RV-7 / RV-9 Aerobatics - Extra Fuel

skyfrog · #1 12-13-2006, 06:01 PM

My appologies, but I'd like to ask a couple more question on the RV 7/9 difference.

Since I passed my medical on Monday, I've given up the RV-12 idea. (Phew!)

My first question is one of aerobatics. To those RV-7 owners out there, can you give me a rough percentage of the time you use the aircraft for aerobatics? Every weekend? Once a year?

My second question is the possibility of having extra fuel on an RV9. The RV7 has extra fuel. I plan on getting the QB wings, so the mod to the fuel tanks is not an option. Is there a possibility of a baggage compartment fuel tank or wing tip tanks in the future for the RV9? Range is important.

My main "mission" is to fly cross-country several times a month, so the RV9 seems perfect. However, I get the urge now and then to push the envelope.

What I really need is a test flight in each. But how? I guess I'll wait for Sun-N-Fun in Lakeland before ordering.

Thanks,

John Edwards
Tools in place
EAA Workbench built
Ready to Order

Kyle Boatright · #2 12-13-2006, 06:45 PM

I'm an RV-6 owner, but the -6 and -7 are virtually identical. I will tell you that I do numerous rolls, wing overs, split S's, and maybe a loop or two almost anytime I'm solo in the airplane, which is 90% of my flights.

The other 10% I'm flying cross country with baggage and/or passengers and don't do acro.

skyfrog · #3 12-13-2006, 07:08 PM

Thanks Kyle,

That's just the input I was looking for...

John

Low Pass · #4 12-13-2006, 07:36 PM

Quote:

Originally Posted by skyfrog

My appologies, but I'd like to ask a couple more question on the RV 7/9 difference.

Since I passed my medical on Monday, I've given up the RV-12 idea. (Phew!)

My first question is one of aerobatics. To those RV-7 owners out there, can you give me a rough percentage of the time you use the aircraft for aerobatics? Every weekend? Once a year?

My second question is the possibility of having extra fuel on an RV9. The RV7 has extra fuel. I plan on getting the QB wings, so the mod to the fuel tanks is not an option. Is there a possibility of a baggage compartment fuel tank or wing tip tanks in the future for the RV9? Range is important.

My main "mission" is to fly cross-country several times a month, so the RV9 seems perfect. However, I get the urge now and then to push the envelope.

Congrats on passing the medical exam!

If I were doing extra fuel, I'd put it in the wingtips only then derate the max load factor accordingly. IMVHO, fuel tanks in the fuselage should be avoided if at all possible.

As for RVs and acro, I cannot conceive of *any less* than 90% of my flights allowing me to look through the top of the canopy at the earth.

skyfrog · #5 12-13-2006, 08:22 PM

I did not expect a 90% acro profile...

I need to do some rethinking on my kit choice.

John

n468ac · #6 12-13-2006, 08:49 PM

If i go alone ... upside down i go

Spindrift · #7 12-13-2006, 08:56 PM

Hi John,

I faced the same choice, and as a newly minted PPL, I didn't have the experience to base it on. I did a demo flight in Vans RV9A, then took a ride in a friends RV6A, but couldn't tell the difference other than they were both WAY better than the C152 I was used to. So, to resolve the issue so I could get started, I ponyed up the bucks for an acro lesson and I was hooked on the first loop! While I'm still only finishing the tail and have a couple years before my QB 7A is flying, I'm already looking forward to frequent 'gentlemans' acro most everytime I'm solo.

bill
RV7A, waiting for a new trim tab hinge so I can finish the tail...

N941WR · #8 12-13-2006, 08:58 PM

Quote:

Originally Posted by skyfrog

My second question is the possibility of having extra fuel on an RV9. The RV7 has extra fuel. I plan on getting the QB wings, so the mod to the fuel tanks is not an option. Is there a possibility of a baggage compartment fuel tank or wing tip tanks in the future for the RV9? Range is important.

My main "mission" is to fly cross-country several times a month, so the RV9 seems perfect. However, I get the urge now and then to push the envelope.

John,

The fuel capacity difference is only an issue if you are looking a -7 & -9's with the same engine. i.e. O-320. If the -7 is powered by an 180-200 hp I/O-360 then the extra power will eat into your fuel. IMHO, the -9 has the right amount of fuel for the engine size it is designed for.

As for the acro issue, as you know the -9 is not designed for it but I do know of one local -9A that has just been looped and rolled with no ill effects. Your mileage (and pilot) may very.

dan · #9 12-13-2006, 09:34 PM

Quote:

Originally Posted by N941WR

If the -7 is powered by an 180-200 hp I/O-360 then the extra power will eat into your fuel.

Don't believe the hype. My 200hp IO-360 burns less fuel than any RV-9[A] I've flown next to at any airspeed. My "fuel guzzling" RV-7 out-climbs, out-cruises, out-economizes, and out-ranges any RV-9[A] at any speed. Don't believe the hype. Bigger engine doesn't have to translate to higher fuel consumption!

My normal wide-open-throttle cruise fuel burn is 7.2 - 7.4 gph at 170 KTAS. I continually ask RV-9[A] guys about their fuel burn and cruise speed, and it's almost always in the 8.5 gph at 155 KTAS region. And that's comparing my 200hp IO-360 to their 160hp O-320.

The only thing at which the RV-9[A] can beat my RV-7 hands down is glide ratio and stiffness of control...

donahuedc · #10 12-14-2006, 06:03 AM

John,
It wasn't long ago that I had to make the same decision. Since I haven't had the opportunity to fly either model, my advice is worth what you're paying for it.
I was trying to decide between a 7a and 10. I went to a little RV fly-in and looked and talked to builders. I saw a 9a and briefly talked to the the owner just to ask why he decided on this model. He told me that he had previously built a 6 and sold it. He said that the 9 was the best airplane Van has made. Before that, I really hadn't considered a 9.
So I really started thinking seriously about what i wanted the airplane to do. And the 9 fit the bill for me. I want a weekend flyer that I can take trips in. My mission includes several trips to the Bahamas, so the glide ratio of the 9 is a psychological comfort for me.
As far as aerobatics, I've done them and didn't find them such a thrill that I would be doing them every time I fly. But this is something that you have to figure out for yourself. My impression is that the hardcore aerobatics types build a 3,4,or 8 (or a Pitts). The hardcore aerobatics types with a wife build the 7 (or 6). The rest can see the merits of the 9 or 10. Having said this, I really don't think you can make a bad choice. I think you'll love whatever you build.
As for the extra fuel. I think I might also want extra fuel for my long trips. Are wing tanks safer than a fuselage tank? Probably... But I currently fly a J3 cub with the fuel between the engine and my knees. It amuses me when I hear someone worry about a fuselage tank who regularly does low passes. (This is not meant as a criticism of anyone here. I knew a pilot who died from a low pass with trees at the other end. Before you think that you're better than that, I have to tell you that he was a former aerobatic champ. It just takes one mistake. Ask yourself if you think you're perfect. I've already answered this question for myself.) So what I'm doing is building stock. Then after flying for a while, if I find that I really do want extra fuel, I'll add a removable tank in the baggage compartment. Use it for the really long trips. Take it out when I don't need it.