Ben E.

Ovation Speeds

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Based on some searches it seems like you have to run the Ovation at lower power settings if you want to make TBO.  What would you guys say is the highest power setting and resultant TAS you can use in the Ovation and still hope to make TBO?  I'm trying to figure out the practical speed advantage of the Ovation over the J...

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The original Ovation had a 2500 rpm red line and as such was derated to 280hp. The newer ones are 2700 and 310 hp. I would think of that rpm range as take off power. I run 24/24 as my top cruise setting and run LOP and I'm about to exceed TBO.... for what it's worth....

I don't really think of that as much of a reduced setting...

I flight plan 175kts at 13gph. FIKI bird so slower. Around 5-6k feet usually....


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Negative captain...

TBO will be made in Ovations regularly.

I think you may be referring to having a Top OH done.

Depending on how hard you run the IO550 can result in how or when you will need a set of cylinders.

It is possible to maintain control of CHTs to save the 2AMU X6 expense.  Cruising around LOP above 10k' CHTs are well below common thought limits.

As PIC you get to choose.

How Does that sound?

Best regards,

-a-

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Prob the best advice for engine longevity is a good engine monitor and understand how to use it...

121b1e0061c1855b7ca700795121635b.jpg


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The Ovation 2 two blade prop was the most efficient prop and it was the one used to set the Mooney advertising 192kts with the 2500 rpm 280 hp engine.  Later the 3 blade top prop and 2700 rpm 310 hp was advertising 197kts.  

The 310hp vs the 200hp really makes the difference in runway usage and climb rate. As I recall a ferry pilot noted a 800 ft/m climb through ~8k with a 3900# TO weight...that to me is very impressive. 

Speed wise I normally see 165-175 LOP at 11-13 ish gph. I normally fly from 5-15k depending on winds. I dropped the engine at 2500hrs because it was a good time schedule wise but I would have had no problem pushing another 3-500 out of it. 

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Based upon several hundred hours of cross country '78 J with a mid-time io360 with two blade and '99 O with low time io550 and three blade, flying around 10k and thinking it's flying the engine 'easy' (around 2400 rpm):

J - 155kts, flowing 8 to 10 gph

O - 175kts, flowing 12 to 15 gph

So not that much of a cruise speed differential.  Climb and comfort are wholly separate judgements.  The io550 likes fuel and will eat it if you're generous, but doesn't seem to demand it (up to a point). 

GAMIs on both, O cylinder temps are hard to keep up at those altitudes, while the J occasionally needed some cowl flap action in the summer.

 

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Based upon several hundred hours of cross country '78 J with a mid-time io360 with two blade and '99 O with low time io550 and three blade, flying around 10k and thinking it's flying the engine 'easy' (around 2400 rpm):
J - 155kts, flowing 8 to 10 gph
O - 175kts, flowing 12 to 15 gph
So not that much of a cruise speed differential.  Climb and comfort are wholly separate judgements.  The io550 likes fuel and will eat it if you're generous, but doesn't seem to demand it (up to a point). 
GAMIs on both, O cylinder temps are hard to keep up at those altitudes, while the J occasionally needed some cowl flap action in the summer.
 


20 knots is 20 knots!


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12 hours ago, Ben E. said:

Based on some searches it seems like you have to run the Ovation at lower power settings if you want to make TBO.  What would you guys say is the highest power setting and resultant TAS you can use in the Ovation and still hope to make TBO?  I'm trying to figure out the practical speed advantage of the Ovation over the J...

Ben, low power settings to make TBO?  Not correct.  Also, the Ovation and the "J" are two completely different ships in many ways, but for starters, I'll answer your TBO-related question from my specific ship's configuration (IO550-N8B, 310BHP, 2700RPM, Acclaim Type-S prop (Hartzell.....F7498)), Usable load = 1004lbs, TKS-equipped).

* Cruise full-throttle (taking advantage of all available power from a tuned-induction engine) above ~8000MSL, 2550RPM

* If below ~8000, reduce to 23" and 2550RPM

Typically, I see 175-182TAS, burning 14.8 - 15.0GPH LOP at 8000.  There's no appreciable benefit of pulling back an IO550G (2500RPM) below 2500 in cruise.  In the "N" engine, 2550RPM is the best target.  These two benchmarks were established, tested, and validated mainly by Minnis Aviation (Bob M. was a former manager at then-TCM, and a co-designer of the IO550 engine platform.  He was a developer of the 310HP STC...more threads on this if you search for him on this forum).

I personally know of four Ovations that have gone to between 2000 and 2200+ hours using these operating parameters (two were at least 2200+ hours, which my IA replaced).  In all cases, the engines were still demonstrating good overall operating health, but the owners decided that tempting fate beyond the 2200-hour mark was something they couldn't live with and opted for a rebuild or OH, so they were voluntarily pulled from service.  Both engines were operated LOP for the large majority of their lifecycles.   Due in part to a lot of this data, Continental increased the TBO on some of its engines, including the IO550, from 2000 to 2200 hours.

Aside from these examples, there simply aren't a high number of Ovations that have close to TBO hours on them.  Some, but not many.  I do know of several Ovations who operate outside of these parameters who ended up replacing engines much earlier.  Hope this helps...

Steve

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My results are similar to what you've already read here. I cruise in the 8K to 10K range generally, at WOT and 2450 to 2500 RPM (slightly less RPM if I can take advantage of tail winds). I run slightly LOP at these settings and generally get about 175 knots at 13.5 GPH. I basically lean to keep my hottest cylinder at 350dF or less, which makes my coolest cylinder usually below 300. (I have a fairly wide distribution because of the alternator in front of #5...haven't done the pixie hole maneuver yet. Search for that if you're interested.)

In practical terms, a trip I make quite often is between Atlanta (PDK) and Amelia Island FL (FHB). In my J, it would routinely take about 2 hours, including routing around or over Hartsfield. In the O that is 1.5 hours, so even on a short trip like this I save a half hour. Doesn't seem like much, but it adds up. And the climb capability, comfort and style of the Ovation are also nice benefits. Don't get me wrong...I loved my J and it's a fine airplane, but I have to admit I like my Ovation even that much more.

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Thanks for all the replies guys.  Please excuse me if the question sounds silly.  I only have about 2 hours in complex planes and engine management wasn't stressed.  Yes, I do mean make it to TBO without a top OH.  So it seems that it's not reduced a reduced power setting that allows the engine to make TBO--based on the attached power settings table from the POH you guys seem to be running at 75% power when possible based on altitude, otherwise 65%.  Rather, LOP operations seem to be the common theme.  When you guys say if you run the engine hard you may be looking at a new set of cylinders, are you talking about ROP operations, or is it something else?  Also, shouldn't operating at ROP provide more fuel that will cool the cylinders down?

M20R Cruise Power Settings and Fuel Flows (Economy Cruise).PNG

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The common advice is keep your cyl from overheating, get the oil temp up when you do start to get the moisture boiled off, preheat below 50f and use single weight oil (and because of this preheat religiously) so that oil will thicken and protect engine between flights, and don't let the plane sit too long without running. Oh and good engine monitor with Gami injectors...

Oh and read and understand this: https://www.jpinstruments.com/wp-content/uploads/2013/05/Mike-Bush-Red-BoxRed-Fin.pdf


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8 hours ago, rogerl said:

Based upon several hundred hours of cross country '78 J with a mid-time io360 with two blade and '99 O with low time io550 and three blade, flying around 10k and thinking it's flying the engine 'easy' (around 2400 rpm):

J - 155kts, flowing 8 to 10 gph

O - 175kts, flowing 12 to 15 gph

So not that much of a cruise speed differential.  Climb and comfort are wholly separate judgements.  The io550 likes fuel and will eat it if you're generous, but doesn't seem to demand it (up to a point). 

GAMIs on both, O cylinder temps are hard to keep up at those altitudes, while the J occasionally needed some cowl flap action in the summer.

 

And running 12-15 gph through the Lycoming in the J will bump you up in the low to mid 160's KTAS. Even less of a Δ.

On a hypothetical 500 nm trip the J will get there about 15 minutes later than the O. Running LOP that goes to just under 20 minutes. On a 300 nm trip the Δ is about 10 minutes. That maybe significant to some but I don't think it is.

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And running 12-15 gph through the Lycoming in the J will bump you up in the low to mid 160's KTAS. Even less of a Δ.

On a hypothetical 500 nm trip the J will get there 10 or 15 minutes later than the O. That maybe significant to some but I don't think it is.

 

Maybe but a typical Ovation you can bump to 180-185... after getting to altitude in half the time. They are both great and both have their pluses and minuses...

 

 

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6 minutes ago, gsengle said:

 

Maybe but a typical Ovation you can bump to 180-185... after getting to altitude in half the time. They are both great and both have their pluses and minuses...

 

 

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Yes, but in my hypothetical 500 nm trip you may have arrived 20 minutes sooner but I saved 17 gal avgas!

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Ah yes but options, I can drop to 155 at probably 11gph! And stay aloft for 8 hours :)


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If I didn't own the Ovation I'd want an MSE or Encore for sure...


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1 hour ago, gsengle said:

The common advice is keep your cyl from overheating, get the oil temp up when you do start to get the moisture boiled off, preheat below 50f and use single weight oil (and because of this preheat religiously) so that oil will thicken and protect engine between flights, and don't let the plane sit too long without running. Oh and good engine monitor with Gami injectors...

Oh and read and understand this: https://www.jpinstruments.com/wp-content/uploads/2013/05/Mike-Bush-Red-BoxRed-Fin.pdf


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Greg beat me to it. I actually watched one of Bush's webinars last night and he repeated multiple times the mantra about cyl temps. "Take action" when they go above 380F and "take strong/immediate action" if they go above 400F. He runs engines to 3000hr....but then again he is his own AP/IA and knows what he is doing :D

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Another way to look at it is if you fly the R or in my case the S at J speeds they are very similar in economy. I have flown my S with my friend and his C at his speed on a 3 hour trip and we where shocked how close the fuel burn was when we stop to fill up with some cheap feul. I can't remember off hand what the difference was but it was not as different as you would have thought.

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If you're gonna spend Ovation money, it would be more than worth your time to attend the APS class in Ada, OK. If you're at all concerned about engine management, getting to TBO, etc. it's the best education you can get.

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Fun conversations to have...

A call to Bill Wheat as an M20C owner. (Note: Bill is no longer with)

A call to Bob Minnis as an Ovation owner.

The deep technical details delivered by the guys who made the deep technical details.  No sales pitch. Just the facts!  The facts help sell the plane/engine.  The first trip down the runway does the rest.  :)

Its Fun being a Mooney Pilot.

Best regards,

-a-

Edited by carusoam
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17 minutes ago, bluehighwayflyer said:

We own both a C and a J and between the two the J is MUCH more efficient. We have flown the two in formation on many occasions and between the J's improved aerodynamics and it's improved engine efficiency and ability to fly LOP there is no comparison in terms of efficiency. I would agree with you, though, that a C and an R are probably much closer in efficiency than most would think.  Actually an R pulled back and a J are probably going to be much more comparable than the C is.  

You make a great point with the 3 models. When I play around with economy and J speeds in my plane I usually see 15 nmpg vs in my last J I would see 17 nmpg. With the those power settings in my plane I would expect the engine to last 3X the recommended TBO. 

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Although there are some ways in which running the engine at too low power can be bad for it too...


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I posted the following in September, 2014:

=======================================

I'll begin by saying this isn't meant as a competition, but rather to extol the virtues of both models, and to say that if it was a competition between 2 Mooneys, everybody wins!

I had a really interesting formation flight in my M20C and a friend who has an M20R Ovation 3. We were flying at 2500', and we compared fuel flow numbers. I set power and leaned to the book numbers, airspeed was identical (formation).

M20C: 25"x2500 rpm, 84% power

FF: 12.3 gph

M20R: 13.8 gph

 

M20C: 24x2400 rpm, 78% power

FF: 11.0 gph

M20R: 13.2 gph

 

M20C: 23"x2300 rpm, 71% power

FF: 10.0 gph

M20R: 9.7 gph (LOP)

 

I wasn't too surprised by the M20C's greater efficiency because of course I weigh about 800 pounds less.

The thing I marvelled at is that we each have the most efficient airplane for our missions; I typically fly no more than 300 miles with one passenger. The M20R would be inefficient for my mission profile (particularly taking into account the acquisition cost).

My friend flies for his business with 2 passengers, significant baggage, and 500-2000 miles. He is TKS equipped and needs the ability to get altitude to top weather. My M20C would be inefficient for his mission profile.

Yet another reason to love all Mooneys!

BTW, he 'goosed' his Ovation to 75% power and casually left me behind. Then again, for $500k, he should!

=============================
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The assumption is that the K-factors where 100% correct. The proof is at the pump when both planes start at a known level and finish with a refill to that level. 

 

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I tried to find some relevant data; this is the best I could do.  (Also, keep in mind that while searching the internet, you know everything written is true.)

The best numbers I could find for the Brake Specific Fuel Consumption, (BFSC), of the IO-360 and IO-550 are about the same:  0.435 lb/hp/hr.  In other words, both engines burn the same amount of fuel when delivering the same horsepower.  This means that if you take two airplanes with the same drag, (i.e. the same size, shape, weight), flying the same true airspeed, they will burn the same amount of fuel, and provided you have them leaned the same.  The BSFC presumes you are burning stoichiometrically; that is with the fuel-air mixture that leaves no fuel unburned. 

So, make sure your Mooney has nothing on the outside to disrupt airflow, take out any non-essential weight, run LOP, and you will get the most airspeed for the least fuel.  Since airspeed is dependent on hp, you will always burn more per the square of your airspeed increase.  Are there drag differences between J-models and Ovations? Probably less than the differences between many Js.

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