>>snip<<

My thoughts are this, although Greg's "no wastegate" approach worked

for him,

if instead you go the wastegate route and use an adjustable boost

controller,

although more expensive and complex to install, it adds an extra margine of
safety to the system and at critical times may be one less thing to monitor
and control. Going without means settling for "best guess" and I'm just not
one who is comfortable with that ambiguity.
Any thoughts, ideas, criticisms or advice?
...Chrissi

Since you asked, Devil's advocate here.  P-)
After thinking about the no waste gate layout Greg used I've developed an
appreciation for it.  This comes from some failure mode analysis (strictly
armchair stuff).  OTOH Continental Lycoming, et al, have went with waste
gates most likely to reduce their liability, not increase it.  The round
engine drivers of old had to watch the MP and know what kind of fuel they
took on last so they could set the throttle properly for take off.  Flying
by MP was part of the job and from the perspective of this old piston
(ahem) head, it keeps you in tune with your engine's performance. You may
have already considered the following.

Waste gate = added complexity and failure modes:
Does it fail open?  That is if you are on takeoff at Leadville, CO, on a
hot August afternoon at full gross, will you get out of ground effect and
over the obstacles at the end of the runway?
Does it fail closed?  If you are not in the habit of watching your MP as
you firewall (nose cone wall??) the throttle while departing Copper Hill
International in the winter, will the engine survive?

Like I said, armchair analysis, I'm going NA 'cause a turbo won't fit in a
RV-4.   P-)
Mike McGee
Control Systems Engineer

Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode

All good points Mike. If I had some hours in Greg's plane I would have a greater appreciation for
his modality. It makes sense to me,  just iffy if we can hit the selection on the nose first time.
That I don't like.
Yeah I know, welcome to EXPERIMENTAL AVIATION.
...Chrissi

 
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