New LLTV Needed?

From "First Man", Neil Armstrong said, "The helicopter wasn't a good
simulation of the lunar module control at all...Had it been we would
have configured a helicopter such that it could duplicate lunar
flying...The natural requirements of helicopter aerodynamics preclude
you from duplicating the lunar module characteristics. Nevertheless,
the helicopter was valuable to understand the trajectories and visual
fields and rates. You could duplicate the flight paths that you
wanted." The general consensus among the other Apollo astronauts quoted
in the book seemed to be that a helicopter was a poor training aid for
landing the LM on the moon.
Bill Anders said, "The guys who flew more intuitively or who relied
too much on their helicopter experience would have tumbled into craters
or landed on rocks if they tried to land on the moon." It seems to me
that if any arguement can be made for having a reality based lunar
landing training vehicle, then maybe a Harrier/Directed Thrust type
machine would be the way to go.
A fly by wire helicopter, I suspect, can probably be made to
replicate a Lander's qualities to a certain extent but can any
control system effectively eliminate the aerodynamic byproducts
inherent in helicopter flight that make it a poor moon landing trainer
(ie. rotor downwash, torques, inertia in Earth gravity, etc.)?
I'm not an engineer, so I don't really know what might be feasibly
accomplished today with FBW, versus what Leonov and the Apollo astros
had to work with. But I'd like to hear more thoughts.
Thanks

In article ,
says...
Given the abilities of today's flight simulators, it's probably not
necessary to rebuild one; especially considering what happened to the
one Armstrong was flying. :-)

It is worth noting that *after* Armstrong came within 0.2 s of dying in
this beast, and after he landed on the Moon, he repeated fought any
attempt to shut down the Flying Bedstead. He really believed that it was
the best tool available for training a pilot to land on the Moon.

That's particularly telling given that much of Armstrong's work on the
X-15 was getting the simulator to work, and because of that, he had a
lot to do with the Apollo simulators.


To give you some idea of how well the modern simulators work, all the
original batch of F-117 stealth fighter pilots made their first flights
in the aircraft solo and at night- and that was around twenty years ago.

I'm willing to bet that every one of those first flights was by a guy
who had flown other airplanes, landed other airplanes, and flown other
airplanes at night. Heck, I'm even willing to bet that on their first F-
117 landing, they could do a "go around" if things weren't quite right.
--
Kevin Willoughby lid

In this country, we produce more students with university degrees
in sports management than we do in engineering. - Dean Kamen

From Henry Spencer:
Pat Flannery wrote:
deal with- crosswinds, gusts, and turbulence that may arise unexpectedly
as it comes in to land. The Moon doesn't suffer from those problems, so
the landing is a fairly straightforward application of Newtonian physics.

The details matter, unfortunately.

For example, the Apollo commanders noted that you had to tilt the LM *way*
over to get substantial motion going -- it wasn't at all like a helicopter
in that respect. (Note that the LLRVs and LLTVs had their big G-canceling
jet engine on gimbals, precisely so tilting the vehicle *didn't* give you
any thrust vectoring on it, to simulate this.)

Note also that major revisions were made to the LM control software
between Apollo 9 and Apollo 10, because in-space testing on Apollo 9
exposed some serious problems in the autopilot algorithms used for manual
flying. Newtonian physics it may be, but it's not at all straightforward
when applied in large doses. :-)

...a helicopter
would make a far safer alternative, and probably fly far more like the
actual lander than the Harrier would.

Neither one is a very good simulation, unless perhaps you apply a generous
dose of fly-by-wire to change the handling.

No amount of fly-by-wire control law changes to a Harrier or helicopter
could enable the vehicle to simulate the pitch/roll angles of lunar
flying. Newton says that you must either gimbal the thrust vector
(LLTV solution) or gimbal the cockpit.

Knowing this, if anyone still advocates a radically modded Harrier-type
vehicle, keep in mind that the prototype that was to become the
Harrier, the Hawker P.1127, was designed in the 50's and had its first
flight in 1960, almost a full decade prior to the first Apollo landing.
It was not used then to train Apollo astronauts and I am certain that
it would be negative training for CEV-era astronauts.

Regarding land-based simulation, people seem to be talking like there
have been leaps and bounds of technical advancement. On the contrary,
I see little significant in advancement in that area since the 1970's.
While there has been a huge reduction in cost and increase in
reliability, the capability has existed for several decades.

The biggest shortcoming of ground-based simulators is that there is no
way to accurately simulate the acceleration cues sensed by the inner
ear and felt by the body. The simulator that comes closest to doing
this is the Vertical Motion Simulator out at Ames, and even that is
extremely restricted in range of motion - and only in two axes. It
might be possible to reattempt building a full blown 3-axis simulator
like Langley's LLRF, but to solve the transport lag and oscillation
problems of that rig (which made it all but useless in comparison to
the LLTV training) would require much more money than building a fleet
of flying training vehicles from scratch.

And let's also keep in mind that this whole discussion is predicated on
the notion that the lander will be manually flown. There would be a
huge cost savings for the program if it were designed to autoland
(minimizing manual crew input to a landing site redesignation for the
autopilot).

But I'm hoping that, unlike the X-38, NASA decides to keep the pilot in
the loop. Just for the adventure factor if nothing else (a la shuttle
landing mode). Depending on how adequately this program gets funded,
we may end up seeing NASA go with the Atari solution:

http://www.flippers.com/images/Atari...nder-4wtmk.jpg

Ha!

Seriously now, I would like to see a fleet of flight-based trainers
built from scratch. It would essentially be an improved LLTV. To
redress the lessons learned from the three near-fatalities along with
the other serious problems encountered in the LLRV/TV program, the
improved LLTV would have increased main engine thrust, increased
control authority to counter wind reaction, increased structural
integrity and increased reliability. I would also like to see it
designed with a ballistic parachute as well as a self-righting ejection
seat to give the option of saving the vehicle along with the pilot.

So my vote is 'yes', a new LLTV is needed.


~ CT

Pat Flannery wrote:

To give you some idea of how well the modern simulators work, all the
original batch of F-117 stealth fighter pilots made their first flights
in the aircraft solo and at night- and that was around twenty years ago.

Given the restrictions on when a F-117 could be flown twenty years
ago, I suspect the simulators had zip point **** to do with it.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL