On such a very low drag airframe, that lot must surely contribute a significant amount of the total drag. Take a look at http://www.cfiamerica.com/id4world.html and you'll see some really dangly tailwheels there.

The simple solution is to slide a short length of locking wire through the small triangular bump-stop immediately under the rubber ball, and pull each end up tight to the steering arm holes. Wind them around, and your tailwheel won't dangle any more. Peter Goldin even had a neat fairing around his. I've been experimenting with a foam fairing formed in the top of a one litre (quart) Coke bottle, but I get so much oil there from my extended breather tube, I don't think it would last very long. Those of you who don't fly a lot of aerobatics might find it feasible to make a fairing.

As you can see here, tying up the wheel significantly reduces its drag.
Note the tiny wheel, necessary to keep my long propeller off the ground if the main tire punctures.
Note, too the squashy and worn rubber bumper, mostly the result of oil spewed from my earlier, shorter breather tube, but this also helps with prop clearance.
Also note the new exit of my long breather tube extension.

It's also dead simple to fair the outrigger legs, although these fairings need to be flexible. I cut triangular lengths of ordinary furniture foam with an electric carving knife, hollowed them out a little, and glued them on to the backs of my outriggers, then taped them into place for security.

There are several types of wheel carrier on the outriggers, but mine now have less drag than any of the originals. I bought one foot of thick-wall stainless steel tubing with a one-inch ID (but check your outriggers' OD first). Cut a four or five inch length, cut a couple of slots in the ends, and fitted roller-blade wheels. These have sealed ball-bearings. Mine drag through the sand at our airfield, and have lasted two years so far.

No, I haven't measured my cruise speed increase, but I must have reduced my little airplane's drag quite a lot. I'll try and get some photos.

Yours, Bob

[Edit by Bob Grimstead on Saturday, October 27, 2007 @ 02:12 AM]

I did some crude fairings on my RF 4 similar to yours, Bob. I shaped a rear and frontal foam fairing of styrofoam and simply taped it around the outrigger legs. I was quite pleased to find cruise speed increased from 100 to 105-110 mph (Rectimo 1400cc).

BUT after 5 hours one of the outriggers snapped at the insert in the wing- I had concentrated the stresses to much so the outrigger flexed almost exclusively at this point. Luckily, I found the outrigger (it hadn´t bumped anyone´s head either) and my next attempt will include a heat-moulded polycarbonate fairing that allows the ourigger to flex at its hole length. I agree your design seems simpler but I am just a sucker for proper aerofoils and hangglider uprights (which are beautifully faired) are exactly the correct dimensions to hide a Fournier outrigger, so the mould is ready. And for some reason I happen to have a large collection of deceased hangglider uprights in my shop...

Just 4´fun/ Jörgen, SE-XST

I used white electrical tape, wound around the frontal and rear fairing + the strut. I don´t think that was the main problem though. I also glued the styrofoam fairings to the strut. Styrofoam is pretty stiff in compression and I think that this non compressible frontal and rear fairing acted like a brace and just didn´t leave enough "play" for the strut. My stupid mistake, I´m afraid.

If you use compressible foamfairings as Bob suggests you probably won´t have any problems. I don´t know about glueing them on to the strut though, maybe it´s better to fit mylar tape or similar to facilitate sliding.

By the way, I haven´t gotten round to make my next version of fairings yet. As some Governor somewhere used to remark: "-I´ll be BAKK".

Just 4 fun, take 5(b)/ Jörgen SE-XST

[Edit by Jorgen on Tuesday, August 21, 2007 @ 03:58 PM]

[Edit by Jorgen on Tuesday, August 21, 2007 @ 04:08 PM]

Sorry for the slow reply. I'm busy building a hangar here in Britain. Forty feet by forty feet to take our Champ. but... a little RF4 would fit in there nicely too. Now if only I can find one....

That tape? It was a very special, high-tech PVC tape -- called 'duct tape' I seem to remember.

Silver PVC tape (electrical insulation tape) works well, because it stretches when you put it on, especially on a hot day, so you can form a fairly tight shape with no wrinkles. I had to do mine a couple of times to get them neat. Cost maybe $2.

On one of my early attempts I didn't seal the edges well and the tape started unpeeling, but the foam didn't fall off. If it had, it weighs nothing, so would do no damage to earthlings. Just make sure your name's not on it anywhere.

That furniture foam for the fairings was OK, but not really dense enough to hold its shape properly, so now I'm using a denser white foam, cut from a kid's swimming aid float. Seems to work well, and certainly flexes OK. You should have seen those outriggers bend when I landed with the wheel up (see photos on the site, somewhere) but the foam and tape didn't come off.

I would be very interested to hear about Jorgen's eventual result. That seems like it will have less drag for little if any more weight -- always our goal.

Yours, Bob

[Edit by Bob Grimstead on Tuesday, November 18, 2008 @ 00:43 AM]

We just bought this other RF4 and it has this neat drag-reducing mod: a spring to hold up the tailwheel. I thought I'd share it with you all.

Yours, Bob

[Edit by Bob Grimstead on Tuesday, November 18, 2008 @ 00:22 AM]