The Materials You Need When You Need Them

How exactly did Hiperco 501 allow Captain Sullenberger to safely land his Airbus in the Hudson River and save the day?

On January 15, 2009 bird strikes on US 1549 shortly after takeoff from New York's LaGuardia airport resulted in loss of power in both main engines. Fortunately, these planes have both an "APU" (auxiliary power unit) and a "RAT" (ram air turbine). Both of these are electric generators made with Hiperco 50 rotors and stators. The RAT and APU provided the emergency power that enabled Captain Sullenberger to make the needed flight maneuvers to bring US 1549 down safely.

*The aircraft’s main generators also have Hiperco 50, but since they are driven by the main engines, they could no longer supply power.


Was it the magnetic field strength and high power/weight ratio of Hiperco 50?

YES! One of the reasons these generators use Hiperco 50 and not some other soft magnetic alloy, is because Hiperco 50 provides the maximum power in terms of strength to weight ratio. That is why Hiperco 50 is specified for use in APUs and RATs, as well as in the main generators.


Would another soft magnetic alloy also have worked?

NO! Other soft magnetic alloys would require more space, and would add more weight to deliver the same amount of power that Hiperco 50 can. In fact, Hiperco 50 is the only soft magnetic alloy that can provide the required electrical energy given the allowable weight parameters.


Have RAT and APU systems with Hiperco 50 saved lives before?

Yes, on at least three other occasions:

  • On 7/23/83 Air Canada flight 143 from Montreal to Edmonton where an emergency landing was undertaken at Gimli, Manitoba due to fuel starvation
  • On 7/12/00 Hapag-Lloyd flight 3378 from Crete, Greece to Hannover, Germany an emergency landing due to fuel exhaustion was undertaken short of Vienna, Austria
  • On 8/24/01 Air Transat flight 236 from Toronto, Canada to Lisbon Portugal an emergency landing due to fuel starvation was undertaken at Lajes Air Force Base, Azores, Portugal.

Between these three events, and the “Miracle on the Hudson” event, 689 lives have been saved.



Important Magnetism Terms

Magnetic Field Strength, H — The value of the magnetizing field. Sometimes H is called the applied field. It is measured in Oersteds.

Magnetic Induction, B — The resultant magnetic field caused by a magnetizing field, H. Sometimes B is called the induced field. B is measured in Gausses

Permeability, u — The ratio of induction, B, to the magnetic field strength H, that produced the induction. The unit has no dimensions.

Coercive Force, Hc — The magnetic field strength, H, required to restore the magnetic induction, B, to zero.

Magnetic Hysteresis — The property exhibited by the lack of correspondence between the changes in induction resulting (from?) increasing magnetic B field strength and from decreasing magnetic B field strength

Core Loss, Pc — power expended in an AC circuit at a certain B field induction and frequency. Units are in Watts per lb.





BH Loop for Hiperco 50



For information on Hiperco 50/50A DC and AC Magnetic Properties, Physical and Mechanical Properties, Chemistry, Specifications and forms available from stock; download a copy of our Hiperco 50/50A data sheet.


For information on all our Soft Magnetic Alloys 50/50A DC and AC Magnetic Properties, Physical and Mechanical Properties, Chemistry, Specifications and forms available from stock; download a copy of our Soft Magnetic Alloys data sheet.

Or call us now to speak with an EFI materials expert or to place an order.

1 Hiperco 50 and Hiperco 50A are trademarks of Carpenter Technology Corp., Reading PA