I am attaching the wings to the fuselage for the first time. Just read up the relevant section of the construction manual.
Are there any specific issues to watch out for ? Thanks for any heads up on this.
By the way, I am doing one wing first, removing it and then doing the next - due to shortage of room in the garage. That means I will not be able to attach both wings together and take a look if both sides look symmetrical in rigging angle / dihedral. Is there a problem in doing it that way ?
Also I found the tires can get compressed a little during the whole process. To avoid that I am thinking of removing the wheels and keeping a wooden block under the axle on both sides, of roughly same height as a loaded wheel. I hope it works out OK.
I would leave wheels on. I added wood blocks under wheel axel just inside the LG legs. Also that may work fine. Just do not take all the weight off the wing once bolted in place. The fuselage is not designed to take the loads that way and will twist possibly even break. Your moving along well. B-
Brian, Thanks for your suggestions. Yes I agree the wing's weight cannot be taken by just the two wing-to-fuselage mount points. The struts need to be in place to support the wing. I forgot to mention, my plan is to attach the wing first, keep it supported with an adjustable stand near rib # 7 just outside the strut mounting location. After bolting the spar brackets to station 2 and 4, immediately make adjustments to the dihedral and wash-out per plans, and in the same process, attach the struts too. I feel it is better to do both actions in one go. That is just my plan, let us see how it turns out.
Aeronut, yes it is good to have adequate help to make it easier.
The requirement for initial wing to fuse attachment is I guess slightly different, because we need to hold the wing in place, and be able to move it in and out of the fuselage side till we get the holes drilled on the fuse sides.
Also we need to be able to raise the wing tip or lower it to adjust dihedral, then lower the rear of the wing independently from the front to adjust wash out etc.
I made a temporary jig fitted to the garage side 2x4 studs with adjustable elevation setting by using clamps. Raise the entire wing tip (by raising front and rear clamps together) and you increase dihedral. Raise or lower only the rear wing tip by adjusting rear clamp , and you adjust wash out etc. ( Minimax has zero wash out, but still we need to bring it to zero if it is not, and for this to be able to adjust the front and rear clamps independently helps. )
I did this mainly because I did not have the luxury of some family member standing and holding the wing up all along the attachment and strut alignment process. I am able to do it all alone with NO help.
I already attached the left wing yesterday. Now I will attach the struts to the left side.
I have attached the left wing to the fuselage. The joint at wing root is pretty snug with no play at the wing root. However because the struts are not yet connected, I found the wing tip has slight fore and aft freedom of movement of about 3/4 inch. This is negligible and once the struts are connected, even this fore and aft play at the tip will disappear.
But the question I have is : If there is even a small amount of free movement at wing tip, what would be the ideal position to keep before struts are connected ? I realize this play is very tiny and it may not matter, but I just want to make sure I am not missing something.
You want the wing to be perpendicular to the longitudinal axis. Measure the sides of the triangle formed by the wing, the fuselage centerline and the diagonal from the wing tip to the fuselage centerline at the tail then use Pythagoras. It doesn't have to be perfect more of a check on how straight your wing and fuselage are.
While attaching the wing to fuselage, how does one measure the dihedral so that it comes out exactly 3 degrees ? I didn't see it in the construction manual either. One method would be to just keep the root rib's plywood parallel to the fuselage side wall. But if the root rib had any error in measuring 3 degrees, that error will creep into the wing dihedral as well. Any thoughts on this ? Thanks.
The end of the strut which attaches to the wing pickup is telescoped into the outer strut. So you support the wing with a trestle of some sort when pinning the root fixings, just getting it somewhere near right by eye. Then you either use an adjustable level gauge (made in 2 parts that gives a digital readout on the included angle), or a conventional level with an adjustable square set to 3º (or 93º or 87º), or measure the length of your level gauge & calculate the thickness of shims to place under one end to equal 3º.
However you do it, you measure against a spar cap with a level to get the dihedral. When you have the wing supported at the correct angle, then you drill through the strut end. With the inner strut tube attached to the wing pickup fitting, drill a 1/8" dia hole through the telescoping sections, and put in a temporary pin. Bolt the strut to the wing, remove the trestle, & check the dihedral again. If it's wrong, you can adjust it on the telescoping sleeve, & drill out your small hole to a larger size.
As long as you set the root rib close to 3º, any gap at the top or bottom where it butts against the fuselage will only be very small. The strut length sets the dihedral, not the root rib.
Note that it is best to do both wings simultaneously, so that the fuselage doesn't lean over & give a false reading. If you only have room to do one wing at a time, make sure the fuse is kept completely level by some other means. Check for this using a level across the cockpit upper sides.
I'm pretty sure this procedure is detailed somewhere in the plans or building notes.
A "Smart Level" ( it is the trade name) is an electronic level that can be set to read in degrees is a very handy tool for this operation. They are sold at many places that sell tools and run on a battery or perhaps you could barrow one. They are accurate and I found that I have used it a lot on other projects around the home.
Aeronut, Thanks. I think I will buy one of those before I attach the next wing on the other side. Anyways I did the next best thing, for this wing, and used a 24 inch carpenter's level. For 3 degrees slope, the level should be raised at one edge by 1.25 inches. Its is a little more cumbersome but I managed to somehow do for this wing. ( Tan 3 degrees = 0.0524; so over a 24 inch length of spar it must rise by 24 x 0.0524 = 1.257 inches )
Some of the questions I ask could seem elementary for the experienced builders. But the point is this is my first build, and also I have never seen anyone building from up close. My only exposure to home building has been visiting Oshkosh Airventure once.
I would check the wing that is already done against the smart level just to be sure if you're planning on doing the other side with it. Otherwise, I would use the same tool for both wings.
Easy and very Accurate way is to use water filled tubing as a level full length of the wing and measure the extra height at the tip , I use 3.5 inches for a HiMax and 7 inches for a Minimax although exact measurement is 7.285" , and you don't have to buy anything extra because the 1/4" tubing you will need and reuse for the static and pitot pressure anyway.
Note that it is best to do both wings simultaneously, so that the fuselage doesn't lean over & give a false reading. If you only have room to do one wing at a time, make sure the fuse is kept completely level by some other means. Check for this using a level across the cockpit upper sides.
I'm pretty sure this procedure is detailed somewhere in the plans or building notes. Bruce
Bruce, you brought out some very useful points in your detailed reply. Thanks.
My question was about how to measure the angle itself. Because the the manual mentions in details about how to set washout to zero. It was not very specific on how to measure 3 degrees or what tool to use.
About the other topic you touched on, I did support the wing on a jig of some sort while doing all of this. Regarding sequence of drilling and assembly, first I drilled and assembled the axle end assembly of the front strut , then after getting the alignments about right, I drilled and assembled and bolted the 3 tube assembly in place, at the outer end of the front strut.
But the last hole on the inner tube RS 405 where the strut attaches to the wing, I drilled last. because it was easier to make final adjustments at one point than on two points. But I suspect your method of using the telescoping tubes to make adjustments is more desirable. ( I made sure while making initial alignments that I had a little excess length of the last tube RS405, so that I would not run the risk of having too little clearance from the tube's end while drilling the last hole )
And the other point you mentioned is also spot on. If you are doing one wing at a time like I did, while you are doing all of this, the cockpit tends to lift at the outer end ( wingless end ). I discovered this in time, and placed a heavy object ( a used motor cycle battery) on the outer end of the axle towards the wingless side, to keep cockpit level.
I would check the wing that is already done against the smart level just to be sure if you're planning on doing the other side with it. Otherwise, I would use the same tool for both wings.
Easy and very Accurate way is to use water filled tubing as a level full length of the wing and measure the extra height at the tip , I use 3.5 inches for a HiMax and 7 inches for a Minimax although exact measurement is 7.285" , and you don't have to buy anything extra because the 1/4" tubing you will need and reuse for the static and pitot pressure anyway.
Logged
