IO-580 Cost

[Utah-Jay]

Limited to 8,000’ for full power it seems

[Gerhard Rieger]

I also wanted to use a Auto engin, Lexus V8, Burt Rutan did a concept aircraft for Toyota with the lexus engin, but I found the amount of effort and cost involved with design risks is not worth it. I spend many hrs reading up and looking at different setups, at the end I followed Bob good advice and bought me a IO 540. But we are still experimental and in the spirit of that thought everything is possible.

[Brian Mason]

Is anyone seriously considering the AC Aero liquid cooled IO540 conversion? That is the engine I'm considering for our 5. Larger bore 300+ hp

[triumphantduke]

I’ve got my eye on it… but waiting for some customer proof of success

[Brian Mason]

Dont wait for me to get one, LOL, I'm a couple of years away from that point. Hopefully, someone will get one, and a Higgs diesel, too.

[Alan]

I believe the bull moose is running an Auto PSRU that they acquired the rights to build.I’ve heard they have issues with the prop shaft breaking under gyroscopic forces during aerobatics. The bear hawk isn’t going to be creating the extreme levels of gyroscopic forces in order to break the shaft. Or so I would think.... the stinger drives ls3 PSRU is only $5300.

[Rudder]

I believe the bull moose is running an Auto PSRU that they acquired the rights to build.I’ve heard they have issues with the prop shaft breaking under gyroscopic forces during aerobatics. The bear hawk isn’t going to be creating the extreme levels of gyroscopic forces in order to break the shaft. Or so I would think.... the stinger drives ls3 PSRU is only $5300.

Mahhh just have AC build you a stroker engine if you want a car engine go with their water cooled cylinders and a efi system. Most people don’t think about the high revs and harmonics but that’s the killer for me and auto engines. I think their 0-360 based stroker 409 with efi and a cold air intake it at the same HP as a IO-540. https://www.ac-aero.com/legion-kits/

[Brian Mason]

What worries me about that is your 360 conversion might weigh significantly less than a 6 cyl and render your useful load envelope too narrow so you might have difficulty being able to put 4 full sized adults into seats, much less cargo.

[esroths]

If I ever build a model 5 I would strongly consider looking for a used Cont IO-550R 310hp. It's a great engine and you can probably get them used and send them to Lycon for performance OH for about half of a new IO-580. Just saying...

[Rudder]

Don’t be like that just put a transfer fuel tank back there. Also a better option than the removable weights in the prototype. Fuel transfer out when people cargo is back there transfer in when empty from the main wing. Experimental brother.

[PaulSA]

To be honest, I think the 5 would have ample power with a standard 260hp Lycoming IO540. Thunderbolt it or get an Aerosport port and flowed, PMags and you've probably got 270, 280 or so ....

[zkelley2]

To be honest, I think the 5 would have ample power with a standard 260hp Lycoming IO540. Thunderbolt it or get an Aerosport port and flowed, PMags and you've probably got 270, 280 or so ....

Not for any kind of short field ops. The bearhawk needs the power to weight ratio to be high, it's what makes it a back country performer. To keep the same power to weight ratio as the 260hp 4 place, you need 312HP. You'd probably need a touch more to get the same performance, since the speed at which the 5 will start flying will be higher as well.

[zkelley2]

I'm talking gross weights, since those would presumably be the same for everyone.

At 9.6lbs/hp at gross the bearhawk 4pl has, I think, the highest power to weight ratio of an aircraft in it's class.

[jaredyates]

I like your line of thinking Zach though I think if I owned one I would probably not have an apples to apples gross weight usage. We had a hard time hitting 2500 on our 4-place before bulking out, and I could imagine a similar scenario with the 5. It would be nice to have the 3000 maximum, but I don't know how often we'd use it.

[zkelley2]

Full Aux tanks and 4 people and I'm gross and in CG. Being able to do that plus bring gear sure would be nice. That's what the 5 is for. 4 people and things. Just like any 4 place aircraft is for 2(maybe a light 3rd) and things.

Just like a 360 powered 4 place doesn't have the acceleration to operate out of short stuff, a 260hp 5 won't either.
If you're flying to 1500+ft runways and are ok with anemic 172 like performance I'm sure it'd be fine.

If I were building a 5, I'm fairly sure it'd have an angle valve 540. I'd probably explore a 720 or a 550 before the 580 personally. There's a lot of good aftermarket for the 550 that comes out of the racing stuff.

720... extend the wings a bay, get some slats on there, slotted flaps and you've got a helio!

[PaulSA]

OK, perhaps I should have said that for a lot of people, most of the time, 260hp would be sufficient. Not everyone wants to go taking off and landing in river beds! I operate my 2700lb gross, 260hp RV-10 out of a 1800' grass strip normally around 5000' DA just fine - and that has stubby little high speed wings.

I'm building my Bravo with an Aerosport IO375 @200hp and a 3-blade MT prop. I have 6x8 mains and a 10" tailwheel. That'll take me anywhere that I want to/need to go. So, yes, for my needs, a 260hp BH5 would be awesome - I just don't think I have another build in me!

[Nev]

I think you’ll get the very best balance between takeoff and landing distance with that engine.

[zkelley2]

Ha! If I could operate with 6's and that kind of runway requirement, I would have built an rv10 instead.

I abhor all the speed penalties landing short requires. If I didn't need them, I wouldn't look anywhere near a stol airplane.
I hate my 31's and the speed penalty they give. It's why I try to dissuade people that really don't need bushwheels from buying them. It's the dumbest thing ever. I so wish I could put my 8.00's back on and get my 15-20kts back.

[rodsmith]

I could go on quite a rant about big tires and the people that think they need them. Wish I had better pictures of the places I went with a Maule on 8.50s. A couple friends put 31s on their Zenith 750s and don't go anywhere that would concern me with 8s or even 7s.

[Rudder]

Good insight on the tire sizes. I’m not building a motorcycle I’m building a plane.