Can wing sweep decrease total drag force at low-subsonic speeds? From  experience everybody knows if you put your arm out of car window at high speed(150km/h), it's a lot easier to hold arm angled backward then hold arm straight out(prependicular to airlfow).So conclusion will be that drag force is reduced..
Can wing sweep in same manner reduce total drag force at speeds up to 250km/h?

Pulling angled &quot;beam&quot; with rope in water will be easier than if &quot;beam&quot; is prependicular to flow.Right beam has smaller lift force but also less total drag force.Is this correct?
Sweeping back a wing of fixed spar length and area does decrease form drag. However due to both its lower aspect ratio (span/chord) and sideways flow effects, it increases induced drag and decreases lift, so that the net L/D ratio or efficiency of the wing falls.
Whether the absolute amount of drag goes up or down depends on other factors, such as wing loading and angle of incidence. In most situations drag would be higher. Where it is less, other design optimisations such as reduced spar length would offer greater improvement.