Aligning the wheel fairings

Steve Sampson · #1 10-09-2006, 01:26 PM

I have never seen it done this way, (but I am sure I am not the first), I wondered if by placing the engine mount in the horizontal plane, resulting in the wheel fairings needing to be alaigned in the vertical plane, it would make the job easier? If that is not clear take a look here.

If anyone has experience of doing it this way I would be very interested in any advice/ gotchas/ etc. Would you do the same again?

Thanks,

svanarts · #2 10-09-2006, 02:36 PM

That's a very interesting way to do it. I can't think of why it would be any worse than the traditional way. I'm sure others will speak up here.

BTW, my family came over as pilgrims, not colonists.

pierre smith · #3 10-09-2006, 04:05 PM

On my 6A, the firewall doesn't appear to be perpendicular to the upper longeron at the cabin-the place where the airplane is levelled.

Secondly, the engine is offset to the right, so your wheelpants may not be parallel to the airplane's centerline, which they should be.

Thirdly, why would you want to do it this way in the first place? You have little or no reference to the airplane's centerline compared to a finished fuselage in a levelled condition.

Regards,

hevansrv7a · #4 10-09-2006, 04:08 PM

1.OK, it's a -4, not a -9A, sorry - I never did read well.
2. Doesn't the alignment depend to some extent on the wheels actually supporting the airplane weight? Are you sure the firewall is supposed to be perfectly vertical?

L.Adamson · #5 10-09-2006, 04:15 PM

Quote:

Originally Posted by hevansrv7a

2. Doesn't the alignment depend to some extent on the wheels actually supporting the airplane weight? Are you sure the firewall is supposed to be perfectly vertical?

Technically, the alignment is suppose to be with weight off the landing gear, as in flight. Of course this means jacking up the plane, lines scribed on the floor, etc. I'm just not sure how many do it the weight off the wheels way.

Mel · #6 10-09-2006, 04:34 PM

Due to the nature of the Whittman landing as used on the RV taildragger, when the weight of the airplane is on the gear, the gear splays out causing a slight amount of toe-out. If you align the wheel pants with the airplane sitting on the gear, they will be splayed (toed-in) in flight. The wheel pants and gear leg fairings must be aligned with the gear unloaded for proper inflight alignment.

hevansrv7a · #7 10-09-2006, 05:52 PM

Quote:

Originally Posted by Mel

Due to the nature of the Whittman landing as used on the RV taildragger, when the weight of the airplane is on the gear, the gear splays out causing a slight amount of toe-out. If you align the wheel pants with the airplane sitting on the gear, they will be splayed (toed-in) in flight. The wheel pants and gear leg fairings must be aligned with the gear unloaded for proper inflight alignment.

I have not done mine yet. Good to know! Thanks.

fodrv7 · #8 10-09-2006, 06:49 PM

It is not difficult to do it as per the plans and it will be much more accurate. The accuracy of doing it on the bench is dependent on having the engine mount horizontal and that in turn is dependent on the dimension of the engine mount which is around 40?
Aligning it based on the fuselage gives you over 15? do establish a baseline.
Here?s how I did it.
1. Three adjustable car stands, two under the wing and one under the tail, make it a cinch to level the fuse laterally and longitudinally. See PIC ONE.
2. A cheap laser level (The type that project a vertical and a horizontal line) sat on the floor under the rear fuse can be aligned with the centre line rivets and projected onto the floor. Use a brickies chalk line to mark the centre line on the floor. See PIC TWO
3. Measure from the Centre line to the front and rear of the Fairing and project the centre line vertically to the front and rear of the spat. Se Pic THREE
But, the nasty bit is doing the leg fairings. See PIC FOUR for a brilliantly simple solution I came up with after about 30hrs of frustration.
More info available by Email.
Pete.

Steve Sampson · #9 10-10-2006, 11:40 AM

Thanks for all the replies even if most didnt think it was such a good idea. It has made me have a good think about what I am doing. Having done it the way VANS suggest once, I think, so far, that this is much better.

In response to the negatives:

- With a digital level it is easy to find out if the firewall is square to the reference level. On mine it is, but it would be easy to allow for.

- Yes the engine is offset, but that is all built into the engine frame. If you ensure the base of the frame is level that is not an issue.

- Having the wheels in the air is an advantage because I want the alignement for flying......not taxiing :-)

- I think the digital level plus plumb bob gives me a high degree of accuracy. The hard part of the alignement will be aligning the spats to the plumb bob.

- The huge advantage so far, is being easily able to see what needs to be cut away to accomodate the tyre, and sit on a chair while I do it. Also, set up is easy.

I will let you know how I get on and if I think this continues to be a good idea. I am not sure I will be able to continue to do the gear leg fairings this way which reduces its advantage. I will have to think about that.

Thanks again,

DanH · #10 10-10-2006, 12:32 PM

If I recall correctly, the Rocket guys align and install their gear leg and axle assemblies (which are not the same as a RV) using the engine-mount-on-the-table method you describe in your first post. If it is accurate enough for axle alignment, it is likely accurate enough for pant alignment.

Dan