Hawker flap settings ?

[tathepilot]

I've noticed on the Hawker jet (during roll-out) that the flaps seem to be almost 90 degrees. Is that the norm on all HS's ? I'm not sure which model I saw land today.

Aprox when is that final flap setting put in?
Is there a drastic speed reduction when the final flaps are selected?


thx

 

[T-Gates]

Even though I've never flown a Hawker, I'm gonna open my mouth at risk of sounding like an idiot.

I believe that they perform a lift dumping/speed brake function after the plane has landed, I don't think that they are deployed on final. I could be wrong however.

 

[Jeff Helgeson]

Lift-dump mechanism!

It is the "lift-dump" mechanism. Most Hawkers don't have reversers and use the lift-dump. There is a handle to the left of the throttles with a balk mechanism, lift up and pull back and you go from full flaps to 90 degrees of lift dump.

Some of the middle aged HS-125s had the option for reverses, but the weight and performance penalties made them obsolete and many operators had them removed after paying over half a million to have them installed.

Later models now have them and they work fines.

Jeff

 

[tathepilot]

Around how many degrees is the final flap setting prior to lift dump ?

 

[Jeff Helgeson]

40 0r 45 degrees

I thought you might ask that! I will go with "B" 45 degrees. I believe that is correct. So the angle doubles. It feels like dropping anker!

Jeff

 

[capt_zman]

45 degrees is correct. Lift dump extends to 75 degrees.


Z-

 

[speedwings]

Nope

The Hawker goes from landing flap position (45 degrees) to 75 degrees REALLY fast when you select lift dump. You initially get both upper and lower air brakes but when weight on wheels, you lift the handle up and down further. In less than 2 seconds and they're all out there; both flaps at 75 degrees and upper and lower airbrake. It's very effective.

Older Hawkers (400-most 700's) do not have TR's. The TR's were installed as a mod by Aeronca and were electro-pneumatic. They were much more trouble then they were worth. Aside from not working half the time and causing tons of maintenance problems, there was a substantial (350lbs) weight increase and a reduction in power. Those TR's essentially made our 8 PAX Hawker 700 a 7 PAX airplane due to max zero fuel weight limitation. By the time the TR's fully extended and were available for an increase in power, you were almost below TR effective speed.

Now starting with the 800 and 800XP models, BAE & Raytheon changed the TR's to the traditional clam shell doors that weren't such a maintenance & performance hog. They are light, effective and quick to deploy. It's a pretty good system. I hope that clears things up.

SW

 

[speedwings]

I forgot, to answer your other questions, the flap settings are 15, 25, and 45 (75 on ground only in lift dump).

You transition from 25 to 45 degrees of flaps around 1000' agl on a visual and at the FAF on an approach just like any other jet. It is a substantial increase in power - from 63% to around 75% N1 is required during descent on a 3 degree GS. Speeds will drop around 30 knots in 10 seconds if you don't increase power as they are extending from 25 to 45 degrees.

Cheers!

 

[tathepilot]

I love this board !

 

[FracCapt]

We seem to get asked that question fairly often....."Dang, how far do your flaps go down?" 45 degrees is max in flight, 75 degrees in lift dump on the ground. When you select lift dump, and you have weight on wheels, the airbrakes(upper and lower) also go far beyond their inflight max travel - though I don't recall the specific degrees. I just know that everytime I land, it works extremely well. TR's are a waste on a Hawker except on contaminated runways. Using reverse on a dry runway might allow you to stop 100' earlier than without(assuming you use max braking in both scenarios). When you touch down and deploy the lift dump, the airplane slows down so fast you don't have time for the engines to spool up in reverse before you have to take them back down to idle reverse.