>"Be careful what you wish for, lest it come true" ;)
  >
  >So, now, please gentlemen, what components/assemblies would experimental
  >aircraft builder mostly need from us rotary people? - First, foremost,
  >and then nice-to-have...
  >This subject somewhat bloated to kind of "State of the Union"... So
  >please bear with me...
  >
  >Why to ask?
  >Immediate Selfish reasons ;) I have to decide a subject for my thesis
  >work. And besides, there's been so much attention to details that i'm
  >not sure of the current big picture, and besides, this is interesting ;)
  >
  >Why to answer?
  >I figured that perhaps i could do something that's both useful and
  >interesting, instead of eg. those wonderful pulp pump dynamics... and,
  >besides, this should be interesting...
  >
  >SO, would you have..
  >
  >Better PSRU?
  >One with provision for constant-speed prop? Lighter? Neater? Cheaper? Or
  >will just having a new kind of bell housing do fine?
  >
  >Better Fuel Injection/ECU?
  >Is Tracy's ECN good enough, or is there still something that needs
  >attention?
  >
  >Better induction manifold?
  >Why? Original too clumsy/heavy? For both 13B and Renesis?
  >
  >Dry sump?
  >Now would that make aerobatic chaps happy?
  >
  >Backplate?
  >A là Mistral? How much would this make difference on engine
mounting
  >ease/weight and on driving accessories?
  >
  >Firewall-forward kits?
  >No-brainer. Of course :) But for what kitplanes?
  >RV-8, Lancair Super II and CH-801 as starters? Paul and Jerry have made
  >a fine work with the mounts, and there's been plans for ducting also...
  >but can we say that it is a FWF kit yet?
  >
  >Turbos that keep together?
  >How bad is the rotary+turbo issue, really? Some fellas are flying with
  >'em all the time, so problem solved?
  >
  >New midblock to get 3-rotor engines easily?
  >20B's rarifying to extinction? How about just biting the bullet and
  >making a usable midblock to get 3-rotor engines again? Why? To have
  >RV-10, Glasair III and Lancairs on menu again!
  >And then the salient point: for 13B or for Renesis blocks?
  >
  >
  >Turbine-performance featherweight 4-rotor Hi-rev P-port compound
  >intercooler wonders that consume almost nothing and cost next to
  >nothing? And airframe to match to break Every FAI record Ever made!!
  >
  >Sure!
  >Why?
  >Becuse We Can!!!
  >
  >But, um, what things should be done first?
  >
  >Cheers,
  >
  >Petri

  >My vote is turbo compound for lower fuel burn.
  >
  >Paul Lamar

What I want is a reliable, inexpensive conversion kit for the 13B to a
single-rotor, with adapter plates to mount it to the Notax 2-stroke
mount and Provision 8 gearboxes -- in other words, to yank the 2-stroke
out from between the mount and PSRU.

Keith

My input,
A low cost, light weight PSRU with plenty of HP headroom that can handle
a CS prop by design. The Mistral design looks great but I've been told
that they don't want to sell parts anymore. Tracy's is low cost but
lacks any provision for Hyd CS. After taht I would be interested in
turbocompound.
Bill Jepson


Bill,
I gave up on having the casting house that was working on our stuff. I am
currently looking for a new source in northern ca, so if you know anyone,
let me know. I have picked up the molds for the bell housing, as they never
got around to casting it for us.
So mistral is not selling parts.... guess that leaves the door wide open...
Larry

Too bad they used to do good work for me until they apparently were
taken over by a new owner or something.

Paul Lamar

Too bad indeed.
Larry, I would love to work with you on a PSRU system. Since Fancois' is
on the ACRE list perhaps he would tell us something different. I know
that my e-mails have gone unanswered. I know that they are trying to
promote their own engine, but I would think that they would like to make
their position clear to the list since we are likely to be their biggest
supporters. I will be check on the foundry situation. I know there is a
foundry at Mather Air field , formerly a military base. I'm not sure if
it went private.
Bill Jepson

Fancois is no longer president of Mistral.

Paul Lamar

Bill, Larry,

If there is any interest I would be willing to have a 3-D scan done on
the 3:1 Bell PSRU unit parts I have.  It is only 140mm long but very
robust.  The only design challenge will be in re cutting new planetary
gears to better fit high speed needle bearings. It would be easy to add
an option for hydraulic C/S as the central shaft is three inches but I
share Dave's opinion that electric C/S props are now accurate and fast
responding.

 It could interface with the new Bell housing Larry designed quite
easily. Several  additions  I would recommend however on the bell
housing.

One,  A central boss if casted into the bell housing design would
function as a good place to mount a bearing.  Why?  To support any side
loads imparted on the sun gear shaft in case it is used to belt drive
accessories.

Two,  An oil channel be casted (later line bored) into the housing to
feed the central bearing and PSRU.

Three,  The housing designed with several side opening to allow
inspection of entrance and exit of accessory belts.

The RX-4 semi automatic housing I have already has all of these functions
but it may or may not be what you are looking for.

I also agree with Dave's assessment of the front housing mount.  Many
years ago Racing Beat did make a front housing that I have personally
seen on Dave Garber's plane.   This allowed several magnetos an
alternator, and starter motor to be inserted from the back side.  The
water pump I am working on would also benefit from this arrangement. I
don't know for sure but I am assuming all accessories were gear driven
much like what you would find on a Lyc. or Continental.

A drawback?  Housing and gears  might  be heavier than pulleys and belts.
 More reliable though.

In any standard rear mount, the lower mount is in compression which is
fine for the housing but the upper mount is in tension as the engine CG
is far forward.  Our engine is a sandwich construction and if it is all
aluminum engine we might be subjecting the engine to additional stress,
in hard landings.  I would installed two 12mm dia. tension rods
extending up to catch the rear housing behind the bell housing to
distribute the loads near the CG. These rods would run at  the upper
quadrant of the engine and not interfere with intake manifolds.


Doug in Japan

Nobody is going to be able to afford a copy of the Bell 47 gearbox and it
is way overkill anyway. There is no beating mass produced automotive parts
when they do the job. Rotaries are not about torque. They get the HP with
RPM. High speed needle bearings are an oxymoron :) Hydraulic CS metal props are
much cheaper and more efficient unless there is a thin blade carbon fiber CS
prop out there I don't know about. MT props are not carbon fiber (wood with
glass fiber coating) and they are 20 MPH slower than a metal constant speed
prop. The tips are too thick.

Good point about the stressed engine Doug. I like the Questair engine CG mount
better and Jerry's motor mount welding jig is adjustable over a wide range.

Paul Lamar

Paul,

No  problem with the PSRU.  I made the offer for the benefit of others
out there who share my opinion on gear ratios and aero quality parts.
Make that caged roller bearings although my catalog calls them by both
names. Yes of course I agree the engine is designed to produce power at
high rpms.  so why limit it with a low ratio PSRU just because the parts
are mass produced and cheap to come by?   Come on! That is an option
sure but I am willing to bet the rotary will never be accepted as a good
aircraft engine replacement until the quality of the parts and
performance exceeds  what is presently on the market.  That means upping
the power to weight ratio.  That also makes cooling (as you have so
often stated) the biggest obstacle in the way of going for the gold.

For PSRU design the Bell may seem over kill, its not. In stock form it is
a 1947 gear set designed to transmit huge rotor torque loads at 300 rpms
max.   Changing it to operate with 660 lbs of torque loads and 8,000 rpms
inputs is no walk in the park either and has resulted in every bearing
and shaft redesigned.  Nice magnesium conical housing and ring gear is
the only nice thing I can say about the unit.   To use it I still have
to create a strong bell housing. On the other hand look at the
engineering that went into Mistral's robust unit, both in gears, gear
profile, bearing support, bolt pattern, and conical shape.  Over
designed?  Perhaps for my use but it will hold up to the most severe
acrobatics.  Drive ratio is too low IMHO but there is enough room inside,
to change that in the future.

Putting my businessman hat on, I believe Mistral has started down the
right path.  Unfortunately they are missing out on an immediate
homebuilt market and that means a cash flow as well as market feedback
on design and therefore rapid improvement.  Perhaps they are not
confident in their products yet or concerned with the bad PR if someone
crashes with their engine.  Shouldn't be in this line of business if
so.   As a business model they can sell their products to a rep in USA,
Australia or where ever and let that rep. assume the responsibility or
builder assistance to self built aircraft owners.   Their PSRU and front
housing may not readily fit but I am willing to bet with a little
modifications their rep or purchasers can make it so.  People who build
aircraft have great networks in engineering expertise.  Of course there
is no guarantee we actually listen to them, self included:)

On a high quality and performing unit check out Aero Composites, carbon
fiber props. Only offered with a hydraulic hub when I checked 6 months
ago.

This is the first time I heard MT props are slower. Where did you find
that information?
SeaWinds fly using metal Hartzell or MT,  both with top speeds
approaching 200mph.  I have never heard bad things about the performance
of these props.  Perhaps at higher speeds the effect occurs?


Doug in Japan

My hangar neighbor Tracy Saylor, with the fastest RV6 in the world
at 238 MPH, tried the MT back to back with the metal CS prop he was running.
Lost 15 MPH as I recall. Makes sense when you look at it closely. The efficiency
of a prop is closely correlated with the thickness of the tips. His theory was the blade was twisting due to the lower modulus of elasticity of wood compared to aluminum but I am not so sure. The tips consume most of the HP as they are going the fastest and account for the majority of the drag. The MT has rather fat tips out of necessity. If you go to Reno you will find all the really fast airplanes are using metal props or carbon fiber. The metal props outnumber the carbon fiber props ten to one. Of course both Hartzel and McCauley probably put a lot of R&D money into racing props.

Paul Lamar