Document:

ASSIGNMENT

         WHEREAS, I John J. Dupont, a citizen of the United States, residing at
Lawrenceville, Georgia, am the inventor of an invention in AUTOMATIC FLAT RATE
SETTING SYSTEM FOR FREIGHT FEEDER AIRCRAFT AND METHOD OF SETTING OF ENGINE FLAT
RATE for which I have executed an application for Letters Patent of the United
States on May 24, 2000; and

         WHEREAS, American Utilicraft Corporation, organized and existing under
the laws of the State of Delaware and having a place of business at 300 Petty
Road NE, Suite B, Lawrenceville, GA 30043 is desirous of obtaining the entire
right, title and interest in, to and under the said invention and the said
application;

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged and in fulfillment of my
pre-existing obligation of assignment contained in and subject to the revocation
provisions of my employment agreement dated February 28, 1991 with the said
American Utilicraft Corporation ("the Employment Agreement"), I, the said John
J. Dupont have sold, assigned, transferred and set over, and by these presents
do hereby sell, assign, transfer and set over, subject to the right of
revocation as set forth in the Employment Agreement, unto the said American
Utilicraft Corporation, its successors, legal representatives and assigns, the
entire right, title and interest in, to and under the said invention, and the
said application and all divisions, renewals and continuations thereof, and all
Letters Patent of the United States which may be granted thereon and all
reissues and extensions thereof, and all applications for Letters Patent which
may hereafter be filed for said invention in any country or countries foreign to
the United States, and all Letters Patent which may be granted for said
invention in any country or countries foreign to the United Stats and all
extensions, renewals and reissues thereof and all rights of priority in any such
country or countries based upon the filing of the said application for Letters
Patent of the United States which are created by any law, treaty or
international convention; and I hereby authorize and request the Commissioner of
Patents of the United States, and any Official of any county or countries
foreign to the United States, whose duty it is to issue patents on applications
as aforesaid, to issue all Letters Patent for said invention to the said
American Utilicraft Corporation, its successors, legal representatives and
assigns, in accordance with the terms of this instrument.

         AND I HEREBY covenant that I have full right to convey the entire
interest herein assigned, and that I have not executed, and will not execute,
any agreement in conflict herewith.

         AND I HEREBY further covenant and agree that I will communicate to said
American Utilicraft Corporation, its successors, legal representatives and
assigns, any facts known to me respecting said invention, and testify in any
legal proceeding, sign all lawful papers, execute all divisional, continuing and
reissue applications, make all rightful oaths and generally do everything
possible to aid the said American Utilicraft Corporation, its successors, legal
representatives and assigns, to obtain and enforce proper patent protection for
said invention in all countries.

         IN TESTIMONY WHEREOF, I hereunto set my hand and seal this 25th day of
May, 2000.

                                   /s/ John J. Dupont                    L.S.
                                   --------------------------------------
                                   John J. Dupont<PAGE>   1
                                                                    EXHIBIT 4.1

THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "ACT"), OR UNDER ANY STATE SECURITIES LAWS. THESE SECURITIES ARE
SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND MAY NOT BE
TRANSFERRED, SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF A
REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO THESE SECURITIES UNDER THE ACT
OR APPLICABLE STATE SECURITIES LAWS OR AN OPINION OF COUNSEL SATISFACTORY TO THE
COMPANY THAT ANY PROPOSED TRANSFER OR RESALE IS IN COMPLIANCE WITH THE ACT AND
ANY APPLICABLE STATE SECURITIES LAWS.

                                   ----------

                           CONVERTIBLE PROMISSORY NOTE

                                       OF

                             QUENTRA NETWORKS, INC.

$1,848,000                                                     October 6, 2000

         This Convertible Promissory Note (this "NOTE") is made and delivered as
of October 6, 2000, by Quentra Networks, Inc., a Delaware corporation f/k/a
Coyote Network Systems, Inc. ("COMPANY") with its principal executive offices at
1640 S. Sepulveda Boulevard, Suite 222, Los Angeles, CA 90025, and Omega Capital
Partners, L.P., a Delaware limited partnership ("HOLDER"), with its principal
address: c/o Omega Advisors, Inc., Wall Street Plaza, 88 Pine Street, 31st
Floor, New York, NY 10005.

         WHEREAS, on March 31, 2000, the Company issued to First Venture
Leasing, LLC, a Delaware limited liability company ("First Ventures"), a warrant
(the "Original Warrant") to purchase 500,000 shares of the Company's common
stock, $1.00 par value (the "Common Stock");

         WHEREAS, on March 31, 2000, First Venture assigned all of its right,
title and interest to purchase 168,000 shares of Common Stock (the "Warrant")
under the Original Warrant to Holder in accordance with a properly executed
Notice of Transfer signed by First Venture, Holder and the Company in accordance
with the terms of the Original Warrant; and

         WHEREAS, the Company never issued a new certificate evidencing the
Warrant to Holder; and

         WHEREAS, the Company has agreed to issue and sell this Note to Holder
in consideration of First Venture surrendering the Original Warrant to the
Company for cancellation and Holder's agreement to cancel the Warrant.

<PAGE>   2

         NOW, THEREFORE, in consideration of the foregoing recitals and the
mutual promises hereinafter set forth, the Company hereby issues this Note to
Holder on the terms and conditions set forth herein:

         The Company hereby promises to pay to Holder or its permitted assigns,
the principal amount of One Million Eight Hundred Forty-Eight Thousand Dollars
($1,848,000), together with interest on the principal amount hereof outstanding
from time to time accrued at a rate per annum equal to eight percent (8%),
calculated on the basis of a 365 day year (the "Note Interest Rate"), from and
after the date hereof, compounded on a monthly basis and payable quarterly on
the last business day of each December, March, June and September during such
time as this Note remains outstanding, in whole or in part, beginning on
December 29, 2000. Subject to Section 6 hereof, the outstanding principal amount
of this Note, together with all accrued and unpaid interest thereon, shall be
payable on October 6, 2005 (the "SCHEDULED REPAYMENT DATE") unless this Note
shall have been previously converted in full pursuant to Section 1 hereof. All
payments under this Note shall be payable, at the Holder's sole discretion,
either at the principal offices of the Company or by wire transfer to an account
designated by the Holder to the Company at least two (2) business days prior to
the scheduled payment date. At any time after October 6, 2001, the Holder shall
have the right to demand payment, in whole or in part, of the outstanding
principal amount of this Note, together with all accrued and unpaid interest
thereon, upon thirty (30) days prior written notice to the Company. At any time
after the closing sales price of the Common Stock equals or exceeds $6.00 per
share for a period of twenty (20) consecutive trading days, the Company may, at
its option, prepay at any time thereafter, in whole or in part, the outstanding
principal amount of this Note, together will all accrued and unpaid interest
thereon, prior to the Scheduled Repayment Date upon providing Holder sixty (60)
days prior written notice, which notice shall set forth the prepayment date (the
"EARLY PREPAYMENT DATE") and the principal amount, including all accrued
interest thereon, to be prepaid. Prior to the Early Prepayment Date, the Holder
may continue to exercise its Conversion Right as set forth in Section 1 hereof.

         The following is a statement of the rights of the Holder of this Note
and the conditions to which this Note is subject, and to which the Holder
hereof, by the acceptance of this Note, agrees:

         1. CONVERSION. (a) The Holder shall have the right at any time, in its
sole discretion, to convert all or any part of the then outstanding principal
amount of, and accrued and unpaid interest under, this Note (the "CONVERSION
RIGHT") into such number of shares of Common Stock (the "SHARES") as shall be
obtained by dividing (i) the portion of such outstanding principal amount and
accrued and unpaid interest with respect to which the Conversion Right is then
being exercised by (ii) $3.25 (as adjusted for any stock splits, stock dividends
and/or recapitalizations after the date hereof) (the "CONVERSION PRICE").

         (b) The Holder shall be entitled to exercise the Conversion Right upon
written notice to the Company of its intention to so exercise, in the form
attached hereto as Exhibit A (the "Conversion Notice"), given at least five (5)
calendar days prior to the effective date of such exercise.

<PAGE>   3

               (c) The Conversion Right may be exercised for, at the Holder's
sole discretion, the full amount, or less than the full amount, of the then
outstanding principal amount of, and accrued and unpaid interest under, this
Note. Upon any such partial exercise, the Company at its expense will forthwith
issue to Holder a new Note or Notes of like tenor in the amount of principal and
accrued and unpaid interest as to which the Conversion Right has not been
exercised, such Note or Notes to be issued in the name of the Holder.

         2. ISSUANCE OF CONVERSION STOCK. Within one (1) business day after the
applicable date of conversion of this Note under Section 1, the Company at its
expense will cause to be issued in the name of and delivered to the Holder of
this Note, a certificate or certificates for the number of shares of Common
Stock to which the Holder shall be entitled upon such conversion (bearing such
legends as may be required by applicable state and federal securities laws in
the reasonable opinion of legal counsel of the Company). No fractional shares
will be issued upon conversion of this Note. If upon any conversion of this Note
a fraction of a share would otherwise result, then in lieu of such fractional
share the Company will pay the cash value of that fractional share, calculated
on the basis of the Conversion Price.

         3. REGISTRATION STATEMENT. Within 120 days following the date hereof,
the Company shall file with the Securities and Exchange Commission a
registration statement covering the sale or other distribution of all shares of
Common Stock issuable upon exercise of the Conversion Right. If such
registration statement is not filed within 120 days following the date hereof,
then (anything in this Note to the contrary notwithstanding) the Note Interest
Rate shall increase by one percent (1%) per annum, prospectively, for each
thirty (30) day period, or portion thereof, following such 120 day period,
during which such registration statement remains unfiled; provided, however,
that in no event shall the Note Interest Rate exceed a maximum of twelve percent
(12%) per annum. The Company shall use its best efforts to cause such
registration statement to be declared effective as soon as practicable
thereafter. The Company shall use its best efforts to keep such registration
statement effective until the earlier of (i) the repayment in full of, and the
payment of all accrued interest under, this Note, or (ii) such time as the
Shares issuable upon conversion of this Note could be sold pursuant to Rule
144(k) as promulgated under the Act. The Company and Holder each agree to take
such action as is reasonably requested by the other party to give effect to the
intention of the provisions set forth in this Section 3 and to comply with the
Act, the rules and regulations promulgated thereunder or other applicable
securities laws and regulations.

<PAGE>   4
         4. REPRESENTATIONS AND WARRANTIES.

               4.1. REPRESENTATIONS AND WARRANTIES OF THE COMPANY.

               (a) This Note has been duly executed and delivered by the Company
and constitutes the legal, valid and binding obligation of the Company,
enforceable against the Company in accordance with its terms.

               (b) If at the time of any conversion of this Note, the number of
authorized but unissued shares of Common Stock shall not be sufficient to effect
such conversion of this Note, then the Company will take such corporate action
as may, in the reasonable opinion of its legal counsel, be necessary to increase
its authorized but unissued shares of Common Stock to such number of shares of
Common Stock as shall be sufficient for such purpose. The Company shall at all
times reserve for issuance a sufficient number of shares of authorized Common
Stock sufficient to effect the conversion in full of this Note.

               (c) No consent, approval or authorization of any third party is
required for the execution, delivery and performance of this Note by the Company
which has not been received, and the execution, delivery and performance of this
Note do not and will not violate, conflict with, result in a violation or breach
of, or constitute a default under, any law, rule, regulation or judicial or
administrative decision to which the Company may be subject, the Company's
Certificate of Incorporation or By-Laws, or any indenture, agreement or
instrument to which the Company or any of its property is subject, or which
would create a mortgage, pledge, lien, charge, debenture, assignment,
hypothecation or security interest or any other agreement or arrangement having
the effect of conferring security (hereinafter a "Lien") or restriction of any
kind upon the Company or any of its property or revenues.

               (d) All shares of Common Stock issued upon the conversion of this
Note shall be validly issued, fully paid and non-assessable.

               4.2. REPRESENTATIONS AND WARRANTIES OF HOLDER.

               (a) The Holder has all necessary power and authority to execute
and deliver this Note, to perform its obligations under this Note and to
consummate the transactions contemplated by this Note. The execution and
delivery of this Note and the consummation by the Holder of the transactions
contemplated hereby have been duly and validly authorized by all necessary
action, and no other proceedings on the part of the Holder are necessary to
authorize this Note or to consummate the transactions contemplated hereby. This
Note constitutes a legal, valid and binding obligation of the Holder,
enforceable against it in accordance with its terms.

               (b) The Holder has legal, valid, beneficial and exclusive title
to the Warrant, free and clear of all encumbrances other than those imposed by
the Act.

               (c) The undersigned represents and warrants that it is an
"accredited investor" as that term is described in Rule 501 of Regulation D of
the Act.

<PAGE>   5

               (d) The undersigned understands that this Note and the Shares
have not been registered under the Act or under any applicable state securities
laws, but are offered pursuant to an exemption from registration under the Act.

               (e) The undersigned understands and agrees that this Note and the
Shares will be restricted securities and that any and all certificates
representing this Note and the Shares will bear a restrictive legend indicating
that: (1) this Note and the Shares have not been registered under the Act; and
(2) that this Note and the Shares are subject to restrictions on transfer and
resale and may not be transferred or resold except as permitted by the Act, and
applicable state securities laws, pursuant to registration or exemption
therefrom. The undersigned understands that for these and other reasons the
undersigned may not be able to liquidate an investment in this Note or the
Shares for an indefinite period.

               (f) Unless specifically provided for herein, the undersigned
understands that this Note and the Shares may not be mortgaged, pledged,
hypothecated or otherwise transferred or offered to be so transferred without an
effective registration statement for this Note or Shares under the Act, and the
regulations promulgated pursuant thereto and any applicable state securities law
(unless exempt therefrom), and without compliance with the requirements set
forth herein.

               (g) The undersigned represents and warrants that the undersigned
is purchasing the securities for the undersigned's own account and not as
nominee for, on behalf of, for the beneficial interest of, or with the intention
to transfer to, any other person, trust, or other entity, for long-term
investment, and without the intention of reselling or redistributing the
securities.

               (h) The undersigned is informed of the significance to the
Company of the foregoing representations, and such representations are made with
the intention that the Company will rely on them.

         5. NO RIGHTS OR LIABILITIES AS STOCKHOLDER. This Note does not by
itself entitle the Holder to any voting rights or other rights as a stockholder
of the Company. In the absence of conversion of this Note, no provisions of'
this Note, and no enumeration herein of the rights or privileges of the Holder,
shall cause such Holder to be a stockholder of the Company for any purpose.

         6. DEFAULT. The Company will be in default if any of the following
happens:

               (a) failure of the Company to pay any part of the principal of
this Note as and when due, or any interest hereunder within ten (10) calendar
days after the due date thereof;

               (b) any default in the performance of any other obligation of the
Company hereunder, which default is not cured within a thirty (30) day period
after the Holder has given the Company written notice of such default;

<PAGE>   6

               (c) any adjudicated default in the performance of any other
obligation of the Company in excess of $500,000, which default is not cured
within thirty (30) days after the date of such adjudication (provided, the
Company agrees to promptly notify Holder of any third party claim alleging a
default in the Company's performance of its obligations, which claim is in
excess of $100,000); or

               (d) (i) a receiver is appointed for the Company or its property
or the Company is liquidated or dissolved, (ii) the Company makes an assignment
for the benefit of its creditors or (iii) any proceeding is commenced by, for or
against the Company under any bankruptcy, insolvency or debtor's relief law for
the purpose of seeking a reorganization of the Company's debts, and such
proceeding is not dismissed within ninety (90) calendar days of its
commencement;

         whereupon, in each and every such case, the Holder of this Note may by
notice in writing to the Company declare all or any part of the unpaid principal
balance and accrued interest thereon then outstanding hereunder to be forthwith
due and payable, whereupon the same shall immediately become due and payable,
and the Holder of this Note may proceed to enforce payment of such outstanding
balance or part thereof in such manner as said Holder may elect.

         7. ACKNOWLEDGEMENT. Holder acknowledges and agrees that upon its
acceptance of this Note, the Warrant will be cancelled and no longer be of any
force or effect.

         8. WAIVER AND AMENDMENT. This Note may be extended, and any term of
this Note may be amended, and the observance of any term of this Note may be
waived (either generally or in a particular instance and either retroactively or
prospectively), only with the written consent of the Company and the Holder.
Upon the effectiveness of any such action, the Company will promptly give
written notice thereof to the Holder.

         9. ASSIGNMENT. No party shall assign or transfer all or any part of
this Note, or any interest therein, without the prior written consent of the
other party. The rights and obligations of the Company and the Holder shall be
binding upon and benefit the successors, heirs, administrators and permitted
assigns of the parties.

         10. NO IMPAIRMENT. The Company will not, by amendment of its
Certificate of Incorporation, any certificate of designations or bylaws or
through any reorganization, recapitalization, transfer of assets, consolidation,
merger, dissolution, issue or sale of securities or any other voluntary action,
avoid or seek to avoid the observance or performance of any of the terms to be
observed or performed hereunder by the Company, but will at all times in good
faith assist in the carrying out of all of the provisions of this Note and in
the taking of all such action as may be necessary or appropriate in order to
protect the rights of the Holder against impairment.

         11. HEADINGS. The headings in this Note are for purposes of convenience
in reference only, and shall not be deemed to constitute a part hereof.

<PAGE>   7

         12. NOTICES. Any notice required to be given or delivered to the
Company under the terms of this Agreement shall be in writing and addressed to
the President of the Company at its principal corporate offices as set forth in
the introductory paragraph hereof. Any notice required to be given or delivered
to the Holder shall be in writing and addressed to the Holder at the address
indicated for the Holder in the introductory paragraph hereof or to such other
address as such party may designate in writing from time to time to the Company.
All notices properly addressed shall be deemed to have been given or delivered
upon: personal delivery; three (3) days after deposit in the United States mail
by certified or registered mail (return receipt requested); one (1) business day
after deposit with any return receipt express courier (prepaid); or one (1)
business day after transmission by facsimile or telecopier, with confirmed
answerback.

         13. GOVERNING LAW AND JURISDICTION. This Note shall be construed and
enforced in accordance with, and governed by, the internal laws of the State of
New York applicable to contracts entered into between residents of that state
and to be wholly performed in that state. Each of the parties hereto irrevocably
consents and submits to the exclusive jurisdiction and venue of any court within
the Borough of Manhattan, City of New York, State of New York, in connection
with any matter based upon or arising out of this Note or the matters
contemplated herein, and hereby waives any objection thereto based on forum non
conveniens or any other legal or equitable doctrine.

<PAGE>   8

         IN WITNESS WHEREOF, the undersigned has caused this Note to be signed
in its name as of the date first above written.

QUENTRA NETWORKS, INC.                         OMEGA CAPITAL PARTNERS, L.P.
                                               BY: OMEGA ASSOCIATES, LLC,
                                                   GENERAL PARTNER

By: /s/ Timothy G. Atkinson                    By: /s/ David Bloom
    -----------------------------                  ----------------------------
Name:  Timothy G. Atkinson                     Name: David Bloom
Title: General Counsel                         Its:  Member

<PAGE>   9

                                    EXHIBIT A

                              NOTICE OF CONVERSION

                   [To be signed only upon conversion of Note]

To:   QUENTRA NETWORKS, INC.

         The undersigned, the Holder of the within Note, hereby elects to
convert [ALL/$_____] of the principal and accrued and unpaid interest thereon
into ___________ shares of Common Stock of Quentra Networks, Inc., such
conversion to be effective on _________ __, 200_, as provided for therein.

         In converting this Note, the undersigned hereby confirms and
acknowledges that the shares of Common Stock to be issued upon such conversion
are being acquired solely for the Holder's own account and not as a nominee for
any other party, and for investment, and that the Holder will not offer, sell or
otherwise dispose of any such securities except under circumstances that will
not result in a violation of applicable federal and state securities laws.

         Please issue a certificate or certificates representing said shares of
Common Stock in the name of the undersigned or in such other name as is
specified below:

Dated:
      ----------------------------               ------------------------------
                                                 NAME

                                                 By:
                                                    ---------------------------
                                                    (Signature must conform in
                                                    all respects to name of
                                                    Holder as specified on the
                                                    face of the Note)

Address:

-------------------------

-------------------------

-------------------------

<PAGE>   10

                                   SCHEDULE A

         The Company also issued Convertible Promissory Notes (the "Notes") to
the following holders, which Notes are the same in all material respects expect
for the information set forth below:

<TABLE>
<CAPTION>
                                                                       Amount of Convertible
              Name of Holder                        Number of Shares      Promissory Note
-----------------------------------------------     ----------------   ---------------------
<S>                                                 <C>                <C>
Omega Institutional Partners, L.P.                             7,400      $        81,400
-----------------------------------------------      ---------------      ---------------
Omega Capital Investors, L.P.                                 15,100      $       166,100
-----------------------------------------------      ---------------      ---------------
Omega Overseas Partners, Ltd.                                150,400      $     1,654,400
-----------------------------------------------      ---------------      ---------------
The Common Fund                                               17,100      $       188,100
-----------------------------------------------      ---------------      ---------------
HH Manased Account 5 Limited                                   4,400      $        48,400
-----------------------------------------------      ---------------      ---------------
Beta Equities, Inc.                                           89,900      $       988,900
-----------------------------------------------      ---------------      ---------------
Goldman Sachs & Co. Profit Sharing Master                     19,100      $       210,100
-----------------------------------------------      ---------------      ---------------
Citi Omega Ltd.                                                6,000      $        66,000
-----------------------------------------------      ---------------      ---------------
Ministers & Missionaries Benefit Board of                     22,600      $       248,600
American Baptist Churches
-----------------------------------------------      ---------------      ---------------
TOTAL                                                        332,000      $     3,652,000
===============================================      ===============      ===============
</TABLE>

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