Not Just Another 7 vs 9 Thread

[StuBob]

Originally Posted by ChiefPilot

Not going to get into the debate, but will point out that the difference between the 7/9 in terms of cruise efficiency is fairly small, and easily overshadowed by other factors such as attention to drag details and even how the aircraft is operated.

Also overshadowed by an extra 6 gallons of fuel.

[ChiefPilot]

Originally Posted by N941WR

Let's see a short wing RV do this:

The video I posted shows the short wing RV going 5kts faster on 5.8GPH. That's pretty close - and there is no doubt the short wing could slow down while the long wing may or may not be able to speed up. Not sure what your point is, other than going slower burns less fuel. You got me there

Anyway, my point is that efficiency is the result of many things. The higher aspect ratio wing is certainly more efficient, but it's pretty minor compared to other factors.

[rockwoodrv9]

Originally Posted by ChiefPilot

The video I posted shows the short wing RV going 5kts faster on 5.8GPH. That's pretty close - and there is no doubt the short wing could slow down while the long wing may or may not be able to speed up. Not sure what your point is, other than going slower burns less fuel. You got me there

Anyway, my point is that efficiency is the result of many things. The higher aspect ratio wing is certainly more efficient, but it's pretty minor compared to other factors.

Ground speed of 162 against 210. Of course wind and everything else matter. At least that is how I read the panel indications. Im still finishing mine up and planning my license check ride cross country in a 172 so these numbers are not even in my range of thought!

Im sure either would be great. I can't wait to find out how much more fun it is flying my 9A than the 172!

[PilotjohnS]

Originally Posted by rockwoodrv9

Im sure either would be great. I can't wait to find out how much more fun it is flying my 9A than the 172!

Me either. But by the time I am flying, not sure if I will remember how chunky a 172 was.

[Dugaru]

Having moved from a Warrior to a -9A, let me just say: prepare to grin.

Oh. My. God.

Originally Posted by rockwoodrv9

Im sure either would be great. I can't wait to find out how much more fun it is flying my 9A than the 172!

[Airzen]

In addition the rv-9 is in a slight descent. VSI shows -50.

Originally Posted by ChiefPilot

The video I posted shows the short wing RV going 5kts faster on 5.8GPH. That's pretty close - and there is no doubt the short wing could slow down while the long wing may or may not be able to speed up. Not sure what your point is, other than going slower burns less fuel. You got me there

Anyway, my point is that efficiency is the result of many things. The higher aspect ratio wing is certainly more efficient, but it's pretty minor compared to other factors.

[bret]

Both are similar in cruise, but coming down from altitude in the 7a it is nice to do 190-200 KTAS in calm air and

[Bevan]

A trip to Alaska is but one (albeit a great one) use of an airplane. While the differences are minimal, your decision may be better based on what else you plan to do with the plane.

For me, my decision was for the 7 due to the additional strength of the wing (occasional aerobatics and mountain turbulence), more speed and the landing speed was low enough to not warrant the 9. The issue of slightly less stability of the 7 (slightly more neutrally stable make the 7 more fun like a fighter), can be eliminated with an autopilot. I do not regret my choice of 7 whatsoever, however both are great choices. Kinda like splitting hairs here.

Bevan.

[N941WR]

Originally Posted by ChiefPilot

The video I posted shows the short wing RV going 5kts faster on 5.8GPH. That's pretty close - and there is no doubt the short wing could slow down while the long wing may or may not be able to speed up. Not sure what your point is, other than going slower burns less fuel. You got me there

Anyway, my point is that efficiency is the result of many things. The higher aspect ratio wing is certainly more efficient, but it's pretty minor compared to other factors.

I was throttled back for that flight to extend my range.

My point was, the short wing RV's don't perform as well up high as the -9 with that wonder Roncz airfoil does.

The few gallons difference between the two isn't enough to worry about and if you are planning on long range flights, you can always added additional capacity.

[N941WR]

Originally Posted by Airzen

In addition the rv-9 is in a slight descent. VSI shows -50.

(rolling eyes)

Would you like to see the picture with a slight climb? The speeds are virtually the same.