[Tango Mike]

I bought my '97 RV-4 in 2000 from the builder, a self-described speed freak, who told me he had included a number of options to reduce drag: cowls, a hard engine baffle, wing-root fairings, wingtips, fast-back canopy mod, and rudder cables routed within the fuselage and not exposed to the slipstream. He won an award at Oshkosh '97, apparently, and referred to the airplane as an RV-4.5.

A friend with a long-term -4 project asked me if the records included any information about the source of the optional parts. He also asked whether I knew if the oil-cooler arrangement on the airplane was builder-custom or an option offered by someone else.

The records are no help and I have no current contact information for the builder, so I've included some photos of the options to ask if anyone in the Van's community might be able to shed some light on their source. Any ideas would be appreciated.

The oil cooler (sorry for the focus):


The engine baffle (view 1):


The engine baffle (view 2):


The engine cowls:


Tosh

 

[Kahuna]

I don't recognize the oil cooler arrangement. Wold not be hard to make that. Ill tell you this, I would have lost the bet that it would have survived the vibration hanging that far off the rear baffle hard mounted to it. Its a pretty nice setup. What is the hinge mechanism on exit? Little flapper door?

 

[Tango Mike]

The hinged door allows adjustment of the amount of air passing through the cooler. I've never had to use it in Texas and the Southwest, but the cooling on this airplane is so efficient that it would be a nice feature if I were living in a colder climate.

 

[AX-O]

The engine plenum looks like it is a modified sam james plenum for a 360 engine. Those intake holes are huge.

The cowling looks to be a modified vans cowling.

I also can't belive that oil cooler set up has not failed. Or any damage on the baffles. how many hours on your bird?

 

[David Paule]

I think the closest current commercial option would be the Sam James cowl and plenum, which appear to have smaller openings than yours.

http://www.jamesaircraft.com/RV-4.html

The RV-4 FWF is similar to the RV-3B, and this is the first plenum I've seen for that shape cowling. Interesting.

These two airplanes, I think, have relatively good cooling compared to some of the other RVs. I don't know why.

Dave

 

[Tango Mike]

The plenum and oil cooler setup

The airplane has a little under 600 hrs total time, with the same SMOH on the O-360-A1A. I've owned it since 2000, and there are no signs of stress fractures anywhere on the oil-cooler assembly, which is fabricated of some relatively thick aluminum.

I've read/been told that reducing cooling-air drag is one of the most effective ways to increase cooling efficiency and reduce total drag, which this builder considered to be an enemy worthy of a tactical nuke. The large air intake holes, plenum, and the rolled edge at the bottom of the firewall all contribute to unobstructed airflow and help make this the quickest RV I've ever flown. Lightweight helps as well, of course, and it's about as basic a VFR airplane as you can get, with minimum upholstery and few extras.

Thanks for the lead on the source of the plenum.

Tosh

 

[Tango Mike]

Love the details on your fastback, Axel. Here's a photo of mine, built by William Davis in 1997. The mod completely changes the look of the airplane. Do you have any idea how many of them are out there?

Tosh

[/URL][/IMG]

 

[AX-O]

Wow, nice looking plane. I don't know how many are out there but i think there has been a surge in recent years for the fastbacks. I have helped about 12 people that are building new fastbacks. And a few more that modified their flying -4s.