Paul I respectfully disagree. One of the biggest troubles for some
systems, like a 20B
RV-10 will be the lack of a CS prop. That is saying that a fixed pitch
won't work at all
but carrying enough pitch for cruse/top speed will lengthen takeoff
distance by a
significant amount.
Bill Jepson
Not if you start with a p-port 3 rotor. How many RV10 out there have 375
HP?
Paul Lamar
I also disagree about the need for a PRSU that will handle a CS prop, but
when I looked at the Variprop website, its only rated for 300hp. If a NA
20B P-Port will make 375hp (not sure about that), I'm not sure it would
hold
up. Certainly the 20B P-Port will make more that 300 hp in any case. I
think the greatest need is for a PRSU that will take a CS prop. At this
point, everyone just has to settle for what we can get and hope for a new
product!!
Don
Don,
I'm in total agreement with Paul that a P-port 20B will make major HP. In a
talk with
Daryl Drummond he said you would have to intentionally hold it back to make
only 300!
I agree that it would be best if the CS could be a light one. Senstitch
(sorry I never
could
spell their name right) Is doing a new all composite CS. Egg Subaru has
been selling them.
They have several blade configurations. Just a possibility.
Bill Jepson
Hi Paul,
This may be a good time for a survey. IE Everyone who would pay XXX dollars
MORE to have Constant Speed Prop Capability---line up here. Everyone who
is
positive they will Always Be Content with Fixed Pitch ----line up here.
Even if a builder never uses the capability of the hollow shaft, he/she may
want it simply to enhance the aircraft value at resale time. The big
question is "How Much???" There is about a $5000 difference between a CS
prop and a Fixed pitch, and a Governor can be bought for around $2000
rebuilt. These are investments you can chose to make OR CHOSE NOT TO MAKE
if you have a hollow shaft. If you have a solid shaft this option is not
available. I've been very intimate with Tracey's gearbox and have not yet
found a way to adapt it to a CS prop that I would feel comfortable flying
with, so I believe a "clean sheet" design would be approiate.
I have also
watched your Rhino renderings for PSRU's. I have no feel for how much
more/less your new designs would cost COMPLETE, but for the most part I
cannot see where a hollow shaft vs solid shaft should cost more than around
$500 dollars differential. Most of that differential is simply in the cost
for large bearings which seem to get exponentially more expensive with size
increase. The two big costly problems a CS PSRU must overcome are bearing
size/life and seals which must now retain high pressure instead of just
drain pressure. A fair survey would have to account for the additional
cost, but I think the results maysurprise you.
Dave M
It is not just the price and extra weight of the PSRU. Constant speed props
are not cheap. They are in the category of $10,000. Mark S is apparently
rich :)
Paul Lamar
Paul,
I used the savings from installing a rotary engine vs. Lycosarus. I had
money left over even after buying a C/S prop. ;-)
Actually, like I said, I got in on a group buy. Maybe there are enough guys
on this list that would be able to get a group buy going. I went through
Jim Ayers, apparently an authorized M/T dealer. Prices are likely higher
now that the dollar is practically worthless.
Mark S.
I know Jim Ayers he is a local guy.
That is true but a lot of people spend way less than $10,000 on the entire firewall
forward. Perhaps the market is changing but it seems to me the biggest attraction for
the rotary is the low price. A bunch of p-ports out there might change that perception.
IMHO you will be stunned when you first fly your p-port 3 rotor :)
BTW The dollar to the Euro ratio has not completely tanked just yet at 1.5 Euros to the
dollar. Apparently the Europeans are having their economic problems too. Of course if we
keep spending like drunken sailors in an Oriental whore house the dollar will
completely collapse and many people's savings will be wiped out over night. I suspect it
will turn around when people completely understand what is happening. I think much of
what has been done so far can be undone so I am an optimist. Professor Arthur Laffer
thinks it can be undone nearly over night. I hope so. Gold price will drop again (I
think) and that is when I am going to buy :) I should have bought it a year ago.
Paul Lamar
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