1. Headquarters Fleet Air Arm
MRH90 and TopOwl
Navy Flight Trials
2010 AMMA/JHC
Symposium
DR Glenn PascoeDR Glenn Pascoe
MBBS, FRACGP, DAvMedMBBS, FRACGP, DAvMed
Senior Medical Advisor Aviation MedicineSenior Medical Advisor Aviation Medicine –– NavyNavy
(Wing Commander, RAAFSR)(Wing Commander, RAAFSR)

2. Acknowledgment
LCDR Brad MacKay
Chief of Flight Test, AMAFTU
Headquarters Fleet Air Arm

3. Headquarters Fleet Air Arm
• TopOwl Helmet
•AMAFTU MRH90 FOCFT
Scope

4. MRH90
• NHIndustries NH90
– Tactical Transport Helicopter (TTH) vs NATO Frigate
Helicopter (NFH)
• Troop lift (embarked and land based)
• Fly by wire, retractable U/C,
• Glass and carbon fibre composites
• MTOW > SK50
• Rear loading ramp
• Manual fold blades and tail pylon
Headquarters Fleet Air Arm

5. Aircraft Maintenance and
Flight Trials Unit
• AMAFTU
– develop aircraft modifications
– maintenance and operational procedures
– evaluate through flight test new and
modified configurations, procedures and
equipment
– ADF’s centre of expertise for ship/helicopter
First of Class Flight Trials (FOCFT),
– Ship/Helicopter dynamic interface
assessments (Embarked Flight Trials)
Headquarters Fleet Air Arm

6. FOCFT Test – What is it?
Headquarters Fleet Air Arm
• Where the suitability of the ship /
aircraft combination is assessed.
• Ship just as much as aircraft focused
• Outputs not only limited to SHOL
– Maintenance & support facilities just as
important
• Testing to define safe operational
capability of ship / aircraft combination

7. TopOwl helmet mounted
sight and display system
• Valid engineering trade-offs:
– Good: See through capability, mass, CG,
– Bad: Hyperstereopsis, lower performance
Headquarters Fleet Air Arm

8. Headquarters Fleet Air Arm
Binocular Cues for Depth
perception
• Stereopsis - Angle of disparity
• Accommodation
• Convergence

9. Headquarters Fleet Air Arm
Hyperstereopsis
• An illusion created when each eye
views an image from sensors with an
interpupillary distance greater than
that of the human eyes

10. Headquarters Fleet Air Arm
Hyperstereopsis - Effects
• Absolute distance perception
– Objects appear closer
Right I² Tube
Target point
Real
distance
of object
in the
scene
I² tube optical axes
Left I² Tube
D
Normal IPD
DD



Perceived
distance
of object
in the
scene

11. • Magnification of depth
– objects appear stretched, out of shape
Headquarters Fleet Air Arm
Hyperstereopsis - Effects

12. • Overlapping objects
– If enough light to see object unaided, NVD
image will be over-layed on real world
image
– May see three objects instead of one
Headquarters Fleet Air Arm
Other TopOwl issues

13. • Colour vision
– ADF allows for slightly colour
defective aircrew applicants (CP2)
– Optics of the TopOwl visor results
in effectively looking through a
“green blocker” when visor is
down
– Will CP2 pilots be safe?
– Is reflected wavelength band
narrow enough to not be a
problem?
– What about LED lights?
Headquarters Fleet Air Arm
Other TopOwl issues

14. TopOwl and deck operations
• Compensation for visual distortion is necessary
on initial exposure
– Adaptation to absolute distance perception
occurs fairly rapidly (5hrs initially then 10-
20mins for re-adaptation)
– Adaptation to magnification of depth (‘arm
stretch’ or slope perception) not complete
• USMC concluded that use of Top Owl was
unacceptable for deck operations
– Different aircraft
Headquarters Fleet Air Arm

15. Results of Testing – TopOwl
• AS350 trial: approximately 60hrs
– Seated height appeared slightly lower than
normal
– Different ‘apparent’ seated height unaided/aided:
– Transition from aided to unaided flight
Unsatisfactory
Headquarters Fleet Air Arm

16. Results of MRH90 Testing –
TopOwl
• MRH90 trial: approximately 10hrs
work-up and 10 hrs at sea
– Adaptation was Satisfactory
• Misjudged distance mitigated
– Normal wheeled a/c landing technique
• Establish ROD during quiescent period and
land firmly
– Height estimation assisted by RADALT
– ACMN wearing ANVIS-9 NVD
– Unfamiliar objects appear closer
Headquarters Fleet Air Arm

17. Results of MRH90 Testing –
TopOwl
• Peripheral Cues
– Enhancing feature
– Allows peripheral scanning of a lit deck
Headquarters Fleet Air Arm

18. FOCFT–Specifics of Flight Test
• Instrumentation
• Deck Modelling
– deck motion limits with/without lashings
• Shore based testing
– Initial TopOwl NVD flight testing in AS350
– Low speed handling/ data collection
– Simulated deck operations
• Sea Testing
– Interface Testing
– SHOL development
Headquarters Fleet Air Arm

19. FOCFT – Specifics of
Interface Testing
• Deck interface & facilities examples
– Ranging & stowing aircraft
– Folding / spreading
– Maintenance & support facilities
– Hanger suitability
– Maintenance supervision
– Aircrew briefing / mission planning
– Weapons prep / loading aspects
– Ship-based aviation facilities
Headquarters Fleet Air Arm

20. Results of MRH90 FOCFT
Headquarters Fleet Air Arm
• 18 days at sea
• 19 Test Sorties
• 252 Deck Landings (172 Day / 80 Night)
• 36 Utility operations
• Overall, Very Large Envelopes (SHOLs)
• 4 Major deficiencies identified