5 ms·

I'll admit to complete and total ignorance, but: > ...we just use the number the manufacturer publishes. From the article it sounds like this plane was radica

I'll admit to complete and total ignorance, but: > ...we just use the number the manufacturer publishes. From the article it sounds like this plane was radically modified, to the point where the manufacturer's stall speed would be irrelevant. Why wouldn't you want to confirm for yourself where the speed is after so many changes?

hluska 3y ago
The plane had a cargo pack and a Robertson STOL. Cargo packs are essentially for bush planes and as an example, the 1975 Skywagon’s owners manual even had one diagrammed. Robertson STOL’s are extremely common in Northern Canada to the point that even as a passenger I know about them. It’s nothing too radical. Edit - Here’s a copy of the 1975 owners manual: https://www.seaplanescenics.com/documents/1975-cessna-185f-poh-1.pdf https://www.seaplanescenics.com/documents/1975-cessna-185f-p...
jcalvinowens 3y ago
My understanding is that in the US, part of the modification would be updating the plane's official operating limitations, and there could be a new stall number. Still a number from the manufacturer, not a number empirically determined by testing that specific airplane. For special one-off modifications, I don't know: I've always been told that's almost impossible with certified airplanes. One Citabria I've flown had vortex generators installed on the leading edge of the wings, but the club sold it over a year ago and I don't remember if it listed a modified stall speed. I do remember it said "not airworthy if more than N of the VGs are broken off", I think it was three?
dghlsakjg 3y ago
Stall speed depends on so many factors that it can change significantly in a single flight. Weight, altitude, density altitude, angle of attack etc. are all going to have an effect. In other words, sure, you might want to confirm it, but you should also give yourself some margin since you don’t ever really know what the stall speed is until you stall.
- WalterBright 3y ago
  Don't forget ice!
  - greedo 3y ago
    And temperature...
- BruinsInSeven 3y ago
  How do you determine a margin without some form of a baseline?
  - dghlsakjg 3y ago
    You read the operator’s handbook which will give you that information. In a certified aircraft the manufacturer has already done the test flying
    - ryandrake 3y ago
      Your airplane can also be in the "experimental" category, which generally means "homebuilt" so the stall speeds and characteristics can only be determined through test flight. I made the decision to empirically demonstrate stall speeds on the very first flight of my homebuilt, before attempting to land, so I knew for sure what they were.
      - dghlsakjg 3y ago
        I also have a homebuilt, and went and found out my stall speed. But most homebuilts will still have a stall speed for planes built to plan. In any case, this is an article about a Cessna. Where the stall speed is in the POH and also marked on the ASI.
  - deleted 3y ago
    [deleted]
- KolmogorovComp 3y ago
dramm 3y ago
Radical has all the wrong implications. It's a "major alteration" in a regulatory sense, done from an approved kit of parts, with a very well documented installation and post-installation operation and maintenance procedures. The aircraft was modified with a Robertson STOL kit. A common type of modification to make to a "bush aircraft". In the USA the modification is covered by an STC (Supplemental Type Certificate), the installation needs to be supervised and approved by an A&P technician with IA (Inspection Authority). The STC will modify the airspeed indicator markings, including the stall speed markings (bottom of green and white arcs), and modify the approved flight manual/pilot operating handbook and maintenance documentation for the aircraft. Since this is a major alteration (in a 14CFR regulatory sense) that modifies the flight characteristics of the aircraft it needs to be test flown after the work, and the STC will also separately requires this. I expect/hope the STC includes instructions for checking stall characteristics including airspeed. In European countries a similar level of regulation/documentation is followed based on the USA STC. Give the description of the pilot's sad lack of understanding of basic operation of the aircraft I am doubting they even read the pilot operating handbook.
- avianlyric 3y ago
  As noted in the article, the plane had been modified with far more than just the STOL kit. > A further issue was that his Cessna 185 had been extensively modified. The addition of floats, cargo pack, short take-off and landing kit and a three-blade propeller had never had their combined effect documented. That’s a lot of things that modify the flight characteristics of a plane, all interacting together in what seems to be a previously untested configuration. I can completely see how each individual modification might modify the planes flight characteristics in a well know manner. But I struggle to see how anyone could realistically predict the result of all the modifications without some basic empirical testing.
  - dramm 3y ago
    A three bladed prop modification along with floats is very common. Wipaire, the leading float manufacturer has its own STC for that. In combination with STOL kits is not uncommon either. I expect the Robinson STOL STC explicitly accommodates floats (Wipaire’ STOL STC sure do) but not sure since I don’t have the paperwork in front of me. You are over inflating issues here. Are you a pilot? The issue here is straight up incompetent operation of an aircraft. Operating a floatplane and separately operating with a STOL kits can increase complexity and risks especially when aircraft are mishandled/abused like here with an incompetent pilot who does not know what they are doing. You don’t need to dream up issues from combination of stuff here, the simple linear addition of issues was more than enough for an incompetent pilot to get into trouble, and seems they are lucky they did not get into more trouble before, and lucky they were not killed. The C185 is a beautiful well behaved workhorse used extensively in bush and floatplane flying, often with multiple STCs to upgrade these aircraft.

hluska 3y ago

The plane had a cargo pack and a Robertson STOL. Cargo packs are essentially for bush planes and as an example, the 1975 Skywagon’s owners manual even had one diagrammed. Robertson STOL’s are extremely common in Northern Canada to the point that even as a passenger I know about them. It’s nothing too radical. Edit - Here’s a copy of the 1975 owners manual: https://www.seaplanescenics.com/documents/1975-cessna-185f-poh-1.pdf https://www.seaplanescenics.com/documents/1975-cessna-185f-p...

jcalvinowens 3y ago

My understanding is that in the US, part of the modification would be updating the plane's official operating limitations, and there could be a new stall number. Still a number from the manufacturer, not a number empirically determined by testing that specific airplane. For special one-off modifications, I don't know: I've always been told that's almost impossible with certified airplanes. One Citabria I've flown had vortex generators installed on the leading edge of the wings, but the club sold it over a year ago and I don't remember if it listed a modified stall speed. I do remember it said "not airworthy if more than N of the VGs are broken off", I think it was three?

dghlsakjg 3y ago

Stall speed depends on so many factors that it can change significantly in a single flight. Weight, altitude, density altitude, angle of attack etc. are all going to have an effect. In other words, sure, you might want to confirm it, but you should also give yourself some margin since you don’t ever really know what the stall speed is until you stall.

WalterBright 3y ago
Don't forget ice!
- greedo 3y ago
  And temperature...
BruinsInSeven 3y ago
How do you determine a margin without some form of a baseline?
- dghlsakjg 3y ago
  You read the operator’s handbook which will give you that information. In a certified aircraft the manufacturer has already done the test flying
  - ryandrake 3y ago
    Your airplane can also be in the "experimental" category, which generally means "homebuilt" so the stall speeds and characteristics can only be determined through test flight. I made the decision to empirically demonstrate stall speeds on the very first flight of my homebuilt, before attempting to land, so I knew for sure what they were.
    - dghlsakjg 3y ago
      I also have a homebuilt, and went and found out my stall speed. But most homebuilts will still have a stall speed for planes built to plan. In any case, this is an article about a Cessna. Where the stall speed is in the POH and also marked on the ASI.
- deleted 3y ago
  [deleted]
KolmogorovComp 3y ago

dramm 3y ago

Radical has all the wrong implications. It's a "major alteration" in a regulatory sense, done from an approved kit of parts, with a very well documented installation and post-installation operation and maintenance procedures. The aircraft was modified with a Robertson STOL kit. A common type of modification to make to a "bush aircraft". In the USA the modification is covered by an STC (Supplemental Type Certificate), the installation needs to be supervised and approved by an A&P technician with IA (Inspection Authority). The STC will modify the airspeed indicator markings, including the stall speed markings (bottom of green and white arcs), and modify the approved flight manual/pilot operating handbook and maintenance documentation for the aircraft. Since this is a major alteration (in a 14CFR regulatory sense) that modifies the flight characteristics of the aircraft it needs to be test flown after the work, and the STC will also separately requires this. I expect/hope the STC includes instructions for checking stall characteristics including airspeed. In European countries a similar level of regulation/documentation is followed based on the USA STC. Give the description of the pilot's sad lack of understanding of basic operation of the aircraft I am doubting they even read the pilot operating handbook.

avianlyric 3y ago
As noted in the article, the plane had been modified with far more than just the STOL kit. > A further issue was that his Cessna 185 had been extensively modified. The addition of floats, cargo pack, short take-off and landing kit and a three-blade propeller had never had their combined effect documented. That’s a lot of things that modify the flight characteristics of a plane, all interacting together in what seems to be a previously untested configuration. I can completely see how each individual modification might modify the planes flight characteristics in a well know manner. But I struggle to see how anyone could realistically predict the result of all the modifications without some basic empirical testing.
- dramm 3y ago
  A three bladed prop modification along with floats is very common. Wipaire, the leading float manufacturer has its own STC for that. In combination with STOL kits is not uncommon either. I expect the Robinson STOL STC explicitly accommodates floats (Wipaire’ STOL STC sure do) but not sure since I don’t have the paperwork in front of me. You are over inflating issues here. Are you a pilot? The issue here is straight up incompetent operation of an aircraft. Operating a floatplane and separately operating with a STOL kits can increase complexity and risks especially when aircraft are mishandled/abused like here with an incompetent pilot who does not know what they are doing. You don’t need to dream up issues from combination of stuff here, the simple linear addition of issues was more than enough for an incompetent pilot to get into trouble, and seems they are lucky they did not get into more trouble before, and lucky they were not killed. The C185 is a beautiful well behaved workhorse used extensively in bush and floatplane flying, often with multiple STCs to upgrade these aircraft.