A36 Bonanza Anemic Climbs

[Cpt_Kirk]

A36. IO-550 NA. Full tanks with 10 gals in the tips. Full MAP, 2,500rpm. 110 inidcated. Vortex gens. Mixture leaned continuously. Air conditioning off. Barely 700 fpm initial and below 500fpm above 6,000msl.

Does anyone else see an issue? I figured a Bonanza should be doing a lot better in the climb.

 

[Checkout_my_Six]

what's the gross weight? and DA?

 

[Non Compos Mentis]

How many passengers, or more specifically, what is the weight of the airplane? What was the temperature?

Leave it at 2700 rpm. Better climb, easier on the engine, and it's certified for 300 hp continuously.

Does the engine have the Altitude Compensating Fuel Pump? Quite a few IO-550-powerd Bonanzas do. If so, leave it full rich.

 

[N801BH]

How many passengers, or more specifically, what is the weight of the airplane? What was the temperature?

Leave it at 2700 rpm. Better climb, easier on the engine, and it's certified for 300 hp continuously.

Does the engine have the Altitude Compensating Fuel Pump? Quite a few IO-550-powerd Bonanzas do. If so, leave it full rich.

Yup...

That extra 200 RPM's will make a BIG difference...

 

[Aaronk25]

Its a education issue. No fault of the poster but it's amazing how many people think backing off the rpm has some sort of positive out come.

I cruise my NA internal combustion engine at 2700rpms full time at 9000 and above. There really isn't that much difference between 2700 and 2500 or even 2300rpms. It's not like we're asking these engines to cruise at 5000rpms.

 

[LDJones]

Report back on 2700 RPM climb. That's SOP.

 

[tonycondon]

110 seems fast

 

[Henning]

A36. IO-550 NA. Full tanks with 10 gals in the tips. Full MAP, 2,500rpm. 110 inidcated. Vortex gens. Mixture leaned continuously. Air conditioning off. Barely 700 fpm initial and below 500fpm above 6,000msl.

Does anyone else see an issue? I figured a Bonanza should be doing a lot better in the climb.

What was the density altitude and how close to gross were you? You don't really have a whole lot of excess HP to climb with when heavy, plus you were climbing Above Vy at cruise climb speed. If the weather/DA conditions were sub optimal, that could account for that performance.

 

[James331]

Compare your climb to your book climb, use the same speeds, weights and settings.

On the IO550 I flew I climbed top of the green all the way up.

 

[Cpt_Kirk]

How many passengers, or more specifically, what is the weight of the airplane? What was the temperature?

Leave it at 2700 rpm. Better climb, easier on the engine, and it's certified for 300 hp continuously.

Does the engine have the Altitude Compensating Fuel Pump? Quite a few IO-550-powerd Bonanzas do. If so, leave it full rich.

1 pax in back.

I know this.

No, I lean in the climb.

Its a education issue. No fault of the poster but it's amazing how many people think backing off the rpm has some sort of positive out come.

I cruise my NA internal combustion engine at 2700rpms full time at 9000 and above. There really isn't that much difference between 2700 and 2500 or even 2300rpms. It's not like we're asking these engines to cruise at 5000rpms.

Don't assume things. It's not an education issue and I agree with you more than you realize. I don't think 2,500 rpm "saves" the engine. I bring it back because my pax don't have headphones.

110 seems fast

I thought so, too.

I have another trip tomorrow. I'll make some adjustments and report back. Can't wait to see how many others think I'm an idiot before morning.

 

[Henning]

I doubt you have a problem, but since it's pretty easy to see, you might want to take a look at your alternate air door and make sure that everything looks squared away there.

 

[SCCutler]

I don't think you're an idiot; I use different numbers, though.

I stay at 2700 until I reach cruise altitude, unless there is a noise-abatement reason, in which event, I pull it back until reaching a little higher altitude. Absent a reason for a lower speed, climb is at 120 knots (for cooling); might climb a little slower airspeed/higher rate if cool enough. Keep an eye on CHTs.

WOT, 2700, 120 knots, fairly heavy, I'd expect 800 fpm +/- - but it has been a while since I flew the A36. Good solid plane, but not a rocket in climb.

Used to fly a Debonair with a 550; homesick angel, she surely was!

 

[Henning]

The nice thing about flying HP twins is that I pulled back LOP 25" 2675 at 200' down to 23.5 gph (65% a side approx) and climbed 120kts and 1500fpm.

 

[Non Compos Mentis]

1 pax in back.
No, I lean in the climb.

I don't think 2,500 rpm "saves" the engine. I bring it back because my pax don't have headphones.


I have another trip tomorrow. I'll make some adjustments and report back. Can't wait to see how many others think I'm an idiot before morning.

Definitely not an idiot. Appropriate question. I do think the airplane should climb better than what you experienced, as you were most likely well under gross weight.

Please let us know what the results are at 2700 and flying closer to best climb rate. Only reason to climb at 110 is if the airflow is needed to keep cylinder temps happy.

- I'm assuming 110 knots? 110 mph isn't too far off......

 

[Henning]

IIRC Vy is 100 and book cruise climb is 110. According to his numbers he is climbing probably around 72% power. Add a bit of heat to the day and you have a 700fpm climb. What was the initial RoC on take off up to power reduction?

 

[Cpt_Kirk]

Definitely not an idiot. Appropriate question. I do think the airplane should climb better than what you experienced, as you were most likely well under gross weight.

Please let us know what the results are at 2700 and flying closer to best climb rate. Only reason to climb at 110 is if the airflow is needed to keep cylinder temps happy.

- I'm assuming 110 knots? 110 mph isn't too far off......

Book says 100 and cruise climb is 110 (99% sure). In reality, I'm doing 105 kias, or whatever gives me the best rate while keeping the pitch angle low(er(for pax comfort)), and temps under control (hottest CHT is about tree fiddy).

OAT is usually 25c+ and humidity through the roof (GA & FL during summer).

IIRC Vy is 100 and book cruise climb is 110. According to his numbers he is climbing probably around 72% power. Add a bit of heat to the day and you have a 700fpm climb. What was the initial RoC on take off up to power reduction?

I'd have to look again, but I doubt it's much better. The prop comes back shortly after wheels up and well below 1,000 feet.

I'll see if I remember to snap a pic today for a better visual.

 

[StinkBug]

1 pax in back.

I know this.

No, I lean in the climb.

Don't assume things. It's not an education issue and I agree with you more than you realize. I don't think 2,500 rpm "saves" the engine. I bring it back because my pax don't have headphones.


I thought so, too.

I have another trip tomorrow. I'll make some adjustments and report back. Can't wait to see how many others think I'm an idiot before morning.

I dont think anyone is calling you an idiot......but you did come on here asking about climb performance using non-standard climb settings and didn't give any gross weight, temp or DA information. Makes it a little hard for anyone to know if you have a problem when it's so hard to make a comparison to known performance numbers.

 

[weilke]

I dont have tables for the IO550. I have a 1983 manual with the tables for the IO520. Under 'normal procedures', the manual gives 2700 and full-throttle as maximum continuus power and 25/25 as the setting for cruise-climb.
At 1000ft and ISA+20 2500rpm and 24.8MAP it shows a fuel flow of 15.2gph which corresponds to 214hp or 75%.
At 7000ft and ISA+20 2500rpm it shows a fuel flow of 14.4gph which corresponds to 204hp or 72%

Vy is 96kts
Cruise climb 109kts

With 214hp at the prop initially and 204hp later in the climb, I wouldn't expect more than what you are seeing. The IO550 adds 15hp.

 

[Dr. O]

I remember having a long talk with a bunch of engine gurus at SnF over a cold beer after a long hot day at the show. These were Lyc and Con factory reps plus a smattering of nationally known engine rebuilders - I won't name them but they are in every issue of TAP. At that point in time I had a Super Viking with the IO520D and a 2 blade prop.
Anyway, the consensus was that pilots are pulling back on the engines inappropriately. That the engine maker has the data in the engine manual on continuous running and that as long as you are within time and temp limits and not exceeding the red line, 'balls to the wall and let er wind' is easier on the engine than being lugged down.
The Con rep pointed out he had the same engine as mine in his personal plane. That he routinely ran 2750 in cruise (2850 red line for 5 min on TO and 2800 for continuous) He was 500 hours beyond TBO and the engine was not burning oil and ran smoothly.
They sneered at the 23 square taught by CFI's to new pilots as the blind leading the blind.
Obviously time has moved on and the current generation of "blown within an inch if its life" engines need to be run exactly per the handbook. But for us naturally aspirated types as long as you are not past red line you are not hurting your engine by winding it. And by lugging it down and decreasing the cylinder pressure margin before detonation you may be hurting it by trying to baby it on a hot & thin day.

 

[Dr. O]

I saw Weilke's post after I hit send so let me just let me use that to expand on my comment above.
There is no engine rule that you must have full throttle to turn 2700 rpm.
For a given %HP running 2600 or 2700 and less MP on a hot day will give you more margin against detonation than 2500 and more MP

 

[weilke]

Anyway, the consensus was that pilots are pulling back on the engines inappropriately. That the engine maker has the data in the engine manual on continuous running and that as long as you are within time and temp limits and not exceeding the red line, 'balls to the wall and let er wind' is easier on the engine than being lugged down.

The other issue at least for initial climb is that the conti fuel injection meters fuel by rpm. If you pull back, you reduce your fuel flow while increasing mean cylinder pressures. The Bendix fuel injection meters fuel based on the air-flow through the servo, pulling back to 25/25 will maintain whatever FF is required for that amount of power.

Our plane is a bit different with the turbo and 300hp, but we have found that 2700/36in to cruise gives us a shorter climb and lower CHTs than using a 2500/31in or 2500/29in as a cruise-climb settings. The only reason to pull back would be at a noise sensitive airport, 2700rpm is quite a racket on the outside.

 

[weilke]

There is no engine rule that you must have full throttle to turn 2700 rpm.
For a given %HP running 2600 or 2700 and less MP on a hot day will give you more margin against detonation than 2500 and more MP

Sure, spinning it at 2700 with the throttle pulled back a bit will create lower cylinder pressures, but it still creates more noise, both in the cabin and outside (if that is a consideration).

 

[bullwinkle]

I don't think 2,500 rpm "saves" the engine. I bring it back because my pax don't have headphones.

Um...why not?

 

[Cpt_Kirk]

I've spent hour upon hours researching engine management. That's not my issue here.

I took off this morning (+18c) at near MGW and left the prop at 2,700 for two thousand feet. Result? 850fpm initial decreasing to 750fpm. Bringing the prop back to 2,500 lost me maybe 100fpm overall with a large reduction in noise.

The BEW is 2635 with the useful load being 1275.

I'm not sure I'll get the chance to test this thing out when light as almost all trips are multi-state cross countries. My two issues with the climb rate are that I eventually fall below the min. IFR rate of 500fpm and the M20E I'll fly gets better climb performance at MGW although being a terrible climber.

The pax took a picture this morning and will upload it shortly.

 

[Checkout_my_Six]

the issue I see here is two fold. 1. you're reducing power and want more climb performance.....2. you are leaning and want more power. Both of these actions will not provide more climb performance. Infact each reduces power and reduces climb performance.

My 35 climbs best at 140 mph. That seems to be the sweet spot for climb performance. Try that.....and live with the fuel burn at that speed. Many guru espouse leaving full power with extra the fuel flow for CHT cooling while climbing. After reaching your altitude level then go thru the leaning routine.

 

[Henning]

I remember having a long talk with a bunch of engine gurus at SnF over a cold beer after a long hot day at the show. These were Lyc and Con factory reps plus a smattering of nationally known engine rebuilders - I won't name them but they are in every issue of TAP. At that point in time I had a Super Viking with the IO520D and a 2 blade prop.
Anyway, the consensus was that pilots are pulling back on the engines inappropriately. That the engine maker has the data in the engine manual on continuous running and that as long as you are within time and temp limits and not exceeding the red line, 'balls to the wall and let er wind' is easier on the engine than being lugged down.
The Con rep pointed out he had the same engine as mine in his personal plane. That he routinely ran 2750 in cruise (2850 red line for 5 min on TO and 2800 for continuous) He was 500 hours beyond TBO and the engine was not burning oil and ran smoothly.
They sneered at the 23 square taught by CFI's to new pilots as the blind leading the blind.
Obviously time has moved on and the current generation of "blown within an inch if its life" engines need to be run exactly per the handbook. But for us naturally aspirated types as long as you are not past red line you are not hurting your engine by winding it. And by lugging it down and decreasing the cylinder pressure margin before detonation you may be hurting it by trying to baby it on a hot & thin day.

True, adding RPM reduces ICP for the same horsepower, as well as reducing the heating time on the cylinder head. Reduce fuel flow first and get LOP, then reduce RPM to bring back power once you have the fuel mix down to the lower tip of the 'nose' of the explosive mix curve. The best way to find it is to lean until the power drops off, then slowly enriched the mixture. At one point the engine will suddenly surge in power and the exhaust note will gain a 'throat' to it. Leave your mixture there. That's the least stress way to operate your engine. If you want the greatest traveling efficiency, calculate your L/D max factored by 1.33 and pull your props back to that speed (all the while maintains WOT/Redline MP).

The more RPM you turn, the less likely you will experience detonation. Direct Drive aircraft engines are handicapped by the prop. They have to run really high ICPs to make power, that's why they use such large bores for such low horsepower.

 

[flyingron]

Leaving the engine rpms up and lowering the nose probably does more to "save" the engine.

 

[weilke]

I took off this morning (+18c) at near MGW and left the prop at 2,700 for two thousand feet. Result? 850fpm initial decreasing to 750fpm. Bringing the prop back to 2,500 lost me maybe 100fpm overall with a large reduction in noise.

What kind of instrumentation do you have on the engine ?

What fuel flow are you seeing during that initial WOT climb ?

Has the MP/FF gauge been tested for accuracy ?

With the weights you were giving, you are 310lbs above the originally certified weight for the aircraft. The book numbers are based on a 3600lb plane. It sounds like you have an IO550, tip-tanks and VGs to get to your current MTOW. With the exception of the IO550, none of these modifications add any power, they just shuffle around the numbers on the paper. We have a MTOW of 3849 with the same HP. Loaded to the gills, the plane likes a fair amount of runway and the initial climb is similarly shallow. By changing the STC on our Osborne tanks, we could increase our MTOW to 4024. We decided that nobody in his right mind would want to routinely fly the plane at that weight in the summer.

 

[N801BH]

A36. IO-550 NA. Full tanks with 10 gals in the tips. Full MAP, 2,500rpm. 110 inidcated. Vortex gens. Mixture leaned continuously. Air conditioning off. Barely 700 fpm initial and below 500fpm above 6,000msl.

Does anyone else see an issue? I figured a Bonanza should be doing a lot better in the climb.

Simple physics.....

Naturally aspirated motors loose 3% of their power for every 1000' gain in altitude... Climb to 7000 and you are now at 21% less then you had at sea level...

So, A 300HP motor at sea level is now making 237 HP at 7000 MSL at wide open throttle.... Fuel flows go down at the same rate too.. If you need to burn 20gph @ sea level, it will drop to 15.8gph at 7000MSL..

 

[dans2992]

LOP in climb for a NA engine would result in not enough power for a good climb rate in my experience.

 

[N801BH]

LOP in climb for a NA engine would result in not enough power for a good climb rate in my experience.

Agreed....

You need extra fuel to keep the motor cool....

 

[dans2992]

I've drunk all the LOP kool aid, but frankly with cruise altitudes above 8-9k, I rarely have an opportunity to run LOP.

LOP that high in a NA engine is just too slow!

 

[ktup-flyer]

Lay off the Chipotle

 

[flyingcheesehead]

LOP in climb for a NA engine would result in not enough power for a good climb rate in my experience.

The OP did not say he climbs LOP. He said he leans in the climb. Big difference.

I lean in the climb but I'm running ROP (best power mixture) for the whole climb. There's a handy "climb" range on my EGT gauge for this, but lacking that it's easy enough to just continuously lean to within 50ºF of what your takeoff EGTs were.

Not leaning in the climb, even ROP, means that your mixture keeps getting richer and richer and you keep developing less and less power. If I don't lean in the climb, there is a noticeable degradation of performance.

I don't have much Bonanza experience, but I would have thought it'd perform similarly to the Ovation... And this time of year, I can get 800 fpm at 140 KIAS so something sure doesn't seem right.

OP, what do the performance charts from the POH indicate you should expect?

 

[Cpt_Kirk]

What kind of instrumentation do you have on the engine ?

What fuel flow are you seeing during that initial WOT climb ?

Has the MP/FF gauge been tested for accuracy ?

With the weights you were giving, you are 310lbs above the originally certified weight for the aircraft. The book numbers are based on a 3600lb plane. It sounds like you have an IO550, tip-tanks and VGs to get to your current MTOW. With the exception of the IO550, none of these modifications add any power, they just shuffle around the numbers on the paper. We have a MTOW of 3849 with the same HP. Loaded to the gills, the plane likes a fair amount of runway and the initial climb is similarly shallow. By changing the STC on our Osborne tanks, we could increase our MTOW to 4024. We decided that nobody in his right mind would want to routinely fly the plane at that weight in the summer.

Everything a 1999 Bonanza would come with, as well as a JPI.

Im seeing at or near the correct fuel flow for the PA, corrected with the boost pump on Low, if need be.

Im just not sure, but i dont have any reason to believe they are far off. Everything behaves as if functioning properly. I pull 29"-30" on takeoff with 2,700rpm and the fuel flow on the proper setting.

Im fairly new to this airplane and am now realize that the large increase in MGTOW is the only thing causing the slow climbs. I didnt realize how far over original cert. it was. She sure isnt a performer when heavy, especially in summer. Like i said earlier, we run long trips and we're heavy everytime we depart. I think ill keep that prop at redline for a little longer, if not the whole way up, assuring my pax have some sort of hearing protection.

 

[weilke]

I don't have much Bonanza experience, but I would have thought it'd perform similarly to the Ovation... And this time of year, I can get 800 fpm at 140 KIAS so something sure doesn't seem right.

Why would you expect that ? He is almost 600lbs heavier with the same hp. Physics alone dictate that his climb is less than yours. To boote, you have a lower cross section and drag.

 

[weilke]

Im fairly new to this airplane and am now realize that the large increase in MGTOW is the only thing causing the slow climbs. I didnt realize how far over original cert. it was. She sure isnt a performer when heavy, especially in summer. Like i said earlier, we run long trips and we're heavy everytime we depart. I think ill keep that prop at redline for a little longer, if not the whole way up, assuring my pax have some sort of hearing protection.

Many people dont understand that the effect of stcs on mgw is the result of numbers games, not performance increase. The VGs lower stall and allow part 23 stall criteria at higher wing loading. Tip tanks move the plane out of utility category to obtain the weight bump. Nobody ever tests the additive effects of different stcs. Someone ran a 4049lb G36 off the end of the Cameron airpark because he didn't understand that operation above 3600lbs requires an increase in runway by 1/3.

 

[Henning]

Agreed....

You need extra fuel to keep the motor cool....

No, you need the extra fuel to make power if you are LOP already, but you really don't lose much at 15° LOP, and the heads stay nice and cool. Cooling the cylinders with air is a lot more efficient and kinder to the cylinders and rings than cooling it with fuel.

 

[N801BH]

No, you need the extra fuel to make power if you are LOP already, but you really don't lose much at 15° LOP, and the heads stay nice and cool. Cooling the cylinders with air is a lot more efficient and kinder to the cylinders and rings than cooling it with fuel.

Duh....

I mentioned full rich for the climb out at full power while down low.

 

[Cpt_Kirk]

Many people dont understand that the effect of stcs on mgw is the result of numbers games, not performance increase. The VGs lower stall and allow part 23 stall criteria at higher wing loading. Tip tanks move the plane out of utility category to obtain the weight bump. Nobody ever tests the additive effects of different stcs. Someone ran a 4049lb G36 off the end of the Cameron airpark because he didn't understand that operation above 3600lbs requires an increase in runway by 1/3.

I am more aware of MGW increases and their effect on performance than I may have led, I just wasn't as aware as I should have been with this specific A36. I know what I'm dealing with now.

I used to fly a C337. Reading up on their use as a FAC in Vietnam, they had up to 1,000 (if I remember correctly) MGW increase with no physical addition to the airframe.

Also, there have been accidents attributed to combined STC's on one airframe. Individually, they tested out fine, but nobody tested them when combined with others.