Today's Message Index:
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1. 11:22 AM - Re: Rotax 914 Dyno Test (rparigoris)
2. 12:42 PM - Flap rigging adjustment rqd (JDA)
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| Subject: | Re: Rotax 914 Dyno Test |
Hi Area 51
Yes you turn off the power to the TCU to lock the waste-gate servo in whatever
position it happens to be in. There is a series normally closed switch in series
with the waste-gate that is a momentary switch, it's used to reset TCU if boost
pressure is rising and dropping. Maximum off of switch is 5 seconds, see
page 4-3.
As far as idle airbox pressure, looking at figure 6 on page 7-10, Rotax by using
the throttle position sensor, closes the wastegate between 0 and 10% of throttle
movement (they are using 115% movement). It's not just the cracking of butterfly
off of idle, it's the TCU opening the wastegate when the lever is at 10%.
10% equates to just about 1/2" in the throttle slot. I'm thinking perhaps
the reason Rotax closes the wastegate, is to prevent carb ice if the airbox was
at ambient pressure with butterfly very closed??? Then looking at figure 6,
they open the wastegate from 10% to a little under 50%.
You were not comparing apples with apples when you said the 914 can only make 74hp
at 5,000 rpm. You were probably looking at performance data for CS prop page
5-4. That shows a 75% (that is of 100%) setting of 31" and 5,000 rpm. 31" is
not the maxium MF pressure, it just happens to be what is required for 75%.
If you look at Manifold Pressure graph page 5-2 and Performance graph for standard
conditions page 5-2, you will see that 100% continuous manifold pressure
and 5,00 rpm horse power is just under 90hp. Using 115% manifold pressure and
5,000 rpm, horse power is just under 100hp.
For a D)178 B take off If the TCU seems to be working, the manual has you have
the TCU on, set 115% power, then turn off TCU. If the TCU isn't working properly,
personally I would just leave the wastegate opened till I could fix it, but
if I really needed to have some extra power, close wastegate then turn off TCU
and CAREFULLY add throttle and take off, then open wastegate and turn off TCU.
Ron
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| Subject: | Flap rigging adjustment rqd |
Does anyone have any advice on adjusting the flap rigging once the initial build
has been completed? My monowheel has slightly more flap (about 1deg) on the
RHS. The upshot is that it rolls left - even with a passenger on board. I have
to carry a bit of aileron to compensate which is easily trimmed out, but because
of this the aircraft always drops a left wing in the stall - and sometimes
quite dramatically! If I stall with the stick in the middle and keep the wings
level with rudder I can sit in the heavy buffet without wing drop. Because of
the benign stick-central stall I am reluctant to use stall strips, although
this remains a last-ditch solution. I would rather fix the problem at source and
level up the flaps - it is only a tiny amount. The Europa Club archives has
some notes by Bud Yerly: he advocates trimming the flaps by shimming the flap
drive tube against the baggage bulkhead to "twist" the tube. However having spent
a day with a torch and a lot of head scratching I cannot work out exactly
how this would work in practice - and in any case there is no bulkhead for me
to easily shim against. It seems to me that it would be a far easier solution
to shim one of the flap drive tube brackets (FL18) on the floor of the fuselage
to raise one side of the tube - if only they weren't bonded in place! My proposed
solution therefore is to obtain a replacement torque tube hinge arm FL16
(undrilled) from Europa, and re-drill the holes to effectively shorten the
arm and drop the flap on one side by one degree. This would cause a little twisting,
but the whole flap assembly across the span appears flexible with a little
play - and we are only talking about 1 deg as measured at the flap which is
a tiny amount.
My questions are: has anyone successfully adjusted their flap rigging before? How
was it done? Has anyone used Bud's solution who can explain how it works in
practice? Can anyone think of a technical objection to my own proposal above?
To answer the obvious question: I am in the UK and subject to the LAA. My inspector
would be involved and I am already sharing my thoughts with him, but neither
of us wants to re-invent the wheel if it has been done before!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=511036#511036
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