Making an alteration to my cowl.

[EdFred]

The Cherokee cowl seems to be a big bowl - at least the top of it does. It catches all the air coming across the top of the cylinders but it doesn't really flow out anywhere. It just sort of sits there and presumably slows the plane down. (Shut up Anthony ) It would seem like a very simple modification to cut slots in the sides of the cowl and allow an outflow from the engine compartment. Of course on the inside there would be air scoops to guide that air coming in off the tops of the cylinders and guide it out efficiently. Obviously a 337 is in order, but would this also require an STC which I would have to obtain?

Not that I am going to do it, just thinking about it.

 

[Let'sgoflying!]

What problem are you addressing, Ed?

Modifications can be made without an STC; you will have to get with your FSDO on how to go about it. (drawings, description and approval before the first cut is made!) I bet you will need some engineering studies to back up any plan like this. It will become hugely expensive.

 

[Ed Guthrie]

The Cherokee cowl seems to be a big bowl - at least the top of it does. It catches all the air coming across the top of the cylinders but it doesn't really flow out anywhere.

Airflow within the cowl is in the top (high pressure ram air), downward through the cylinder cooling fins, and then out the bottom (low pressure slip stream air). If you vent the upper half of the cowl into the slip stream you will destroy the cooling flow within the cowl.

 

[ggroves]

It just sort of sits there and presumably slows the plane down.

Your wings are bolted on too low, too....

I'm guessing you would radically change the air cooling dynamics....

Have you checked on anything from LoPresti, et al for available mods that have been tested and have an STC?

Greg
182RG

 

[EdFred]

I thought about that Ed. I just though that the air slamming into the firewall wasn't the most efficient way of getting the air out of the cowl.

 

[EdFred]

Your wings are bolted on too low, too....

I'm guessing you would radically change the air cooling dynamics....

Have you checked on anything from LoPresti, et al for available mods that have been tested and have an STC?

Greg
182RG

Nobody seems to make any mods for the front end of the 180. No 200hp STC, no LoPresti Cowl, no Powerflow exhaust. Nada. Not that I have seen anyway.

 

[Skip Miller]

I thought about that Ed. I just though that the air slamming into the firewall wasn't the most efficient way of getting the air out of the cowl.

The baffling should direct most of it down through the cylinder fins.

-Skip

 

[Bill]

Nobody seems to make any mods for the front end of the 180. No 200hp STC, no LoPresti Cowl, no Powerflow exhaust. Nada. Not that I have seen anyway.

You want a faster, more capable plane, but seem to be inventing interesting sidestep maneuvers to avoid the obvious...

 

[Ken Ibold]

You want a faster, more capable plane, but seem to be inventing interesting sidestep maneuvers to avoid the obvious...

Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney.

 

[Bill]

Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney.

55 Mooneys can't be wrong, but a Skylane might not be a bad choise for Ed. He wants more speed and capability, but still requries short field / grass field operation. Sounds like a Skylane or similar to me.

 

[EdFred]

2 more cylinders = more fuel burn. That's bad.

 

[Bill]

2 more cylinders = more fuel burn. That's bad.

Yup, the club 182 burns 14gph leaned at 6k. But, it does fly fairly fast (140 true) and gets up off the runway quick.

Personally, for a number of reasons, the Diamond DA40 looks good to me, but even used ones are too spendy for me.

Still, I'm having trouble finding a good plane for your mission. The faster 4cyl planes (Tiger, Mooney, etc.) just aren't suited for short/soft field ops. For higher speed AND short/soft, all indicators point to 6cyl planes.

 

[EdFred]

You want a faster, more capable plane, but seem to be inventing interesting sidestep maneuvers to avoid the obvious...

My plane is like a decent but not great poker hand while playing limit hold em. I'm already in the pot (430, speed mods, other goodies), just gotta ride it to the end. Besides, even if I had a mooney at 175kts, I'd still want another 30 knots at 10gph, and still get in and out of a 2300 grass in July.

 

[Joe B]

I thought about that Ed. I just though that the air slamming into the firewall wasn't the most efficient way of getting the air out of the cowl.

It slams into the firewall?? Most Cherokees I've seen have baffling across the back of the engine which keeps the air from getting any further, forcing it down throught the cylinder fins. There's usually a strategic hole or two in the baffling to direct cooling air at mags or other accessories. The Cherokees I've seen without this baffling have all been in the shop...

Granted, the combination of cowl, baffling, cylinder fins, and other stuff in the engine compartment doesn't exactly make for a streamlined flow of air through there. But (speculating) I'll bet there's a big difference between the cooling ability of a streamlined airstream vs. a turbulent one. If so a streamlined engine compartment would require a larger cooling area (ie: bigger cylinder fins) to work. TAANSTAFL.

Regards,
Joe

 

[Graueradler]

Mods generally reduce the size of the entry openings to reduce the amount of air entering the cowl. Also look at Art Mattsons cowl mod (pipermods.com) that he developed in conjunction with an exhaust system mod. It starts slanting back immediately below the prop instead of continuing down to below the light.

http://www.pipermods.com/newcowl-exhaust.htm

 

[AirBaker]

Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney.

Or...

Money Money Money Money...

It seems to me that unless you really know what is going on in the cowling, cutting holes would be a bad idea. Sometimes letting a little air through is worse than no air through at all. That said, I do not have my degree in fluid mechanics.

I'd rather develop a ram air scoop for some better forced induction at speed.

If we were talking about the testing performance on an old beater, airport car, I'd tinker all day long.

 

[ScottM]

It slams into the firewall?? Most Cherokees I've seen have baffling across the back of the engine which keeps the air from getting any further, forcing it down throught the cylinder fins.

I was wondering the same thing. I have a PA28-161 and the baffling is such that air comes in the front, accross the top of the cylinders and then down through the cylinders. No way for it to slam into the firewall.

 

[Stache]

Any changed to the cooling of the engine would/will require a one-time STC. The FSDO Inspector is not allowed to Field Approve changes to cooling. Reference FAA Order 8300.10 Vol. 2, Chapter 1 covers this.

Stache

 

[flyingcheesehead]

Yup, the club 182 burns 14gph leaned at 6k. But, it does fly fairly fast (140 true) and gets up off the runway quick.

14 gph? That seems high. I flight-plan 13 gph in our 182, and the average fuel burn on it for all of 2005 was 12.79 gallons per tach hour. (Being club treasurer, I can be a number geek. ) I generally fly it at 6-10K on trips, FT (21-23" or so)/2200. Of course, I only plan on 130 true.

Ed F, you need to read this:

http://www.avweb.com/news/columns/188945-1.html

 

[Bill]

14 gph? That seems high. I flight-plan 13 gph in our 182,

Well, to be honest, the gauge was reading about 13.7 (to be a number geek ), but I rounded up. I'd bet that .7 difference is in the noise of the gauge.

 

[bharris]

I thought about that Ed. I just though that the air slamming into the firewall wasn't the most efficient way of getting the air out of the cowl.

If your baffles are correctly installed, the air is forced through the cooling fins around the cylinders and then goes out the bottom of the engine compartment. There should be very little air "hitting" the firewall.

 

[Iceman]

The air is slamming into the top of the cowling. This slightly pressurizes the air above the cylinders and then it blows down past the cylinders. If you cut the cowling the air will find the path to least resistance and flow out the plane without cooling the engine.

Gas is not necessarily related to number of cylinders. Just last weekend the mooney made it back from Sedona, AZ to Kalamazoo, MI with no stops and fuel left over for another 1.75 hours.

 

[AirBaker]

1300NM? Thats a pretty darn impressive range.

 

[bbchien]

Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney, Mooney.

I am looking at the Aircraft Spruce trophy 1993 third place tropy for PSP-->DPA at an average of 179.8 kts nonstop, 1400 nm in the middle of summer, not much tailwind. Mooney, Mooney, Mooney. Did it on 90 gallons in an M20J

 

[AirBaker]

I am looking at the Aircraft Spruce trophy 1993 third place tropy for PSP-->DPA at an average of 179.8 kts nonstop, 1400 nm in the middle of summer, not much tailwind. Mooney, Mooney, Mooney. Did it on 90 gallons in an M20J

Impressive.

Ice, you only had another 100nm or so to go and you could have said you've beaten that record for mileage.

 

[Iceman]

I think steve b ? did ~1700 nm in a columbia 300 around a year ago... That's a long time to spend in an aircraft.

Long distance flying try this site http://www.kerrlake.com/mgarratt/pilot.htm

 

[Steve]

If you want to go for distance, go experimental...

http://www.southern-aviator.com/editorial/articledetail.lasso?-token.key=1850&-token.src=column&-nothing

 

[Bill]

If you want to go for distance, go experimental...

Steve, is your bird considered experimental?

 

[Steve]

Yes - Experimental/Exhibition, but since I'm not the "repairman of record" I still need an IA to sign off the annual "condition inspection", which is why I have him involved in any maintenance I do or have an A&P "tech" perform.

EAA/Warbirds of America are pressing the FAA to eliminate some of the unfounded operating limitations on "warbirds" in this category (virtually all foreign built and a majority of the domestic "heavy iron") which do nothing but violate the paperwork reduction act. There are promises to have them removed by OSH '06. We shall see.

A couple of examples -

Notify local FSDO if you plan to fly beyond your "proficiency area" (300 nm radius for piston under 800 hp, 600 nm for 800 hp and higher ). You don't need their permission or even acknowledgment that they received the notification, you just have to submit the letter.

Turbine/Turboprops - Notify local FSDO if you plan to land at an airport other than the one where the aircraft is based.

Basically you submit an annual "letter of operation" listing the events you intend exhibit the aircraft, which can be amended at any time to add new events.

I could be violated for going 301nm as it now stands if I didn't notifiy the FSDO beforehand. It does make me feel much safer knowing that the FSDO knows that I know that they know where I'm flying. The wing could fall off if you fly too far afield without proper federal documentation, you know.

Steve, is your bird considered experimental?

 

[Bill]

The wing could fall off if you fly too far afield without proper federal documentation, you know.

Just like planes falling out of the sky for not filing flight plans...

 

[ScottM]

Just like planes falling out of the sky for not filing flight plans...

I don't think they fall out of the sky due to that but it is clear that the pilot is a reckless sort for not filing a VFR flight plane for his 30 minute flight to fuel