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/ 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
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