Towplane performance

Looking for 300ft in the air at departure end, in a Janus (assume two
seats
loaded) at max GW take off from a 2200ft long runway is very optimistic.

Our 260 HP Pawnees normally get around 600 fpm at 65 knots with a Janus
(or Grob Twin for that matter) with two people. That's a climb angle of
about 1:11. OK, so you can get a better angle with a slower speeed, but
not *that* much better.

Great explanations..
Our 235HP Pawnee will average about 400-500fpm with a two up 2-33 or Grob
103.
And we break ground with about 1500ft runway remaining... so.. about 200ft
at departure end.
We are lifting off at about 55KIAS and towing at 60 for a 1-26 and 65 for
the Grob.

BT

Roy wrote:
Our operation has started the hunt for a new towplane.
The main criteria is that from our 2200ft strip at sea level we need
to have a two seater (janus) "over the fence" at 300ft in still air.

What would you recommend?
Dont dwell on purchase cost but rather performance/running costs

We would consider
a) Used
b) New
c) Experimental/anything else.

Thanks for your thorts.

If performance is your only criteria, the following should be
considered. A 450 Steerman, a 650 Steerman or a 400 or turbine Piper
Brave. These are all crop dusters so you have to be careful what you
buy. The wings time out on the Brave and require major repair at that
time. The performance is directly proportional to the cost of operation
in just about the following order turbine Brave, 650, 450 and 400
Brave. The 650 Steerman with full power at sea level will make you
think you are on a winch. There are a lot of Braves available at
reasonable cost but see previous.

I agree that for really good performance and ok cost,
a nice big turbine is a neat deal. A lot of cropdusters
have gone from the radials to the turbines for performance/cost
reasons.

At 15:31 04 April 2005, 1jh wrote:
Roy wrote:
Our operation has started the hunt for a new towplane.
The main criteria is that from our 2200ft strip at
sea level we need
to have a two seater (janus) 'over the fence' at 300ft
in still air.

What would you recommend?
Dont dwell on purchase cost but rather performance/running
costs

We would consider
a) Used
b) New
c) Experimental/anything else.

Thanks for your thorts.

If performance is your only criteria, the following
should be
considered. A 450 Steerman, a 650 Steerman or a 400
or turbine Piper
Brave. These are all crop dusters so you have to be
careful what you
buy. The wings time out on the Brave and require major
repair at that
time. The performance is directly proportional to the
cost of operation
in just about the following order turbine Brave, 650,
450 and 400
Brave. The 650 Steerman with full power at sea level
will make you
think you are on a winch. There are a lot of Braves
available at
reasonable cost but see previous.


Mark J. Boyd

"Roy" wrote in message
om...
Many thanks for all the advice and suggestions so far.

Non of the suggestions were for other than standard (old) aircraft
products.

It has been suggested that an RV9 with a big motor (160-200hp) would
be great to do the job.

Anyone else considered this approach?
We are not a commercial operation and dont have to pay our pilots.
There is no insurance problem so this solution has some appeal. ie
new airframe, easy repair & maintenance.

"Experimental - Amateur Built" aircraft will always have a "No glider
towing" paragraph in their operation limitations letter. However, Sport
Light Aircraft under the new regs seem to have a loophole that allows glider
towing for profit.

Actually the key design parameter isn't the engine it's the propeller and
after that, the wing. If you start with a prop optimized for max thrust at
towing speed and then a wing optimized for that speed, the HP requirements
go way down. This assumes that the prop RPM can be reduced by belts or
gearing.

Maybe somebody should cook up an SLA design optimized for towing. This
would be a very efficient and very quiet airplane.

Bill Daniels

Many thanks for all the advice and suggestions so far.

Non of the suggestions were for other than standard (old) aircraft
products.

It has been suggested that an RV9 with a big motor (160-200hp) would
be great to do the job.

Anyone else considered this approach?
We are not a commercial operation and dont have to pay our pilots.
There is no insurance problem so this solution has some appeal. ie
new airframe, easy repair & maintenance.

Roy wrote:
It has been suggested that an RV9 with a big motor (160-200hp) would
be great to do the job.

Anyone else considered this approach?
We are not a commercial operation and dont have to pay our pilots.
There is no insurance problem so this solution has some appeal. ie
new airframe, easy repair & maintenance.

If you are in the US, towing gliders with experimental aircraft is
prohibited by the FAA. I can't remember the exact place where it is
spelled out (it's probably in an AC), I'm sure someone else will know...

"Roy" wrote in message
om...
Many thanks for all the advice and suggestions so far.

Non of the suggestions were for other than standard (old) aircraft
products.

It has been suggested that an RV9 with a big motor (160-200hp) would
be great to do the job.

Anyone else considered this approach?
We are not a commercial operation and dont have to pay our pilots.
There is no insurance problem so this solution has some appeal. ie
new airframe, easy repair & maintenance.

Have a look at this site.
http://www.soarmn.com/soaring_files/...ison_table.jpg
This Towplane table was done in 1994. The calculation are all referenced to
see level and standard temperature. The performances appear high,
but are not, because most of the comments on this group referred to High
temperature and high altitude. All Climb performances are with a fully
loaded
twin Grob. Acceleration on the Ground was not taken into account.
For example if the temperature is 80F and a 1000ft the factor becomes .77
Please note how well the Zenith 300 with a 180 HP does.

I could well imagine Dick VanGrunsven RV 9 with a 180HP would do very well
but
the RV 10 would be a better choice, as the airframe is stronger and designed
to take a bigger engine, the airframe would still be well under 1500lb if it
is a
very basic tow plane. For example the RV 9 with a pilot and fuel and a max
160HP
( allowed only) has a power loading of 10.

The RV10 with the same pilot and fuel would, but 180 HP, would have the
same
power loading as the RV9. The RV 10 has a larger wing area, it would climb
better
at the speeds we tow at. Also the Airframe is designed for up to 260HP.

For a club with a small membership and limited options I would favour a
stripped down
C-170 or 172 with 180HP if Summer temperature and see elevation allow.
Parts and services are readily available and the performance is not bad at
all for 180HP.
Regards
Udo

Uh, but I think you might be missing an important point. Experimental
aircraft such as the RV series can't be used for hire. If the plane and
pilot are provided free, and not compensated in any way, then it might
be doable. I guess you'd have to find a pilot that is only interested
in building time and not wanting to make money...I'm out


Scott


Udo Rumpf wrote:

"Roy" wrote in message
om...

Many thanks for all the advice and suggestions so far.

Non of the suggestions were for other than standard (old) aircraft
products.

It has been suggested that an RV9 with a big motor (160-200hp) would
be great to do the job.

Anyone else considered this approach?
We are not a commercial operation and dont have to pay our pilots.
There is no insurance problem so this solution has some appeal. ie
new airframe, easy repair & maintenance.


Have a look at this site.
http://www.soarmn.com/soaring_files/...ison_table.jpg
This Towplane table was done in 1994. The calculation are all referenced to
see level and standard temperature. The performances appear high,
but are not, because most of the comments on this group referred to High
temperature and high altitude. All Climb performances are with a fully
loaded
twin Grob. Acceleration on the Ground was not taken into account.
For example if the temperature is 80F and a 1000ft the factor becomes .77
Please note how well the Zenith 300 with a 180 HP does.

I could well imagine Dick VanGrunsven RV 9 with a 180HP would do very
well but
the RV 10 would be a better choice, as the airframe is stronger and
designed
to take a bigger engine, the airframe would still be well under 1500lb
if it is a
very basic tow plane. For example the RV 9 with a pilot and fuel and a
max 160HP
( allowed only) has a power loading of 10.

The RV10 with the same pilot and fuel would, but 180 HP, would have
the same
power loading as the RV9. The RV 10 has a larger wing area, it would
climb better
at the speeds we tow at. Also the Airframe is designed for up to 260HP.

For a club with a small membership and limited options I would favour a
stripped down
C-170 or 172 with 180HP if Summer temperature and see elevation allow.
Parts and services are readily available and the performance is not bad
at all for 180HP.
Regards
Udo

"Scott" wrote in message
...
Uh, but I think you might be missing an important point. Experimental
aircraft such as the RV series can't be used for hire. If the plane and
pilot are provided free, and not compensated in any way, then it might be
doable. I guess you'd have to find a pilot that is only interested in
building time and not wanting to make money...I'm out


Scott
I did not make a point about the viability as it relates to
the regulation, but rather performance.
Udo




Udo Rumpf wrote:

"Roy" wrote in message
om...

Many thanks for all the advice and suggestions so far.

Non of the suggestions were for other than standard (old) aircraft
products.

It has been suggested that an RV9 with a big motor (160-200hp) would
be great to do the job.

Anyone else considered this approach?
We are not a commercial operation and dont have to pay our pilots.
There is no insurance problem so this solution has some appeal. ie
new airframe, easy repair & maintenance.


Have a look at this site.
http://www.soarmn.com/soaring_files/...ison_table.jpg
This Towplane table was done in 1994. The calculation are all referenced
to
see level and standard temperature. The performances appear high,
but are not, because most of the comments on this group referred to High
temperature and high altitude. All Climb performances are with a fully
loaded
twin Grob. Acceleration on the Ground was not taken into account.
For example if the temperature is 80F and a 1000ft the factor becomes
.77
Please note how well the Zenith 300 with a 180 HP does.

I could well imagine Dick VanGrunsven RV 9 with a 180HP would do very
well but
the RV 10 would be a better choice, as the airframe is stronger and
designed
to take a bigger engine, the airframe would still be well under 1500lb if
it is a
very basic tow plane. For example the RV 9 with a pilot and fuel and a
max 160HP
( allowed only) has a power loading of 10.

The RV10 with the same pilot and fuel would, but 180 HP, would have the
same
power loading as the RV9. The RV 10 has a larger wing area, it would
climb better
at the speeds we tow at. Also the Airframe is designed for up to 260HP.

For a club with a small membership and limited options I would favour a
stripped down
C-170 or 172 with 180HP if Summer temperature and see elevation allow.
Parts and services are readily available and the performance is not bad
at all for 180HP.
Regards
Udo

In article ,
Marc Ramsey wrote:

If you are in the US, towing gliders with experimental aircraft is
prohibited by the FAA.

That seems silly.

Sure, taking some random aircraft and using it to tow a glider would be
a silly idea, but surely it's ok to design and build your own
experimental aircraft for the specific purpose of towing gliders!

I seem to recall an experimental aircraft called "White Knight"
air-dropping a glider called "SpaceShipOne", with the FAA administrator
present.

--
Bruce | 41.1670S | \ spoken | -+-
Hoult | 174.8263E | /\ here. | ----------O----------