N

Norman CYYJ

Well Known Member
Do any of you guys know of anyone with a 180hp engine in their 9. I would be interested to know what the numbers are like.(climb, speed and max altittude, speeds in the lower flight levels)
 
There's been many posts on the "180 h.p. + RV-9 performance" debate already...a quick search will bring up lots of information.

For what it's worth, many people on here will tell you that, for the sake of safety, a 160 h.p. engine should probably be considered the largest engine used in the -9. Anything bigger and you run into the chance of running too close or over Vne.

Try this for info:

http://www.vansaircraft.com/pdf/hp_limts.pdf

Best of luck :)
 
I've been told the insurance companies are siding with Van's recommendation of 160 hp max for the RV9. This would be something you might want to look into unless you just have deep pockets.
 
LifeofReiley said:
I've been told the insurance companies are siding with Van's recommendation of 160 hp max for the RV9. This would be something you might want to look into unless you just have deep pockets.
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Darrell, I have long considered going with the 360 (or now the ECI 340) due to the high D.A. enviornment I fly in here in southern Arizona. I have posted this before, that a couple of years ago at OSH I spoke with a Van's engineer, and explained to him that I was an "old, not bold" pilot who did not exceed red lines, Vne's, etc but was interested in the extra power due to the high DA's. He told me off the record that there was no reason not to go with a 360 in a -9, given those parameters.

Your post prompted me to call my insurance agent, who told me there is nothing out there that would raise the rate on a -9 with a 360. He said insurance agents are not even required to report what engine is in use when getting a quote. So I guess your point is well taken, check with your agent. This is what mine told me.
 
Not Necessary

From what I hear, this airplane has plenty of performance with 160 hp. I think I saw a post by someone in Utah the other day where they said that the -9 was perfect for the high DA's.

I wouldn't even consider it for mine. I figure Van's engineers know what they're talking about. But then again, it's experimental and you can use any source of thrust that you desire. See this LINK for more ideas along the same line as a 360.
 
IOX-340

If you want to push the envelope even more, check out the new ECI IOX-340, 20 lbs lighter than a 320, but more horsepower than a 360.

aj
 
RV-9A with 160 HP, O-320

That extra horsepower comes with a restriction other than Vne. I have the 160 HP O-320 on my RV-9A with over 200 hours on it since June 2005. The best thing about using the O-320 with a Hartzell constant speed prop is the way it gets off the ground turning a full 2650 RPM. The good thing about using the O-320 and that prop - - there are NO RPM restrictions to avoid. Get more horse power than the 160 and Hartzell will warn you of potential problems that could be hazardous to your health, without going above Vne.

I am happy with my 160 HP and my max gross weight performance. I went to OSH this year fully loaded and it was fine. The takeoff was a bit longer and the landing roll out a bit farther, but the cruising was same as always.

Jerry K. Thorne
East Ridge, TN
RV-9A N2PZ
www.n2prise.org
 
RV9 with 160hp

Another few items overlooked with 0-320 is the absence of the most recent crankshaft AD as well as the hub cracking AD of the Hartzell C/S prop. These are serious and $$$$ AD's which DO NOT APPLY making this combination more reliable from a maintenance standpoint while not sacrificing much performance IF you watch the weight while building. There are some significant pluses to this combination & I am hoping the new C/S prop will close the small gap in performance some more.

Dick DeCramer
RV6 N500DD
155 hrs on Sensenich FP
Installing Hartzell now.
1033 lb. empty with oil.
 
Insurance a serious consideration

I personally know of a local builder who went with this configuration for all the right reasons but was extremely dismayed when he called about the cost of insurance. Please, before you put any serious cash down on an engine, call a few insurance companies and find out how much flying a nonsupported factory configuration will cost you every year for as long as you fly that aircraft.

- Jim
 
Righty said:
From what I hear, this airplane has plenty of performance with 160 hp. I think I saw a post by someone in Utah the other day where they said that the -9 was perfect for the high DA's.
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Without coming up with exact numbers at the moment (it was the other guy's plane), a 9A with even just 150 HP has about two and a half times the climb performance of an older Cessna 172 with the same HP engine, and close to double the airspeed ----- in the mountainous areas of Utah.

The 160 on a 9(A) really IS perfect for the higher density altitudes. The 172 I flew the other day, felt like a "slug" in comparison. In fact, it was no comparison at all. Not even in the same ballpark!

edit: The 9A mentioned here, has a Hartzell C/S prop
 
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Good Compromise

I have 140 hours on my 9 and appreciate the cruise performance compromise verses fuel burn. Although I don?t get 30 mpg my average of 22 mpg is much better than my old '53 Pacer's 13.5mpg. My average cruise speed is 152 to 158kts at altitudes of 10,500 to 14,500 with a couple of thousand more feet thrown in for density altitude. Another 20 hp at these altitudes would still allow for plenty of airspeed margin and I have to say that is a nagging thought. Although for another 10 kts, fuel burn would increase by at least 1gph bringing mpg down to 20.5. So for what it is the 9 is a great airplane.

If I want to run at 75% at 8,000 ft I can get 167kts, but I just don?t go there.
 
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Tangent to thread: 180 hp "Super 9"

First: I agree with all those who say that 160 hp is the max and the ideal for the 9.

Second: The parallel valve 180 hp lycoming has one of the best power to weight ratios. It is very reliable and easy to come by as well. It would be cool to have a 9 non-acro, cross-country cruiser type airplane that used the 180 hp engine and could carry two adults and a few kids. Just super-size it so to speak. What could we call it. The 9.5. Since it would be between the 9 and the 10. What do you think? Is there a demand for this?
 
Rear seat

There have been builders who installed a side facing seat in the baggage area for a toddler. Just do weight and balance check,
 
RV9 w/200 hp

About 5 months ago I flew in an RV9A with 200hp modified Superior. The performance was breath taking. Like being in a GTO in a former life. We went from 4000msl to 13,500 in what seemed to be a couple of heartbeats.

DA had to be 5000 or more but with the c/s prop, this beautiful 9 pinned your butt into the seat. How long will it all last? Dunno, but the pilot is 82 years young has has been flying since forever.

My bird will have a 170hp Superior (auto gas) and when I asked for a quote, the ins company never asked what engine.
 
RV-9.5A

63scrounger said:
First: I agree with all those who say that 160 hp is the max and the ideal for the 9.

Second: The parallel valve 180 hp Lycoming has one of the best power to weight ratios. It is very reliable and easy to come by as well. It would be cool to have a 9 non-acro, cross-country cruiser type airplane that used the 180 hp engine and could carry two adults and a few kids. Just super-size it so to speak. What could we call it. The 9.5. Since it would be between the 9 and the 10. What do you think? Is there a demand for this?
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Wow... very similar thoughts to what I have been wondering lately. It would be nice to have a "Van's 9.5" - and be able to carry a third person - ie: small adult, or maybe a couple children. I also like the idea of sticking with an O-360 vs. going to the -540. I don't need 200 mph. I'd like to have 160 mph/900fpm@6,000' at gross weight.

I briefly have looked at the Zodiac CH-640 for this reason. But haven't been able to find too many flying - or associated pilot's reports on them. (oh, and they use a yoke instead of a stick).
 
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160hp 9A

We have a O-320 160hp w/80 pitch Sense, dual elctronic Lightspeed ign. We(wife and I) always cross country plan on over 8000ft 180-185mph at 7gph at 2550rpm, 325-350cht, 1250-1320egt. Our climb is 1200-1400fpm depending on how much stuff we have loaded in the back.
Hope this helps.
Frank
N821BF
240+hrs still flying with my grin
 
I just purchased an unused Mazda Renesis 4-port rotary engine for my 9A (imported from Australia for ~ $1800)- it has the same installed weight as the O-320 and is rated at 210 hp @ 7200 rpm. Most flying will be at 6000 rpm or less (180 hp). Planning to install IVO in-flight adjustable prop. I plan to use that extra HP for quick takeoffs and to improve weight margins a bit (my family are large), not for excessive speeds.

I live in Utah (like my friend Larry Adamson) and agree it is the ideal high-flying plane for the Rocky Mountains. It is important to remember that we lose ~25-30% sea level rated HP at these altitudes w/o turbocharging, so larger-than-suggested motors are probably a good idea here.
 
it has the same installed weight as the O-320 and is rated at 210 hp @ 7200 rpm.

How do you know?

Tracy's website says exactly the opposite...will be heavier than an O-320.

Please show data from whence your statement comes.
 
Jconard- I think you misquoted/misunderstood Crook.

Quoted from Tracy Crooks excellent manual "Aviators Guide to Mazda Rorary Conversion", page 109, in the section labeled Engine Weight Breakdown: "It is useful to compare it (Mazda 13b) to the Lycoming O-320. The installed weight is going to be about the same....".

The same data is also referenced in Crooks sales brochure. FWIW, I've seen similar data from several other sources that confirm or better Crooks figures.
Tracys measured engine weight, including PRSU and cooling system/coolants: 288 lbs. Firewall forward weight: 345 lbs, which added mount, exhaust manifold and muffler, and oil. That setup used 3 Mikuni carburators; Im using FI which should be a bit lighter. FWIW, I have not seen any definate weight numbers from Lycoming- they apparently do not like to post specs for comparison.

The Renesis is ~10 lbs lighter than the older 13B. The S-beam mount will also be a few pounds lighter (and probably stronger) than Tracy's 1/4" thick aluminum plate sandwiched between oil pan and engine design that uses a 4 point pre-mount and a modified Vans Dynofocal mount system. My engine just arrived from Australia this week; the B/L reported weight was 220 lbs, which including a 4 piece-METAL pallet made from 2 -18" long x 2" square steel tubing and 2- 2" angle welded together and strapped to the motor. It also included a heavy intake manifold that will be replaced with a much lighter tuned substitute optomized for sustained 5000-6000 rpm operation.

To be fair, we need to add in propeller weight too. Hydraulic C/S props tend to be heavy. Im planning to use the comosite IVO magnum in-flight adjustable propeller @ 24.2 lbs (26.7 lbs for 3-blade version). The Lycs vibrate too much for this prop and are not recommended. This prop is rated up to 700hp and has worked well on other rotary and Subaru installations.
 
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Working on my XP360- 9a

I am building a QB 9a equipped with a XP-360 180 hp and am very close to getting it flying..you know the last 10% :)

Before I made that choice I talked with a number of guys at Vans and as you expect they are hesitant to be encouraging but allways end with.. "its up to you not to exceed the airframe's limits"

Falcoln insurance was very helpfull like usuall but did tell me that I could not get rates as low as possible with the 180hp engine... That was a surprise, another surprise was that the nosedraggers are now the same price to insure as a TD due to the number of claims againt them due to them ending up on their backs more often than they should.

A friend is building one with a 320/hartzell and if I had to do it over I would go that route...I am predicting (guessing) that his plane will outperform mine in all flight regimes except wide open throttle at cruise/racing speeds..cant wait to find out!
Love to build and like to fly!
Rick
 
Regarding the previous question: I just noted that Tracy Crook reported the fire wall forward weight of this Renesis powered RV8 as 325 lbs. His 13B powered RV-4 is 345 lbs.

Tracys MEASURED FWF weight involving four O-320 instrallations was reported between 350 and 385 lbs in his book. The 4 port renesis engine is OEM rated 210 HP @ 7200 rpm, max torque 222 N/m @ 5000 rpm. The 6-port version is rated a bit higher, at 240 HP @ 8500 rpm, torque a little less, at 216 N/m at 5500 rpm.

I think it is safe to say the Renesis/13B engine's installed weight is the same or slightly less than the Lycoming O-320/ O-360's/ and O-540's. :rolleyes:
 
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cobra said:
Jconard- I think you misquoted/misunderstood Crook.

snipped
To be fair, we need to add in propeller weight too. Hydraulic C/S props tend to be heavy. Im planning to use the comosite IVO magnum in-flight adjustable propeller @ 24.2 lbs (26.7 lbs for 3-blade version). The Lycs vibrate too much for this prop and are not recommended. This prop is rated up to 700hp and has worked well on other rotary and Subaru installations.
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Mike,
It is my understanding (I could be wrong) that the IvoProp is not an ideal match to the RV airframe. Dave Atkins (Washington State) had an IvoProp on his extremely well built Mazda 13B RV6 when I met him at Tracy's fly in several years ago. He told me that the IvoProp limited his top speed to about 180 mph. He said it was like hitting a brick wall when that speed was reached. He felt that the IvoProp was engineered for slower aircraft. You might want to reconsider your choice of props or contact Dave to get his thoughts.
Charlie Kuss
 
180hp performance and insurance on a 9A

It sounds like things have changed since I chose an engine for my plane with the insurance issue. Calling to make sure that I could be insured if the 0-360 was used the answer was that as long as the engine mounted on a motor mount provided by the kit provider there was not a problem. Carefully explaining that Van was against the installation my broker again confirmed the position. This was with the Vanguard? program however and if memory serves me right excessive claims got us all cancelled effectively by not renewing us leaving less choices.

As far as performance with an 0-360 in a 9... Being one of the earlier nines (90008) I tried to put out a lot of information about how my plane performed with the 170hp 0-320 and constant speed prop so that those who followed could make adjustments to fit their needs with plenty of data. Most of this was written on the now defunct yahoo 9 groups and is now lost. It has now been about 5 years since the first 180hp 9's started flying and still there is no data to be had that is available to everybody. How about somebody with this configuration step up and share what is really happening in the air with the forbidden engine selection. We can do the math I guess with the cube root thing and figure it out, but seeing is believing for some.

An early problem with the installation of a 0-360 is probably responsable for me not using the engine. I talked with a gentleman who had been flying with a 360 and a Hartzell and he shared this information with me at the time. The Hartzell as many of you know has a restricted range where continuous operation is not possable with an 0-360. His problem was simple, if he turned the prop fast enough to exceed this range he flew to fast, and if he slowed it down below the restriction he was slower than a 0-320 160hp airplane. I knew at the time that I wanted a C/S prop and because of this went with the recommended setup, sort of. At the time the blended airfoil was not out yet and the only other choice was an MT which didn't seem like a viable choice because of cost and other unknowns to me. Now with the Whirlwinds, Catto's, MT's (more rv's flying with them), Blended airfoirl Hartzell's, the choice would be harder for me.

So how about it? How about some 180 horse guys step up and share some information with us. This question has been plaguing me since around 2001 and finally getting good information in a real flying airplane would be fantastic. I've said it before and I'll say it again. My 170hp 9A flys nowhere near the yellow! Having a plane that will not allow me the choice to fly up to the beginning of the yellow mark on the airspeed indicator in level flight makes me think that it is underpowered.

Another thing that would be interesting would be for photos to be posted here of the airspeed indicator in your 9's at 7500' with everything pushed forward along with information on engine and prop combos. I'll be surprised if there is a 160hp plane within 10 knots, or maybe 15 knots of the yellow. I'd love to see a picture like this of a 0-360 powered 9! If the overcast burns off today I'll try to post a shot to get this started.

Best,
 
Chaskuss,
Ive heard both sides of that IVOPROP comment- I would have to see some kind of "proof" that the engine is producing the full rated HP to know for sure if the prop or engine output are the limiting factor. For example, given the Subaru Torque/HP curves, the Eggy would have to be running very near its peak rpm to produce peak HP (unlike the rotary, btw), which has proven difficult to achieve with the Egg redrive ratios so far. I personally suspect that the naturally-aspirated Egg apps produce closer to 130 peak HP than 160HP at the rpms seen in real situations, tho I could easily be wrong.

I believe Tracy Crook also made similiar comments about the IVO early-on in his development program, while running his HP/rpm-limiting 3-carb setup in his 13B powered RV4; it produced a calculated peak power level around 160HP. Others have have reported better perfromance (going faster) with the Magnum prop when the power is available, so the real issue remains undecided to some extent.

I personally believe that excess HP influences climb rates more than top speeds; increasing top speed is more a function of drag reduction than increasing power. Looking at Vans charts, it is probably not a good idea to exceed the max recommended cruise speeds of ~180 mph in a 9/9A, unless the air is very smooth, for structural reasons.

In any case, I think the adjustable capabilities (improved climb rates, help slowing down, dialing in low-rpm economy cruise settings, operations at high density altitudes, etc) will outweigh any top speed limitations for my application. I'm not all that interested in running at full throttle, burning a lot of fuel, to get a few more mph anyway. I do know that the IVO is popular with the rotary canard crowd, where it gets mostly good reviews.
 
Bryan did you have a chance to get any performance data on your plane---I am interested in the results.

db
RV9a/ECI 0360/Catto Prop/James Cowl
 
db1yg said:
Bryan did you have a chance to get any performance data on your plane---I am interested in the results.

db
RV9a/ECI 0360/Catto Prop/James Cowl
Click to expand...


Sorry, I completely forgot to take the camera. I flew today and I'll give you the numbers because they are fresh in my mind. (I used the E6B function on my GPS to check the winds to give a pirep. It showed my density altitude which is why I remember it specifically.)

At a density altitude of around 7,800' with the throttle at the firewall and prop set to 2300rpm my airspeed indicator was at 140 knots INDICATED, with a true of 162 knots. This converts to 161 mph indicated and around 186 mph true. I know from experience that turning up the prop in 100 rpm increments jumps the speed by just over 2 knots per 100 rpm so if I wanted to ring its neck and spin the thing at 2700 I could get a little more. To fly with my father-in-law with his Lopresti and Knots to U infested 260 Comanche I need to run at 2500 and full throttle to get 166 knots. Basically each 100 rpm is good for around 5 horsepower on my engine.

Anyway my numbers are consistant and predictable and as you can see from what my plane was indicating on todays flight (161 mph) it was coming in 19 mph under the yellow! By putting everything in and suffering the fuel burn it will still come in at least 10 mph under the yellow.

While I've bounced back and forth on this issue several times over the last few years I think the bigger engine is most likely a better setup, at least at this point in time. Your milage may vary.

One more time... Any 180hp 9's or 9A's that can show a full throttle @ 8K' photo of their airspeed indicator. I just don't believe that it will be into the yellow in level flight.

Best,
 
old thread but never completed?

Now a couple years later and many many more RV9's - has the 160hp io-320 vs. the 180 io-360 debate been settled?
 
I didn't read through this again since doing so a couple years ago, but I have and IO360 in my 9A and know of several other people who have installed similar engines. I have not found that exceeding Vne is an issue - I only come close when going downhill. Straight and level, I get about the same numbers as everyone else (either 320 or 360 engine) - around 185-190 mph top end and around 6-8 gph depending on speed. I like the larger engine because I live at altitude and fly a lot in the mountains so the extra 20 hp just gives me a bit more confidence that I *might* get out of a sticky situation if necessary (hopefully I never have to test that).

greg
 
The recommendation of 160 HP maximum is not related to VNE (red Line), it is for the designed Vno speed or Maximum structural cruise speed. (top of green arc). Continous cruise flight at true airspeeds in the yellow arc is not a good practice.
 
3 years later, here's a picture

Well, here it is 3 years later. :eek: This shot is taken at 8,500', full throttle, and the prop set at 2,300 rpm. (Pardin the dust. :eek: Look at the true, and then look at the yellow. "How many of those naut thingys are there still in this airframe before tickling that thar yeller part that'n wer s'posed to be afearin." This is why I felt like I got laid away by being convinced to put a dinky little sissy engine in my plane. When I was deciding there was no picture like this!
oceano090112.jpg
[/URL][/IMG]
 
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rvbuilder2002 said:
Continous cruise flight at true airspeeds in the yellow arc is not a good practice.
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Scott, why is flying in the yellow a bad idea? The yellow ark (as far as I know) means damage can be caused from full deflection of control surfaces. Cruising in the yellow in smooth air is fine as long as you don't make abrupt stick or rudder input. You can fly up to VNE all day long on smooth air, just don't do a full pull on the stick, or remain in the yellow if you encounter moderate to sever turbulance. Yellow means "caution", not "don't do it", that is what VNE is for.

Airspeed Indicator Definitions

The airspeed indicator is connected to both the static ports and the pitot tube. The airspeed indicator is color-coded to help the pilot immediately recognize the important airspeeds and ranges of airspeed. The color codes are: White Arc, Green Arc, Yellow Arc, Red Radial Line, and Blue Radial Line.

White arc – The white arc is the flap operating speed. The bottom of this white arc is VS0. VS0 is the power-off stalling speed with the gear and flaps down. Going up along the airspeed indicator we come to the Green Arc. VS1 is where the white arc meets the green arc, or is commonly referred to as the bottom of green arc, or the power-off stalling speed with gear and flaps up.

Green arc – The Green Arc is the normal operating range. The very top of the green arc, is the maximum structural cruising speed, commonly known as VNO.

Yellow arc – The yellow Arc is the caution range. The aircraft should not be flown in this speed range in rough air. The Yellow Arc extends from the top of the green arc to the red line.

Red radial line – The Red Radial Line is the never-exceed speed, or VNE.

Van's spec's on the -9.... Performance Speed - Solo Weight Top Speed 197 mph
 
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Bryan Wood said:
Well, here it is 3 years later. :eek: This shot is taken at 8,500', full throttle, and the prop set at 2,300 rpm. (Pardin the dust. :eek: Look at the true, and then look at the yellow. "How many of those naut thingys are there still in this airframe before tickling that thar yeller part that'n wer s'posed to be afearin." This is why I felt like I got laid away by being convinced to put a dinky little sissy engine in my plane. When I was deciding there was no picture like this!
Click to expand...

Sorry Brian, but your example is totally pointless in the context of why a smaller engine is specified for the RV-9. If your point had any merit, you could just as well show a photo of your airplane with built with 200 HP but flying at 14,500 full throttle and 2300 RPM. The IAS would still be well within the green. How about 260 HP at 17,000........I think you get my point.

If a designer is using FAR 23 as a guide line (not required in kit airplanes but it is a good idea) when designing an airplane, then they design for a Vno speed at the engines maximum continuous power. We all know that Lycoming has set that at 75% for most of their engines. If you look at the power chart in the operators manual for your engine I think you will find that when this photo was taken you were a bit short of 75% power.
The other thing you are missing is what your IAS would be at 75% power at 2000 MSL. In the case of an RV-9 with 180 HP flying at 2000MSL at 75% power, the IAS would be well into the yellow.
 
rvbuilder2002 said:
Sorry Brian, but your example is totally pointless in the context of why a smaller engine is specified for the RV-9. If your point had any merit, you could just as well show a photo of your airplane with built with 200 HP but flying at 14,500 full throttle and 2300 RPM. The IAS would still be well within the green. How about 260 HP at 17,000........I think you get my point.

If a designer is using FAR 23 as a guide line (not required in kit airplanes but it is a good idea) when designing an airplane, then they design for a Vno speed at the engines maximum continuous power. We all know that Lycoming has set that at 75% for most of their engines. If you look at the power chart in the operators manual for your engine I think you will find that when this photo was taken you were a bit short of 75% power.
The other thing you are missing is what your IAS would be at 75% power at 2000 MSL. In the case of an RV-9 with 180 HP flying at 2000MSL at 75% power, the IAS would be well into the yellow.
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Blah, blah, blah... I could have spun he prop faster and gotten up to 75% but still couldn't have seen the yellow from there. Go back a couple of posts and read your own words. I put up a picture that supported what you stated. Then you want to argue about it? :cool: The challenge for anybody to post a picture of their airspeed indicator at 7,500' with all in has been something I've been challenging anybody arguing for a 160 hp max for years now. I'm running 170 hp and this is what it looks like. For each additional 100 rpms I get around 2 miles per hour up to around 2,600 rpm, but the fuel burn goes way up. Still, no stinkin yellow near the needle.
 
Geico266 said:
Scott, why is flying in the yellow a bad idea? The yellow ark (as far as I know) means damage can be caused from full deflection of control surfaces. Cruising in the yellow in smooth air is fine as long as you don't make abrupt stick or rudder input. You can fly up to VNE all day long on smooth air, just don't do a full pull on the stick, or remain in the yellow if you encounter moderate to sever turbulance. Yellow means "caution", not "don't do it", that is what VNE is for.

Airspeed Indicator Definitions

The airspeed indicator is connected to both the static ports and the pitot tube. The airspeed indicator is color-coded to help the pilot immediately recognize the important airspeeds and ranges of airspeed. The color codes are: White Arc, Green Arc, Yellow Arc, Red Radial Line, and Blue Radial Line.

White arc ? The white arc is the flap operating speed. The bottom of this white arc is VS0. VS0 is the power-off stalling speed with the gear and flaps down. Going up along the airspeed indicator we come to the Green Arc. VS1 is where the white arc meets the green arc, or is commonly referred to as the bottom of green arc, or the power-off stalling speed with gear and flaps up.

Green arc ? The Green Arc is the normal operating range. The very top of the green arc, is the maximum structural cruising speed, commonly known as VNO.

Yellow arc ? The yellow Arc is the caution range. The aircraft should not be flown in this speed range in rough air. The Yellow Arc extends from the top of the green arc to the red line.

Red radial line ? The Red Radial Line is the never-exceed speed, or VNE.

Van's spec's on the -9.... Performance Speed - Solo Weight Top Speed 197 mph
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The yellow arc is not related to abrupt control input, that is maneuvering speed.
The top of the green arc is Vno or max. structural cruise speed. As quoted in your post, the yellow arc range is a caution range. Avoid it in rough air.
Rough air is a very difficult thing to substantiate. I have had instances were I had been flying in smooth air for two hours and suddenly without warning got slammed on the canopy (even with tight belts) bad enough to daze me for a moment. I may have passed through the wake of a large aircraft...doesn't matter the cause, it was still rough air. If flying in the yellow arc in this typ of situation there is the potential (not guaranteed) for airframe damage. In simple terms the Vno speed is a speed at which the wing will stall under accelerated load before any damage will occur.
Avoiding flight at IAS in the yellow arc is a good idea. Regardless of the conditions at the moment you never know what is ahead ready to hit at any moment.
 
Bryan Wood said:
Blah, blah, blah... I could have spun he prop faster and gotten up to 75% but still couldn't have seen the yellow from there. Go back a couple of posts and read your own words. I put up a picture that supported what you stated. Then you want to argue about it? :cool: The challenge for anybody to post a picture of their airspeed indicator at 7,500' with all in has been something I've been challenging anybody arguing for a 160 hp max for years now. I'm running 170 hp and this is what it looks like. For each additional 100 rpms I get around 2 miles per hour up to around 2,600 rpm, but the fuel burn goes way up. Still, no stinkin yellow near the needle.
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I have no intention of arguing with you Brian...but you just don't seem to understand the difference between IAS and true airspeed.
Lets assume your power setting was 75% power when you took your photo.
Now go fly your airplane at 2000 ft AT 75% power and take a photo of it.

I bet you the IAS will be well into the yellow arc.

BTW, I am aware of what I wrote in my other post. I never mentioned any specific altitude. An RV doesn't have to be above 8000 ft to be considered to be in cruise flight.
You seem to be stuck on higher altitudes. the design issue is that at 75% power at any altitude the IAS should be in the green arc.
A 180 HP RV-9 cruising 75% power at 2000 ft will have an IAS that is in teh yellow arc range.
 
Bryan Wood said:
Well, here it is 3 years later. :eek: This shot is taken at 8,500', full throttle, and the prop set at 2,300 rpm. (Pardin the dust. :eek: Look at the true, and then look at the yellow. "How many of those naut thingys are there still in this airframe before tickling that thar yeller part that'n wer s'posed to be afearin." This is why I felt like I got laid away by being convinced to put a dinky little sissy engine in my plane. When I was deciding there was no picture like this!
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Bryan,
Just playing the Devil's Advocate here. Might be a sissy little engine but you are doing 185 TAS which is pretty respectable and at properly around 65% power. How fast do you want to cruise?? You could wind up the revs to 75% power which would have you about as close to the yellow zone as you would want to be. True, the 180 hp engine would cruise near the yellow more comfortably but isn?t 185 TAS a good compromise cruise speed as regards speed V economy? Personally, I am happy to cruise at around 165 mph TAS and only open it up to 185 mph TAS if there is a good headwind and I am in a hurry. Any faster just uses too much fuel with either engine IMHO.
I know you use oxygen so you can get above most turbulence. My cruise is below 10,000ft and often there is some turbulence in which case I would rather have a good margin before the yellow zone for both comfort and structural reasons.
Now I know you love your Hartzell C/S prop so naturally you would want a Hartzell on your 180 hp engine. The heavier engine and the heavier Hartzell for the 0-360 will increase your empty weight. Are you willing to accept this? Also you will have to do something about the excessive weight on the nose wheel which may involve adding even more weight aft.
Like you, I love my Hartzell and it is a must have item on my 9A. Others may disagree but I think the Hartzell on a 0-360 is too heavy for the 9/9A which means I accept that I am limited to the 0-320 engine. If I were using a lighter prop then maybe the 0-360 would be a consideration.
Look at it this way. Rather than thinking your 9A is underpowered, think that the structure is over strong (high yellow zone)
If I had my choice again I would still go 9A, 0-320 and Hartzell. Maybe what you really want is a 7/7A with 200hp:)

Fin
9A
 
rvbuilder2002 said:
...We all know that Lycoming has set that at 75% for most of their engines...
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Scott, I'm on your side in this stuff, but for the engines we are talking about, normally aspirated O-320s and O-360s I can't find anything from Lycoming that limits the engines to 75% continuous power. I believe they are rated at 100% continuous power. Please advise me if I am wrong. I certainly can't find anything about a 75% power limitation.
 
rvbuilder2002 said:
I have no intention of arguing with you Brian...but you just don't seem to understand the difference between IAS and true airspeed.
Lets assume your power setting was 75% power when you took your photo.
Now go fly your airplane at 2000 ft AT 75% power and take a photo of it.

I bet you the IAS will be well into the yellow arc.

BTW, I am aware of what I wrote in my other post. I never mentioned any specific altitude. An RV doesn't have to be above 8000 ft to be considered to be in cruise flight.
You seem to be stuck on higher altitudes. the design issue is that at 75% power at any altitude the IAS should be in the green arc.
A 180 HP RV-9 cruising 75% power at 2000 ft will have an IAS that is in teh yellow arc range.
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We're going to have to agree to disagree. I don't want to argue with you either, but you should know just how condesending your response to the picture was. It certainly had the potential to encite rage.

As for indicated vs. true, I understand the difference just fine. I just went back and re-read my post where I typed, "Look at the true, then look at the yellow." I see where you got confused with what I had written because it was so general that it appears to be nonsense if a person didn't know the direction that this debate always seems to go. Somewhere over the last couple of years when discussing this topic the reasoning for a smaller engine would change to high true airspeeds and flutter instead of simply considering indicated airspeed. This came about after Ken Krueger penned an article about putting a turbo on the RV-10 and the high true airspeeds potentially causing flutter. That arguement migrated over to the nines somehow and was has been the direction this topic goes once the inablility to reach the yellow starts to get attention and the argument for a small engine begins to weaken. My statement was the short version of attempting to cut that off at the pass. I've been stating my airspeed in this condensed manner for years when discussing engine size and incorrectly assumed that others understood the direction this debate always goes. So in short, in that one sentence both arguments against the bigger engine were squashed, or at least a feeble attempt was made at addressing both arguements. With that said...

If you look at what my airspeed is indicating it is 16 mph under the yellow. The OAT is set to the alt at the top of the airspeed indicator showing true on the white rotating card. We could do the math manually, but what's the point. While my plane meets the published specs or better , it lacks the ability to get to the yellow unless in a 200 fpm decent of so in cruise. As for going all in down low, well that is what a throttle is for. I wish somebody would have been up front and told me that the concern was whether or not the end user had the common sense to not fly the wings off when down low. A lot has come out since I started my build. My plane is kit number 8 and believe me all I got were stern warnings about how a 180 hp engine would just simply be to fast, but nothing was forthcoming that my plane would have a 16 mph safety margin before getting to the yellow safety margin. The true airspeed also passes the flutter argument that came along later on and appears to have room for more "Pretty Horses" under the hood. I always heard that a picture is worth a thousand words, but that isn't true at all. It seems a thousand words were needed to back up what the picture was showing.
 
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Back when the -9 was introduced, I was very interested in it and in fact built the tail kit. I had an 0360 engine for it.

Then I talked with Van at OSH, you know, the guy whose company designed, flight tested and is selling the kit, and he said go ahead and use the 0360 but plan on flying around with partial throttle unless you want to exceed the design parameters of the airplane. He would not give his blessing to use it.
 
Bryan Wood said:
We're going to have to agree to disagree. I don't want to argue with you either, but you should know just how condesending your response to the picture was. It certainly had the potential to encite rage.

While my plane meets the published specs or better , it lacks the ability to get to the yellow unless in a 200 fpm decent of so in cruise. As for going all in down low, well that is what a throttle is for.
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Brian,
I want to apologize if that is the effect my post had. I am not always good with words. That is not the intent I had, I am sorry. I also hadn't noticed previously that you represent your airplane as having 170 HP, not 180. You have always seemed to be a big proponent for using 180 HP in an RV-9 so I made an incorrect assumption.

The point I was trying to make was that showing an IAS at 8500 feet that is in the green arc is not relevant to the reason the RV-9 is recommended for engines only up to 160 HP. A 180 HP RV-9 at 75% power at 8500 ft probably would be about 7-8 mph IAS short of the yellow arc, but at 75% power at 2500 ft it would have an IAS that was well into the yellow arc. Please note that at 2500 feet, "all in" is not 75% power, it is well over that.

That is the reason the RV-9 is only approved for up to a 160 HP engine.
 
n5lp said:
Scott, I'm on your side in this stuff, but for the engines we are talking about, normally aspirated O-320s and O-360s I can't find anything from Lycoming that limits the engines to 75% continuous power. I believe they are rated at 100% continuous power. Please advise me if I am wrong. I certainly can't find anything about a 75% power limitation.
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Your right Larry. I did a quick look in some of the documentation I have at home and even the type certificate data sheets list max HP and RPM as continuous.
I didn't remember that, thanks for pointing it out.
That would make the RV-9 160 HP recommended limit even more relevant.
 
rvbuilder2002 said:
Brian,
I want to apologize if that is the effect my post had. I am not always good with words. That is not the intent I had, I am sorry. I also hadn't noticed previously that you represent your airplane as having 170 HP, not 180. You have always seemed to be a big proponent for using 180 HP in an RV-9 so I made an incorrect assumption.

The point I was trying to make was that showing an IAS at 8500 feet that is in the green arc is not relevant to the reason the RV-9 is recommended for engines only up to 160 HP. A 180 HP RV-9 at 75% power at 8500 ft probably would be about 7-8 mph IAS short of the yellow arc, but at 75% power at 2500 ft it would have an IAS that was well into the yellow arc. Please note that at 2500 feet, "all in" is not 75% power, it is well over that.

That is the reason the RV-9 is only approved for up to a 160 HP engine.
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No worries, accepted and back at you. If the truth be told I've flip flopped on the engine debate over the years. I guess it is the grass is always greener thing playing out.
 
n5lp said:
Scott, I'm on your side in this stuff, but for the engines we are talking about, normally aspirated O-320s and O-360s I can't find anything from Lycoming that limits the engines to 75% continuous power. I believe they are rated at 100% continuous power. Please advise me if I am wrong. I certainly can't find anything about a 75% power limitation.
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I think you are correct that they are rated at 100% continuous, however this is from Lycoming for normally aspirated engines:

For maximum service life, maintain the following recommended limits for continuous cruise operation:
a. Engine power setting ? 65% of rated or less.
b. Cylinder head temperatures ? 400˚ F. or below.
c. Oil temperature ? 165˚ F. ? 220˚ F.

Fin
9A
 
smithhb said:
Not to beat a dead horse here but this is not true for my beast. I guess I had better get those wheel fairings finished....
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I'm not sure what you have installed for fairings right now, but a full set is good for about 15 MPH at cruise power settings.
 
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