Gottlob Espenlaub
... that German aircraft designer Gottlob Espenlaub began testing his rocket-propelled gliders in as early as 1929?
... that German <a href="./Aerospace_engineering" id="mwFrg" rel="mw:WikiLink" title="Aerospace engineering">aircraft designer</a> <b id="mwFrk"><a href="./Gottlob_Espenlaub" id="mwFro" rel="mw:WikiLink" title="Gottlob Espenlaub">Gottlob Espenlaub</a></b> began testing his <a class="mw-redirect" href="./Rocket_glider" id="mwFrs" rel="mw:WikiLink" title="Rocket glider">rocket-propelled gliders</a> in as early as 1929?