FWF Engine Cowling

[alaskabearhawk]

Has anyone thought of doing an engine cowl independent of the firewall? Some Piper aircraft and Cessna in particular have four-point isolation mounts on the firewall and that's where the entire cowl is mounted. There are no gull-wing doors of course.

[Mark Goldberg]

Never heard of that Paul. I do not believe it has been done on a BH. Sounds like a good project to delay completion so your son can finish the plane. Mark

[alaskabearhawk]

He did talk about getting his license. Hmmmm....

[Battson]

Has anyone thought of doing an engine cowl independent of the firewall? Some Piper aircraft and Cessna in particular have four-point isolation mounts on the firewall and that's where the entire cowl is mounted. There are no gull-wing doors of course.

The Cessna cowls which use this isolation method are shaped in three dimensions so they are much stronger, and made of thicker ALCLAD than the Bearhawk cowl. They are also very expensive to replace if damaged.

The Bearhawk cowl relies on the firewall for strength because of it's simpler construction (read BH cowl is easier to make).

I am sure you could do it, you would probably need to work the cowl on an English wheel or make it from fibreglass or carbon.

[Mark Moyle]

I’m using a Mooney Acclaim cowl....someday? The plan is to not overlap the boot cowl with the engine cowl. Thinking about using a 2” wide strip of 0.050” 6061T6. Bead roller to create a step the same thickness as the combined thickness of the engine cowl and antichafe tape less the thickness of the boot cowl aluminum. The strip would be sandwiched between the firewall and boot cowl. Attached with quarter turn fasteners. Thing is I’ll have to build another tool. Can make the strip with a step...but shaping it to the differing radius of the firewall will be a challenge.. might have to make a slip roll with the correct profiles to do the job. This coming from a guy who started his Bearhawk how many years ago? Waiting on steel to build wing rotisseries for a set of stock piper short wings for my Pacer.. they’re covered through primer... will add one more coat of Superflight system 7 primer and top coat.

[davzLSA]

Hey Guys Kinda on the same subject but not, has anyone used a firewall mock up to place all the things on the fire wall and route wires and tubes before building the actual firewall, and if so was it worth the time and effort put into it?

[Bcone1381]

I have seen where some have fabricated a plexiglass mock up. I'm not there yet but will do that. I only want to drill thru stainless once. Making a pattern before I try the real thing always save me time and money.

[davzLSA]

I was thinking of just using my MDF form for my stainless firewall as a firewall mock up to lay out all the holes and locate all the parts that need to be on the fire wall and use it as a template for the actual firewall as well as the form.

[corefile]

Doing it out of aluminum would be pretty difficult - unless you happen to be in that type of business and are an expert with the english wheel - making it out of carbon fiber would be the way to go - might talk to the guys that are making the carbon fiber or fiberglass Cessna Cowling replacements - there are two companies that are making them now.

Not exactly the same things - but here is an older post about someone doing the nose bowl out of aluminum.

https://bearhawkforums.com/forum/bearhawk-4-place-plans-build/28254-tinhawk-cowling-install

[Gr8apmech]

If you were going to create glass or carbon cowling then I’d use several sheets of Home Depot Aviation Dept foam siding. Sandwich together and carve to desired shape.
You could also build a standard BH cowl and later wax and use as a form for carbon. Either way it’s going to take time.

[svyolo]

I think too much work for a one off out of carbon. Not worth it unless you want to set up to build and sell them. I might be a buyer if you do.