More on the 7 vs 9 question

[SlowJoe]

I am a student pilot, and am hoping to order a tail kit soon. I've read pretty much every thread on the 7 vs 9 question. But I still can't make up my mind. Since I am very low time, there are some things about the nine that appeal to me. However, by the time I get her built, I'm sure I will be much more experienced as a pilot.

My question is how the 7 and 9 compare to the DA 20 I am training in. In the pattern, I pitch for 80 and put in the first notch of flaps. After I turn final, I pitch for 75 and put in the final notch of flaps and maintain this speed until I flare for landing.

How does this compare to the speeds for the 7 and 9? I know the 9 has a lower stall speed, but what I want to know is what do you fly your approaches at. Is the 7 a lot "hotter"?

Also, I've heard people say the DA 20 is like a glider. How does it compare to the wing on the 9. People say the 9 "floats" a bit. Is it similar to the Diamond?

Finally, will the 9 with a 360 keep up in cruise with the 7's with 360's?

Thanks

Joe

[n5lp]

Originally Posted by SlowJoe

I am a student pilot, and am hoping to order a tail kit soon. I've read pretty much every thread on the 7 vs 9 question. But I still can't make up my mind. Since I am very low time, there are some things about the nine that appeal to me. However, by the time I get her built, I'm sure I will be much more experienced as a pilot.

My question is how the 7 and 9 compare to the DA 20 I am training in. In the pattern, I pitch for 80 and put in the first notch of flaps. After I turn final, I pitch for 75 and put in the final notch of flaps and maintain this speed until I flare for landing.

How does this compare to the speeds for the 7 and 9? I know the 9 has a lower stall speed, but what I want to know is what do you fly your approaches at. Is the 7 a lot "hotter"?

You talk about your speeds but give no units. The only DA20 I have flown had an airspeed indicator that showed knots. If that is what you are using, it sounds like you are flying final at far faster speeds than any RV would typically use. I have an RV-6 and fly final at 60 to 65 knots depending on weight and gustiness. An RV-9 would typically use a speed around 5 knots slower.

Also, I've heard people say the DA 20 is like a glider. How does it compare to the wing on the 9. People say the 9 "floats" a bit. Is it similar to the Diamond?

The DA20 glides much better than a 6 or 7 and better than a 9 also. It has a much higher aspect ratio wing. It has been my experience that the RVs and the DA20 do not float if the proper speeds are used. If you are fast, the DA20 is less forgiving of that than the RVs would be, particularly an RV with a constant speed prop. A constant speed prop has a large braking action that lets the airplane decelerate quickly even when an excessive approach speed is used.

Finally, will the 9 with a 360 keep up in cruise with the 7's with 360's?

Everything else being equal, no, but the difference is not huge.

[N941WR]

Originally Posted by SlowJoe

I am a student pilot, and am hoping to order a tail kit soon.

Great! Build the -9. It will take you a number of years to complete and if you are like most pilots, you won't have time or money to fly while building.

Once you have it done, get current, fly the -9 for a few years and then, if you want to do acro, sell the -9 and build a -7 (or -8, or -4, or -3).

Originally Posted by n5lp

Everything else being equal, no, but the difference is not huge.

It depends at what altitude you are flying. The higher you go, the more efficient the -9 is. Again, the difference is not huge.

Also, the -9 will jump off the ground but and this is big BUT, if you build a heavy airplane, be it a -7 or a -9, all bets are off on all performance measures.

Get a ride in both, don't make up your mind based on something you read on the net. This is a costly decision; make the right one up front.[/quote]

[Greg Arehart]

I've rarely had an issue with float on the 9, though it certainly does not sink quite as fast as a 6 or 7. Generally the 9 is slightly slower than the 7, but not by much. And it depends on altitude and prop pitch. I can get right at 200 mph out of my 9 (burning a lot of fuel) and easily cruise at 165-175 mph true on 6-8 gph (depending on altitude). I have FP prop pitched for cruise, since that's where I spend most of my time. The 9 is also a bit less twitchy than the 6 or 7 (i.e., feels a bit more stable) IMO.

I agree, try to get a ride in both and maybe a half hour or more of stick time to see the difference. It is very much a personal decision.

cheers,
greg

[JDRhodes]

Student pilots can get all uptight about getting a permanant airplane that is "most like the xxxx-trainer that I've been flying."

Really, I doubt you WANT something that flies like a trainer. None of the RVs are at all difficult to fly. I wouldn't factor your training airplane's characteristics into the equation. Get waht you want for the reasons you want it. Get some transition training, and you'll be fine whatever you pick.

[Andy Hill]

In practice RV-7 and -9 do not differ greatly.

However, if you have not decided between the 2 and ask:

Finally, will the 9 with a 360 keep up in cruise with the 7's with 360's?

why conisder a 360? And go directly against the manufacturers' recommendations?

If speed / can I keep up are so high in your priorities then build the one designed for that. Are you really sure at your stage you do not wish to fly, or even try, aerobatics / tailchasing? Build a 9 and you are committed to that...

In short, IMHO the 9 is great for those who know what want, and more importantly what they do not want. Unless you are in that situation, I would build the 7 - well, no I would build an 8 (again ) - it is an "all rounder" and the 9 only beats it in the 9's special areas to a small degree.

Andy & Ellie Hill
RV-8 G-HILZ
RV8tors

[apkp777]

I built a -9. I did so purely on economy and no desire for inverted attitudes. I don't care what people tell you, an o-320 is more fuel efficient than an o-360, ignore anyone who talks about "throttling back", it's hogwosh.

Here are some FACTS about a -9,
1. Cheaper to build than a -7.
2. Great performance, but not as good as a -7
3. Slightly better stability in roll, the same in pitch than a -7
4. Better fuel economy (don't put a 360 in a -9, build a -7 if you must do that)
5. Just as easy to fly as any other RV. Easy to land, but also easy to botch if your not careful.

Ask yourself these questions:

1. Do I want to go inverted? Yes, No or Maybe? A yes or maybe= -7
2. Will I be satisfied with 150KTAS cruise? Yes, No or Maybe? A yes or maybe= -7 or -9. A "no" = -7
3. Can I afford the extra build cost for the -7 (yes, a -7 will cost more)? Yes or No? A no = -9, yes=-7 or -9

[Jamie]

Originally Posted by apkp777

1. Cheaper to build than a -7.

How is that exactly? Given the same equipment they are almost exactly the same price. Actually the -9 kit is currently $500.00 more than the -7.

[apkp777]

Originally Posted by Jamie

How is that exactly? Given the same equipment they are almost exactly the same price. Actually the -9 kit is currently $500.00 more than the -7.

Jamie, I suppose if you put a o-320 in a -7 you could build them for about the same, however no one does that. It's my guess that if you averaged the build costs for -9's and -7's the average -7 is $5k to $10k more.

Most people building a -7 do so for the extra performance. So adding an 360, perhaps C/S prop, injecting it, add 5 point harness, any inverted systems all would be typical added expenses. Of course you could add all that to a -9 as well, and a cessna 152, but defeats the original intent.

I don't thinks it's a fair comparison, a low performance -7 and a high performance -9.

[prkaye]

I'm guessing the O-360 is significantly more expensive than the O-320?
I got my overhauled O-320 with new ECI cylinders from Aerosport Power a couple of years ago for under20k, all-said.