> > Hi, > I am almost in the position to order my gearbox. The gearbox is in direct > link with the proppelor and rpm, so I need to make a dissision for the > diameter. Now is my question wat is the max diameter I can use on the KR2-s. > I do not mean the ground clearance, but I am affraid that the giroscopic > force wil brake off the fire all if you use for example a 65 inch dimeter > prop. > Or is everybody laughting to me and say that I dont have to be affraid for > that. > Engine is a BMW 1200 110 hp. > Thanks you all > stef > > -- > > Steph and his dad are building the KR-2S see > http://www.masttotaalconcept.nl/kr2
Stef, I sincerely hope your fears are unfounded. There are two reasons for the short props you see on KRs. Ground clearance and the prop RPM for the direct drive VW, Corvair and Jabiru engines. For the rest or the engines that turn a slower RPMs at the prop (Continental, Lycoming, Rotax, geared VWs, & most other geared engines) a longer prop is desirable if the plane has the ground clearance to turn it. The ideal prop for an O-200 is 72" diameter, but I don't know of any KRs that have long enough legs to use it. If I could, I would. Mine is one of the longer legged KRs. I don't recall for sure now, but I believe my current prop is either 66 or 68" diameter. -Jeff Scott Los Alamos, NM
