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
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