instantaneous VSI

[spare]

recently i obtained a instantaneous VSI as a souvenier. it was formerly from a B747. While i think i understand how an ordinary VSI works , how does an "instantaneous" one differ mechanically? I have heard that it has accelerometers ? is that true ...are they weights or electrical. The unit i have is from aerosonic i think.

[balti king]

You're right - It does contain an accelerometer. This creates a quicker reaction to differential pressure than the conventional VSI. The accelerometer consists of a dashpot (pistons held in balance by springs) and is connected to the static capsule via a capillary tube. A change in vertical acceleration creates movement in the dashpot and thus alters the pressure in the capsule immediately creating pointer movement. As dashpot response decays the "actual" pressure change in the capsule becomes effective and the IVSI acts more conventionally.

I hope this answers your query.

BaltiKing

[This message has been edited by balti king (edited 16 December 2000).]

[This message has been edited by balti king (edited 16 December 2000).]

[spare]

thank you very much ...now i've understood.the instantaneous part is for the needle to show up or down quickly ...is it ? but the over all accuracy will not be affected . am i right ?

prasanna

[CONES R US]

the accuracy is not affected by the accelerometer, it is just there to make the reading more accurate for small deviations, hence the name instantaneous vsi.

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