Feeling the need for speed...

[whee]

My mission is changing a bit so I'm on the hunt for some speed. Recognizing the type of airplane we fly and my lower horsepower, I'm not going to go crazy. 31s are coming off and being replaced by 850x10s, I'm looking for an 82" prop to replace my 88", the spill-plate wing tips have to go, need a spinner (doubt this will do anything). Any other ideas?

My plane would do a solid 138mph TAS on 850x6 tires. That's at WOT (typically 21") and 2400rpm; 9gph. During flight testing we tried an 82" prop and it would do 147mph TAS at the same power setting. That computed because the guy we borrowed the prop from said to expect a 10mph speed difference between the 82" and the 88" prop. Now on 31s, it's 130mph TAS at the same power.

It would be really cool if we could bump 150mph TAS at that same power setting while cruising at our typical 10,000ft.

[zkelley2]

I'd go even smaller on the tires. I took my bearhawk on 8.00x6 to a lot of places. If you're landing on things that look anything like airplanes land there, that's the biggest tire I'd use.

[whee]

Two reasons I don’t want to go smaller than 850x6:

Prop clearance with my current propeller. It barely passes as legal on 850x6s and even with careful operations the prop get crewed up from sucking up debris.

The wilderness runways we have here get rutted out and pretty rough when they dry out. I flew off of them on 8.00s in my Luscombe and than was lesson enough for me to know I don’t want abuse my BH like that. 8.50s work good and it what all the commercial guys run here.

But, I already bought the 850x10 so that’s what I’ll be running for a while which will help keep my prop safe till I find a shorter one.

[rodsmith]

Just curious about the 850x10s, are you using adapters on your wheels or did you get a set of 10" wheels?

[whee]

Rod, I got a new set of wheels.

[rodsmith]

Not sure there is much else to do speed wise, other than the items you mentioned and having fairings installed everywhere. I made fairings for the top of the shock struts, doubt that will gain very much. One thought is after the other changes have someone check that your elevator position is neutral at cruise speed and adjust the incidence angle if necessary.

[whee]

Good thought on elevator position. Mine is level at my normal weights and needs some down elevator when the family is loaded up. Seems about as good as I can do.

[Nev]

That's interesting. Mine needs more down elevator when carrying rear seat pax.

[whee]

Brain cramp…thanks Nev. Down elevator for sure.

[Battson]

A spinner might reduce cooling drag?

[500AGL]

Wheel pants?
Tail stinger / wheel Fairing

[whee]

That would be some big wheel pants!

I’ve been thinking about a TW fairing. I think they look cool so might have to look for one.

[ElliotAbel]

8.50 wheel pants are pretty big. Not sure how much that will add.

[Light&Sweet]

Is it possible to add a negative, reflexive flap setting, a la Maule? Or, is the BH wing assembled in a way that doesn’t allow it?

[Chewie]

How about these, do they make much difference in speed?

https://backcountrypilot.org/images/originalphotos/125/4102/24c298a18c0c824e334415f0.jpg

[Chris In Milwaukee]

Is it possible to add a negative, reflexive flap setting, a la Maule? Or, is the BH wing assembled in a way that doesn’t allow it?

I'd pondered that in the past, but after looking at both systems including the one on my Maule, the Bearhawk flaps aren't closed loop. They use cables to pull the flaps down and springs to pull them back up. If you adjusted the "up" position of the Bearhawk flap to roughly the reflexed position of the Maule, wind speed forces would push the flap down out of that position. Maule flaps are literally pulled up and down allowing the torque tube to be turned upward. I'll need to see if I can find a mechanical diagram so we can see how it works. It's been a while since I've seen it so my memory is a little fuzzy.

[geraldmorrissey]

Guys, its a bush plane.

[whee]

I understand that perspective but I see it differently. Bob wasn't trying to design a "bush plane" when he came up with the BH. Neither was Cessna when they developed the C180. But they fit that mission quite well and with little effort. That doesn't mean they can't be set up to cruise a bit faster than average. The unofficial world's fastest C180 would cruise at just over 200mph but the owner had to work at it to get there. 150mph is achievable in my BH; small tires, smaller prop and some wing tips would get me there. I think I can get there on 25" tires...we will see.

[SpruceForest]

Look... there's guys that have those front air dams, towel-rack spoilers glued onto the hard tonneau covers over their 4.5' beds, and 50 profile tires on 18" wheels on their F-150's. I'm thinking 'dude... that's a TRUCK... go buy a purple metallic Hyundai and hang a cat-back and that other crap on it instead of the Ford.' The F-150 owner is thinking 'It's my DREAM... how cool is this?'

A seat for every butt... a butt for every seat.

But seriously... my thinking on the Patrol was that if I needed something faster and bigger, I'd rent it. Whee's thinking appears to be to squeeze out some additional efficiency from the BH to make it a more viable replacement for renting a 182 or - gasp - a Cirrus where time is a factor. I can see that. And those wheel pants? Serious Westland Lysander mojo there in the pic... and guessing that even at the size required for a good shape, there's a few mph to be had there (despite the potential PITA factor on hauling a payload of mud and gravel around inside the pant after ops on something stickier than you thought).

Some refs below...

https://ntrs.nasa.gov/citations/19930091559

https://ntrs.nasa.gov/citations/19930091591

Hoerner Fluid Dynamic Drag (should be PDF versions available online for a quick look)

[Nev]

These bad boys should save me a good 1/2 kt
(Wire cutter, profile boards and technique all courtesy of Graham Johnson.)

23869462-22CC-4B57-99F8-3AC5E135D987.jpg

8DC4E1C8-15BC-4AF9-AE5D-06609D6B83F5.jpg

219EB1C8-CE65-445C-A26C-F8AA68DA2A3A.jpg

DCDADBA4-9BF6-4D26-9420-65C27F2FD5A0.jpg

[kestrel]

Is it possible to add a negative, reflexive flap setting, a la Maule? Or, is the BH wing assembled in a way that doesn’t allow it?

It is my understanding that my original 4 place was built with reflex capability. When I bought it, the reflex had been adjusted out. I don't know the history, but someone actually flew it and decided against it.