1. Title of the invention

Locking System for fighter and trainer aircraft canopies with mistake proofing which operates only when canopy is closed

2. Field of invention
It is a mechanical engineering design to lock the canopy safely in closed condition by positively engaging locking pins to withstand cabin pressurization load and vibration during flight.

3. Use of invention

This system is made for ensuring positive and complete locking of the canopy with a provision to prohibit the lock operation in any partially closed condition of the canopy.

4. Prior art

It was possible to operate the lock lever independent of the position of canopy. The safety features were not introduced. It was used only to just lock the canopy.

5. Draw backs of prior art

1) It was independent of the position of the canopy.
2) There was no provision ensuring that the canopy is fully closed before locking.
3) Attempt to close the canopy when locks engaged would damage the pins.
4) Mistake proofing was not present leading to doubts about safe locking.

6. Comparison between prior art and present invention
The new system has added lot of safety features to the aircraft which is useful especially for less experienced trainee pilots. With this system, locking system operation itself is prohibited if the canopy is not fully closed.

7. Aim of the invention
Aim of the invention is to eliminate the draw backs of the present practices /components.

8. Summary of the present invention

a) The locking system provides locking of the canopy in opened and closed positions both from inside and outside of the aircraft.

b) All locks designed for positive engagement and safe locking under all conditions.

c) Provision's made such that partial or unsafe locking is eliminated by introducing a simple mechanism (Stopper locking system) to prevent the Locking operation of the system when the Canopy is not fully closed. This Mechanism is unique in design ant not available in the other aircraft tested by IAF.

d) Indicators provided to directly examine the locked condition from pilot's seat.

e) Designed, such that lesser Load is applied to operate the handles for the smooth transition during the entire range of handle travel.

f) Maximum permissible load for handle operation is 35 pounds..

g) The functions of the Canopy Locking mechanism is clearly defined by the 3 Positions of the Handle.

9. Brief description of drawings

Fig-l shows the view of the locking linkage mechanism

Fig-2 shows the positions of the Handle.

Fig.-3 Shows the positive locking for the canopy with respect Handle positions.

Fig.-4. Shows the CAD Model and 2 Position sections of stopper locking system

Fig.-5. Shows the Micro Switch

Fig.-6. Shows the Physical indication of the Canopy Lock Position

10. Statement of invention

This invented locking system provides Positive locking of the canopy in opened and closed positions both from inside and outside of the aircraft while eliminating partial locking with help of Stopper Locking System.

11. Detailed description of invention
The canopy is safely locked in the closed position by five lock pins in the brackets below LH longeron which engage with slots of respective locking brackets under the canopy LH side frame. The five lock pins are interconnected by a connecting rod and in turn it is linked to two internal levers and external lever by mechanical linkages. The forward position of the internal lever is indicated as shown in Fig.-2 (and also refer Fig.3 for the Positive Locking w.r.t Handle position) canopy lock condition and the intermediate position as canopy unlock condition. The aft position of the lever is to release the canopy to close from open-lock condition. The lever will spring back to intermediate position when hand released from aft position. Pulling any one of the three levers from lock / forward position will first actuate a micro-switch (refer Fig.-5)which deflates the cabin pressure seal and then withdraw the five lock pins to unlock the canopy. The same micro-switch generates a red 'CNPY' warning caption on CWP along with audio warning. The colour indication slot on the internal lever appears fully green when the canopy is properly locked. Red colour appearing even partially indicates that canopy is not locked properly (refer Fig.6). Three spring retainers secure the lock pins in positive locked position. There is a torsion spring-loaded lever mechanism at the third lock point which prevents the locking operation of the system when canopy is not fully closed as shown in Fig.-4.

Claims

1. To facilitate locking of the canopy in opened and closed positions both from inside and outside the aircraft.

2. To provide positive locking for the canopy during flight.

3. In-built mechanism which prohibits the lock operation itself in any partially closed condition of the canopy.

4. Indication for locked / unlocked conditions of canopy.

5. To activate the counter-poise system for closing the canopy from open-locked position.

6. The mechanical system is designed for zero maintenance.