Thursday, February 15, 2007
F-463 completed
These brackets have been enormously time consuming. The problem is VANS plan is close to an irrelavancy, as I explained before. This is compounded by the practicality of the task. Do you drill from the inside to the outside, or vice versa? From the inside it is physically quite difficult. From the outside, the wing is in the way. Perhaps if I had an even smaller right angle drill.....Finally though, they are just about complete. I say just about because, although I remembered to allow room for a fat rubber washer in front of the bracket, on the outside, where the fuel will enter the fuselage from the flop tube, I did not allow for it in the spacer on the inside.
Ideally, I will not bring the fuel into the fuselage at that point, but take it under the -463 and enter under the step. I am just not sure the pipe will bend that tight. We will see....
Sunday, February 11, 2007
F-463 tank brackets continued..
Finally the RHS F-463 is complete. It bears only a passing resemblance to those shown in the RV4 plan and a lot more to the RV9A plan which I was fortunate to have to hand. Here is the finished installation.
The problem is that the glass fairing sweeps in very close to the bottom bolt in this picture.
(I may yet have to grind a small amount of glass away.) If the bracket continued down so that it was bolted to the bottom longeron the fairing just could not fit on.
My solution - and I think most -4 builders - has been to put a vertical inside the fuselage to which the bracket can bolt. Here is a picture.
The external bracket uses the upper two bolts. The other two holes are just to save a few grams.
I have also possibly installed the platenut bolt assembly that joins the wing to the fuse the reverse way around, but the plans are inconsistent on this point. For various reasons it made more sense to me done this way.
Here is the fairing slid almost into place to show the problem.
The problem is that the glass fairing sweeps in very close to the bottom bolt in this picture.
(I may yet have to grind a small amount of glass away.) If the bracket continued down so that it was bolted to the bottom longeron the fairing just could not fit on.
My solution - and I think most -4 builders - has been to put a vertical inside the fuselage to which the bracket can bolt. Here is a picture.
The external bracket uses the upper two bolts. The other two holes are just to save a few grams.I have also possibly installed the platenut bolt assembly that joins the wing to the fuse the reverse way around, but the plans are inconsistent on this point. For various reasons it made more sense to me done this way.
Here is the fairing slid almost into place to show the problem.
Monday, February 05, 2007
Control System
The control system in the centre fuselage is almost complete. The points to note are:1) Earlier on this blog - see Jan 12th '07 & July 8th '06 entry - I considered making the F-449 bracket so that it moved the stick further forward. In the end I have used the bracket as defined by the plans, but added a 1/8" shim between the bracket and the tie bar. This has moved the aileron pushrod tubes forward so they are almost central fore and aft, with respect to the pushrod tube hole in the sidewall. Making a firm decision regarding this, enabled me to match drill the 4 bolt holes for the rear mounting point of the stick assembly, in the centre of the picture.
2) I still have to increase the clearance of the push rod tube as it exits through the side skin. It is not blocking full movement as the rod gets to the limit of its travel but it is just touching. You can see this in the picture. With the stick fully over to the left the RH push rod tube just touches at the top of the exit hole. If I relieve this by 1/16th to 1/8th, that will cease. It is the same on the left side.
3) I have had to grind quite a bit away from the hole above the rear spar, to ensure it does not touch, as you move the stick from side to side. I have an extra heavy bracket here to permit a 5th point for the PAX harness. I may need to grind a bit more off yet, to be sure it does not touch.The flap mechanism went together quite easily, though the stressful bit lies just ahead; cutting holes in the exterior skins for the flap push rods.
Here is another picture of the fuse centre section.
Postscript - 12 May 07
For completeness I have added a picture of the manual aileron trim unit.The way it works (I think) is so.
The stick runs through the centre of the UHM block. The RHS long screw serves both to clamp the unit to the stick, as a pivot for the trim arm (green) and to provide some friction in the system. The LHS screw increases the friction in the trim arm. The springs attach to the lower part of the trim arm and the other ends to the sides of the compartment in which the stick is located. I presume some locking wire is used to adjust the length / tension.
So if you move the top of the trim arm to the left, the left spring tightens and the stick is offset left.
(If you click on the picture you can get a bigger one, which will enable you to see more detail.)
Thursday, February 01, 2007
F-463 Tank Brackets - read this before you make yours!
One day this week when I was putting off the day when I had to drill the rear spar, I decided to cut out the brackets that attach the fuel tank to the fuse. I diligently marked out two, according to the plans, and worked away with my hacksaw. (Yes, I still haven't bought a band saw..its a hacksaw and file for me!)When I had one roughed out almost to size I offered it up against the side of the fuse. It bears little relationship to what is needed.
I quickly reworked the other one to see if I had already gone too far to salvage it. The answer is probably 'yes' but it illustrates how wrong the plan is.
The bracket on the right is to plan, and bears no relationship to the relative positions of where the bolt holes need to go. The one on the left is to my design, but will probably have to be remade since it might be marginally short.
I am also advised that you need to take great care that they do not displace the wing fairing. Interestingly, in different places in the plans they are shown bolted to both the back and front of the 'ear' coming from the tank. The logical way, and I think VANS intent, is that they sit behind the 'ear'. If you have a flop tube it is probably essential in view of where the fuel exits the tank.
Labels: tanks wings
