HS-125 Pilots: spoilers+flaps??

digduggy

digduggy

Well-Known Member
I've been flying this thing for two years now and am still wondering why you can't... Not interested in doing it, but intrigued why the limitation...
 
digduggy said:
I've been flying this thing for two years now and am still wondering why you can't... Not interested in doing it, but intrigued why the limitation...
Click to expand...
Large shift in center of lift or possible large separation of laminar flow?
 
I seem to remember that it has something to do with the air coming over the spoiler and how it then hits the flap (I'm guessing not in a good way). But it's been a while since I've flown one, so that could be wrong.
 
The flaps are not designed to take the buffeting that will come off the spoilers... This can cause damage within the flap drives and the flaps themselves.
 
Same limitation in the Lears, likely for the same reasons. When I was flying the Falcon you could do do flaps + spoilers, but it may be that in addition to the aerodynamics working working there, that the boosted flight controls are the difference.
 
Patrick said:
Same limitation in the Lears, likely for the same reasons. When I was flying the Falcon you could do do flaps + spoilers, but it may be that in addition to the aerodynamics working working there, that the boosted flight controls are the difference.
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Yes, that is the reason the Lears have the limitation. Never flown a Hawker but it wouldn't surprise me if it's the same.
 
auw2fly said:
I seem to remember that it has something to do with the air coming over the spoiler and how it then hits the flap (I'm guessing not in a good way). But it's been a while since I've flown one, so that could be wrong.
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That's what you know who told me. But he also said, and demonstrated, that as far as controllability goes, nothing bad happens at all.
 
digduggy said:
I've been flying this thing for two years now and am still wondering why you can't... Not interested in doing it, but intrigued why the limitation...
Click to expand...

I'd be willing to bet it's something along the lines of why you still can't pull engine bleed air for pressurization on takeoff or landing.

Sometime, way back in the day, I'm betting an early model HS125 was damaged, and the limitation went into place.

And let's talk about gear pins. Story I was told was that they started using them because some numbnuts mechanic towed one around a corner doing about 25 mph and side loaded the gear. Tow it normally and there isn't any reason to have them.
 
Every "upgrade" that's ever been done to a HS-125 has been done as a "factory mod". While we were taking delivery of our 850XP, a customer asked for a binder with a list of all factory mods. They filled a 6" binder.

Major changes to the systems and associated limitations would require a new Type Certificate, costing many dollars in flight testing and certification. As we know, Hawker-Siddley/Raytheon/Hawker-Beechcraft was never good at that.
 
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