Greetings Gentlemen, I am quiet concerned about the ending of Mazda
rotary production and would like to see the Mistrel type av engine
fitted with a compound turbo system as per Pauls' CAD drawings.
Nothing short of brilliant!
We have just finished price negotiations on a Seawind 3000
incomplete amphibian kit which we expect to take delivery of next
month. We will be installing a 20b Mazda on it with a compound turbo
system. Yet to be engineered. Quality reference from anyone having
the needed knowledge in turbine sizing/design would be highly
appreciated.
All the manifolding/mountings will be scratch made in house. We have
located blade producers to handle blade assemblies. I grew up in a
family run machine shop and have 25 years as a Plant Engineering
Technician. Efforts are now moving forward on obtaining ample
funding for an additive machining center to produce honey combed
interior shaft assemblies and end covers to further reduce weight and
bring production costs down. 100 pounds of Monel reduced to 27 pounds
of shaft leaves a lot of time and material on the floor!
We also have a huge existing residential market use for an
affordable 45 hp rotary with a blow down turbo. Which we will not
disclose for engineering with out an NDA. $5,000 for an Axiro is more
than a bit much!
Cheers Ya-All, Michael Nash
Michael, A word of warning on the seawind, they are a real dog to
fly. Having that engine up there on the tail is a bad idea, they
suffer badly from gyroscopic precession when rolling into the turn. A
good friend of mine here killed himself trying to take off from a
lake, he hit a boat wake (not a big one) and it porpoised and dove in
killing him. They can only handle a very small choppiness on the
water. I flew it a few times and boy did it need a lot of rudder
input to co-ordinate in a turn. Changing power settings on final for
landing was a disaster, the pitch changed dramatically with throttle
change. Just my 2 cents worth here
Michael. Chris in NZ.
With the CG that high I can see how that might happen. Any
significant impact at water level will cause a pitch down.
Paul Lamar
Thank you for your informative words...they have in fact pounded 15
of these into the ground. The slowed prop does in fact impede airflow
over the elevator and rudder control surfaces particularly on final.
We had seriously thought about moving the 20B down into the aft fuse
and using carbon fiber drive shafts and magnetic couplings for low
friction loss to solve the GG issue. The high speed wing lacking lift
is the other demon. A Retractable hydrofoil to keep the nose up and
clean might help. Thank you for the "Heads UP" You caring words did
not fall on deaf ears. I think we will take it to the company that is
trying to sell a certified version Seawind and let them work to save
their bacon. I won't mind helping them work it out especially if it
saves lives down the road. Respectfully, Michael Nash in Virginia
I would lengthen the hull. You need more buoyancy forward.
Paul Lamar
I can't speak to this design specifically but the high thrust line
of this style of aircraft scares me silly. The most common time for
an engine failure is take-off. A high thrust line like this tends to
push the nose down during high power applications which must be
compensated for. On take-off and initial climb you are at low speed,
high A of A and close to the surface. If your engine loses power for
even a second it can be enough to take that thrust line (nose down
moment) and reverse it into a very high drag line (nose up moment).
This puts you way past the critical A of A where you have no chance
of recovery, I knew a couple of people who sadly learned this in the
last few seconds of their lives.
John Gibbons
Interesting thoughts as to the Seawind. I remember it at the Oshkosh
seaplane base. It came in with 4 people... left with one. It just
can't get out of the water well. Perhaps some of you remember the Air
Shark. Much like the Seawind, it tried to be "fast".. In fact, may
still hold the speed record for a single engine monohull amphibian of
over 200 mph., but.. it too came in to the seaplane base to prove
it's worth. It was eventually beached and trailered back to the
airshow. Couldn't get out of the water. It of course no longer
exists. Amphibious monohulls of a smaller nature are a compromise.
The engine has to go somewhere on top... usually a pylon. The Lake
Amphibian is I believe the only certificated of that genre. The
bigger monohulls of course aren't as affected by said thrust lines
with the engines in the wings. The Grumman Goose and Mallards out
there etc... and even the twin Seabee's. These attempts at faster
amphibians (personally), just don't have enough boat under them. The
compromise to being faster. (?) It's always (The Seawind) been a
beautiful bird... and fast. Just probably shouldn't be an amphibian.
One to watch perhaps is the French Lisa Akoya... Basically, a mini
Seawind. (with "Seafoils" instead of a stepped hull) They too are
struggling for certification as an LSA. Some might say any aircraft
can be a widow maker, but.. amphibians given their versatility and
use in water likely score right up there. Good luck with your Seawind
Michael.
Bruce Buksyk
Hi Guys,
I'm adding my words of support to those who are adding their words
of wisdom of using an extra dose of caution for known problems in
aircraft that are flying out there, and thoughts of both improving
existing designs of aircraft and engines, be cautiously aggressive.
Those are not mutually exclusive terms or traits to follow.
Just as it takes many ingredients and skills to make something
simple like good ice cream, it takes many, many more to make a good,
but very complex, safe engine/airplane combo, more input from
everyone directed into making these projects safer will benefit
everyone, present and future. For those who don't understand the
relevance of this analogy, World famous Blue Bell Ice Cream of
Brenham Tx. Just this week accidently killed three customers because
of a very minor error in the manufacturing process of a well proven
product.
Let's all of us do everything possible to help those who are doing
all they can to make better safer aviation products.
Paul, Thanks for the work you are doing. What time and days are your
forums at "Sun and Fun" ?
Fly Safe,
Larry (Flash) Gordon Houston Tx
My schedule is :
Wankel Rotary Engines in Experimental Aircraft
Tuesday 1:00 room 10
Multi Strike Capacitor Discharge Ignitions for high RPM Wankel
rotary engines
Wednesday 1:00 room 10
Universal Motor Mounts for Mazda rotary engines.
Thursday 1:00 room 10
Paul Lamar
If you want a twin engine composite amphibian, look at this one:
http://www.gweduck.com/ I would absolutely love to have one of
these!
Steve Brazil
Steve,
What about building a kit version of the Dornier Seastar
<
http://www.dornierseaplane.com/ <
http://www.dornierseaplane.com/
scaled down to a six seat with twin centerline Mazda 20B engines in
place of expensive Turbo-Prop engines?
Now that would be one fine design, and cost would not be
prohibitive...
G. F. Curtis Jr
G. F. Curtis Jr, et al,
Indeed there is a great sexiness and appeal to these designs. But I
would argue they are not in the least practical as a business
proposition. They are indeed cost prohibitive. To use some recently
quoted figures, 2-20B at 75 % power would be eating fuel at a rate of
around $300/hour. Even at half that, it would put the cost way out of
reach of any sort of sales number that could be marketable.They would
be a one, or two of design. It would be cheaper to buy certified and
learn to live with whatever compromises your choice brings with it.
Typically an aircraft of this size would need to be operated
commercially to justify the costs.
It seems to me there are a disproportionately high ratio of people
this group that can say "Now that would be one fine design, and cost
would not be prohibitive...". On a regular basis, these "fine design"
ideas come along, and they are great ideas, don't get me wrong, but
for the most part they don't lead anywhere . Where we see progress in
getting rotaries in the air is in the 13B size, and they are by more
or less regular guys, Brian and Dave etc. IMHO the next likely
breakthrough in ACRE usage is the opposite end of the spectrum where
the more economical to run engines can capitalize on the rotaries
ability to be small, light, economical and efficient. The market for
Richards single rotor would be a hundred times the size of the market
of a fire breathing 20B. Diamond (? Rotax ?) has one ready to go
though, so why aren't they selling yet ?
Now having said all that, if I do win the lottery, a lot of that
money would go into a PP, turbo compound 20B Harmon Rocket style
plane that would be the envy of the list. :)
John Gibbons
Diamond (Austro Engines) has sold over 500. The customer loves them.
Paul Lamar
I've always liked the Grumman Amphibians, particularly the Goose and
the Widgeon but they are a lot of airplane to feed. There is one
reasonable amphibian that that hasn't been mentioned here and that
is the Republic Seabee:
http://en.wikipedia.org/wiki/Republic_RC-3_Seabee
<
http://en.wikipedia.org/wiki/Republic_RC-3_Seabee Robinson builds a
conversion kit to put GM LS v8s in them:
http://www.v8aircraft.com/
. The man who designed the Seabee, Percival Spencer, also designed
the Spencer Air Car:
http://en.wikipedia.org/wiki/Spencer_Air_Car
<
http://en.wikipedia.org/wiki/Spencer_Air_Car I think if I wanted an
amphibian, and I wanted to get in the kit airplane business, I would
redesign the Spencer Air Car in composite with a few improvements.
The three rotor would do very nicely in it.
Steve Brazil
The Gweduck is apparently available in kit form now. All composite,
but otherwise a conventional configuration reminiscent of the
Grumman amphibs. I've never flown one, but did get a chance to look
over the prototype and watch it fly. On the face of it, it seems like
a reasonable candidate for high output engines.
Merl F. Raisbeck
Wants,wishes and dreams are cheap,may as well have the best of all of
them... A rotary with compound a turbo system whether 1,2,3 or 4
rotor with finely vaporized fuel and a Cap based MSD ignition (That I
just heard about!) will reliably produce 200 hp per rotor and be very
affordable to produce with 3D print additive machining. Hydrogen
injection just before TDC produces a 60,000 fps flame front on any
engine resulting in a very clean burn and a small increase 2-5% in
hp. A Mazda can melt almost any exhaust system. BMW found that
Toluene worked very well capturing exhaust heat and fed it into a
turbine without the formation of liquid droplets on the turbine
throwing it out of balance. A 3rotar Mistral produces 196,000 BTU's
according to their info.
My wish list for the Seawind: 3 rotors at 500 TO HP. using the above
mentioned sub systems. Turning 2 counter rotating props. With a CVT
to slow engine rpm at cruse. (50-60% power at high prop rpm) +200mph
cruse Lower the engine pylon maybe 12in. to take advantage of the
smaller diameter props to lower the thrust line. Talk to the Synergy
folks to put on a double box wing. Raising the lift center of effect
above the current arrangement. Put all control surfaces out in clean
air. Air brings airplanes off the water...add more low drag wing
length and stronger air movers. Larger flap/ailerons to increase wing
in ground effect and manage high CG polar roll moment. Yeah I
know...Just throw money and time and it's yours. Not only do I think
it is doable. I believe it should be done. Aren't dreams and wishes
great!
Michael Nash
A smaller prop is less efficient. Worse MPG. Also much less static
thrust and sea planes need a lot of static thrust to get on the
step.
Paul Lamar
I do not think you would want to use a CVT for a PSRU. They are
still kind-of experimental. Ford developed one for use in the Flex
with all wheel drive in conjunction with ZF. ZF pulled out half way
through development and told Ford not to continue with the project.
Ford said they had too much in it to quit then. Dropped the CVT in
that unit after 2 years, and went back to a conventional auto trans.
Expensive and reliability issues. They MAY be ok if used in low HP
low performance use. People with a more sporty driving style or
heavy foot tend to have problems with them. High duty cycle use in
an aircraft will strain the capabilities of a CVT. They also suffer
from the same problems Paul describes for spur gear drives. Heavy
duty truck transmissions have two or three counter shafts to
distribute the load and help "float" the output and input shafts to
reduce load on individual components. Not viable in an aircraft due
to the weight. Car and light truck manual transmissions last due to
low duty cycle. If the duty cycle was increased to 75% to 100% they
will wear because of the side loading on the bearings and the small
contact area on the gear teeth. Eventually the metal fatigues and
the surface starts to flake off. Noisy and then total failure. CVT's
work something like a snowmobile drive. A rubber belt between two
pairs of cones. As the engine revs up the drive pair get pushed
together which pushes the belt toward the outer diameter and the
driven pair are spread so the belt runs close to the small diameter.
Sleds have a holder for a spare belt and tools to change it when it
fails in use. Just cheap and light. CVT's use a steel belt and I
believe a friction drive oil. Can't change that in flight!!
Dale Davies
Thank you all for the concise recap of past trials and short falls
of applied technologies. I will be happy to settle for a 2 speed:
TOHP and cruse with a governor to inhibit prop over speed.
Accomplished by: 2 planetary PSRU's in one housing with a hollow
shafts sharing a sliding shaft with 4 or 6 detente balls to engage
one set or the other. Obviously we are talking heat treated Monel and
all scratch made. I expect it would gain near 100 % in weight of the
Ford based unit.
All just a thought I would like to pursue with someone that likes
working machine torque/ load equations. My mind also sees a hyd
clutch disk between rotors 2 and 3 on a 20b and 26b. (run only what
you need) I grew up in a very successful family machine shop and
retired as a Plant Engineering Tec. for Coors at age 44 in 1999.
I am currently arranging the capitol to pursue these projects. Which
includes a shop to produce rotary engines run by my boys. My
favourite activity is to add to the quality and capability of the
people around me. This is my second wind and hopefully a legacy.
Respectfully and hopefully to your collective benefit, Michael Nash
I would not fuss about a two speed reduction unit. Build a 3.12:1 PSRU as
Paul has described. A rotary engine will TO at 7500RPM no problem providing
the right prop. It will have no problem running all day at 6000RPM cruise
and LOP.
If you want to machine things, work with Paul to build the power
recovery he has been working on to drive from the compressor side of a
turbo.
Once the power recovery is built it can be used on a 13B, 20B or
Renesis. Best place to devote time and $ to improve power output and fuel
economy. If you still want to build a PSRU, a hollow shaft to use a
hydraulic constant speed prop may be a project. There is at least a couple
being designed with probable production already by people on this site.
Give Paul a couple of days to get back from Germany and then send a note
marked private as he has been on top of a lot of things here for a number
of years. He can give you an idea then on how to proceed.
Dale Davies
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