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Full Power Fuel Flow? What do you show?


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For those that have Ovations, was curious what the full power fuel flows are? Somewhere I thought I read that you needed around 0.1 x HP of engine or so. What do people think? Are people seeing this? Thank you.

 

Freddy

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My 200 Hp motor is 19 at sea level and the prop governor is a little low, so yes I’m right at that .1 you speak of.

‘But I don’t know about others

Edited by A64Pilot
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310 or 280? I have found 31 is too rich for the majority of operations. 29.5 is where we settled in at.  The 280 is also happy well below .1 and not nearly as hot as the 310. 

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Posted (edited)

I'm around low 22's sea level and 280 HP. This will need to be probably be sorted out. Given the 29.5 for 310, I probably should be about 26.5. I need to consider this before it gets hot and the CHT's climb! Thoughts?

Freddy

Edited by FJC
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Great reference though, PJ!


I can’t find my reference book right now... these numbers may be a bit off....

For the 280hp, 2500 rpm Ovation we have one FF number around 25gph max...

For the 310hp, 2700 rpm we get a different number for FF....  the STC gives a range.... that is user unfriendly...

Getting the FF raised from the 26gph to 28-30.... takes additional knowledge....

The excess fuel is used for CHT control...

The Missile with the IO550 (A) is also 300hp and bumps into a CHT limit using the 25gph FF number as well...

Having the FF set too low... CHTs become a challenge in a long climb... cutting back the throttle isn’t always appreciated...

It is possible to set the FF too high as well..... the danger is the engine doesn’t produce full power as needed...


PP thoughts only, check your FF numbers from a reliable resource...

Best regards,

-a-

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8 hours ago, FJC said:

I'm around low 22's sea level and 280 HP. This will need to be probably be sorted out. Given the 29.5 for 310, I probably should be about 26.5. I need to consider this before it gets hot and the CHT's climb! Thoughts?

Freddy

I'm at 25 gph (95 lph) on 280 hp. This keeps the Cht's < 390F on takeoffs up to about an OAT of about 100F. It took multiple attempts at increasing fuel flow bit by bit to achieve the right balance.

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At 244hp i was at 23gph, meaning your 22 is way too low. 310hp is now at 28.4gph. 26 sounds about right for 280hp. It doesnt matter now, since its cool. It will in the summer though.

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9% of rated horsepower for a normally aspirated engine is a good rule of thumb.  Mooney S/I M20-107 is your reference.

https://www.mooney.com/wp-content/uploads/2020/12/SIM20-107.pdf

The current version of Continental SID97-3G no longer covers the IO-550 series engines, for these you need t9 refer to Continental’s manuals.

The Busch reference above quotes obsolete references.

My 400 hp IO-720 runs 36-38 gph at full power.

Clarence

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I utilize the data given by Lycoming's IO-550 Permold Series Engine Maintenance & Overhaul Manual as primary source:

For my IO-550-G the FF(BHP) chart reads a little bit less than 130lbs/hour for full power at full rich under sea level conditions.
This converts in a FF of app. 22.4gal/h. 

Combine this chart with the BHP(MAP) chart and you can derive an estimate of what you could expect at higher altitudes/lower QFE during full power take off run. Take the local pressure (QFE), subtract 0.5"inch/Hg for pressure drop in air filter. Read the expected BHP at max RPM. 

Put the BHP in the FF(BHP) and read the estimated FF you could expect fo full rich/WOT.
Just a rough estimation not considering the influence of ISA temperature deviation though. But based on the engine manufacturer's data.

PPL thoughts only, no A&P.

Regards,

Matthias

image.thumb.png.06d1e125c2540882a93f6fbc24d5e1b2.png

image.thumb.png.a7fc8b0e7b89dae465440f17c038f636.png

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10 hours ago, A64Pilot said:

What do you have with a 720 in it? I’ve only seen them in a braves 

I own a Piper Comanche 400.

Clarence

5F6563A7-793B-4D36-A798-AC497BAA2AFA.jpeg

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5 hours ago, M20Doc said:

I own a Piper Comanche 400.

Clarence

5F6563A7-793B-4D36-A798-AC497BAA2AFA.jpeg

I wasn’t aware of them, do you have any cyl head temp issues. the Braves I believe did.

‘Is it the same airframe as the 250?

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10 hours ago, M20Doc said:

I own a Piper Comanche 400.

Clarence

5F6563A7-793B-4D36-A798-AC497BAA2AFA.jpeg

 

I see a lot of similarity -- except for the wings :) (I trust the Piper is more reliable).

 

AutoArt 1966 Jaguar E-Type S1 3.8 Roadster 1:18 scale image 0

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So far so good with the 400, it’s been no real problem to maintain.  The fuel burn to performance is quite acceptable in my experience.

Clarence

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7 hours ago, A64Pilot said:

I wasn’t aware of them, do you have any cyl head temp issues. the Braves I believe did.

‘Is it the same airframe as the 250?

There were 148 built and supposedly 146 sold in 64 & 65.  Less than a hundred left now and only three in Canada.  The airframe is basically the same as a 250 with higher gross and useful load, more fuel and way more performance.  I’ve spent a lot of time improving and sealing all of the baffles and have relatively cool temps.  375-380 in the climb and sub 350 in cruise. It’s hard to get all eight LoP.

Clarence

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I’m approx 30gph (slightly more) with everything forward near sea level in an O2 with 310hp. I insisted on this setting when I bought the plane and I’ve made it clear to every mechanic that it’s not to be lowered. I find that CHTs climb until I bring the RPM back to 2500 shortly after departure. 

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23 hours ago, M20Doc said:

There were 148 built and supposedly 146 sold in 64 & 65.  Less than a hundred left now and only three in Canada.  The airframe is basically the same as a 250 with higher gross and useful load, more fuel and way more performance.  I’ve spent a lot of time improving and sealing all of the baffles and have relatively cool temps.  375-380 in the climb and sub 350 in cruise. It’s hard to get all eight LoP.

Clarence

I imagine it is fast, the 250 is no slob, it was one of the airplanes on my short list. The Mooney works for us as since I’m old and retired there are only two of us, but if there were occasionally four I would have looked harder for a 250

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1 hour ago, A64Pilot said:

I imagine it is fast, the 250 is no slob, it was one of the airplanes on my short list. The Mooney works for us as since I’m old and retired there are only two of us, but if there were occasionally four I would have looked harder for a 250

It’s reasonably fast, the best I’ve seen was 199KTAS, but 190 is a good number.  
 

Clarence

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14 minutes ago, M20Doc said:

It’s reasonably fast, the best I’ve seen was 199KTAS, but 190 is a good number.  
 

Clarence

That’s interesting as the Meyers 200D is often quoted as the fastest single engine N/A GA aircraft, and I believe they are about 185 kts, so yes 190 is fast in my book

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