Hi all, new member, 7 vs. 9

John Silver · #1 04-23-2005, 05:23 PM

Hi all. New member here. I'm interested in building an RV-7A or 9A, haven't decided which yet. Mission is wife and I go to visit grand kids 1,000 miles away about 4 times a year, and $100 hamburger type Sunday excursions in between. Mostly grass fields both at home and at the hamburger locations. The plane would be IFR configured.

I like the 500 fpm glide capability and low stall speed of the 9A, and with a 160 hp 320 on both the 7A and 9A, performance is just about identical between the two, except for the stall speeds and G handling. No interest in aerobatics, but would like to know that in an emergency, if I needed to stress the plane, it wouldn't break.

Here's a question that'll probably get me some flak. Has anyone installed an air conditioner in their RV? I'd be very interested in an automobile type environmental system with auto temperature control, etc. I know it's extra weight, but I'd trade some performance for comfort. Feasible?

1911pilot · #2 04-23-2005, 07:32 PM

I called Vans when I had the same question, They put me through to Ken Kruegar. What it basically boiled down to was what do you was do you want to do aerobatics or do you want a stable cross country machine. I would love to do aerobatics every once in awhile, but I'd much rather take 3 day weekends once a month and go somewhere far away.

I'm taking the 9a myself, its not that much slower than the 7 and burns less fuel since its got a smaller engine. (Assuming your going for the 360.)

My 2 cents. Call Vans...

Jeff

n2prise · #3 04-23-2005, 08:58 PM

Just climb above the cloud layer and it gets cool enough. If you really insist on A/C for ground ops, you could have a problem with where to put the compressor and a belt drive for it without a custom cowl design. And then there is the weight of the compressor and the FAN to circulate the air through the evaporator inside the cabin. Plus, you will need more insulation to give the A/C a chance to do the cooling thing. Then last of all, you will really need to seal the cabin for air leaks to keep that cool air inside.

As far as the choice of the RV-9A over the RV-7(A), I chose the 9A for the lower landing speeds due to the longer wing span. It climbs faster than the 200 HP RV-6's, 7's, and 8's due to the lower span loading of the 9. The 9 has a 28-foot wing span, while the others check in at 23 feet.

The lower landing speed of the 9 will minimize the chance of breaking it. As for G-forces, it compares to a Cessna 172, not a Laser 300, Pitts, etc.

Jerry K. Thorne
RV-9A N2PZ

Captain_John · #4 04-23-2005, 09:03 PM

Quote:

Originally Posted by n2prise

The 9 has a 28-foot wing span, while the others check in at 23 feet.

Nope, the -7 has a 25' wingspan.

23' is the -8, as it has a narrower fuse.

If you wanna yank and bank, get the -7.

If you wanna cruise and look at the pretty leaves, get the -9.

Either way, you will be pleased!

CJ

Highflight · #5 04-24-2005, 07:25 AM

I haven't yet heard from anyone actually flying the -7 that it isn't a good Xcountry machine (you there, Roberta?) compared to the -9. The fuselages of the -7 and -9 are identical so ergonomic comfort is certainly the same between the two.

It seems to me that I wouldn't want to fly long Xcountry with either the -7 or -9 without an autopilot, and that with one, you wouldn't notice any difference other than than that you'd cover more ground faster in the -7.
Then, the only difference is that when you turn off the AP in the -7, you can let the fun begin.

The reason that an A/P is mandatory, in my opinion, is that I confess that in the few longer Xcountry's I've done in a 172 (without autopilot) that I would occasionally let my heading and altitude wander (just a wee bit) when I was busy with other things. Anyone who denies that they've done the same is either lying or has flown captain on the Space Shuttle.

One more thing as to why I went with the -7; I have personally been hit so hard with shear that I could see the wings move on the 152 I was in, and I was truly concerned that the darn things might break. I'm talking about the kind of shear where loose objects dented the ceiling panel.
Even though I'm not big into airbatics, I rather like the idea of my Xcountry aircraft being able to withstand potential momentary stresses of cosmic forces.

It appears that the only significant advantage to the -9 is it's slower stall speed due to the Roncs airfoil, so if that's a big issue, then one would have to go with the -9.
For perspective, though, the stall speed of the -7 is only 4mph higher than a 172 w/full flaps, while the -9's stall speed is the same as a 152 w/full flaps. I've flown both, and I can't recall much "felt" difference at all in how they handle on landing.

Either way, you still spell fun; "RV".

Just thinkin' out loud.

L.Adamson · #6 04-24-2005, 08:02 AM

Quote:

Originally Posted by n2prise

As far as the choice of the RV-9A over the RV-7(A), I chose the 9A for the lower landing speeds due to the longer wing span. It climbs faster than the 200 HP RV-6's, 7's, and 8's due to the lower span loading of the 9. The 9 has a 28-foot wing span, while the others check in at 23 feet.

The lower landing speed of the 9 will minimize the chance of breaking it. As for G-forces, it compares to a Cessna 172, not a Laser 300, Pitts, etc.

Jerry K. Thorne
RV-9A N2PZ

As to climbing faster, I'm not so sure about that. The spec's from Van's website, list the 6,7, and 8 as all climbing faster at solo & gross weights with the 180/200 HP engine combo's, versus 160HP for the 9.

Without doubt, the 9A lands at a slower speed. Throttle off over the threashold seems to work everytime.

Since I once paid for aerobatic instruction in a Pitt's S2B for a couple of years, I still lean towards mild aerobatics. Just completing a 6A, since 7,8's, and 9's were not available at the time.

L.Adamson --- RV6A,180HP,C/Sprop

Build9A · #7 04-24-2005, 09:13 AM

If you don't mind having a 28 quart coleman cooler in your airplane, you can buy a $50 airconditioner to attach to the lid. Do a search for Coleman or coolaire or portable coleman air conditioner, etc. It's supposed to work with battery or off your power plug. Never heard of anyone using it in an RV, but it might work.

John Silver · #8 04-26-2005, 03:09 AM

Sounds like air conditioning is somewhat impractical...

Is it common/possible to fly with slider canopies open? I've searched and haven't found mention of it. Many years ago while doing summertime touch and go's, we would open a side window on our KC-135A's (no air conditioning either). Very windy and nav's would get a bit upset with charts flying around everywhere, but it did cool things down.

Jaypratt · #9 04-26-2005, 06:38 AM

If you start flying with other RVs you will be a drag if you can not keep up.
I have no 9 experience, BUT, I have flown a 150 hp and a 160 hp RV 8, and RV8a with my group of BCs and it is not fun not being able to keep up with every one.
If yours is a solo mission slow is ok.

Jaypratt · #10 05-02-2005, 06:52 PM

someone didn't jump on me for this one?
My RV8 160 hp, now owned by Rick Freeman, N82RV, is just as fast as the 180 HP RVs Turbo, Krash, Scorch, and others fly, but the clime out and catch up rate is slower for him. He has to run at 2500 rpm to do what we 180 constant speed guys do. and he burns more gas too. Solo he uses less because he is not trying to keep up.
Guys, I'm still trying to figure all this out. We just do not have any 9s flying with us.
I figure that when this happens, Gary, we will have to pull back more, ?