Painted/unpainted

[peter anson]

Here's a surprising (to me anyway) addition to the paint or polish argument. It appears that B17s were actually faster when they were painted than left unpainted, supposedly the result of paint filling in little gaps on the surface and also smoothing the surface of the flush rivets. https://www.youtube.com/watch?v=420fO_-u0nE The extra fuel they needed to carry to keep up with their painted brethren far exceeded the weight saving of leaving them unpainted.

Peter

[GraemeSmith]

Interesting.

I've also read that the RAF night heavy bombers were found to be 6-8mph slower as their paint weathered compared to newly painted planes. Keeping them washed was also considered important.

THAT SAID - if an RAF heavy bomber survived long enough for its paint to be weathered then it was as likely to be "war weary", dented, a bit out of rig and running on older tired engines. Which might have been the real reason the plane was slower.

In our case - where our usable load is so low - I'm more inclined to stay with unpainted to keep the usable load up.

What might be interesting is the difference between unpainted, painted and vinyl wrapped. Anyone know the weight of a wrap job? If it is less than paint and still bridges the seams and smooths the rivets - it might be the sweet spot.

[Area 51%]

I had a 1961 172 that had sat through more than one hailstorm and had "golf ball" dimples on all the upper surfaces. It would outrun any other similar 172 with smooth wings.

Some years ago, someone was experimenting with "golf ball dimple" tape used at the thick portion of wings, propeller, and struts with a reported decrease in prop noise and significant speed increases. I'm thinking my Cessna was taking advantage of that phenomenon.

[Scott Todd]

It wasn't really asked here but I thought I would post for future readers since it fits the thread title. I just couldn't afford the ridiculous price for a paint job I was hearing from other builders at my airport. I decided to paint it myself as I REALLY didn't want to polish it and I've been using a similar paint scheme on R/C models lately. Here is a photo and a description a few posts down of what and how I painted it.

viewtopic.php?f=5&t=6028

I used about 1.5 quarts of primer, 2 quarts of white, and about 1/2 of red. I would estimate less than 10 pounds total. I think its totally worth it in the end. My finished weight is 620 which includes radio, transponder, ADS-B, Custom individual hydraulic brakes, Odyssey 680 battery and baggage sack. I was quite pleased with this. I spent less than $500 on my sample paint, finish paint, prep materials, two harbor freight guns, Amazon Vinyl, and cleaning supplies. Its not a show quality paint job but looks great on a walk around. I would encourage anyone on the fence to consider painting themselves. Its a lot of satisfaction.

[peter anson]

One of the people at my home airfield did a weight and balance before and after painting his Victa Airtourer (about the size of an RV10) with primer and two top coats. Weight difference was less than 8 kg (17.6 pounds).

Peter

[peter anson]

Just watched Graeme Smith's excellent video on testing vortex generators on the wings of his Sonex. I reckon he's the guy to do a do a before and after test of the effect of golf ball dimpling on his Sonex ;-)

Peter

[GraemeSmith]

Glider pilots use "Turbulator Tape" to get "golf ball" effects on their wings.

If I ride out many more hail storms in the tie downs - I won't need to spend the money on the tape...... :-)

[Murray Parr]

I have been wondering the weight of the vinyl wrap I used (Viviid Premium Gloss Lamborghini Orange) on my waiex B model. I have come up with a fairly accurate weight per square meter after I removed the wrap from underneath the floor skin and weighed it.

Area removed 1175mm x 1012mm weighed at 214 grams which = 179.97 grams per square meter. I read on another post that 27 square meters is about the square meter coverage for a Sonex.

If my waiex is 27 square meters then the total weight of the 4.86kg or round up to 5 Kg (11 lbs)

[XenosN42]

The metric system rules!

[Bryan Cotton]

5kg would be as much of a killer for me as 11 lbs!