picked up a f550 kit from hobby king awhile back, have been putting it together slowly over the last couple of months, in the instructions it it states that 10" props could be used on this frame, so when i ordered all the parts I ordered 10" props, when I installed the props I found that there is only 3/8" space between the tips of the props as they swing together. That to me does not seem like enough space, what is the general rule of thumb for the spacing,? is there any? anyway have ordered some 9.5" to replace these. thanks