Cruise Speed for a Mooney Screaming Eagle (280 HP)

[M20S Driver]

My 280 HP Eagle does 180 kts at gross weight.  I expect it to do 190+ since the Ovation at 280HP and higher gross weight (3200 VS 3368 for Ovation) claims to do over 190 kts.  I have a HTZ  three bladed prop.

Can anyone shed some light on this?  My climb rates are as good as the numbers in POH for Ovation.

[carusoam]

Welcome aboard,

O1 cruises at 175 kts at WOT, 10,000' ROP. 165 kts LOP... Give or take....

2,500 rpm as well....

Does your Eagle have the 2700 rpm limit with the TopProp?

Best regards,

-a-

[carqwik]

As an indirect answer...identical Mooney airframes do not perform the same speeds in cruise at identical power settings based on my limited experience.  My test basis was among the six 252s I flew that were available as rental aircraft in Southern California (LA area) in the mid- to late 80s.  (N252A, N252MC, N252YX, N252YA(?), N252NM,,,darn, forgot the last one!)  Each one was a little bit different in cruise...I'd say the spread was about 10 kts between the fastest and the slowest.  All were pretty much identically equipped IIRC except N252A which only had one alternator and no oxygen built in as I recall.  And it was not the fastest...that was N252YX...a superb running airplane.

[carusoam]

In this case the planes are not identical, and neither are the engines or props....

Ovations are typically heavier than Eagles because of their extra nick knacks...and fuel loading.

HP runs from 240 to 310.

Prop can be two or three blade from at least two different manufacturers...

Rpm limit may be 2,500 or 2,700.

I like the O3, 310hp, with 2700 rpm on a TopProp...

Best regards,

-a-

[M20S Driver]

My Eagle is a 2500 RPM Screaming Eagle producing 280 HP.  Its prop can be set to do 2700 RPM which makes it a 310 HP screaming eagle after a fuel pump set-up.

I saw numbers as high as 197kts in the Ovation-2 POH and 190+ in Ovation-1 POH .  Perhaps it is not real!  If Ovation-1 cruises at 175 kts, Eagle at lower gross weight and the same HP should do better--- which is where 180 is coming from.  Ovation-2 has a two bladed prop optimized for cruise.

[carusoam]

2700 rpm is a bit loud...

Great for getting off the ground, though! But for cruise, not so much... Ymmv...

-a-

[M20S Driver]

I agree.  The 310 HP at 2700 RPM is time limited and CHT limited.  You can do 2550 rpm in cruise which may buy a couple of knots.  I am fine with the 280 HP at 2500 rpm.

 

I fly in and out of Truckee in CA where the density altitude is usually over 8000 feet in the summer (my personal limit is 8500 feet). I may consider the 310 HP STC if my kids get older and heavier!  Of course, I could make up for it by losing weight

[Z W]

What power settings and altitudes are giving you 180 KTAS?  Often by increasing fuel flow and manifold pressure you can eek out another 10 knots, usually at a cost of several gallons per hour of fuel burned.

 

I have no experience flying Ovations or any long-body, but from what I've read on Mooneyspace, most Ovations cruise at 170-180 KTAS like your Eagle.  They may be capable of 190, but the last 10 knots takes so much fuel, it greatly decreases your range and economy.

 

Your best speed will probably be wide open throttle, around 10,000 feet, 150 degrees rich of peak EGT.  You might try that setting and see how you like the fuel flow and cylinder head temperatures.

 

"Book" numbers always give those unrealistic top speeds for marketing reasons.  Many owners choose to trade that last 10 knots for 3 GPH and a cooler engine.

[Bob_Belville]

@ 2700 RPM I would cruise @ 160 k or slightly more in my '66E on 200 HP & 11 GPH. 900# useful. <grin>

[PMcClure]

My 280 HP Eagle does 180 kts at gross weight.  I expect it to do 190+ since the Ovation at 280HP and higher gross weight (3200 VS 3368 for Ovation) claims to do over 190 kts.  I have a HTZ  three bladed prop.

Can anyone shed some light on this?  My climb rates are as good as the numbers in POH for Ovation.

N1051K is a 280hp/2500 rpm O2 and I can get 187-190 TAS at 50 ROP at 9-11,000' and 180-184 TAS 50 LOP with the three blade prop. 

[Cris]

My Screamin' Eagle will exceed the Ovation numbers for similar power settings and weight but first and foremost is the need to check the rigging. That will give you confidence that the A/C is optimized for cruise. In my own case on a 300 hr. airframe the right gear door needed adjustment which added a couple of knots. In addition there is the obvious of flying a clean and waxed airframe as you are comparing POH numbers which are optimized by the factory. BTW I also started with the 280 HP STC and upgraded to the 310 STC. It makes a world of differance on T/O as Anthony points out. It also requires not just the paperwork but a new tach and prop gov. as well as setting the engine up as if it were an IO 550-N. This is necessary for the higher fuel flows required at T/O for not just for power but also for cooling. If you are having CHT issues on T/O I'd suggest checking the fuel flow and also your airspeed. Target at 120 knots.

[M20S Driver]

I have an Eagle, not Screaming, and get 175 kts at 10,000 at 2500rpm. That's on 245hp. You guys should be seeing more than that.  

 

Spenscot,

 

My understanding of Eagle is that it produces 244 HP at 2400 RPM.  If you can go up to 2500 rpm, it is the same as my screaming eagle. 

At 2500 rpm on take off, I burn 22.5 gallons per hour.  What is your take off fuel flow?

 

Masoud

[aviatoreb]

My Screamin' Eagle will exceed the Ovation numbers for similar power settings and weight but first and foremost is the need to check the rigging. That will give you confidence that the A/C is optimized for cruise. In my own case on a 300 hr. airframe the right gear door needed adjustment which added a couple of knots. In addition there is the obvious of flying a clean and waxed airframe as you are comparing POH numbers which are optimized by the factory. BTW I also started with the 280 HP STC and upgraded to the 310 STC. It makes a world of differance on T/O as Anthony points out. It also requires not just the paperwork but a new tach and prop gov. as well as setting the engine up as if it were an IO 550-N. This is necessary for the higher fuel flows required at T/O for not just for power but also for cooling. If you are having CHT issues on T/O I'd suggest checking the fuel flow and also your airspeed. Target at 120 knots.

 

Where did you have that rigging done Cris?  I have been looking for a Mooney rigging know legible shop in the North East.

[M20S Driver]

What power settings and altitudes are giving you 180 KTAS?  Often by increasing fuel flow and manifold pressure you can eek out another 10 knots, usually at a cost of several gallons per hour of fuel burned.

 

I have no experience flying Ovations or any long-body, but from what I've read on Mooneyspace, most Ovations cruise at 170-180 KTAS like your Eagle.  They may be capable of 190, but the last 10 knots takes so much fuel, it greatly decreases your range and economy.

 

Your best speed will probably be wide open throttle, around 10,000 feet, 150 degrees rich of peak EGT.  You might try that setting and see how you like the fuel flow and cylinder head temperatures.

 

"Book" numbers always give those unrealistic top speeds for marketing reasons.  Many owners choose to trade that last 10 knots for 3 GPH and a cooler engine.

Zane,

 

8000 to 10000 feet full throttle, 50-70 deg rich of peak gives me 178-180 knots.  I will try the richer mixture that you mentioned (125 deg  ROP) just to find out what the performance is.  Most of my flights are short (1-2 hours) so I can l can live with 10 knots less and have a happier engine and fuel tank

 

Masoud

[Cris]

Erik- it was done at Air Mods, an MSC, at Trenton Robbinsville in NJ

[M20S Driver]

Hello Cris,

 

Long time no talk and thanks for your help in my transition from a Cessna driver to a Mooney pilot.  Your landing tips worked  perfectly

 

I think rigging is an issue on my plane since the balanced ailerons sit slightly higher than the flaps.  This may cost me a few knots.  I will check that in the next annual in December.

 

I may need the 2700 rpm STC to get out of Truckee when my kids get older.  My CHT runs between 370-400 deg C on a hot summer day (in 80s), full power at 8500 DA climbing at 120-130 knots.  I usually climb at 700-900 feet per minute in cruise climb.  My CHT is around 350 in cruise at 8000-10000 feet with 50 deg ROP.  Are these comparable to your experience?

 

Masoud

[aviatoreb]

Erik- it was done at Air Mods, an MSC, at Trenton Robbinsville in NJ

Thanks Cris. Yeah - my mooney has never been trued under my watch so who knows....and I recently have been suspecting it may be pulling slightly to the left. So you like them and they seem like they do a good job? The location is very convenient since in fact I have a work trip to Trenton in fact in November.

[rbridges]

  I am fine with the 280 HP at 2500 rpm.

 

 

 

I guess I could settle for that.  lol

[Parker_Woodruff]

I think rigging is an issue on my plane since the balanced ailerons sit slightly higher than the flaps. This may cost me a few knots. I will check that in the next annual in December.

Masoud

This is normal in appearance. You can still have your control and gear rigging checked. But Mooney ailerons will trail higher than the flaps.

[Spenscot]

Masoud

 

Take off fuel flow is 22.5 gph. I'm a little over 2400, closer to 2460 rpm.

[Cruiser]

The Eagle is the long body replacement for the M20J.(since it was abandoned when the Eagle went into production in 1999)

Actually, the Eagle is an Ovation with different avionics and the de-rated 244HP engine.

The Eagle was advertised as 180kts. true at 15gph in cruise. Cruise was WOT x 2400 rpm in the 8k to 10k altitude range. Remember, it is a normally aspirated IO-550G derated to 244HP by the RPM limit. The prop/governor combination was developed specifically for optimal cruise performance. The two blade McCauley prop being the fastest setup. (I have one for sale if anyone is interested). Basically, your cruise speed is your top speed by limit in RPM. Modification (RPM increase) have been made to increase HP and change from the two blade to a three blade prop mostly because of the long take-off distances and slower climb performance of the stock Eagle. The three blade prop is slower at cruise however. Increasing the RPM allows an increase in HP which in turn gets back the lost speed but not an increase in speed. It also allows a maximum GW increase but that will slow you down also. 

 

I believe the Ovation2 top speeds will be greater then the Eagle only because of the increase in RPM allowing the 280 HP but this was still with a two blade prop. Advertised top speed was 190kts. But they also has increased GW and more fuel. I believe with the additional weight there is not really much speed difference between the two in cruise configuration.

[Cris]

Thanks Cris. Yeah - my mooney has never been trued under my watch so who knows....and I recently have been suspecting it may be pulling slightly to the left. So you like them and they seem like they do a good job? The location is very convenient since in fact I have a work trip to Trenton in fact in November.

They did a good job for me. Another option that many use is Weber Aircraft an MSC in Lancaster Pa. I've used them also for both sales and service. They do an extensive air check as I understand it. Make a call to both.

[Cris]

Hello Cris,

 

Long time no talk and thanks for your help in my transition from a Cessna driver to a Mooney pilot.  Your landing tips worked  perfectly

 

I think rigging is an issue on my plane since the balanced ailerons sit slightly higher than the flaps.  This may cost me a few knots.  I will check that in the next annual in December.

 

I may need the 2700 rpm STC to get out of Truckee when my kids get older.  My CHT runs between 370-400 deg C on a hot summer day (in 80s), full power at 8500 DA climbing at 120-130 knots.  I usually climb at 700-900 feet per minute in cruise climb.  My CHT is around 350 in cruise at 8000-10000 feet with 50 deg ROP.  Are these comparable to your experience?

 

Masoud

I'd say your numbers are close to mine although you will want to try the Pixie hole for your baffles which helped me. Also your T/O fuel flow is to low. I can get close to 400 degrees initially on the Factory guage but immediately take action to reduce the temps. Also I find the Moritz gauges read higher than the G2 engine monitor. This,is particularly true on the EGT'S. if I belived the factory gauge the heads would have melted by now. This is the long way of saying get an engine monitor before you get overly concerned on the temps you describe. Of course if you have a engine monitor that is a differant story.

[Cruiser]

The factory EGT is located below the union of all three cylinder exhaust pipes in the common section going to the muffler. The engine monitor probes are located close to the exhaust of each individual cylinder. These engine probes only see the exhaust gas from it's cylinder and then get a chance to cool until it is their turn again in the cycle. The OEM gauge gets exhaust from all three cylinders on its side and sees the exhaust heat three times as long, only waiting for the exhaust cycle from the other three on the opposite side of the engine. The OEM EGT gauge is always going to report a high temp reading because of this extra long exposure to the exhaust gas.

 

The OEM CHT is located on the #2 cylinder. It only reports what is happening with that cylinder the other five are unknown. It is a common problem with these planes to have this #5 CHT run anywhere from 40°F to as high as 100°F more than the #2 CHT (especially in the climb after take-off) 

[M20S Driver]

The factory EGT is located below the union of all three cylinder exhaust pipes in the common section going to the muffler. The engine monitor probes are located close to the exhaust of each individual cylinder. These engine probes only see the exhaust gas from it's cylinder and then get a chance to cool until it is their turn again in the cycle. The OEM gauge gets exhaust from all three cylinders on its side and sees the exhaust heat three times as long, only waiting for the exhaust cycle from the other three on the opposite side of the engine. The OEM EGT gauge is always going to report a high temp reading because of this extra long exposure to the exhaust gas.

 

The OEM CHT is located on the #2 cylinder. It only reports what is happening with that cylinder the other five are unknown. It is a common problem with these planes to have this #5 CHT run anywhere from 40°F to as high as 100°F more than the #2 CHT (especially in the climb after take-off) 

Hello Cruiser,

 

Thanks for the info.  My CHT runs higher on #3 and #5.  Here is a link to my JPI plot--

 

https://dl.dropboxusercontent.com/u/41259646/2013-09-10%2017_28_59-JPI%20EzTrends%20-%20%5BMain%20Graph%5D.png  

 

My #1 CHT is usually 30-40 deg C cooler than my CHT #5.   EGT #4 is 50 deg hotter than the rest.

 

Masoud