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(N2O) Nitrous Oxide and Lycomings

"We are ALL test pilots"

I spoke with a winning RV-8 racer at Reno about his extremes of VNE at Reno, as well as the doubling of horsepower with nitrous. He grinned and said, "We are all test pilots here. And we know it. You want to win?"
 
Fun thread to catch up on. Sorry to not have been posting much lately...heads-down in preparation, mods, testing, evaluating, re-testing, lather...rinse...repeat. Class duties took more bandwidth than usual this year too (long story about external issues). 'Nuf said ;)

I did juice up this year, after swearing for the past couple years that I would not...having opted towards drag reduction efforts and the development/building of Steve's new wings (we WILL get there!). So what changed?

In April, we had several new Lancair and Glasair pilots sign up for Sport Class membership and PRS (Pylon Racing Seminar). There was a brief concern that RARA might need to reduce the schedule to allow everything to fit in the waiver period, and Sport Medallion was seen as low-hanging fruit. While I went to the mat to fight for that, a few of us in the "Metal Mafia" evaluated our prospects, and did not like what we saw...which was the prospect of it taking over 260 mph to make the field, if a heat was cut and all the prospective newbies came to race. To get into the Silver heat, after several dropped from PRS, others dropped from racing altogether (insurance costs and other reasons), and a win on keeping the Medallion heat, was not something I would have forecast in April and May. Thus began the quest for speed. Turbo? Super? Chemical? Hmmmm.

One of the MM fellas (Olivier, in his Epsilon...our lone Experimental Exhibition plane), found a wet N2O system built by Don Rivera at Airflow Performance. It's a very nicely packaged module with N20, Fuel, and Purge solenoids, and is set up for a tidy installation, with the capability to change orifices for a 50, 100 or 150 HP shot (and there may be capacity for other options). Given Don's history of excellence, I called, talked it over with him, and purchased the system. My job was to make the installation and plumbing come together (I now have a small hose and fittings department in my hangar ;)), and to test it to be sure I could run the system safely for 10 minutes and keep my engine within limits.

I want to thank Don very, very much for the multiple phone calls and the crazy awesome support in sending parts on short notice. He even fabricated a spacer block for me overnight, just before going on vacation, as I was installing and finding fitment issues. Don is just a great guy!

A quick reply to the comment about "we're all test pilots here" (which I know is just a quote): The testing is done prior to Reno, and not at Reno on the race course. We may be pushing the edge of the envelope, but our philosophy is that we better not be doing something on the race course, that we haven't done in the plane before. A well prepared aircraft and pilot are what wins at Reno...not a caution to the wind, throw it all forward and see what happens approach. I tested extensively with the 50 HP shot, knew I could go the full 10 minutes and not run out of nitrous, and knew how much water I needed to carry to keep the motor in limits. We worked on timing adjustments (with great help from Mike K at ElectroAir), and leaning adjustments (using an Air Fuel Ratio gauge)...all following long, collaborative discussions with other racers, some using nitrous, and some using turbochargers or superchargers. We all help each other out quite a bit. Though we might not share our flying secrets completely, when it comes to helping each other prepare a safe race plane, we do collaborate a lot.

With that in mind, we spent a significant amount of time during the test phase, playing with timing and leaning, and adding and adjusting water spray on the cylinders. That tweaking continued during race week to get the temps on the cylinders more balanced (small adjustments, not major changes...so I hope that does not sound in opposition to the previous paragraph). We were really close, and were all looking forward to Sunday, as we really felt dialed in. If not for a 20+ year old fuel pressure transducer...ugh. But I couldn't take off and go around Peavine and into the chute with a suspect indication like that. It hurt...but it was the right thing to do. The really right thing to do now is to upgrade from the old VM-1000 to the Dynon that I've been talking about for way too long. I really wanted to chase that SX-300, and keep up the "Passin' Glass" world tour that Neil Wischer (Sport 888) coined this year! :D Lesson learned the hard way :(.

The pre-race week and race week were busy and fun. We flew the practice and prequalifying periods with 3 different sets of wingtips this year. All had been fully tested prior to the course work, but final performance can't be measured anywhere but on the pylons. Bob Kuykendall and Steve Smith's HP Aircraft tips were the fastest, and we qualified with them. With the 50HP shot running, and the HP tips, our 262 mph run for two laps could have been better, but not because of the plane...it was the pilot. I ran a slightly soft and high first lap, trying to get things wound up a bit, and then caught a Glasair III on the second lap. He did a great job staying low and tight during the pass, but I never found my sweet spot line (my story, stickin too it...but my stick and rudder too). The 263 average lap speed on Saturday, and fastest lap of 267 that day, were more gratifying...especially since it was so windy and bumpy...one of the more physical hops I've had outside of ACM, Aerobatics or Jet Reno Racing. And as the only taildragger in that heat, it was game on until it was parked! Whew!

With regards to the discussion of Vne...it is a topic taken very seriously. What is the Vne of a racing Super Legacy, Super Glasair, Rocket or RV? "It depends" sounds like a trite answer, but it really does apply. The fast glass crowd has done extensive strengthening to the fuselage and tail...extensive extra carbon wraps, and other measures. My Super Six was built ground up with similar strength measures to the Rocket line...somewhat evidenced in the 1250+ pound empty weight. Vne is listed as 275 mph. Thicker skin in areas, thicker stringers between the longerons, significant bracing in specific locations, clipped wings like the HRII. I added a modified RV-8 VS and Rudder, with strengthening measures added in. Future plans call for more mods to the HS/Elevator and the VS/Rudder. Vne not taken lightly here. Each builder/racer must take their own approach to pressing the limits safely, and I do believe our class safety culture makes this a high priority.

As far as Metal Mafia records go, Bill Beaton (HRII), Todd Rudberg (RV-8), Neil Wischer (RV-8), Dan West (RV-8SC), Lee Ulrich (RV-7TC), Mark Frederick (F1) and I have had some fun along the way, and our competitive juices should keep the competition alive and well.

My goal several years back was to work to the point where I could fly a level lap at my Vne. Bill, Todd and Neil raised the bar on that a bit, when they qualified at the following speeds:

276.899 (Todd's 2019, and current Metal Mafia record, qual)
275.613 (Bill's 2016 281.762 corrected for current course measurement)
271.954 (Neil's qual this year, and fastest of the MM this year)

Fastest Average speed for an entire race sits as follows (Bill's speed corrected to current course measurement):

Bill: 272.417 (2016)
Neil: 268.016 (2019)
Todd: 265.446 (2019)
Me: 263.838 (2021)


I know Neil is gunning for Todd's Fastest RV-8 title, and Bill's numbers are in my crosshairs, especially if they can be run safely for an entire race. Lot's of work required to get there! Fun stuff! :D

Cheers,
Bob
 
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Not Quite

80+" of manifold pressure - for TBO's measured in minutes, not hours! :D

This is not quite true. AFAIK, all of the top 3 Sport Gold contenders (all running 90+") flew their multi-hour flights home on their race engines!

Skylor
RV-8, Sport 80
 
Nasty,

Thanks for the updates.

Need pics of the new tips.

I like the PASSING GLASS.

Did a little passing gas in my days.:D

Boomer
 
Here is a picture of Bob Mills' Rocket 6 on Saturday. You can see that there was mountain wave working everywhere, all nicely marked out by streets of lenticulars. I could have done lap races from Susanville to Bishop all day long at FL240 in my glider. But it made for a very rough day on the pylons, and a stiff 45 degree cross wind for landing. Several races and performances were cancelled for the day.
race49 on a wave day.jpg
I didn't get a picture of the new wing tips installed, but Bob Kuykendall did. We are working with Doug to set up advertising, so we will start a new thread talking about the new tips soon.
 
This is not quite true. AFAIK, all of the top 3 Sport Gold contenders (all running 90+") flew their multi-hour flights home on their race engines!

Skylor
RV-8, Sport 80

Andy and Jim are back home, and Jeff left his plane in Reno to fly his P-51 back to Chino (I know, rough, eh! ;)). None of them will tell you what they really run for MP...but I know at least one is over 100. Andy gets 60 minutes at race power on that prop...from the manufacturer. It takes a few races to get there in 8 minute shots. New prop, new motor each year.

As they say..."speed costs...how fast do you want to go?"


Nasty,

Thanks for the updates.

Need pics of the new tips.

I like the PASSING GLASS.

Did a little passing gas in my days.:D

Boomer

I seem to recall that Boomer! :eek::p


Here is a picture of Bob Mills' Rocket 6 on Saturday. You can see that there was mountain wave working everywhere, all nicely marked out by streets of lenticulars. I could have done lap races from Susanville to Bishop all day long at FL240 in my glider. But it made for a very rough day on the pylons, and a stiff 45 degree cross wind for landing. Several races and performances were cancelled for the day.
View attachment 16166
I didn't get a picture of the new wing tips installed, but Bob Kuykendall did. We are working with Doug to set up advertising, so we will start a new thread talking about the new tips soon.

Here are a few pics...none that good, but it provides a little idea of them. Smooth curved front, with a tapering trailing edge. The bottom photo makes the left wing look flat, due to the way the gray tape stands out (we had more red tape delivered that day!). The tips felt quite good in the turns. We were concerned about bleed rates with my clipped wings, but I think they did well.

iT3PgeDkc4kYPzPk4RxbelHBn87uLzpTYI53H8OMF6leVLPIdaMU777sm-GIUogs_U2JBEE71XltCDVQKg=w902-h440


abJkJe5AihAHeKJZB8_TVuPx1k_U8QwfPfoQ1-sKx2HA6K0KavZ_RItCri8rObV0i5yvKik-dP7wkKBb8g=w460-h440


c8iNeTnVIuMNu6teqb9QPhjf_uRH-XGx7I35h8GOJ5pGe8CFpJptVc3Jvfq6FS5AJnpc2x0zmOOOJ6MeRA=w614-h440


Cheers,
Bob
 
Thank you Bob Mills

For your posts today, great reading! Looking forward to next year.
 
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