Towing with a Pawnee 150
Wallace Berry
tug? We currently tow with a Cessna 175 that has been re-engined with an
O-360 and equipped with a STOL kit. It is an OK tug off a 5000' paved
strip but not great. I've been towed by a 180 hp Pawnee (Jeff Cloud) and
find that to be an excellent towplane.
We are buying a low time Pawnee currently equipped with a low time 150
hp engine. We hope it will tow at least as well as the C-175. If so, we
will keep it and eventually re-engine it to 180 hp.
Thanks,
Wally
Stewart Kissel
information?
MHende6388
We have towed with a 235 hp Pawnee at our 2,000 MSL strip and 1200 lb gliders.
Perfect workhorse.
Would not us a 150 hp Pawnee or anything 150 hp here especially when it gets
hot. The negative trade-offs are too severe.
As a matter of fact, our second towplane is going to the a 260 Pawnee.
Good luck.
Michael
Wallace Berry
Stewart Kissel <REMOVE_TO_REPL...@hotmail.com> wrote:
> Altitude of airport and summer temperature/humidity
> information?
>
>
>
We are located in the southeastern U.S., LaGrange, Georgia and vicinity.
Altitude is 700 feet msl. Summer temps are usually mid-80's to high 90's
and humidity around 50% during the day. Our usual runway is 5000 feet.
Stewart Kissel
in Colorado Pawnees come in two flavors-260hp or 235hp.
However don't be surprised to see the baby birds open
their mouths when you fly low over their nests behind
your 150 Pawnee, and you might be able to generate
revenue by billing the local farmer for fence inspections
from the air.
At 16:24 12 May 2003, Wallace Berry wrote:
Mike Borgelt
The 150HP Pawnee is very marginal as a towplane even near sea level.
That engine works better in a Cessna 150 as a towplane or a C150 with
180 HP is a GREAT towplane. I've watched one beat a 235 Pawnee towing
similar gliders and you have only 2/3 the fuel costs.
Mike Borgelt
Michael
> tug? We currently tow with a Cessna 175 that has been re-engined with an
> O-360 and equipped with a STOL kit. It is an OK tug off a 5000' paved
> strip but not great. I've been towed by a 180 hp Pawnee (Jeff Cloud) and
> find that to be an excellent towplane.
Well, there's a relatively simple way to predict how the lower
horsepower plane will do under the same conditions. The tow speed is
pretty much set by the glider, so it won't change. The glider weight
won't change, and the weight of the tug will only decrease marginally
- say 30 lbs - so you can ignore that.
Climb rate is based on excess available power divided by weight. The
weight is probably around 2200 lbs for the glider-tug combo. Prop
efficiency is probably about 85%. Given that you will be running at a
density altitude of about 2000, and given a fixed pitch prop, either
engine is likely to be developing about 80% of rated power in the
climb.
OK, so the effective power difference will be
(.80)(180)-(.80)(150)=24hp.
With an 85% prop efficiency, that's (.85)(24)=20 hp.
One hp is 550 ft*lbs/sec, so the lost power is about 11,000
ft*lbs/sec.
Assuming a 2200 lb aircraft (glider and tug), that's 11,000/2200 = 5.1
ft/sec
So you will lose about 300 fpm in rate of climb, towing at the same
speed. Of course I have no idea what kind of climb rate you were
getting - my experience is that in the summer I can get about 400-500
fpm in a Pawnee 180 towing a two seater, but that's in Texas where 100
degrees with 95% humidity is the norm at the height of the season.
Takeoff roll will be correspondingly longer, but my guess is that with
5000 ft of pavement and no significant obstructions, you're going to
get off the ground OK. I'm not going to try and do those calculations
(they're way more complicated) but I will say that as a rule of thumb,
if you can't get 300 fpm steady state climb, then the takeoff roll and
initial climb over any obstacles is bound to get interesting.
My guess is that if you thought the Pawnee 180 was great (my
experience towing with one is off a 3000 ft rough obstructed strip,
where I considered it pretty marginal) then you'll be able to get by
with a Pawnee 150. If you were getting less than 600 fpm average with
the 180, you may want to rethink towing with the 150.
Michael
Udo Rumpf
> That engine works better in a Cessna 150 as a towplane or a C150 with
> 180 HP is a GREAT towplane. I've watched one beat a 235 Pawnee towing
> similar gliders and you have only 2/3 the fuel costs.
>
> Mike Borgelt
I concur with Mike, the Pawnee is one of the lousiest airframe to convert
horse power to altitude. What makes it attractive, it cheap to buy.
I like to add the Citabra , Piper Cup or even a stripped 172 with a 180HP
installed are much better tow planes all-round for club operations.
A 225HP or 250HP Pawnee is ok for a commercial outfits.
Still you are wasting money. On the rare occasion when fast turn around
is needed, well, that is the compromise one has to make.
See Paul Remde's site under tow planes.
Udo
Tim Mara
Callair......
Back a few years ago when this was all we had I didn't really know you were
supposed to go up faster :-)
The 150's are a "lot" weaker than the typical 235 Pawnees but they will do
the job probably as good as 150 Super Cubs (same wing, just dirtier on the
lift side (top with the struts), probably a tad better than a Citibria and
better than a Cessna 172.
I've towed the typical Schweitzer's, Blaniks, even Twin Grobs with the
150's, as long as you're not in a big hurry and the density altitude isn't
too high they are OK....great for teaching tows to students since they get
more time on tow and more slack rope than the bigger HP Pawnee's..
WE also have Pawnee's with the extended wing tip options.this helps the
235's too but I don't know if it's an option for the 150's.
Just don't try leaping over too many tall trees and you should be OK.
I know there were at least a couple 150's that had been converted to
180HP.......to me this seems like it would make a really good tow plane. The
150 Pawnee is quite a bit lighter airframe than the larger 235-260 Pawnee's
and the extra 30 HP would be all "climb HP"
go easy.....be safe
tim
Please visit the Wings & Wheels website at
www.wingsandwheels.com
"Wallace Berry" <ber...@acesag.auburn.edu> wrote in message
news:berrywd-8715AE...@fe01.atl2.webusenet.com...
Bruce Hoult
Wallace Berry <ber...@acesag.auburn.edu> wrote:
> Hi, Anyone out there every tow with a 150 hp Pawnee? How was it as a
> tug? We currently tow with a Cessna 175 that has been re-engined with an
> O-360 and equipped with a STOL kit. It is an OK tug off a 5000' paved
> strip but not great. I've been towed by a 180 hp Pawnee (Jeff Cloud) and
> find that to be an excellent towplane.
The Pawnees I've towed behind have mostly been 235+ HP and go well.
I once had a tow behind a 150 HP Pawnee (I think ... it was at Titoki,
near Whangarei NZ, in December '85). That was my first experience of
flying very low over the boundary fence, and I think my only experience
of flying low over the next fence as well. Certainly my only such
experience in something that wasn't a heavy glass two-seater (it was a
T53)
If you've got to use a 150, a Cub seems like a much better idea.
-- Bruce
Ian Johnston
<ber...@acesag.auburn.edu> wrote:
: Hi, Anyone out there every tow with a 150 hp Pawnee? How was it as a
: tug?
We had a 150hp Pawnee at Borders GC. It was perfectly adequate for
single seaters, but wasn't really up to the job for two-seaters,
especially in rough weather. It had a four-blade prop and a very
effective silencer, which made it astoundingly quiet but further
reduced its performance.
It now has a 160hp engine, a two-blade prop and no silencer, and its
performance isn't far off the other tug, a 180hp Super Cub. I believe
there is an STC for fitting a 180hp engine to the airframe in the US,
but if I recall correctly - the upgrade was done some years ago -
160hp was the maximum the CAA would permit without a new set of stress
calculations.
Ian
--
F.L. Whiteley
"Udo Rumpf" <uru...@reach.net> wrote in message
news:vc064r3...@corp.supernews.com...
owner and club member alike, launch rate when the sky pops!
Frank Whiteley;^)
Udo Rumpf
> owner and club member alike, launch rate when the sky pops!
>
> Frank Whiteley;^)
You are right, I did not think it through. Turn around time is totally
irrelevant.
The difference between a to 180 HP Citabria as an example and a
Pawnee 225HP is insignificant.
Let's see ~15 sec. turn around time at most between a 180 HP Citabria
and a 225HP pawnee to 2000 feet above ground starting at see level.
30 tows x 15sec = ~450 sec or ~7.5 minutes.
Total towing time over the 30 tows at 6 minutes per tow = 3 hours .
It would appear at that point you need two tow planes in any case.
Udo
F.L. Whiteley
tows with 8 minute turn around with K-13 and K-7 on 130hp with Rollson
Condor.
Frank
Hank Nixon
Reply:
I too have towed many times behind Jeff Cloud's 180 Pawnee. Was
sufficiently impressed to recomend this combination to our club.
Jeff's tow times are virtually the same as 235's when flying in the
same conditions.Lighter weight and 4 cylinders to maintain are also a
consideration.
That said, I think you will find that 150 Pawnee will be not quite as
good as 150 Cub. At 1/2 the cost, the price to performance is much
better.
With 5000 feet and lower altitude, safety should be fine provided
common sense is applied.
With availability of 235 and 260 Pawnees, many have become horsepower
snobs.
180 conversion is not STC'd. Several have been done and example 337's
are redily available. It is a field approval which is getting harder
to get in some places.
Can provide additional info directly if it would help.
UH
Wallace Berry
crwd...@hotmail.com (Michael) wrote:
> Well, there's a relatively simple way to predict how the lower
> horsepower plane will do under the same conditions. The tow speed is
> pretty much set by the glider, so it won't change. The glider weight
> won't change, and the weight of the tug will only decrease marginally
> - say 30 lbs - so you can ignore that.
>
According to the specifications, the 150 Pawnee is 476 lbs lighter than
the 235 hp Pawnees. Might that make a significant difference in the
towing performance?
Mark James Boyd
We have a PW-5, which is a very light glider, perhaps 400#
empty and 600# fully loaded. The Ace is 600# empty, 800#
with gas and pilot.
So how much climb can we get out of trying to lift 1400#
with 75hp? RPM is no problem, the Ace has a climb
prop. Speed may be a problem, since the Ace is Vy at
65mph. Maybe the 1-26 is a better option.
How about acceleration? A 3300 foot strip could be a real
problem. I wonder if a 5000 foot strip would work.
If the climb rate is 200-300 ft/min, downdrafts could
be interesting.
Since the 65hp cub/champ at 1232# (max gross) climbs
about 300fpm on a standard day, I'd bet with 75hp at
1400#, I'd get 200-300fpm.
Pretty marginal. Probably good to try it in the
winter on a cold day at a long runway :)
Mark
Bob
OK for a light single place plane but is dangerous with a 2 place. I was in
a Grob 103 with another passenger. The climb rates in dead air in the
evening were barely 100 ft/min. Any turbulence or vertical air movement
would make the tow impossible.
--
Bob & Lynne Greenblatt
Bob-...@comcast.net
Tjeerd Mulder
"Bob" <b...@spamtrap.com> schrieb im Newsbeitrag
news:BAE7A61F.2999E%b...@spamtrap.com...
> a Grob 103 with another passenger.
Uh ? 2 passengers in a Grob 103 :-)
dhofstee
>>a Grob 103 with another passenger.
> Uh ? 2 passengers in a Grob 103 :-)
I guess _they_ were in for a ride :-)
David
NL
Michael
> the 235 hp Pawnees. Might that make a significant difference in the
> towing performance?
I don't know where you got the 476 lbs. The PA-25-235 has a gross
weight of 2900 lbs; the PA-25 (this is the 150 hp version - it was
first and thus gets no dash number - because that's how Piper did it,
that's why) has a gross weight of 2300 lbs. Since the PA-25 has a max
cargo of 800 and a PA-25-235 has a max cargo of 1200, I'm pretty
confident there isn't a 476 lb difference in the empty weight.
However, the PA-25-235 is a different airframe, and likely heavier.
In any case, this isn't relevant. The 180 hp Pawnee (which you have
experience with) is simply a PA-25 with an engine change on a field
approval. There never was a PA-25-180. The 150 and 180 are identical
firewall-aft, and the only weight difference comes from the engine
installation - about 30 lbs.
Michael
Wallace Berry
crwd...@hotmail.com (Michael) wrote:
> Wallace Berry <ber...@acesag.auburn.edu> wrote
> > According to the specifications, the 150 Pawnee is 476 lbs lighter than
> > the 235 hp Pawnees. Might that make a significant difference in the
> > towing performance?
>
> I don't know where you got the 476 lbs. The PA-25-235 has a gross
> weight of 2900 lbs; the PA-25 (this is the 150 hp version - it was
> first and thus gets no dash number - because that's how Piper did it,
> that's why) has a gross weight of 2300 lbs. Since the PA-25 has a max
> cargo of 800 and a PA-25-235 has a max cargo of 1200, I'm pretty
> confident there isn't a 476 lb difference in the empty weight.
> However, the PA-25-235 is a different airframe, and likely heavier.
>
Well, I got the specs from www.risingup.com that list the empty weight
of the PA-25 as 1100 lbs and the PA-25-235 at 1576 lbs, thus the 476 lbs
figure. This difference seems suspiciously large to me and I wouldn't be
surprised if the numbers listed on the website are in error, but, that
is what they have. Your numbers appear to be directly from the type
certificate data sheet, which unfortunately, doesn't list the empty
weights. I have seen some other empty weight numbers which are off by
hundreds of pounds from both our numbers.
> In any case, this isn't relevant. The 180 hp Pawnee (which you have
> experience with) is simply a PA-25 with an engine change on a field
> approval. There never was a PA-25-180. The 150 and 180 are identical
> firewall-aft, and the only weight difference comes from the engine
> installation - about 30 lbs.
>
> Michael
Comparing the empty weight of the 150 to the 180 conversion, of course
would not be really relevant. However, I think you may have misread my
post. In my post that you quoted, I was responding to another poster who
was assuming that the PA-25-235 was only 30 lbs heavier than the
PA-25-150. Re-read my post and you will see that I was specifically
comparing the 150 to the 235 (and not to the 180).
Oh, and yes, I was aware that there was never a PA-25-180 and that the
conversion is on a field approval.
Tim Mara
say for certain that there is a LOT more difference in the weights than 30
pounds!
the 2 extra (larger) jugs alone would be far more than this and the Pawnees
150 airframe is smaller, and even the tubes in the fuselage are smaller.
I think the difference in basic weights is a lot closer to the 476 pounds
than the 30 pounds suggested......
tim
--
Please visit the Wings & Wheels website at
www.wingsandwheels.com
"Wallace Berry" <ber...@acesag.auburn.edu> wrote in message
news:berrywd-103ABF...@fe01.atl2.webusenet.com...
Michael
> would not be really relevant.
Why not? You glider weight won't change, your pilot weight won't
change, and your fuel weight may change a little - and then again it
may not. Where I used to tow, we put the same amount of fuel in the
180 and the 235.
The basis of the post was this - aerodynamics remain the same, speeds
remain the same, you lose a little bit of weight (but probably not
enough to matter), and you lose some power which directly translates
into climb rate. Thus, given your experience with the 180, the
performance of the 150 under the same conditions is predictable.
> However, I think you may have misread my
> post. In my post that you quoted, I was responding to another poster who
> was assuming that the PA-25-235 was only 30 lbs heavier than the
> PA-25-150.
OK, mea culpa. I use a threaded newsreader, and your post showed up
as being a reply to mine.
Michael
Aspley Nursery
I have towed behind both and I will have a 235 any day especially with a big
heavy sailplane on a hot day in northern Australia (home).
The other point worth noting is weight and HP aren't the only consideration.
The 235 gets going on tow on our relatively rough grass strips much faster,
whereas the smaller engine planes just can't get the glider rolling for a
while.
We have a Super Diomana sailplane / tug and it is similar. No problems most
of the time, andcertanly not when the glider gets airborne.
Also towed recently behind a Cessna 150 wit an auto engine (Chevy) and it
was great. Just like a Pawnee 235. Manny of our site also have fun with
noise and multi bladed props certainly help.
A club in New South Wales is trying towing with a Bergfalke motor glider,
but I believe again this is off bitumen. Great stable and cheap tows though
although probably not for the gassed up Nimbus.
Hope my thoughts help.
Robert Percy
If you want to look, I fly out of Queensland Australia. It is as good a flat
land site as you get I believe although I'm biased.
"Michael" <crwd...@hotmail.com> wrote in message
news:449a3d6e.0305...@posting.google.com...
Wallace Berry
"Aspley Nursery" <aspl...@caboolture.net.au> wrote:
> The practical test is doing it.
>
> I have towed behind both and I will have a 235 any day especially with a big
> heavy sailplane on a hot day in northern Australia (home).
>
Thanks to everyone who responded to my request for info on towing with a
150 hp Pawnee. Unfortunately, the deal on the 150 Pawnee didn't go
through. Our intent was to re-engine it to 180, but we would have used
it for awhile at 150. Obviously, more power is better in this case, but
it seems that the consensus of those who had actually towed with a 150
Pawnee is that it would have been acceptable under our conditions.
We subsequently found a 260 Pawnee at a reasonable price but someone
made an offer on it before we did.
If any one knows of a 180 Pawnee for sale, I would very much appreciate
hearing about it.
Good soaring to you all,
Wally
goneill
email/letter
to every owner within suitable distance and see how many respond ,if you add
a request to that enquiry to reply to you if they know of any other owner
selling ,should give you a good selection.
Our Towmaster recently did that type of exercise and was surprised at the
response.news:berrywd-6FF1A4...@fe01.atl2.webusenet.com...
youngbl...@gmail.com
> Hi, Anyone out there every tow with a 150 hp Pawnee? How was it as a
> tug? We currently tow with a Cessna 175 that has been re-engined with an
> O-360 and equipped with a STOL kit. It is an OK tug off a 5000' paved
> strip but not great. I've been towed by a 180 hp Pawnee (Jeff Cloud) and
> find that to be an excellent towplane.
>
> We are buying a low time Pawnee currently equipped with a low time 150
> hp engine. We hope it will tow at least as well as the C-175. If so, we
> will keep it and eventually re-engine it to 180 hp.
>
> Thanks,
>
> Wally
I own a Pawnee 150 that is a pretty good tow plane, she is not going to compete with the 235 by no means, but she will get you going at about 500 fpm on most any given day. Yes, we are at near sea level, but the days can get hot and humid. My strip is about 2000 feet and ole Dusty gets me up and out whenever I desire. The aircraft is over 500 pounds lighter that the 235, and is much lighter on the controls.
One of these days I will repower Dusty and get a 180 hp hung on the nose, but until then she keeps me in the air.
