Bill : The bending moment and axial loads you mentioned. Could it possible be - why some of the early design allumnium casted sumps, of the Mistral 3 rotary engines developed cracks ? as i remembered that the bed type mount for the rotary ( pusher type config.) the thicker sump and plate, has a lot to do with these loads and stiffen the rotars and irons as a solid unit, as well the bigger diameter tension bolts and “dowls”
It was just crossing my mind, and i have no previous experience in these loads and type of mounts as well as the casted sumps.The torque loads of the prop and all ads up.
Included : cut out of the article Mistral Magic Could the loads be part of the sump problem in these type of mounts? i don’t know.
Cracked Sump “I did have a couple of teething problems; the most important one was a crack in the aluminum-cast engine sump that I found during taxi tests. Mistral reacted in their usual fashion. After getting details, they confirmed they had a crack in the same area on one of the sumps they tested. They designed a reinforced sump, but never got a repeat crack on the other sumps, so none of the new models were made. I was offered a temporary replacement until the new sumps would be produced to replace all present sumps. I decided to wait, and got my new sump within two months—and a Mistral engineer came and installed it for me.”
Sent from my iPhone Le Roux Breytenbach On 03 Aug 2020, at 19:34, William Jepson wrjjrs@gmail.com <flyrotary@lancaironline.net> wrote:
Charlie, and everyone rotary, I can see the desire to put a rotary in a similar mount to a standard aircraft engine. But I want to remind everyone that a Mazda wankel in its automotive layout doesn’t work well as the stack of plates and housings isn’t set up to handle the bending moment. In Mazda’s racing engines they added plates to enable them to hang the engine from one end. They still used cradle mounts. The Lyc engine shown in the example has 2 crankcase halves solid front to rear where the mounts are. If you don’t plan to build the rotary with some modifications for axial stiffness and housing location it isn’t a good idea to hang it from one of the end plates. Bill Jepson
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