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Author Topic: How-to make a safe start with an off centre gravity towhook  (Read 7739 times)

Offline Johan van Ravenzwaaij

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No sweat at take off...

The first series of ASW-15 was delivered with only a center of gravity hook. This hook is placed left of the midline of the plane. This situation causes the plane to go right in tow or winch launch. The latter ASW-15's had also a towhook. This tow hook is also available at Schleicher as a modification kit.

So what to do to avoid the tendacy to make a dangerous groundloop and anticipate to it. Note this situation only takes place at take off when there is still ground contact.

  • Make sure you get briefed by an experienced instructor (or ASW15 owner) about the flight characteristics of the ASW15 before you make your first fligh
  • Is the tail skid installed so it is in line with the fuselage?
  • Start every aerotow launch with the stick fully back. This keeps the tail firmly planted while on initial roll and helps to keep directional control. Once aileron control is felt, release the backpressure and allow the glider to rotate up onto the main wheel. Remember, this all happens well before the glider flies. I would not suggest keeping full back pressure, you might find your aerotow looking more like a winch launch.
  • Keep always your left hand near the release.
  • Brief your wing runner very well and always have them run your downwind wing. It's a hell of a lot easier to slightly hold back than to run forward to keep you straight in a cross wind.
  • If you have any cross wind make sure you start with FULL opposite rudder to counter any swing at towlaunch.
  • At winch launch always start with full left rudder, you're too late to react when the plane wants to break out. After a few seconds you can give less rudder.

Don't get frightened by all of this, it's still a very fine plane to fly. These tips are collected at this website and I want to thank all the pilots for their tips but especially member Wyvern for his help.

DISCLAIMER: The author takes no responsibility for the text mentioned above. This tips should be used at your own risk only.
« Last Edit: 16 January 2010, 20:18 by Johan van Ravenzwaaij »
Conquer the skies with the Gelderse Soaring Club

Offline Peter Mylett

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Re: How-to make a safe start with an off centre gravity towhook
« Reply #1 on: 16 January 2010, 16:05 »
I have just read this article pointing out one of the reputed idiosyncrasies of the Asw15.

For anyone who has not flown an Asw15, I can assure you they are as safe as any glider you will come across.  At my gliding club, a fairly challenging hill site where only winch launching is possible,  we have no less than five Asw15’s and it is regarded as one of the best first syndicate gliders for early solo pilots. 

My own Asw15B has an aerotow hook fitted and a tail wheel. However, we do have the described off-centre (to the left of centre) tow hook used on winch launching. I may be missing something here but this generally means in neutral conditions the nose tends to want to veer to the right and not the left as described in the article ( Hence the contention that full left rudder will counter the swing)?

Further, the advice does not cover the component forces of a winch launch where there is a significant crosswind and/or slope (E.g. Winch Launching at a Hill site) in which case the pull down slope caused by the weight of the cable and/or the weather cocking effect of the wind have an over riding effect that may mean starting with full opposite left rudder, as suggested, could be completely the wrong thing to do?

Can I also suggest that this obviously well meaning article (and I mean neither offence nor disrespect to the authors) needs to separate out and clarify quite distinctly the different techniques appropriate to a winch launch as opposed to an aerotow.  Whilst I know what was meant, as it stands, it could conceivably be misinterpreted by the unwary to mean full stick back and full left rudder is a good tip when starting a winch launch?

((For those in any doubt it isn’t, Image the scenario of doing this when the overriding crosswind and slope forces are likely to swing the nose to the left on takeoff? Your (possibly inexperienced) winch driver is over enthusiastic with the initial power? The glider goes off like a rocket, rotates from the ground with yaw at a steep angle– possible result? – A high speed stall with yaw (which is by definition?) - Yes “A Spin” - in this case vertically on the wire from zero+ feet; a situation from which glider and pilot are extremely unlikely to survive unscathed?))[/ii]

My personal advice to any pilot flying any glider for the first time (and I am not an instructor) is to get a proper briefing appropriate to the conditions on the day from a qualified instructor who is familiar with the type.

Incidentally, the BGA in the UK produce a very good leaflet about the hazards of winch launching generally. It can be found at this link http://www.gliding.co.uk/bgainfo/safety/safewinchlaunching.htm

There are also some  very enlightening  video clip showing the consequences of getting it wrong – well worth a few minutes viewing for any glider pilot (irrespective of experience level!)  – Even if you disagree with every word I have said.
 
Enjoy, be Safe and Happy Landings (and Launches) to All !!
Gliding - The most fun you can have and keep your clothes on !!

Offline Chuck Lohre

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Re: How-to make a safe start with an off centre gravity towhook
« Reply #2 on: 16 January 2010, 18:43 »
I'm glad the second post corrected that the hook is on the left side and makes the ship go right on aero-tow takeoff. Sometimes when there is a bit of wind I cant my ship to the left and leave the left wing down on aero-tow takeoff. If there is little or no wind a left hand wing runner works well. Likewise I'm not an instructor and I agree with the comments about getting preflight advise from an instructor familiar with the type.
Chuck Lohre, 6V, chuck@lohre.com, 1-513-260-9025

Offline Johan van Ravenzwaaij

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Re: How-to make a safe start with an off centre gravity towhook
« Reply #3 on: 16 January 2010, 20:08 »
Hi Peter and Chuck,

Thank you boys for the input. As this how-to is a work in progress I will implement your advices; if anyone has some more tips on this matter please post here as a reply.
My own Asw15B has an aerotow hook fitted and a tail wheel. However, we do have the described off-centre (to the left of centre) tow hook used on winch launching. I may be missing something here but this generally means in neutral conditions the nose tends to want to veer to the right and not the left as described in the article ( Hence the contention that full left rudder will counter the swing)?

You couldn't be more right; I will change this right away.

Cheers Johan
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Offline Tom

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Re: How-to make a safe start with an off centre gravity towhook
« Reply #4 on: 16 March 2016, 01:01 »
Having hundreds of launches in the 15 the Method described works well. The 15 is not a problem to get in the air and wonderful to fly

 

person