Tow plane types/mods for high density altitude glider towing

[son_of_flubber]

What are your favorite aircraft types (and modifications) for glider towing in high density altitude and/or short runways?

[sgs...@gmail.com]

Ag-Cat with Wasp Jr.!

[JS]

On Monday, August 12, 2019 at 6:57:00 PM UTC-7, sgs...@gmail.com wrote:
> Ag-Cat with Wasp Jr.!

Jerry Marshall's 400HP Brave!
He never did get the turbine Brave ready for towing.
Jim

[AS]

On Monday, August 12, 2019 at 9:38:43 PM UTC-4, son_of_flubber wrote:
> What are your favorite aircraft types (and modifications) for glider towing in high density altitude and/or short runways?

I fly a heavy two-seater and have been towed in hot/high locations (DA around 10k') behind a Pawnee 235, CallAir A9, C188 AgWagon and a C185 SkyWagon. All four did a reasonable job with the C188 being the best. I think the Pawnee and definitely the two Cessnas had a constant speed prop and did actually better than the CallAir, which I was told had the most HP. I have no idea if any one of them had turbo-charged engines. A low wing, constant speed prop and lots of uumph seems to be the winning combination.

Uli
'AS'

[Papa3]

On Monday, August 12, 2019 at 9:38:43 PM UTC-4, son_of_flubber wrote:

> What are your favorite aircraft types (and modifications) for glider towing in high density altitude and/or short runways?

They used to have 450hp Stearman at Stroudsburg. It wasn't a tow so much as being dragged vertically into the air.


P3

[son_of_flubber]

On Monday, August 12, 2019 at 11:04:05 PM UTC-4, Papa3 wrote:

> They used to have 450hp Stearman at Stroudsburg. It wasn't a tow so much as being dragged vertically into the air.
>
>
> P3

I once saw Jim Parker take off and tow a glider behind a Pitts Special... at 100 knots. They towed XC to an air show.

[mark...@aol.com]

Dennis Tito tows with a turbine Cessna 206 or 207. Perlan is using a turbine Grob. I have towed behind a turbine Ag Cat. Agree on the “being dragged skyward” comment. Was at 2K agl at the end of the runway.

I Have towed a loaded SGS 2-32 and loaded Janus out of Aspen, CO dozens of times with a 180 Cub. Not recommended.....

The 260 and 235 Pawnee, C-188, or big engine 182, 180, 185 have all worked well at Ely and Parowan and other high desert sites for decades.

[Peter F]

I've seen a tow behind a Pilatus Turboporter at Gap Tallard

At 04:14 13 August 2019, mark...@aol.com wrote:
>Dennis Tito tows with a turbine Cessna 206 or 207. Perlan is using a

>turbi=

>ne Grob. I have towed behind a turbine Ag Cat. Agree on the

>=E2=80=9Cbein=
>g dragged skyward=E2=80=9D comment. Was at 2K agl at the end of the
>runway=
>..

>
>I Have towed a loaded SGS 2-32 and loaded Janus out of Aspen, CO dozens
of

>=

>times with a 180 Cub. Not recommended.....
>
>The 260 and 235 Pawnee, C-188, or big engine 182, 180, 185 have all
worked

>=

[James Metcalfe]

At 08:07 13 August 2019, Peter F wrote:
>I've seen a tow behind a Pilatus Turboporter at Gap Tallard

I've *had* a tow behind a Pilatus at Gap-Tallard. My pupil had no trouble
flying the 2-seat glider ... but the Pilatus pilot (disappointingly?) used

significantly reduced power!

[Dan Marotta]

A 300-hp Ag Wagon works just fine at 9,500' density altitude.  Quite
comfortable for the tow pilot, too!

--
Dan, 5J

[Dan Marotta]

Uli,

It sounds like you're talking about Moriarty.  The Pawnee has 260 hp and
a CS prop, the Call Air has 290 hp and a fixed pitch prop, and the Ag
Wagon has 300 hp and a constant speed prop.

The Call Air, with its 94" prop is the noisiest of the bunch with its
supersonic tip speed, but most of the tow pilots don't reduce RPM on the
other two after getting safely airborne, resulting in about as much
noise.  I hate to think of all those 10-15 minute tows at full RPM.  I
wonder if the 5-minute limit is for RPM or for max power (which isn't
available at our altitudes).  When I was towing, I always reduced RPM
after we were both established in climb and I never got any complaints
from glider pilots.

--
Dan, 5J

[AS]

Yep - and Montrose, CO behind a beautiful C185. :-)

Uli
'AS'

[mgr...@muroc.k12.ca.us]

And the best towplane "modification" is a highly competent pilot in the tug.

[Bob Youngblood]

Our situation here in Florida is quiet different because of our MSL. I have a Pawnee with 180 hp. It does very well for the most part. I also have a 235 Pawnee that is certainly more powerful, but After all is said I would rather have the 180 Pawnee for my personal use. We call it the Yellow Gorilla, and it has done a great job for our club.

[Frank Whiteley]

On Monday, August 12, 2019 at 7:38:43 PM UTC-6, son_of_flubber wrote:
> What are your favorite aircraft types (and modifications) for glider towing in high density altitude and/or short runways?

Mark Keene once told me about towing with one of these at Uvalde making a 2000ft tow and return in under three minutes. https://en.wikipedia.org/wiki/SIAI-Marchetti_SM.1019

28 variants on the US registry.

Frank Whiteley

[uncl...@ix.netcom.com]

I towed behind Mark in my '28. We had 2000 feet in 1:40. He told me he was using 40% power.
UH

[JS]

Regarding mods, the eTug deserves mention.
A Pawnee with a 350 cubic inch Chevy LS1 running on Mogas. Early experiments provided too steep a climb angle, so the original 4-blade prop was adjusted to decrease the climb rate. Now it has a different prop.
I've hooked many gliders up to eTug, yet to tow behind it.

https://www.glidingclub.org.au/members-only/aircraft/etug/

These days a crate LS3 engine can be purchased for about $8000 and produces 430HP on Mogas. Car engines require a PSRU (speed reduction).

https://www.gmperformancemotor.com/parts/19370416.html?gclid=Cj0KCQjwv8nqBRDGARIsAHfR9wC30A7wF3SFSrhYOBoLdkinr_7MGZMpHxignUEhA1qfW5iBSSEbHwAaAhPlEALw_wcB

Not much concern about shock cooling or leaded Avgas going away.
Jim

[Nigel Pocock]

A Zlin Z-137t would seam to do the job. This is turbine powered and
there is a video on U tube of one towing 9 x L13 Blanics in one tow.

[Frank Whiteley]

Now that I think about it, I believe Mark said his tow cycle time was 2.5 minutes. Must have been an interesting view from the glider;^)

Frank

[Dan Marotta]

Leave it to the Italians.  A Bird Dog with panache!

--
Dan, 5J

[Dan Marotta]

That is super!

Was there any difficulty with your CAA or was the GFA authorized to make
those mods?

--
Dan, 5J

[Craig Funston]

Akaflieg Stuttgart just flew their concept of an optimized towplane. Congratulations to all the students and their mentors.

https://akaflieg.hg.stuvus.uni-stuttgart.de/2019/08/14/erstflug-fs35-harpyie/?fbclid=IwAR1rgq8zp1xdRFvQTqvAQGbklVeiF76CE0bKvKbdxjlFvEvgsGCyBGeZLCI

Craig

[John Foster]

That looks promising. Now to make them "affordable".

[Martin Gregorie]

I remember a couple of specialist tow planes appearing a few years ago,
apparently to disappear without trace a bit later. One came from an
Akaflieg and was dual purpose: two seat aerobatic aircraft and tow-plane.
The other was from the Finnish Akaflieg equivalent - the PIK-27.

Are either in use as tow-planes now?

Has more than the prototype of either type been built?


--
Martin | martin at
Gregorie | gregorie dot org

[christoph...@googlemail.com]

The Mü30 Schlacro from Akaflieg Munich is in use and serves as an excellent towplane. Schlacro comes from "Schlepp" (Tow) and "Acro". It will probably be around at WGC 2020 at Stendal. Currently it is working there during Idaflieg summer camp. Since it was built by the students, it unfortunately is a unique aircraft.

The fs35 is a very interesting concept indeed, combining a motorglider similar to a HK36 Super Dimona with a 155hp turbocharged aircraft diesel engine.

[AS]

On Wednesday, August 14, 2019 at 2:21:54 PM UTC-4, christop...@googlemail.com wrote:
> The Mü30 Schlacro from Akaflieg Munich is in use and serves as an excellent towplane. Schlacro comes from "Schlepp" (Tow) and "Acro". It will probably be around at WGC 2020 at Stendal. Currently it is working there during Idaflieg summer camp. Since it was built by the students, it unfortunately is a unique aircraft.
>
> The fs35 is a very interesting concept indeed, combining a motorglider similar to a HK36 Super Dimona with a 155hp turbocharged aircraft diesel engine.

A great concept, indeed! The turbo-charged Diesel engine should make the Hot/High condition secondary. Here is the link to the engine manufacturer's site:
http://www.continentaldiesel.com/typo3/index.php?id=84&L=1

Uli
'AS'

[JS]

On Wednesday, August 14, 2019 at 7:33:57 AM UTC-7, Dan Marotta wrote:

> That is super!
>
> Was there any difficulty with your CAA or was the GFA authorized to make
> those mods?

> --
> Dan, 5J

The original LS1-mod Pawnee, VH-CUR is EXP. Don't think they've certified one yet.
Jim

[Bob Youngblood]

On Monday, August 12, 2019 at 9:38:43 PM UTC-4, son_of_flubber wrote:
> What are your favorite aircraft types (and modifications) for glider towing in high density altitude and/or short runways?

The C-188 300 constant speed prop is a great towplane. I am already planning to make one my next project.

[uncl...@ix.netcom.com]

Don't do it if you have neighbors. Second loudest tug I've seen, behind only a 650 Agcat.
UH

[Charlie M. (UH & 002 owner/pilot)]

Hmmmm.....not sure if our field.....remember a short time tug that was great, but maybe 75% throttle lit up the local PoPo....
Yeah.....not many tows, but they were fun......
;-)
;-)

[michael...@gmail.com]

On Tuesday, August 13, 2019 at 11:38:43 AM UTC+10, son_of_flubber wrote:
> What are your favorite aircraft types (and modifications) for glider towing in high density altitude and/or short runways?

eTugs are now certified in Australia and are in production. Tow costs are half avgas powered PA25 - 235 tugs.
Michael

[Craig Funston]

Michael, are they producing a two seat version of the eTug?

Cheers,
Craig

[michael...@gmail.com]

On Tuesday, August 13, 2019 at 11:38:43 AM UTC+10, son_of_flubber wrote:
> What are your favorite aircraft types (and modifications) for glider towing in high density altitude and/or short runways?

Yes, there is a one and one half seater (single controls) has been converted, but remember the conversions are only of the existing aircraft. Aircraft are not being made from scratch.
Michael

[Per Carlin]

If you cant tow your glider behind a Turbo Čmelák, then shoud it not been towed at all :)

http://www.flugzeuginfo.net/acdata_php/acdata_z37t_en.php

[George Underhill]

I saw a friend towed (pulled) aloft in a IS28b2 Lark by Steve Wolf in his 450hp Samson biplane at an airshow in Spokane, WA. It was an impressive climb angle, to say the least.

[2G]

On Friday, August 16, 2019 at 1:30:50 PM UTC-7, George Underhill wrote:
> I saw a friend towed (pulled) aloft in a IS28b2 Lark by Steve Wolf in his 450hp Samson biplane at an airshow in Spokane, WA. It was an impressive climb angle, to say the least.

I only consume 1/2 gallon to launch my ASH31Mi motorglider to 3kft (the same was true for the 26e and DG400, and most every other self-launcher that I can think of, well maybe not the Space Shuttle). So, for a 4 hour flight my "burn rate" is 1 pint per hour.

Tom

[son_of_flubber]

On Thursday, August 22, 2019 at 11:50:40 AM UTC-4, 2G wrote:

> I only consume 1/2 gallon to launch my ASH31Mi motorglider to 3kft (the same was true for the 26e and DG400, and most every other self-launcher that I can think of, well maybe not the Space Shuttle). So, for a 4 hour flight my "burn rate" is 1 pint per hour.

Self-launch gliders are obviously appealing, but I'm curious about their limitations wrt density altitude and turbulence.

What is your climb rate in your typical density altitude?

Do you ever launch in turbulent conditions with lots of sink?

What density altitude leads you to cancel your flight?

What is the highest density altitude that you have launched in?

[Dan Marotta]

It's not the same with other self-launchers, of course, but my S10-VT
has a turbocharged, 4-cylinder engine rated at 115 (nominal)
horsepower.  With the turbo, it achieves its rated power to a very high
altitude, which I haven't seen stated, but it has a published service
ceiling of 33,000' MSL.  Density altitude has no effect on it other than
some reduction in propeller efficiency and engine temperature limits.  I
imagine the higher true airspeed for a given IAS at takeoff at high
altitude airports makes up for reductions in wing lift.  At maximum
power it burns around 5 gallons/hour (about 3.2 gph in cruise at 18,000'
MSL for repositioning flights), so I'd guess I burn less than a half
gallon of gas per normal soaring flight, including taxi and takeoff.

Engine overhaul will cost a few pennies more than with the smaller ships...

--
Dan, 5J

[son_of_flubber]

Also...

How long is your runway? Is it level? Is it paved?

[2G]

On Friday, August 23, 2019 at 9:30:29 AM UTC-7, son_of_flubber wrote:
> On Thursday, August 22, 2019 at 11:50:40 AM UTC-4, 2G wrote:
>
> > I only consume 1/2 gallon to launch my ASH31Mi motorglider to 3kft (the same was true for the 26e and DG400, and most every other self-launcher that I can think of, well maybe not the Space Shuttle). So, for a 4 hour flight my "burn rate" is 1 pint per hour.
>
> Self-launch gliders are obviously appealing, but I'm curious about their limitations wrt density altitude and turbulence.
>
> What is your climb rate in your typical density altitude?

At 2000 ft DA it is 500 ft/min; at 9000+ DA it is 300 ft/min. Always seeking lift, so this is mixed.

>
> Do you ever launch in turbulent conditions with lots of sink?

Not with lots of sink - try to launch when there is lift.

>
> What density altitude leads you to cancel your flight?

None.

>
> What is the highest density altitude that you have launched in?

9600 ft.

[jfitch]

On Friday, August 23, 2019 at 9:30:29 AM UTC-7, son_of_flubber wrote:

My ASH26Mi climbs at about 450 ft/m at 9000 ft density altitude. A little better than a Pawnee towing me. At sea level it is close to 900 ft/min. I routinely launch at 9000 density (typical for a noon launch at Truckee) and have done as high as 9999 (that's the limit of the electronic sign at the end of Runway 20).

[Darryl Ramm]

ASH26Mi. “But there is no such thing” :-)

[JS]

On Monday, August 26, 2019 at 12:36:49 PM UTC-7, Darryl Ramm wrote:
> ASH26Mi. “But there is no such thing” :-)

There is ONE such thing. Would have been two if I hadn't run out of money.
Jim

[Darryl Ramm]

John’s ASH26Mi is a thing of beauty. Having asked Schleicher about a 26E to Mi conversion a long time ago I was blown away by the amount of work this took.

[Ross]

Best tow plane ( well helicopter) was a Hughes 500 D at the Warbirds airshow in NZ and the opening of the world gliding champs.
Take-off roll was about 60m and it went up at 1600ft per min.
The trick at the top was slowing the helicopter down till the glider stalled and hung on the belly hook.
Need to get the videos of this uploaded sometime. Make for great viewing

[Darryl Ramm]

Ah but can you hand hold a tow rope behind a 500D? :-)

[Jonathan St. Cloud]

1600 ft/m bet the helicopter pilot could have pulled more torque. The 500 I was flying would do 2200 fpm with a load all day

[Bruce Hoult]

On Monday, August 26, 2019 at 1:53:15 PM UTC-7, Ross wrote:

I believe it was also used for at least one outlanding from a very small flat area in a river bed. The chopper didn't need a ground roll, and the glider didn't need much of one.

[2G]

Sounds good: do you post your flights on OLC? My numbers are based on actual flights that you can view on OLC. I really wish my climbs were that good, but they aren't, and that is flying with 21m tips.

Tom

[jfitch]

Numbers are based on IGC log files over 3 seasons. I've written a program that analyzes the log files for climb rate. I don't bother much with OLC. Looking at 31 climbs in the same conditions and on the same day only. a few minutes before or after me, I seem to climb somewhat better (that is a 31-18). The 26Mi is a bit lighter maybe.

[Ross]

I believe it was also used for at least one outlanding from a very small flat area in a river bed. The chopper didn't need a ground roll, and the glider didn't need much of one.

No, the Swiss team would have like to but the team manager said no and the trailer was choppered in