Cobalt wrote:
BTW – the electric motor will weigh a lot less than the 144kg you allow, more around 20-50, but the battery a lot more than 166kg. 166kg is just the cells required for the capacity stated, and does not include cabling and mounting.
I took these figures from you I believe 
But it does not matter, we all know that any plane whose paylod is given as x in the advertisment will have so much very rarely. Looking at the 150 kgs an average C150 can carry (is that where the designator comes from? 
) there is margin.
Cobalt wrote:
. The 1.5 hours to empty battery are at 33kW, and if you remove a bit for climb you have 30kw / 40 bhp left. What percentage that is of anything is not relevant, but cruising 850kg at 40 bhp?
Um. yea. I now see that: 50 kwh is the capacity. Max power draws 90 kwh and 65% draws 65 kwh. So 90 min is indeed at 33 kwh, which is closer to 40% power.
With 65% you’d end up empty after 50 minutes and with 30 mins reserve….
So rather a “circuit bicycle” (zu Schweizerdeutsch: Platzrundenvelo) indeed. And I’d say 40 minutes to empty there if you calculate that it will per 6 minute circuit run 2 on 90kwh and the rest maybe at 50kwh. So one circuit will drain about 6.5 kwh… That makes about 7 circuits to empty. And maybe that is why they have flaps extended? At 40% power it might well end up falling out of the sky without them.
Mooney_Driver wrote:
Actually I think that it will have to be if it is certified under CS23 so that is one more bit they have to solve.
It does not appear that it has to be. This is the relevant part of CS23:
CS 23.2150 Stall characteristics, stall warning, and spins
(a) The aeroplane must have controllable stall characteristics in straight flight, turning flight, and accelerated turning flight with a clear and distinctive stall warning that provides sufficient margin to prevent inadvertent stalling. A stall warning that is mutable for aerobatic flight phases is acceptable.
(b) Single-engine aeroplanes, not certified for aerobatics, must not have a tendency to hazardously depart from controlled flight inadvertently.
(c) Level-1 and -2 multi-engine aeroplanes, not certified for aerobatics, must not have a tendency to hazardously depart controlled flight inadvertently from thrust asymmetry after a critical loss of thrust.
(d) Aeroplanes certified for aerobatics that include spins must have controllable stall characteristics and the ability to recover within one and one-half additional turns after initiation of the first control action from any point in a spin, not exceeding six turns or any greater number of turns for which certification is requested, while remaining within the operating limitations of the aeroplane.
(e) Aeroplanes intended for aerobatics have the ability to recover from any approved manoeuvre, without exceeding limitations or exhibiting unsafe characteristics
The AMCs could provide addition information but they refer to standards that you have to pay for.
Thanks for the correction on the weight!
Since they have an extra 250kg to play with, the entire engine + battery assembly could weigh around 350-400kg, instead of the 140kg I calculated. For a 50kWh battery that now looks plausible, even if you take into account a slighly beefier structure to carry the increased MTOW. BTW – the electric motor will weigh a lot less than the 144kg you allow, more around 20-50, but the battery a lot more than 166kg. 166kg is just the cells required for the capacity stated, and does not include cabling and mounting.
But overall, you are clearly correct – the claimed battery capacity and power are completely plausible.
Your range estimate is, however, a bit optimistic. The 1.5 hours to empty battery are at 33kW, and if you remove a bit for climb you have 30kw / 40 bhp left. What percentage that is of anything is not relevant, but cruising 850kg at 40 bhp? Not going fast… it is not clear what speed they will get, but if their 1.5 hours is a sensible endurance, it will be somewhere between minimum sink and max range speeds, so say 1.2 – 1.35 stall speed. 60-70kt.
So I correct myself to
“An aircraft that flies 100 miles in 1 hour and 15 minutes which has not been certified yet”
mh wrote:
Do you add the Overhaul Cost of your O360 to the fuel cost, too? I think Battery service is, as well as engine service, part of maintennace costs, not wnergy/fuel costs.
Not to the fuel cost but to the operating cost that is price per hour. So that is what the bottom line has to be, how much does it cost to operate per hour. You are right to point out that this is part of another cost factor. So it has to be compared to the pure fuel cost of a comparable engine, which would be a O200 or Rotax imho. The O200 burns about 20 liters per hour, which today is very roughly 75 Euros fuel cost only, so the 7 Euros would be rather cheap indeed. However, avgas planes can fly much longer, so the additional cost of more landing fees e.t.c. will have to be taken into account.
E.g: This plane can not cross Switzerland east-west in one leg due to range. (It can cross Liechtenstein or Luxembourg however ). A C150 can. So it would have to land someplace and stay on the ground for 2 hours (90 mins charge, 30 mins overhead) until it can go on and pay the landingfee in, say Bern or Grenchen, which adds about 40 Euros to the price. So trip cost with consumables only from say, Altenrhein to La Cote (Nobody goes to Geneva these days) would be about 120 Euros for the Cessna (1:50 flight time, 40 liters Avgas = 100 Euros plus landing fee). The H55 would have to land at Grenchen or somewhere else half way to recharge and be airborne for about the same time due to the additional approach and landing. So 14 Euros fuel cost, 35 Euros landing fee at Grenchen and about 20 at La Cote comes up to around 70 Euros… clearly cheaper but time elapsed will be 2 hours longer.
mh wrote:
What makes you think, the B23 won’t be recoverable from a spin?
Actually I think that it will have to be if it is certified under CS23 so that is one more bit they have to solve. The discussion is that the UL/VLA Version if the similar cell is not, so that is a problem even now. IMHO no airplane, be it whatever cathegory, should be certified without being able to be recovered from a spin or at the very least if such an airplane exists it has to have a BRS system.
Peter wrote:
How can a plane be “certified” if it cannot recover from a spin?
AFAIU it is sufficient if it can recover from an incipient spin, not a fully developed spin. IIRC, the PA28 is in that category.
At Aero i noted that the vertical stabilizer of the B23 and the UL version were different. B23 a bit more upright and placed a bit more forward. Milan Bristela told me that makes the B23 spin recoverable. We did not discuss whether the UL is impossible to recover from a spin. It does have a parachute though and has very noble handling characteristics. Does not drop a wing in a full stall, if the ball is centred.
The claim of energy cost of 7 Euros per hour will have to be verified. In terms of pure electric power it might work, I have my doubts however if this includes necessary battery changes after the original pack can no longer sustain full power. I don’t know enough about this battery to know how long you can use it until it needs replacement but if it does, it is likely to be costly.
Do you add the Overhaul Cost of your O360 to the fuel cost, too? I think Battery service is, as well as engine service, part of maintennace costs, not wnergy/fuel costs.
I somehow doubt that a plane can be certified CS23 with irrecoverable spin characteristic and no BRS. Also, in the video shown, the plane seems to be flying with flaps extended to some extent.
What makes you think, the B23 won’t be recoverable from a spin?
The H55 website sais MTOW is 850 kg. You even quote that. Therefore the weight calcs would look something like:
MTOW 850 kg
Payload 200 kg
Operating Weight : 650 kg, as there is no ZFW for obvious reason, the plane weighs the same fully “fuelled” or not.
So if you calculate on that:
Basic airframe without engine based on the Classic: 260 kg
Electric motor : 144 kg
Battery Pack : 166 kg
gives a total of 570 kg. So there is still a difference to the 650 kg operating weight the numbers suggest, which could be reinforcements (higher MTOW) and possibly a BRS to achieve the 200 kg payload.
I think the 90 mins are to a flat battery. The website states:
The airplane has an endurance of 1.5 hours, providing 45-60 minutes of mission flight with enough reserves, a typical training program for flight schools.
At 65% power the cruise speed should be in the region of 100 to 110 kts. So in practice, that means you can fly between 100-110 NM and are left with 45 mins of reserve. With a 30 mins reserve, you’d end up with 125 NM still air range.
Clearly, this is not a lot but it can do the job for flight schools in basic training. Basically it would mean you can do either about 60 -70 mins of circuit training or enroute flights of about 100-120 NM range, which should roughly do the trick for the PPL program when planned properly. I just had a look at my “nav flights” and apart from a 90 minute charge break at the far out destination it would not change much of today.
For example: My Nav Flight was Altenrhein, Wangen Lachen, Grenchen (90 NM altogether) and back routed around the ZRH CTR. 73 NM to Grenchen and 100 NM back. Nowadays, both Altenrhein and Grenchen have bases for the same training organisation so charging up in Grenchen would not be a problem.
The claim of energy cost of 7 Euros per hour will have to be verified. In terms of pure electric power it might work, I have my doubts however if this includes necessary battery changes after the original pack can no longer sustain full power. I don’t know enough about this battery to know how long you can use it until it needs replacement but if it does, it is likely to be costly.
H55 also states that this is a product they intend to use as a proof of concept that electric flight in CS23 is not only possible but a viable solution for flight schools.
I somehow doubt that a plane can be certified CS23 with irrecoverable spin characteristic and no BRS. Also, in the video shown, the plane seems to be flying with flaps extended to some extent.
They are a long way from home I suppose, but coming from where this is coming from and headed by core people from the Solar Impulse project, it may well be one to watch. The first question I’d put to Andre Borschberg would be why the wings are not equipped with solar cells to extend the range. In this kind of range environment of 100 NM or so, even 10 – 20 mins more endurance would mean a lot. Probably that is what they might be thinking along the future.
For basic flight training and given that the spin problems would be solved one way or the other, I suppose flight schools will be interested. Here in Switzerland with organisations like Swiss PSA which is spread all over the country, there definitly would be possibilities to use this concept in basic training. Given their bases, it would even be possible to have airplanes rotate from place to place, e.g. to have a crew fly from one to the other base, change airplanes and continue while the original one is charged and so on. It is far from a ripe concept but it may well be a start.
Let’s keep this on the topic please.
How can a plane be “certified” if it cannot recover from a spin?
Cobalt’s analysis yields a result which is unsurprising. These things just don’t add up. There is no doubt a plane can be made which can fly circuits around an airfield, so it could be used for a bit of PPL training, but what about the rest? Is a flying school going to organise a standard route for the cross country training flights, with chargers positioned at the right places, and fly those routes only when the wx is absolutely assured? PPL training is already a huge hassle for some, with every solo flight cancelled for months if there is say 3km-5km haze. Maybe a number of schools can set it up together.
Sorry to hear about your friend, dublinpilot.
WilliamF wrote:
Certain local Cessna 150 … accidents all jumping to mind where the aircraft design let the pilots down.
What happened with the Cessna 150 which was design related? I thought the 150/172 designs were one of the safest around.
