Jon - where do the tubes for the top (5th) engine mounting bolt connect up, I cant picture it.

Have you ever seen a photo of the Continental O-470 bed mount which Bearhawk aircraft makes?

I haven't seen a pic of the Avipro O470 mount. If you have one post it. I've looked at pics of the Maule, Cessna and Seneca mounts for ideas.

There are no top tubes going to to the 5th mount. There is just no good way to do it that will add any real strength...at least non that I can come up with.

That's interesting, I would just have assumed it was necessary, having not really thought about it in detail.
It may be worth having some firewall-flush tubes up there, just to transfer the load more evenly? Or perhaps not, I wouldn't offer any engineering opinion personally, I have no idea about the load calculations.

Without using that top hole, do you still get benefit from the V-brace struts?

I'll see if I can track down a picture - I have never seen one.

You talking about load calculations Bob used when deciding to add a 5th mount? I see what you mean about firewall flush tubes and how they would transfer the loads more evenly but I just don't think it is necessary. My main concern is the lower engine mount tubes that go from the front of the engine to the lower firewall attach point failing via buckling. Using the 5th mount and attaching it somewhere at the top of the engine would be great but the engine case was not designed for that.

Glenn P. has some pics on the bearhawk forum of his IO360 mount and it pretty much the same as mine will.

Yep - seeing as Bob is a mechanical engineer, I am sure he did the math at some point. He would have done a lot of thinking about this when designing the O-470 bed mount which Bearhawk Aircraft sells (a heavier engine than yours).

Provided there is enough weldment to transfer the bending stress to the frame, the tubes will resist bending moments and buckling via their ends. There would need to be a lot of strain for them to move enough to actually buckle? I think a cracked weldment would need to come first, via high bending stress, to precipitate a true buckle. It would be easy to add some small webs to strengthen the welds, if you felt its a considerable risk.

There will be webs at some of the weldments because I agree, cracking will likely occur before any other failure. However, because that lower tube sits at such a shallow angle it will see high compressive loads, 1000lbs at rest based on my calculations. It's critical load base on the end conditions, fixed-fixed, came out to ~5500lbs. I think I'm ok with a safety factor of 5.5 but at those stress levels I am concerned about the weldments cracking.

I'm going to give Bob a call.

Kevin wrote:....he zips through it pretty fast as he is a computer dude and I'm not so I'm lost almost immediately.....

Welcome to my world. Frigging computers anyway.

John,
Attached are pictures of my mount less the "K" or diagonal brace. I'll post the only picture I have of the Avipro mount showing the diagonal brace tube.
This picture is a bottom view of the Avipro mount

Per Bob,
I still need to add a diagonal brace from one lower firewall mount diagonal to the opposite side rear motor mount bushing.

Avipro mount cut up....verifying firewall clearance.

Hey Mark, what's the deal with that carbon fiber cowling? Is that your own homebrew?

Z, check out bearhawks with continental engines thread on the BH forum. Mark talks about it there with some pics. It is a Mooney Acclaim cowl and it looks awesome.

Thanks for posting pics Mark! I just need to finish weld my mount and add a couple small tubes for added strength. Unfortunately the Cessna exhaust will have to be modified to work because the mount is now in the way. I'll post some pics later.

I'll have to make my exhaust system. The bonanza system will not work. Three into one collectors under number 1 and 2 cylinders..... Just so I can get enough room for mufflers and heat muffs.

John,

Since you are making a mount I thought you might like to see a couple of pictures of the 0-470 conversion mount for the Stinson 108..





I have really enjoyed watching your progress on your Bearhawk..

Brian

Awesome. Thanks Brian! If I had built my mount that way I wouldn't have to modify the Cessna exhaust...but I don't want to cut my mount apart to redo it.

Untitled by Jon Whee, on Flickr

This is honestly the first time I've ever noticed how differently Continentals and Lycomings are hung. Crazy.

Not all Continentals-- the 4-bangers are hung at the aft end of the engine similar to Lyc's.

My brother showed up bearing gifts.


Pretty excited. Looking like a bunch of really nice parts and a couple extras I wasn't expecting.