Cessna tests new “Skycourier” and it’s actually not too terrible

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cluttonfred

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Cessna has had great success with the Caravan and Grand Caravan in multiple roles including military and law enforcement and I expect we will see them branching out to other roles as well for the Skycourier. Given the age of most utility turboprop twins out there (Twin Otter, Nomad, Islander, etc.), I think they will find a ready market not just in cargo and short-hop passenger hauling but also border patrol, maritime patrol, general ISR, mapping, even light assault transport, you name it, any activity in which the job or the terrain makes folks think they want two engines not one.
 

Twodeaddogs

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My experience is that accountants clamor for cost savings, but engineers find the cost savings.


BJC
An accountant will make the engineer use previously certified nuts/bolts/washers/knobs/levers,etc, rather than reinvent the wheel. The 737 cockpit is a case in point. A guy who flew a 737-200 could step into a Max and get it started in five minutes flat.
 

BJC

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An accountant will make the engineer use previously certified nuts/bolts/washers/knobs/levers,etc, rather than reinvent the wheel.
I’ve worked with lots of engineers; most good, but a few who were lacking. I never knew a good one who wanted to “reinvent the wheel” when an existing solution was available. Your experience might be with a different breed of engineer.


BJC
 
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Mad MAC

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When you consider how much of the aircraft is off the shelf parts, such as engines, avionics, every single nut, bolt and rivet, undercarriage parts, seats, floor hardware and so on, that is already certified, Cessna are left with building about 50% of the aircraft from new,which is essentially aluminium and composites, the technology is already well understood so the main cost is some original tooling and possibly a new factory.
You are a bit high, the general cost breakdown for most airframes is 1/3 for power plant, 1/3 for avionics and whats left for the airframe.

An accountant will make the engineer use previously certified nuts/bolts/washers/knobs/levers,etc, rather than reinvent the wheel.
Most projects don't have the time to invent new parts that can be brought off the shelf. One of the biggest causes of designing new parts is not being able to find the standard part in the first place (once you get away from the big primes, often the closest thing to a standard parts book is an IPC for similar sized airframes, or Aircraft Spruce etc).

We shan't mention the design office cry when designing turbo props of "what did Cessna do on the caravan"
 

Twodeaddogs

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I’ve worked with lots of engineers; most good, but a fe2 who were l@cking. I never knew a good one who wanted to “reinvent the wheel” when an existing solution was available. Your experience might be with a different breed of engineer.


BJC
what gets me about aircraft design is that different parts of the design team are clearly not talking to each other because the man who designs hatches must never have met the guy who designs the valve or pump or pipe that lives behind it, because you'd need to be a gynaecologist to work on some aircraft. I work on Airbuses and I find them to be pretty good for access, but they have their moments. I used to work on the BAE 146, which was some kind of a cruel joke for line maintainers. In fact, I think all aircraft designers should be scratched with locking wire or ty-raps or have their heads bumped off clamps or brackets repeatedly before they are allowed anywhere near an aircraft drawing board, so as to understand the consequences of their design process.😉
 

BJC

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I think all aircraft designers should be scratched with locking wire or ty-raps or have their heads bumped off clamps or brackets repeatedly before they are allowed anywhere near an aircraft drawing board, so as to understand the consequences of their design process.😉
Yup. The good engineers will find a way to get practical experience that is invaluable when they start a new design.


BJC
 

Angusnofangus

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what gets me about aircraft design is that different parts of the design team are clearly not talking to each other because the man who designs hatches must never have met the guy who designs the valve or pump or pipe that lives behind it, because you'd need to be a gynaecologist to work on some aircraft. I work on Airbuses and I find them to be pretty good for access, but they have their moments. I used to work on the BAE 146, which was some kind of a cruel joke for line maintainers. In fact, I think all aircraft designers should be scratched with locking wire or ty-raps or have their heads bumped off clamps or brackets repeatedly before they are allowed anywhere near an aircraft drawing board, so as to understand the consequences of their design process.😉
This is SO spot-on. I have cursed accessibility in aircraft too many times to remember.
 

BJC

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I enjoy working on airplanes, but I agree: lousy access makes it tedious and less fun.

BTW, a former neighbor (RIP) who was a full-time A&P - IA, always took the time to clip flush the Ty-wrap tails before starting anything else on an airplane. Saved lots of blood clean-up time.


BJC
 

Vigilant1

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Yup. The good engineers will find a way to get practical experience that is invaluable when they start a new design.
The USAF had (has?) a formal program to encourage this. Civilian acft designers spend a day on the flightline doing tasks on the existing fleet. The F-4 had some notoriously hard to access bellcranks and cannon plugs in the wings, each shift might only have one person with the arm length, dexterity, and "touch" to get things done right. Now, try it while wearing chem defense gear. In the heat. After a day af snaking their arms in and out of access panels, peering at things with mirrors on a stick, dropping fasteners deep inside inaccessible bays, etc a lot of engineers came away with an appreciation of the issues that book learning and specs can't provide.
 

BJC

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I recall that an F-117 wing broke off following an airshow fly-by. One of the attach bolts had been left out. Apparently it was very difficult to install it.


BJC
 

cluttonfred

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We shan't mention the design office cry when designing turbo props of "what did Cessna do on the caravan"
I am curious what you mean here, is it that they would be told not to innovate, just copy what Cessna did on the Caravan?
 

Vigilant1

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My FIL had a Mercury Bobcat. He said that the only way to change one of the rear spark plugs was to remove the air conditioning compressor. If accurate, I'm sure that's one spark plug that a wrench never touched (until the compressor was replaced, and I'd probably forget to do it).
 

Vigilant1

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I am curious what you mean here, is it that they would be told not to innovate, just copy what Cessna did on the Caravan?
I suspect that's "cry" as in "cry out," or "imploringly exclaim" rather than "weep."
 

Hephaestus

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It's called a "design study" isn't it? Engineers go look at similar "systems" to get a baseline understanding of what works (or doesn't) and what can be transferred to their project.

How many control systems can be traced back to the J3? We all do it and continue to do it almost daily. Every time we look over a set of plans and make mental notes "hey that's neat/different" then start deriving a new solution based on it.
 

Mad MAC

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I am curious what you mean here, is it that they would be told not to innovate, just copy what Cessna did on the Caravan?
A example of the design process & how does it relate to what cessna did se on the Caravan.

So you need a cowl latch, OEM's existing airframe doesn't use something acceptable, nearest existing airframes are Caravan, PC 6, 750XL, Kodiak. There's no one great index of aircraft hardware that is not MS etc, so you have to hunt for a supplier or P/N.

The Caravan has been built in volume & you can probably pick someones brain about how reliable the offending part is in service, plus you have got the IPC & Cessna could throw resources to produce a reliable design detail in the first place
The PC 6 is old & European, so sourcing similar part maybe problematic.
The 750XL & Kodiak are relatively low volume and IPC's are harder to get ones hands on.

So one tries to price out a cowl latch similar to that used on the caravan, cowl latch OEM comes back, send us 10K and we will design one just for you & I reply but we will only use 20 units a year, just sell us your cheapest or most common, sorry we only sell custom.

So what did I use, well there was a really nice automotive latch but wouldn't accomadate the arc motion of the cowl (using the well worn lie of, I want it for ground support equipment to get the relevent data) so ended up with the same one as used on a Hughes 500 clam shell doors with a moulded recess in the cowl (this bit wasn't my design, mine was to mount it in a stainless bracket bolted flush to the cowl, it would be less dragy and wouldn't be damaged liked composites meeting on the interface).

Cessna uses on the caravan quite a bit of componenty that comes from the biz jets that is quite pricey for the rest of us to buy but not always and some times its worth coping the parts in house.

The Cessna Latch
Hartwell H545-3.JPG
For those who collect parts
the automotive latch was Shop AeroCatch® 3 | Tension Latch with Shear Engagement Tongue
The final latch used Tension Latches - V18L01-1X1AA : Heavy Duty Adjustable Latch with secondary lock
 
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Angusnofangus

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A example of the design process & how does it relate to what cessna did se on the Caravan.

So you need a cowl latch, OEM's existing airframe doesn't use something acceptable, nearest existing airframes are Caravan, PC 6, 750XL, Kodiak. There's no one great index of aircraft hardware that is not MS etc, so you have to hunt for a supplier or P/N.

The Caravan has been built in volume & you can probably pick someones brain about how reliable the offending part is in service, plus you have got the IPC & Cessna could throw resources to produce a reliable design detail in the first place
The PC 6 is old & European, so sourcing similar part maybe problematic.
The 750XL & Kodiak are relatively low volume and IPC's are harder to get ones hands on.

So one tries to price out a cowl latch similar to that used on the caravan, cowl latch OEM comes back, send us 10K and we will design one just for you & I reply but we will only use 20 units a year, just sell us your cheapest or most common, sorry we only sell custom.

So what did I use, well there was a really nice automotive latch but wouldn't accomadate the arc motion of the cowl (using the well worn lie of, I want it for ground support equipment to get the relevent data) so ended up with the same one as used on a Hughes 500 clam shell doors with a moulded recess in the cowl (this bit wasn't my design, mine was to mount it in a stainless bracket bolted flush to the cowl, it would be less dragy and wouldn't be damaged liked composites meeting on the interface).

Cessna uses on the caravan quite a bit of componenty that comes from the biz jets that is quite pricey for the rest of us to buy but not always and some times its worth coping the parts in house.

The Cessna Latch
View attachment 97590
For those who collect parts
the automotive latch was Shop AeroCatch® 3 | Tension Latch with Shear Engagement Tongue
The final latch used Tension Latches - V18L01-1X1AA : Heavy Duty Adjustable Latch with secondary lock
Looks an awful lot like the cowl latches on Twin Otters. Same type used on 727 cowls IIRC.
 

Twodeaddogs

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The Gazelle helicopter had a list in the manual of acceptable automotive parts,such as the door handle, which was from a line of Renault cars. No-one batted an eyelid, because someone had taken responsibility early on,in Aerospatiale and said that this 10-franc door handle will do just fine and they still do the job to this day, even though the cars they were used on are long since obsolete. As another example, two days ago, I had a close look at the hardware of a very well known microlight kit, sold worldwide and all of it's hardware is Metric stainless steel bolts and not a single certified aircraft-grade bolt or nut in the entire aircraft. This aircraft, with a few mods,can also be approved as a Group A aircraft in Easa land. Now, the bolts are essentially no different to any automotive or hardware store bolt and you can't tell if they are first class or made of cheese. There is essentially no traceability,or if there is, I couldn't see it from the packaging. The aircraft is very successful, a delight to fly, well made and they sell as fast as the factory can pack them. So, who is doing it right? the aviation companies with back-to-birth tracability or a small microlight company, operating under the most stringent regulatory system in the world, with metric bolts of possibly untraceable origin. This is an LAA approved kit, so they (being a very stringent lot in their own right) must be happy with it.
 

Mad MAC

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The canopy latch on various Robin aircraft is a 2CV door handle.

There are two problems with automotive hardware, aircraft production runs vastly exceed automotive production runs, time wise & modern car components tend to be less adaptable than older components.

The issue with metric hardware is the modest number of shank lengths available which tends to add up to a bit of extra weight.
 

Dale_R

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This is SO spot-on. I have cursed accessibility in aircraft too many times to remember.
It's not just aircraft. When I was working as a field tech in the computer industry, I swore that if I ~ever~ got to be king-of-the-world, my first decree would be that no engineer would be allowed to design anything for production until they had served two years in residency as a repair tech.
 
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