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  #31  
Old 02-04-2020, 06:50 PM
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RV8JD RV8JD is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
Yes, same speeds but the RV-9 is designed for utility category limit loads and the rest are designed for aerobatic limit loads.
But that really doesn't matter if Vno and Vne are obeyed. So I take it that as long as Vno and Vne are obeyed, there are no structural design reasons that preclude the RV-9s from handling the 180 HP engines.

Regardless of engine power, the pilot must ensure that he/she does not exceed the design speeds at all altitudes. But I understand Van's concerns that with the higher power, it is easier for a pilot to inadvertently exceed those airspeed limits, with possibly bad outcomes.

+++++++++++++++++++++

Just a summary of the Design Load Factors and Design Weights for the -9s and the -6s:

RV-9/-9A:
Recommended Gross Weight (Normal Category) ......1750 lbs
Maximum Utility Category Weight ..........................1600 lbs
RV-6:
Recommended Gross Weight (Utility Category) ......1600 lbs
Aerobatic Gross Weight.......................................1375 lbs
RV-6A:
Recommended Gross Weight (Utility Category) ......1650 lbs
Aerobatic Gross Weight.......................................1375 lbs
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Carl N.
Arlington, WA (KAWO)
RV-8, 660 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasflügel Standard Libelle 201B - Sold
Rolladen-Schneider LS1-f - No longer owned

Last edited by RV8JD : 02-04-2020 at 07:14 PM.
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  #32  
Old 02-05-2020, 10:23 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by RV8JD View Post
But that really doesn't matter if Vno and Vne are obeyed. So I take it that as long as Vno and Vne are obeyed, there are no structural design reasons that preclude the RV-9s from handling the 180 HP engines.
Correct

Quote:
Originally Posted by RV8JD View Post
Regardless of engine power, the pilot must ensure that he/she does not exceed the design speeds at all altitudes.
I agree and I don't think anyone would dispute that. The problem is that there is often a misunderstanding of what design speeds should be obeyed, and how they impact they way the airplane is operated.

It only takes a little time reading through past forum threads to see this.

Quote:
Originally Posted by RV8JD View Post
But I understand Van's concerns that with the higher power, it is easier for a pilot to inadvertently exceed those airspeed limits, with possibly bad outcomes.
Especially if they have a lack of understanding of what all of the limits are or what they mean.
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Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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  #33  
Old 02-05-2020, 01:13 PM
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Tumper Tumper is offline
 
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I didn’t mean to cause a stink on the forum by introducing science/safety into the discussion. However, I wanted anyone who is considering a 360 with 180HP in their RV-9 to fully understand what they are doing. I am assuming all of us that are flying a 180HP RV-9 have been through this thought process and already know all this.

If you are still a little murky on the subject, please search “Flying High and Fast by Ken Kruger” and spend as much time as is necessary to fully understand where the concerns of 180HP in an RV-9 exist. If you don’t fully understand find a friend to help you.

And…thanks for the great discussion.

It’s a jungle out there, let’s be safe.
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Aubrey, TX
Former Vice President EAA Chapter 1246
RV-9 (yes) N369RV
Mattituck IO-360, C/S Whirl Wind Prop, GRT, Digiflight II, Garmin SL30 & GTX 330 and Hotel Whisky Aux tanks, Bla Bla Bla
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  #34  
Old 02-07-2020, 04:05 PM
weissfamily97 weissfamily97 is offline
 
Join Date: Jun 2017
Location: Kansas City, MO
Posts: 20
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Quote:
Originally Posted by guccidude1 View Post
Stop dreaming and put in an IO-360, fixed pitch Sensenich 72 x 85. It wil cruise at 155 kts, 8.5gal/hr at 10.5 alt. LOP at same altitude 7.2 at 143 kts and no wind, Mr. Dynon will says 27.2 kts/gal. Less than 10 kts of wind, that's how I lean, 27 kts/gal plus or minus. Dan from Reno
These are interesting numbers.
I would have thought you'd see much more speed.
It'd be great to get everyone's numbers for comparison.
I have an O-320.
I see (and plan) 152kts, WOT, 8GPH, ROP at 8000.
CHT does seem to run a bit hot though...
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  #35  
Old 02-07-2020, 04:33 PM
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N941WR N941WR is offline
 
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One thing that I really like about modern EFIS's (EFII?) is that they calculate Vne in TAS while you are flying and let you know as you approach it. As for the Vno, I will have to see if it moves the next time I fly, I really don't recall if it changes but I kind of doubt it will.

Scott is correct in that a 180 hp -9 can run in the yellow without pausing. However, as you climb, it becomes more and more difficult to do so, as pointed out.

If you elect to go with a 360, just watch your speeds.
If you elect to go with a 320, you will still have a great aircraft that runs at the same speeds most of us with 360 run and because in the end, we are more impressed with low fuel burns than high cruse speeds and high fuel burns.

I second the comment about the -9's wing, it is just amazing! (Someday, I would like to hear why that airfoil wasn't used again.)

Back when I had my O-290d2 in my -9, I would fly whit the gang that eventually became Team RV and later Team Aerodynamics. A bunch of us took a 160 NM trip from Charlotte, NC to 12VA (middle Virginia). I took off first and by the time I entered the pattern, the last of the "fast" planes were just touching down. You really have to take a LONG trip for a few extra knots to make much of any difference and even with that little engine, I could easily climb at well over 1400 FPM, if I needed to.
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RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
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SC86 - Easley, SC
www.repucci.com/bill/baf.html

Last edited by N941WR : 02-07-2020 at 05:03 PM.
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  #36  
Old 02-07-2020, 04:54 PM
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RV8JD RV8JD is offline
 
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Quote:
Originally Posted by N941WR View Post
One thing that I really like about modern EFIS's (EFII?) is that they calculate Vne in TAS and adjust the Vno line while you are flying.
I think you meant "Vne" instead of "Vno".

The pic in Post #29 illustrates that feature (for RV-8s and -7s).
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Carl N.
Arlington, WA (KAWO)
RV-8, 660 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasflügel Standard Libelle 201B - Sold
Rolladen-Schneider LS1-f - No longer owned
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  #37  
Old 02-07-2020, 05:02 PM
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N941WR N941WR is offline
 
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Quote:
Originally Posted by RV8JD View Post
I think you meant "Vne" instead of "Vno".

The pic in Post #29 illustrates that feature (for RV-8s and -7s).
No, the SkyView calculates the Vne based on altitude and temperature. I think the Vno stays the same, but need to verify it. I'll change my post.

Thanks for point that out.
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Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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  #38  
Old 02-07-2020, 05:07 PM
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RV8JD RV8JD is offline
 
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Quote:
Originally Posted by N941WR View Post
No, the SkyView calculates the Vne based on altitude and temperature. I think the Vno stays the same, but need to verify it. I'll change my post.

Thanks for point that out.
You are correct, Vno stays at the same IAS. Vno is only a function of IAS (or really, CAS). Maybe I misread your post, it's a little ambiguous. When Vne is input as a TAS value limit, Vne (Redline) is dynamically calculated in terms of IAS based on Altitude and OAT, and is displayed on the IAS speed tape.

The Vno line is never changed from its IAS value, which your post seemed to imply.

As an example, for the RV-8s and -7s, Vno = 193 MPH IAS and Vne =230 MPH TAS. In my SkyView Touch I have the Vne Redline limit input in terms of TAS. In the screenshot below, at 9,800' with an OAT of 36 Deg F, Vne = ~196 MPH IAS as indicated by the Redline. Note that Vno is always 193 MPH IAS.



Sorry for the confusion.
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Carl N.
Arlington, WA (KAWO)
RV-8, 660 Tach Hours
(Pic 1),(Pic 2)
- Out with the Old, In with the New
(Pic)
RV-8, 1938 Tach Hours (Pic 1),(Pic 2) - Sold

Glasflügel Standard Libelle 201B - Sold
Rolladen-Schneider LS1-f - No longer owned

Last edited by RV8JD : 02-12-2020 at 06:18 PM.
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  #39  
Old 02-12-2020, 12:50 PM
georgedouglas georgedouglas is offline
 
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I started this thread and was wondering the pros and cons of increasing the compression in my 160 HP 0-320 while I am rebuilding the engine. It most likely is 8.5 compression presently.
george
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  #40  
Old 02-13-2020, 08:44 AM
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airguy airguy is offline
 
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Quote:
Originally Posted by georgedouglas View Post
I started this thread and was wondering the pros and cons of increasing the compression in my 160 HP 0-320 while I am rebuilding the engine. It most likely is 8.5 compression presently.
george
You can burn lower grade fuels with that compression if that's an attraction for you.
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N16GN flying 560 hrs and counting! Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.
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