Carbon Fiber Tapered RV Wings

Southern Pete said:

Bob,
Sorry for thread drift, how much work was it to swap out your VM1000?
I think that task may be required in my airplane before too long...
Pete

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No worries Pete...and is this Pete P of Portugal racing fame?

The swap was fairly extensive, but worth it. I had been having issues the past several years with transducer failures. The folks at JPI were always helpful, but the parts have been getting more scarce, and are pricey. I was trying to milk the VM-1000 until after the wing project was complete, and I could tackle a panel upgrade from my 20th century EFIS (D100) to an HDX...but when another fuel pressure transducer cost me flying in the Silver final in Reno '21, that was the last straw. I really didn't have the time or wrenching bandwidth to do the full panel, and the JPI EDM-350 was the most do-able intermediate step, as Steve and I worked to finish the wings. So, being a glutton for punishment...and having a really cool wife... I took a gulp, pulled the VM from the right side of my panel, and the DPU from under the left side of the glareshield up near the firewall (original build locations), and got busy.



The wiring for the 350 was extensive, and required pulling all the VM-1000 wiring, data tapes, sensors and CHT/EGT probes (they did not work with the EDM-350, and I doubt they work with most other newer systems).



I decided to put the 350 on the left side of the panel, next to my D100, where my D10A was, so I'd have EMS data in front of me. It's a great upgrade for racing...no more looking cross-panel at 50 feet! I moved the D10A to the right side where the VM1000 was, which puts PFD data in front of friends I take flying...a common complaint when I take another pilot up and they fly...they didn't like looking cross-panel for data either. I didn't want to make all new panels until I do the final panel upgrade down the road, so I fabbed up some brackets and filler plates to make the installation look a little less scabbed on.







I'm pleased with the way it came together, and it will be nice to have EMS data logging during testing and racing.





I did functional checks while we were finishing the wings, and did a few taxi tests to ensure that everything worked before flying the first flight with the wings. That did add a level of complexity and focus on that first flight. I had gone past the point of no return on the wings when I did the 350 install, or I would have preferred to test fly the 350 on its own. But it has been working well during flight test, so I'm very happy with the results! And my buddy Scott back in Reno gets all the parts as spares for his 2 RVs with VM-1000s

F1Boss said:

I recall I had to have the high stop to 39.5 deg (3 Dec 2012). If you want to follow what Hartzell did for me, have at it! I suspect all of the Rocket props were reset to that setting after I did some test flights for them.

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I'll be talking to Jim at WW about this very thing. Thanks for sharing your experience and data on this, Boss!

Cheers,
Bob

DanH said:

The wing is really cool. Goes faster, looks great. You guys are a dream team.

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Thanks Dan, I'm just happy to be here...or as Peter Venkman said in Ghostbusters, “I love this plan! I’m excited to be a part of it! Let’s do it!”

DanH said:

Bob, 23.3" at that speed/altitude/temperature is impressive. May I ask the cowl intake diameter, and did you see an indicated MP increase when you swapped to the taper tube Sky Dynamics manifold?

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The cowl inlet is a 3" Sam James inlet that I added several years ago.



The engine originally had a Bendix RSA-5 servo, and a home-brew inlet. When I added the Sam James cowl Inlet, I used the standard SJ filtered inlet, and experimented with various inlets over the years (the second pic is one I molded around a low-drag VW exhaust pipe, suggested by, and lent to me by, an aircraft engine mechanic in Reno-Stead...please don't cringe too much )





The original sump was an updraft sump with an elbow to re-direct the air from the James inlet. I really wanted a forward facing cold air sump, but obtaining a Sky Dynamics model was difficult. Back in 19, they had a 6 month wait, and told me if they got a big order from Carbon Cub, it could balloon to a year. I got really lucky one day when talking with Ken at Lycon, and told him what I was trying to do. He said he thought he had a couple left over from doing Red Bull racer engines, and if he had 2, he'd sell me one. He also had an Air Flow Performance FM-300B new in the box, so I was able to buy both! So with parts in hand, I fit-checked everything, and it all came together nicely.





On the back of the SJ inlet ring, I have a 3" to 4" silicone coupler/expander, and on the servo, I have a 4" silicone tube. I use a body-builder elbow brace to span the 1" gap between the two silicone tubes (those fellas have really big elbows! ).



It's unfiltered at the moment (Ken and I discussed this, and he said none of the Extras in RBR used filters...of course they had larger budgets than I do). Steve and I have been discussing a larger inlet in the cowl, and if we do that, we'll explore filter options as well.

I feel I saw about a 1.5" increase in MP between the RSA-5/updraft system and the FM-300/SD forward facing cold air system. I can see 31"+ on takeoff at sea level, so I actually don't use full throttle on SL takeoffs any more, to ensure I have margin to detonation. Steve felt strongly that I could be pushing that margin at 31", and I agree.

Dan, I'm wide open to thoughts on how to improve induction flow, and thanks for your comments about the wing project! It's been, and continues to be, lots of fun!

Cheers,
Bob

rvmills said:

Thanks Dan, I'm just happy to be here...

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I think that every morning...

Steve and I have been discussing a larger inlet in the cowl ...

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If I have my numbers right, going to a 4" ring would be worth 0.33"hg at the illustrated cruise values.

I feel I saw about a 1.5" increase in MP between the RSA-5/updraft system and the FM-300/SD forward facing cold air system.

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Considering only the throttle bodies, my notes say the difference would be about 0.75" hg at 1560 lbs. Your 540 probably flows more, which would increase the difference a little. The other 0.75" would have to be due to the manifold system. That seems entirely possible, given the old setup was an updraft sump.

23.3" seems high for the conditions a few posts back. Breathing through a 3" inlet, at 9500, 54F, 230 RPM, 0.95 VE, and 218 KTAS, static pressure should be 20.98" with a pressure rise of 1.09", a total of 22.07" before the throttle body. Typically there would be some subsequent downstream loss for the intake plumbing (it's about an inch for my 390). Here, for 23.3 to be valid, the taper pipe manifold would have to be doing something interesting, perhaps due to increased velocity at the port (the taper), or better wave action, or both...an increase rather than a tract loss.

A differential manometer would tell. One static tap at the tube in front of the FM300, and one at a primer port, or better, an accumulator tapping several ports.

DanH said:

If I have my numbers right, going to a 4" ring would be worth 0.33"hg at the illustrated cruise values.

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That's about 1.3 mph...Sounds very worthwhile to me!

DanH said:

Considering only the throttle bodies, my notes say the difference would be about 0.75" hg at 1560 lbs. Your 540 probably flows more, which would increase the difference a little. The other 0.75" would have to be due to the manifold system. That seems entirely possible, given the old setup was an updraft sump.

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Concur...I think flow path management was a big factor here.

DanH said:

23.3" seems high for the conditions a few posts back. Breathing through a 3" inlet, at 9500, 54F, 230 RPM, 0.95 VE, and 218 KTAS, static pressure should be 20.98" with a pressure rise of 1.09", a total of 22.07" before the throttle body. Typically there would be some subsequent downstream loss for the intake plumbing (it's about an inch for my 390). Here, for 23.3 to be valid, the taper pipe manifold would have to be doing something interesting, perhaps due to increased velocity at the port (the taper), or better wave action, or both...an increase rather than a tract loss.

A differential manometer would tell. One static tap at the tube in front of the FM300, and one at a primer port, or better, an accumulator tapping several ports.

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I'm game...perhaps you, Steve and I can go offline and develop the tap design and ensure I have the right D-Manometer. My last attempt at doing a DanH test was checking for a pressure drop in the case from the ASA vacuum vent valve. I had a tube tapped into the breather and another to the static, and could read no diff. I think I bought the wrong manometer online , or I just had no diff. I fired my test engineer in the mirror . Open to this option...I know Steve loves to do this stuff too!

Cheers,
Bob

rvmills said:

I can see 31"+ on takeoff at sea level, so I actually don't use full throttle on SL takeoffs any more, to ensure I have margin to detonation. Steve felt strongly that I could be pushing that margin at 31", and I agree.

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Bear in mind, this was with 10:1 CR and timing set at 29° from the EI. So, yeah, I think he was pushing it a bit. The center electrodes on his spark plugs had kind of a porous look to them.

We now have the timing at, I think, something like 22°.

scsmith said:

Bear in mind, this was with 10:1 CR and timing set at 29° from the EI. So, yeah, I think he was pushing it a bit. The center electrodes on his spark plugs had kind of a porous look to them.

We now have the timing at, I think, something like 22°.

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Prior to the new servo, I had timing set to 23.5 on the EI and 25 on the mag. That is the EI setting with no MP input. The EI curves did advance the timing up towards 29 during takeoff in Reno, but detonation was less of of a factor that high.

After the new servo went in, I set the timing of both mag and EI to 22.5, but still kept the MP sensor on. That's when we saw more advance at SL than we liked, and I started doing less than full power takeoffs at SL (Steve's recommendation).

For racing Reno in '21 with N2O, I backed timing to 22 on both, and turned the MP sensor off, essentially giving it fixed timing.

I have the MP sensor back on now for testing, especially LOP cruise testing, but I do manage the power down low with detonation margin in mind. I think that was very good advice from you Steve!

Cheers,
Bob

rvmills said:

No worries Pete...and is this Pete P of Portugal racing fame?

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Hi Bob, thanks so much for so much detail! Yes, I have been to Portugal a couple of times...! Now flying an RV-6 that has a VM1000 suffering the same symptoms as you and trying to figure out the best way ahead.

Your project is one of the most innovative on here, really interested to hear how you are getting on. Sorry I can't offer anything insightful to help you on your way.

rvmills said:

So I think that at least partially answer's BillL's question. At 2300 and 212-214 yesterday, and at 218 today, I was governing, and saw no RPM changes when I started the descent and accelerated. But if I try to govern it to a slower speed, I do hit the stops, and it won't go any coarser. Is your question expressing concern that at full power in racing, we may hit the stop and then be speed limited by that...or subject to a runaway?

Just describing all this to get BillL's feedback, and to generate discussion. I'll discuss this with Jim at WW too. He and I have discussed other prop possibilities as well.

Thanks for the discussion!

Cheers,
Bob

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Bob/Steve - - I'm flattered but am at my limit to provide real help. This was first encountered with my hartzell composite with that wide blade. I could not reduce WOT RPM below 2400 at some altitudes (speed) all level flight. If the throttle is reduced the RPM regulation can go lower. My prop coarse stop is 20 something deg, so it hit the stop a much lower speed than yours. (i will update the #)

My question was yes, when you get to full power and then descend will it hit the stop. To your question "Will it runaway?" Hard to say precisely, but if WOT and descending if it hits the stop the the rpm will increase until power is absorbed. Probably not a runaway, but if your equipment is already at a limit then The reason I brought it up is for something to check and avoid a surprise. A nose over at WOT with slowly increasing airspeed at the end of the program could obviously find the limit safely, the RPM excursion could found/controlled within reason.

Thinking out loud *warning* I'll bet if you documented the conditions at lower RPM settings like 2300, 2400, 2500 (2600?) with a WOT-nose-over (pick your DA) to define the speed at which the RPM increased beyond setting, it would help Jim project the stop limit for race speed conditions.

I only know what happens on the stop as I chased a "governor problem" for 6 months and $$$ before understanding how the system works and behaves.

Anyway better guys than me to address it. Great information - thanks for time to post and allowing us to share.

I spoke with Jim yesterday, and my results are normal thus far, and not a cause for concern. At WOT and 2300 RPM, when I descended and accelerated to 220-230 KTAS, the RPM remained solid at 2300. I reduced MP to 20" to slow the descent, and was a bit high on path, so I tried reducing RPM, versus reducing MP more, to slow a bit while not pulling MP back too fast. That's where I hit the coarse stop and could not go below 2200 RPM. Reducing power is a better choice in this scenario (it just requires good descent path planning so you don't get high on path). In that descent, and subsequent tests the next day, I also experimented with raising and lowering the nose a bit, and I was definitely on the stop above 215-220 KIAS, so the prop accelerated and decelerated a bit with speed increase and decrease (behaving like a fixed pitch prop). Nothing like a runaway though.

During the high speed flutter clearance tests, I was at 9500, near WOT and at 2400 RPM. To get to the higher speeds, I did a 1000 fpm descent, and the prop remained at 2400 on each test, all the way to 262 KTAS, the fastest speed I allowed the plane to reach. So I was not on the stop there.

Future tests include a 4-way GPS speed test at 5,000' (Reno-like), at full power/2700 RPM (no N2O yet). After I take the 4 readings, I'll descend slightly and accelerate, and ensure the RPM does not increase. Pre-Reno tests will include N2O tests, but that won't happen until I'm in full race config, including water spray.

This is a valuable discussion. Ensuring that I'm not on the coarse stop in the chute or on the course in Reno is a critical data point. I will say that I have not seen any tendency to have RPM increase there, and have been up to about 245 KTAS thus far. Chute management will be important, and I may not need N2O in the chute at all now (I used it a bit in '21 at the low end of the chute, to stay in front of a Glasair III, but we had nice flat start. I'd actually prefer not to use it till we're down on the course.

Fun stuff to discuss, eh!

Cheers,
Bob

rvmills said:

I'm game...

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Bob, rather than muck up this thread further, I've started a new one here:

https://vansairforce.net/community/showthread.php?t=213274

Obviously wing testing comes first!

DanH said:

Bob, rather than muck up this thread further, I've started a new one here:

https://vansairforce.net/community/showthread.php?t=213274

Obviously wing testing comes first!

Click to expand...

Thanks Dan. Read that thread too, and will jump in after a few more flights.

Cheers,
Bob

Two more test hops today. First was an attempt at gathering some climb and glide data, for Vx, Vy and Best Glide numbers. Pretty dynamic test, and gathering good HUMINT data proved challenging. I have some, but don't trust it enough to give a good Vx/Vy. I have Foreflight logs, but that is a bit arduous. Still trying to figure out if track data is available from my GNX-375. ADS-B data is in there, but can't be read by any program I have, and a call to Garmin said that was more for their internal use . Anyone have the gouge on GNX-375 track data?

I'm going to point a GoPro at the panel next time.

Did a little basic aerobatic eval as well. Roll rate seems on par with my old wings, which was slightly slower than the average RV, as I had those clipped wings with shortened ailerons. Under 3 seconds for a full deflection aileron roll, so perhaps 150° per second? Lots more eval ahead for more maneuvers


Hop two was a cruise check at 13.5, 15.5 and 17.5. With the Mod 0 racing tips on, it appears TAS drops off a bit above 13.5, but as Steve points out below, efficiency goes up nicely. Steve and I plan to make X-C tips that add a foot of span (and lights!), and we'll compare results when we do that.

My old wings' performance dropped off even more sharply above 13 or so. These hung in fairly well, though I added a little RPM up higher.

218 KTAS at 13.5 at 64% power/12 gph
213 KTAS at 15.5 at 59% power/10.9 gph
211 KTAS at 17.5 at 46% power/9.7 gph

The JPI EDM-350 is new, and I'm still checking the fuel flow accuracy, and getting used to the lean find function (seems to match my AFR pretty well...or vice-versa).







Descent from 17.5 will require good planning. Starting at 17" and 2450 RPM, I reduced to 2300, and reduced 1". 500 fpm resulted in 225 KTAS, and 1000 fpm went right to 230, 231 (whatever it takes )

I just kept dragging an inch at a time as MP climbed in the descent, and below about 12-13K I could descend at 1000 fpm and stay at 220 KTAS.

Up at 17.5K is similar to a jet near the top of its envelope...a bit of a pencil-point balancing act. Not horribly so, but a bit of that feel. These wings could go higher, especially with X-C tips, but I think the heart of the envelope may be down around 12-14K. We'll see

Cheers,
Bob

rvmills said:

218 KTAS at 13.5 at 64% power/12 gph
213 KTAS at 15.5 at 59% power/10.9 gph
211 KTAS at 17.5 at 46% power/9.7 gph

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At 17.5K you are going 96% as fast on 80% of the fuel!!! I'm not sure I would call that a "performance drop off". At 17.5K, you are getting 25 MPG. Geesh, demanding customer, eh?

scsmith said:

At 17.5K you are going 96% as fast on 80% of the fuel!!! I'm not sure I would call that a "performance drop off". At 17.5K, you are getting 25 MPG. Geesh, demanding customer, eh?

Click to expand...

Corrected my statement to reflect the drop only in TAS, but recognized the increase in efficiency. Perhaps I was too tired for math at that point…or could it be…



Cheers,
Bob

scsmith said:

At 17.5K you are going 96% as fast on 80% of the fuel!!! I'm not sure I would call that a "performance drop off". At 17.5K, you are getting 25 MPG. Geesh, demanding customer, eh?

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I can't wait to test with the long wingtips!

airventure cup

I'm planning on trying my GP-4 out. I would love to see these new wings in action

Wow! What a great thread. After a 13 year hiatus from RV land, I find this. You're living the life of experimental aviation.

The RV-15 brought me back, but I still remember the wonderful RV-8, and this makes me want to build another and go racing!

It has been a while since you updated this thread, I assume you're busy flying and tweeking and having fun. A good showing at Reno!

Best wishes to you all, John

Nice, really. Looks like a great wing design, Steve.

Nuisance said:

Wow! What a great thread. After a 13 year hiatus from RV land, I find this. You're living the life of experimental aviation.

The RV-15 brought me back, but I still remember the wonderful RV-8, and this makes me want to build another and go racing!

It has been a while since you updated this thread, I assume you're busy flying and tweeking and having fun. A good showing at Reno!

Best wishes to you all, John

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Hi John! So awesome to hear from you! You were the inspiration for many things we've done over the years, and I still remember ogling over your beautiful (and super-fast) 8. Hope to see you out there someday soon!

Thanks for the compliments...Steve did create a beautiful set of wings!

Here's a copy of the post I just made in response to a question about racing comparisons between new and old wings.

See you soon!

Cheers,
Bob

Scott (Freemasm) and the VAF Gang,

Coming up for air after getting back from Reno, then dashing off to a SWA bud's retirement, and doing a short work trip. Now reconfiguring Rocket Six back into the "normal RV grin" mode.

Rocket Six has raced in Reno 10 times since 2011. We missed 2016 with a cracked engine mount repair, 2020 due to COVID, and 2022 as the wings were in final install mode, and we didn't want to rush it.

The year to year comparison that Scott asked about is 2021 vs 2023. That is the last year with the Harmon Rocket style clipped metal wings, vs the first year with the new Smith Aero Carbon Fiber Tapered wings. Here is a numbers comparison. Keep in mind that year-to-year, even day-to-day comparisons, are somewhat impacted by the temperature, winds, turbulence, and "meat-servo" performance. All speeds are MPH.

2021

Qualified 16th in Sport @ 262.354 (Started 8th in Sport Silver)
Heat 1B (6th Silver): 252.504 (this speed bumped me down to Bronze)
Heat 2C (1st Bronze): 262.223 (this speed bumped me back up to Silver)
Heat 3B (7th Silver): 263.838
Silver Final: Scratch due to FP transducer failure during taxi out

2023

Qualified 23rd in Sport @ 268.460 (Started 7th in Bronze)
Heat 1C (5th Bronze): 257.991 (this speed bumped me down to Medallion)
Heat 2D (1st Medallion): 267.323 (this speeds bumped me back up to Bronze)
Heat 3C (3rd Bronze): 269.662
Bronze Final (5th Bronze): 268.964

General Analysis: At initial glance, one might postulate that the wings increased the max qual and race speeds by about 6 mph. I'm not sure that would be a fully-accurate conclusion though, as there were many variables in play. It would be nice to have more years of flying the same course in Reno, to continue to refine the line and the technique with the new wings...I honestly think we could be faster...as I learned much during the week, and have replayed the races many times, and have strategy I would like to try. Unfortunately, that won't be the case, as this was the final year for the races in Reno.

In both 21 and 23, the N2O system and water spray cooling required a lot of tweaking to dial in. To be honest, I don't think it was ever at 100%...we were chasing cooling issues both years. In 21 we worked a lot on the water spray nozzles to get CHTs in line. In 23, we had N2O system issues (clogged jets and other small malfunctions), and we experimented more with water spray nozzles, and a new-for-'23 ADI system (water-methanol Anti Detonation Injection). We got close, but I was still richening the mixture a bit more than I had hoped during the races, to keep #5 and/or #6 CHTs from running away.

In both 21 and 23, after a good qualifying period, we had issues that slowed us down in Heat 1. As we dialed it in, we got back up to the speeds we qualified at, and then went faster in later heats.

While that 268.460 qual this year was the 5th fastest of all time for Rockets or RVs, it fell short of the 276.899 posted by Todd Rudberg (RV-8 with N2O), which is the fastest Metal Mafia speed ever at Reno. Bill Beaton (HR-II with SC) is right behind at 276.132, with Neil Wischer (RV-8 with N2O...271.954) and Chris McMillian (F1 Rocket with N2O...270.260) the only other Metal Mafia pilots to qualify over 270.

However, we were very happy with that 269.662 mph average speed for Heat 3C, as that was the second fastest RV or Rocket full-race average speed ever. Bill Beaton holds that high mark, at 272.940. During that race, we passed a Lancair Legacy on the start, and gave chase to a Glasair III the entire race...all while hauling around our fixed gear. Perhaps the most fun race in my Reno career, and I think the strongest testament to the performance increase provided by Steve Smith's awesome wings!

One of the most exciting things to have seen during the 2011-2023 period, is how fast Sport Class Air Racing has become. Jeff Lavelle set a new record of 410.635 mph this year, with Andy Findlay right behind at 406.107. Those two, and Jon Sharp, are the elite Sport Class 400 club...WOW!

In that same period, we added 30 mph to our Rocket Six qualifying speed, and 29 mph to our average race speed...while dropping from Second in Bronze in '11 to 5th in Bronze in '23. Just a testament to the popularity, innovation, and experimentation within out Race Class...the class for Experimental Aircraft! We did move from hunting HR-IIs in the early days, to hunting F1 Rockets, Legacies, and Glasairs these days. I want to give a shout out to my two amigos that also flew Sport 49, while I was playing with a Thunder Mustang, a Glasair III, a Legacy and an L-39. Shane Margraves and James Stringer did a phenomenal job flying and racing, and will always be a part of the plane's legacy! Another big shout out to Crew Chief and Airshow Wingman extraordinare, Sean "Goose" Farrell. Best of the best!!

Thanks to the many VAF friends and family that stopped by the pits this, and every, year! It has always been great to share the fun of racing with everyone, and I know Steve really enjoyed talking with the many folks that stopped by to ask questions about the wings.

This year Sport Class Air Racing and it's new subsidiary, Sport Air Racing Council, earned FAA accreditation to conduct single-class Sport Class Air Racing. Our first event is October 21, 2023 at the Las Cruces, NM Air and Space Expo. We sure hope to see many of you out there, and we'll post future events as we build them!

Here's some photos from Reno '23:

James, Sean and Steve out in the staging area:


Taxi out:


Rounding a pylon:


That's a turbocharged Legacy trying to get by (he did):


Fun race in Heat 3C:


Chris in 96 giving chase in the Bronze final:


Just before Home at the finish of the Bronze Final:


Just after Home at the finish of the Bronze Final:


I reckon the sign says it all!


Cheers,
Bob

Sorry if this has been asked and answered here. Long thread. Also want something other than the state of Vans Aircraft speculation

How did you solve/what actions taken to avoid the CF-Al galvanic corrosion potential?

Freemasm said:

Sorry if this has been asked and answered here. Long thread. Also want something other than the state of Vans Aircraft speculation

How did you solve/what actions taken to avoid the CF-Al galvanic corrosion potential?

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Hi Scott,

We never allow aluminum and carbon fiber to be in contact.
In places were aluminum brackets, fuel filler neck, things like that, are bolted or bonded to the carbon composite, we either put down an insulating layer of fiberglass cloth, augmented by the epoxy primer on the aluminum and the high-strength epoxy bond line, or we bond a block of Garolite G-10 (which is really just pre-made fiberglass built up to useful size sheets) and bolt to that.

A typical place where we would use G-10 is when bolting a bracket to either a carbon web that is thin, just 3--4 plies typically, and needs local stiffening, or when bolting through a carbon-foam-carbon sandwich and we don't want to crush the foam, we replace the foam with a block of G-10. When we plan ahead for it, we would incorporate that G-10 block into the sandwich layup. When something unanticipated is bolted on, we use a hole saw to cut through one side of the carbon sandwich, carve out the core, bond in a replacement block of G-10 (cut with the same hole saw) and then cover back up with a carbon ply, followed by a fiberglass insulating ply. Then the bracket can be bolted directly to that structure.

On our L-39 Jet wingtips, we bond the aluminum attachment strips to the carbon layup, but with a special procedure. The aluminum is treated and primed with a combination of AC-130 SolGel and BR6747 epoxy primer. This process is what Boeing uses. Then, of course, the treated aluminum is bonded to the carbon with a high-strength epoxy (Hysol 9360), so we get the added insulation from that bond line as well.

Wow, this is really experimental aviation. You actually build and developed what I was dreaming and playing on paper as an amateur. You are a brilliant team of experts in all areas working together and you shared all this for us in completely detail. This post is a treasure.

I have being spending my time just working out how to build a tapered wing (not as much as these) with the Roncz wing tips design for the 230XX airfoil. And work out a MDO so I slightly optimized the 23013.5 airfoil for the complete wing. Check for structural loads and work it in Ansys composite to check deflections and weights. I dream to make my own composite wings on my RV and this thread motivated me to do so.

Kind Regards!

DB

scsmith said:

On our L-39 Jet wingtips, we bond the aluminum attachment strips to the carbon layup, but with a special procedure. The aluminum is treated and primed with a combination of AC-130 SolGel and BR6747 epoxy primer. This process is what Boeing uses. Then, of course, the treated aluminum is bonded to the carbon with a high-strength epoxy (Hysol 9360), so we get the added insulation from that bond line as well.

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Hi Steve,

I am just a mechanical engineer with experience in engine development and machining but these last years I am learning a lot about composites. Started doing small parts and now pretending to do bigger ones. It will help a lot for my application if I use AC-130-2 to treat aluminum and then use the BR6747 to coat the part to be place in the mold between CF layers and vacuum infuse it. Instead of using GF to insulate the metal. You stated that you used both methods in the wings construction, is there a reason to use GF instead of the epoxy coating?



Thanks in advance for your reply.

Dabb said:

Wow, this is really experimental aviation. You actually build and developed what I was dreaming and playing on paper as an amateur. You are a brilliant team of experts in all areas working together and you shared all this for us in completely detail. This post is a treasure.

I have being spending my time just working out how to build a tapered wing (not as much as these) with the Roncz wing tips design for the 230XX airfoil.

Click to expand...

I wasn’t aware that John had designed a wing tip for the NACA23000 series airfoil.
Can you point to any references for that?

rvbuilder2002 said:

I wasn’t aware that John had designed a wing tip for the NACA23000 series airfoil.
Can you point to any references for that?

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I attached here the 2015 patent for his design. I used it as a base from where to start and figured out the details which are not there by and MDO/CFD approach. But 90% its there.

Dabb said:

Hi Steve,

I am just a mechanical engineer with experience in engine development and machining but these last years I am learning a lot about composites. Started doing small parts and now pretending to do bigger ones. It will help a lot for my application if I use AC-130-2 to treat aluminum and then use the BR6747 to coat the part to be place in the mold between CF layers and vacuum infuse it. Instead of using GF to insulate the metal. You stated that you used both methods in the wings construction, is there a reason to use GF instead of the epoxy coating?



Thanks in advance for your reply.

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The AC1-30 SolGel followed by the BR6747 primer is an expensive and tedious process. It is hard to buy the materials in small quantities, although we have one supplier that has been very gracious in letting us buy small amounts. We use it in this particular application because the bond is structural.

Most of the time, you are putting a metal insert into composite to provide something to thread fasteners into, or something to clamp down on, or local stiffening, where the bond itself is not particularly structural. In those situations, it is much simpler, faster, cheaper to just use a fiberglass insulating ply.

Dabb said:

I attached here the 2015 patent for his design. I used it as a base from where to start and figured out the details which are not there by and MDO/CFD approach. But 90% its there.

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That is a fairly nice looking wingtip, pretty similar to what we have been doing for years. I think the patent would be invalid based on pre-existing art.

scsmith said:

That is a fairly nice looking wingtip, pretty similar to what we have been doing for years. I think the patent would be invalid based on pre-existing art.

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I just don´t know if its valid or not, thats out of my understanding as a mechanical engineer who make of keeping things as simple as possible a law. But for me it gave me a very good guidance in developing my model and saved me a lot of computing time. I dont have the experience and studies you have, so looking at the work of Roncz or what you did in this post, its a great guidance for me.

scsmith said:

The AC1-30 SolGel followed by the BR6747 primer is an expensive and tedious process. It is hard to buy the materials in small quantities, although we have one supplier that has been very gracious in letting us buy small amounts. We use it in this particular application because the bond is structural.

Most of the time, you are putting a metal insert into composite to provide something to thread fasteners into, or something to clamp down on, or local stiffening, where the bond itself is not particularly structural. In those situations, it is much simpler, faster, cheaper to just use a fiberglass insulating ply.

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I buy lot of things from USA, but some things as certain CFs twills and titanium alloys are restricted by US government to be sold abroad. And I bet these products are banned. I am in a very remote place on Earth, near the south pole.
I am mostly doing coupons and small elements right know, learning and breaking stuff. Adjusting my results in FEA to what I have in the real world and trying not to mess with laminates that are not balanced and quasi-iso in order to make my amateur FEA analysis easier to predict.
You gave me really good information posting the products you used, so I can check their datasheets and look for a replacement.

I wonder which improvements are you going to make in your design for your new RV8.

Dabb said:

design for your new RV8

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Wondering... about the whole thread really. Are we talking RVs here, as in Van's RVs?
Hats off and respects to any improved/new/experimental design, but please don't call this an RV... Dick might not agree either.

Why graft a CFK wing to an aluminum fuse? Why not design a carbon fuse to go along? Sure, the wings have now kinda proven themselves no doubt, but surely reducing some of the wetted area on a slick carbon fuselage would bring some (speed) advantage, or am I am completely off?

Dan 57 said:

Wondering... about the whole thread really. Are we talking RVs here, as in Van's RVs?
Hats off and respects to any improved/new/experimental design, but please don't call this an RV... Dick might not agree either.

Why graft a CFK wing to an aluminum fuse? Why not design a carbon fuse to go along? Sure, the wings have now kinda proven themselves no doubt, but surely reducing some of the wetted area on a slick carbon fuselage would bring some (speed) advantage, or am I am completely off?

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Because then he can’t hang out with the “Metal Mafia” crowd!

Dan 57 said:

Wondering... about the whole thread really. Are we talking RVs here, as in Van's RVs?
Hats off and respects to any improved/new/experimental design, but please don't call this an RV... Dick might not agree either.

Why graft a CFK wing to an aluminum fuse? Why not design a carbon fuse to go along? Sure, the wings have now kinda proven themselves no doubt, but surely reducing some of the wetted area on a slick carbon fuselage would bring some (speed) advantage, or am I am completely off?

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Dan 57,

Greetings from across the pond. I've flown a few HB registered aircraft in your neck of the woods...one of prettiest places in the world. I have great friends near you in Interlaken (racing buddy and family).

Hope you're not wondering too hard "about the whole thread really." It's been a fun, challenging project, born in the mind of the NASA Aerodynamicist that also consulted with Van and team on the design of the RV-10, RV-14 and RV-15 wings, and who recently was one of the panel of experts on the Van's update video. Van has seen the wing project in work, and knows Steve well. It has RV in its DNA, and I/we respect that heritage, while definitely (and carefully) delving into the experimental design area. Just keepin' it positive! Is it an RV, a Super Six, a Rocket...a little bit of all? Yep. However, when posting build or performance information (which I'm about to update), I/we don't try to say this is RV-6 performance.

The decision to graft carbon to metal was part of the original design decision-making matrix, at the beginning of the project. We discussed building the wings in metal, and weighed the advantages and challenges of composites. The performance enhancement was worth the challenge to us. Would starting with a clean sheet and making a new CF plane that reduced wetted area be faster? Perhaps...so you are not off the mark. I believe Steve's original dream was to build a wing that would enhance the performance of an already fantastic (and well-proven) airframe. We just started with my airframe first, because I race, and I was willing to dig in with Steve and Bob K, and modify my airplane (further). To now extend what we learned to building an 8 for Steve, with the new wings and other strength and safety mods that he has developed, would bring that dream to flight. Pretty cool in my book!

As to what Taltruda Tom said:

Taltruda said:

Because then he can’t hang out with the “Metal Mafia” crowd!

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Now that's funny...and true! They still let me hang out, but barely...and not without copious amounts of heckling and teasing. Then again, I just smile in the rear view mirror at them on the race course!

Doing some VAF catching up, and thought I would provide an update after the first condition inspection with the new wings, after 160+ hours and one (last) Reno race season with them (future racing with Sport Class to come!). Also, just back from a formation flying weekend in UT that provided more X-C performance and LOP testing opportunities to report on. Finally, and first up, just did a flyover of ball game this past weekend near home in TX, and we received the following photo. Second photo is edited by me, as it provides a neat comparison of the RV-6, 8, 9 and S-6 wing planforms.





Sent those to Steve and Bob K this morning!

The first condition inspection with the new wings was completed in Feb, and armed with a checklist from Steve of additional items to look closely at, I took a few extra days to conduct it. Focus items were the spar-to-aircraft connection bolts and high strength splice plate bolts, the composite construction integrity, the security of the mounting pads for all internal wing components, the wing attach points and wing retainer pins (the interface between the metal stub spar and the main wing spar), all of the control connections, the flap connections, the fairing fit, and the wingtip connections. Everything is looking great at this point. Gripes were a slightly seeping smoke oil connection in the wing root, and I seem to be having some seeps in the quick drain o-rings. I pulled some of the wingtip and wing root red paint off when removing the Reno speed tape...should have pulled it right away.

With respect to cross country performance, I continue to be super-pleased with the results of Steve's design. With 55 gallons of fuel (24 L, 24R, 7 AUX) I've done a few 800+ mile legs, cruising at 207-215 KTAS (various altitude/temperature combinations). This past trip from 07TS to BRG (Belen, S of ABQ) to SGU (St. George), then back via Alamogordo (to do an HRII pre-buy for a friend's son), was a good opportunity to test at 8,500, 10,500, 13,500 and 11,500, respectively (per leg). Tests were conducted at WOT and 2350 RPM, with mixture slightly LOP. I'm working through injector balancing again, as we had re-sized some injectors for Reno racing with N2O. Still narrowing it down, so I can't quite go "really" LOP. This trip I was in the low 15's to high 14's in AFR. One skewed item in this set of tests was that my cowl flap is stuck open...didnt have time to trouble shoot it before the trip to SGU. Closing the cowl flap is worth 4 KTAS typically, so these numbers were very encouraging...of course it was a nice cool late winter morning, and the DAs were low.

Here's the result at each altitude:

Leg 1: 8,500', 24", 2350 RPM, 13.0 gph, 215KTAS



Leg 2: 10,500', 22.5", 2350 RPM, 11.7 gph, 211 KTAS



Leg 3: 13,500', 19.8-20", 2350 RPM, 11.1 gph, 209-212 KTAS. This leg had a little variation, with some mild up and down-drafts. It stabilized between 209 and 212 KTAS. Stayed at 212 for quite a while. I feel I was a little closer to peak FF on this leg, and it appears 2 is running about 20° leaner than the rest...that's my next injector swap.




I think I had my best GS ever in 49VM on this leg too! Happiness is...



Leg 4 was quite bumpy at 11,500, so data was "dirty", and I climbed back to 13,500. There the numbers were similar to leg 3...I'll call it 211 KTAS.

A quick Reno 2023 report can round this out. We went with a plan to run 100 HP of N2O, versus the 50 HP we used in 2021. 100 turned out to be too aggressive, and I couldn't keep the cylinders cool, even with ADI injection and water sprayers. We tried 50 and 75 HP shots, and kinda chased...but never found...the magic formula of N2O/fuel nozzles, normal fuel injectors, ADI injection and water sprayers to bring it all together. We had good performance, with a qualifying run of 268.460 mph, but well short of the RV/Rocket record of 276.899. That puts Sport 49 at 5th in Rocket RV qualifying runs. The best run of the week was Saturday, with an average speed for the full race of 269.622, which ranks second all time in Rocket/RV full race average speeds. It was lots of fun running with Legacy, Glasair III, and F1 Rockets, and our final Bronze race on Sunday was one of the closest finishes in memory...and a really fun race. Chris in Sport 96, in an F1 Rocket (with an unknown mondo amount of N2O ) flew a great final turn, and got me at the finish line, as we were both chasing a few planes with no wheels hangin' down. Big fun!

Old wing to new wing racing comparison, between 2021 and 2023 (wings were being installed in 2022, and I raced a Legacy instead)...was a 6 mph increase in qualifying and max average speed from old to new. Factor in that we really don't feel like we had a dialed in N2O set up in 23, versus 21, and I think we could have gone faster. No excuses though, and we'll never have Reno to test it again...so on to new racing horizons (and likely without N2O...still gonna work on the never-ending drag clean-up program!) With respect to X-C performance gains, I feel good about saying the wing was a 10mph boost...perhaps 12. Steve always said it was gonna be a lot of work for 10...but it was all about the journey...and the fun...and the education from some really smart guys!





Photo Credit Kevin Eccles.

Look for more Sport Class Racing in 2024...we are working hard to keep air racing alive and well! More reports on the Steve Smith Aero wings to come...and see you in OSH!

Cheers,
Bob

Thanks for your personal chime in Bob, and yes, you're right, this is what we call Experimental aviation
At the same time I'm also following some other projects, for instance the DarkAero, and this probably skewed me and made my perception of an aluminum/carbon marriage seemed kinda incongruous. Admittedly, the painted wings have now greatly alleviated that feeling

Whatever, congrats to the whole team, and thanks for sharing what sure is a fascinating facet of an RV's evolution.

rvmills said:

Greeting from across the pond. I've flown a few HB registered aircraft in your neck of the woods...one of prettiest places in the world. I have great friends near you in Interlaken (racing buddy and family).

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Though overcrowded and overbuilt in the flatland, the mountainous regions of the country still offer some stunning scenery and a good playground.
Aviation is a small world, as I've now met and been entertained by James a few times on the ol'continent, last in Fall savouring some cold refreshments in either France or the UK.

Dan,

Steve's (and the team's) approach to the carbon wing on an aluminum fuselage has been considered and careful. Steve posts on it in various places earlier in this thread...and there some neat, innovative ideas he brought to the table to make it happen. This was never intended to be a 400 mph racer, to chase Super Legacies and Super Glasair IIIs. We've talked about such a machine, and Steve has consulted on various designs. An all-composite screamer from a clean sheet would be an incredibly fun project. That is one of those wish list planes that Steve and I put right up there with a scale Spitfire for him, and a scale Corsair for me. Time and money...that's all we need!

Very neat you've met up with James! Great guy, and great pilot. Outside shot we may come out to Switzerland to do some Bücker formation training. If it happens, we'll let ya know. Perused your website...looks like lotsa fun going on out there!

Cheers,
Bob

Dan 57 said:

Thanks for your personal chime in Bob, and yes, you're right, this is what we call Experimental aviation
At the same time I'm also following some other projects, for instance the DarkAero, and this probably skewed me and made my perception of an aluminum/carbon marriage seemed kinda incongruous. Admittedly, the painted wings have now greatly alleviated that feeling

Whatever, congrats to the whole team, and thanks for sharing what sure is a fascinating facet of an RV's evolution.





Though overcrowded and overbuilt in the flatland, the mountainous regions of the country still offer some stunning scenery and a good playground.
Aviation is a small world, as I've now met and been entertained by James a few times on the ol'continent, last in Fall savouring some cold refreshments in either France or the UK.

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