Primarily for general aviation discussion, but other aviation topics are also welcome.
#1844619
Iceman wrote:As technically interesting as this project may be, some parts of the company’s text trouble me.

the crew were able to safeguard the battery and safely release hydrogen from the onboard tanks, following ZeroAvia safety protocol;
.

If the fuel cells weren’t compromised then why vent the fuel into a post-crash, potentially explosive atmosphere ? That would appear to be a bit like someone saying that there were no holes in an AVGAS fuel tank, but we’ll drain all of the fuel out anyway. It would read much better to me if they’d said that they’d left it to the formal AAIB investigators before disturbing the accident scene and altering crucial accident investigation evidence.

Iceman 8)


Likely because of the unique combustion properties of hydrogen. If there was a hairline failure in the pressure vessels and a leak which did ignite, then the hydrogen flame would be undetectable to the naked eye. This could have been a major hazard to a potential post crash recovery and as there are no consequences to venting to atmosphere, then it would seem the prudent thing to do. I would imagine this is SOP for them, rather a controlled release than an accident later on!

At facilities with hydrogen gas, IR flame detectors are required and straw brooms (burns visible upon contact with a hydrogen flame plume) are used to detect otherwise invisible fires.

Andy
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#1844623
Whilst we’re on alternative fuels, I see that Porsche are investing in the manufacture of synthetic fuels for their flat 4 and flat 6 car engines (similar to ours): https://www.autocar.co.uk/car-news/indu ... fuels-2022

Having looked into this, the plan is to use renewable energy to extract and convert CO2, O2 and H2O into a hydrocarbon. This also burns cleaner than ‘dead dinosaurs and trees’ too. So maybe we won’t have to completely give up the internal combustion engine - but we should move away from AVGAS100LL as soon as possible - all that TEL is nasty!

Image

"At full scale, we expect a reduction in the CO2 impact of around 85%. If you consider well-to-wheel, where we have to transport fuel, we have a global supply chain, everything around that - you have efficiency across the whole process. In a well-to-wheel consideration, it is on the same level as an electric car."
#1844643
gaznav wrote:@Rjk983

I completely agree. However, the Bye Aerospace eFlyer 2 has now got 3 hours flight time plus 30 mins reserves and a 15kts higher cruise speed than the Pipistrel. It also has a Rolls-Royce (late Siemens) electric motor. Plus, how cool does it look too? :thumleft:

It does look cool! But they state themselves that 3 hours is absolute (so no reserve) and the maximum endurance applies for a cruise speed of 73 kts, so not 15 kts higher than the Pipistrel Velis.

I think it's great that there are all sorts of initiatives around "green" flying. Hydrogen, batteries, artificial hydrocarbons, JET fuel made from pine trees,... Not everything will pan out, but perhaps some will. The aviation industry, starting with GA and smaller commuter aircraft, may be entering a change as big as when jets overtook piston aircraft for CAT.
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#1844644
gaznav wrote:@Rjk983

I completely agree. However, the Bye Aerospace eFlyer 2 has now got 3 hours flight time plus 30 mins reserves and a 15kts higher cruise speed than the Pipistrel. It also has a Rolls-Royce (late Siemens) electric motor. Plus, how cool does it look too? :thumleft:

Image

Three production-conforming aircraft will take part in the flight-test campaign, with US Part 23 certification scheduled for mid-2021. The eFlyer 2 is powered by a 120hp (90kW) Rolls-Royce RRP70D electric motor, delivering speeds of over 135kt (250km/h) and an endurance of over 3h.


It does look cool, and the first production fuselage is in manufacture, with hopes of FAA certification down the line. If they manage to keep its purchase price at $0.5m then they should be able to compete with Cessna et al for the ab initio trainer market.

If we harness the collective brain power of the “I bought another leaf” and the “home automation” threads then we can probably come up with a decent LAA type power train...
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#1844647
Iceman wrote:@andytk58, why is venting to atmosphere any less hazardous than ‘having a leak’ when it comes to an accident site ?

Iceman 8)


Solely slightly informed speculation, but I suspect that the gas would disperse rapidly and a flammable atmosphere would only exist transiently next to the aircraft, whereas a slow leak from a fractured tank would potentially maintain the chance of fire/explosion around the aircraft for some considerable time period.

It sounds like all these things were relatively well thought through prior to the accident. I’m sure they will learn from it all and the whole effort will benefit. I don’t have any problem with them making the aircraft safe at the accident site, and I suspect nor will the AAIB as long as they can document what they did and when.
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#1844651
Iceman wrote:@andytk58, why is venting to atmosphere any less hazardous than ‘having a leak’ when it comes to an accident site ?

Iceman 8)


Hydrogen is so light that it dissapates vertically almost instantly so no risk of explosion. Plus I would imagine the vent lines run to the aircraft exterior. What you don't want is any amount of gas mixing in an enclosed, crumpled fuselage with possible sparks.
If I had just subjected a pressure vessel to an unknown impact I'd want them depressurised asap to reduce the chance of further issues.

Andy
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#1844655
@akg1486

Thanks for the extra info. I did have another squint at the eFlyer after your post and it quotes “96kts at economy cruise with a 220nm range with VFR reserves” - which is about 2hrs 20mins with the FAA required 30 mins of reserve. The Pipistrel economy endurance cruise is 75kts and they use 60 mins and a 30 min reserve.

So, I think it’s safe to say that the eFlyer cruises at 21kts faster and with that has 1hr 20mins better flight time. That’s quite a difference. But then there is the price - the eFlyer 2 is $489,000 (£349,000), whereas the Pipistrel Electro is just €130,000 (£113,000) in its most basic form. But if I had the choice, I’d be buying the eFlyer :thumleft:
#1844676
gaznav wrote:@Rjk983

I completely agree. However, the Bye Aerospace eFlyer 2 has now got 3 hours flight time plus 30 mins reserves and a 15kts higher cruise speed than the Pipistrel. It also has a Rolls-Royce (late Siemens) electric motor. Plus, how cool does it look too? :thumleft:

Image

Three production-conforming aircraft will take part in the flight-test campaign, with US Part 23 certification scheduled for mid-2021. The eFlyer 2 is powered by a 120hp (90kW) Rolls-Royce RRP70D electric motor, delivering speeds of over 135kt (250km/h) and an endurance of over 3h.


Looks like an RV to me
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#1844736
gaznav wrote:@akg1486

Thanks for the extra info. I did have another squint at the eFlyer after your post and it quotes “96kts at economy cruise with a 220nm range with VFR reserves” - which is about 2hrs 20mins with the FAA required 30 mins of reserve. The Pipistrel economy endurance cruise is 75kts and they use 60 mins and a 30 min reserve.

So, I think it’s safe to say that the eFlyer cruises at 21kts faster and with that has 1hr 20mins better flight time. That’s quite a difference. But then there is the price - the eFlyer 2 is $489,000 (£349,000), whereas the Pipistrel Electro is just €130,000 (£113,000) in its most basic form. But if I had the choice, I’d be buying the eFlyer :thumleft:

As you may or may not have seen, I started a thread about the Velis in September when our club got delivery of one. The second type rated electric aircraft in the world, actually; the first went to a Pipistrel partner in Switzerland. We don’t own it but we operate it. The last status update was when our school submitted its training plan for the difference training to simple electric aircraft. Our CAA issued the requirements in late February. We still have no news, so the aircraft sits in the hangar: only two instructors have temporary permission to fly based on training at the factory.

I’ll be posting more in that thread as things move along. Search for the keyword ”SE-KWH” (the registration) and you’ll find it.
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#1844776
Thanks @akg1486 - that’s grand. I look forward to reading your updates on the real world figures. Early days for all, but an exciting change. I watched a video about the Electro the other day, and it was great to see how quiet it was. So another advantage is lower noise pollution for circuits where local NIMBYs constantly complain about engine noise.
#1844821
andytk58 wrote:..

Likely because of the unique combustion properties of hydrogen. ..

At facilities with hydrogen gas, IR flame detectors are required and straw brooms ..


One of the best things about these Forums is that on almost any topic tangentially connected to aviation (and sometimes with no connexion at all :) ) there is likely to be at least one Forumite, and often more, with a pertinent expert knowledge and a willingness to share it dispassionately. :thumright:

[Incidentally, in that respect, they sometimes resemble obscurer and underreported Select Committees of the House of Lords. There, non-political cross-bench Peers can often provide expertise, and penetrating scrutiny of Bills and witnesses, in ways in which Commons ones cannot.]
#1844871
kanga wrote:One of the best things about these Forums is that on almost any topic tangentially connected to aviation (and sometimes with no connexion at all :) ) there is likely to be at least one Forumite, and often more, with a pertinent expert knowledge and a willingness to share it dispassionately. :thumright:

I find that the same applies in my flying club. While we do have a lot of project managers and IT consultants, we also have professionals in many fields who know a lot. Some have expertise in several fields: one pilot in our club is a professor in medicine and a former 80s rock star (on the national level, so you won't know him). In fact, the boxing world heavyweight champion Ingemar Johansson took flying lessons with us. That was way before my time, of course. Before I was born, even. :D

I think that most GA pilots are people who are eager to learn new things; that was one major motivation for me to become a pilot. And people who are eager to learn are also often eager to pass on what they know.
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