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  #1  
Old 07-17-2017, 01:15 PM
workky workky is offline
 
Join Date: Sep 2016
Location: Marietta, GA
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Default RV7-RV9

Hey guys, im a lurker, i dont even own an airplane, i suck

I was curious though. What makes a 7 stronger than a 9?

Me and a partner are kicking around the idea of purchasing one or the other, but cant decide which one

I like strong!!!, but really dont plan on doing any aerobatics at this time. I say that lightly. Because i could watch top gun and go out and do some rolls.

But why is the 7 stronger than the 9 or rated higher than the 9 in G's?

Like the corss country of the 9 but like the strength of the 7
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  #2  
Old 07-17-2017, 01:26 PM
MercFE MercFE is offline
 
Join Date: Sep 2014
Location: Maple Valley, WA
Posts: 236
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Different wing designs... One is built for aerobatics, the other cross country performance.

Doesn't make the 9 wing any weaker. It's just rated for normal flight.
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  #3  
Old 07-17-2017, 07:18 PM
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N941WR N941WR is offline
 
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Location: SC
Posts: 11,597
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The -9 has a longer wing and a different (longer) HS.

Unless you are into doing acro, the -9 is plenty strong. If there was an issue with the -9's strength, it would have cropped up by now.
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  #4  
Old 07-17-2017, 08:59 PM
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RVbySDI RVbySDI is offline
 
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"Strong" is not the right way to think about it. Both airplanes are plenty "strong". They do have different "missions" they are optimized for though. Which mission you wish to fly will make a difference in which you choose.
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  #5  
Old 07-17-2017, 10:02 PM
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Captain_John Captain_John is offline
 
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Don't listen to Bill. He has a 9...

There is nothig that a 9 can do that a 7 can't!

. CJ
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  #6  
Old 07-17-2017, 10:31 PM
alpinelakespilot2000 alpinelakespilot2000 is online now
 
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Quote:
Originally Posted by Captain_John View Post
Don't listen to Bill. He has a 9...

There is nothig that a 9 can do that a 7 can't!

. CJ
Except glide substantially farther when your engine fails and land 10 knots slower so that you are more likely to survive the ensuing off field landing!

Seriously, to the OP, this has been hashed out numerous times on this forum. Do an RV-9 vs RV-7 thread search and you'll have plenty of reading.
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  #7  
Old 07-17-2017, 10:42 PM
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CubedRoot CubedRoot is offline
 
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Like others have said here, the wings on the -7 and -9 are not necessarily "stronger" than the other aircraft. The -7 has a wing that is designed to maintain the flow across the top in higher G loading, so it can be flown at higher angles of attack and not loose the "stiction" of the airflow across the top of the wing. BUT... there is some drawbacks to this, like not being as efficient and more "draggy" than other wings. It's a trade-off to get a wing that can fly those higher G numbers.

On the -9 the wing is more of a laminar flow design. Its designed to have a very smooth airflow over the wing, and present a less draggy profile into the wind so its more fuel efficient. Essentially it could fly the same true air speed with less horsepower (and less fuel consumption) as its RV-7 sibling. The larger tail surfaces also combine to give it more positive stability which is highly desired for cross country flying.

They are both fantastic designs, but they are targeted for different missions.

The 7 if you want to go out and do gentlemans acro, as well as a decently capable cross country airplane.

The 9 if you don't really care about acro, but your main mission is a fast, slippery 2 seater for taking on cross countries and being more fuel efficient.

Both wings will give you the same margin of safety if you fly them in their designed envelopes :-)
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  #8  
Old 07-18-2017, 07:37 AM
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ChiefPilot ChiefPilot is offline
 
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Location: Twin Cities, MN
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Quote:
Originally Posted by CubedRoot View Post
The -7 has a wing that is designed to maintain the flow across the top in higher G loading, so it can be flown at higher angles of attack and not loose the "stiction" of the airflow across the top of the wing. BUT... there is some drawbacks to this, like not being as efficient and more "draggy" than other wings. It's a trade-off to get a wing that can fly those higher G numbers.
I've never really thought along those lines before. "Stiction", eh?

Bottom line is that the -7 airframe is, in fact, stronger. Opinions vary, but numbers don't lie: the -7 is rated to +4.4G at 1800lbs gross weight while the -9 is rated to +3.8G at 1750lbs. Drop it to 1600lbs, at the -7 is rated to +6G while the -9 is rated to 4.4G.

Unless you are doing aerobatics, that should have no practical bearing on your decision though. Both are good airplanes.
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Last edited by ChiefPilot : 07-18-2017 at 08:44 AM.
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  #9  
Old 07-18-2017, 07:43 AM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
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Quote:
Originally Posted by CubedRoot View Post
...The -7 has a wing that is designed to maintain the flow across the top in higher G loading, so it can be flown at higher angles of attack and not loose the "stiction" of the airflow across the top of the wing.
I've never seen anything from Vans that supports this claim.
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  #10  
Old 07-18-2017, 07:48 AM
TS Flightlines TS Flightlines is offline
 
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Location: Ridgeland, SC
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Default Mr Workky,

whats your mission? 7 has more fuel capacity, alittle faster () both fly great. I was on the fence about the 7/9 thing for about 2 years, and decided the extra fuel and alittle extra speed was a plus. Just need to finish it!

Tom
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