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  #31  
Old 11-20-2019, 05:29 PM
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rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by NewbRVator View Post
I was wondering besides more HP what are the best airframe mods for higher top and cruise speeds? How are the “racers” getting a higher speed on a given fixed propulsion system
Search Dave Anders here. He's got one of the fastest naturally aspirated RVs around. Lots of aero and engine mods to get there.

As some of the thread photos have gone MIA, you can see some info and photos on our "Dave Page" here: http://www.sdsefi.com/dave.htm
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Last edited by rv6ejguy : 11-20-2019 at 05:35 PM.
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  #32  
Old 11-20-2019, 05:32 PM
Kyle Boatright Kyle Boatright is online now
 
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Quote:
Originally Posted by rv6ejguy View Post
Search Dave Anders here. He's got one of the fastest naturally aspirated RVs around. Lots of aero and engine mods to get there.
Plus he has written a series of articles in Kitplanes if you have access to their archives.
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  #33  
Old 11-20-2019, 06:33 PM
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rocketbob rocketbob is offline
 
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I often fly a T182T which I also maintain. Typically out of the initial climb I dial back to 2000 RPM 28" and lean for 1600 TIT ~12.3 GPH. I just keep that power setting after leveling off. Adjust cowl flaps as necessary to keep it cool. Cowl flaps open I typically see 380 CHT in climb. With the cool temps now it will cruise around 340 CHT with the cowl flaps closed. Heat on this airplane is entirely manageable. In reality the turbo simplifies operations as you can run one power setting in climb and cruise.

Would love to have this type of turbo setup in an RV but it would have to be in one of the longer-winged airplanes (-9, -10, etc.) as the high aspect ratio wing works better for higher altitude ops.
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  #34  
Old 11-20-2019, 10:43 PM
Turbo69bird Turbo69bird is offline
 
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Quote:
Originally Posted by skylor View Post
Mark, Mark, Mark,

Torque alone doesn't make anything go! Torque is a measurement of force only and is but one component required to motivate something. To actually move something, we need to do "work" which is defined as force x distance. And doing that "work" in a finite amount of time requires "power" which is amount of work performed in specific amount of time or work/time. For example, a car's brake can apply force or "torque" to the wheel(s) of a car parked on a hill to keep it from rolling, but it certainly can apply torque while rotating the wheel (work) and it definitely can't rotate the wheel very fast...

Let's try a little though experiment:

Imagine a person with a long torque wrench, say like this 3/4" drive 600 ft-lb model Torque Wrench

With this torque wrench, we can apply up to 600 ft-lbs of torque to something...maybe even a prop hub. How much torque did you say that IO-550-N makes at 2700 RPM and 310 HP?*

OK, so said person (or people) can use that wrench to apply torque to our airplane's prop hub, but to make the plane move we actually have to turn that prop, i.e. do work on it. Of course, even though our torque wrench person is capable of applying a lot of torque with that torque wrench, he's probably going to get tired after trying to turn our propeller more than a few revolutions (doing all that "work") but more importantly, he probably can't turn it very fast while applying all that torque, certainly not 2700 RPM. I.E. he can't make much power.

So you see, torque is not what makes airplanes go!

*So the IO-550-N making 310 hp at 2700 RPM is producing 603 ft-lbs of torque. How much power do we get with 603 ft-lbs of torque at only 2000 RPM? About 230. Is the plane going to go as fast with that same torque at 2000 RPM? Thus, as I said, it's actually power that makes our airplanes go fast.

Skylor

p.s. Horsepower = Torque*RPM/5252. Torque is our measurement of force, "revolution" is our measurement of distance (work) and "per minute" is our "over time". Power = work over time (work/time). The 5252 is simply a unit conversion factor of 550*60/Pi. Part of the reason that it's believed that "torque" is what makes things go is because aircraft engine output figures are very often compared at the same RPM (2700) and thus the torque values of engines of different power are directly comparable...but torque without a measurement of speed (RPM) does not tell us anything about the capability of an engine and how fast it can make an airplane go.
Question:
If the prop was maximized for that 2000 rpm wouldn’t it do the same. Like gearing in a car.
One thing I’ve learned w Pontiacs is they like to be maximized for torque and at a lower RPM can’t build them like a Chevy they won’t live. So if he made the same
Torque at a lower RpM and proped it accordingly like a 308 gear as opposed to a 4.11 gear wouldn’t that make the same amount of work? and therefore propel
The plane the same speed at a lower rpm?
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  #35  
Old 11-20-2019, 10:47 PM
Turbo69bird Turbo69bird is offline
 
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Quote:
Originally Posted by Sue View Post
How fast (horsepower)you want to go?
How much money(and time) you have?
= your answer here.

Not to sounds cocky but
I beat lots of guys at the track that thought money could win races. Loved doing that more than anything else. 😃👍
My favorite saying is:
Knowledge is power!
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  #36  
Old 11-21-2019, 05:28 AM
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rzbill rzbill is offline
 
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Quote:
Originally Posted by Turbo69bird View Post
Not to sounds cocky but
I beat lots of guys at the track that thought money could win races. Loved doing that more than anything else. 😃👍
My favorite saying is:
Knowledge is power!
Great. For zero dollars I can make a stock bug do 0-60 in 2.73 seconds by pitching it off a cliff.

Automotive experience does not automatically translate to aviation. Specifically, the systems used for the highly variable speed automotive engines are simply dead weight for essentially constant speed aviation engines.

Addition of those items probably won't kill you, but your craft will be heavier and more unnecessarily complex than mine at the same engine output.

Here's an idea. How about listening to the advice being given rather than constantly arguing with it. Ask why rather than state yeah but I....
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  #37  
Old 11-21-2019, 07:33 AM
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Ed_Wischmeyer Ed_Wischmeyer is offline
 
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Quote:
Originally Posted by Flash View Post
I have read many threads that speak to changing the pistons from say a 7:1 to a 9.5:1 or 10:1. I have been trying to do my due diligence on this. My engine is a an O-320 H2AD that when it was rebuilt the builder had 7:1 pistons put in instead of the stock 9:1 so he could burn 87 octane. To me, this engine is probably about 150 hp now. My question is with this engine, can new, higher compression pistons and rings be installed without any other upgrade and HP increase to say approximately 170hp or more? I don't see me installing a turbocharger!

Cheers
Scott
There's more to it than that, no surprise. The biggest issue is wide deck vs narrow deck, and if it's a narrow deck, don't soup it up.

Here's a reference: https://generalaviationnews.com/2009...-deck-engines/
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  #38  
Old 11-21-2019, 07:39 AM
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Ed_Wischmeyer Ed_Wischmeyer is offline
 
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All this talk about more speed, etc, turbos. Anybody every think about flutter? One of my buddies is a DAR for structures and for flutter, and he tells me that flutter excitation comes from indicated airspeed but damping comes from true airspeed... or something like that. If you do even a little research, you can find some gliders, for example, that show redline airspeed (indicated) decreasing with altitude. Van's has posted on this in the past.

I never understood why folks would want to take the wonderful RV handling and then fly straight and level for hours on end. And if you want a faster airplane, go buy one.

All this stuff about world's fastest RV whatever reminds me of that line from a W.C.Fields movie where he's a carnival huckster, inducing folks to come see "the world's largest midget."
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RV-9A at KSAV (Savannah, GA; dual experimental touch screens with autopilot, IFR GPS)
Previously RV-4, RV-8, RV-8A, AirCam, Cessna 175
ATP CFII PhD, so I have no excuses when I screw up
2020 dues slightly overpaid
Retired - "They used to pay me to be good, now I'm good for nothing."
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  #39  
Old 11-21-2019, 08:06 AM
rocketman1988 rocketman1988 is offline
 
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Default yep...

"...if you want a faster airplane, go buy one..."

As nice as the RV aircraft are, they aren't the fastest out there. It is great to experiment but if you want a really fast aircraft, it is probably better to look elsewhere than try and make the RV something it is not...

...and you are correct about flutter; it isn't anything to play with...and it doesn't matter how "good" you think you are...

Funny that this would come up again just a day after the anniversary of the Tacoma Narrows Bridge incident...
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  #40  
Old 11-21-2019, 08:47 AM
Flash Flash is offline
 
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Quote:
Originally Posted by Ed_Wischmeyer View Post
There's more to it than that, no surprise. The biggest issue is wide deck vs narrow deck, and if it's a narrow deck, don't soup it up.

Here's a reference: https://generalaviationnews.com/2009...-deck-engines/
Thanks Ed, funny I had just looked at that article last night but I hadn't heard to not soup up a narrow, so it only told me how to identify which was which. Mine is one of the exceptions and has wide cylinders.
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