Radar elevation control considerations "tips"

[IvanK]

Here is my take on making Antenna elevation control in the MIG29 in a Free search (no GCI) environment manageable. I fly in Imperial so I have used nm and feet for the discussion. The Target Manual range throttle wheel was not operational in this version of the MIG29

Situation:

TDC position in range coupled with Delta H selection controls Antenna elevation and therefore the altitude coverage. With a Fixed Delta H changing the TDC position in range causes the Antenna elevation to change. So as you move the TDC over the target Antenna elevation will change, at close ranges this antenna elevation can be large.

Radar Information

In search the 4 Bar scan covers on average 10 degrees. The coverage does in fact vary depending on function and TDC range position but 10 degrees is a good calculation compromise. Each click of Delta H varies the beam centre Altitude coverage by 1000m or 3280' for the +- 1 Delta H click. For the remainder Delta H clicks 2, 4, 6, 8 each click raises the antenna 2 degrees or 2000m or 6400’.

Proposed solution:

To minimise pilot workload and keep elevation control workable I suggest placing the TDC at 30nm range. This is a typical contact range in the Mig29. It also means that small TDC changes in TDC range to place it over the target will not result in large changes in Antenna elevation. As can be seen in the diagram below 10 degrees covers a fair bit of sky 32,000' at 30nm and 64,000' at 60nm.

With the TDC at 30nm the AH value effectively equates to antenna elevation in degrees.

(The old Elevation formula: Ant Elev = Alt Diff in 100s ft/Range in nm might be handy)

If running at sea level then to get the bottom of the beam close to parallel to the ground then set TDC at 30nm and delta H at +4.  (2 clicks of Delta H = 4degrees in elevation). Which means at 30nm you are covering Ground level to 29,000’ and at 60nm ground level to 58,000’.

Once you have the search process done then consider going into TWS as Antenna elevation will be controlled by the FCS.

With Good GCI then the TDC can be placed at the called target range and Delta H value.

[YoYo]

Thanks for the explanation! 
I'd also like to request an axis that would work incrementally for elevation:

 

[AeriaGloria]

An axis working -6/-4/-2/-1/0/1/2/4/6/8/10? Ten positions?

[primus_TR]

5 hours ago, AeriaGloria said:

An axis working -6/-4/-2/-1/0/1/2/4/6/8/10? Ten positions?

Question: Even when the HUD is imperial and/or the altimeter is indicated in feet, these numbers still represent dH in thousands of METERS, not thousands of FEET, correct? 

Edited 7 hours ago by primus_TR
clarity

[IvanK]

Delta H is in metres hardwired as far as I am aware. In my notes I have converted to feet for the calcs.

also another calc if down in the weeds and want the bottom of the beam on the horizon (i.e. at ground level) you need 5 deg ant elev you can get that 5 deg by:

TDC 24nm Delta H +4

TDC 37nm Delta H +6

Edited 33 minutes ago by IvanK