Page 55 - HeliOps Frontline Issue 26

HELIOPS FRONTLINE / ISSUE 26 / 2019 55

Intriguingly, the US Army has also been funding a demonstration
program that replaces the standard Honeywell T55-714A engines on
the CH-47D/F with a pair of General Electric T408 engines, normally
to be found (as a threesome) powering the Sikorsky CH-53K King
Stallion heavy lift helicopter. Despite a troubled development
program, and being significantly late for its prime customer,
the US Marine Corps, the King Stallion has immense potential,
comfortably outlifting the CH-47F in pure payload terms and
competing actively against the CH-47F in the German and Israeli
heavy lift competitions. Whilst the T55-714A produces circa 5000hp
per engine, the T408 outputs some 2500hp more per engine. An
immediate 30+% increase in engine power could, with appropriate
drivetrain, transmission and rotor system upgrades, propel the CH-
47 to near payload equivalence with the CH-53K at a significantly
reduced cost; and Boeing claim that the T408 would also provide
an approximate 15% fuel saving over the T55. The rationale behind
the Army’s funding for the T408 experiment is not clear; however
an up-engined Chinook may prove a frightening ‘stalking horse’ for
Sikorsky, who have already suffered the embarrassment of seeing
the Senate Armed Service Committee publicly order the Marines
to request a briefing on CH-47 capabilities as, at least a partial,
amelioration of the delays and cost overruns afflicting the King
Stallion program.
More prosaically, perhaps the US Army has decided to only kick
the Heavy Lift can a few years down the road, not the 20 or so years
that would be required to design, develop, test and field some form
of JMR-H. If a ‘Block 1.5’ CH-47F provides a useful short term uplift
in performance, the Army could invest in the fleet wide upgrade
while paying Boeing to study what a ‘CH-47H’ might look like with
the rest of the Block II modifications and a new drivetrain able
to fully utilise the enhanced power and reduced operating costs
promised by the T408 engines.
Sadly then, the QTR seems further away than ever. Heavy lift
assets will stay stuck at 170-180kts for the foreseeable future.
Perhaps the successful delivery of FLRAA and FARA may yet
embolden the US Army to take the next step up the capability
ladder, but, until they do, a combination of ‘Block 1.5’ CH-47F and
“CH-47H” may just be the correct and pragmatic approach. n