Glider towing with a Varga Kachina 2180

V

Vargapilot

Filing Flight Plan
Joined
May 7, 2012
Messages
2
Location
Switzerland
Display Name
Display name:
Vargapilot
We operate with two Vargas in our gliding club SG Zürich in Switzerland. Now we have problems with the Federal Office of Civil Aviation and the EASSA. The certification was done a long time ago. The weight of a glider was not so high 30 years ago as today.We are only allowed to tow till a max. weight of 580kg. Does anybody know the allowed weight of towing gliders and banners by a Varga Kachina 2180, does anybody know the right person or department by the FAA to ask? Thank you in advance for your support.
 
does the factory still exist/support this type? There is nothing on the US type certificate about towing (not surprising) and I don't find any STC's in the database when I search "varga". I suspect that if there are any in the US that are towing gliders, they had a hook installed via 337.

Typically in the US there are not glider weight limits associated with the towplanes airframe, instead there are rope breaking strength limits associated with the towhook installation. My understanding is that usually with Tost releases there is basically no limit usually and the Schweizer hooks usually have a 1200 lb max breaking strength.

The 580 kg number had to have come from somewhere. Is it in the flight manual or part of extra paperwork that came with the tow release installation? Perhaps it was the heaviest 2 seater in production at the time or perhaps it was the max that the factory engineers were willing to certify.
 
ok here is a page with pictures of the drawings for glider towhook installation. Is this the kind of hook you have? http://vg21squadron.com/data.htm This is a typical Schweizer towhook installation, almost exactly the same as a tricycle gear Cessna. The 1200 lb load limit is standard on Schweizer hooks and I believe it has to do with release loads.

In the USA, your best bet to get a higher limit in this case would be to get a form 337 approval to install a Tost hook. You would probably have to prove that the structure was good enough to withstand the higher load.
 
Thank you Toni for your information. Your are right, at that time, the glider with 580 kg was the heaviest. Our Vargas are very poular for towing, specially by competition as they can tow the haviest gliders very well. But the papers do not match to our experience. We are going through the FAA registration to get in contact with owners of Vargas.The from 337 means a major change by the EASA and can be made only by two special factories in Switzerland. The costs are so high, as we have paid for the Varga. If we find a Varag in the USA, which is officially allowed to tow more weight, we can do the process much cheaper. Do you know an airfield on which they operate with Vargas? We are not sure, but in north carolina, it should have an airflield where they do towing gliders with Varags. Thank's for further support!
 
Vargapilot said:
Thank you Toni for your information. Your are right, at that time, the glider with 580 kg was the heaviest. Our Vargas are very poular for towing, specially by competition as they can tow the haviest gliders very well. But the papers do not match to our experience. We are going through the FAA registration to get in contact with owners of Vargas.The from 337 means a major change by the EASA and can be made only by two special factories in Switzerland. The costs are so high, as we have paid for the Varga. If we find a Varag in the USA, which is officially allowed to tow more weight, we can do the process much cheaper. Do you know an airfield on which they operate with Vargas? We are not sure, but in north carolina, it should have an airflield where they do towing gliders with Varags. Thank's for further support!
Click to expand...

If they're in North Carolina, we should have someone with the info from them but if Tony is correct about there being a 1200lb (545kg) limitation on the STC'd/Field Approved hook then you already are beyond what they are allowed on the normal hook so you'll need a plane rigged with a bigger hook and due to the cost and relative rarity of Vargas in the US that roll is typically filled by higher powered small agricultural aircraft.
 
I've actually never heard of anyone towing with a Varga in the US but that doesn't mean that it isn't possible.
 
Henning said:
If they're in North Carolina, we should have someone with the info from them but if Tony is correct about there being a 1200lb (545kg) limitation on the STC'd/Field Approved hook then you already are beyond what they are allowed on the normal hook so you'll need a plane rigged with a bigger hook and due to the cost and relative rarity of Vargas in the US that roll is typically filled by higher powered small agricultural aircraft.
Click to expand...

1200 lb is the limit of the rope strength. US Rules allow the rope to be between 80 and 200% of glider gross weight, so with a 1200 lb breaking strength rope you can pull up to 1500 lb (680 kg) glider. I have no idea what the rules are in Switzerland.
 
tonycondon said:
1200 lb is the limit of the rope strength. US Rules allow the rope to be between 80 and 200% of glider gross weight, so with a 1200 lb breaking strength rope you can pull up to 1500 lb (680 kg) glider. I have no idea what the rules are in Switzerland.
Click to expand...

So that's max gross possible to design a glider for in the US, 1500lbs? Because the defined legal limit of the rope is restricted to 1200 lb most of which it will never see?
 
no, all new open class gliders are designed for the maximum allowed contest weight of 850kg. They just can't be (legally) towed by airplanes with a Schweizer hook that is limited to 1200 lbs. There are towplanes with Tost hooks installed which as far as I know have no max rope strength limit, unless it is set by the structure of the towplane.
 
The 1200 lb restriction is a Schweitzer tow release mechanism restriction. It has nothing to do with the strength of the rope being used. We changed over to a TOST release which has over 1800 lb maximum limit. The tensile strength of the rope used has to fall within 80 to 200 percent of the MGOW of the glider and the glider has to be below the maximum weight limit for the release being used.
 
Last edited:
huh? the 1200 lb load limit on the schweizer release limits the rope strength to 1200 lbs. otherwise what would 1200 lbs refer to?
 
tonycondon said:
huh? the 1200 lb load limit on the schweizer release limits the rope strength to 1200 lbs. otherwise what would 1200 lbs refer to?
Click to expand...

Max Gross Operating Weight of Glider.
 
tonycondon said:
huh? the 1200 lb load limit on the schweizer release limits the rope strength to 1200 lbs. otherwise what would 1200 lbs refer to?
Click to expand...

Wait a moment please, could we back up a minute and get a definition on this please? Are we talking loaded breaking strength or are we talking weight of the glider?
 
the 1200 lbs is the maximum allowed load on the hook (i.e. max rope strength), not the max weight of the glider. there is a big difference.

as this page of the drawing for the Varga shows, the max allowed load is 1200 lbs, not the max glider weight.
towhook_5b.jpg


The Cessna drawing that I can find for 182's through 207's says "Minimum strength of towline not to exceed 1200 lbs"

http://www.wingsunlimitedtowhooks.c..._thru_207_Schweizer_Tow_Hook_Installation.pdf

I guess I must stand somewhat corrected as the drawing for the 150, 152, and 172 refers to glider gross weight. 1200 lbs for 172 and 817 (?) lbs for the 150 and 152. I wonder if thats a typo. http://www.wingsunlimitedtowhooks.c..._thru_207_Schweizer_Tow_Hook_Installation.pdf

The other Cessa documents from that site don't say anything about rope strength

Citabria drawings have a placard with 1200 lb max breaking strength
http://www.wingsunlimitedtowhooks.com/pdf-files/Citabria_Schweizer_Tow_Hook_Installation.pdf
 
tonycondon said:
the 1200 lbs is the maximum allowed load on the hook (i.e. max rope strength), not the max weight of the glider. there is a big difference.
Click to expand...

Big difference is right unless you're picking it straight up, that's why I was wondering how a 1200lb breaking strength line limitation worked out to not being able to to gliders over 1200lbs.

The 817lbs may be a rivet quantity/strength issue in the tail.
 
Last edited:
i've heard that the 817 lb limit had something to do with pulling the tail off, yes.
 
You must log in or register to reply here.
Back
Top