Negative G Load Question
Moderators: sky's the limit, sepia, Sulako, lilfssister, North Shore, I WAS Birddog
-
- Rank 3
- Posts: 152
- Joined: Mon Jun 29, 2009 1:42 pm
Negative G Load Question
I'm trying to find a reputable source that explains how aircraft are certified or not certified for negative G loads. The scenario I'm looking at is if you get look at a POH for an aircraft and it shows a Max. G Load of +3.5 but no negative G load limit. Does that mean that aircraft is restricted to manoeuvres between 0 G and +3.5 G or would it mean that no G loading below 1 would be permitted? I'm thinking it would be between 0 and 3.5 but not sure. Thoughts?
Keep your stick on the ice - Red Green
Re: Negative G Load Question
A GA aircraft certified as "CAR 3" or "FAR 23" will be certified as follows:
Your challenge is measure the G forces! Unless you have a G meter, you're just guessing anything negative.
Bear in mind that though the airframe can take the negative G, the engine oil system and battery won't like it much. You'll also get dirt from the floor up you nose! Avoid fooling around in the plane with negative G, unless you have a G meter, some training for that, and are ready to clean the belly afterward.
Commonly that works out to +3.8G, -1.5G for a normal category plane. In addition to that is the specified factor of safety, which means that up to 1.5 times those values, the plane will not break, though you might bend something expensive.Sec. 23.337
Limit maneuvering load factors.
(a) The positive limit maneuvering load factor n may not be less than--
[(1) 2.1+ for normal and commuter category airplanes, where W = design maximum takeoff weight, except that n need not be more than 3.8;]
(2) 4.4 for utility category airplanes; or
(3) 6.0 for acrobatic category airplanes.
(b) The negative limit maneuvering load factor may not be less than--
(1) 0.4 times the positive load factor for the normal, utility, and commuter categories; or
(2) 0.5 times the positive load factor for the acrobatic category.
(c) Maneuvering load factors lower than those specified in this section may be used if the airplane has design features that make it impossible to exceed these values in flight.
Your challenge is measure the G forces! Unless you have a G meter, you're just guessing anything negative.
Bear in mind that though the airframe can take the negative G, the engine oil system and battery won't like it much. You'll also get dirt from the floor up you nose! Avoid fooling around in the plane with negative G, unless you have a G meter, some training for that, and are ready to clean the belly afterward.
Re: Negative G Load Question
Is to reduce negative G loading the reason water bombers deploy full flaps duing the dump?
The average pilot, despite the somewhat swaggering exterior, is very much capable of such feelings as love, affection, intimacy and caring.
These feelings just don't involve anyone else.
These feelings just don't involve anyone else.
Re: Negative G Load Question
Agreed. Floating in the straps gives most people a head rush and makes them think they're doing something extreme. -2 will scare the bejeezus out of them and all but guarantee they never fly again.cgzro wrote:Trust me youll know when you go past -2g
Re: Negative G Load Question
Yeah, I had to do flight testing for engine operation to exactly -1G a few times, I don't like that stuff!
An old friend of mine some time ago was telling me about flying jet fighters, and how tight the cockpit was. "What did you do if you dropped your chart?" I asked... He replied "simple, roll upside down, and pick it up off the inside of the canopy!". Better he than I!
An old friend of mine some time ago was telling me about flying jet fighters, and how tight the cockpit was. "What did you do if you dropped your chart?" I asked... He replied "simple, roll upside down, and pick it up off the inside of the canopy!". Better he than I!
Re: Negative G Load Question
Negative G beyond -2 is basically painfull but you do get used to it.
Actually the worst is a rapid change from one extreme to the other. Most people never experience this but when a plane is rolled and turned at the same time you go +3/-3 multiple times in a row. Ouch.
Actually the worst is a rapid change from one extreme to the other. Most people never experience this but when a plane is rolled and turned at the same time you go +3/-3 multiple times in a row. Ouch.
Re: Negative G Load Question
Can any of the aerobatic guys tell if your allowed to go from either positive to negative or vice versa because of the possible "g LOC"?
I though an airshow official explained that was not allowed. the example was an inverted climb with a pull back onto the showline.
I though an airshow official explained that was not allowed. the example was an inverted climb with a pull back onto the showline.
Re: Negative G Load Question
It's called "push pull" effecttarget wrote:Can any of the aerobatic guys tell if your allowed to go from either positive to negative or vice versa because of the possible "g LOC"?
I though an airshow official explained that was not allowed. the example was an inverted climb with a pull back onto the showline.
And I have no idea if it's allowed, but I would suggest that it's not a great idea to do it. It severely reduces G capacity due to your body compensating for - g and then rapidly switching to + g. Your blood vessels dilate and can't constrict fast enough to give you g tolerance.
Re: Negative G Load Question
Its required in contests above intermediate and allowed in airshows. We call them sleepers.
You need to be in good shape and know your limits and despite popular myth you dont just suddenly pass out, you get a bit or warning and backing off the G instantly will cure it assuming you are not in need if that pos G to avoid the ground. Negative followed by pos to recover close to ground would be something to approach with caution. He who shall not be named's father flew a lovely series of inside outside vertical 8 cominations at Gatineau a few years ago when well north of 70... impressive.
You need to be in good shape and know your limits and despite popular myth you dont just suddenly pass out, you get a bit or warning and backing off the G instantly will cure it assuming you are not in need if that pos G to avoid the ground. Negative followed by pos to recover close to ground would be something to approach with caution. He who shall not be named's father flew a lovely series of inside outside vertical 8 cominations at Gatineau a few years ago when well north of 70... impressive.
Re: Negative G Load Question
Who would that be? Beelzebub?He who shall not be named's father flew a lovely series of inside outside vertical 8 cominations at Gatineau a few years ago when well north of 70... impressive.
Rule #62 "Don't take yourself so damn seriously"
-
- Rank 5
- Posts: 357
- Joined: Fri Jan 14, 2005 12:18 am
- Location: Prince George
Re: Negative G Load Question
Colonel Beelzebub, I'm guessing.duCapo wrote:Who would that be? Beelzebub?He who shall not be named's father flew a lovely series of inside outside vertical 8 cominations at Gatineau a few years ago when well north of 70... impressive.
Re: Negative G Load Question
It's amazing how your G tolerance drops when doing quick transitions from +G to - and back. You certainly build a tolerance with exposure. My first few flights each season are brutal.