With reference to the NSI and Arplast VP props - I have now flown 7
aircraft ( 4 Europas , a KIS, Kitfox 5 and an RV6) fitted with the NSI
prop. and must admit that I do not find the work load greatly increased
over the fixed pitch prop.
Most of my flying with the VP prop. has been in Europas fitted with the NSI
EA-81 engine and apart from greatly reduced take off run and increased rate
of climb, the other major benifit is cruising at much lower engine speeds (
typically 3800 rpm @ 130 kts) which equates to much lower fuel burn ( 3.9
gal/hr), lower noise level, better cooling, less engine wear and less pilot
fatigue.
The NSI VP prop. has reverse (Beta) facility as standard but for the Europa
we fit a Fine pitch stop set to allow the engine to pull max. power rpm in
the climb, ie. 5800 rpm for the Rotax 912 and 5600 rpm for the NSI EA-81.
Normal operating procedures are to set fully fine pitch for take off.
After take off - gear/flaps up and increase pitch to reduce rpm to around
5000 for climb out ( or leave fully fine if max. climb performance is
required).
When level at required altitude increase the pitch to fully coarse ( 25
degrees Rotax, 30 degrees NSI) as the aircraft accelerates and regulate
the speed with throttle as with a fixed pitch prop.
The pitch is reset to fully fine during the landing checks as with a
C/Speed prop. in case of a missed approach.
The prop.is controlled by either a switch on the panel and/or buttons on
the MAC stick grips.
Performance with the 100hp EA-81 is as follows:
Top speed : 140 Kts +
Cruise speed : 130 Kts @ 4000 rpm - 3.9 gal/hr
120 Kts @ 3700 rpm - 3.3 gal/hr
R.O.C.: 1200 ft/min (solo)
1000 ft/min (1370 lbs)
Take off run : 150 m (solo)
200 m (1370 lbs)
If anyone has further questions, I will be pleased to help.
Ivan has tested most of the available VP props. on the market so is able to
give an unbiased opinion.
Melvin Cross
----------
> From: Jerry <jerry@flyinghi.demon.co.uk>
> Subject: Variable pitch propellers
> Date: 13 July 1997 21:53
>
> As a main player you all should know my position.
> Etiquette means I shouldn't advertise and indeed I don't want to.
> Not here anyway, but I would like to pass on what little knowledge I
have.
>
> I note Bill said the VP greatly increased cockpit workload.
> I actually flew behind the Arplast VP for the first time at Cranfield.
(on
> the Dyn Aero Ban-bi)
> Dyn Aero had the main control on the panel and slave controls on both
> control sticks, on MAC grips.
>
> I have to say I didn't find the workload too bad but yes it is another
> thing to think about and I'll continue to suggest Europa ( and other
pilots
> ) start with a normal prop and go wobbly once they are happy with all the
> other controls. Apart from anything else a standard prop is much cheaper
to
> stick into the ground than a wobbly.
>
> Most noticeable effect will be on the take off and climb.
> It allows the full potential of the engine to be used.
> There may be a small increase in top speed (not more than a few kts in
our
> experience)
> You can use a lot less RPM in the cruise which may reduce engine wear and
> will certainly reduce engine noise and pilot fatigue. Fuel consumption
> though is unlikely to change much.
>
> A lot of pilots have asked about servicing.
> It is not expected that there will be any official notice relating to the
> Arplast at least.
> I should think it would be the same for the NSI.
> After lots of experience a sensible service schedule will be adopted (I
> suspect different for each type of prop).
> Parts that have shown signs of wear in high hour installations will
require
> replacement at agreed periods.
> The Arplast prop can be stripped down by the owner who if he has built
his
> own aircraft should be capable with his inspector to carry out
anticipated
> checks and overhauls.
> For those who don't want to we will probably be able to do it for them.
>
> Of course I'll be delighted to answer any questions on the Arplast VP
prop.
>
> Jerry
>
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