There must be some advantage to being a pusher; tough to maintain laminar flow over a fuselage with a tractor prop; also if it is pressurized and they are looking at performance at 30,000 feet, then perhaps that helps.

OTOH - there are an enormous offsetting number of aircraft announcements that are usually composted to fertilizer that sound just as promising as this does. Moller, Moller, is Moller here? The lack of simple span, L/D, or other typical aerodynamic facts that are usually released increase the odoriferous level.

500 hp, say 350 kW. Likely mass is of the order of 1500kg empty, call it 2500 kg laden, so L/D=350000/(2500*10*200)=14 so not ridiculous. However 4500 miles at 4 mpg is 1080 gallons of fuel.

So rework the above

3500000/(6500*10*200)=37. The average of 14 and 37 is 26, which is getting up there towards glider territory, and almost exactly the same as U-2

Mr Breguet needs to get involved, to refine that number.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

GregLocock,

I cannot find a weight specification anywhere for that thing. 1500kg is a Piper Aztec, with a never-exceed speed of 277mph. The Cessna Citation Mustang is described as a "very light jet". It has performance fairly equivalent to the Celera 500L, it's pressurized, and it's 4000kg.

Sticking with the Cessna...

Power = Force × Velocity = 2×6500N × 630km/hr × 1000m/km × 1/3600hr/s = 2.3×10⁶N.m/s (or W).

2.3×10⁶N.m/s × 1/4.45lb/N × 1/.3048ft/m 1/550HP.s/ft.lb = 3000HP.

Maybe maximum thrust is used only for take-off. Those long, thin wings on the 500L look efficient, but the fuselage holds seven more people than the P‑51's does. There has to be more frontal area. Laminar flow only accomplishes so much, especially when Brand X uses the technology too.

--
JHG

like all things in design, there are advantages and disadvantages with everything.

pusher prop … better airflow over the fuselage (and/or wing) but disturbed airflow over prop (remember Boeing's prop-fan of the 90s ? (one thing) they couldn't solve was the airflow over the prop.

There are other prop planes out there (Piaggio P180) … so it's not insolvable. Avanti also has a very smooth OML … fuselage panels are tooled into position and the frames placed to suit. So we can figure fuel consumption with a typical PT6 turbo-prop, then we can figure the improvement a diesel adds ?

The size of the fuselage is awful (for maximising aero performance … another design trade-off.

If this relies on laminar flow wings, be careful … laminar flow works well when it works, but is awfully sensitive to imperfections (remember the ATR42/72).

another day in paradise, or is paradise one day closer ?

rb1957,

I forgot about the Piaggio P.180. It takes seven to nine passengers, so it is somewhat bigger. Empty mass 4000kg. 460mph max. 370mph cruise. 2×850HP turboprops. Modern, highly aerodynamic design and composite structure. Fuel 0.779lb/mile.

Gasoline is about 6.3lb/gallon, so...

1 ÷ .779lb/mile × 6.3lb/gallon = 8mpg.

That actually is not bad. My uncle and aunt had a Pontiac of some sort with a 454ci V8 that did 8mpg, and it was not cruising at 370mph.

--
JHG

The current test airframe doesn't appear to have passenger windows or any of the normal external antennas that I can see (apparently its mostly metal as well), how representative it ihttps://www.eng-tips.com/postedit.cfm?id=8603099&a... of a production airframe is an interesting question in its self. Although ditching the windows and replacing with digital windows would be pretty appealing (weight, maintenance cost, cabin configuration etc).


How long will it take to get to 30,000 or 40,000 ft, the Avanti starts at 3000 ft/min @S.L, the Otto looks more like 1000 ft /min @ S.L(any one think the GW would be under 10,000 lb) oops should have checked the source data, gross looks more like 4000 to 6000 lb. Sea level climb rate is more like 1700 ft/min. The other question is if its so clean, how do they add the extra drag to get a proper descent rate (one that's not to upset air traffic control).

Out of interest the Avanti specs are here
http://www.smartcockpit.com/docs/P180_Avanti-Speci...

so this thing, compared to the Avanti, has 30% the installed power, claims 1/2 (to 1/3) the fuel consumption. More efficient design will get you some of that … but Avanti is a pretty efficient shape. A diesel could be more efficient but you'd've thought heavier. The dream may be intercity flights as cheap as commercial flights … but
1) demand ?
2) network ?
3) off design performance (contaminated stalls ?), icing, …

yeah, but we're all a bunch of "negative nellies" …

another day in paradise, or is paradise one day closer ?

Does Otto Aviation have Jan Roskam working on the design? It seems to have his fingerprints on it (JR did the prelimiary design of the Avanti).

www.sparweb.ca

IF Celera 500...: can be fitted for high quality passenger accommodations/comfort; and if 'design/mission creep' [weight/drag/parasite EE/hydraulic-power, etc] are kept in-bounds; and if crew visibility is adequate with the current window arrangement... without video-camera enhancement; and if crash worthiness/survivability/escape is adequate; and if the single diesel engine is producible-maintainable-reliable; and if there are exterior color selections available... other than snow white; and if exterior lighting can be enhanced; and if the flight control... and other systems [mech, EE-EL-AE, etc]... are robust and durable; and if it has been tested/vetted for a wide range of speed-loads-CG-flutter-etc; and if the structure/systems are tough/durable [fatigue and limit/ultimate loading, free of flutter, etc]... Then it could be a smash-hit with customers and the FAA alike.

It would be interesting to track the flight history of 'N*18WM' on one of the flight-watch/flight-following websites over the last several years... for 'hard-stare' at real speed-range-altitude validation testing.

As was stated on another website... extraordinary claims demand extraordinary proof.

Unfortunately extraordinary configuration aircraft... incorporating many novel aspects at one time... tend to draw peculiar/intense attention/scrutiny from certification agencies… especially intense after 737-MAX.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

Quote (Marcello Truzzi)

extraordinary claims demand extraordinary proof

I didn't know Marcello Truzzi had a website! But he wrote many books. ;)

Everyone, get some perspective. Nothing being discussed here is as ridiculous radical as the Eviation Alice!

I am so disappointed that the Alice battery fire denied the world's aviation community of the dramatic spectacle of a simultaneous cross-wind wingtip-strike, prop disintegration and ground loop.

www.sparweb.ca

SparWeb… sorry slight miss-quote on my part... DANG.

Extraordinary Claims Require Extraordinary Evidence.” –Carl Sagan, Astrophysicist

The elementary rules of logic... that extraordinary claims require extraordinary evidence and that what can be asserted without evidence can also be dismissed without evidence.” --Christopher Hitchens

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

SparWeb,

I posted on the Eviation Alice (thread16-431720: Electric Planes. Why Not?), for pretty much the same reason. Are the wingtips really the best place to put motors? Even the article on Engineering.com is sceptical. The photograph in the Wikipedia article is more believable.

--
JHG

Somehow the Alice evolved from having a tricycle gear to a prototype with tail-dragger landing gear. So these days with few examples of such an arrangement, the likelihood of an unfamiliar pilot doing a ground loop is very high. Combine that with the engines on the wingtips - the chaos that would inevitably result...

In the rush and excitement to make a marketable EV aircraft, basic aviation is being forgotten. These creative designs are eye-catching, but they also speak to a market that wants to buy because it's new and broadcasts a message, especially when parked in the hangar, not so much because it's a good quality aircraft.

If I were a private pilot, or for example a flight training company, and was offered an EV aircraft that operates for 1/2 the hourly costs of an equivalent fueled aircraft, even if for somewhat less range, I would seriously consider it. My tolerance for a reduced EV envelope will stretch a bit, and the other guy beside me might have less or maybe more tolerance. Either way, a drastic drop in operating costs would help many pilots get over their reluctance. If somebody could just get over the gap.

I think the Skymaster hybrid conversion is a good step in the right direction. Uses a tried-and-true aircraft as a development platform. They can learn what they need to learn about the practical matters of operating an EV aircraft for a few years, doing it in an airframe with no surprises.

www.sparweb.ca

SW... RE power at wing tips...

The asymmetry with main propulsion [props, driven by EE-motors or fuel-engines] at the wing-tips would be ridiculous… every multi-engine pilot would understand this massive asymmetry... small power differences adding large yaw-torque effects... that would be made much worse with propulsor failure... and a prop that also failed to 'feather'.

HOWEVER... IF the main propulsion [props] delivering ~90% [45% X2 or 22.5% X4] thrust was located inboard at more-conventional thrust locations [pusher~]… with ~10% [5% X2] props at the wing-tips for affecting the wing-tip vortices... that might be a useful/beneficial division of thrust.

NOTE.
I was an O-2A/B engineer for ~3-years and became familiar with the entire bird... that configuration has lots of aero inefficiencies... but is 'sweet' for pilots to fly safely... especially the O-2TT turbine demonstrator with gross excess power.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

Quote (WKTalyor)

... turbine demonstrator with gross excess power.

As a former mentor of mine often said "with engine power, lots is good, more is better, and too much is just enough!"
He built and flew a Pitts Special.


Today, nobody is proposing or even imagining an electric Pitts. Which is a shame - it's almost the right target. A Pitts isn't meant for long journeys. It's entire purpose is to go up, show off, pull off a close call, and then land to change your pants. An oversized electric powerplant and an undersized battery pack would do just fine for that purpose.

www.sparweb.ca

It's the right amount of power when one can do a snap roll, hammerhead stall, another snap roll, and then nail the landing, and the guy at the gas pump admires the way you handle a tail dragger while still on the apron.

Hi Folks,

I did study for one of customers for the diesel proppulsion than i can share some conclusions. Well known turbine engine was used as benchmark :D
- propulsion system weight - twin turbo diesel with comparable power level will be roughly 200-250% heavier than turbine
- take off fuel consumptiom - diesel is wining with 30% margin
- cruise fuel consumption - here is real gain - almost 50-60% for the diesel - but this is based on catalog data, with assuming bigger needs for cooling system and drag related to it's general size we still have nice 30-45% advantege over turbine
- ownership cost - diesels in certification process looks very promising here - most of them is requesting no scheduled maintenance intervals (yeah - guys in marketing departments believe in this - but always will be at least some on life limited parts) and on condition maintenance philospophy
Some words about pusher configuration - i'm digging it out of memory - NACA's data related to US pusher fighter configuration projects (Ascander, Black Bullet projects) have indicated general efficiency gain for pusher in range of 4% - well, problem was that test flights of the mentioned fighters never confirmed such claims - what was confirmed - problematic installation of the engine (large scoops on Celera - 8/10 airplane designs with such powerplant location have ended with difficult to solve issues with powerplant cooling), problems with effectiveness of horizontal and vertical stabilisers and it's control surfaces . Word about Piaggio - from personal experience - is freaking noisy compared to similar airplanes with tractor propellers :D. One more comment - diesel engine availability - by search i did 500HP aircraft diesel available on market is as many as 1 (one) - in development stage. Most of us are perfectly comfortable with situation when we are working on airplane in engine in development stage :D - it never failed isn't it?

The engine (RED A03) does have a TCDS, so a reasonably final design
https://www.easa.europa.eu/sites/default/files/dfu...

when you say "30% margin", I read that as 2/3rds, so a 50% improvement in fuel consumption … much less than the claimed 800% !? (but since when did a new design's early claims prove "optimistic" ?

with the limited supply of aero diesel engines, albeit certified already, I wonder what the price/volumes are like (compared with conventional engines).

"no maintenance" … yeah, right !

another day in paradise, or is paradise one day closer ?

Quote:

Today, nobody is proposing or even imagining an electric Pitts

A slight correction is deserved. Extra tried it. The modified 330 managed a >1,000 FPM climb.

Of course... a Pitts or a Skybolt will climb > 2,000 FPM. Much more...

www.sparweb.ca

jaceb,

I have just been reading up on the Ju 86. During the 1930s, the German experimented with diesel engines for aircraft. Many Ju 86s were powered by Junkers Jumo 205s, which were two‑stroke diesels.

I am not an engine guy. I assume that the two‑stroke cycle made the engines smaller and lighter? The concept did not catch on.

--
JHG

drawoh…

Diesel fuel has always been far more plentiful that refined aviation gasoline... it time of war FUEL AVAILABILITY makes a huge difference.

During the Vietnam war... the following fuels had to me supplied 'in-country'...

MO-gas [auto gasoline]... for small vehicles [Jeeps, Mules, cars, PU trucks, light generators, etc

Diesel... APCs, Tanks... etc... and Heavy trucks, heavy-duty generators, etc,

Bunker Oil.. for heavy warships

80--87 and/or 90-97 octane Avgas for small piston engine Acft [O-1, O-2, etc]

100-130 octane avgas for A-1, A-26, S-2, etc... heavy radial engine Acft... and muddy water patrol boats [using aircraft piston engines] etc...

JP-4 USAF and US Army and early USN/USMC

JP-5 for USN/USMC carrier-based

Jet-A for commercial aircraft

At the beginning of GWI and GWII...

Gasoline, Diesel and JP-4/JP-5/Jet-A and bunker-oil had to delivered in country... plus a few others...

In the Middle of GWII...

The USA, USAF, USN/USMC joined forces to supply 'turbine powered Acft... and multi-fuel vehicles [Diesel, JP5/JP-8, etc] and generators in battlefield... OH yeah and bunker fuel is always needed.

NOW at the end of GWII... Jet-A+ turbine fuel [with military additives] is being used in MOST Acft, ground vehicles and generators… all services... simplifying logistics TREMENDOUSLY. I heard that even UAVs must now be capable of using Jet-A+... gasoline powered UAVs are often grounded for lack of gasoline... unless bought at a local gas-station!

A by-product of using Jet-A is a significant improvement for all vehicles, IE: lower overall fuel cost, increased availability and fire/explosion safety [many aspects].

NOTE. I wonder if the Diesel in the Celera 500 is capable of running effectively on Jet-A???

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

Jet-A was good enough to run it in the HWWMV and a required alternate for the engine in aviation ground support vehicles the AF uses now. The energy density of Jet-A is about 10% lower than Diesel. I assume that would translate to range.

drawoh,

you are perfectly correct - diesel engines are nothing new in aviation, Germans not experimented with diesels but they have it in regular use on Ju86, Do18, Do26 - this kind of propulsion system is perfect for airplanes with power needs up to around 500kW, benefits are clearly visible for the long range/endurance airplanes, north of this line weight to power ratio becoming difficult to accept. Also important factor is that EU Commision is pressing for removing Avgas from use - i've already seen couple circulars which clearly indicationg that this process has been started.In relation to what have been mentioned by 3DDave - F-34 has been standarized as a aircraft/land vehicles fuel within NATO structures - all miltary turbines and diesels has been certified for use this one.

i olmost forgot - not only Germans have been successfull with this kind of engines - Soviets Yer-2 and Pe-8 bombers have used M30 and M40 for stroke/V12 supercharged diesels.

Indeed, 2-stroke diesels led 4-strokes in power density until emissions regulations arrested their development... still, they are current in large low speed marine diesel engines, and some remaining non-emission-critical markets such as military.
The Jumo 205 had several salient features... opposed pistons, which economized on the number of cylinders for a given swept volume, at the cost of an extra crankshaft and gearing between the two cranks. Offset indexing of the cranks allowed tweaking of the port timing.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

Safran is working on 2 stroke boxer turbo diesel for aircraft application - mainly for drop in replacements in General Aviation field - it means we are back in point described by Hemi. Now i would like to put controversional questions - just because environmental factors has been called - by general public diesels are noticed inferrior to the gas engines (due to black smoke from exhaust during acceleration)- is it really true? with it's unmatchable fuel efficiency? - am i really more unfriendly for mother nature when my car is burning 1 US gallon /100km compared to "super efficient" hybrid powered SUV burning 3 gallons and my airplane will be burning less than 50% than turbine powered and 30% less than this one with gas engine? And yes - i'm fully backing idea that Diesel cycle engine is low hanging/ low technology risk level means to noticeably increase fuel economy level at least for the light transport/utility airplanes and light helicopters. Of course it is logic alternative untill battery powered electric propulsion will start rulling - but it is easy, all we need is just increase available power density of batteries 10-20 times and make it safe for use - piece of cake isn't it?

Polish proverb of the day:
Nobody can give you as much as i'm able to promise to you... :D

Certainly the more pernicious pollutants, NOx and particulates, are more difficult to bring to regulated levels in diesel engines compared with spark-ignited engines.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

Hemi,
Of course - but is anybody considered fact that burning 50% less fuel we can be 15% more off regulatory levels and we still will be far more environment friendly than "green" gas engine??? not mentioning that key word in your sentence is "difficult" which means it is not impossible. I'm sure that with proper shaping of cylinder cavity, sound design of the fuel injection system and engine control we may hit regulatory requirements without using all problematic compeonents sitting on the exhaust side.

BTW... on the subject of diesel fuel use in [diesel powered] aircraft...

Is there an aviation diesel fuel standard like those for Turbine fuels????

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

an interesting link …
https://generalaviationnews.com/2011/03/17/jet-a-v....
found by google "aviation diesel fuel specification"

from wiki "aviation diesel engines" ...
"Thielert, based in German Lichtenstein, Saxony was the original TC holder of the 1.7 based on the Mercedes A-class turbo diesel, running on diesel and jet A-1 fuel."

RED diesel says "runs on Jet A1".

another day in paradise, or is paradise one day closer ?

rb… RE Your linked article(s)... my head hurts.

So... NO aviation diesel-fuel standard for diesel-engines powering Acft.

This is troubling in that Jet-A 'works' in Diesel engines... but the consequences for use in Aircraft Diesel's are vague.

SO... I now presume that the Celera 500 Diesel engine must be 'purpose-built' to operate indefinitely/reliably solely on Jet-A... without additives... although it would likely 'work well' using Diesel 1 or 2 with controller adjustments??

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

Just to clarify, when you guys say Jet A you mean just Jet A or is Jet A1 included in that for those of us who come from countries that only run Jet A1.

Quote (jaceb)

Of course - but is anybody considered fact that burning 50% less fuel...

Unfortunately, exhaust emissions don't work that way. To go further into this would be better done in its own thread. Not that I'm much inclined. Rather, if you're really interested in reciprocating engine emissions, diesel vs spark-ignited, there is plenty of information to be found online if you do some searching. You can also post your questions here on Eng-tips on the Engine & fuel forum.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

hahahaha - fuel issue has been widely tested by military personel acros the world - findings are:
1) Jet A1 /F34 is better than standard diesel in a term of much cleaner combustion (higher fuela manufacturing standard?), using Aviation grade fuel noticeably extending life of the injectors in diesels
2) Never run french made diesel engine on JetA1 only - reason is lubrication system of the engine accessories used in French made diesels (pumps are fuel lubricated so you need use fuel lubricating add ons for the two stroke engines) - engines with separate oil lubrication of the accessories run reliably on turbine fuel

this is practical knowledge not dressed in regulatory form of course.

HomeBuiltAirplanes.com forum Jet-A VS Diesel [similar-to discussion]...

Jet-A vs. diesel … https://www.homebuiltairplanes.com/forums/threads/...

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

Hello all,

Let me start, from drawoh initial statement. The Celera 500L cannot be compared with the P-51 from the aerodynamics and design point of view, they are worlds apart on that respect.
But nevertheless I want to show that the P-51D Mustang it’s not 440 mph on 1500 BHP!
As all of us know the Mustang had some big innovations in terms of aerodynamics (laminar airfoils, cooling with Meredith Effect, etc.)
NOTE: We have to be careful always how to compare performance data of different aircrafts, because this is always dependent of the model, weight, altitude, engine model, propeller, etc.!

P-51D

I choose version D, because it was the most mass produced one during WWII.
So from the beginning, the P-51D had a NACA five-digit airfoils (NACA 45-100), they here laminar flow airfoils to 55 to 60% of the chord (this data needs to be validated) but this really depends how the wing was in terms of dents, exposed rivets, bugs, dirt, bear in mind the P-51D was a combat aircraft ...
The P-51D it’s a tractor aircraft, this means any flight surface such as the wing, fuselage, vtp and htp are emerged in the propeller prop wash...means all the laminar flow.. it’s gone! The left overs for laminar flow it’s the outer portions of the wing, but and that regions has the gun ports, meaning only laminar flow on the remaining ~55 % of wingspan.

Now some aerodynamic & performance characteristics:

From wikipedia the following aerodynamic data can be derived, CD0=0.0163, drag area=0,355m^2 and a best L/D=14.6, it’s very good for a single engine tractor fighter aircraft, don´t get me wrong!
From Memo Report No. TSCEP5E-1908:



So at 30000 fts the engine it’s not producing anymore 1490 BHP, but 1180 BHP on War Emergency Power to achieve 439 MPH, this shows how efficient the aircraft was.

So some conclusions, the P-51D has a best glide ratio of 14,6 and a engine (Packard V-1650 Merlin) with a SFC of 0.50 lb/hp/h.

In the second part of my analysis I want to proof that the OTTO Celera 500L shows some credible performance data, and it’s nothing coming out of any eVTOL spinoff company’s BS that it’s very common nowadays.

Unfortunately OTTO Aviation don't provide too much data so I have assumed and estimated most part of the parameters based on my experience and bibliographic data. I would like in the near future to perform a more detailed analysis.

So what we know:

Best L/D = ~22 [1]
Range = 4500NM = 8334 km [1]
Engine = RED A03-003 [1]
Engine Power = +550hp (i.a.w source [5] the engine it’s certified to 500 hp Max TO Power 5 minutes, I will use this value for all performance evaluations).
Engine SFC = 0.35 lb/hp/h. not defined at a specific RPM or Power Setting [3]

END OF PART 1

I read about it in the article, they mention that it has a glide ratio of 22 on their website. Doing a back of the envelope calculation and assuming an engine thermal efficiency of 45 percent, combined with a propulsive efficiency of 90 percent, I get a fuel efficiency of about 74 MPG for a one-tonne aircraft. That would translate into the stated figure if the weight is around 4 tonnes, so it doesn't seem impossible.
But still it sounds very good