adding weight
 

Ive about got my sky raider mach 1 completed i checked the center of gravity tonight and its really light in the rearend i kept adding weight until i put 122 grams on the back before it leveled out seems like this is alot is this common to have to add this much weight and is it ok to put it on the bottom side of the fuselodge?Also when i measured the distance from the wing tip to the edge of the rear wing or the tail fin it was just a little shorter (1/2 inch) on one side will this make a difference or effect the flying?

RE: adding weight
 

I don't know how much it will effect it but it is a problem

RE: adding weight
 

[X(][X(] Wooow. That is a lot of weight you added. Before putting the lead, first move the battery and reciever towards the rear of the airplane, also make sure there is no gas on the tank, allways balance with no fuel on the tank... Allways try to move things around before adding the lead......:D:D

Regarding your misalignment, Im going to guess since the skyraider is an ARF, is that you glued the stab (rear little wing ), a little crooked. That will affect the airplane a little when applying the control surface (elevator), It will make it yaw just a bit.

RE: adding weight
 

Go back through the manual and double check the wing mounting instructions. You either have the wing not centered, or twisted on the fuselage. Mark the center on the wing and the fuselage and see if this helps. You shouldn't be able to twist the wing but that doesn't mean that it is impossible.

I had to go to Tower sight to see how 122 grams added up, the rest of us in KY use ounces. 4.3 ounces is too much, What engine/prop are you using? Is the wing seated on the fuselage as far forward as it can go?

You should measure the distance to the wingtips from a centerpoint on the tail of the aircraft. Your Hor. stabilizer could also be crooked.

RE: adding weight
 

Im useing a evo .52 and yes the wing is set all the way forward in the fuselodge sorry about the grams but it was marked on the tower hobby weights so i just added them up! But im like you that is alot of weight ! i dont have much room to move the receiver or battery back unless i put it on the other side of the servos. Just so you know this is my first try at a build like this!!!!!!

RE: adding weight
 

It's fairly common to need to place the battery and/or receiver behind the servos.

RE: adding weight
 

you should dry fit stab and then measure mark it then glue and measure again to make sure and yes you may have to move receiver and batt to the rear of servo's

RE: adding weight
 

misalignment
take a pin and stick it into top center of the front of fusalage, like on top of the firewall would be good.
attach a length of string long enough to reach the trailing edge (outer most tip) of the horizonal stabilizer.
mark the string with a dark marker,then check the opposite side to see if it is the same.

If it is then it is fine, and the wing is off center.
do the same on the wing with the attachement bolt or bolts in place
if the mark you make on the string at the trailing outermost wing tip on one side is different than the other, remove bolt and
adjust wing until you get the same measurement on both sides.
to fix the misalignment you may have to add to, or make a new attachment bracket.
dont forget to make a mark on the wing once it is centered.

the only way i know to fix the horizonal stab if it is off, would be to cut the hinges remove the elevator/halves and square the trailing edge of the stab. then make new hinge locations between the old ones, and reattach the elevator.
dont alter the elevator. it will be straight once the trailing edge of the stab is straight

the stab fix would be a lot of work, id wait and see first how well the plane will trim before making that dramatic fix.

center of gravity
for that type of plane a little nose heavy may not be critical, a plane is easier to fly nose heavy than it is if its tail heavy.
if after adding a little weight it is still very nose heavy, buy a wire extension and mount your battery as far back in the tail as possible.
you could remove the covering over a lightening hole and mount the battery to a bulkhead. run wire to receiver and recover the hole.

let us know how its going[8D]

RE: adding weight
 

G'day Mate,
The Skyraider Mk1 & 2 for that matter, have their horizontal tailplane ( you call it a stab) bolted on, the tailplane fits into a groove, so it is very difficult to get it on crooked.
The wing is also bolted on, so, if it is out of alignment, you may have messed up the holes in the wing.
It is only a trainer, so it does not fly at a million miles an hour so a bit of misalignment won't matter, as long as the bolts are tight, & screwed into the nuts set into the vertical fin.
One more point, I have put together 2 Skyraider Mk1's, the first one had the battery in front of the servos, to balance at 80mm behind the leading edge of the wing, with a 46AX, the second one, needed the battery behind the servos to get the balance point at 85mm, with the same engine & radio gear, this point through testing was the sweet spot for these aircraft, so the first one must have had either heavier wood in the tail, or the second one had heavier wood in the nose.
But move radio gear first, you should NOT have to add weight anywhere, these planes have been designed & built very well, & are a cinch to put together, if you follow the instructions.

RE: adding weight
 

Hi all,

I just maidened a skyraider mach 1 last weekend. Running a os 40 la it needed 3 ounces of lead in the nose. Yes I have the battery and the reciever behind the fuel tank. Even with the additional weight it flew well. As for your misalignment, I would loosen the bolts holding the fin and try to adjust it. Good luck.

RE: adding weight
 

My Sky Raider with a Super Tiger GS-40 required 2.75 oz of weight on the horizontal. As light as the plane is, if it's balance properly, you probably won't notice the extra weight.

Hogflyer

RE: adding weight
 

Joco, as for your weight, If you are using an APC prop, you can get a wooden prop and probably be able to remove 2 to 3 ounces of weight from the rear. I would recommend using a wooden prop for a beginner anyway. It is cheaper to replace several props than it is to replace that engine. Till you are able to land smoothly, you will probably get a bunch of tip strikes, and a wooden prop will break where an APC prop can bend the crankshaft. If you are determined to use a fiberglass or nylon prop, go with the master airscrew or evo props. They bend a whole lot more and will absorb the shock of a tip strike. I would choose Master Airscrew before Evolution props. It has more flex.

With that engine you should be able to fly well and load the engine right with an 11 X 7 prop.

These guys are telling you straight, to check the Hor. stabalizer for square measure across the fuselage and the firewall, and find center crossways. the distances should be the same from that point to the rear tips of the stabalizer or back tips of the elevator.

To check the wing, find the centerpoint across the tail end of the fuselage and measure to the wing tips from there. Make sure the rudder is not touching in either measurement.

It will probably fly with things crooked but would be more pleasureable to fly if everything is straight.

RE: adding weight
 

well i went to work on the raider tonight and found out i messed the hole up or drilled it wrong as alan0899 suggested or atleast i couldnt get the bolt started for nothing so in order to get it perfectly straight i had to end up carefully putting a wood screw up thru it in its place everything is straight as a string now and im satisified with it but the question now is will this hold or do you guys suggest putting ca or epoxy up along the edge where the wing meets the fuselodge? also i moved the receiver back behind the servos and re ran all my wires the only problem i have now is the pushrods for the rudder and elevator are rubbing on my foam square will this be a problem ? also thanks jrcaster i will try your prop suggestion but hopefully my weight problem will be helped a little since i moved my battery and receiver!

RE: adding weight
 

If I am reading this right, you substituted a wood screw for the 1/4" nylon bolt? the wood screw will rip through the wing as the head is not near as large, and in the case of a rough landing, the nylon bolt is designed to fail rather than damaging the wing, most of the time. Get a 1/4" drill bit and drill out the hole for the wing mount, (wooden block inside the fuselage) and epoxy a piece of a 1/4" dowel rod into the hole. After the epoxy cures, put your wing back on and use the proper drills re-mount the wing. Tap the hole, use thin CA to harden the threads and run the tap through again.

Epoxy or CA where the wing meets the Fuselage? You don't want to permanently mount the wing to the fuselage. If you are trying to build up the wing saddle, peel the covering away gently, CA or epoxy a piece of balsa along the top of the wing saddle, and sand it down to size, then use a covering iron to draw the covering back down.

As far as the pushrods rubbing. If you are using 1/2" foam, you can drop back to 1/4" foam and see if that helps. You don't want anything rubbing.

RE: adding weight
 

G'day Mate,
If you read my post again, I said, the battery in the second Mk1 "was behind the servos" not behind the fuel tank, that is about 3" difference, so you could have saved that weight.

RE: adding weight
 

I'm not familiar with the sky raider, so I don't know the location of the balance point or whether it's marked on the wing. Having said that, you may want to double check the CG location and make sure you're trying balance at the correct point.

DaveB

RE: adding weight
 

on this model its not nylon bolts its 2 machine head screws the holes were misaligned it looked to me like so thats why i decided to put the wood screw in

RE: adding weight
 

If it has the same size head you should be ok. If you cut new threads in the wing mounting block, use thin CA, a drop or two and let cure before you put the wood screw back in.

I forgot that a few manufacturers use steel screws to mount the wing instead of nylon bolts. Usually on a trainer the wing is rubber banded down.

How is your tail-weight situation going? The only things I can think of to reduce your weight are, lighter prop, mounting your engine as far back as you can, smaller spinner, or moving your gear toward the back of the plane.

RE: adding weight
 

im in the process of moving everything back behind the servos i think this is gonna make a big difference i still think i will switch my prop to a wooden one also..........

RE: adding weight
 

Let us know how things turn out.

RE: adding weight
 

Joco1,

The Evolution 52 weighs 14.5 oz w/o muffler.
The OS 46 LA weighs 9.6 oz w/o muffler.
Youve got a lot of engine in front of that plane which explains some of the need for the weight.
I fly a Mach II with an OS 40 LA with no trouble.

That being said I did notice on one of my Mach IIs I had to put some front weight on.
Since everything else was the same I can only guess it was due to wood differences.
Usually this plane balances right on.

Good Luck,
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