Randy, it's really easy: If the CG's of your two planes are different in the way that your numbers predict, then your numbers are right. If the CG's of your two planes don't behave that way, then there's something wrong with your numbers.
Responsible engineers call this a sanity check. They do it all the time, because responsible engineers know that when you apply science to the real world, sometimes you mess up, and you need to check yourself each step of the way.
Responsible engineers do not get all bristly and defensive when they're colleagues try to help them with their sanity checks. That's because responsible engineers have no delusions about how close to God they are: they know that they are ordinary human beings just like everyone else. They also keep in mind all the engineering disasters* that they know of, to remind themselves that all engineers are human and that it's no crime to be off in one's numbers.
Since you're refusing to say what the CG positions are of the two planes, I can't say that your numbers are correct or not. But since I have a hard time believing that the well-known CG offset between electric and glow needs to be that much, and since you are getting all bristly and defensive to the point of refusing to share your knowledge of this simple point, then I can't say.
So -- your numbers don't seem to work out, and rather than sharing information about a simple check that would clarify things you're just repeating the same non-statements over and over again. I'm sorry that you're choosing this path, but until you share this simple tidbit of information that you hold, nothing more can be said about the accuracy of the numbers.
* Apollo 13, the Challenger, the Tacoma Narrows bridge, the Chevrolet Vega, the DeHavilland Comet -- the list is endless.
Tim
The numbers I am using are exact weights measured on a gram scale, and are correct
The locations are correct in as so much as the components can be moved, and in airplanes flying now have been moved around,
so there is no exact locked in place where you cannot move them, but you have to place them somewhere in the sheet.
The CG location is there, it is used to place the distances in the sheets I did, it is different in these 2 very similar ships because it needed to be for balance, as is the nose moment.
This is not an exerciser to find the CG of the planes, or how the CG acts . People who built and fly the ELC planes tell me that they fly with a more forward CG, I take their word for it .
Its Not a huge amount but still forward, I have flown many of them with the CG forward, including two of the that were the same plane, the turn seemed to be very close.
So the pilots are taking the same plane and moving the nose moment out longer, and running a more forward CG because they say the plane will balance more correctly and this is better than adding tons of lead in the nose of the ELC plane.
The CG of an ELC plane will move for several reasons..moving the battery fore and aft, handle size, CG "feel" for the individual pilot flying it, the notion that it needs to be farther forward and others.
The CG of the IC plane will move forward when actually flying the plane and adding fuel to do so, this weight will range from 4 to 8.5 ounces, I used the average weight of the fuel
Others such as Jose say that the CG is in the same location , So I guess that depends on how the pilot setups the airplane
The Cg location ,of the Ic is..as I have already told you is 3 to 3 3/4 inch aft of the center of the LE of the wing, if you need it from the TE I can give you that too, if you need it from the Prop I can also give you that number. IT is 12.5 to 12.8 inches. That is the numbers used in the sheet for placement.
It is not exact on every plane of the same type that anyone who setups their planes as some move it small amounts. The CG and nose moment on the same size ELC plane is farther forward because it was moved to balance the plane.
The CG of the ELC is approx 1/2 inch farther forward, but can be as much as an inch..note the same plane with a straight or swept forward TE will has a different CG location.
Now I also don't think there is that much difference in CG location when the IC plane has fuel in it, maybe 1/4 to 1/2 inch?? Who knows? Howard may have more exact numbers on his Impacts
To address your briskly commments, I am not getting briskly at all, I am trying my best to insert as accurate numbers as I can, and see what information can be gleemed out of them.
You on the other hand, looks like are only on this thread to try to cause me grief, and tell me everything is wrong. If your not interested in this why don't you just move on, or try to help.
And so far as you insinuating I am trying to hide something, I am not.
to addres this satement for you "
"Responsible engineers do not get all bristly and defensive when they're colleagues try to help them with their sanity checks. That's because responsible engineers have no delusions about how close to God they are: they know that they are ordinary human beings just like everyone else."
That is just an asinine , completely wrong statement and doesn't deserve any response.
As I stated earlier it also looks like this could be of help in converting or designing EC planes by putting the engine at a location that the numbers of the two are the same..or close, then you could adjust the battery..if needed.. back or forward to tweek the CG location. or you could use all total weights ,There maybe other information that could come from this that could be of use to people.
Randy
Topic: Number from calculations actual weights IC ELC. (Read 13736 times)