---From which one should take heed to lay in a suitable spares stock of dampers
against that
fateful day 1000 or more service hours in the future when the dampers go and
Hagon is
no more. Should not ANYTHING that is a speciality mechanism should be so
considered?
Shaun
A207
----- Original Message -----
From: "Nigel Graham" <nigel_graham@intercept.com>
<europa@avnet.co.uk>
Subject: Re: Bouncy landings
> When you consider the chronology of the development of the
> undercarriage, it will become apparent why there is probably not an
> alternative (at a price you could justify).
>
> The prototype had no suspension/damping at all - relying on the
> deformation of the tyre for "damping". The Mk1 relied only on the red
> "bounce block" to catapult the aircraft back into the air. To control
> this reaction, the damper unit was retro-engineered into the only space
> available, which was far from ideal.
>
> The mechanical advantage (dis-advantage) is such that the damper has to
> control colossal loads, so high that one unit could not handle these
> loads alone and two had to be used.
> Martin Hagon freely admits that this is the most heavily damped unit
> that Hagons produce and is unique to the Europa.
>
> Since no other auto or motor cycle application (competition or
> otherwise) needs anything like this degree of damping, it is unlikely
> you could find an alternative unit from another supplier - certainly not
> at a price that you could justify. Ohlins are beautifully engineered,
> but I shudder to think what such a unit might cost.
>
> The Europa is built down to a cost (no offence intended, this is the
> economics of profitability) and the Hagon unit is probably the best
> compromise between cost and functionality.
>
> If they fail occasionally, I would simply replace them with more of the
> same.
>
> Nigel
>
>
> ----- Original Message -----
> From: Miles McCallum <milesm@avnet.co.uk>
> Subject: Re: Bouncy landings
>
>
> > The dampers are made by Alf Hagon (we used to call him Ali-Alf) who
> does
> > motorcycle dampers and in my experience the characteristics are good,
> the
> > longevity less so - I wouldn't have used them in my racing days, but I
> would
> > (and do) on the road.
> >
> > There are plenty of other damper manufacturers - Ohlins being
> particularly
> > good, but there are others up to the task: it's a case of matching
> length,
> > stroke, diameter where it matters,fixings, and damping to the
> originals (in
> > good shape) - you will probably be able to specify adjustable
> compression
> > and rebound damping, and gas pressurised with a remote reservoir would
> be
> > better for a variety of reasons.
> >
> > However you definitely gets what you pay for - I'd would guess a set
> of
> > Ohlins to cost more than $500, but then if they last 1000 hours
> (before
> > rebuild - unlike the hagons) and you can tailor them to really suit
> your
> > style (!) it would seem to be worth it.
> >
> > Miles
> >
> >
> >
> >
> >
> >
> > ----- Original Message -----
> > From: "Terry Seaver" <terrys@cisco.com>
> > Subject: Bouncy landings
> >
> >
> > > A few weeks ago my build partner, David DeFord,
> > > and I were out doing some pattern work and were
> > > having problems with our landings. The plane was
> > > bouncing rather badly, even on what would usually
> > > be considered a good touch-down. We later
> > > removed the main gear shock assembly and
> > > inspected the dampers. We had borrowed
> > > a pair of new ones from a fellow builder, and
> > > compared them to our old ones, which have
> > > about 100 hours on them now. Our old ones
> > > felt the same as the new ones, but we noticed
> > > some oily fluid at the bottom of one.
> > >
> > > We replaced the old dampers with the new
> > > ones and then went out to check the landings.
> > > The bounce was gone, the dampers really
> > > work well.
> > > I just hope our bad one was an anomaly,
> > > not the norm, as this could get expensive,
> > > at about $250 every 100 hours or so (not
> > > counting the half day it takes to replace them).
> > >
> > > Has anyone else had this happen?
> > > If these do wear out this fast, is there
> > > an alternative damper that might last
> > > longer?
> > >
> > > Terry Seaver
> > > A135 / N135TD
> > >
> > >
> > >
> > >
> > > The Europa List is supported by Aviators Network UK -
> info@avnet.co.uk
> >
>
>
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