thinking ahead to engines -----

[NZfarmer]

Sure, PM me and I will send you some Photos

[Bissetg]

Hmmm … I know some Cub folks prefer the 160HP O320 over the O360 for reasons of weight, performance etc. If I were to build another 4B I’d go for either an IO360, IO390 or something in between. Personally I don’t like the heavy nose of a 540 for back country flying. The qualifier to that is that I don’t fly heavy loads at a high DA, if I did I would be a fan of the 540. On the other hand, if I built a 5 it would be with a 540, 550, or 580.

I reckon Fairchild could be onto a winner dependant on his mission ….

Resale … screw that. I want to build an aircraft that suits me, not someone else.

Don’t mean to be rude but ….

[Rob]

I have a O-320 I’ve been planning to use on my Patrol. For the kind of flying I do living in the Midwest I’m sure it will be fine. My 125hp Pacer does just fine, and anything I wanted to do in 17 years of owning it. A Patrol with a O-320 still has to be a performance jump over the Pacer. I had an extra O-290 125hp once and talked to Bob about it. He said a Patrol would do just fine with a 125hp engine if I wanted to use it.

[500AGL]

I’m not sure a 150/160 ho patrol would be a performance jump over a 150/160 hp pacer. It would climb better due to its wing but not sure it would be any faster.

Perfirmance is a fine balance between weight, drag, and power. A PA-11 is often referred to as the best flying cub ever built, purely from its handling qualities. It has the light weight of a J3, but you sit up front and it runs an O-200, which is a great blend of more power than a J3 in a similar fuselage. Now, a C90 powered J3 is the same animal. Fantastic performer due to the power to weight ratio.

A well flown 85 or 90 hp J3 will beat most all stock PA-18 supercubs at a stol event. It’s really really hard to beat light weight. This is why when Bob Barrows builds an airplane for himself he doesn’t bother with any frills because it adds weight. He flush rivets to eliminate drag. Everything is a conservation of energy to have a better performing aeroplane.

Like road vehicles, there are many versions of the same model. Camaros, Mustangs, Challengers, Corvettes, heck even the Jeep Cherokee can by purchased with a V6 (maybe even a 4?) or as the road blistering TrackHawk. (And if you’ve never driven a trackhawk don’t pass on an opportunity). While any number of vehicles still offer V8 power, in the pursuit of mpg many now are turbo’d 6’s and 4’s. The downfall is the loss, or hard to retain, torque numbers needed to move weight and mass. So the vehicles get lighter and smaller to help that.

in the Skiboat world everything is a V8 block because torque is king. Without anything in tow, driving a Skiboat at 30 is the same basic torque required by a car pulling a trailer uphill at 70, forever. There is no “coasting along” where you only use 25% of the available hp.
Traditional airplanes by and large are a similar animal. Take something fairly massive, and pull it fast enough through the air to not only support it, but also overcome the drag that increases four fold with every speed increase. With a little torque turned into thrust, you can go a little bit. With lots of torque and thrust, you can really get somewhere.

The Bearhawk line was designed from the ground up to be haulers. Rugged strong pickup trucks and SUV’s with the power to haul the mail. You’ll see no similarity to any of Bud Rutans designs, which are on the opposite end of the spectrum. Look at the frontal area and weight of a quickie, long-ez, etc, and you understand why it flys on 100hp or less. But then look at the runway needed to leave the ground and its climb performance. They are wonderful designs for their mission. It’s just their mission is they guy on the road bicycle that buys the “aeroshell” enclosure to streamline his drag coefficient and pedal his ass off all day to get somewhere. It’s no SUV.

Can you make a 1400lb Patrol fly with 125hp? Sure, with a long enough runway, clear approaches, you can fly just like the guy on the bicycle. Hope to hell you don’t have to avoid anything.

The fact is a Patrol is no Cub. It’s heavier, stronger, roomier, and much much faster… if you power it properly. What’s ideal right now today? Probably the newest Rotax 9xx that weighs less than a -360 and puts out 180-ish hp. The power to weight ratio is excellent.
Bobs original Patrol is likely the lightest one that would ever be built with a stock O-360, and I think that was just over 1000 lbs. Marks was 1245, and much more typical. You’re just not going to make a Patrol weigh in at sub 1000 lbs. like every J3, PA-11, most Carbon Cub SS’s. So you have to work with the airframe you have.

The range of flight parameters from a Patrol is awesome. With 180hp I can leave the ground in 200’, climb like a banshee, turn around and land back in the same space. I can fly with my cub friends at 85 mph and burn 5 gallons an hour. I can load anything I can fit in the backseat and baggage area, and cruise along at 125 mph burning 7.6-8 gph. Or I can push the levers forward and go home at 145-150 mph, on 31” bushwheels! All the while comfortable, smooth in turbulence, and fun to fly. Show me the competitors airplane than can do all that.

But my point is a Prius will pull weight if you gear it low enough. But then it won’t do anything else. I don’t drive one.

[500AGL]

Ps.
the Piper Cubs are a great machine and work excellent with their design. The J3, PA-11, PA18-90, and PA18 all benefit from a high lift wing. They were each designed as the natural outgrowth of its predecessor.
Then the world got ahold of them and started making mods, and it’s likely the most modified airframe in existence.
The 180 hp cub is an STC by those that wanted more power, and were willing to give up some of the flight characteristics of the lighter O-320 powered SuperCub. Largely popular with the float and Amphib crowd as the added drag can be a challenge.
But the cubs, like the Bearhawk line were designed for a particular power engine. The difference is cub pilots wanted to put more power on. This thread talks about putting less power on.
Want to go slower? A SuperCub is a great airplane.

[Utah-Jay]

Resale … screw that. I want to build an aircraft that suits me, not someone else.

Don’t mean to be rude but ….

Grant, you made me laugh as I am not easy to offend and you did not!

That being said your point has merit, I just look at every purchase as a commodity and potential resale value. Drives my wife nuts, but I have bought and sold flyfishing rods like crazy in the past as my casting style evolved/changes.

[Bissetg]

All good Jay, I guess my point is that having heard Nev speak so highly of Graeme’s 0320 Patrol I wouldn’t want to try and dissuade someone else from going down that path if it’s right for them.

[fairchild1934]

Wow-- this is a great thread !
My build is kind of a low budget build. ( I know that sounds contradictory when building an airplane) I acquired the o-320 attached to a pa-20.
it appeared to have been overhauled and never run. After looking at runout cores for an o-540 and also runout cores for an o-360 or io-360 being offered
at prices from 12K up to 25K $----- and then the cost to overhaul---- my all most free overhauled O-320 started looking better and better.

Having only done the wing ribs---i figure the patrol has less frontal area and a bit less empty weight---- and would be closer to happy with a 320 than a 4 place would. ( I suspect we can all agree on that--) I am not ruling out maybe finding a cont IO-360 or an O-470. They can still be found at less than sky high prices. I am looking at the o-320 as a fallback if I don't find anything I like better while the build is going on. i have no doubt that 180 or 200 hp would be ideal for the patrol. i have flown old 172's with o-300's in them---- they will not break any climb records--- but they do fly just fine.

I agree that having a short takeoff followed by a very good climb angle is what bearhawk all about ---- its reason for being. And I expect a huge anvil of a 540 on the front detracts from the good flight manners everywhere except go-arounds , quick climbs and obstacle clearing. So I expect 150-160 hp is really not efficiently juicing the orange---- but would serve as adequate. ( adequate as in the ugly girlfriend with the good attitude :-) )

NZ-farmer---- did you do anything unusual for a prop ? wood-carbon fiber or just fixed aluminum ?

Tim

[Nev]

The flight manners during go-around with an IO540 (4-place) aren't great. Due to the engine weight up front and forward CG, more aft trim is the norm on approach. When applying power for a go-around, it's accompanied by a pitch up that usually requires significant forward elevator with both hands on the stick. The easiest way to go-around safely is to apply partial power, retrim, reduce flap, then apply more power.

[NZfarmer]

Fixed pitch Catto

[500AGL]

Just for clarification a patrol would not accept a six cylinder engine so a 470/520/540 is not an option.

[fairchild1934]

500agl----- are the 6 cylinders too heavy ? I think most of them are pushing 400 lbs.
what about a continental io-360 at 210 hp ?

[Pbruce]

I like that engine too for its smoothness, but I think it’s a heavy beast. Im pretty sure it’s been used to good effect in the 4-place.

Two other considerations for the Patrol: the length of six cylinders would place that extra weight further in front of the CG perhaps leading to serious engine mount mount work and cramping of accessories. It would aldo result in more effective keel area ahead of the CofG which generally diminishes yaw stability . I’m just speculating for entertainment purposes though. I know little about these matters beyond my comments here.

[fairchild1934]

seems like weight per hP is about the same between Lycomings and conts. I think the difference is in used purchase price.

[Bcone1381]

Fairchild, I theme I see based on what you have written is the cost of the engine. Research is free and that is what you are doing with this thread.

So, consider declaring the ideal weight of the engine and prop, and tolerance of that weight in the aircraft you intend to build. An O-320 or O-360 work very well. Never seen anyone with a problem in a Patrol using them. What do they weigh? What do others weigh? Calculate the CG shift. Understand the empty weight CG envelope you desire. An engine too light or too heavy, or a mount that is too long to compensate for the lighter engine creates more problems. It seems to me like you found your engine. If you desire a more forward CG with your O-320 a metal Fixed Pitch prop will nicely accommodate your budget.

[500AGL]

As others mentioned, 6 cyl is too much weight too far forward for the CG envelope.

pb