what are the main difference between my lower tail boom...

http://www.shop.graupner.de/webapp/c...r=1081&lang=en

and this upper tail boom...

http://www.shop.graupner.de/webapp/c...r=1081&lang=en

Position mainly. Two different helis, two different looks. both serve the same purpose.

I agree that they serve the same purpose, but there is more to it. The graupner machines are designed to be used in a scale fuselage. And the Ergo, as well as most pod and boom birds are built with sport and or aerobatic type flying in mind. Indeed the standard type pod and boom can be put in a fuse. But they were not designed around that premise. A lot of scale fuselages are not well acomidated for a high set straight out tail boom. But the Graupner machines use a boom that is not only set low in the frames. But they also curve up at the end. That makes them a more viable fit for more types of scale use. Even the Vario machines, while not useing the same exact design, have the boom set lower in the frames than most pod and boom machines. Hope this helps some.