GB2281219A

GB2281219A - Improvements in retracting undercarriage systems for model aircraft

Info

Publication number: GB2281219A
Application number: GB9317957A
Authority: GB
Inventors: Anthony John Goodger
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-08-28
Filing date: 1993-08-28
Publication date: 1995-03-01
Anticipated expiration: 2013-08-28
Also published as: GB2281219B; GB9317957D0

Abstract

An improved undercarriage system for model aircraft comprises a "Y" block of particular geometry (figure 1) which when pivoted in conjunction with an adjustable stop (B) provides both a variable retraction angle and positive down locking. Where the mechanism is pneumatically or hydraulically operated, an adjustable valve (figure 2) incorporated with the flow/return to the power cylinder is used to control the speed of operation which is not only advantageous, but is also necessary to prevent overrun, jamming and consequent damage to the mechanism (figure 3). The block is pivoted by means of a horizontally moving cross pin C, so that the further the pin travels across the angled face (A, Figure 1), the greater the retraction angle. <IMAGE>

Description

IMPROVEMENTS IN RETRACTING UNDERCR GE SYSTEMS FOR MODEL AIRCRAFT This invention relates to improvements in and relating to retracting undercarriage mechanisms used for model aircraft.

A variety of mechanisms are used to retract undercarriage legs in model aircraft and these may be powered electrically by means of a screwjack or coupled servo, pneumatically or hydraulically. One of the most common mechanisms used is the "Y" block operated pneumatically which is offered with a set retraction angle Cusually 9fly3 and no means of inbuilt speed control for the pneumatic cylinder. Most model aircraft, particularly scale replicas, require different retraction angles and the speed governed to give realistic operation.

Another essential feature provided by the "V" block is positive up and down locking.

According to the present invention a "V" block of particular geometry operating in conjunction with an adjustable stop provides both a variable retraction angle and positive down locking. Where the mechanism is pneumatically or hydraulically operated, an adjustable valve incorporated within the flowXreturn to the power cylinder is used to control the speed of operation which is not only advantageous, but is also necessary to prevent overrun, jamming and consequent damage to this mechanism.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows the "Y" block with new geometry and adjustable stop; Figure 2 illustrates a typical adjustable speed control valve incorporated within the power cylinder end plate;and Figure 3 shows the above features incorporated in to a pneumatic retracting undercarriage mechanism to give an adjustable retraction angle with controlled speed of operation.

The important feature of the "V" block is the angled face, labelled A, in figure 1 which in conjunction with the adjustable stop, labelled 5, allows setting of the retraction angle. The block is pivoted by means of a horizontally moving cross pin, (as shown in figure 3, labelled W,the further the pin travels across the angled face, the greater the retraction angle. The cross pin is supported against vertical movement by either slots in the side plates or a fixed support above it. Face angles may be between 100 and 350, but an angle of 250 is found to be most convenient as, at controlled speed, it locks without jamming and in a typical retract design will give a retraction angle range of 850 to 95 . Where the height only of the angled face is raised or lowered in relation to the pivot position, the ranee of retracting angles attainable may be altered.

A typical arrangement of the adjustable speed control valve is shown in figure 2. Fluid enters and leaves via the connection, labelled D,and is then channelled to the adjustable needle, labelled E, which controls flow into the cylinder at position F.

Claims

1 A retracting undercarriage mechanism for model aircraft containing a "Y" block of particular geometry operating in conjunction with an adjustable stop to provide a variable retraction angle together with positive down locking.

2 A retracting mechanism as described in Claim 1 when operated pneumatically or hydraulically containing an inbuilt variable flow control valve which is advantageous to limit speed and necessary to prevent overrun, jamming and consequent damage to the mechanism.