Performace RV-7 VS. RV-9

[stefan87]

Hi,

I am an RV builders from Europe from Austria.

I would be interested in the following of you very much:

Motorized How you at? (O-320, IO-320, O-360, IO-360 (180HP, 200HP)
How are your climbing performance?
What are the cruise performance?
And what is the consumption?

I have heard that the RV-7 (180 HP) in the cruise should be almost equal as an RV-9 (160hp). Is that true?

Yours sincerely,

Stefan

[Andy Hill]

Stefan...

The Van's website will probably give you the best, unbiased figures - see RV-7 Perf and RV-9 Perf

Personally, I would think the "performance" values do not differ by a significant amount, and if you are choosing between the 2 types, other capabilities e.g. aerobatics / short field might be more relevant comparisons

Andy

[stefan87]

Yes on the homepage of Vans

There are specified performance values,

But how far can one believe them?

Yours sincerely

Stefan

[hydroguy2]

Originally Posted by stefan87

........But how far can one believe them?......Stefan

Vans numbers are probably more believable than numbers from somebody you've never met posting on a internet forum.

[N941WR]

Originally Posted by hydroguy2

Vans numbers are probably more believable than numbers from somebody you've never met posting on a internet forum.

Van's is known for putting out "real" numbers.

[hydroguy2]

Originally Posted by N941WR

Van's is known for putting out "real" numbers.

That's what I was trying to say. You can believe Vans numbers as long as you build it per plans

[mculver]

One thing that doesn't appear in Van's numbers though is performance at other altitudes. My impression is that the 9 has an airfoil that really rocks above 8,000 ft -- more like 14,500 or so.

Accordingly isn't it more a question of whether or not you are interested in aerobatics or cross-country?

[L.Adamson]

Originally Posted by mculver

One thing that doesn't appear in Van's numbers though is performance at other altitudes. My impression is that the 9 has an airfoil that really rocks above 8,000 ft -- more like 14,500 or so.

Accordingly isn't it more a question of whether or not you are interested in aerobatics or cross-country?

A few realities. First off, I don't fly my 6A at 14,500 as a normal crusing altitude. Usually, the highest is 12,500, and several times at 13,500. We do have oxygen. I haven't been along or flew a 9 at 14,500 either, but a friend has had his 9 to 17,500 msl.

A reality I'm mentioning is cross-country. I've flown two different 9A's, and the 9A drivers have flown mine. Something we all agree on, is that if you're sitting in the 9A or 6A blind folded in either smooth or turbulent air.......you'd be hard pressed to know the difference. They both fly smooth, and they both bounce just as bad. The 9 does have a slower landing speed, as well as descent rate. That could be an advantage is certain cases. Both the 9A and 6A will come down like a rock with a constant speed prop acting as an airbrake. Both the 6A & 9A with constant speed props will fall out from underneath you if you allow it in the flare. At a certain point around stall speed, the airspeed quickly diminishes with a C/S...........so watch for it!

So now it's down to mild aerobatics or lower landing speeds. About 10 mph worth. Of course, I'm I'm talking 6A, but Van's spec sheet shows them as being very close performance wise.

L.Adamson --- RV6A

[videobobk]

Stefan,

I fly a 160 hp 9A and took training in a 180 hp 7. They fly very similar to each other. I know the 7 was a little faster at the lower altitudes, but they are about equal at 8000'. Perhaps a bit faster higher up the 9A is faster, but we haven't tried that. The 9 airfoil and longer wing loves altitude!

As mentioned, you probably should decide based on flying needs, not speed. There will be only a few kts difference at any altitude. If you want aerobatics, go with the 7. If short field work, lower landing speeds, or instrument flying is important, the 9 may be slightly better.

Climb is about the same. You can't make a bad decision here!

Bob Kelly

[N941WR]

Originally Posted by hydroguy2

That's what I was trying to say. You can believe Vans numbers as long as you build it per plans

Brian,

Sorry about that, I was trying to reinforce your earlier comment. In a way, it will be a bummer I won't have a CS prop because it would be cool to go up to the teens with a 180 hp RV-7 and do a real time comparison.