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ERAU Aerodynamics Project (PA-18-150), G-Force

stevie-b

Registered User
Baker, FL
Greetings everyone,

First post, but I have been parsing this forum often in the past few weeks of my Aerodynamics class at ERAU and have gotten a lot of good information here and there through various posts--various POH links and User Manual for general data, as well as reading through some of your seasoned pilot comments! I am currently working on a group project where we selected the PA-18-150 with the USA 35B airfoil to run our numbers on. I won't ask for too much as I now can tell this aircraft has many configurations--as well as using the search bar! However, when searching for G-force, Load Limits and other limitations--I only seem to turn up weight and balance info (which I will definitely use next week)!

My pointed question has to do with G-force for our week covering "maneuvering performance". I understand that 14 CFR 23 & 25 require civilian aircraft to be designed to meet or exceed specific G force ratings, and those values are listed in a table depicting G numbers for Normal, Utility, Cargo, and Aerobatic. I created a VG table and diagram just going with the "Normal" category force ratings listed in our lecture (+3.8 and -1.5 Gs), but if anyone knows more general "Super Cub" numbers, I would like to tighten up my calculations/charts if able. Being that a cub is a variance of weights, steel tubing/wood/canvas and or a mixture therein--I would guess the rating will vary by configuration and how it is specifically categorized?

Overall, I thank you for your time and any input,

Steve
 
Be aware the the Cub was certified under CAR3, not FAR 23. You'll need to check the numbers in that reg.

Web
 
What Web posted and realize that the only wood in a Super Cub is the wing tips, floor boards and on the older ones the fuselage stringers.
 
My mistake! I when I was looking through one of the forums, someone made a post about some structural damage to their ribs with pictures. I assumed there was a mix of wood and metal tubing in the entire construction of the wings.
 
Be aware the the Cub was certified under CAR3, not FAR 23. You'll need to check the numbers in that reg.

Web

I'll search the library for the historical on that--again in my assumptions I figured newer variants would not fall under CAR 3 1949 Amendments but rather the updated FARs
 
I'll search the library for the historical on that--again in my assumptions I figured newer variants would not fall under CAR 3 1949 Amendments but rather the updated FARs

Steve, with the FAA, the certification basis is established about 5 years prior to the first aircraft being built, and remains the same for the entire production run, unless the manufacturer decides to update to a more recent set of regulations. There are airplanes still being built to the 1934 regulations. In the case of the PA-18, it was certified in November of 1949, so the applicable regulations would be the November 1945 version of CAR 3. The 1949 version that is on RGL.faa.gov will get you close enough. There weren’t that many changes from 1945 to 1949.


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Anyone searching in the future for the CAR 3, I believe I found a link... The actual FAA site lists all the sections, by does not have them hyperlinked to anything. I think because of my account age I am unable to post the link in the forum (error message "Post denied. New posts are limited by number of URLs it may contain and checked if it doesn't contain forbidden words.")
 
Try this

http://www.navioneer.org/riprelay/Ye.../car_part3.pdf

In all seriousness, every one of us in general aviation needs to maintain a copy of CAR 3. It is the certification basis for the vast majority of smaller aircraft and takes precedence over FAR 23 because of that. With rare exception, a repair or modification that meets the specs of CAR 3 is a legal one. In spite of what the local fed may say. Don't let the feds bury this reg. Copy it and share it.

Web
 
Rgl.faa.gov has a lot of the old reds, but not all. The DOT Special Collections library has a lot more, but you need to set up a log in.


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Try this

http://www.navioneer.org/riprelay/Ye.../car_part3.pdf

In all seriousness, every one of us in general aviation needs to maintain a copy of CAR 3. It is the certification basis for the vast majority of smaller aircraft and takes precedence over FAR 23 because of that. With rare exception, a repair or modification that meets the specs of CAR 3 is a legal one. In spite of what the local fed may say. Don't let the feds bury this reg. Copy it and share it.

Web

I keep printed copies of CAR 3 and 8 in the hangar. For whatever reason, FSDO once sent out their self described “corporate jet expert” to do an inspection on my 40 yr old spray plane, and he about had a stroke trying to understand a CAR 8 certified aircraft. It took that paper copy plus 2 IA’s to get him to leave without trying to write up a novel of violations.
 
I keep printed copies of CAR 3 and 8 in the hangar. For whatever reason, FSDO once sent out their self described “corporate jet expert” to do an inspection on my 40 yr old spray plane, and he about had a stroke trying to understand a CAR 8 certified aircraft. It took that paper copy plus 2 IA’s to get him to leave without trying to write up a novel of violations.

Geez! Sounds like some of the stuff I'm also going over in my Aero Law class as well... Basically being taught that anyone who talks to you can be an enforcement officer waiting to bait you into some sort of confession through regular conversation... and to ALWAYS consult an aviation attorney should you find yourself in their cross hairs... Don't worry, I am just an Army guy ready to retire, and getting an Aeronautics degree and a minor in Airport Management :)
 
Geez! Sounds like some of the stuff I'm also going over in my Aero Law class as well... Basically being taught that anyone who talks to you can be an enforcement officer waiting to bait you into some sort of confession through regular conversation... and to ALWAYS consult an aviation attorney should you find yourself in their cross hairs... Don't worry, I am just an Army guy ready to retire, and getting an Aeronautics degree and a minor in Airport Management :)

I used to teach aviation law years ago. If someone comes around asking questions, always ask if they are FAA or LE before answering. If asked, FAA inspectors can’t conceal that they are inspectors. In any case, if confronted by an inspector be virtuous, and don’t offer any info not asked for. Close the door to the airplane or hangar. They can’t enter unless invited or have a warrant. The aircraft record are never with the airplane (not required) and if they want to review them make an appointment some time in the future. Last, know the regulations better than they do. For anything they want to see or write a condition notice on, ask them to cite the specific regulation associated with it. If they can’t cut a regulation, tell them to go pound sand.


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ANY TIME a fed tells you that you must do something or that you cannot do something, get it in writing and ask for (demand) the FAR that governs that action. Never accept an explanation of 'I think it should be that way'.

Also understand that you can 'fire' an inspector. Just call his supervisor and tell them that you need another inspector instead. They can't force someone on you if there is bad blood.

And it shouldn't need to be reiterated, but as dga said, know the regs!!!! We can't protect ourselves from stupidity if we don't know the regs. We also have no excuse not to know the regs as they govern the aircraft operations and maintenance.

Web
 
I had a visit from an FAA inspector who had trouble reading a log book and who had delayed for two months after the mandatory 30 day option period in reviewing a 337, for sending it to OK city. I pointed this out to a friend who happened to be the top dog in the region. I never saw this particular inspector again. It seems he was transferred to Singapore. :p
 
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