Glide Ratio
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Re: Glide Ratio
Both of those aircraft have the rear window, the early model 150 and of course the 140 don’t.
When Cessna added the rear window, they lost cruise speed, from an increase in drag, and drag will affect glide to of course.
Then add in the nose wheel that is way more draggy than a tailwheel, a 140 ought to have a better glide ratio than pretty much any of the smaller single engine Cessna’s anyway, a 177 RG is probably better due to the retracts and the Laminar flow wing
When Cessna added the rear window, they lost cruise speed, from an increase in drag, and drag will affect glide to of course.
Then add in the nose wheel that is way more draggy than a tailwheel, a 140 ought to have a better glide ratio than pretty much any of the smaller single engine Cessna’s anyway, a 177 RG is probably better due to the retracts and the Laminar flow wing
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- maverick_fa
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Re: Glide Ratio
You know your stuff. The omni-vision windows was introduced on the C150d...
''The 1964 "D" model brought the first dramatic change to the 150 – the introduction of a rear window under the marketing name Omni-Vision.''
I found the POH from a C150c... top speed 127 mph vs the C150m is 113 kts (119 mph).
The C150 POH doesn't show the glide ratio...
link C150c POH: https://flygklubben.se/files/Cessna-150 ... Manual.pdf
So what is the glide ratio for the C140?
I want to test but I'm doing a major overhaul on mine... already... :
Mat | CSG3
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Re: Glide Ratio
I use a mile for every 1000 feet. I don't want the last words out of my mouth to be "But the guy on the internet said we could make it". Also, once the engine quits, it's the insurance company's airplane and its only purpose is to protect life during the forced landing.
John Cooper
www.skyportservices.net
www.skyportservices.net
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Re: Glide Ratio
An issue with glide ratio is, is the prop stopped or windmilling?
Stopped significantly decreases drag, but to stop it requires slowing way below best glide and then an increase back to best glide, and you lose altitude doing both, so is stopping the prop more than make up for it?
My gut says if you have lots of altitude, like thousands of feet maybe stop it, but if not don’t try.
It took 120 mph to get my engine going again from the stopped condition.
Interestingly to me, it’s a lot harder to stop the prop on my Mooney with its high compression engine than my 140 with its 6 to 1 compression, you would think the opposite.
Stopped significantly decreases drag, but to stop it requires slowing way below best glide and then an increase back to best glide, and you lose altitude doing both, so is stopping the prop more than make up for it?
My gut says if you have lots of altitude, like thousands of feet maybe stop it, but if not don’t try.
It took 120 mph to get my engine going again from the stopped condition.
Interestingly to me, it’s a lot harder to stop the prop on my Mooney with its high compression engine than my 140 with its 6 to 1 compression, you would think the opposite.
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Re: Glide Ratio
I had this conversation my instructor yesterday & he totally agree
He told me don't look for an airspeed but look for the attitude
In most GA airplane we will get same Attitude in Vbg (Best Glide) vs Normal Cruise Attitude (ie 2300rpm 100 kts for a C172)
The ''Aiming Point'' in our windshield will be the gliding distance
We a also add this conversation about the importance of knowing the gliding performance of our aircraft in case of emergency landing for the 360° turn/descent type of approach:
-C152 is ~500fpm @ 15° of bank
-C172 is ~600fpm @ 15°of bank
This is way more important than the gliding distance chart
Mat | CSG3
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Re: Glide Ratio
I agree that any plane will glide further with the prop stopped than it will if it continues to windmill. Back in the ‘80 s I was restoring a J-3 and the company moved me from Oklahoma to Southern California. I loaded the project on my trailer and headed west. As I traveled I watched the wood prop rotate in the wind, one turn about every 50 miles or so. I completed the plane and was then transferred to Tucson. I had heard old stories about shutting down the engine and soaring in a Cub if the conditions were right. I thought I would give it a try. I climbed up to about 4000 feet agl, no mean accomplishment in a J-3, and shut the engine down. Had to almost stall the plane to get the wood prop to stop. I was amazed how the plane creaked and groaned without the engine making all the noise. After a few minutes of very quiet flying I decided to put the plane in a gentile dive to get the prop turning and start the engine. I put the nose down, a little more down, a lot down! And I was still looking at an apparently immovable propeller. Fortunately I was smart enough to commence my foolishness near the Avra Valley airport and headed for the runway. Landed without incidence, started the engine, and continued my flight a little more humble and wiser.
Steve Hawley
Steve Hawley
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Re: Glide Ratio
Steve, with that kind of experience being now shared, you may be called to help plan (or, participate) in the next Red Bull "experiment" .8224 wrote: ↑Tue Apr 26, 2022 10:18 am I agree that any plane will glide further with the prop stopped than it will if it continues to windmill. Back in the ‘80 s I was restoring a J-3 and the company moved me from Oklahoma to Southern California. I loaded the project on my trailer and headed west. As I traveled I watched the wood prop rotate in the wind, one turn about every 50 miles or so. I completed the plane and was then transferred to Tucson. I had heard old stories about shutting down the engine and soaring in a Cub if the conditions were right. I thought I would give it a try. I climbed up to about 4000 feet agl, no mean accomplishment in a J-3, and shut the engine down. Had to almost stall the plane to get the wood prop to stop. I was amazed how the plane creaked and groaned without the engine making all the noise. After a few minutes of very quiet flying I decided to put the plane in a gentile dive to get the prop turning and start the engine. I put the nose down, a little more down, a lot down! And I was still looking at an apparently immovable propeller. Fortunately I was smart enough to commence my foolishness near the Avra Valley airport and headed for the runway. Landed without incidence, started the engine, and continued my flight a little more humble and wiser.
Steve Hawley
Mac