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-   -   Not Just Another 7 vs 9 Thread (https://vansairforce.net/community/showthread.php?t=157062)

PerfTech 01-31-2018 01:53 PM

I guess I need to get busy!!!
 
...Wow! Its only been about 4 hours since my last post in this thread, and
already I have nine e-mails expressing interest in the belt and harness kit or
mod I talked about. I am saving all the addresses so I can contact all the interested
parties, please keep them coming.
Thanks for your responses. Allan...:D:D

bret 01-31-2018 02:15 PM

Quote:

Originally Posted by PerfTech (Post 1236262)
...Wow! Its only been about 4 hours since my last post in this thread, and
already I have nine e-mails expressing interest in the belt and harness kit or
mod I talked about. I am saving all the addresses so I can contact all the interested
parties, please keep them coming.
Thanks for your responses. Allan...:D:D

I have a lot of your great products, care to share your idea, :rolleyes: got us wondering now, are the anchor point geometries inadequate?

PerfTech 01-31-2018 02:32 PM

Quote:

Originally Posted by bret (Post 1236272)
I have a lot of your great products, care to share your idea, :rolleyes: got us wondering now, are the anchor point geometries inadequate?

...Absolutely not! They are exactly where they should be to do the job they were designed to do.
What I have in mind will have them doing double duty if you will, without effecting their original
design in any way. I will post something soon with more information. Thanks, Allan..:D

Rick Meyer 01-31-2018 02:39 PM

In the RV7 vs RV9 debate, have you considered the RV14? It perhaps gives you the best of both worlds?

Raymo 01-31-2018 02:39 PM

Quote:

Originally Posted by N941WR (Post 1236208)
It helps if you read the manual:

Touche, Bill. I read and read and did not see that information.

StuBob 01-31-2018 03:05 PM

Quote:

Originally Posted by Rick Meyer (Post 1236279)
In the RV7 vs RV9 debate, have you considered the RV14? It perhaps gives you the best of both worlds?

I have, but you have to stop spending somewhere.

Rick Meyer 01-31-2018 03:54 PM

I certainly understand that. I am trying to decide between the 7,9, and 14. I am leaning towards the 14, but as of yet, still undecided. It is a large commitment of time and money and I would like to be confident in my decision. And also my wife says I suffer from analysis paralysis, and yep, I believe she is right!

rvbuilder2002 01-31-2018 04:01 PM

Quote:

Originally Posted by bret (Post 1236179)
Question for those that hit the canopy, do you have a 4 or 5 point harness, and how close were you to the canopy, almost 14 mod?

In my case both instances were with a 4 point harness. That is just one of the reasons I am a big advocate of 5 point harnesses in RV's

Adding the 5th point and adjusting its belt properly pretty much eliminates any vertical movement, so short of doing neg. G aerobatics, I don't see why anyone would need to add modifications to the belt system.

BTW, no one should be doing neg G without a secondary belt anyway.

BillL 01-31-2018 04:08 PM

Quote:

Originally Posted by StuBob (Post 1236290)
I have, but you have to stop spending somewhere.

Stein would be happy if you can stop spending at SteinAir.

bret 01-31-2018 04:24 PM

Quote:

Originally Posted by Rick Meyer (Post 1236310)
I certainly understand that. I am trying to decide between the 7,9, and 14. I am leaning towards the 14, but as of yet, still undecided. It is a large commitment of time and money and I would like to be confident in my decision. And also my wife says I suffer from analysis paralysis, and yep, I believe she is right!

You better get started tomorrow, that illness will add at least 4 years to your build! :D

PerfTech 01-31-2018 06:11 PM

Quote:

Originally Posted by rvbuilder2002 (Post 1236312)
In my case both instances were with a 4 point harness. That is just one of the reasons I am a big advocate of 5 point harnesses in RV's

Adding the 5th point and adjusting its belt properly pretty much eliminates any vertical movement, so short of doing neg. G aerobatics, I don't see why anyone would need to add modifications to the belt system.

BTW, no one should be doing neg G without a secondary belt anyway.

....The -4 Gs we did wasn't by choice, and even with the 5 point a regulation size man will still hit his head in a hard downdraft at speed. I tried it with the lap belt so tight it was extremely uncomfortable (Couldn't fly like that) and you can still hit the canopy. I will show this in a video demonstration shortly.
Thank, Allan..:D

rvbuilder2002 01-31-2018 06:57 PM

Edited
 
Quote:

Originally Posted by rvbuilder2002 (Post 1236312)
In my case both instances were with a 4 point harness. That is just one of the reasons I am a big advocate of 5 point harnesses in RV's

Adding the 5th point and adjusting its belt properly pretty much eliminates any vertical movement, so short of doing neg. G aerobatics, I don't see why anyone would need to add modifications to the belt system.

BTW, no one should be doing neg G aerobaticswithout a secondary belt anyway.

Edited above for clarity. I misassumed that what I meant was obvious.

Steve Melton 01-31-2018 07:07 PM

Quote:

Originally Posted by Rick Meyer (Post 1236310)
I certainly understand that. I am trying to decide between the 7,9, and 14. I am leaning towards the 14, but as of yet, still undecided. It is a large commitment of time and money and I would like to be confident in my decision. And also my wife says I suffer from analysis paralysis, and yep, I believe she is right!

you are doing the right thing to take some time to settle on the model. whatever the choice, if you make the right decision it will keep you happy for the long run.

N941WR 01-31-2018 09:08 PM

Quote:

Originally Posted by Rick Meyer (Post 1236279)
In the RV7 vs RV9 debate, have you considered the RV14? It perhaps gives you the best of both worlds?

The good thing is you can't go wrong with either of the three.

Building the -7 and -9 are pretty much the same. The -9 has a few more rivets to drive simply because it has a longer wing, which may add about an hour additional to the total build time. Other than that, the effort is the same.

The quality of the -14 kit is just stunning. So many more of the parts are pre-made. Go look at the difference in build time in hours and years between the 7/9 and the 14. It is definitely in favor of the -14.

Whichever you select, you will be convinced it is the best of the litter.

StuBob 02-10-2018 11:26 AM

Staring at the numbers, it's hard to tell what really matters. For instance, baggage. Van's lists the RV9 baggage capacity at 75# and the RV7 at 100#. How can that be, if they have the same fuselage? Perhaps it's a cg thing, assuming a smaller engine in the -9?

N941WR 02-10-2018 11:52 AM

Quote:

Originally Posted by StuBob (Post 1238500)
Staring at the numbers, it's hard to tell what really matters. For instance, baggage. Van's lists the RV9 baggage capacity at 75# and the RV7 at 100#. How can that be, if they have the same fuselage? Perhaps it's a cg thing, assuming a smaller engine in the -9?

That's been a point of contention for so time. My builder manual lists 100 lbs and my CG allows for it.

I'm not sure when or why it was changed to 75 pounds. Scott?

RVbySDI 02-10-2018 05:30 PM

Quote:

Originally Posted by StuBob (Post 1238500)
Staring at the numbers, it's hard to tell what really matters. For instance, baggage. Van's lists the RV9 baggage capacity at 75# and the RV7 at 100#. How can that be, if they have the same fuselage? Perhaps it's a cg thing, assuming a smaller engine in the -9?

100# baggage limit in my RV9A with 1800# gross. CG within Van's specified limits. No realistic way to exceed the CG fore or aft.

bruceh 02-10-2018 07:36 PM

Quote:

Originally Posted by RVbySDI (Post 1238562)
100# baggage limit in my RV9A with 1800# gross. CG within Van's specified limits. No realistic way to exceed the CG fore or aft.

Same here. Even after painting, which moved the CG aft more, I can't get out of CG range unless the pilot (me) weighs about 40 pounds and I'm on empty fuel load (with full 100 pounds of baggage).

alpinelakespilot2000 02-10-2018 08:49 PM

Quote:

Originally Posted by StuBob (Post 1238500)
Staring at the numbers, it's hard to tell what really matters. For instance, baggage. Van's lists the RV9 baggage capacity at 75# and the RV7 at 100#. How can that be, if they have the same fuselage? Perhaps it's a cg thing, assuming a smaller engine in the -9?

It is simply a c.g. thing. Been confirmed through vans multiple times and has been documented in archives here on VAF. My cg with 0320 Catto prop and 4# crush late allows 100# in all configurations.

Doug Eves 02-14-2018 10:06 PM

I learned about the unsuspecting violent turbulence while flying my solo cross country in a 172 earning my PPL long ago. Beautiful day , nice and smooth ,then almost got my neck broke. Luckily stayed conscious or I wouldn't be here. Going to put 5 point in my 6 when I pull it down to put my autopilot in. Should have done that long ago. OH , almost forgot....I would just buy a really clean 6. (with a 7 cowl) Wouldn't trade mine for any of them

Mark_H 06-04-2018 10:53 AM

So...are you 6 and 7 guys saying the 9 wing is NOT more efficient up high?

PerfTech 06-04-2018 11:25 AM

Quote:

Originally Posted by Mark_H (Post 1264666)
So...are you 6 and 7 guys saying the 9 wing is NOT more efficient up high?

….The 9 is far more efficient everywhere! Go on Flight Aware, search
N-91AN, Look at my flights in track logs. It is vary rare to see speeds
less than 200mph once in level cruise at any altitude. Up high is a bit
better with far less fuel consumption. Thanls, Allan

Mark_H 06-04-2018 12:23 PM

I'm not asking what the 9 guys are saying. I'm asking what the 6 and 7 guys are saying. Are they calling BS on Vans 9 assertions?

airguy 06-04-2018 02:22 PM

Quote:

Originally Posted by Mark_H (Post 1264700)
I'm not asking what the 9 guys are saying. I'm asking what the 6 and 7 guys are saying. Are they calling BS on Vans 9 assertions?

In the first place, if they are flying a 6/7 and not a 9 then they really don't have any basis to do so.

In the second place, who cares? Build and fly what you want - those other people don't pay your bills and you don't have to care what they think.

Mark_H 06-04-2018 03:17 PM

I'm in the market for a side by side so yeah I have a personal interest. I'd really like to know what the true performance comparisons look like. On here, to listen to the 6/7 guys there is zero or negative advantage to 9 efficiency. So...are they really pedaling that or is it just my toy is the best thing ever bs?

airguy 06-04-2018 03:46 PM

Quote:

Originally Posted by Mark_H (Post 1264736)
I'm in the market for a side by side so yeah I have a personal interest. I'd really like to know what the true performance comparisons look like. On here, to listen to the 6/7 guys there is zero or negative advantage to 9 efficiency. So...are they really pedaling that or is it just my toy is the best thing ever bs?

I'll tell you that I flight plan for 155 KTAS on 6.5-6.8 gph in the mid-teens running WOTLOP, and routinely see 22-24 nm/gal efficiency. That's my personal experience, some others see better and some worse. Most people don't like to cruise as high as I do so they don't get the full benefit of the wing on the 9. My cruise efficiency testing, and it's been pretty extensive with my plans for a RTW trip, show my best efficiency between 14,000 and 17,000. How does that compare to a 6 or a 7? Dunno and don't care - I didn't build one of those.

Down low and don't care about the fuel flow, sure it'll go 170 knots - but there's precious little of that type of flying in my typical missions. I'll boom up above 10,000' just to go 50 miles in the cool smooth air up there, because it's so easy to get there.

Mark_H 06-04-2018 04:06 PM

Quote:

Originally Posted by airguy (Post 1264743)
My cruise efficiency testing, and it's been pretty extensive with my plans for a RTW trip, show my best efficiency between 14,000 and 17,000. .

Having gotten that impression is why I'm thinking 9. Arguments from 6/7 crowd?

ChiefPilot 06-04-2018 04:37 PM

Quote:

Originally Posted by Mark_H (Post 1264753)
Having gotten that impression is why I'm thinking 9. Arguments from 6/7 crowd?

Same altitude is good for the short wing RVs. The aspect ratio / spanwise loading is only one factor in overall efficiency that can be reduced or even overcome by other factors. Carbed vs. FI, electronic vs. traditional ignition, fixed pitch vs. constant speed and so on all factor in. Attention to detail also plays a part - did the builder need to install louvers or other changes to increase mass cooling flow? If so, then you have more cooling drag vs. a tight baffle setup.

As posted much earlier in the thread, this is video from my RV-6A doing what others claimed a short wing RV couldn't do. 164 KTAS on 5.8GPH at 15,500MSL / 16880 density altitude.

https://m.youtube.com/watch?v=Vt_Xduuc1QU

Mark_H 06-04-2018 05:01 PM

So Vans did not create a superior high altitude cruising plane?

tomww 06-04-2018 05:21 PM

For my point of view. In practice I fly my 7 with a friend in his 9. The difference in our real world is not that great.

My take.

If you want to turn it upside down it?s a 7 you need. If you don?t then a 9 is probably best.

Obviously it has to be a vp taildragger with a tip up. Cos everyone KNOWS that?s the best combo. 😊😊😊.

Seriously, build what you want. If you build it light without loads of aerial and keep it clean and straight well maintained then you will love it.

Finley Atherton 06-04-2018 06:10 PM

Mark,

THIS POST quoting figures from Vans for the 14, 9 and 7 may be useful. (Note that apparently experience has shown better figures for the 14).

I built the 9 rather than the 7 for the better short field performance needed on my somewhat marginal airstrip.

Fin
9A

Mark_H 06-04-2018 06:38 PM

That link sounds like the last word.

Mark_H 06-04-2018 06:42 PM

Quote:

Originally Posted by tomww (Post 1264767)

Obviously it has to be a vp taildragger with a tip up. Cos everyone KNOWS that?s the best combo. 😊😊😊.

.

Pilot wife says the little wheel has to be in front. :(

Maybe that will be her plane to visit the kids 1274nm away and I'll buy a 3 for myself. :)


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