Evolution of the nose wheel sub-fairing

[Bob Axsom]

I was surprised by the speed gain when I added a sub-fairing to the nose gear - the speed went up to 184.4 kts. The sub-fairing is two piece (fore & aft) with the forward part having a flange that extends over rear part by ~1/4". I had a aluminum clamp strip riveted to both sides of the the forward part so that they went inside the aft part. Thus the flange and clamp strip forced a tight closure of the gap between the two halfs.

After the 2008 Airventure Cup I made a rough short approach at Jefferson City, MO and caught one of the clamp strips with the nose tire sidewall. I removed the strips and refinished the sub-fairings and have flown with a small trailing gap which I thought would not be significant. Well I have been flying around 182 kts since then. It dawned on me that the small trailing gap may be a problem. I'm going to add some fiberglass extensions that will allow me to add a piece of aluminum inside the aft part of the sub-fairing on both sides and tap them for #8 screws. This will allow me to pull the gaps closed and see if that speed comes back.

Bob Axsom

[mtnflyer]

Bob,,,, any chance for photos.....thanks, Dave

[Bob Axsom]

They are in a thread with this title:

Subfairing for Oldstyle RV-6A Nosegear

Bob Axsom

[Lycosaurus]

Originally Posted by Bob Axsom

They are in a thread with this title:

Subfairing for Oldstyle RV-6A Nosegear

Bob Axsom

Thread link http://www.vansairforce.com/communit...RV-6A+Nosegear

[Bob Axsom]

The three layer fiberglass tabs have been added at the lower rear end of the fwd part of the subfairing. They have been shaped and sanded to a smooth low profile extension over the aft part of the subfairing. Small plates have been made from 0.090" 2024T3 aluminum, tapped for 8-32 screws, filed to a smooth tapered edge all around and double flush riveted inside the aft part of the subfairing. I decided to use dimpled washers with flat head stainless steel screws to fasten the fwd and aft parts of the subfairing together near the bottom but on the side. There is a concern that the tire may come in contact with the custom tapped plates and that is the reason for the smoothing and rounding of the edges. The screws will be very short and will not extend beyond the innermost surface of the tapped fastener plates. There is no room for plate nuts which would have been the easy solution. Since the tapped plate fasteners have no mechanical locking device I will have to use non-permanent loctite upon installation of the screws. After the installations were complete I drilled out the mounting holes in the new tabs of the overlaying fwd part of the subfairing to 3/8" for the dimpled washers. Unfortunately, one of then caught and ripped out at one edge. I have added three more layers of fiberglass to the tabs and I am monitoring and working with them through the 24 hour cure cycle. When they are semi-hard I will cut the holes with an xacto knife and avoid the drill snag risk.

As I worked through this modification it became apparent that when the two attach points are fully implemented I do not need the overlapped fwd and aft part of the subfairing tabs at the top of the assembly. I removed the tab at this location on the forward part. This is a definite improvement though small.

Bob Axsom

[Bob Axsom]

I just cut the 3/8" holes and trimmed the excess material. All that's left is a little sanding, trial assembly and paint after the epoxy cures.

Bob Axsom

[Bob Axsom]

Trial install OK ready to paint

Bob Axsom

[RobinHou]

Bob, have you try the same sub-fairing concept on main wheel pants, and the result? If not, why not?

[Bob Axsom]

The results are in this forum somewhere I think if you search under subfairings you will find the photos and test results. They are the newer design pressure recovery eggs and there was no measurably improvement. My nose gear fairing is the older flat sided fairing and the difference with the subfairing was remarkable.

Bob Axsom

Try this:

http://www.vansairforce.com/communit...&highlight=MLG

[RobinHou]

Originally Posted by Bob Axsom

The results are in this forum somewhere I think if you search under subfairings you will find the photos and test results. They are the newer design pressure recovery eggs and there was no measurably improvement. My nose gear fairing is the older flat sided fairing and the difference with the subfairing was remarkable.

Bob Axsom

Try this:

http://www.vansairforce.com/communit...&highlight=MLG

Thank you, Bob. Good read. Robin