Do 8A's tip over (flip) too?

[cytoxin]

moving the cg aft makes it land nose high because you move it to far from the center of lift.????? uh huh i think

[RVbySDI]

Originally Posted by allbee

Now to get into another possibility. How about center of gravety on the A models. Too far back and the nose wheel takes the load.

I believe I understand what you are saying and what others are confused about from your post.

You are referring to moving the point where the landing gear are attached to the fuselage. The further back the main gear are mounted the more weight the nose gear will be required to support when the airplane is on the ground. This is what I am getting from your statements. If this is what you mean, that is not necessarily a component of CG in relation to the wing and what the wing supports, which is what most people think about when discussing CG.

[Harvey L. Sorensen]

I believe you have it Steve.
The airport where I have my 9-A will close for repairs for about three months starting in June. I have my own strip at my home but it is fine for my J-4 Cub. I can check for critters homes ect and bring in my 9-A and I am thinking coming in and out of this grass strip with around 80 pounds of wieght in the luggage just to help keep the nose wheel off the ground longer. This will move the CG to the rear a lot and make the nose lighter. I have a 320 with a Hartzel CS.
Am looking for comments either for or against. I don't really like to do the grass thing but there are no hangers at any of the other local airports.

[RVbySDI]

Well Harvey, I can see where an aft CG will help keep weight off of the nose gear when taking off. I would just make sure you are not going to load up with aft CG and fly off enough fuel that the CG will push even further aft (not saying this is what would happen with the fuel burn in the 9A but some airplanes do). As long as your CG remains within the parameters of the airplane and you can maintain full control you should be good.

These nose gear threads are very interesting to me as I am building a 9A and have a hangar on a private grass strip where I intend to fly out of. I want to do whatever it takes to assure that I can reduce my risks of a nose gear failure. If it is proven that the 9A will not perform on grass without high risk then I will be forced to re-examine my decision to fly the -A.

[allbee]

Ok guys, you need to go back to the basics on flight. CG is the force on the underside of the airframe. This is invisible. Emagine a point that is a force on the underside of the airframe when the aircraft is FLYING. If this force is aft the nose of the airframe WILL be heavy, if this point is forward the tail WILL be heavy. The best way to understand this is to do all your computations for weight and balance and figure out your CG (center of gravity), then mark your center of gravety on the wings, then put some jacks under wings at this point and raise the aircraft, if you done things right the airframe WILL balance with no drop in the front or back, if it does something different, the weight and balance was not figured right.

Question, how many people weigh their baggage? I don't mean to put it on a bathroom scale. What I do is use a fish scale and weigh each item I put in the aircraft and note where in the aircraft I put them.

[rv7boy]

Originally Posted by allbee

...I have a trainer plane for remotes and if I put the cg forward than I can impress people at the field and land with nose off all the way to the pit. If I put the cg aft, forget it, can't do it.

Now my kitfox, if I have stuff in the back, luggage. Than it flies more nose high on landing. I'm sure the same is for the A models as well...

Steve, I just returned from lunch and have read your replies and those of others, and apparently we are talking past each other. Perhaps, we are speaking a different language. Your two paragraphs above are in conflict, unless I understand you to mean you are moving your landing gear forward to impress people at the field. This is not what I call moving the CG forward. Putting weight in the nose (as I used to do on TAILHEAVY RC models) moves the CG forward and puts more weight on the nose when the model is sitting at rest.

If you can get a copy of the excellent book, "Aerodynamics for Naval Aviators" and read the section on Longitudinal Control on pages 275-278, I think you would find it an interesting read.

I do know that if I put extra weight in the back compartment of my 172, behind the mains and without moving the mains, it makes the nose wheel support less weight.

All the best,
Don

P.S. Having just read the Allbee post that was written while I was composing my post, I see we are indeed talking past each other. I too have balanced many RC airplanes, not to mention calculated weight and balance on many 150's, 172's, Warriors, etc. I have decided to not continue my end of this discourse. Again, best wishes!

[L.Adamson]

Originally Posted by RVbySDI

These nose gear threads are very interesting to me as I am building a 9A and have a hangar on a private grass strip where I intend to fly out of. I want to do whatever it takes to assure that I can reduce my risks of a nose gear failure. If it is proven that the 9A will not perform on grass without high risk then I will be forced to re-examine my decision to fly the -A.

Ask Jerry Thorne. He does occasional posting/replies here, and has flown an RV9A from a grass strip for quite awhile.

Note: I tried to copy his website address, but it didn't work. Search here or google.

L.Adamson

[jcoloccia]

John's simple view of the world:

CG as we calculate it not the whole story when the plane's on the ground. You must also consider the location of the mains and nose gear. All things being equal, moving the CG aft will unload the nose gear. Eventually, the CG will be right over the mains and the nose gear will support exactly 0.....and move a little further than this the tail will drop and the nose will be in the air.

On the other hand, moving the CG back by adding weight will not necessarily unload the nose. Since the mains are always behind the CG, you can move the CG back with weight but actually load the nose gear MORE. Any ounce you add in front of the mains will be some fraction of an ounce felt on the nose gear.

So you're all correct....sorta.

[cytoxin]

the center of gravity is the point at which anything balances...if my plane balaces at 27% the mean aeordynamic chord than i put weight in the back the cg moves aft resulting in less weight on the nose wheel.

[combat404]

Is the engine mount/nose gear on the RV-10 stronger and less prone to flipping? Can it be used on 2 seat RV's?

Thank you.

Ron