Predator question

[avatar]

Okay
Gentlemen,

can anyone tell me why the Predator B (Reaper) has it's tail up while its smaller predecessor is tail down?

 

[AeroFranz]

Good question. I can only offer more or less plausible causes:
Predator B was designed from the outset to carry weapons, as such the large inverted-V tails might have gotten in the way of the exhaust of powered munitions. Or maybe the structural integration of the turboprop engine worked best with the V-layout, but I doubt. Either way, flight qualities are probably the same provided the vertical and horizontal projected areas are the same. there might be a trade in spiral stability vs dutch roll, but i doubt you would really care, with an autopilot taking care of things.
It is interesting to note that the earlier GA Prowler had the opposite arrangement (inverted Y?)
Any other ideas?

 

[Just call me Ray]

The reason why the Predator B (Reaper) has its rear control surfaces the way they are is simple - that way, the enlarged control surfaces compared to the MQ-1 will have less of a chance of being struck upon rotation without the need for longer landing gear or folding surfaces.

Why the MQ-1 isn't like that then, I have no idea. Maybe General Atomics just felt like being different.

 

[AeroFranz]

Predator A's ancestry includes the Teal tube launched cruise missile (I believe that was the name), whose wing had a fuselage mounted pivot. The wing would swivel and stow longitudinally on top of the fuselage. That precluded the installation of an 'upright' tail. My guess is, Abe Karem's attitude must have been to save development money and keep things the way they were for the successive vehicles (engineers are a lazy bunch...i should know!)

I was searching the forum for Teal references and found none. the development of that family of vehicles is varied and fascinating. Maybe I should start a thread on this...

 

[AeroFranz]

hmph...I guess i should check my references before quoting by memory. The program name was TEAL RAIN, and the vehicle's name was Amber. Abe Karem's Leading systems of Irvine, CA, designed it, went bankrupt, ad now GA is selling those things faster than they can make'em.

here you can find a decent picture of Amber, with the pylon mounted wing clearly visible.
http://spyflight.co.uk/Predator.htm
for more info:
http://en.wikipedia.org/wiki/The_prehistory_of_endurance_UAVs

The inverted allowed a longer wing to fold above the fuselage, and as mentioned before had the nice synergistic effect of protecting the prop.

 

[avatar]

hey thanks for the replies.

it seems that the distance between the tail surfaces in the case of the Reaper is greater than that in the case of the predator.

 

[LowObservable]

The moment arm on the Reaper is relatively shorter. An inverted V-tail would be too large for ground clearance.

 

[Mithrandir]

notice the "B" (Reaper) has control surfaces and the "A" has full flying tails...

The tails on the AMBER were also full flying and would fold back as well as the prop folding back and the outer wing panels would fold under the main panel and it would pivot on the pylon so it could be stowed nearly assembled in a small container.... also this was the configuration for the Rocket Launched "Option One" as it was called within LSI.

 

[AeroFranz]

Thanks!
I've been looking for info on the folding on Amber for quite a while. Do you have any pictures by any chance?