What to expect 73 skylane pponk

[182dude]

Well with my impending engine build coming up with the O470-50 what can i really expect out of my wheelpanted skylane with this engine and hartzell 82" scimitar...

Plane is under 2000hr perfectly rigged pponk tells me on the dyno these are 280-290hp engines!!

150kt?
Climb?
Fuel consumption?
Engine smoothness...ive heard these pponk are lasar smooth

Mike

[DBI]

I have that exact set-up on my 1959 C-182B. I purchased the airplane last year with everything done, it had 26 hrs on a new PPonk and hartzel scimitar. Also have a Horton STOL kit and VG's. I recently put 850's on the mains and an air glass nose fork w/ an 800 nose tire.
I have flown lots of 182's and loved all of them but this is a different animal. I live at 4750' elevation so density altitude is always an issue here in Idaho. I am usually off the ground and climbing in 500 feet or less and that is with a full load. Speeds vary depending on how much I have it screwed in but even with the big tires TAS of 125 kts are pretty easy. When I am going cross country I have it pulled back to 20" MP and about 2200 rpm and leaned out I usually run 11 - 11.75 gph.
Although I only have about 65 hours on this set-up I have zero negatives to report. The engine runs super smooth and flawless. I highly recommend it

[gear]

I have a '74P with a Texas skyways 0-520 (similar to pponk) and a hartzell 8068 82" 3 blade. It's on floats now, but when I flew it on wheels this winter ( just bought it this year) it really hauled the mail. If you want to cruise at 24 squared, if I recall, I was cruising just into the yellow.

If you search the forum, I think I posted some performance #'s and did a true airspeed test ( 3 leg method ). This was while on wheels. I included power settings, fuel consumption, egt's etc.

Garth

[Cary]

If your question is how fast will it cruise, it's still a Skylane, and so it will go faster, but not a lot. If you expect 150 knots, you'll be disappointed, but 135 or so will be doable. Your climb rate will improve markedly--that's where excess horsepower really helps.

Cary

[SixTwoLeemer]

If your question is how fast will it cruise, it's still a Skylane, and so it will go faster, but not a lot. If you expect 150 knots, you'll be disappointed, but 135 or so will be doable. Your climb rate will improve markedly--that's where excess horsepower really helps.

Cary

Hmmmm. I just flew in a stock 182 that did 135kts all day long. Hard to believe another 55 horsepower would net zero?

[lesuther]

Hard to believe another 55 horsepower would net zero?

55 extra hp nets you 7% more airspeed....that's all. Power required goes as the cube of the airspeed. So a stock ship that moves at 130 knots might gain 9 knots.

Climb power, on the other hand, is where things do better. If a 182 needs 85 HP to maintain level flight at gross, then 55 HP will net you a third more climb theoretically.

[66skylane]

I have a 66 182 with pponk and with wheel pants i would average 138-140 kts groundspeed at 21" and 2400rpms. I have owned this airplane for several years and fuel burn ranges from 13.5 to 15 gph. I now bave bigger tires and no pants and get 135kts over the ground.

[29singlespeed]

I have a 66 182 with pponk and with wheel pants i would average 138-140 kts groundspeed at 21" and 2400rpms. I have owned this airplane for several years and fuel burn ranges from 13.5 to 15 gph. I now bave bigger tires and no pants and get 135kts over the ground.

Unscientifically, it seems straight tail 182's are able to cruise at 10-11 gph at 21" and older sip more gas? I know all a factor of weight/go fast knob.

I am on the hunt for a 182 due to the current pricing and the fact most 4 place planes seem to burn around 10gph with smaller engines.

Also, pponk's seem more economical minded in cruise?

[soyAnarchisto]

Well with my impending engine build coming up with the O470-50 what can i really expect out of my wheelpanted skylane with this engine and hartzell 82" scimitar...

I'd expect a pretty big bill.

'Greg

[Glidergeek]

I have a 66 182 with pponk and with wheel pants i would average 138-140 kts ground speed at 21" and 2400rpms. I have owned this airplane for several years and fuel burn ranges from 13.5 to 15 gph. I now have bigger tires and no pants and get 135kts over the ground.

Ground speed is not a very accurate measurement . TRUE AIR SPEED is. They are two very different things. I've seen 190 mph ground speeds, only means I've got a tailwind and I've come through a mountain pass with a 60 mph ground speed means a head wind. The air mass that you travel through is a variable that you cannot control.

If you've got a GPS and most likely it's a Garmin it has an E6B function that can calculate your TAS. My 180 with 7" tires before the Pponk Trued out @ 2200rpm & 19" mp 149 mph consistently using the E6B. I saw 10.5 GPH on the fuel flow leaned 50* ROP. This was at 8500 - 9500' normally.

After Pponking, that same 2200 rpm & 19" MP, 7" wheels got me 161 TAS same altitudes and @ 50* ROP (Alcor single EGT/CHT) and 13 GPH (JPI 450 fuel flow). Then after several conversations with Steve Knopp he had me using carb heat in cruse and I use it in climb also, that trimmed my fuel flow by .5 gph, no speed penalty. No differences in engine temps.

Then I went to a JPI 700 engine monitor and have been running 2300 RPM & 19" same altitudes and able to (I think) more accurately lean to same 50* ROP and see 11.8 to 12.2 gph same TAS 160-161 mph.

i switched to 8.5" tires from 7" and lost 9-10 mph (TAS) same power settings.

[Glidergeek]

I have a 66 182 with pponk and with wheel pants i would average 138-140 kts ground speed at 21" and 2400rpms. I have owned this airplane for several years and fuel burn ranges from 13.5 to 15 gph. I now have bigger tires and no pants and get 135kts over the ground.

Ground speed is not a very accurate measurement . TRUE AIR SPEED is. They are two very different things. I've seen 190 mph ground speeds, only means I've got a tailwind and I've come through a mountain pass with a 60 mph ground speed means a head wind. The air mass that you travel through is a variable that you cannot control.

If you've got a GPS and most likely it's a Garmin it has an E6B function that can calculate your TAS. My 180 with 7" tires before the Pponk Trued out @ 2200rpm & 19" mp 149 mph consistently using the E6B. I saw 10.5 GPH on the fuel flow leaned 50* ROP. This was at 8500 - 9500' normally.

After Pponking, that same 2200 rpm & 19" MP, 7" wheels got me 161 TAS same altitudes and @ 50* ROP (Alcor single EGT/CHT) and 13 GPH (JPI 450 fuel flow). Then after several conversations with Steve Knopp he had me using carb heat in cruse and I use it in climb also, that trimmed my fuel flow by .5 gph, no speed penalty. No differences in engine temps.

Then I went to a JPI 700 engine monitor and have been running 2300 RPM & 19" same altitudes and able to (I think) more accurately lean to same 50* ROP and see 11.8 to 12.2 gph same TAS 160-161 mph.

i switched to 8.5" tires from 7" and lost 9-10 mph (TAS) same power settings.

Oh ya $30k to $40K bill easy

[66skylane]

I understand TAS is the most scientific calculation of speed however when you've owned the same airplane for several years you get to know what the AVERAGE grounsdpeed is for no wind situations.

[SixTwoLeemer]

55 extra hp nets you 7% more airspeed....that's all. Power required goes as the cube of the airspeed. So a stock ship that moves at 130 knots might gain 9 knots.

Climb power, on the other hand, is where things do better. If a 182 needs 85 HP to maintain level flight at gross, then 55 HP will net you a third more climb theoretically.

I'm with ya, done the calculations before, bought the T-shirt.

Just saying'...hard to believe one's opinion that a 285hp 182 will only do "135kts or so" all things being equal.

[Cary]

Not trying to get into any arguments, but with several hundred hours of 182 time over the years, I found that 130 knots was a pretty consistent flight plan speed, with each of them. Maybe some will go a little faster stock, depending on load, cleanliness, etc. But my point is that adding 55 hp won't make it into a speed demon; it will climb dramatically better, but it won't go lots faster; it's just too draggy an airframe.

Cary

[Rob]

..... what can i really expect out of my wheelpanted skylane with this engine and hartzell 82" scimitar...

Mike

Hard to believe another 55 horsepower would net zero?

55 extra hp nets you 7% more airspeed....that's all. Power required goes as the cube of the airspeed. So a stock ship that moves at 130 knots might gain 9 knots.

Climb power, on the other hand, is where things do better. If a 182 needs 85 HP to maintain level flight at gross, then 55 HP will net you a third more climb theoretically.

... But my point is that adding 55 hp won't make it into a speed demon; it will climb dramatically better, but it won't go lots faster; it's just too draggy an airframe.
Cary

A couple more thoughts here too....

lesuthers math almost works in a sterile perfect world... but there is normally another thing to consider, and it is one IMHO the OP should be considering...

The absolute best part of doing any big engine mod doesn't come from the HP gain.... otherwise all you gain is the 7% or whatever lesuthers quoted... the absolute best part of most big bore engine conversions comes from the new prop you are now able to turn, and that is where the majority of the Pponk / TS / whatever.. big engined guys are getting both there speed, and their climb gains....

Comparing the hp gain alone is usually not a realistic plan, because usually if you up the hp. you up the prop to take advantage of it... This is why, while a C-66 sea plane prop makes a dandy prop for a Pponk, it isn't usually the prop guys choose...

BTW, do not discount climb gains. Flying with a local 180, I routinely get to cruise altitude and leveled off (read; speeding away) as much as 10-12 minutes ahead, That's a 10-12 minute lead before we start clicking away on any speed gains...

Take care, Rob

[lesuther]

lesuthers math almost works in a sterile perfect world...

Well, those who have the extra HP get roughly the improvement I mentioned. The math is pretty simple, really.

The prop improvements are marginal, but significant. For example, the static thrust measured in engine tests can be greater with a 'better' propeller ('better' being performance rather than cost) . However, the thrust at speed offers a more marginal improvement for various reasons. If a top performing CS prop is 71% efficient at cruise, a stock prop might be 68%-69% efficient. If the old prop is 50% efficient at the beginning of takeoff, a new prop might be 53%-54% efficient. This is what the MT prop tests show:
http://www.flight-resource.com/PTD/Cessna180-182.pdf
The numbers translate into a 3-4% efficiency gain over the stock prop at static thrust. Again, it's not just the math, but real world as well. NACA's tests in the 50's showed that a simple twisted flat plate propeller design (no taper, no airfoil section, like a fan blade) could achieve around 60% efficiency at the design speed, and that an ideal propeller might achieve 78% efficiency at a single design speed. Practical propellers can achieve 70%-74% efficiency. Not bad at all! But a great propeller is an incremental improvement, not a game-changer.

You will cruise slightly faster with a new prop. You'll definitely climb faster with a new prop. A new MT is great to fly behind for its low vibration and low speed performance. You will get to altitude and start cruising faster earlier, and it will add up to just under 15 minutes' saved on a 2-hour cross country flight from 5000' to 12,000' typical in the central Rockies (cruise and climb advantages combined).

A lot of people find that attractive enough to justify the extra $18k or more for PPonk and MT. But $18k pays for a couple extra years' flying expenses for me, and the Mac is a condition inspection rather than a rebuild. It's a choice!

[gear]

Here is some performance #'s i posted on another site back in the winter.

"Took my new '74P for a 2 hour ride today. I happened to do a performance test at one set of conditions, so for those interested, here are the results. Engine is a TS 0-520F T/S and the top was done about 6 hours ago. For speed mods, i have wheel pants. Cowl flaps were closed. MP was 24", RPM was 2400. Not sure what power setting this is, but if i use the IO-520 charts, this says 69%. As I'm breaking in the top, I didnt lean to agressive, fuel flow was 19 gph. Cylinder head temps were 325, 276, 266, 269, 276, 243. EGT's were 1390, 1319, 1364, 1360, 1316, 1280. Prop is Hartzell 8068, 82" 3 blade

Altitude - 3100', 0 C (32 F), PA 3150'. Heading 270 degrees had a IAS of 168 mph, 137 mph ground speed. Heading 360 had IAS of 168 mph, 191 mph ground speed. Heading 090 degrees had an IAS of 168mph, 198 mph ground speed. According to my POH, CAS is about 166 mph and according to the E6B, using calibrated airspeed and temperature / pressure altitude, my TAS was 174 mph. According to the GPS 3 direction calculator, my TAS was 165.6 mph (144 knots), with wind at 38 mph @ 234 degrees, which was about where it was forecast to be.

So, if I have done everything correct, it would appear that my air speed indicator is reading approx. 8 mph faster than I'm actually going."

garth

[Rob]

Hi lesuther,

Thanks for filling the performance gains in terms of percentage... It is interesting.

Your cross country times and numbers seem pretty close to what I have experienced. And like you I am happry for the choices we have. I try not to assign values to other folks' flying habits, I have friends that fly C-150's and J-3's, and also friends that fly Kodiaks and Jet Rangers... Everybody's pockets are different, I am thankful I get to fly at all...

I find it fascinating that anyone would consider 'incremental propeller changes' marginal... I don't think the general masses agree, after all, companies like Catto, Prince, MT, etc, etc,,,, all depend on sales. Sales I am guessing driven by people wanting a better prop? Marginal has certainly not been my experience. Not in my play planes, and not in my work planes... In fact in my case it has almost always been a 'game changer' Here are a couple examples;

I was a part of a propeller swap on a Pponk'd C-180 recently. The same engine, plane, pilot, and weather conditions. They were actually flown within 15 minutes of each other. The measurer was a meticulous A&P / IA, who was skeptical that there would be much change. The pilot was a pro pilot, who by nature of his profession logs many, many take offs per day (should have consistency figured out by now...) No short field techniques were used, the plane was simply trimmed neutral and allowed to fly off on it's own. Both props could be coaxed into leaving the ground sooner, this technique was simply used to minimize the potential for human error...
The second prop tested, left the ground 157' sooner than the first.

I agree, that for the average person flying off a mile long paved airport, this is not a game changer. For those of us that routinely load our wives, dogs, and fishing gear in the airplanes and head to 500' - 700' sand bars for the morning, calling this a 'game changer' would be an understatement.

My work plane recently received a new prop. It is a 500 gallon plane, and at a typical muni airport it really is a 500 gallon airplane. Unfortunately, my home strip is short, and during my normal work hours the prevailing wind generally sets me up for a tail-winded departure for several hours. In these conditions this has typically turned my 500 gallon airplane into a 400 gallon airplane... It just wouldn't haul any more.
The recent prop change, was so dramatic (and the original prop was the original TC'd prop) that the airplane has now become a true 500 gallon airplane at home .
But wait... it gets weirder.. They are the same props (except as you may have figured by now the new one is 4" longer). That's not the weird part... the weird part is the new longer prop is faster at every fwd power setting.

Prop math looks easy... My opinion is that if it really were easy, ther would no longer be advancements in propellors... heck everyone would just build the best profile / length / etc... and call it good.

Take care, Rob

[lesuther]

Everybody's pockets are different, I am thankful I get to fly at all...

So am I. I think the MT gives better performance at any speed for sure...the measured static numbers and the reported climb/cruise numbers easily convince me of that.

80% of my flights are from pavement, and a Pponk/MT combo simply wouldn't be the deciding factor for the couple dozen northwest strips I visit regularly with stock wheels over the decades of work and summer fishing trips, or the handful of Utah strips closer to home here in Colorado. I would probably own a very different plane if I could live closer to enjoy some of the other strips with a slower/lower payload machine, and might not need the HP or pricey prop for that at that point.

If I had the $$, and really wanted to stretch the 182 mission as much as possible, or (my favorite) if I were as lucky as you to have a small strip out the back door ( !), I might consider it...

[aqua]

Rob,

What two propellers were tested on the mentioned PPonked C-180? And of course, which won?

Thanks,
Aqua
C-180, PPonk, C401