Search found 3790 matches

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by kalvado
Sat Dec 03, 2022 11:56 pm
Forum: Technical/Operations
Topic: Fan with electric core - possible?
Replies: 22
Views: 661

Re: Fan with electric core - possible?

We haven’t had any modern planes spontaneously start fire in flight using fossil fuel. TWA800. And I heard a rumor B-52 exploded at Sawer had a similar issue. TW 800 was a wiring issue. Yes, and several other planes have had ground fires, usually lightning strikes or static discharge due to imprope...

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by kalvado
Sat Dec 03, 2022 11:42 pm
Forum: Technical/Operations
Topic: Fan with electric core - possible?
Replies: 22
Views: 661

Re: Fan with electric core - possible?

eeightning wrote:
Engine weighs 1/2. Fuel weighs 1/5. That leaves a lot of room for fuel cells and tank insulation.

I believe that pretty much sums the state of the art in hydrogen propulsion over past few decades.

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by kalvado
Sat Dec 03, 2022 11:36 pm
Forum: Technical/Operations
Topic: Fan with electric core - possible?
Replies: 22
Views: 661

Re: Fan with electric core - possible?

GalaxyFlyer wrote:
We haven’t had any modern planes spontaneously start fire in flight using fossil fuel.


TWA800. And I heard a rumor B-52 exploded at Sawer had a similar issue.

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by kalvado
Sat Dec 03, 2022 10:20 pm
Forum: Technical/Operations
Topic: Fan with electric core - possible?
Replies: 22
Views: 661

Re: Fan with electric core - possible?

What sort of compact light electric motors are there that could replace the gas turbine core on a commercial airliner? We are talking motors in the 2,000 kw to 50,000 kw range. Is there anything like that at TRL 8? What is the TRL of fuel cells capable of supplying that size motor? I believe fuel c...

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by kalvado
Sat Dec 03, 2022 9:18 pm
Forum: Technical/Operations
Topic: Fan with electric core - possible?
Replies: 22
Views: 661

Re: Fan with electric core - possible?

Hydrogen as fuel runs into volumetric issues. Presumably we're discussing this in the context of environmental friendliness. Batteries obviously have energy density/volume issues. The Mass issue is even worse. As we know, as such an aircraft won't "lose weight" throughout a flight. As for...

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by kalvado
Sat Dec 03, 2022 11:16 am
Forum: Technical/Operations
Topic: Fan with electric core - possible?
Replies: 22
Views: 661

Re: Fan with electric core - possible?

So basically there are no hard, technical problems there with such a concept, it's more an issue of fuel volume/range limitations as such, and fuel availability. Thanks for your input. Cheers, Adam There is a concept of "technology readiness level", TRL. It's a 1-10 scale, where 1 means b...

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by kalvado
Fri Dec 02, 2022 8:42 pm
Forum: Technical/Operations
Topic: Fan with electric core - possible?
Replies: 22
Views: 661

Re: Fan with electric core - possible?

If you can magically store H2 with total energy density per weight and per volume better than that of kerosene, you may start talking drop-in replacements. I'm well aware of lower energy density of H2 liq. https://www.energy.gov/sites/default/files/styles/full_article_width/public/fcto_storage_fuel...

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by kalvado
Fri Dec 02, 2022 8:20 pm
Forum: Technical/Operations
Topic: Fan with electric core - possible?
Replies: 22
Views: 661

Re: Fan with electric core - possible?

Question is where your design target point is. As far as I understand, fan becomes beneficial at higher speeds, while prop may be more efficient at lower speeds - and for shorter range that is less important. So you loop back at the range of the airplane, which would bring you to fuel storage requir...

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by kalvado
Thu Dec 01, 2022 8:36 pm
Forum: Technical/Operations
Topic: Hawker siddeley trident wing
Replies: 32
Views: 5389

Re: Hawker siddeley trident wing

Dear all, Thank you very much for these insights. I definitely learned something. Now I'd like to ask, how do they design the "automatic pitch down in a developing stall" in a straight wing, e.g. for the Q400 or ATR? A higher pitch angle at the wing root wouldn't change the center of lift...

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by kalvado
Tue Nov 29, 2022 9:57 pm
Forum: Technical/Operations
Topic: Hawker siddeley trident wing
Replies: 32
Views: 5389

Re: Hawker siddeley trident wing

Here is the best I have: This is a very interesting drawing. Take a look at the obvious wing twist from the root to the tip. The angle of attack is significantly higher at the root. Would this design feature induce a stall behavior where the root stalls first, moving the center of lift backwards, t...

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by kalvado
Tue Nov 29, 2022 9:24 pm
Forum: Technical/Operations
Topic: Hawker siddeley trident wing
Replies: 32
Views: 5389

Re: Hawker siddeley trident wing

Here is the best I have: This is a very interesting drawing. Take a look at the obvious wing twist from the root to the tip. The angle of attack is significantly higher at the root. Would this design feature induce a stall behavior where the root stalls first, moving the center of lift backwards, t...

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by kalvado
Sat Nov 26, 2022 3:05 pm
Forum: Technical/Operations
Topic: Question about brake and rudder pedals.
Replies: 20
Views: 1820

Re: Question about brake and rudder pedals.

The braking pivot point is towards the bottom of the pedals, not the middle. The whole thing is quite easy to get used to. Within half an hour or so in your first light aircraft it becomes second nature to steer and brake with your feet. Just wondering if you ever get confused switching between coc...

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by kalvado
Sun Nov 20, 2022 3:30 pm
Forum: Technical/Operations
Topic: ETOPS certification of passenger-to-freighter converted aircraft
Replies: 20
Views: 1978

Re: ETOPS certification of passenger-to-freighter converted aircraft

ETOPS is a costly status to maintain if you don't really need it. There is a lot of training and record keeping. Many of the aircraft's components require specific maintenance, which is an added cost. These components are in just about every system that would cause a plane to divert. Yes that inclu...

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by kalvado
Sat Nov 19, 2022 2:26 pm
Forum: Technical/Operations
Topic: The manufacturing of the current 767
Replies: 12
Views: 2088

Re: The manufacturing of the current 767

I've always wondered on the 757 and 767 there were two types of throttle lever design. A slimmer grey set, tended to be on earlier builds and a bulkier burgundy set on later builds. Was this dependent on engine type? I know the the RR on the 757 and earlier builds the engines were mechanically link...

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by kalvado
Fri Nov 18, 2022 2:04 am
Forum: Technical/Operations
Topic: Non-Operational Reasons That Seats Might Be Held Back From Sale (United Express)
Replies: 20
Views: 2458

Re: Non-Operational Reasons That Seats Might Be Held Back From Sale (United Express)

A CRJ-200 has an average empty weight of 31300 lbs - each aircraft is different Max Takeoff Weight is 53,000lbs, max landing weight is 44,000lbs, max zero fuel weight is 47,000lbs So we are going on a flight from RIW to DEN a distance of 274nm along a routing of KRIW TOFUU.FLATI3 KDEN enroute fuel ...

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by kalvado
Fri Nov 18, 2022 1:23 am
Forum: Technical/Operations
Topic: ETOPS certification of passenger-to-freighter converted aircraft
Replies: 20
Views: 1978

Re: ETOPS certification of passenger-to-freighter converted aircraft

Many variables in play here. Is ETOPS required for freight? I don't think it is, but I might be all wet. It might be a local requirement for certain freighters. The A/C that kept ETOPS during conversion may be subject to leasing terms, where the residual value of the A/C is less without the ETOPS c...

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by kalvado
Tue Nov 01, 2022 7:05 pm
Forum: Technical/Operations
Topic: Turboprops vs Turbofans.... and Propfans!
Replies: 24
Views: 2890

Re: Turboprops vs Turbofans.... and Propfans!

As far as I remember, service ceiling is a significant factor. Dash-8 and ATR are limited below FL300, while RJ can go over FL400. Are you aware it's not a powerplant limit, but a general choice of aerodynamic efficiency vs payload vs range? There are turboprops able to go way above F300. Dash8 and...

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by kalvado
Tue Nov 01, 2022 12:46 pm
Forum: Technical/Operations
Topic: Turboprops vs Turbofans.... and Propfans!
Replies: 24
Views: 2890

Re: Turboprops vs Turbofans.... and Propfans!

what about "above the weather" part - can you comment? It all depends on where you're flying. In Alaska or Northern Canada the low 20s is plenty to get you above 99% of the bad weather even in the summer; I can remember only once in several years being faced with a line of thunderstorms (...

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by kalvado
Tue Nov 01, 2022 10:13 am
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

Pilots are conservative creatures and in the decades gone by where we did on occasion use charts, there was excessive rounding up and intercalation. As much as we would like to have very precise data, my impression is that even using an app or other electronically calculated data, there is still co...

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by kalvado
Mon Oct 31, 2022 5:27 pm
Forum: Technical/Operations
Topic: Turboprops vs Turbofans.... and Propfans!
Replies: 24
Views: 2890

Re: Turboprops vs Turbofans.... and Propfans!

Very empty RJ above F400, certainly no CRJ. Very true, spoken from experience. Mid-high 20s was our typical domain; even 310 was a struggle. Did 370 once but that was on an empty repo flight so it really doesn't count. WHat is the usual cruise of a turboprop? Service ceiling is an official number f...

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by kalvado
Mon Oct 31, 2022 12:39 pm
Forum: Technical/Operations
Topic: 787-10 floor vibration
Replies: 26
Views: 5358

Re: 787-10 floor vibration

Took a BA 787-10 flight from SEA to LHR some months back and was in 13A which is towards the front of the wing. As we got into cruise I noticed a really uncomfortable vibration cycle, similar to what I often feel on ships/ferries as best I can describe it. It was over about 8s or so as I remember, ...

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by kalvado
Mon Oct 31, 2022 10:59 am
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

I would think manufacturer charts are for best case situation in terms of runway performance. Actually, Boeing chart specifically shows what flaps settings are being used at which conditions, so they must have some idea about flaps effect. If you choose to trade in longer roll for less engine wear ...

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by kalvado
Mon Oct 31, 2022 10:51 am
Forum: Technical/Operations
Topic: Turboprops vs Turbofans.... and Propfans!
Replies: 24
Views: 2890

Re: Turboprops vs Turbofans.... and Propfans!

GalaxyFlyer wrote:
Very empty RJ above F400, certainly no CRJ.

WHat is the usual cruise of a turboprop? Service ceiling is an official number from the datasheet - easy to find, easy to verify...

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by kalvado
Sun Oct 30, 2022 10:38 pm
Forum: Technical/Operations
Topic: Turboprops vs Turbofans.... and Propfans!
Replies: 24
Views: 2890

Re: Turboprops vs Turbofans.... and Propfans!

As far as I remember, service ceiling is a significant factor. Dash-8 and ATR are limited below FL300, while RJ can go over FL400. As a result, there is a non-insignificant pool of cases when RJ can go above the weather, but turboprop has to go around the weather, burning more gas and subject payloa...

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by kalvado
Sun Oct 30, 2022 2:08 pm
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

Probably minimal possible runway meaning max thrust. Although one thing to keep in mind - MTOW bumps without thrust bumps mean more runway, and at the tail end of the curve even small weight increase means a lot more concrete. A bit of thrust increase may shorten the roll significantly. Early versi...

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by kalvado
Thu Oct 27, 2022 7:53 pm
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

I doubt you'll get a direct answer. Here is an attempt, though. Below is comparison of performance data from airport planning manuals. A332 with PW4000 vs 787-8 with "high thrust rating". x-axis is adjusted so that scales match. "High thrust engines" (shown) version has a bit sh...

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by kalvado
Sun Oct 23, 2022 11:02 am
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

I always wondered, is there any difference in the takeoff performance of both aircraft in most conditions. If there's a noticeable difference, who's the better performer? I have heard people say the 787 is a runway hog, but I remain unconvinced by that as there's not much evidence to such claims. I...

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by kalvado
Sat Oct 22, 2022 11:11 pm
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

Design is based requirements, no reason to go beyond the regulatory requirements. Akin’s Laws of Engineering Of course, and if requirements are set by bureaucracy, then results are primarily bureaucratic. However, I suspect quieter new generation is partially due to going beyond minimum, although f...

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by kalvado
Fri Oct 21, 2022 11:43 pm
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

It’s not “shut up”; it’s that there’s a process to evaluate aircraft noise signatures, present them in a form usable by anyone that needs to test for Stage II or III compliance and for compliance with airport noise rules, whichever is more restrictive. See KSNA or YSSY night time curfews. I chose Y...

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by kalvado
Fri Oct 21, 2022 9:40 pm
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

And, “good enough” is just that. No one needs to know frequency, noise source down to a overfill drain, except perhaps engineers tasked with identifying sources and fixes. The public, Airport Operators and crews don’t need it. The standard is for basic comparisons. No operation in actual aviation w...

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by kalvado
Fri Oct 21, 2022 8:14 pm
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

Who are going to believe, scientific engineering data or your lying ears? I don't see any scientific data in the TCDSN. It is a totally bureaucratic document. I see tables of measured noise levels, not a bit bureaucracy. Specifically, flyover noise level at different mass. https://www.easa.europa.e...

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by kalvado
Fri Oct 21, 2022 4:36 pm
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

GalaxyFlyer wrote:
Who are going to believe, scientific engineering data or your lying ears?

I don't see any scientific data in the TCDSN. It is a totally bureaucratic document.

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by kalvado
Fri Oct 21, 2022 11:56 am
Forum: Technical/Operations
Topic: 787 vs A330 Runway Performance/Requirements
Replies: 55
Views: 6864

Re: 787 vs A330 Runway Performance/Requirements

Guys, I get it. I'm just saying that it's a little strange that they are always lower and significantly louder departing after 10 pm in an area that has one of the highest noise complaint rates in the country. I understand weights, derated takeoffs, climb profile efficiencies, fuel cost, etc. One o...

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by kalvado
Tue Oct 18, 2022 2:09 pm
Forum: Technical/Operations
Topic: Turboprop Airliners and Blade Failures
Replies: 26
Views: 3547

Re: Turboprop Airliners and Blade Failures

Regulation mandates modern Turbofan engines to have a containment duct which encloses the Fan cowling area of the engine. Shouldn't the ice shield also designed as a protection device in case of prop blade liberation.? That pretty much means converting prop to the turbofan for a very different set ...

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by kalvado
Mon Oct 17, 2022 6:56 pm
Forum: Technical/Operations
Topic: concorde with more than 100 passenger?
Replies: 27
Views: 4438

Re: concorde with more than 100 passenger?

I also greatly enjoy reading GBD ’s knowledgeable and informative contributions about Concorde - some of which remind me just how much I’ve forgotten since 2003! If I may add a few comments to the points GBD and others are making: … It was a job of work when TCAS became mandatory … Yes indeed! And ...

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by kalvado
Mon Oct 17, 2022 3:06 pm
Forum: Technical/Operations
Topic: US$ Quantification of Aerodynamic Deterioration – Airbus Performance Audit Document
Replies: 3
Views: 1795

Re: US$ Quantification of Aerodynamic Deterioration – Airbus Performance Audit Document

Almost surprizing how seemingly tiny issues do affect performance. I wonder how these numbers are obtained - wind tunnel, simulations, something else?

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by kalvado
Sat Oct 15, 2022 9:55 am
Forum: Technical/Operations
Topic: Pulling jetways back from RON aircraft.
Replies: 16
Views: 3174

Re: Pulling jetways back from RON aircraft.

You mean on the aircraft doors? Might have safety implications. Consider someone forgetting to unlock them all before flight etc etc. Don't see it happening. As any change of paradigm, this may be a can of worms - but "forget to unlock" is definitely not the biggest issue. If slide cannot...

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by kalvado
Fri Oct 14, 2022 11:27 pm
Forum: Technical/Operations
Topic: Pulling jetways back from RON aircraft.
Replies: 16
Views: 3174

Re: Pulling jetways back from RON aircraft.

TSA is in charge of airport security?, yet insists on airbridge removal because 0f what? People are on the ramp that are suspect? Don't they screen everyone that gets an airside pass? Don't you need an airside pass to open the gate to the jetway?. Sounds like belt and braces to me. What about acces...

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by kalvado
Thu Oct 13, 2022 9:03 pm
Forum: Technical/Operations
Topic: Pulling jetways back from RON aircraft.
Replies: 16
Views: 3174

Re: Pulling jetways back from RON aircraft.

For some airlines, it's a security requrement if either the access to the jetbridge from the gate, or the access to the jetbridge from external stairs don't have some type of lock on the doors. If this is the case, the jetbridge must be pulled from the aircraft to prevent unauthorized access. This ...

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by kalvado
Wed Oct 05, 2022 3:40 pm
Forum: Technical/Operations
Topic: concorde with more than 100 passenger?
Replies: 27
Views: 4438

Re: concorde with more than 100 passenger?

I was always under the impression that weight on Concorde was a major consideration. If so, one has to wonder not that it could carry 128 passengers, but could it lift the extra 28 passengers? Then, carrying them, would it have sufficient range to fly anywhere worthwhile with a 3000 Kg fuel hit? Co...

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by kalvado
Wed Oct 05, 2022 12:30 pm
Forum: Technical/Operations
Topic: concorde with more than 100 passenger?
Replies: 27
Views: 4438

Re: concorde with more than 100 passenger?

With Concorde being very fuel thirsty.... Would those extra pax have too much effect on the range?

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by kalvado
Thu Sep 29, 2022 10:53 pm
Forum: Technical/Operations
Topic: FAA approves Gami100UL for entire piston engine fleet
Replies: 39
Views: 5686

Re: FAA approves Gami100UL for entire piston engine fleet

Low RPM, I agree with, but Lycoming and Continental compression ratios are nothing to be excited about—7:1 to 9:1 typically. Any car today with electronic controls is much higher—11:1 often. Brake Mean Effective Pressure (BMEP) might be a difference in the two applications. The lack of approved ele...

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by kalvado
Wed Sep 21, 2022 12:47 am
Forum: Technical/Operations
Topic: Technical=Arithmetics question
Replies: 11
Views: 1540

Re: Technical=Arithmetics question

10 statute miles up in the air is more like 52800 feet. Darn! I thought it would actually be much, much lower!! Like, maybe 5 or 10 thousand feet? :lol: Thanks man! Is this sarcasm or did you really think a statute mile was a 1,000’? Since 1 kilometer is 1000 meters, it should be a plausible assump...

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by kalvado
Thu Sep 08, 2022 8:37 pm
Forum: Technical/Operations
Topic: 737 Max 9 performance
Replies: 31
Views: 8264

Re: 737 Max 9 performance

If the runway at SAN was a factor, United would sure be having a hard time with their 7M9s out of OGG. This had to do with the weather in MCO and nothing else. Lol, no. Lol, yes. The MAX really is a runway hog, even with 28k engines. It's easy to see the max9 running into tow restrictions from SAN ...

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by kalvado
Wed Sep 07, 2022 12:36 pm
Forum: Technical/Operations
Topic: International flights arriving a day before
Replies: 9
Views: 2055

Re: International flights arriving a day before

Further to info posted, this is also why most airlines adhere to UTC time for internal purposes. Keeps things uniform. Was always fun explaining to new hires that tonight’s flight is actually on the schedule as tomorrows, and so on. But could be a bit challenging to understand, especially when conv...

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by kalvado
Mon Sep 05, 2022 9:12 pm
Forum: Technical/Operations
Topic: FAA approves Gami100UL for entire piston engine fleet
Replies: 39
Views: 5686

Re: FAA approves Gami100UL for entire piston engine fleet

Mixed xylenes are a hugely important, ever growing, petrochemical product at the moment. Asia-Pacific is building dedicated units: crude oil in => paraxylene out. In millions of tons each. China is big on these. Demand for polyester (bottles and fibres) drives that. What kind of volumes in Avgas ar...

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by kalvado
Mon Sep 05, 2022 8:39 pm
Forum: Technical/Operations
Topic: FAA approves Gami100UL for entire piston engine fleet
Replies: 39
Views: 5686

Re: FAA approves Gami100UL for entire piston engine fleet

Do you understand the ridiculous amount of testing that has gone on? Lead itself is an additive...to increase octane. I don't see how you don't believe "cheaper as production scales up." It is all about economies of scale. Indeed, this stuff may well have more applications than aviation, ...

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by kalvado
Mon Sep 05, 2022 8:08 pm
Forum: Technical/Operations
Topic: FAA approves Gami100UL for entire piston engine fleet
Replies: 39
Views: 5686

Re: FAA approves Gami100UL for entire piston engine fleet

If they did, 100LL, 100R or G100UL would be irrelevant to the discussion. Incidentally, the guys at GAMI found that G100UL outperforms even the old 115/145 Purple Avgas that was used in Constellations and DC-7s. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&...

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