Certify a straight tail 172 for IFR?

[Clark1961]

Umm... What???

Since nobody has repealed Bernoulli's principle, under steady-state or near-steady-state conditions flow in = flow out.

Under the same principle, the restricted section causes an increased velocity => decreased pressure. This decreased pressure is in turn what enables pseudo-vacuum gyro operation.

There will be slightly greater outflow than inflow at the venturi inlet because of the flow through the instruments.

Tom isn't aware that us "brainyacs" can actually consider the entire system and therefore are only worthy of his scorn. Sad state I must say - I've only been analysing systems for twenty years or so...

 

[jesse]

Umm... What???

Since nobody has repealed Bernoulli's principle, under steady-state or near-steady-state conditions flow in = flow out.

Under the same principle, the restricted section causes an increased velocity => decreased pressure. This decreased pressure is in turn what enables pseudo-vacuum gyro operation.

I explain a wing to a student by first drawing a Venturi and put low in the middle then high on the bottom (in relation to each other). Everybody understands that because everyone that remembers a single bit of high school was taught about ventures.

After that part I erase the top half of the Venturi and draw a line across the bottom of the bottom half of the Venturi remaining on the whiteboard and then say "looks a lot like a wing right?"

 

[jesse]

What high pressure or what low pressure ?

In a venturi there is none, your reference even said that. the flow is in one end and out the other, no restriction = no pressure.

That velocity created in the narrow portion creates a flow into that portion. There will be no vacuum pressure created until there is a restriction to that flow.
there is actually more air exiting the venturi than entering the venturi.
Even any old Navy trained Hydraulic mechanic knows this, why does it escape a college brainyack.

Or are you applying the wrong principals, by over thinking the obvious.

Some reading for you Tom:

http://en.wikipedia.org/wiki/Venturi_effect

 

[Tom-D]

Some reading for you Tom:

http://en.wikipedia.org/wiki/Venturi_effect

A better question.

What causes a flow into the venturi's side port?

What causes a pressure to be developed when that flow occurs?

 

[Clark1961]

A better question.

What causes a flow into the venturi's side port?

What causes a pressure to be developed when that flow occurs?

pressure differential causes flow into the venturi's vacuum port

not clear on what you're asking with the second question

 

[Henning]

I explain a wing to a student by first drawing a Venturi and put low in the middle then high on the bottom (in relation to each other). Everybody understands that because everyone that remembers a single bit of high school was taught about ventures.

After that part I erase the top half of the Venturi and draw a line across the bottom of the bottom half of the Venturi remaining on the whiteboard and then say "looks a lot like a wing right?"

You would have loved Jack Thelander for a CFI, he was great; he was also a doctorate aerodynamicist and lead for aerodynamics at Douglas. He had the greatest way to demonstrate this as false. He would prove that the Bernoulian observation was just that, an observation. He postulated that a plane flies on pure Newtonian physics. The way he proved it was with a graphing barometer. Before the flight we determine the weight of the plane, then we go make a low pass over the barometer.

Once we got back inside and get the spike reading from the barometer and measure the opening area and establish the ratio to the wing area. What confused me for a moment was that he came up with more pressure than we even weighed! Then he continued and figure out how much down force the tail was applying, subtracted that and guess what, the numbers were on the mark. The entire weight of the aircraft was being supported on the air column. There was no "lift" being generated, it was all purely an action/reaction factor.

I have watched other PhD aerodynamics guys nearly get into a fight over this., you have to love a geek fight.

 

[Clark1961]

Thank you, Clark.

I never posted any such message Ron, yer making things up. At one point you may have had some training towards being an engineer but you certainly aren't one.

As for insults and other whatnot, you have no room to speak.

 

[Clark1961]

I just copied your example.

Show me where I changed what you posted in quotes. You can't can you? Maybe it's time for you to seek medical help?

 

[Tom-D]

not clear on what you're asking with the second question

Pressure can not occur until there is a restriction.

That is what our brainyack, doesn't understand.

A venturi has no restrictions thru the main air passage.

The venturi will not create any minus pressures in the in the vac port until you hook up a couple gyros, a filter and any other restrictions to that flow that is created when high speed air passes thru the main air passage.

Keep in mind, that an aircraft venturi has no air pumped thru it, the venturi is moved thru the air, thus there is no pressure differential at the intake or exhaust of the venturi. The flow of air thru the venturi, does not create pressure, it simply changes the velocity.

 

[Tom-D]

There will be slightly greater outflow than inflow at the venturi inlet because of the flow through the instruments.
This is true.
Tom isn't aware that us "brainyacs" can actually consider the entire system and therefore are only worthy of his scorn. Sad state I must say - I've only been analysing systems for twenty years or so...

This simply show what a little bi--- you can be when some one disagrees with you.

 

[Henning]

When people argue against plain fact that they refuse to understand, smart people trying to explain do tend to get annoyed. It's exasperating until you just accept stupidity as the norm.

 

[jesse]

You would have loved Jack Thelander for a CFI, he was great; he was also a doctorate aerodynamicist and lead for aerodynamics at Douglas. He had the greatest way to demonstrate this as false. He would prove that the Bernoulian observation was just that, an observation. He postulated that a plane flies on pure Newtonian physics. The way he proved it was with a graphing barometer. Before the flight we determine the weight of the plane, then we go make a low pass over the barometer.

Once we got back inside and get the spike reading from the barometer and measure the opening area and establish the ratio to the wing area. What confused me for a moment was that he came up with more pressure than we even weighed! Then he continued and figure out how much down force the tail was applying, subtracted that and guess what, the numbers were on the mark. The entire weight of the aircraft was being supported on the air column. There was no "lift" being generated, it was all purely an action/reaction factor.

I have watched other PhD aerodynamics guys nearly get into a fight over this., you have to love a geek fight.

I actually am with you that theres more to it which I explain as well. Ultimately though I have to ensure they can pass a checkride per the PTS which means they need to understand what the faa wants to hear for lift.

 

[Henning]

I actually am with you that theres more to it which I explain as well. Ultimately though I have to ensure they can pass a checkride per the PTS which means they need to understand what the faa wants to hear for lift.

I understand, you have to teach them what they need for the test. The reality is it has little to no relevance to the pilot as it doesn't change the effect. I just always find it a fun argument to watch at the PhD level.

 

[Tom-D]

I actually am with you that theres more to it which I explain as well. Ultimately though I have to ensure they can pass a checkride per the PTS which means they need to understand what the faa wants to hear for lift.

There are many theories we see in the aviation industry that are a reaction to an event happening simultaneously.

 

[timwinters]

Show me where I changed what you posted in quotes. You can't can you? Maybe it's time for you to seek medical help?

I think he's confusing you with me (yeah, I know, you should be insulted!). The difference being that my misquotes were clearly tongue in cheek and were prefaced accordingly. What you failed to do Clark is mimic him with an absurd statement like:

Please remove your false and insulting post at once.

 

[Clark1961]

Pressure can not occur until there is a restriction.

That is what our brainyack, doesn't understand.

A venturi has no restrictions thru the main air passage.

The venturi will not create any minus pressures in the in the vac port until you hook up a couple gyros, a filter and any other restrictions to that flow that is created when high speed air passes thru the main air passage.

Keep in mind, that an aircraft venturi has no air pumped thru it, the venturi is moved thru the air, thus there is no pressure differential at the intake or exhaust of the venturi. The flow of air thru the venturi, does not create pressure, it simply changes the velocity.

Tom - you're still lost - I offered to agree to disagree and you can't accept that - see ya around

 

[Clark1961]

I think he's confusing you with me (yeah, I know, you should be insulted!). The difference being that my misquotes were clearly tongue in cheek and were prefaced accordingly. What you failed to do Clark is mimic him with an absurd statement like:

The thought occured to me that he was blaming me for your post. I'll accept the failure to mimic and move on.

 

[Henning]

I wonder if you could increase venturi system performance with a window scoop?

 

[Clark1961]

I wonder if you could increase venturi system performance with a window scoop?

some marginal improvement is available but the drag cost would exceed the value...

 

[timwinters]

some marginal improvement is available but the drag cost would exceed the value...

But wouldn't the extra propulsion produced by the additional flow thru the venturi offset the drag from the window scoop?

 

[Clark1961]

But wouldn't the extra propulsion produced by the additional flow thru the venturi offset the drag from the window scoop?

Ya know, I can't even see that far out on the decimal places...

Maybe Tom's model that doesn't have a pressure drop could tell us. Or maybe Ron's model which mis-attributes posts and craves an apology from anybody can help you.

Me, I can't help. Sorry.

 

[timwinters]

Me, I can't help. Sorry.

Well, dam. I went back and reread my post and I left out the important variable. it should have read:

But wouldn't the extra propulsion produced by the additional flow thru the venturi offset the drag from the window scoop while it's sitting on a treadmill?

 

[Clark1961]

Well, dam. I went back and reread my post and I left out the important variable. it should have read:

But wouldn't the extra propulsion produced by the additional flow thru the venturi offset the drag from the window scoop while it's sitting on a treadmill?

Is the treadmill in the northern or Southern Hemisphere?

 

[timwinters]

Hang on, let me go flush the toilet.

 

[Henning]

some marginal improvement is available but the drag cost would exceed the value...

How about a NACA duct under the wing hosed directly to a gyro feed/filter box?

Would the loss exceed the loss from driving a vacuum pump?

 

[Clark1961]

How about a NACA duct under the wing hosed directly to a gyro feed/filter box?

Would the loss exceed the loss from driving a vacuum pump?

Might work, might be best to use the NACA duct to feed a venturi thus avoiding the profile drag of the external venturi.

Either way you're way down in the small digits for losses. Of course a vacuum pump can be run on ram air too, they don't take much power.

 

[weirdjim]

Maybe Tom's model that doesn't have a pressure drop could tell us. Or maybe Ron's model which mis-attributes posts and craves an apology from anybody can help you.

Throttle, I can't remember that far back. Wasn't this pretty well answered the first or second month of high school Physics? Or did we get to freshman year of engineering school? I misremember.

Jim

 

[jesse]

Throttle, I can't remember that far back. Wasn't this pretty well answered the first or second month of high school Physics? Or did we get to freshman year of engineering school? I misremember.

Jim

The last bit of formal education I completed was ninth grade in a poorly ran rural school. I think I got a D in 9th grade physics and I had no trouble properly understanding this thread or doing the math behind this. How the hell "engineers" can't properly grasp a Venturi I can't explain to you.

 

[Clark1961]

Throttle, I can't remember that far back. Wasn't this pretty well answered the first or second month of high school Physics? Or did we get to freshman year of engineering school? I misremember.

Jim

It's all very confusing at this point with pressuredropless flow and/or magic pressure increases...I'm just gonna burn all my books, cut out the soles of my shoes, sit in a tree, and play the flute.

 

[jesse]

Your FlyBaby has the same problem that the early 170/2s do they simply do not have the panel space for equipment to do a proper layout.

Plenty of room on a Flybaby panel.

 

[Tom-D]

It's all very confusing at this point with pressuredropless flow and/or magic pressure increases...I'm just gonna burn all my books, cut out the soles of my shoes, sit in a tree, and play the flute.

That's probably where you need to be, rather than making sarcastic a$$ remarks here.

 

[Tom-D]

Plenty of room on a Flybaby panel.

What do you call a proper layout ?

I like the typical 6 pack

 

[Clark1961]

That's probably where you need to be, rather than making sarcastic a$$ remarks here.

If you can't take the heat stay out of the kitchen.

 

[Tom-D]

If you can't take the heat stay out of the kitchen.

Been here, staying here because you are no heat. because your post tell us what you really are.

IMHO just a punk trying to bully the page.

 

[jesse]

What do you call a proper layout ?

I like the typical 6 pack

If money were no object..and I had a proper electrical system..I would:

Rip out venturi, turn coordinator, altimeter, airspeed, vertical speed, CGT/EGT, mag ass magneto switch, big ass compass (move the compass elsewhere), and install:

Two of these:

One of these:

One of these:

One of these

You could figure out a way to make it all fit. The GTN and Dynons might have to stick out of the panel a bit to clear the fuel tank..or you could move the panel closer to the pilot.

Dynons would go into the airspeed and altimeter holes.

Garmin would go where the compass and turn coordinator are.

Transponder would go where the EGT/CHT is.

CDI control box could be fit somewhere.

Of course all that would by far exceed the value of the airframe. But man opencockpit IFR would be a blast.

 

[jesse]

Ok, my friend has the test box all ready to go, will pick it up tomorrow and will test fly with it later this week sometime.

 

[SCCutler]

Ok, my friend has the test box all ready to go, will pick it up tomorrow and will test fly with it later this week sometime.

OK, but what is it?

 

[RotorAndWing]

OK, but what is it?

Flux Capacitor.

 

[Tom-D]

You could figure out a way to make it all fit. The GTN and Dynons might have to stick out of the panel a bit to clear the fuel tank..or you could move the panel closer to the pilot.

Of course all that would by far exceed the value of the airframe. But man opencockpit IFR would be a blast.

We were talking about the early 172 and in them your problem would be, most of the early 172s have the small round instrument panel, you'd be required to change the boot cowl to get the larger squarish instrument panel.

But in your E/AB you can simply saw out the old instrument panel and glue in a new one.

 

[jesse]

OK, but what is it?

One of these:
http://arduino.cc/en/Guide/ArduinoProMini

Two of these:
http://www.maximintegrated.com/en/products/analog/sensors-and-sensor-interface/DS18B20.html

A SD card module, and the pelican case.