There is little loss of thrust when causing a back pressure to the exhaust of any type of pump or fan. Air or water.

Restrict the intake at all, and complete loss of pumping occurs. The intake end, always " stalls " much quicker than the exhaust end.

Edit: The air blast should push the clam doors back to the normal position. So all you need are 2 servo arms Epoxied to the clams which are mounted on a SMALL, REAL SMALL shaft. about .030" diameter. Mount the shaft in some small pieces of drilled out wood to spread the load & wear. . Then have the 2 strings tied to a seperate servo channel. It should be doable.



PM me when you have it done. [sm=thumbup.gif]