A very quick look at your link tells me that a DA62 performs pretty similarly to the Soloy conversion but burns about 10USG/hr less.
Peter wrote:
Marketing will do what they have always done: turbine → pressurisation.
Not only marketing . It is a simple performance issue. Turbines are effective up high, not low down.
In my perception, the future should center on two technologies: Diesel/Jet A1 for non pressurized airplanes and turbines for pressurized ones. Both use Jet A1 and both are economical in their proper environment. Start mixing them and you are in trouble.
redRover wrote:
Depends on your design spec. Most of the really low energy consumption aircraft have a very glider like wingplan, in that they have enormous high aspect ratio wings, and also operate in a relatively narrow speed range.
For human powered aircraft you need something with a large wingspan because you have only a few hundred watts of sustained power available. If you can build an aircraft that will stay aloft then you’ve done well, no matter what speed it flies at. Likewise for the Solar Impulse – it needs a large wing area to hold the solar panels, and to be able to fly on low power overnight.
Battery powertrains can have a very high power to weight ratio – higher even than turbine aircraft if you don’t have carry too much in the way of batteries. It’s just the endurance that suffers. However, electrified aircraft tend towards two types: self-launching gliders (where you don’t need a lot of endurance) or smaller aircraft such as the CriCri or Luciole with relatively high wing loadings.
If you’re planning to go somewhere, other than ‘up’, a smaller faster aircraft is likely to be more practical, even if electric.
kwlf wrote:
electrified aircraft tend towards two types: self-launching gliders
I’m afraid almost all certified self lunchers use some kind of combustion engine.
kwlf wrote:
smaller aircraft such as the CriCri or Luciole with relatively high wing loadings
in case of MC30 wing loading at MTOW is 43,5 kg/m2. That’s less than any modern fully loaded competition glider
according to my memory electric Lucille can fly for less then 1 hour at 135 km/h, while a “normal” MC30 powered by Briggs&Straton consumes about 8 litres / hour @ 200 km/h. Standard tank holds 30 liters.
Now, what is the cost of those batteries and electric engine? How many cycles before it loses its capacity?
B&S engine is ca. 1000 Euro + VAT and it lasts “forever”, by that I mean none of the Lucioles flying so far accumulated enough hours to experience any sings of engine wear.
Diesel engines are a reality, of course. But as far as adoption they’re still not there. The question is – will they ever be adopted before either we have more capable electric or cheaper turbines? I’m not sure.
AdamFrisch wrote:
But as far as adoption they’re still not there.
Well, there were enough STC’s intitally but first trust in the company fell with the bancruptcy and then there still is no viable 180-200 hp variant.
Robin_253 wrote:
in case of MC30 wing loading at MTOW is 43,5 kg/m2. That’s less than any modern fully loaded competition glider
according to my memory electric Lucille can fly for less then 1 hour at 135 km/h, while a “normal” MC30 powered by Briggs&Straton consumes about 8 litres / hour @ 200 km/h. Standard tank holds 30 liters.
I wouldn’t choose to electrify a Luciole and all your points are well made (though won’t the competition glider be carrying a lot of ballast?).
A while ago I was thinking of building an aircraft, and efficiency was high on my list of priorities. I wondered why the Luciole didn’t look more like a motor glider – after all aren’t gliders the most efficient aircraft out there? The answer was that the priorities are different and if it were to be built with longer wings it would end up heavier and with a higher fuel consumption.
A glider needs to be able to extract energy from the air, which means it needs a low min-sink rate and good glide ratio. A powered aircraft with a relatively poor glide ratio and a high min-sink rate that needs less power to keep aloft will be able to travel further at the same speed on the same fuel. So you have two potential optimisations: glider like, to be operated as a glider, or SEP like to be operated as a powered aircraft.
Diesel has basically failed abysmally, in Europe and even more comprehensively in the USA – except for Diamond who sold the engines because they bundled them in a marketable airframe. The rest of the diesel market (other new aircraft models, and engine retrofits) has gone almost nowhere.
kwlf wrote:
A glider needs to be able to extract energy from the air, which means it needs a low min-sink rate and good glide ratio. A powered aircraft with a relatively poor glide ratio and a high min-sink rate that needs less power to keep aloft will be able to travel further at the same speed on the same fuel. So you have two potential optimisations: glider like, to be operated as a glider, or SEP like to be operated as a powered aircraft.
Surely the important factor here is the min sink rate, not the glide ratio? The min sink correlates directly with the wing loading, which the glide ratio does not.
@peter: we saw a few numbers of diesel enginnes on C172 mostly and even less conversionson the PA140.
From what i have read, there are few concens with reliability of the gearboxes.
I have also been following a few projects of small turbines on the range of 200hp. The major problem is always the certified GA.
