1
                                   EXHIBIT 11.
                 STATEMENT RE: COMPUTATION OF EARNINGS PER SHARE



THREE MONTH PERIOD ENDED MARCH 31, 1998
                                                                   ASSUMING
                                                    BASIC         DILUTION (2)
                                                    -----         ------------
                                                                   
WEIGHTED AVERAGE OF OUTSTANDING SHARES            32,819,641      32,819,641

COMMON EQUIVALENT SHARES:
     OUTSTANDING STOCK OPTIONS                    N/A              1,330,710

OTHER POTENTIALLY DILUTIVE SECURITIES:
     CONVERTIBLE NOTES (1)                        N/A              3,571,429
                                                  ----------     -----------

SHARES USED IN COMPUTING
NET INCOME PER COMMON SHARE                       32,819,641     37,721,780
                                                  ==========     ==========


NET INCOME                                        $ 6,519,000    $ 6,519,000

ADJUSTMENTS ASSUMING DILUTION:
     INTEREST EXPENSE ADJUSTMENT, NET OF TAXES    N/A                850,116
                                                  -----------    -----------

NET INCOME                                        $ 6,519,000    $ 7,369,116
                                                  ===========    ===========

NET INCOME PER COMMON SHARE                       $      0.20    $      0.20
                                                  ===========    ===========

NOTES:


(1)-     On September 16, 1997, the company sold $100 million of 5% convertible
         subordinated notes due October 2002. The notes are convertible at the
         option of the holders into Orbital common stock at a conversion price
         of $28.00 per share.

(2)-     Subsidiary stock options that enable holders to obtain subsidiary's
         common stock pursuant to effective stock option plans are included in
         computing the subsidiary's earnings per share, to the extent dilutive.
         Those earnings per share data are included in the Company's per share
         computations based on the Company's holdings of the subsidiary's stock.
         For the three months ended March 31, 1998, all such subsidiary stock
         options were anti-dilutive.