Landing Flaps

[jackieman271 2]

In normal operations, does the 850XP use flaps 25 or 45 for landing? The GPWS activates at flaps 45.

Also, I've seen videos of 800's landing, and they appear to have ground flaps. How are these used? Are they implemented w/ the spoilers?

Thanks

~John M

[JRBarrett 3,048]

In normal operations, does the 850XP use flaps 25 or 45 for landing? The GPWS activates at flaps 45.

Also, I've seen videos of 800's landing, and they appear to have ground flaps. How are these used? Are they implemented w/ the spoilers?

Thanks

~John M

This is the "lift dump" system.

 

Normal landings are made at flaps 45. There is an air brake handle to the left of the power levers. In flight, this acts as a typical speed brake - as the handle is pulled back, the spoilers on the upper wing deploy in relation to the position of the airbrake lever. During flight, this lever cannot be pulled all the way back to the lift dump position due to a mechanical lock-out.

 

On landing, once weight-on-wheels is detected, and assuming that the flaps are at 45 degrees, the interlock in the airbrake handle releases. The pilot pulls the handle back to the normal in-flight detent, lifts up about 1/2 inch, and pulls the handle an addition 5 or 6 inches back to the lift dump position. Doing so causes 3 things to happen: the spoilers on the upper wing rise up to maximum deployment angle, an additional set of spoilers on the bottom of the wing drop down, and the main flaps drive very rapidly from 45 degrees to about 85 degrees, which makes them almost vertical - they stop producing lift and instead produce pure drag.

 

The lift dump, in conjunction with the thrust reversers and wheel brakes give the Hawker a lot of stopping power.

 

The Hawker has a lot of interesting features. The flaps, for instance, are purely hydromechanical. In other words, as long as hydraulic pressure is available, the flaps can be extended and retracted even if there is no electrical power online whatsoever. The pressurization system also has no electrical components. As long as bleed air is available, the cabin pressure can be fully controlled in flight.

 

Likewise the wheel brake anti-skid system is purely mechanical, using devices known as Maxarets located in each wheel hub. These are capable of detecting a wheel skid and applying/releasing brakes as required using an ingenious fluid clutch - again, solely independent of the need for any electrical power, anti-skid computers or wiring.

 

This design philosophy probably harkens back to the days when British aircraft (and automobiles for that matter) were notorious for having unreliable electrical systems!

[jackieman271 2]

This is the "lift dump" system.

Wow, thanks so much for the information! It appears Carenado failed to model the Lift Dump system. When you land at flaps 45, and then activate the Lift Dump system, the flaps appear to stay at the same angle; but the spoilers do appear do extend a little bit more.

It's a pretty interesting airplane! 40+ year design crafted to compete with today's standards.

 

Thanks again!

Edited April 25, 2015 by n4gix
Bad enough to do a complete quote, but to do it twice? Good grief.

[autogyro 18]

Not sure if it makes a difference, but the lift dump airbrakes should only be used after all wheels have weight (I.E. After noise wheel touchdown).

[JRBarrett 3,048]

Wow, thanks so much for the information! It appears Carenado failed to model the Lift Dump system. When you land at flaps 45, and then activate the Lift Dump system, the flaps appear to stay at the same angle; but the spoilers do appear do extend a little bit more.

It's a pretty interesting airplane! 40+ year design crafted to compete with today's standards.

 

Thanks again!

You're welcome! As a mechanic, I really like working on Hawkers, - (some mechanics hate them.) The airframe is extremely rugged in design - very solid construction. The cabin has a lot more headroom than many other biz jets of similar size class, which makes it a favorite of passengers. The main entrance door is of a very simple and reliable design, easy to open and close when compared to the split clamshell doors on most Lear Jets. One big drawback of the 800 series though is very limited storage space for passenger baggage. Everything has to be stored in the cabin - there is no dedicated baggage compartment at all - except for the large Hawker 1000, but they only ever built 54 of those.

 

Since I know the airplane well, I'll probably buy the Carenado version eventually, but probably not until they work some of the bugs out.

[ryanbatc 12,814]

Thanks for your technical insight Jim!  Very cool.  A local pilot flies an older Hawker here in Duluth, for the Duluth area power company (MN Power / Allete) N141AL - they gave a few of us controllers a tour of the aircraft, mx hangar, facilities last year.  Pretty cramped little jet.  And the panel is just "slightly" older than this Carenado variant hehe.

 

(poor pic quality sorry only had my phone and the lighting was dim)

 

[JRBarrett 3,048]

Yeah, that's a "classic" Hawker cockpit. The GNS-XLS FMSs were definitely an add-on at some point.

 

So, I did buy the Carenado Hawker. Just going through some preliminary tests. Surprisingly, the lift dump system IS fully modeled. With flaps 45 and engines running, if you grab the airbrake lever in the VC with the mouse cursor, you can pull it down to the max flight detent, then pull it up and pull it the rest of the way down, and by George, the flaps do drive to 85 degrees in 3 seconds. They even have the "zing" sound that the flap hydraulic motor makes when it shifts to high speed mode,

 

One big electrical mistake is that they have the engine generators linked to the ALTERNATOR switches. That is incorrect. The alternators are only used to provide 3-phase 115 volt current for the electrically-heated front and side cockpit windows.

 

Generator switches appear to do nothing, ditto for the inverter switches. Ditto for the main air valve switches, which control engine bleed air. Bleed air appears to be present as soon as engines are running, no matter where the switches are set.

 

The PFD is set to ARC mode all the time, the menu option to select ROSE mode is present when the PFD "FORMAT" key is pressed, but selecting ROSE does nothing. On the other hand, the options to select NAV source between FMS/VOR1/VOR2 works right, as do the bearing pointer selections.

 

Struggled up to FL280 with only 2 pilots and only 6000 pounds total fuel in the wings, and must say that the aircraft is woefully underpowered. I have the engines firewalled at 98 percent, and am barely maintaining mach .70 with a fuel flow rate of 3500 lbs/hr per engine, which is about 2500 lbs/hr (per engine) too high for that speed. At max power setting in level flight at 28000 feet, a Hawker would overspeed easily. If I tried to take off with full wing and ventral fuel, and 2 or 3 passengers, I have my doubts that it would even get airborne. Engine thrust needs major work.

 

Lateral nav modes work really well - both heading select and FMS NAV tracking are excellent. Vertical modes are whacked. Still trying to figure out what the heck Carenado is trying to do here!

 

Frame rate quite good, and though VAS consumption on the ground seemed rather high, it reduced substantially once I took off.

 

Going to bed now, but will explore more tomorrow.

 

Also, the APU start-up sequence is very well-modeled, but once it's running, generator control,switch and bleed air switch appear to have no effect - i.e. gen is always on, as is bleed air.

[ryanbatc 12,814]

Hmmm I've found the flight model decent compared to cruise figures. What are you checking CLB performace against? Your rw knowledge or charts? How do I read the CLB charts? What is 160kias/250kias? Are those best rate and cruise CLB profiles?

[JRBarrett 3,048]

Hmmm I've found the flight model decent compared to cruise figures. What are you checking CLB performace against? Your rw knowledge or charts? How do I read the CLB charts? What is 160kias/250kias? Are those best rate and cruise CLB profiles?

R/W experience re: cruise speed vs. thrust setting and fuel flow. I'm not a Hawker pilot, but as a Mx/avionics tech have spent many hours in the jump seat on long flights, and am quite sure that the Carenado model requires way too much power and fuel flow - at least at 28,000 feet. Lower down, (below 10,000) N1 vs. airspeed vs. FF is quite a bit better.

 

I haven't looked at the included charts yet, but will do so tonight. I am at work today.

 

My initial test flights have been done with no external weather injection, and temps at the various altitudes have been right at the standard ISA values.

[JGreen5278 21]

Hmmm I've found the flight model decent compared to cruise figures. What are you checking CLB performace against? Your rw knowledge or charts? How do I read the CLB charts? What is 160kias/250kias? Are those best rate and cruise CLB profiles?

Hello gents, that was actually my next question how close is she from your findings to the provided performance data? I think I may bite on this one even if she is somewhere near the ballpark despite her issues.

Disregard, answered my question. 

[jackieman271 2]

Yeah, that's a "classic" Hawker cockpit. The GNS-XLS FMSs were definitely an add-on at some point.

Yeah, I realized that the lift dump system is modeled right after I posted that.

The Hawker is a very interesting aircraft. Good speed, good range, and good stopping performance. An ideal business jet!

Thanks again!

Edited April 25, 2015 by n4gix
Please stop quoting the entire post! You do have a delete key, yes?