Are YOU flying a 540 in your BH?

[DesertBearhawk]

If you are flying a 540 in your 4 place I would love to talk with you. I have some questions that only a 540 operator could answer. Please either PM me or shoot me an email! Bluewingpilot@gmail.com Thanks!!!

[Battson]

Yeah, let me know if I can help.

[Helidesigner]

I have an IO-540.

[kestrel]

Why keep the discussion off-line? ...I also have a 540. -- Bearhawk

[Battson]

Fair comment Ty,

Here are my thoughts, take them for what they are (my opinion not fact):

Summary statement, if you want high performance and flexibility, but don’t mind paying, you will like the -540. If you want to be efficient, don’t need maximum performance, or want to land short as possible for toying around (when you're practically empty), you want the -360.

Fuel burn:
A subjective question to answer. Let’s say the -540 gives you more options.
You will see 90L/hr (23gal/hr) at full power.
If you want to go 130KTAS (you can only do this with a -540) that will cost you about 50L/hr (13gal/hr).
If you are happy to run Lean of Peak LOP and accept 110KTAS, then you can burn 35L/hr (9.25Gal/hr). You may need fuel injection FI.
If you are no hurry at all, you can go 100KTAS burning 28L/hr (7.4gal/hr) really LOP - this requires FI.

Useful load / CG:
These must go hand-in-hand. CG is the limiting factor. You can actually load more weight in the back with a heavy 540 in the front, because it balances better. With a small engine up there, it’s hard to use all the space in the back because you run out of balance envelope first. No point having 1300lbs useful if you can only use 800 of them. I have 1200 useful and it’s hard to find that much heavy stuff, but I can use it all (only just!!) within balance. I am regularly on the aft edge of the envelope. Having aux tanks will bring that contest between CG and weight closer to the neutral point simply by adding weight near the front. Of course this is a bad thing…

Performance:
Takeoff cannot be beaten. The -540 will impress basically anyone on take-off and climb out with a load. Cubs can take off shorter, just, if both aircraft are unloaded. But they will never match the load hauling capability.
Landings are not so great, more weight means more momentum, which is the enemy when it comes to pulling up short. I think about 300ft is the shortest most Bearhawk-competent pilots will land, and that usually means needing a 500ft space to give room for error. Adding the 540's extra po makes stopping slightly more difficult, but hitting your mark and pilots skills will always be the weak-point here. I have almost 200hrs in the last 180 days, but I cannot consistently hit a 200ft landing distance. Maybe in time.

Cost:
The -540 is a bigger engine which means it must be more costly to install and maintain, everything is larger (oil cooler, baffles, ignition harness, filters, probes, etc etc) and it takes longer to install, inspect, and test. In the distant future, the overhaul will cost more too. This is lessened with an experimental aircraft, but is still a factor. Also running a -540 without a governor is a waste in my humble opinion. The Bearhawk has a huge speed range, you cannot enjoy the full benefit of all those horses with fixed pitch – so factor another several thousand dollars in there.

Engine management:
You can’t continually mess about a big 6-cylinder like you can a 4-cylinder, unless you want it to mess your wallet about in return. A prolonged lifetime of continual power setting changes, circuits, climb-descent cycles (read thermal cycles for all the above!) will reduce the engines life during thousands of hours of operations. You can still fly it obviously, jockey the throttle when you need to. But you need to manage a big engine for what it is, the big $$ investment up the front. That demands a little more respect. You need to plan your approach further out, reduce power earlier, and generally slow the aircraft down sooner – like you do in a Skywagon, compared to a Skylark.

In the end, it all comes down to your mission.
If you want the cheap and cheerful family hauler from certified airport to airport, either a 540 or a 360 can do that, but the 360 will do it cheaper albeit less impressively.
If you want ultimate short landing performance, efficiency, or ultimate long range flight, the 360 probably has a slight advantage.
If you want to experience the full extent of Bearhawk high performance, cruise faster when you choose to, haul offensively large loads out of crazy-small places, and don’t mind paying more for all the above, the 540 wins every time.

2c - take it for what it's cost you!!

P.S. No offence intended to the very capable -360 machines, as I say, just my opinions.

[beanforge]

Thanks for that, Battson.

[mswain]

Thanks for your thoughts Battson, that is a nice perspective.

[Linusbear]

PLS allow me to share an experience which demonstrated we had the correct airplane/ engine combination (BH/540).

A group of us were flying around the desert in the CA/NV area and were landing along side a railroad siding on a gravel area about 1000' long, elevation of 1500', light winds. The Husky was the first one in and said it was OK. The Citabria was next and was fast and ground looped with a lot of dust and warned us. We landed OK and added power to get to the end. Citabria was damaged with bent wing and busted tire.

After removing the tire and securing the Citabria, we loaded the tire and his stuff, the Citabria pilot, another BH pilot, my wife and two dogs. We had less than full main tanks. We were very close to gross weight. Obviously none of this was planned but the only other option was to make two trips which was meant one more landing to a challenging strip toward nightfall. Takeoff was no problem at two notches flaps- glad I had a 540. Not many aircraft could have done this.

IMHO, Mr. Battson's comments are very accurate for those making an engine decision. If you want to exploit the full capability of the 4-place the 540 helps.

Scott Williamson
N509RF
N924PL