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
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 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 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
Speaking of dream amphibians, what about a scale Catalina.
Rotary power of course
https://youtu.be/aFOAbdW-oeo
Phill Hinds
George Town TAS
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