov 2002
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Sorry H750, i've not done a 750 course but have flown an -800 without ventral a few times.
The ventral fuel tank is supposed to be empty on landing, so the vental fuel is not included in the stress calc's for landing. You are limited to 280kt with ventral fuel. I'm not sure why but it could be to do with reducing wing bending moments for the design upgust calc's.
On a LJ35 which has a fuselage tank. You can land with fuel in it but there is a Max Wing Bending Wt which is the include ZFW + Fus tank fuel.
(By the way, I was told that if you had to land immediately after T/O with full fuel, you could jettison the ventral fuel by using AUX TFR. it would come out of the wing tips. This is not in the manual. I would only do this if the RW was too short for an immediate overweight landing.)
The ventral fuel tank is supposed to be empty on landing, so the vental fuel is not included in the stress calc's for landing. You are limited to 280kt with ventral fuel. I'm not sure why but it could be to do with reducing wing bending moments for the design upgust calc's.
On a LJ35 which has a fuselage tank. You can land with fuel in it but there is a Max Wing Bending Wt which is the include ZFW + Fus tank fuel.
(By the way, I was told that if you had to land immediately after T/O with full fuel, you could jettison the ventral fuel by using AUX TFR. it would come out of the wing tips. This is not in the manual. I would only do this if the RW was too short for an immediate overweight landing.)
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I believe that the reason the ventral tank has to be full or empty for take off or landing is due to the fact that it has no internal baffling, unlike the wing tanks which are divided into sections. The possible outcome was demonstrated a few years back when a certain sea ferry set off with its bow doors open and subsequently rolled over when the water it ingested started sloshing around inside.
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A question for the Hawker experts here: based on your experience, what is the best method for loading passenger baggage? Which method do you use? Anything other than these?
1) let pax bring their own bag onboard and self-stow
2) have other pilot grab bags and load prior to boarding
3) have pax bring bags to airstair, and pilot loads after pax boarding
Any info appreciated.
1) let pax bring their own bag onboard and self-stow
2) have other pilot grab bags and load prior to boarding
3) have pax bring bags to airstair, and pilot loads after pax boarding
Any info appreciated.
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"Unable cruise Alt"
Guys, You dont need to fiddle the the defaults page to get rid of this. It is there to tell you that with the ISA you have put in, at the weight you have put in, that the aeroplane cannot make that Alt. Use it like it was designed, update the ISA on the perf init page as you climb, to see what the optimum altitude is for that weight. I use it on every flight, it works great.
Another tip, which very few people seem to use. Make sure all your defaults are correct, PM me if you cant find them, Set your vert and lateral nav for take off as Hdg - VPitch, after gear up, hit FLC go to the FMS hit PERF x 2 (perf menu) and hit resume. This will give you your climb all the way to cruise, and will honor any altitude restrictions on sids or airspace. Very important to ensure that the vnav defaults are correct.
Another tip, which very few people seem to use. Make sure all your defaults are correct, PM me if you cant find them, Set your vert and lateral nav for take off as Hdg - VPitch, after gear up, hit FLC go to the FMS hit PERF x 2 (perf menu) and hit resume. This will give you your climb all the way to cruise, and will honor any altitude restrictions on sids or airspace. Very important to ensure that the vnav defaults are correct.
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Hawker 750....
Surely you are joking right ??
Q..When DO YOU HAVE TO transfer fuel from ventral to mains ?
A.. at 3300lbs. ONLY at 3300lbs, not before, or after.
Please re-read your AFM, mate
Surely you are joking right ??
Q..When DO YOU HAVE TO transfer fuel from ventral to mains ?
A.. at 3300lbs. ONLY at 3300lbs, not before, or after.
Please re-read your AFM, mate
