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Technical Chat Tips and Advice, including flying the Luscombe

Moderator: HTB

 #9056  by Florian
 Fri Dec 04, 2015 9:38 am
Hey guys,

first of all some explanation where this questions is from....

My brother is a glider pilot for the german junior national team and one day we had some drinks at a bonfire at the airfield and what should I say, we developed an accoring idea.... :cheers2: :drunken:

We got the idea to fit a tow hook to my 8E to tow his glider. When we compared the data of the Luscombe with our clubs AVo68 Samburo touring motor glider which we usually use for towing we figured out that the Luscombe might be able to tow at least light weight gliders like Ka8 or Ka6 and maybe even small single seat composite gliders like LS1 or LS4.

Let's compare the specs...
The Samburo has a 115HP Rotax engine with automatically adjusting two blade constand speed prop. My Luscombe has the C85-12F with the 1,8m McCauly two blade fixed pitch prop. I belive the designator was something like 1B90CM.

Both airplanes have similar climb rates with attention to weight and quite equal cruise speeds. When I am half full (about 12 US gallons / 45 litres) and have only my 150 pound body in it my Luscombe climbes with about 700 ft/min. In tow the Samburo would make about 200ft/min. Even with MTOW I do 500ft/min.

On the Samburo the hook is attached to the tailwhell assembly which obviously transferres the load into the steel tubing of the fuselage. Even if the Luscombes Scott 3200 looks quite capable of dealing with the loads of an attached glider I am not quite sure how the fuselage will behave. As far as I know there are no beams inside and so the skin is taking all the stresses.

I looked with German aviation part suppliers and figured out that a rear mounted tow hook is available for about 500€ plus installation and certification.

What do you think about that idea? Would you say that the Luscombe could be able to tow? O would you call me something inbetween dreamer and stupid idiot? :scratch:
 #9058  by Nige
 Fri Dec 04, 2015 2:46 pm
Well Florian,
I know the Luscombe is a flexible being and towing gliders may well work looking at your figures but I'm out of my depth here. :scratch: Sounds exciting though. Most Luscombes are nose heavy so c of g shouldn't be a problem. Fitting and having the tow hook approved may be a headache though? Good luck and let us know how you get on?

Nige.
 #9062  by Florian
 Fri Dec 04, 2015 7:57 pm
Thanks for that backup. Technically I am almost certain that it is possible to make it work. But as you said, the official stuff... Maybe I should register her as an experimental to get more freedom.
 #9065  by dmcneil
 Sun Dec 06, 2015 6:23 pm
Hi Florian and Nige,

The Luscombe has been used as a tow plane here in the US. In the 1950s and 1960s it was much more common to see low HP tow planes although even then the Luscombe was no doubt a rare sight with a tow hook. One notable Luscombe tow was that used to launch Paul Bikle on his record shattering altitude flight in 1961. Here's a link to his account of the flight including the launch tow behind an 85 HP Luscombe:

http://www.aerosente.com/2009/09/the-wo ... ickle.html

My T-8F was used as a tow plane in it's early days. I believe it was more for banner tows rather than glider tows. There is a field approval in the airplane's paperwork for the tow hook installation... no details, just "tow hook installed". :) This was surely a Schweizer hook. You'd probably want a TOST hook these days.

I don't know of any current approvals (STCs) for a tow hook installation on a Luscombe although there are old ones around (such as on my airplane). We have an approval route available via the FAA AC43.13-2B, Chapter 8, Glider and Banner Tow Hitch Installations. http://www.faa.gov/documentLibrary/medi ... .13-2B.pdf That document may help with approvals from your authorities.

Dan
 #9066  by Florian
 Sun Dec 06, 2015 7:14 pm
Hi Dan,

that sounds awesome!!!! Haven’t looked at the links yet but will do it right after writing this. According to "your authorities" it helps a lot to get FAA data because my authorities are the same then yours. I kept the US registration on that plane. So don't tell it to the german CAA to loudly but I do give a shit on what they think about my baby. :lol: Even without a hook it would never meet the german maintenance requirements. I did no 10h, 25h, 50h, 100h inspection which are about what to do with a 100h commercial inspection in the US. And of course I am no certified mechanic if I check the tire pressure. :shock:


Florian
 #9067  by Florian
 Sun Dec 06, 2015 8:46 pm
Reading done! So far it looks like I could create my own fixture to mount the Tost hitch on the tailwheel assembly and get an FAA field approval.

By the way, do I understand it right that the difference between STC and field approval is that with an STC the FAA agrees to alterations within specified circumstances (eg. aircraft type, part to add/exchange, ...) every time and that the field approval is unique for my single airplane and even if someone else has exactly the same plane and wants to do exactly the same alteration he has to do the field approval, too? :scratch:
 #9068  by dmcneil
 Sun Dec 06, 2015 9:55 pm
Your understanding of the STC vs. field approval definitions is right on. An STC is a supplemental type certificate. Lots of expense and time to get an STC. It's an approval to modify ALL airplanes of the specified model to the specs and configuration defined in the STC. A field approval is a one off for a single airplane.

You should talk to whomever maintains your N numbered Luscombe... the AP-IA who signs off the annual inspections. He/she is the person that would have to submit the field approval to the FAA. You need to get their input on how to approach a tow hook installation.

Hope you can get the tow hook installed! It would be a hoot to do an occasional glider tow.

Dan
 #9069  by Nige
 Mon Dec 07, 2015 2:11 pm
Indeed Dan! Now that would be an awesome sight in our modern world to see!! Fascinating! :shock:

Nige.
 #9070  by Florian
 Tue Dec 08, 2015 1:04 pm
Thanks for that input. My A&P is an IA, too. He also loves vintage airplanes. So I'm sure to get him to help me with that idea. At least so far I have informations that it is gernerally legal and it has been done before. A good point to start with.

When I am on airfield the upcoming weekend I will have a close look to our TMG to get some photos of that tow hook attach bracket to make a first draft of mine and to send that stuff to my A&P.

Florian