Stabilizer Strut Fairings

[jiott]

I just finished installing fairings over my horizontal stabilizer struts. I ordered plastic fairing material from Quad City Aircraft, 5' of their smallest size. It is sized for going over 1/2" round tubing, but it works over the 5/8" tubing on the horizontal stab. It is very light but also sturdy. I'm not sure but I believe it is ABS plastic, similar to the Kitfox lift strut fairing material. I scuff sanded it with 220 grit and it took paint quite well.

It is quite a tight fit over the 5/8" struts and I couldn't slip it on by hand, even after greasing the strut. I finally had success by using 6 rubber faced trigger type bar clamps spaced along the fairing and positioned to squeeze the fairing more open. It then slid on with minimal effort. It was easy to properly position the fairing in the airstream with the clamps on. After removing the clamps, the fairing grips the strut very tightly and I decided that no glue was needed to keep it in proper position.

Time for a flight test! After about 1 hour of straight and level testing at 2000' and 5200 rpm (my normal cruise setting), I was able to measure the following results compared to previous testing without the fairings: The fairings gave me a solid 2 mph (maybe even 2.5) speed improvement, and a 0.1 gph reduction in fuel consumption-measured by my fuel flow meter. I believe these results are reasonably accurate and done with as much "apples-to-apples" comparison as I could, but of course I am no Chuck Yeager test pilot. Well worth the effort and cost ($35 + paint) in my opinion. Pictures below.

[jrevens]

That looks real nice, Jim!

[500helicrazy]

I'm going to try this as well! I need some for the lift struts too. Thanks for sharing!

[efwd]

Those look great Jim. I'm in also. Thanks for the lead.
Eddie

[jiott]

Engineers always have to put numbers to things so I did a little simple math and the improvements I reported amount to $0.71 for a 100 mile trip, or roughly $0.71 savings per hour of cruise flight at 5200 rpm and $4.00 per gallon clear Mogas. This is more than I expected. Imagine what the dollar savings are for the lift strut fairings, which most people claim to be about 10 mph improvement!

[Esser]

Hey Jim. I’m looking on their website and their small seems to be for up to 1.25 tubing. I can’t seem to find the even smaller stuff you have.

[jiott]

Its there, but easier to just call and ask.

[jiott]

After several more days of flying with the new stab strut fairings, I will back off slightly on my claim of a good solid 2 mph increase and settle in on a solid 1.5 mph increase and some fuel consumption decrease but hard to measure. Still very worth doing for such a low cost, light weight and easy, plus it looks kind of cool. I might tackle the jury struts next, but I'm still looking for something smaller than the ideas presented so far on this forum. I may use triangular shaped balsa (sold at RC stores for aileron material) shape it to be glued on to the backside of the struts, and the wrap the whole thing in tough leading edge tape.

[Esser]

Lowell put mine in the mail. I’ll let you know how it goes although, I will have no before and after comparison. And it might be s couple months to get data even then :p

[Esser]

Speak of the devil and he shall appear. I just received my jury strut fairing Lowell did an amazing job. They are incredibly nice and are extremely light weight. I think this is a no brainer mod.

[AirFox]

Have any pictures Josh?

[Esser]

I’ll take some this morning. I’m having a hard time posting pictures that are big enough to see detail ever since photo bucket went down. I’ll see what I can do.

[Esser]

Hopefully you can see enough detail. I just weighed them. 1.1oz each or 33g

[AirFox]

Thanks Josh! Now I want some. Why do you have so many?

[Esser]

Ah sorry, It must be confusing because this is in the stabilizer strut fair thread but these are for the jury struts. The front, back, and diagonal. X2 for a total of 6.

Quite a bit will be trimmed off so they will be lighter yet, but then add paint and hysol. I bet total installed weight will be less than 8oz total

[jiott]

Looks nice. What is the chord length overall front to back?

[DesertFox4]

15014


My horizontal struts with glass fairings installed, primed, sanded and ready for paint.

15015

Horizontal stabilizer struts and jury struts faired. Jury struts not yet final sanding completed. All fairings were two layers of very lite hand layed up glass. Came out great. The yellow sprayed on primer is for filling pin holes.

[muth]

Fairings made the old fashion way, light abachi wood was shaped and covered with glass.

[efwd]

I sure wish I understood how it is you can lay up fiberglass and have the surface come out smooth instead of the way it is on the inside of the engine cowl for example. I thought my sweet job on the balsa wood flapperon tips were smooth and sealed good. Still can see some wood grain. I was proud of how they turned out until paint was applied. Still fine, but not great. Next time Ill buy them from KF. It was still fun making them.
Eddie

[David47]

Very nice job Thomas. Looks like a lot of handiwork .... and hard work. I'm guessing you do woodwork in your spare time ?.

[Esser]

Looks nice. What is the chord length overall front to back?

Hey Jim, I went and measured and forgot to post a few days ago. I believe 1.75” was what I measured. I’m not at home now

[bholland]

I also just bought the jury strut fairings from Lowell Fitt and they are amazing.

Brett

[bbs428]

I just finished installing fairings over my horizontal stabilizer struts. I ordered plastic fairing material from Quad City Aircraft, 5' of their smallest size. It is sized for going over 1/2" round tubing, but it works over the 5/8" tubing on the horizontal stab. It is very light but also sturdy. I'm not sure but I believe it is ABS plastic, similar to the Kitfox lift strut fairing material. I scuff sanded it with 220 grit and it took paint quite well.

It is quite a tight fit over the 5/8" struts and I couldn't slip it on by hand, even after greasing the strut. I finally had success by using 6 rubber faced trigger type bar clamps spaced along the fairing and positioned to squeeze the fairing more open. It then slid on with minimal effort. It was easy to properly position the fairing in the airstream with the clamps on. After removing the clamps, the fairing grips the strut very tightly and I decided that no glue was needed to keep it in proper position.

Time for a flight test! After about 1 hour of straight and level testing at 2000' and 5200 rpm (my normal cruise setting), I was able to measure the following results compared to previous testing without the fairings: The fairings gave me a solid 2 mph (maybe even 2.5) speed improvement, and a 0.1 gph reduction in fuel consumption-measured by my fuel flow meter. I believe these results are reasonably accurate and done with as much "apples-to-apples" comparison as I could, but of course I am no Chuck Yeager test pilot. Well worth the effort and cost ($35 + paint) in my opinion. Pictures below.

I think these are the same fairings.

I was going to start a new thread but thought it would be more appropriate here.

I received a quote from Dennis at Aerolite 103 on his small strut fairings, dated 12/16/2022. Two pieces cut at 28" each was 44 dollars plus shipping. Very reasonable imho.

31334

Being plastic, I'm sure they have some weight to them. If you're a bit nose heavy, this would be better than adding dead weight in your tail and maybe pick up some speed!

Streamline Fairings (uflyit.com) (http://www.uflyit.com/streamline_fairings.htm)

Dragonplate makes a carbon fiber fairing, but they are expensive!

Streamlined Symmetrical Airfoil Carbon Fiber Tubing | DragonPlate (https://dragonplate.com/streamlined-symmetrical-airfoil-carbon-fiber-tubing)

Does anyone have a better solution for 5/8 fairings?

[dginok]

I made some 3D printed fairings for the horizontal struts. The latest version has a round opening on the bottom, and the fairing just snaps onto the strut. I printed these in three sections due to height limitations on my 3D printer. Each section is connected to the next via a plastic insert.

The bottom of the fairing is not perfectly smooth due to the snap-on mechanism, but I'm pretending that drag is reduced compared to the raw strut.

31347

31349

[bbs428]

I need to learn 3d printing but I'm on the downhill slide of understanding and $$ for the new 3d printer computer stuff.

Looks very nice dginok! How much $ to print your struts?

[dginok]

Thanks! Material probably cost about $8 max. I'm sure I've used up much more than that with the various versions I've tried over the years.

[jiott]

I just finished installing fairings over my horizontal stabilizer struts. I ordered plastic fairing material from Quad City Aircraft, 5' of their smallest size. It is sized for going over 1/2" round tubing, but it works over the 5/8" tubing on the horizontal stab. It is very light but also sturdy. I'm not sure but I believe it is ABS plastic, similar to the Kitfox lift strut fairing material. I scuff sanded it with 220 grit and it took paint quite well.

It is quite a tight fit over the 5/8" struts and I couldn't slip it on by hand, even after greasing the strut. I finally had success by using 6 rubber faced trigger type bar clamps spaced along the fairing and positioned to squeeze the fairing more open. It then slid on with minimal effort. It was easy to properly position the fairing in the airstream with the clamps on. After removing the clamps, the fairing grips the strut very tightly and I decided that no glue was needed to keep it in proper position.

Time for a flight test! After about 1 hour of straight and level testing at 2000' and 5200 rpm (my normal cruise setting), I was able to measure the following results compared to previous testing without the fairings: The fairings gave me a solid 2 mph (maybe even 2.5) speed improvement, and a 0.1 gph reduction in fuel consumption-measured by my fuel flow meter. I believe these results are reasonably accurate and done with as much "apples-to-apples" comparison as I could, but of course I am no Chuck Yeager test pilot. Well worth the effort and cost ($35 + paint) in my opinion. Pictures below.


After more time testing I have to back off on the 2mph improvement, and be more realistic with 1-1.5mph.

I am impressed with what you guys have done with 3D printing, but I don't see how you can beat these ready made fairings for cost, simplicity, weight, and being one piece with no joints.

[dginok]

I agree Jim! The fairings you have look fantastic.

[efwd]

Jim, remind me of your source for those fairings.

[jiott]

I got them from Quad City Aircraft. They are used on ultralights; I believe they are still available but not 100% sure. Someone recently said they couldn't find them on the QuadCity website and had to call them.

[AirFox]

Attached are some pictures of another way to build strut fairings.

I 3D printed a mold the shape of the fairing. Next I vacuum bagged carbon fiber over the mold. Then printed ribs that fit over the struts. They slide right over the struts. I picked up approximately 1.5mph at 70% power and approximately 3 mph at 85% power.

Scott

[bbs428]

They look great. Impressive!

Scott - Could you break down the costs of doing what you did please and what the final weight was?