Hi Flyboyj,
>From East block aircraft I've seen really up close or worked on (Mig-15, 17, 19, 21, 23, L-29, L-39, TS-11) I've never seen any arrestor system - No need for arrestor systems on dirt runways, the same way the take off distance is usually and additional 10%, landing distance is usually reduced 10% on dirt strips for most aircraft....
The GDR at least developed arrestor systems for the MiGs and Sukhois they were using, but these were of the barrier type and did not require special equipment on the aircraft.
One variant of the system was mobile and could be deployed anywhere at short notice, but I don't know if they ever used it for dirt strips.
The barrier was normally lowered so it wouldn't interfere with flight operations, but could be raised in a couple of seconds. In the early variants it was activated by the tower (normally upon request by the pilot), but the later variants seem to have been triggered when a photocell registered that the beam of light aimed at it across the runway was interrupted. (Grr, what's the English term for that type of sensor? Couldn't find it!)
I assume photocell-triggering had to be armed by the tower too, or the system wouldn't have become as "MiG catcher" as it was historically, but as "deer catcher"!
Regards,
Henning (HoHun)