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[Brian Nightingale]

Treasure Coast Soaring just took delivery of another Pawnee. It's about to undergo an OBTP makeover . You're gonna love it!!

[Brian Nightingale]

Forgot this baby . When we get finished with it , It'll be a better than new Pawnee , under the expert tutelage of OBTP and Randy Opat , along with the TCS crew. Pictured are Randy Opat , club president John Eastabrook , and a couple other club members . 

On Wed, Jul 1, 2026 at 7:22 PM Brian Nightingale <aaaseptic...@gmail.com> wrote:

Treasure Coast Soaring just took delivery of another Pawnee. It's about to undergo an OBTP makeover . You're gonna love it!!

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[Charles Mampe]

Why a 6 cylinder?

More cost.

More fuel.

Not a lot of tow difference.

Keep in mind, unless a lot of tows a day, the climb saving still has the tug sitting on the ground, thus no money generation.

We run a 160HP Pawnee (cheaper spar parts) converted to 180HP(?) and look to do 1000 tows a year. We have a Super Cub for single seat glass launches midday.

Ground crew makes a huge difference getting ships turned around and off before another landing. This is a much bigger difference than 2 more cylinders. Also, "parking the glider landing" where you take off from save a ton of time.

[Mark Mocho]

160 hp or 180 hp is insufficient at Moriarty. Field elevation is 6,200 ft. MSL. Yesterday, Density altitude was 9,800 ft. And some of the fanatics out here load their gliders with enough water ballast to rival an AI Data Center. 265 hp makes for a drama-free tow. I'll happily pay a higher tow fee to avoid dangling on the string and dealing with anemic climbs in turbulent air. Between Albuquerque Soaring and Merlin Aviation, we do about 3000 to 4000 tows per year, and that is a conservative estimate.

[Kirk Stant]

Summer time in Illinois. 95F, humid (from all the corn!), 10 foot tall corn at end of 2000' grass strip, ground soft from rain the previous week, grass hasn't been mowed in a couple of days, G-103 with two average-sized 'muricans in it. And a bit of a tailwind because we are too lazy to move ops to the other end of the field.

160HP is just a bit too exciting for me! I'll take our 235 and 250 HP Pawnees any day - even our 180 Supercub struggled in those conditions.

Gas is (still, really) cheap.

Of course, I would prefer a winch, but we can't have everything (and then I wouldn't have a Pawnee to play with!).

Kirk

66

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[George Underhill]

Even at a relatively light weight of around 1,000 pounds at takeoff I much prefer a 235hp Pawnee (or 260 at high DA).   There's no replacement for displacement.

To view this discussion visit https://groups.google.com/d/msgid/rasprime/CAJ_qhM9H4M4iOTM7NxSiK4-0aXUzqV%2BC3RjdLgPu_vvcT76FRw%40mail.gmail.com.

[Matthew Scutter]

There is - and it's a turbocharger. The turbocharged 914/915/916's are turbo-normalized up to DA's over 15,000ft.

A O540 in a Pawnee makes 235hp at sea level, or ~160hp at 10,000ft, drinking ~20-30GPH.

A Rotax 916 makes 160hp at sea level, 10,000ft, and 15,000ft, drinking ~10GPH.

2000hr TBO, cheaper to overhaul/replace too.

To view this discussion visit https://groups.google.com/d/msgid/rasprime/CAHZL55eFCX7bJGc-pBnhMbn5hsULG8NVGZJnBRaWu4aDiZEMQg%40mail.gmail.com.

[Kirk Stant]

Matthew, 

Just curious, where are you located?

We don't see many (any?) "efficient" Rotax powered glider tugs in the US. Pawnees (and AVGAS) are relatively inexpensive so I'm not sure the economics of a bespoke, Rotax-powered glider tug make much sense in the US right now. In a few years, maybe?

I would love to try a modern tug. Our old Pawnees won't last forever.

What climb rate do you get behind a Rotax, towing an ASK-21 with two people, at a density altitude of 3 - 5 thousand feet? Our Pawnees consistently indicate 700fpm with the trainers, closer to 1000 fpm with dry single seaters. We are at 540 ft MSL, but it gets hot and muggy during the summertime (like right now!) and we tow off a relatively short grass field. 

Kirk

66

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[Matthew Scutter]

I have towed behind them in Europe and Australia. The 916 will tow anything a Pawnee can, at any density altitude, cheaper and quieter. Climb rates >1000fpm in a dry single. 850kg twin no problems.

The 915 is the same aloft, but a bit less takeoff thrust so slightly longer ground roll.

The 914 is single seaters only.

The other big difference is being fitted to a clean airframe rather than 1940's rags.

You can see a recent presentation about towing with them in Australia from an engineering perspective below.

https://m.youtube.com/watch?v=D9KLhAV_eUw&pp=iggCQAE%3D

It's throwing good money after bad to keep investing in Pawnees.

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[Kirk Stant]

Excellent presentation. Which actually supports both replacing the Pawnees (eventually, and field conditions permitting) and keeping them (due to high purchase cost, unfamiliar engines in the US, and short grass field in our case).

But the biggest reason for keeping the Pawnee...It's a cool airplane! Big, single seat taildragger. Unlike those wimpy little LSAs. Nose wheels and side by side seating? Blasphemy! The only thing better than a Pawnee tug is an AgCat tug!

Anyway, it's all moot - When all gliders have sustainers or are self launchers, all we will need is a winch.

Seriously, I'm going to forward your presentation to our club management to give them something to think about.

Cheers,

Kirk

66

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[Ryszard Krolikowski]

Polish tow plane Artus with Rotax 160 from Bielsko Biala tows 1.6 more than 360hp Wilga! 

Most powerful tows I ever had.

No wake behind.

Has whole wing flaperons, also negative. It has airbrakes.

Fits comfortably 2 well fed Americans

Ryszard

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[Tom Higgins]

To best answer your question “Why a six cylinder?” would be because if this airframe is serial number 2000 or higher the O-540 is the only engine you can legally install without FAA approval or STC.

Tom 

IA Seminole Lake

[Charles Mampe]

OK, I will accept that. We are at 540'MSL, so DA is not huge compared to mountains out west. Context is rather important in the US.

[George Underhill]

I watched the presentation as well as the PA 25 Pawnee Fatigue Webinar.  In the Pawnee Fatigue webinar the nominal weight for a B/C/D was 909 kg (2004 lbs) while James' calculations used a Pawnee at 1050kg.  A 141kg (311 lb) difference would certainly change the excess thrust calculation.  Perhaps the weight used for the comparison was an actual club Pawnee.  The other issue I see is the longevity of a turbocharged engine in a high-cycle up and down environment.  The water cooling helps with the shock cooling problem as mentioned, but turbo engines are inherently more highly stressed than normally aspirated ones.  As also mentioned in the video matching the use case to the tow plane is important.  On a long, hard surface, obstacle free airport the LSA would be better if you can swing the $325k USD cost.  Off a shorter grass strip at 450kg+ I'd stick with the Pawnee.

On Thu, Jul 2, 2026 at 12:37 PM Matthew Scutter <yellowp...@gmail.com> wrote:

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[Roy Bourgeois]

You wrote:

" A O540 in a Pawnee makes 235hp at sea level, or ~160hp at 10,000ft, drinking ~20-30GPH."

That is just wildly exaggerated and not at all helpful to a rational discussion.  No 0-540 (260 hp or 235) consumes 20-30 GPH at any time. 14-16 gallons per hour is more realistic.  Read the Pilot's Handbook ( which has a fuel consumption chart) - or better yet go and fly one.   Nor is anybody regularly towing at at DA or actual altitude of 10,000 feet. 

ROY

[Brian Nightingale]

I see many opinions here . Why the Pawnee ? First , we’re in Florida. It’s 95-100 degrees with 2500’ density altitude at 20’ above sea level . Second , our Pawnee weighs 520kg . I know you Europeans love your LSA’s , but our Pawnees would drag those things all over the airfield. I did some filming to see how our Pawnees performed compared to the beloved Rotax . I fly a standard cirrus and am 240 lbs . I’m airborne in five seconds from the start of the takeoff roll (at least with OBTP towing) and every video I’ve watched of your beloved LSA’s with pilots 60 lbs lighter than me takes 10-12 seconds . Another point is almost all of the glass gliders on our field have cg hooks . We have a north south runway 5 miles from the Atlantic Ocean , which means 99% of the time , we launch in a 10kt crosswind . I have aileron control in 20 ft and such rapid acceleration avoids wing drops and runway excursions. I prefer 70kts on tow , and at 95 degrees and 75% humidity we still climb at 8 kts or better . I’ve towed behind super cubs and Citabrias , and they are plain anemic compared to a 260hp Pawnee . I’ll burn a little more fuel for the added safety and performance any day . 

Sent from my iPhone

On Jul 1, 2026, at 7:27 PM, Brian Nightingale <aaaseptic...@gmail.com> wrote:



<New 540.jpeg>

[Brian Nightingale]

Also I agree with Roy . No Pawnee burns 30 gallons an hour . Our Pawnees will get me to 2000’ in 2 1/2 minutes which means even at 30 gallons an hour , it burned $6 in fuel . In reality it’s more like $3 . Your Rotax will save you $1 per tow and increases risk for both pilots . I’ll stick with the Pawnee 

Sent from my iPhone

On Jul 2, 2026, at 9:49 PM, Brian Nightingale <aaaseptic...@gmail.com> wrote:

I see many opinions here . Why the Pawnee ? First , we’re in Florida. It’s 95-100 degrees with 2500’ density altitude at 20’ above sea level . Second , our Pawnee weighs 520kg . I know you Europeans love your LSA’s , but our Pawnees would drag those things all over the airfield. I did some filming to see how our Pawnees performed compared to the beloved Rotax . I fly a standard cirrus and am 240 lbs . I’m airborne in five seconds from the start of the takeoff roll (at least with OBTP towing) and every video I’ve watched of your beloved LSA’s with pilots 60 lbs lighter than me takes 10-12 seconds . Another point is almost all of the glass gliders on our field have cg hooks . We have a north south runway 5 miles from the Atlantic Ocean , which means 99% of the time , we launch in a 10kt crosswind . I have aileron control in 20 ft and such rapid acceleration avoids wing drops and runway excursions. I prefer 70kts on tow , and at 95 degrees and 75% humidity we still climb at 8 kts or better . I’ve towed behind super cubs and Citabrias , and they are plain anemic compared to a 260hp Pawnee . I’ll burn a little more fuel for the added safety and performance any day . 

[Matthew Scutter]

It's right there in the engine manual. That's before any kind of big bore / compression mods.

There are many O540's but it would be truly extraordinary if you've found a way to make your Pawnees only use 16GPH at full throttle on a 235/260hp engine. Maybe you use 16GPH round trip on average, but that's not what I was using in the comparison above to full flow at 160HP on the Rotax. If you want to compare round trip it's even better in a Rotax because you aren't running high RPM to prevent shock cooling on the way down.

>Nor is anybody regularly towing at at DA or actual altitude of 10,000 feet.

You only have to read a few emails prior to Mark Mocho claim exactly that.

>I prefer 70kts on tow

You'll find the LSA's even better then - they don't mind the higher speeds at all.

Go and try a tow behind a 916, you'll understand it is not like Citabrias or Cubs. I have plenty of tows behind them in an Arcus & JS3.

Am I turning down a 260hp Pawnee tow? Of course not. But I've seen the club bills trying to keep these Pawnees running and they're eyewatering (or requiring exhorbitant amounts of volunteer labor). From my own club, we have a Pawnee which we recently bought, with an engine that now needs an overhaul less than a third of the way through TBO, it then needed new spars, and next likely a new rudder. The totals on that are about the same as a new Eurofox 916, with a warranty, actual capital value, cheaper annuals, lower overhauls, lower fuel consumption. Alas.

To view this discussion visit https://groups.google.com/d/msgid/rasprime/D22B4169-05B6-45BF-9ED5-F8AF42A583BA%40gmail.com.

[Roy Bourgeois]

The chart provided does not support the claim that an 0-540 consumes "20-30 GPM" under any realistic circumstances. Indeed,  the vertical axis of the chart peaks at 26 and the data lines go nowhere near it. A gliding club can expect 14-16 GPH from a Pawnee 235 or 260 - or about 1.8 to 2 hours towing off the 36 gallon tanks ( with safe reserve).  There may be reasons to use a Rotax powered towplane,  but the argument should not require exaggeration of fuel burn.

I  currently tow several days a month with 2 different 0-540 Pawnees, I own one,  have flown 10 different one,   and refueled them all. I spend half of my year flying in the USA and the other half in South Africa where fuel is more expensive and my club has both a Rotax powered and an 0-540 powered towplane.  Guess which one everybody lines up behind?

Towplane selection for any club is complex and requires a weighing of several factors including initial acquisition cost, operating costs,  engine TBO vs TBR ( an issue with some Rotax engines),  familiarity of mechanics with the type,  availability of parts,   tow pilot training and experience with type,  weight of gliders towed vs.  towplane weight and inertia (important for students learning the tow),  experience of glider tow pilots, takeoff runway surface, and typical density altitude to name a just few of the factors. Depending on how you weigh those factors you can make an argument for almost anything.

Every glider club confronts these factors differently and their decisions should be respected. 

ROY