Method of building an expulsive blanket using composite materials and stitched attachment

• US 5,531,405 A
• Filed: 08/23/1994
• Issued: 07/02/1996
• Est. Priority Date: 08/23/1994
• Status: Expired due to Term

• Current Assignee: Hamilton Sundstrand Corporation (Rtx Corporation)
• Original Assignee: Control Dynamics, Inc.
• Inventors: Goldberg, Joshua I.
• Primary Examiner(s): Barefoot, Galen L.
• Application Number:
  US08/294,640
• Time in Patent Office: 679 Days
• Field of Search: 244/134 R, 244/134 B, 244/134 D, 310/10
• US Class Current: 244/134.00B
• CPC Class Codes: B64D 15/163 using electro-impulsive devices

Abstract

A composite fabric electro-expulsive blanket is provided for shattering and removing ice and other fungible material from an accretion surface such as an airfoil. The blanket includes composite fabric upper and lower layers having a modulus of elasticity approximately between 10 to 100 million psi. Upper and lower conductor segments are positioned within the blanket so that when electrically energized, they repel one another so as to rapidly set the outer ice-accreting surface into motion. Bowed or loose stitches connecting the outer and inner layers become taut during the motion of the ice-accretion surface, thereby rapidly decelerating the surface and shattering accumulated ice thereon. Slits in the outer layer limit undesired hoop stress.

Claims

1. An electro-expulsive blanket for shattering and removing ice and other fungible material from an accretion surface such as an airfoil, comprising:

a composite fabric layer including a lower layer to be attached to a protected surface and an upper layer having an ice-accretion surface to be exposed to the elements, the composite fabric layer having a relatively high modulus of elasticity with respect to elastomeric materials so that energy is efficiently transferred to the composite fabric layer for rapid movement of the upper layer away from the lower layer when the blanket is energized;

a plurality of upper conductor segments periodically spaced from one another and forming two-dimensional patterns extending in a plane parallel to the ice-accretion surface, the upper conductor segments attached to the upper layer;

a plurality of lower conductor segments periodically spaced from one another and forming two-dimensional patterns extending in a plane parallel to the ice-accretion surface, the lower conductor segments attached to the lower layer, each of the lower conductor segments arranged in an underlying relationship to respective upper conductor segments, the upper and lower conductor segments to be connected to one or more power sources and arranged in such a way that the upper conductor segments move rapidly and upwardly away from the lower conductor segments and the lower layer when the upper and lower conductor segments are energized by an electric current, the upwardly moving upper conductor segments transferring their motion to the upper layer and the ice-accretion surface; and

stitches connecting the upper layer to the lower layer, the stitches being bowed or slack when the conductor segments are unenergized, the slack of the stitches allowing the upper layer to move rapidly away from the lower layer when the conductor segments are energized until the slack is exhausted and the stitches become taut, and the stitches becoming taut causing the upper layer to rapidly decelerate so as to shatter any ice which may have accumulated on the ice-accretion surface of the blanket.

2. An electro-expulsive blanket as defined in claim 1, wherein the composite fabric upper layer comprises an upper outer layer and an upper inner layer, the upper conductor segments being connected to the upper inner layer, and wherein the composite fabric lower layer comprises a lower outer layer and a lower inner layer, the lower conductor being connected to the lower inner layer, the stitches being connected to the upper inner layer and the lower inner layer.

3. An electro-expulsive blanket as defined in claim 1, further including an electrically insulating layer positioned between the upper and lower conductor segments.

4. An electro-expulsive blanket as defined in claim 1, further including elastomeric material filling a void between the upper and lower conductor segments, the elastomeric material attached to the upper and lower layers.

5. An electro-expulsive blanket as defined in claim 1, wherein the upper and lower layers are made from a composite fabric material having a modulus of elasticity approximately between 10 million and 100 million pounds per square inch.

6. An electro-expulsive blanket as defined in claim 1, wherein the stitches are threads of carbon filament or glass fiber.

7. An electro-expulsive blanket as defined in claim 2, wherein the upper outer layer of the blanket has a plurality of splits extending through the upper outer layer from the ice-accretion surface to a bottom surface of the upper outer layer, the splits being used for limiting hoop stress to acceptable levels when the blanket is fired so that the blanket does not structurally fail.

8. An electro-expulsive blanket as defined in claim 7, wherein the splits extend at oblique angles relative to the ice-accretion surface.

9. An electro-expulsive blanket for shattering and removing ice and other fungible material from an accretion surface such as an airfoil, comprising:

a composite fabric outer layer including a lower outer layer to be attached to a protected surface and an upper outer layer having an ice-accretion surface to be exposed to the elements, the composite fabric outer layer having a relatively high modulus of elasticity with respect to elastomeric materials so that energy is efficiently transferred to the composite fabric layer for rapid movement of the upper outer layer away from the lower outer layer when the blanket is energized;

a composite fabric inner layer including a lower inner layer attached to the lower outer layer and an upper inner layer attached to the upper outer layer;

a plurality of upper conductor segments periodically spaced from one another and forming two-dimensional patterns extending in a plane parallel to the ice-accretion surface, the upper conductor segments attached to the upper inner layer;

a plurality of lower conductor segments periodically spaced from one another and forming two-dimensional patterns extending in a plane parallel to the ice-accretion surface, the lower conductor segments attached to the lower inner layer, each of the lower conductor segments arranged in an underlying relationship to respective upper conductor segments, the upper and lower conductor segments to be connected to one or more power sources and arranged in such a way that the upper conductor segments move rapidly and upwardly away from the lower conductor segments and the lower layers when the upper and lower conductor segments are energized by an electric current, the upwardly moving upper conductor segments transferring their motion to the upper layers and the ice-accretion surface;

an electrically insulating layer positioned between the upper and lower conductor segments;

elastomeric material filling the void between the upper and lower conductor segments and the insulating layer, the elastomeric material attached to the upper and lower inner layers; and

stitches for connecting the upper inner layer to the lower inner layer, the stitches being bowed or slack when the conductors are unenergized, the slack of the stitches allowing the upper inner layer to move rapidly away from the lower inner layer when the conductor segments are energized until the slack is exhausted and the stitches become taut, and the stitches becoming taut causing the upper inner layer to rapidly decelerate so as to shatter any ice which may have accumulated on the ice-accretion surface of the blanket.

10. An electro-expulsive blanket as defined in claim 9, wherein the outer and inner layers are made from a composite fabric material having a modulus of elasticity approximately between 10 million and 100 million pounds per square inch.

11. An electro-expulsive blanket as defined in claim 9, wherein the stitches are threads of carbon filament or glass fiber.

12. An electro-expulsive blanket as defined in claim 9, wherein the upper outer layer of the blanket has a plurality of splits extending through the upper outer layer from the ice-accretion surface to a bottom surface of the upper outer layer, the splits being used for limiting hoop stress to acceptable levels when the blanket is fired so that the blanket does not structurally fail.

13. An electro-expulsive blanket as defined in claim 12, wherein the splits extend at oblique angles relative to the ice-accretion surface.

14. A composite fabric electro-expulsive blanket for shattering and removing ice and other fungible material from an accretion surface such as an airfoil, comprising:

a composite fabric outer layer including a lower outer layer to be attached to a protected surface and an upper outer layer having an ice-accretion surface to be exposed to the elements, the composite fabric outer layer having a relatively high modulus of elasticity with respect to elastomeric materials so that energy is efficiently transferred to the composite fabric outer layer for rapid movement of the upper outer layer away from the lower outer layer when the blanket is energized, the upper outer layer of the blanket having a plurality of splits extending through the upper outer layer from the ice-accretion surface to a bottom surface of the upper outer layer, the splits being used for limiting hoop stress to acceptable levels when the blanket is fired so that the blanket does not structurally fail;

a composite fabric inner layer including a lower inner layer attached to the lower outer layer and an upper inner layer attached to the upper outer layer, the outer layer and the inner layer each being made from a composite fabric material having a modulus of elasticity approximately between 10 million and 100 million pounds per square inch;

a plurality of upper conductor segments periodically spaced from one another and forming two-dimensional patterns extending in a plane parallel to the ice-accretion surface, the upper conductor segments attached to the upper inner layer;

a plurality of lower conductor segments periodically spaced from one another and forming two-dimensional patterns extending in a plane parallel to the ice-accretion surface, the lower conductor segments attached to the lower inner layer, each of the lower conductor segments arranged in an underlying relationship to respective upper conductor segments, the upper and lower conductor segments to be connected to one or more power sources and arranged in such a way that the upper conductor segments move rapidly and upwardly away from the lower conductor segments and the lower layers when the upper and lower conductor segments are energized by an electric current, the upwardly moving upper conductor segments transferring their motion to the upper layers and the ice-accretion surface;

an electrically insulating layer positioned between the upper and lower conductor segments;

elastomeric material filling the void between the conductor segments and the insulating layer, the elastomeric material attached to the upper and lower inner layers; and

stitches of threads of carbon filament or glass fiber for connecting the upper inner layer to the lower inner layer, the stitches being bowed or slack when the conductor segments are unenergized, the slack of the stitches allowing the upper inner layer to move rapidly away from the lower inner layer when the conductor segments are energized until the slack is exhausted and the stitches become taut, and the stitches becoming taut causing the upper inner layer to rapidly decelerate so as to shatter any ice which may have accumulated on the ice-accretion surface of the blanket.

15. A composite fabric electro-expulsive blanket as defined in claim 14, wherein the splits extend at oblique angles relative to the ice-accretion surface.