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Glider Towing

little pat

little pat

Registered User
Port Lavaca, TX
How many people here tow gliders with a PA-18?

I started towing this weekend. Since making the worst decision of my life in 2013(selling the cub) i finally found a way to fly a super cub....and for free! I might be a slave now though. any thoughts?

Also, for those who do tow gliders. When the glider releases and I dive to the left I routinely see 125mph It seems ok. One time I saw 120mph indicated and decided to slip to see what happened (because I was only getting -1,500fpm). It produced a fabric whipping in the wind noise which caused me to immediately stop slipping. What is the fastest speed you have ever slipped.

PS: commercial parachute jump plane pilot told me "only 120mph?? your a wimp."
 
What comm jump pilot uses an 18? One jumper? He's probably using the prop to dive an old pilatus straight down. Once a bird dog rolled over and split-s'd after release, right in front of me. Not sure I would try to emulate these guys.
 
WhiskeyMike said:
The cylinder shop will love to see you coming.
Click to expand...
Actually it’s perfectly OK to put the nose down and go fast as long as you don’t pull the power off. I have quite a few tows in Pawnees and a couple in my 12. After glider release I roll the trim all the way nose down. Then start monitoring rpm keeping it under redline. The idea is to put one heat cycle on the engine. I usually descend at the bottom of the yellow arc and maybe do one 360. I maintain our two Pawnees and haven’t had to pull any cylinders. (1,400 combined hours on the two Pawnees)
 
I towed gliders with a PA-18A-150 for about 10 years. Once glider releases, I'd do a split S to the left and loose about 300-500 ft with airspeed getting up to about 120-125. Once level after the split S, go into about a 60 degree bank 2G turn and you will get about 1500 ft/min down. All this while holding at least 2100 RPM. Maintain at least 2100 RPM until cylinder temps are well below 250, usually about the time you are downwind. Downwind is the only time you will be level, so that is where you want to check your fuel gages! Depending on how far away from the field you are you may not want to do the steep turns to loose altitude. Rapid cylinder head temp changes will cause cracks. If you keep the power up, you won't have problems. I think I ran one engine about 3000 hours and never had a cracked cylinder. We finally pulled the engine when it spun a bearing at close to 9000 hours since overhaul.

Some advise, get to know the glider pilots and their skill/ability! A glider too high on initial tow can KILL you. I lost a good friend that way. Always know where that release lever is! Ours was set up so you didn't even have to grab for it, just move your left leg back off the rudder pedal and you could hit the release with the back of your leg. If you are using a 150HP Cub, performance with a heavy glider isn't very good. Learn to thermal while towing. Again, within the ability of the glider pilot. I had a couple guys that I could turn about 45 degree bank in a thermal and they would stay right with me. Others, (especially new students) you would just fly straight lines and 15 degree bank turns. Don't go downwind, and keep the glider where they can always get back to the field. Watch your airspeed while towing, about 60 with Schweizers, and 70 -75 with glass. If they have water, maybe even 75-80. Most places use High tow. This is less efficient, and more dangerous to the tow pilot. Low tow is much better, but getting the glider guys to recognize this is next to impossible.
 
Do not confuse rpm with power. You can dive at red line rpm with the throttle closed. There will be no heat generated for a gradual cooling of the hot cylinders.
 
skywagon8a said:
Do not confuse rpm with power. You can dive at red line rpm with the throttle closed. There will be no heat generated for a gradual cooling of the hot cylinders.
Click to expand...

Agreed! You gotta keep the power on so temps come down slowly.


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All the oil drops are still in the slipstream. Low tow puts you just below the slipstream. Besides, wouldn’t the oil make that piece of fiberglass a little slicker. ; )


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I have a few tows from the front end of the rope and few hundred of tows from the back end of the rope.

Best advice on becoming a great tow pilot is to become a competent cross-country glider pilot first. You may learn a few things about flying in the process too.

Having flown gliders at a club that required low tow I can say getting towplane oil on the glider was not an issue in low tow.
 
Yeah I noticed you have to thermal to gain any altitude with the heavier gliders...I havent even flown a glider yet, but I am learning just by towing.

How about slipping at 125mph. was I about to die. Logically to me it shouldnt matter how fast you are going other than the side loading on the fuselage. I think the fabric whipping sound was actually the aileron cable flapping against the fabric...
 
little pat, welcome to the fun. My glider towing mentor was Dave Johnson, who started the tow operation at the "old" Black Forest Gliderport near Colorado Springs, and became the tow contractor for the Air Force Academy in the 1960's. After a few billion tows, and lots of cracked cylinders, David C. came up with the following:

Do NOT!!! Split-S off of glider release, just turn left to clear rope and tackle, throttle back, "some" like maybe 2300 rpm, then stomp FULL bottom rudder away from whichever wing tank you're feeding from (feed from TOP tank--think about it), pitch to 80-85 mph IAS, never more, and continue turning descent in slightly nose-high slip at 59 degree bank. Throttle around 22-2300 RPM, unless prop restriction. What this does is minimizes airflow through the front of cowl, while keeping enough power going to minimize shock cooling. Roll out on downwind or base, flaps BELOW 80 mph IAS. Then smooth, gradual throttle reduction to clear fence >200', then close throttle. This should yield >1500 fpm down, while keeping cylinders reasonably happy. Dave eventually developed Field Approvals for 180 hp 0-360's, which his son-in-law Mike Jensen got STC'd, which is a whole 'nother story, but this procedure worked for both 150 and 180 hp Supercubs. Many went well over 2000 hours, except for some which used welded and reworked cylinders, and ham-handed tuggies who forgot to switch BOTH mags on after start....

One of the BGA clubs subsequently did extensive data logging on 'cubs and Pawnees, monitoring CHT. They're very different critters as to cowling and cooling, Pawnees tolerate airspeed better, but don't like to slip as well. But in both cases the initial 30-60 seconds was critical: The big takeaway was SLOW cooldown in compliance with Lycoming Service Bulletin specifying NO MORE THAN 50 degrees F cooldown per minute (I learned to count seconds in the Cubscouts...). These days, you really MUST have all cylinders monitored for CHT, with a shock-cooling alarm, just don't fall into what I've called the "Controlled Flight Into Display" fallacy: Your attention should be mostly out of the cockpit.

The biggest issue I see with new tuggies is grasp of what some of the training operations call "situational awareness": A broad sense of everything going on around, with a view to safety.

And give a big shake-an-howdy to your Sheriff Bobby Vickery from cubscout, eh?

Thanks. cubscout
 
Little Pat,
Where are you towing out of? I know Refugio has a cub and was looking for tow pilots. Fairly active group from what I have been told. Flew an old Schweizer out of there one time, several years ago. Good thermal activity there in the winter. Jon
 
You got the Sherrif right....

i am towing with the refugio soaring club using their cub. ... N3984Z lycoming O-320
 
One of their IAs is a friend of mine. Bob Williams is a good mechanic and has helped keep their aircraft in the air for quite a while. I think he has recently cut back on the amount of work he will be doing on their planes, to work on his C172, and a Stinson project of his own. Give him a howdy, he's a good guy. Jon
 
Reading this, I seem to have a different idea what a "split S" is.

Please educate me for that term in glider speak.
 
Yes I was also wondering about a PA-18 rolling inverted and pulling out of the second half of a loop, perhaps a lusty wingover that goes past vertical is what they mean?


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Wikipedia: Roll inverted, pull. Yes, some tug pilots like to do this. Immelmann's are the opposite, pull inverted, roll upright.
 
Glider initiates the maneuver by releasing the tow rope from the glider. Once the glider pilot is assured the rope is released a 90º turn to the right to clear the
towplane.

After the glider releases the towplane flies straight for a bit followed by a 90º turn to the left. No aerobatics.

I am sure some have done Split S maneuvers on glider release but I have not seen it. My soaring experience is limited to Eastern US, England and Australia.
 
Last edited:
CubScout speaks logically and reasonably - and from experience. Not that I ever in my lifetime screwed around with an airplane, (I swear it wasn't me) but as a business owner, good - consistent- operational practice is a must. Otherwise maintenance and accidents will put you under. Then no one gets to have any fun.
 
Since I started the discussion about a split S after the glider releases, let me elaborate. In a commercial operation with less tow planes than gliders wanting to fly, it is imperative to cycle each tow as quickly and safely as possible. To do that requires thermalling while towing, and descending as rapidly as possible within the limits of engine cooling. Standard towing practices require the glider to make a right turn after release, and the tow plane to make a left turn after release, thereby creating the fastest separation of the glider from the tow rope. After visual verification of rope separation, simply start the left turn, and continue the roll until past vertical then maintain positive G and come out what is essentially the back half of a loop. The entire maneuver can be done at 2G or less, and looses about 500’ of altitude quickly with speed build up to somewhere in the 120 - 125 mph. Follow that with a steep spiral and you see descent rates in the 2000’ per minute down. That’s the only way you can get 6 tows an hour out of a 150hp Super Cub. This is not the technique I use with the Pawnee. I’ve done something on the order of 25000 tows doing it this way. I know it works.


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DGA Pilot I understand exactly what you mean. When I come back down after Skywriting missions from 10,000 or higher, I have a lot of altitude to lose. The spiraling works well. What I was getting at is un-necessary abuse of the engine and airframe, and I've seen a lot of it. And a lot of cracked jugs. I'm not picking on anyone in particular, and I'm always willing to be the subject of criticism - often enough deserved.
 
WhiskeyMike, not abusing the airplane is key. Controlling the cylinder tens so they cool at about 50 degrees a minute keeps them from cracking. A coordinated 2G spiral puts less stress on the airframe than slipping it down at high speed with all the turbulence and buffeting. In those 25000 tows, I didn’t change a cylinder. We finally pulled the engine at about 9000 hours due to a spun bearing.


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6AD36E0D-8440-4951-9EAF-FB38B81EA88F.jpegI tow gliders with a Dave Johnson built PA-18 180 Delivered to the Dublin Gliding Club in Ireland in a shipping container in 1979. It’s still going strong.
 

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Agree that learning to fly gliders helps your skills (I'm a CFI-G).
Towed a lot behind a Pawnee, currently tow with an L-19.

Lots of really good advice above.

Cannot emphasize enough being aware of what the glider is doing. If *any* doubt, cut them loose (release your end of the rope). Big accident (I think in California) a few months ago, when a glider got high on tow, and got into a position that the towplane could not release, and put him (fatally) into the ground.

I think towing is a lot of fun, and satisfying to do well (finding lift, being efficient).

Hope you enjoy it, and stay safe. (Remember, they are always trying to kill you....)
 
chadden said:
Here is a short clip courtesy of the British Gliding Association demonstrating the winch launch effect of a glider ballooning too high behind a tow plane

https://members.gliding.co.uk/wp-content/uploads/sites/3/2015/04/1430311954_aerotow18.mp4

A tug pilot caught out by this effect needs at least 800’ to recover from the upset. These sort of incidents generally happen in the first couple of hundred feet and sadly are usually fatal for the tuggie.
Click to expand...

This also points out the difference between tow hitches. While the Schweitzer hitch is simplest and perfect for use on banner planes a glider tug might be way better off with a TOST hitch because It is possible to release the tow line if the glider veers off at an extreme angle of tow, high, low or to the side. If the tow line is pulling up sharply on a Schweitzer hitch it can be difficult or impossible to pull the release.
 
The bible for glider towing advice

little pat said:
How many people here tow gliders with a PA-18?

I started towing this weekend. Since making the worst decision of my life in 2013(selling the cub) i finally found a way to fly a super cub....and for free! I might be a slave now though. any thoughts?

Also, for those who do tow gliders. When the glider releases and I dive to the left I routinely see 125mph It seems ok. One time I saw 120mph indicated and decided to slip to see what happened (because I was only getting -1,500fpm). It produced a fabric whipping in the wind noise which caused me to immediately stop slipping. What is the fastest speed you have ever slipped.

PS: commercial parachute jump plane pilot told me "only 120mph?? your a wimp."
Click to expand...


https://members.gliding.co.uk/wp-content/uploads/sites/3/2015/04/1430311946_aerotownotes.pdf
 
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