Max towing weigth for PA-18 150 hp and 180 hp?

Originally Posted by Bill D

On Apr 23, 3:20*pm, Ventus_a
wrote:
Bill D;813718 Wrote:

snip

Can't agree that most recent European 2 seaters specify 600kg weaklinks
for aerotow. *The Duo Discus for example is 50% or so higher and the DG
1000 is higher again at 1100 DaN

Having said all that here in New Zealand there are some operations that
use PA-18 180s and they variously tow Duos and ASH 25s so they are well
capable of handling the bigger ships subject to density altitude
considerations

Colin

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Ventus_a

From the DG-1000 manual page 2.10: "6000 N + 600 N (1323 lbs. + 132
lbs.) for tow
behind slow tow planes" Which I think would include a PA-18.

The Duo allows a 700 daN weak link but that's not 50% higher.

Don't tell half the story Bill.

The cockpit placard for towing in the Duo specifies 910 daN as the maximum with out referencing the minimun allowed (700 daN) as stated in the flight manual. My mistake for not quoting the allowable range in my original post. I should also have said 'up to 50% or so higher" :-)

The DG manual says regarding 'slow' tow planes, "for tow behind slow towplanes eg. Ultralight planes or touring motorgliders". Last time I looked a PA-18 150 or PA-18 180 was neither an ultralight or a touring motorglider

Colin

Guys

This is not a question about weak links or the capability in practice. We have been towing gliders 600 kg with Super Cub 150/180 for more than 30 years. The problem is that someone recently found a supplement to the Flight Manual stating that the Super Cub is limited to tow gliders 600 kg and now wants us to put a 600 kg limit on all Cubs. (Yes I know..........)

It seems that Piper never delivered a Cub with a tow hook so all installations are done on a National level with National approvals. Do you know of any such approval that you can direct me to? Especially in Europe.

Thanks
Robert

Checked FAA Advisory Circular 43-13.2, Chapter 8. May or may not help Euro ops, but...
Early on it explains how the structural limits of various tow aircraft are determined. There is a simple formula given for that determination. Tow limits for US aircraft are based on structural limits for the aircraft, not performance limits. Generally, the FAA uses the breaking strength of the tow rope to determine the max weight of the towed glider. Also that weight is usually placarded around 1200 lbs. maximum towline strength to comply with the structural limitations, depending on the aircraft.

In conjunction with that, the FAA also states operationally that the tow line strength for the glider must be no less the 80% of the glider weight or no more than 200% of that weight. So, at least in the US, a tug with a 1200 lb, tow line limit can legally and theoretically to up to a 1500 lb glider (Cub and 2-32?), and still be with in the limits of the towing aircraft. The aircraft performance capabilities are another story and are the responsibility of the operator.

Don't know if this could help or not.

Linwood

Yet another corollary on Murphies Law:

The authorities will stuff it up in imaginative and contrary ways that
belie rational belief...

The others a
Things will go wrong in the worst possible way
Murphy was an optimist, and
There is always one more idiot than you would have thought possible...

Bruce
On 2012/04/24 8:41 PM, Robert Danewid wrote:
Guys

This is not a question about weak links or the capability in practice. We have been towing gliders600 kg with Super Cub 150/180 for more than 30 years. The problem is that someone recently found a supplement to the Flight Manual stating that the Super Cub is limited to tow gliders600 kg and now wants us to put a 600 kg limit on all Cubs. (Yes I know..........)

It seems that Piper never delivered a Cub with a tow hook so all installations are done on a National level with National approvals. Do you know of any such approval that you can direct me to? Especially in Europe.

Thanks
Robert

--
Bruce Greeff
T59D #1771

Our club operates a PA 180 HP with a four blade prop. Max mass of the
towed glider per flight manual is 620 kg (decreasing with density
altitude). Max mass of the PA during towing operations is 690kg.
I did look it up a couple of weeks ago to know whether it could tow an
ASH25 with two pilots - which it can't.

On Apr 25, 2:39*pm, Bert TW wrote:
Our club operates a PA 180 HP with a four blade prop. Max mass of the
towed glider per flight manual is 620 kg (decreasing with density
altitude). Max mass of the PA during towing operations is 690kg.
I did look it up a couple of weeks ago to know whether it could tow an
ASH25 with two pilots - which it can't.

Oups, forgot - we're in Switzerland.

On Apr 24, 2:58*pm, Steve wrote:
Checked FAA Advisory Circular 43-13.2, Chapter 8. *May or may not help Euro ops, but...
Early on it explains how the structural limits of various tow aircraft are determined. *There is a simple formula given for that determination. *Tow limits for US aircraft are based on structural limits for the aircraft, not performance limits. *Generally, the FAA uses the breaking strength of the tow rope to determine the max weight of the towed glider. *Also that weight is usually placarded around 1200 lbs. maximum towline strength to comply with the structural limitations, depending on the aircraft.

In conjunction with that, the FAA also states operationally that the tow line strength for the glider must be no less the 80% of the glider weight or no more than 200% of that weight. *So, at least in the US, a tug with a 1200 lb, tow line limit can legally and theoretically to up to a 1500 lb glider (Cub and 2-32?), and still be with in the limits of the towing aircraft. The aircraft performance capabilities are another story and are the responsibility of the operator.

Don't know if this could help or not.

Linwood

It appears AC 43-13.2 Ch. 8 needs updating.

91.9 requires gliders be operated in strict compliance with their
flight manuals.
These manuals are calling out aero tow weak links much stronger than
1200 Lb-F.
91.309 requires either the rope or a weak link at the tug to be
stronger than the glider link.
The result is the tug hook needs to be much stronger than 1200 Lb-F.

We need to be using Tost tug hooks and that installation should be
stronger than the 2570 Lb-F Tost load limit.

At 12:40 25 April 2012, Bert TW wrote:
On Apr 25, 2:39=A0pm, Bert TW wrote:
Our club operates a PA 180 HP with a four blade prop. Max mass of the
towed glider per flight manual is 620 kg (decreasing with density
altitude). Max mass of the PA during towing operations is 690kg.
I did look it up a couple of weeks ago to know whether it could tow an
ASH25 with two pilots - which it can't.

Oups, forgot - we're in Switzerland.

In the UK the PA18-150 is cleared to tow up to 2 gliders max combined
weight 1900lb (862kg), and the PA18-180 cleared to tow up to two gliders
max combined weight 2400lb (1088kg). The weak link in the tow rope has to
be maximum 1000lb (454kg) if towing 1 glider, and a maximum of 1300lb
(590kg) if towing two gliders.
This is all on the CAA change sheet No.1, (dated 25 April 1980) to FAA
approved flight manual report 1054, which is the PA18 Super Cub UK manual.

Hope that helps

Dave Bullock