Practical aircraft for everyday use -concept

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Tiger Tim

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1. Design and test high speed composite amphib floats for the Diamond.
2. Put in production somewhere.
3. ?
4. Profit.
 

karoliina.t.salminen

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Yup, very close to the SkiGull mission. Be patient and someday it may be available as a kit (but not by Burt according to past statements he's made to the public). BTW it can be Prius efficient when you consider straight-line travel (usually about 40% less distance). I was in the chase plane for SkiGull 1st flight and in about 2 hours of flying it only burned about 2 gallons of fuel since we were going slow.
Yes, I think the SkiGull is the closest match all over to these requirements. Also knows these requirements are fairly realistic as there is a flying example of that already in existence.
The efficiency of SkiGull would probably be acceptable level compromise and the SkiGull otherwise (with the long range and all) would be more useful than just commuting this route,
more useful and practical than our Diamond in fact in multiple ways. It would be interesting if SkiGull would be a kit-plane or plans built plane. If the kit price is reasonable and not skyrocketing
like today's Lancair prices which make very little sense vs. purchasing ready-made certified aircraft.
 

Kingfisher

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Just an observation: Your strict "pass/fail" fuel burn limit ("no more than a Prius") may significantly increase costs/decrease utility in other areas of the design. There may be value in doing a tradeoff analysis in this criteria.
I agree with that. If people start to commute through the air, which I'm convinced will happen very soon, this will mean another increase in energy consumption of the human population, at least initially. Drone -like vehicles are more likely to be small and nimble enough for the job, but will obviously be less efficient than a Diamond or Prius. Maybe the Joby S2 or something similar will boost efficiency and may be practical if it folds up small enough. However, like commercial air travel, this extra energy consumption is acceptable, if the trade off in time savings is good enough, after all time is money.
I thought the amphibian thrown in there was a good idea for places like Finland or Alaska, even Midwest of USA, if fun is a factor. However if one can make multi-copter ideas work, these can be flown by anyone without flying skills to most accurate positions and will make water landings unnessecary.
 

Tom Nalevanko

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No simple aircraft can fly safely in all weather and fog.
So as the title requests, there is a problem finding any aircraft for everyday trips to work. Would the boss allow days off for fog?

Seattle's Seahawks Jimmy Graham is recently famous for flying his seaplane to work. His Dehaviland Beaver is hardly practical. Largely a stunt. I doubt anyone else flies to work every day. http://www.seahawks.com/news/2015/06/03/seahawks-te-jimmy-graham-flying-high-new-nfl-home

A flying car makes more sense because you can drive it home when foggy instead of being stuck for two days in a seaplane.
Cars also have a problem with weather and fog; and all those other cars on the road. I started my career in aerospace in the 70's in the LAX area. At Hughes Aircraft in Culver City, they had the world's longest private runway. The CEO and good buddy of Howard Hughes, Pat Hyland, regularly flew in his 172 from his ranch and parked it next to his office. Many aero-engineers flew their planes to neighboring airports like KHHR, KTOA, KCPM and KSMO. In the same era when I visited Boeing in Renton, a few of the managers would land their tailwheel aircraft in a big, usually muddy field, next to the plant. So the planes exist; it is the lack of will, talent and financial ability that may be masking this...

Blue skies,

Tom
 

Glider

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Cars also have a problem with weather and fog...
I will disagree with that position.

I have variously made my home in SoCal (oil-water problems after rain), SF-BA (fog), Philadelphia (unbelievable rain | white out conditions, feet of snow), DC (hurricanes, unbelievable rain | white out conditions, feet of snow), Boston (unbelievable rain | white out conditions, feet of snow), SE Alaska, Bumble, Germany (white out conditions & unbelievable icing, 2-3" thick, and hard as rock, after 6-8 hours), and a country that had frequent and strong sand storms (black out conditions).

Never have I had any difficulty going, on a whim, from A to B in a car. After I was licensed, I'd intentionally go driving, on the primary roads and interstates, during a popup "Snow Emergency" to practice, and gain experience, in driving in dangerous conditions, and be in the presence of others who may not have been up to the challenge.

Cars have no problem in any driving I have done; it is the drivers who have the problem.

I've been in a L-23 glider, with a CFI-G as PIC, when, during a moderately windy day, while flying through rotors after TO, we could not stay in control behind the towplane, and had to release, and return to the field (none in the club flew afterward).
 

karoliina.t.salminen

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Yes, Joby S2 would be perfect. However, Joby S2 is not available. Joby S2 is a good tradeoff, especially because it uses electricity and not fuel. The price difference between
electricity and fuel is extremely significant, especially in AVGAS which costs 3.5 euros per liter and is generally not available except in EFHF that is going to be probably closed.

The extra consumption of energy in electricity is very inexpensive. Plus the Joby S2 is efficient, I would bet that the little minimal nacelles will not ruin the
aerodynamics of the wing and their negative effect will be negligible. The only problem is the energy storage. The battery density is going to double with
lithium sulphur batteries and these are almost product ready, but the doubing of energy density is not enough for good electric planes. The battery density
should double at least two times before battery alone is a good energy source for a plane.

The efficiency increase by increasing the wing span is not exactly very expensive if we consider cost of materials. The spars need to be stronger and the larger wing area will require more carbon fiber and epoxy.
However, the long wing is not exactly the biggest cost of the airplane. I would bet that the difference of cost between e.g. DA40 AR=10 wing and sailplane AR=20 wing is negligible in price when the aspect ratio and span is purely considered.
The more carbon needed of course costs more but even if the carbon is very expensive, it is still not gold.

The higher wing loading of the plane than sailplane moves the cruise Cl towards L/D maximum (as the higher the cruise Cl, the higher the cruise L/D is) and also helps in windy/turbulent conditions. Of course high aspect ratio is more sensitive than low aspect ratio, but the higher wing loading should make a difference between this and sailplane. The fuel consumption is all about cruise L/D.

About weather: the days when the weather is not VFR, there is always the Prius (or hopefully Tesla in the future) in garage for that. We already have got the good IFR plane which the DA40 is.
The IFR flight is not suitable for short haul work commuting as flying the procedures takes large portion of the time quota to win car. Also with IFR flight comes the navigation fees and the
requirement for landing on airport with instrument approach procedure. This means landing far away from the destination. Therefore nullifying the advantage of speed the plane has.
Also in Finland IFR operations from uncontrolled airfields are not permitted and there are no approach procedures for them, further nullifying the advantage of IFR commute.

About driving in poor weather: We have snow every winter here and driving in "snow emergency" that is not "emergency" in "dangerous conditions" that we are used to is common everyday practise.
Pretty much winter anyway can not be used for flying even with IFR machines because any cloud has from moderate to severe icing conditions. Car use in the winter time is always unavoidable, there are only
few such days on winter when plane can be used safely. Winter flying therefore is not very important consideration because it is potentially unsolvable problem.

Kingfisher: I like the multicopter VTOL approach but there are some problems with it which are not so easily solved. The plane is going to need like 1000 hp to takeoff. Tesla is close to that amount, but
the Tesla battery pack is not exactly very lightweight, this boils down to the problem of the energy density in the battery. Even the lithium sulphur battery is not going to solve this, even better energy density
would be needed that it would be practical. Of course the forward movement can be arranged with series hybrid, but the problem is this:
- To have high enough C-rating for the 1000 hp VTOL takeoff, the battery pack is going to be heavy in any case
- If the batteries are drained in takeoff and forward flight is done with series hybrid, in the forward flight there is the penalty of up to hundreds of kilograms of batteries
that is required for the 1000 hp VTOL takeoff and landing.

My opinion is that VSTOL is going to be much easier with hybrid than VTOL still for some time. There is then this unlucky thing:
landing the seaplane to the sea is no problem. Landing the VTOL in urban area is a problem. It is not permitted and not going to be permitted in very near future.
There are not enough helipads for landing the VTOL craft.

Edit:
The WIG/hovercrafts are not any kind of solution because the sea is a different place than a lake. There is a little river/stream in between, but I can not see it suitable for anything else than padding.
Following that to sea might also make the 80 km trip to 200 km trip.
 

Vigilant1

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Until you do the math. Than it's actually a very good idea that makes a lot of sense...
That online calculator did the math, so it was easy for me. It is an interesting concept.
Pressure vessels nowadays are plenty light. A simple high-pressure airflow pumping water via a venturi would even obliviate the need for on-board water storage.
That's likely a significant improvement. The whole volume of the pressure vessel will then be available for the compressed air (= more available stored energy in the vessel), the mass in the aircraft is lower (=less hydrodynamic drag during acceleration), and probably better ability to tailor the impulse curve using the venturi/nozzle to optimize V of the aircraft at the end of the thrust period.
So, would we get more thrust from this venturi/nozzle approach, or using the compressed air to power a mechanical pump or prop (in the water)? Pneumatic motors are reliable and relatively light.
 
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Sockmonkey

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The WIG/hovercrafts are not any kind of solution because the sea is a different place than a lake. There is a little river/stream in between, but I can not see it suitable for anything else than padding.
Following that to sea might also make the 80 km trip to 200 km trip.
I was thinking you would drive the hovercraft over flat land to to the sea rather than following the river. You did say the terrain is level.

Pneumatic motors are reliable and relatively light.
This makes me think that a pneumatic motor for a self-launching sailplane would be ideal. Much better than electric. Pneumatic systems run relatively cool so the motor itself could be mostly carbon fiber with metal bearings. Plus you can run the air hose wherever you want so the motor could be placed in the ideal location.
 

karoliina.t.salminen

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I was thinking you would drive the hovercraft over flat land to to the sea rather than following the river. You did say the terrain is level.
Yes the terrain is fairly level. However it is full of trees...
Finland is a place where there are trees all over.

This picture illustrates the landscape of Finland: https://2.bp.blogspot.com/-s6mNb4DS408/V9-xnTl9SnI/AAAAAAAAEwM/2WTWce1Jx5cdX8jANIGYyE8ZMrwdoxrawCLcB/s1600/12916792_10153562670792916_2014036555202172930_o.jpg

There are fields in countryside but they are smallish and they are not connected but they have forest in between.
Basically cities, towns and villages and fields are islands in the continuous forest that covers the whole land. There is no contiguous open space.
 
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Sockmonkey

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Yes the terrain is fairly level. However it is full of trees...
Finland is a place where there are trees all over.

This picture illustrates the landscape of Finland: https://2.bp.blogspot.com/-s6mNb4DS408/V9-xnTl9SnI/AAAAAAAAEwM/2WTWce1Jx5cdX8jANIGYyE8ZMrwdoxrawCLcB/s1600/12916792_10153562670792916_2014036555202172930_o.jpg

There are fields in countryside but they are smallish and they are not connected but they have forest in between.
Basically cities, towns and villages and fields are islands in the continuous forest that covers the whole land. There is no contiguous open space.
Ahh, I see. A lot of places around here look just like that.

In terms of actually performing the job, unless you have a lot of money to spend on refining the design and building it, I think you will have to compromise on the efficiency if you want to do all the other things you require.
My own suggestion would be a tandem wing seaplane like the one I posted on the first page. I'm no engineer, but that sort of tandem requires fewer design compromises to make it a seaplane than any other type I've seen. It's also naturally capable of STOL.
 

Autodidact

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Prius fuel economy appears to be 50 mpg at least? This seems impossible to me, am I wrong? You'd need to burn 1.5 GPH @ 80 MPH and about 21 hp. Seems difficult, especially for an amphibian.
 

Vigilant1

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Prius fuel economy appears to be 50 mpg at least? This seems impossible to me, am I wrong? You'd need to burn 1.5 GPH @ 80 MPH and about 21 hp. Seems difficult, especially for an amphibian.
She says she wants 110 kts minimum cruise speed, and wants to use "no more fuel than a Prius, which burns 4 liters for a 100 m trip". At that minimum 110 kt speed, a plane will take 0.54 hours to make the trip, so a max allowable burn rate of about 2 GPH. At a BFSC of .48 lb/HP/hr, that gives us 25 HP to work with. That's within the realm of possibility (Strojnik's "Laminar Magic" went that fast on similar HP). That plane set a record, so it's not easy to do, even taking off from hard ground.
But we'd need some trick to get off the water.
Unless there's some flexibility on the "fuel" (i.e. equivalent fuel >cost< to Prius, which opens up the use of electricity/batteries, the burning of dried reindeer poop, etc) and/or there's some trick to get airborne, I don't think the requirements can be met.
 

BBerson

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Cars also have a problem with weather and fog; and all those other cars on the road. I started my career in aerospace in the 70's in the LAX area. At Hughes Aircraft in Culver City, they had the world's longest private runway. The CEO and good buddy of Howard Hughes, Pat Hyland, regularly flew in his 172 from his ranch and parked it next to his office. Many aero-engineers flew their planes to neighboring airports like KHHR, KTOA, KCPM and KSMO. In the same era when I visited Boeing in Renton, a few of the managers would land their tailwheel aircraft in a big, usually muddy field, next to the plant. So the planes exist; it is the lack of will, talent and financial ability that may be masking this...

Blue skies,

Tom
Yes, you can fly to work if you work at an airport.
But most don't, and the weather is worse in most places other than Southern California.
I think more "practical" commuting might occur with autonomous aircraft that fly safely in fog without any pilot action or knowledge needed. But we are not there yet.
 

BBerson

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That online calculator did the math, so it was easy for me. It is an interesting concept.

That's likely a significant improvement. The whole volume of the pressure vessel will then be available for the compressed air (= more available stored energy in the vessel), the mass in the aircraft is lower (=less hydrodynamic drag during acceleration), and probably better ability to tailor the impulse curve using the venturi/nozzle to optimize V of the aircraft at the end of the thrust period.
So, would we get more thrust from this venturi/nozzle approach, or using the compressed air to power a mechanical pump or prop (in the water)? Pneumatic motors are reliable and relatively light.
A steam rocket was successfully used to jump the Snake river canyon a few weeks ago.
Steam should have more stored energy than compressed air.
http://newatlas.com/eddie-braun-rocket-bike-jump-snake-river-knievel/45477/
 
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Sockmonkey

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A steam rocket was successfully used to jump the Snake river canyon a few weeks ago.
Steam should have more stored energy than compressed air.
The amount of stored energy is a function of pressure, which is only limited by the strength of the pressure vessel. It's the density of the steam when used as reaction mass that makes it more effective for propulsion. The more massive the stuff that you spit out the back is, the more efficient it is at turning your stored energy into forward momentum.
In rockets the stuff you spit out the back to propel yourself is not always the same stuff that generates the force used to spit it out. In the previously mentioned water rocket, the compressed air the power source and the water is your propellant.
In an ion engine, batteries or a nuclear power source generate the force with a magnetic field to spit out ionized gas which is the propellant. Conventional liquid-fueled rocket and the steam rocket are actually oddballs in that they use the same substance as both propellant and for generation the force to expel it.
 

BJC

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The amount of stored energy is a function of pressure, which is only limited by the strength of the pressure vessel.
Stored energy is not a function of pressure alone. The relevant measure is the enthalpy of the system.

Consider a tank full of water at room temperature that has been pressurized to, say, 6000 psi. It has very little energy, and, if breached, does so without explosive force. That is why high pressure vessels are hydrostatically pressure tested to verify integrity. However, heat that water to a temperature sufficient to generate a phase change (water to steam) when the pressure is suddenly reduced, and get a big bang when breached.


BJC
 

Sockmonkey

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Stored energy is not a function of pressure alone. The relevant measure is the enthalpy of the system.

Consider a tank full of water at room temperature that has been pressurized to, say, 6000 psi. It has very little energy, and, if breached, does so without explosive force. That is why high pressure vessels are hydrostatically pressure tested to verify integrity. However, heat that water to a temperature sufficient to generate a phase change (water to steam) when the pressure is suddenly reduced, and get a big bang when breached.
I was thinking more in terms of potential pressure but yeah, I should have accounted for the phase change in my post. My bad.
 

bmcj

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While these don't exactly meet your design needs, they should get you to work and back quickly and cheaply and land in a parking lot rather than on water. That should make the commute more efficient.

https://www.youtube.com/watch?v=9kxu543VwlA
I was scared for him a little bit while he was taxiing, trying to spin up the rotor by hand while moving between the hangars. Why take your attention away from steering a path clear of the buildings just to get a few RPM's on the rotor that early in the game? I would be more inclined to lock the rotor fore and aft and taxi out undistracted, then with the time saved by a faster taxi, I could spin up the rotor faster at the run-up area.
 
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