posted on Dec, 20 2017 @ 02:14 PM
originally posted by: penroc3
a reply to: mightmight
It probably has some crazy vortexes and needs the odd configuration to made drogue refueling feasible as well as masking the IR signature output of
Tail configuration is probably signature driven. Also less interference drag which makes sense because of the endurance/efficiency requirements. Doubt
vortices enter into it.
Massive tail-something-wings stand out.
They are big because to be effective a rule of thumb is that a butterfly tail needs to have roughly the same area as a the tail and tailplanes in a
standard tail arrangement. Look how massive the F-23 tails look, for example. They are also probably even larger than most because the CG in this
platform is well to the aft.
CBARS is looking to be around 60,000 lb GW. When the shift happened to refueling focus and away from signature, it meant it was going to need a tail.
Look at the X-47B. Assuming a similar planform for the NG proposal scaled up to 60,000 lbs or so and operating heavy frequently primarily as a tanker.
Where is the CG for the flying wing? Way aft. Now the moment arm is MUCH shorter. Means you need more force to control pitch. Which means more area
than is easily arranged on a flying wing. Starts cutting into your internal volume for wet wings and/or sensor deployment. So you need a tail. So that
and the signature requirements being relaxed is probably why NG said, "You can't make up your minds. We're done".
Judging by the apparent location of the landing gear, I'd say the Boeing design has a CG toward the rear also. Not as far aft as the flying wing, but
aftward. So it needs larger surfaces due to the shorter moment arm.
Compare that to the Avenger design from GA. Where's that CG? And the tail surfaces are a greater distance aft, so needs less area (but they're still
pretty big. Just higher aspect ratio and smaller in comparison to the butterfly tail on Boeing's bird).
Well according to GA they are very happy with the revised requirements and delighted to optimize their entry accordingly.
The shift to tanking and away from penetrating strike is a huge plus for the more conventional designs as GA is rumoured to have and Boeing seems to
be putting forward. So small wonder they are thrilled.