just a follow up on your vanessa cg rig...built one..works great for most of my planes...only issue I want to touch on...level on the rear stab...before cg stuff...how do you establish what IS LEVEL when hanging plane...(most rear stabs are CURVED a bit) egs..P51.... so level varies on where ON the rear stab you put this level ...is it basically an eyeball thing??? ps..I hung a small weight on fishing line the same weight as the level (7grms} on the nose to equal out weight of the little level
An airfoiled surface like on bigger planes can be a bit tricky, but what you could do is find the center of the horizontal stab at the tip on the leading and trailing edge and mark a line along the center. Then find a way to put the level along that line and use that to level the plane. That's a great idea by hanging the weight on the nose, I'll have to try doing that.
So...what about the center of lift of the wing vs. center of gravity of the airplane? Do you know anything about the center of lift of a ram air wing? I'm not trying to be a smart ass, but I really want to know this stuff, since I plan to design and build a full-scale version of a wing-in-ground effect craft, that I can climb aboard and fly in person. I really don't want to die the first time I try fly it. Any knowledge you can share would be very appreciated.
Yes, and that's the point. Once the model is level, whatever you are using as a pointer will show the current CG. If the CG is in the wrong place or not where you want it, you add weight to either the nose or tail and then twist the dowel to level the model again. Continue to do this, (add weight, twist dowel), until the model is level and the pointer is showing the CG where you want it to be.
Having a tailplane that has an airfoil shape complicates this a bit, but thanks for the video as it will apply to the other 90% of RC models that are provided with a GC location. it does tick me off that I was given "a range" of millimeters from the leading edge for the CG of my Wargo Yak. I still haven't got it flying reliably..
The plane does not have to be perfectly level for this to work, so, practically speaking, you can forget about the spirit level. Just eyeball it from the side and adjust the plane so it's close to the attitude it assumes in level flight, and you will be good to go.
+Danger Dan What this method does is tell you where the current CG is. So, to answer your question, no, it doesn't. You would have to go through the process of measuring the wing chord, etc., to find where the correct CG should be then balance the model accordingly.
if I read correctly..this gets rid of flipping plane up-side-down...I.should STILL retract gear..right....Im buildind this...(trying to flip a twin engine mosquito..gear up..battery installed..& using fingers..lol TRY THAT!!!).. this looks bang on bud
That is correct, plane right side up, gear retracted. It should still work even if the plane is upside down but there is not need for it. I have used it for several different planes, (high, mid and low wing; with and without retracts), and it works for them all with the plane right side up.
Thanks, very cool..very simple..got so frustrated trying to balance a fairly large plane on the machine I built out of pbs pipe...real gong show...got this built, just have to get a small plum bob..
I made one of the machines and it works well. Thanks. The only problem I have found is determining the point to put the spirit level on. Most stabilizers are curved and finding the point where you are at zero degree incidence is a bit hit and miss unless you have an incidence machine. Using an incidence machine I generally can find a point on the plane which is the same, and this often is the battery/Rx tray. Any ideas?
as close to CG as possible would be the best place for it, some kind of foam holder will work great in case the aircraft is curved, a little messing about before hand so set the holder up, place the model on a soft cushion to complete this, once done you can keep the holder for future testing.
Yes, which is what this does if you know where the CG is supposed to be or where you want it to be. This is actually very simple and works great on bigger airframes since you aren't trying to balance it on your fingers or a flimsy post.
I tried this but the dowel pointed at the trailing edge of one wing and the leading edge of the other wing how did you keep the dowel parallel with the wing
Not sure what would cause that, never seen it happen. Make sure the cord loops are the same length and the number and direction of wraps are the same. You should be able to adjust the way the cords wrap around the wing to get the dowel parallel along each wing. Any chance you have a picture to show what you are seeing?
@@tsawyer148 i realized i had the dowels 90 degrees from support line. so i redid it like your video shows how important is it to have the loops that go around thw wings the s@me length and if it is important how did you tie them to the same length
The loops need to be the same length so the wings stay level horizontally. Just cut two pieces of whatever you are using for the cords and tie the knot the same way in the same place on the cords. You also need to make sure the wraps are going the same direction around the adjustment dowel like it says in the video.
That's what happens when your plane is going between 110 and 120 mph around a couple of pvc pipes at around 20 feet off the ground and someone elses plane tries to occupy the same space you are in. A result of Warbird pylon racing, and, as a side note, the plane was balanced perfectly thanks to this little item and flying like a bat out of hell.. :)
