Wekusta 51 at Vannes, 2-6 June 1944

[Roundway]

I'd be grateful for advice on the approximate (or average) speed flown by the Ju 88s/Ju 188s of Wekusta 51 on weather reconnaissance sorties northwest from Vannes in early June 1944. The sorties left Vannes at about 0435 (I think that's DZT) for 49N 09 W, then 51 30N 10 30W where I think an ascent was made to about 5000 m. My reason for thinking this is that archived Met Office upper air charts for early June 1944 show data for 0500 GMT (0700 DZT) at 51 30N etc, that was definitely not made by the Irish upper air station at Valentia, or RAF met reconnaissance aircraft.

The previous year Wekusta 2 had made ascents much further north,
at 54 N 12 W, (http://www.hoelti.de/auschner/index_e.htm), and I'm hoping to confirm that in June 1944 Wekusta 51 was operating a truncated sortie.

I estimate the distance from Vannes to 51 30 N 10 30 W, via 49 N 09 W is approximately 800 km (probably slightly less). I'm aware the outbound legs appear not to have been flown at a constant altitude, with at least one descent to sea-level en route.

I'm guessing the speed was about 400 km/hour.

Any advice would be appreciated.

Brian