Domyślny zaznaczony przycisk opcji
<input type="radio" name="imgsel" value="" checked>
SteDeus
<input type="radio" name="imgsel" value="" checked>//checked
<input type="radio" id="huey" name="drone" value="huey"
checked><input type="radio" name="imgsel" value="" checked>
$(':radio:not(:checked)').attr('disabled', true);<input type="radio" name="imgsel" value="" checked="checked" />