JSF and A400M at risk?

[Modern Elmo]

What do "very small" and "significant" mean? In VL mode the main engine on the F-35B is producing some 15,700 pounds of thrust, while a Harrier's aft nozzles deliver about 12,000 pounds of thrust. (The fore-aft split is roughly equal.)

Lockheed claims a bigger number for vertical thrust (which should be larger than maximum dry thrust in level flight -- that's the benefit of the lift fan):

Hover–Pit Ground Tests Validate Propulsion System and Aircraft Response

FORT WORTH, Texas, April 23rd, 2009 --


The first F-35B short takeoff/vertical landing stealth fighter operates in vertical-landing mode on a special "hover pit" at Lockheed Martin in Fort Worth, Texas, during an April test.

...

The F-35B Lightning II short takeoff/vertical landing (STOVL) variant has demonstrated during testing that it produces excess vertical thrust – more than required to carry out its missions. The tests, conducted on a specially instrumented “hover pit,” also validated the performance of aircraft software, controls, thermal management, STOVL-system hardware and other systems.

“The performance level measured was absolutely exceptional,” said J.D. McFarlan, Lockheed Martin F-35 Air Vehicle lead. “We demonstrated 41,100 pounds of vertical thrust against our requirement of 40,550 pounds.This means we will deliver excellent margin for the vertical landing and short takeoff performance we’ve committed to our STOVL customers,” ...

http://www.lockheedmartin.com/news/press_releases/2009/090423ae_f-35-hover-pit-ground-tests.html



But the F135's overall pressure ratio is almost twice as high, which would point to a much higher jet velocity (which LockMart doesn't mention), the JSF nozzle is much closer to the ground, and the Harrier has two nozzles, several feet apart.

You need to clarify "overall pressure ratio." The lift fan's output is much cooler and at lower dynamic pressure than the exhaust from the aft nozzle. Yes. the F135 engine has a much larger expansion ratio than older engines such as the Harrier's.

Indeed, when the CONOPS starts to involve 3000-foot strips, 800-foot, 50000-ton ships and SRVLs, and your primary mission is CAS


Don't agree that the F-35B will be CAS only. See for example Table 2 above:

"Day 95 Withstand attacks by low-flying aircraft and missiles."