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Debating an RV-9 purchase

Lemos

Active Member
I am debating the purchase of an RV-9. I really want to build, but I am just not sure yet that I have the capability or tenacity. I am thinking about buying a pre-built airplane and getting the hang of maintaining an airplane before I take on the prospect of building an airplane.

So I went to look at an RV-9 today. Beautiful airplane. Dynon Skyview HDX panel, ADS-B IN and OUT, nice interior, beautiful paint. We decided to go for a demo ride, and all that I can say is W-O-W!!! This aircraft is really something! The aircraft has a Catto 3 blade prop with a Lycoming IO-360 motor.

During the demo flight, we went to 7500' (she sure climbs like a homesick angel!) and let her rip. 2600 RPM and 151 knots true, burning 10.5 gallons per hour. I was a little surprised by the fuel flow. Since the airplane holds 36 (or is it 38 gallons?) it really needs to be on the ground after 3 hours, and even then will only have around 4-6 gallons remaining. That's a pretty short legged airplane. Do these numbers sound correct? What are RV-9 pilots finding themselves doing, limiting to 2.5 hour legs or so? I thought I had heard of folks flying 4+ hours.

So here I sit, wanting the airplane BAD. If I felt better about the fuel limitations, I probably would have pulled the trigger and put the airplane into pre-buy. But man, that airplane is thirsty, and I am afraid I may feel like it's short on fuel. Can I add more fuel capacity, realistically?
 
I imagine some of the other RV-9 owners will post and mention that they get similar TAS at far lower fuel flow.

Makes me wonder if the owner is timid with their leaning.
 
Its also not designed for a 360, although people do it despite being warned not to.

At 7500 feet fuel flow should be less than 10 gph.

A properly set up and leaned rv 9 will burn closer to 7 gph, which makes a big difference. 4 hours should be a very easy number to achieve with comfortable reserves.
 
150 ktas, 10K altitude, 5.7 gph

I have completed a 600 nm trip plus 3 local flights and still had 10 gal in the tanks.
 
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Its also not designed for a 360, although people do it despite being warned not to.

At 7500 feet fuel flow should be less than 10 gph.

A properly set up and leaned rv 9 will burn closer to 7 gph, which makes a big difference. 4 hours should be a very easy number to achieve with comfortable reserves.

The pilot just pulled back the mixture until the engine ran rough, and then pushed it back in again. It has a Dynon instrumentation system, so I thought that you could lean with EGT. I am barely current again, so leaning is something that I need to freshen up on.

Is there any risk of the engine being damaged by the poor leaning technique? Is there something that I should check on a pre-purchase? Or is it only a case of wasted fuel?
 
I just got done making a big trip from Kentucky to Wisconsin to Colorado and back.

The 9 likes to be up a bit higher to get the fuel burn and cruise speed up. On the way to Wisconsin I was flying formation with 2 rv8's down low due to cloud layer. They were throttled back burning around 7 gph, I was 2500 rpm burning 13. We were racing a big storm so time was important.

After Wisconsin I left solo and flew between 8500 and 13,500 for the rest of the trip and was seeing TAS around 140 range, fuel burn 7.5 leaning some but probably could do some more.

At 7.5 4 hours is not a problem for the plane. For the bladder, backside and tummy 4 hours can be more than enough.
 
Leaning

Al,

Regarding your questions on leaning, you should read these articles:

https://www.avweb.com/features/avwe...-perch-63where-should-i-run-my-engine-part-1/
https://www.avweb.com/features/avwe...where-should-i-run-my-enginepart-2-the-climb/
https://www.avweb.com/features/avwe...-65where-should-i-run-my-enginepart-3-cruise/
https://www.avweb.com/features/avwe...66where-should-i-run-my-enginepart-4-descent/

https://www.avweb.com/features_old/pelicans-perch-18mixture-magic/

Although I drive a 7 and not a 9, my aircraft will cruise at 163KTAS at 8500' burning 7.8GPH about 50°F LOP with constant speed Hartzell prop on a 8.5:1 IO-360M1B (180hp) with dual PMAGs. The same setup in a 9 should be able to do about 3kts less for the same fuel burn. Your consumption numbers do seem a little on the high side, but with the climb optimized 3 blade FP prop, you will consume a little more in cruise. These aircraft have amazingly good range if flown LOP when in cruise.

Regards,

Tom.
 
Unless the airplane is really out of shape, I wouldn't get too caught up on the fuel flow. That number is high by quite a bit and I would bet is easily resolved in the first week of ownership. At that speed though, the prop sounds a little more climb than I would prefer. Also resolvable.
 
Unless the airplane is really out of shape, I wouldn't get too caught up on the fuel flow. That number is high by quite a bit and I would bet is easily resolved in the first week of ownership. At that speed though, the prop sounds a little more climb than I would prefer. Also resolvable.

When you say easily resolved, I assume that you mean by properly leaning?
 
RV-9A

Well we will try this again. Wrong photo, wrong way to attach it. Anyway, I have an -A not a taildragger which is cleaner than the noseddragger, but still am performing much better than the OPs demo flight. Pics are below showing the plane at 145 IAS (178 TAS) burning 6.6 Gal/Hr at LOP about 25F, I could have gotten fuel rate to 6.0 but given up some speed by running more LOP.
Ed
9ex_dZRg-xf982sNfUjosl3HNTYbKVm4y_vC7SOzG0f_s6TGT_5_6gtYEEwJQuRzdVIPqF_OZEgyvRHbwwi5GHT6HYEc5oE4yB5cGGFphFDap7hVn5bstPhNMAsue092KfatfHsM139LvLRS8GR_07pCc3aMyEtBM3FdYXVaQtcBp9WkiwvxOlygJrKh1aEAaIcn0oWtEVheW2Wa0cN1xIPRUqvM6YhqU2Uecgd9CkdrUhban22O84YHM2u_yCtR84wetggsTC-aX6vjRztjmvbn7XQNl08CPMqSLyULaqTOb8RKdqNQrhVLUPqqAo5nawUBJ4UHl8ZT_7YiqP7LutIoiNxzCZ3wmgSZ48hp8y2f5E0SNIePYphoYIebT8uTihmaC7Jmo9mmiVNdJ0fOyCqQ-RTzin0Qyb8V330XuD5LqZwAnZ0v_qrKfWODGny7vnQw77Muc4Xd6iCiiUupg3B4W2OhE_6SOqFwckjEl4z2-nC2zbsEmhjhmoerh-FPQ_Gdqvw8hwKIsc-D7G7D6LMBhtdi5RmUp4AeuORWcor8nk1wxAsGmL0zsqS4yL9r0Sp6F3IalJusbEMfaPNWCaJDF2ahqj0zmcUOsyILR8EgqEJa97X66Y5xJzuBg_TnFI-OD9Kiu72E9m4fdIGXg239tbWrDweaTN4hqYs1E738QvVUHsqREKYELR-XIg=w772-h579


SXr9wrS0wlv8y_zjY9wSrBO2kFxOl7CAG0xshqXkR1juMwuqL2LZIK_q0XIyKV6i_VoMWdKJobCUY-uZHtjPEkedeVqhR0L-huTy4QMeh3GlFg4SlZUyNJ5-it9AygpGv5m4eFmX-IQcoOCnzPi0NjGWQQ3JM7qZpPdpo2-QSGJpatSTTOZXA7mlsFcnKYreNGg4Ivkg5Jm_XlV6l0e5Ew4gn4tuL7PJDjEu67O_TCHXlPNg9uK_vO_Pr6BNx921XjoApgUm44ymuUVIDzGK-qgQwEiVrYQaIAc-Ci31yoiC_FabfTp33faGZswLEmgLp6Iwej5XK970_UHedw5GqWOYZSXfOKSh4iNPW6B5eYq_I1KCXE-UNHmx1NVWD66acQEd2j98dotoYWDXBmvPCbRXb2tDgI0eq8DQhPH5F1S7-Xx0YNSzhfNvRSSXw9KSnfndlt31x8ZVZXEsQWq7GQN5VeRBDYwWY0fqXvo5GFvUXuiDHz3OfWnAVMkiBOMwrwIUejI6gfFi_A1ZReAiPZSZ2XU2JfEL5l-gpLZdXJ3jtYrl1ehuM_-lHEIj39H7RcViAd_RFsrOVjV_PKhng67O_IWX_VM9EE-pCaw9mEegsV4wURbImmkBumvaQ2dapLVevmRVhfULAiFOb2Qp4s6zw5t3VUqh90M5KQtTlKwSpWYaYNaueC1XJ_D-iw=w435-h579
 
178 TAS at 6.6 GPH is way at least 25 kits better than I see on that fuel flow in a 7A with Catto fixed pitch and IO360 and no exceptional build quality. Is this reproducible at level flight in smooth air and confirmed by ground speed in a box pattern? If so, did you streamline in an unusual way?
 
178 TAS at 6.6 GPH is way at least 25 kits better than I see on that fuel flow in a 7A with Catto fixed pitch and IO360 and no exceptional build quality. Is this reproducible at level flight in smooth air and confirmed by ground speed in a box pattern? If so, did you streamline in an unusual way?

edclee is talking MPH, and it appears you're talking in KTS.

178 MPH = 155 KTS. So that explains 23 of the 25 knots that you are saying you're missing.
 
RV-9 partially complete

I know of an RV-9 that is 75% complete (guessing on that %) here in Gallatin, Tn. If you may be interested PM me.
 
9A

Several flights I’ve been in a buddy’s 9A with IO-320, Hartzell CS, 1 Slick-1 ElectroAir and Lean of Peak at 7-8000’ cruise altitude this plane will consistently do about 155 kts TAS burning around 8 gph or less. Higher would yield more efficiency.

Don Broussard
RV9 Rebuild in Progress
57 Pacer
 
178 TAS at 6.6 GPH is way at least 25 kits better than I see on that fuel flow in a 7A with Catto fixed pitch and IO360 and no exceptional build quality. Is this reproducible at level flight in smooth air and confirmed by ground speed in a box pattern? If so, did you streamline in an unusual way?

That is not Knots, but MPH. The -9 will outdo a 7 at high altitudes where the Roncz airfoil works.
Ed
 
During the demo flight, we went to 7500' (she sure climbs like a homesick angel!) and let her rip. 2600 RPM and 151 knots true, burning 10.5 gallons per hour. I was a little surprised by the fuel flow. Since the airplane holds 36 (or is it 38 gallons?) it really needs to be on the ground after 3 hours, and even then will only have around 4-6 gallons remaining. That's a pretty short legged airplane. Do these numbers sound correct? What are RV-9 pilots finding themselves doing, limiting to 2.5 hour legs or so? I thought I had heard of folks flying 4+ hours.


I flew my RV-9A this morning. I have an ECI IO-360 in it, and also have a Catto three blade. So aside from being a 9A rather than the 9 that you flew, I expect that my data is likely quite similar to what you'd see in a 9.

I was at 5,500' and leaned per the Lycoming recommended 50° ROP..
75% power, I was burning around 9.0 GPH.
65% power, I was burning around 8.2 GPH.
55% power, I was burning around 7.4 GPH.

Too short of a flight today to get better data, but I think at 9,500' - 11,500' in an RV-9 airframe, you'd find a nice balance of speed and fuel consumption.
 
This is an IO360 with a constant speed prop, but a good Catto pitched for cruise should give the same numbers, possibly a bit better. The speeds are all in knots.
 

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And for really good cross-country performance - take it up higher. The 9 wing loves higher altitude.
 

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Greg,

Any reason why you set the Va (Manuevering Speed) bug so much higher than Van's published speed of 103 KIAS (118 MPH IAS)?

Heh... nope... just never changed it from the default. I watch the airspeed for Vne pretty closely on descents, but never bothered with the Va/Vy/Vx bugs on the tape. Gives me one more item to tweak on the airplane. :D
 
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Greg,
Impressive screen shots! In particular the NM/Gal. Love the Roncz airfoil.

Jim

Yes but that's mostly an artifact of the tailwind in that shot.

Running WOTLOP in the 6k-10k range, I generally see low 160's KTAS at 20-21 nm/gal referenced to still air. If I climb into the mid-teens I'll see high 150's for speed and regularly get 25 nm/gal. If I pull the speed back to 135KTAS at altitude, I can get 28-29 nm/gal.

Handy stuff to know for long-distance flights. I'm doing some econ-cruise data gathering now for a round-the-world trip later. Some big chunks of ocean out there that need to get covered, ya know.

But back to the OP question - the fuel efficiency of the airplane is terrific, more so if you operate lean of peak. I have extended range tanks (67 gallons in the wings) so I'm cheating on the range - I can run 1200nm with IFR reserves and regularly do 6-7 hour flights.
 
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