octave

This looks interesting but quite long, I have only just started watching so no idea of the content

IF you are able to select a large regen figure..

My understanding is that you do not and cannot perform an action to select the amount of regen you get other than by pulling back power all the way and pitching down. In the video, the instructor points out to the person under instruction that you will hardly notice it except the power usage meter will go into negative numbers. One thing I totally agree with you on though is that the amount of charge is not that impressive. We are not talking about huge amounts of power here. As a range extender, it is not all that impressive. The study that I quoted was from a study using a converted Cirrus sr22. They managed 5.4% but they did not see this as a game changer. My prediction would be that either Pipistrel will improve the efficiency or perhaps drop it. I think if I purchased one with the option I would take it if it was no too much more.

It may also be useful in aircraft that require air brakes but that is something I am not so familiar with. I note that the Pipistrel Virus (piston) does come with airbrakes.

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Look I think we are not necessarily saying much that is radically different. Regen will either improve or it will be one of the many ideas tried and rejected but just at the moment it is still in the game and being studied from NASA down to Pipistrel.

It would come down like a brick if you were to try to get the full re gen rate

It may be more accurate to phrase this "if you come down like a brick you will get full regen (not sure what you mean by full regen)"

"Whilst I accept that a company selling a product may exaggerate or lie this has not been my only source of information. A search of the net does turn up academic papers and conference presentations such as "Matthew D. Olson. "A Conceptual Approach to Flight-Training Mission and Cost Analysis of an All-Electric Aircraft Equipped with Regenerative Energy Devices", Georgia Institute of Technology

I can only read the first page but I have ordered the rest (not to have an argument but because I genuinely would like to learn more).

Of course, I do need to carefully read the whole paper when I get it but it dose say

"Incorporating energy recapture devices improves mission performance by increasing overall at the expense of greater cost and complexity, but large uncertainty as to the device cost and performance exists. They were not considered vital for mission accomplishment in the current state of technology and accounted for 5.4% of the total mission energy requirement"

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It will be interesting to read the whole thing. Now, this is neither a ringing endorsement for regen of various types but it also would suggest that it is not a ridiculous idea.

Here is a clip of a circuit in a electro. From the 7 minute mark, you can see base, final and touchdown. During this time mild regen cuts in and out and for much of time is at net 0. The approach does not seem extraordinary.

My position is this. The company probably exaggerates, possibly quoting the figures obtained a skilled pilot in ideal weather. Interestingly in the clip with Paul Bertorelli from Avweb he asks if there is any regen whilst landing and there was none because the gusty conditions called for an approach with some throttle. So I suspect that at this stage its advantages are probably minimal and a lot would depend on the cost to benefit.

I do not believe that it makes this aircraft into a death machine (slight exaggeration of what you are saying). Whilst the notion that an inexperienced pilot might be chasing regen by lowering the nose too much it is also possible that I could look at the fuel flow meter in the Tecnam and decide that if I poke the nose down I will reduce the fuel flow but of course if I reach the ground before the runway I am in trouble

Anway pending any new information I am probably done.

I've fully explained exactly where the logic is of this is and the small savings that are likely to be obtained.

I agree these are likely to be small savings. I believe in their literature they quote 13% "theoretically" of course we know that manufacturers will provide the most advantageous figures they can calculate.

I am happy to accept your calculations of 3% The modern car is a lot more fuel efficient than the car of 30 years ago. These improvements happened in small increments. A car designer would be pleased with a 3% improvement in economy.

I think your other criticism was if I understand you correctly that because of regen the flying technique would be so different that it may endanger a pilot who has trained in this aircraft when they fly a more standard plane. I learnt to fly in a Thruster then transitioned to a Gazelle and now I fly a Tecnam or occasionally a Pioneer 300. When you pull the power on approach all of these aircraft behave differently. A pilot who learns to fly in a slippery aircraft and then transitions to a draggy machine needs to be taught to get that nose down before reducing the power.

In any aircraft, I have flown, landing is about the pitch and power - (sorry not trying to tell you how to suck eggs). I don't really see that there is a world of difference. In any of these aircraft approach speed is king. If in your electro you if you are maintaining your 60 knot approach speed and because of a steepened approach due to drag from regen you find yourself low then you bump up the throttle 10% giving you no regen so less drag and slightly more power. I don't doubt that there are probably some techniques that are different in this aircraft but the differences between a thruster and a rutan varieze are also important. I guess my point is requiring a different technique should not stand in the way of progress.

I started this thread specifically in this forum rather than the other one because I was hoping for a broader discussion on technological progress. We seemed to have gotten bogged down in one aspect. I mean for all I care they could remove the regen function or they could just call it an airbrake. I am more interested in the big picture.

I am not a Pipistrel fanboy but I do like that they seem keen to invest in progress, whether it be the 4 seater electro or the more ambitious 12 seater hydrogen plane. I believe that the future of most areas of aviation will NOT be battery powered but this training aircraft designed for circuit use not cross country is a good thing and a necessary step along the way to further progress.

nomadpete was probably right, I may have generated a broader conversation on the other forum.

That's like when I got into a lift in a car park and each button for each floor was also in braille...a car park?????

My guess would be that almost every application of elevator buttons would be usable by blind or sight impaired folks. Since having braille poses no imposition on sighted people I would imagine that when a lift is installed they just buy one and don't bother to say hey can you leave the braille off.

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Partially sighted people also use braille.

I did a search on this and found this posting on a forum

Reply

Leoninus Fate 1 year ago

Saying us that are blind cant use a mirror? I have only one eye, I can see faces, I can not read words perfectly, thus is why there is braille, for people that are like me, hell I would have loved this when I was 8 I guess cause you can see, this means you never have to touch braille, I know a lot of people that just touch it and go "wow this is how the blind see" But you dont need it, I imagine you touching it and saying " Im too stupid to understand this"

During my time as a musician in the RAAF we used to do educational concerts at schools including on one occasion a school for deaf kids. This might sound stupid but is not. Deafness is not necessarily total and even totally deaf can feel vibrations. We had kids gathered around to feel the vibrations straight from the instrument.

I would imagine a partially sighted kid would get some pleasure from this. I could also imagine explaining to fully sighted child what these dots are and what braille is for. I don't really see a downside.

Regen performance with different propellors

An Optimal Propeller Design for In-Flight Power Recuperation on an Electric Aircraft

Pipistrel reduces by 6% the energy consumption of an electrical aircraft by optimizing its propeller with FINE™/Turbo

Full paper at An Error Occurred Setting Your User Cookie

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I would imagine these figures were obtained under ideal conditions with a test pilot and therefore may not be realised in everyday flying.

But it won't apply to other" More normal" aircraft. I'm not knocking this plane . Just quantifying the supposed efficiency gain. If you fly other types (as you are permitted to do) you had better be prepared for a significant difference in how its performance varies. Some people do this instinctively and others transition painfully..Thinking you are IN another plane is not helpful. It's more than where the blinker switch is located, stuff. If your engine fails (regardless of how noisy it is/was you must be trained to act appropriately to the situation. With electric there should be a large improvement in reliability as the INFERNAL COMBUSTION reciprocating engine is notorious for failing. It also runs out of fuel due to no fault of it's own. An Electric power unit will also run out of fuel. Planes should be operated on an energy considered basis. Height or speed interchange to a certain extent. High and fast and you must get rid of energy. Low and slow and you are in the Poo as you need energy fast.. Controlling speed with pitch is not an option then. Nev

Nev, what are the claimed figures? Within the stuff I posted they do quantify the expected return, I am just wondering if you have read the claims and dispute them, and if they are incorrect what do you calculate the actual return to be? I understand that plane manufacturers tend to give optimistic specs but I would be surprised if it was totally false. I can only go the published figures and various flight test videos. The manual which I have downloaded points out that the approach is slightly stepper than without regen but not dramatic. In terms of the transition from another plane, well, of course, it would be foolish to just a jump in a different aircraft. I fly a Tecnam and sometimes a pioneer 300 if I haven't flown the 300 for a while I get a check flight. This aircraft is specifically a trainer for use in the circuit., it is designed to be cheap to run and quiet enough to not annoy the neighbours. The circuit pattern does not look radically different and I imagine it would not take long for a piston engine pilot to transition, Here is a training vid of a typical circuit. It doesn't seem to vary wildly from a piston aircraft.

Nev, it doesn't bother me that you are sceptical and I am interested in what you have to say. It makes for a better discussion when the original material and facts and figures are sited and critiqued. The quoted figures may be incorrect but I would expect the flying schools operating these aircraft would have real-world experience.

On the Avweb vid there does not seem to be any special procedure in fact on some of the vids the passenger asks if they are using regen I cant see anything in the Avweb vid that looks to be radically different am I missing something? I think to generate a modest amount of power does not require diving towards the ground.

For a description a circuits

Pipistrel Alpha Electro: The trainer of the future? - AOPA

Several other articles do quantify the amount of regen. I can only assume that it does provide some benefit without reducing performance or safety. Would be interesting to talk to the flying school in Perth to see what their real experience .

Nev they do qote some figures. I have no idea how accurate they are. I can probably post a link to a vid with an interview with the test pilot and designer. Are you saying that regen is not useful in anyway? These aircraft are being used in flying schools in Europe and a flying school in Perth. Time will tell if they are successful or not.

You can't get something for nothing. from an electric motor-generator. If the plane is climbing it's providing extra power to do that. If it's in level fight cruising the thrust has to be a % of the weight dependent on the planes L/D figure. On descent the engine can spin freely or if you use regenerative power, the EXTRA drag will make the descent steeper.. In a clean plane some saving may happen doing circuits if you use engine braking instead of flaps to get you down but the % of extra time in the air will never be a game changer. In say, a 7 min circuit the time getting some electricity back, At a SMALL rate would be lucky to exceed a minute and your time to circuit height at full power is full take off run plus time to downwind turn and about 60% power on downwind. so the input likely is Small bikkies in the big scheme of things. IT probably cost little or nothing to have it, but if someone is claiming BIG advantages, work it out for your self.. Nev

I don't think they are making extraordinary claims about how much charging is produced just a case of squeezing out every ounce of efficiency.

It is always important to consider where medals are from and what they are for and indeed whether or not they are actually medals. I bought this bottle along with some other better bottles whilst in New Zealand. I was so amused by the endorsements on this bottle so I bought it as more of a talking point. Just for the record the endorsement of readers digest is not necessarily a good thing.

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This aircraft has a new design of prop which is optimised for thrust and regen

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Did the dog lick it up, or just take one sniff and move on?

OK, true story. I have just returned from picking up some weekend provisions. Usually, I will buy 1 bottle to drink over Saturday and Sunday. Some weekends like this one I will buy a good bottle and a cheaper bottle so that I may have a couple of extra glasses on Friday. Whilst bringing in the groceries one of the bottles tore through the paper bag and exploded on the driveway. I have yet tried to ascertain whether it was the cheap or expensive bottle yet. I think I need a drink. What is the consensus, too early?

Octave, apologies for thread drift. Back to science.

No problem, thread drifts can be fascinating

I've been part of the wine industry and am a nationally qualified viticulturist (Grape grower) and an enthusiastic good wine consumer

Why was I not informed of this sooner?

If you don't drink the whole bottle

Problem with an older bottle is that once you do find the corkscrew the cork often disintegrates and inevitably you end up pushing the reaming section of cork into the bottle - worth the effort though.

Octave, if the wine cannot breathe due to screw cap instead of cork, you probably need to give it mouth - to - mouth .....david

Understood and will comply

I was just pouring myself a glass of chilled rose' and the question popped up in my mind - Are screw-tops better for wine bottles than corks?

Yep, screw caps are superior for younger wines, the ones that the likes of us can afford. Cork is said by some to be better for wines that need to age. I think the idea is that a little oxygen entering through the cork is supposed to be beneficial in the ageing process.

I don't really believe (and have never believed) that life has a grand purpose. In the absence of a grand purpose for me at least is the purpose I give it. I feel a great sense of privilege for just existing in the first place. I have the privilege of being born at a time in history when my odds of surviving into old age are better than in days gone by. I can understand that in a time or place when/where 5 of your 8 children would probably die at a young age and if you were lucky you might reach the grand age of 50, the idea of a grand plan or benevolent overseer was an attractive idea.

I have always enjoyed walking around old cemeteries. I often see ornate and large structures, many of the more recent ones are obviously well visited and looked after but other older ones are often in disrepair. Obviously, anyone who knew or cared for that person is also gone. For some reason I actually find this to be quite comforting. I do not want to be remembered by people I have never met or interacted with.

Now for the life advice. I say be grateful for all the good things in life, realize that for us middle-class folks in the 1st world the problems we whinge about are minuscule compared to 3rd world or in days gone by. Create meaning and a purpose but realize that this is your personal thing and may be of interest to others but probably not. Lastly don't be a dick i.e. be kind.

Sorry to be pedantic Octave, but I think you probably meant to post this in the other forum.No offence intended.

Actually no, I did intend to post it here as a technology post. I seldom contribute to the other place.

Cryogenic energy storage (CES)

Cryogenic Energy Storage