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  #111  
Old 07-28-2012, 09:36 AM
aerhed aerhed is offline
 
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Quote:
no more Vetterman exhausts
Well that's a bummer.
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  #112  
Old 07-28-2012, 03:11 PM
Cuben1 Cuben1 is offline
 
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Van really pushes light weight and lighter engines up front for the current batch of single and two RVs because that is what the airframes were originally designed for.

The current RVs are evolutions of the same basic RV6 configuration that was itself an evolution of the RV-4. The RV-4 was itself Vans effort to expand the RV-3 to a two seat configuration without losing the magic that makes the RV-3 arguably the best all around sport plane ever made (if you fit in it).

With the RV-3 Van went against aircraft design conventional wisdom and discovered a previously unexploited design sweet spot where a low aspect ratio, low wing loading Hershey bar wing, combines with a suitable airfoil and clean airframe produced and amazing blend of flight characteristics to produce a break through design that offered amazing performance.

Van then combined this with a reasonably simple to build, amazingly low cost series of airframe kits and the rest of history.

The downside is that if you stray too far from the sweet spot and a lot of the RV goodness that makes the plane so special becomes degraded and the limitations of the low aspect ratio, square planform wing begin to show themselves.

The RV6 airframe was sized and designed to a be a simple, sub 1000lb VFR sport plane designed around a Lycoming O-320 that had an electrical system and wooden fixed pitch prop and retained as much of the RV-4 goodness (greatness?) in a two place side by side configuration.

Of course, right from the start, people began stuffing bigger engines, heavy CS props, IFR instrument panels and autopilots that would make Bonanza owner proud along with heavy show quality paint jobs and luxury interiors into their RV-6.

These heavy, complex -6s still flew great compared to just about everything else in the air except another -6 (or -4 and -3) built light and simple the way Van intended it to be, but the structural margins were getting iffy as people started flying the -6 at or above the maximum published gross weight and routinely exceeded the max aerobatic weight doing aeros with two people on board

The follow on -7 airframe was more of an internal structure redesign of the -6 to upgrade of the structure for higher strength margins at the higher gross weights that -6s were actually being built at while at the time making the air frame parts more common across different models, cheaper to produce and easy to assemble.

Other than that, the -7 stayed very close to the original -6 aerodynamic concept and airframe sizing. Now you could safely stuff a big engine/prop combo and IFR package into the -7 and safely fly the aircraft with a reasonable payload but a heavy RV7 still flew like a heavy RV6 - great compared to just about everything else in the air except a -6 or 7 built light and simple.

The new RV-14 airframe is scaled up from the smaller -7 and uses an airfoil specially optimized for low aspect ratio/square planform wing concept to work at higher wing loading the original airfoil in an attempt to re establish the original Vans sweet spot in a larger, heavier airframe.

If they were successful, they may have produced a larger, more stable airframe that has enough control authority to provide the flight characteristics more in line with the original -6 and -4.

Then again, Vans may have went in the opposite direction and designed the -14 to make it more docile for older, and/or lower time pilots and it really is a fat boy RV-9, which would be a bummer.

Time will tell on that one because not many people other than Van's people have flown the plane yet to what the -14 is all about.

FWIW, to put things into perspective, the Extra 200 with an AEIO -360 has almost exactly the same empty weight as Van has published for the RV-14 and, while the Extra 200 is no longer competitive at the Unlimited class level of International competition aerobatics , it still remains a very maneuverable high performance airplane that is very fun and very rewarding to fly. In fact, the 200 flys so well that Extra recently put it back into production in response to customer pressure.

While weight is obviously an important parameter, airframe design and control authority are more important factors determining flight handling and characteristics than a 100 -200 lbs of added weight. It would be a mistake to assume that the -14 has inferior flight characteristics based on extrapolating the performance of a heavy empty weight -7, of which there are more than a few flying.

For my money, I would bet that the the -14 flys a lot like a -10 optimized as a two place, aerobatics capable Vans sport plane instead of as a 4 place cross country aircraft, which is not a bad thing.

As such, I would expect the -14 to be nicely stable in straight and level flight, have light sensitive controls with rapid, crisp response to even small control movements and enough control authority for fun aerobatics and maneuvering flight, and fly smoother through turbulence for enhanced real world cross country flying to make the -14 a better traveling plane due to a combination of more refined straight and level pilot workload and higher wing loading.

While the specs show some reduction in short field capability, that reduction is primarily relative to the other RVs. Vans published numbers for take of and landing performance of the -14 are outstanding in their own right compared to other aircraft and I would be willing to bet that, while the -14 gives away a bit short field performance to the other two place RVs, it more than makes up for a few hundred feet of take off and ground roll with improved flight characteristics in the pattern and lower landing workload.

It may also be designed for certification under the FAA's proposed new stream lined, multi tiered certification process which makes it more practical to certify small aircraft if the proposal is adopted.

With all of the pre engineered and fabricated systems and a pre punched fast build kit combined with high quality, cost efficient off shore air frame production capability, the jump to a factory series production aircraft is not much of a stretch and trend for prospective owners who want to fly more than build is to purchase and already flying RV, so there is a proven potential market for a factory RV.

From what has been published so far, the level of design, analysis and documentation that Van's has put into the -14 seems to be extensive and professional enough to meet formal certification requirements. All that may be required is more extensive follow on testing and validation.

Last edited by Cuben1 : 07-28-2012 at 03:52 PM.
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  #113  
Old 07-28-2012, 03:30 PM
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KTM520guy KTM520guy is offline
 
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Quote:
Originally Posted by aerhed View Post
Well that's a bummer.
If you want a Vetterman exhaust then put one on. It's a homebuilt, you can do what you want.
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  #114  
Old 07-28-2012, 04:19 PM
aerhed aerhed is offline
 
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I just meant that Vans and Vetterman have been hooked together so long. You hate to see a cute couple drift apart.
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  #115  
Old 07-28-2012, 08:06 PM
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For anyone that hasn't seen the RV14 for themselves, I have a funny story:
Come to find out, last month when we were in Aurora, we not only saw it, but watched it taxi and takeoff from only about 80'. We were packing the airplane on the ramp and watched the Vans RV8A and what we thought (didn't think twice) was a blue and white RV7A taxi out and do an ok two ship departure to the north. Joe was at the controls of the '-7A'. I waved as they went buy, but he wasn't looking. Of course I had to watch carefully so I could critique the formation work. He was a little sucked on the roll . Maybe those long wings... man, I've heard that before!
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Last edited by scard : 07-28-2012 at 08:08 PM.
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  #116  
Old 07-28-2012, 08:11 PM
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drycreek drycreek is offline
 
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Quote:
Originally Posted by Walt View Post
NO, according to one of the RV reps at Osh the tail has been modified for the aerobatic loads, I also noticed the new trim tab has a riveted TE to match the TE of the elevator.
Does anyone know if the 14 trim tab will work on the 9?
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  #117  
Old 07-29-2012, 04:29 AM
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Quote:
Originally Posted by Archangel View Post

Here's the Flying Scotsman's List Reformatted
Code:
                       RV-7A      RV-9A      RV-14A
Light
Top Speed	       208	 197	    205
Cruise (75% @ 8000)   198	 189	    195
Cruise (55% @8000)    178        169        172
Stall Speed            51         44         56
Takeoff Distance (ft)  275        300        525
Landing Distance (ft)  350        300        545
Rate of Climb (ft/min) 2100       2000       1800
Ceiling (ft)           23,000     24,500     26,000
Range (75% @ 8000)                          938
Range (55% @ 8000)                          1103
Gross
Top Speed              207        196        203
Cruise (75% @ 8000)   197        188        193
Cruise (55% @8000)    177        168        169
Takeoff Distance (ft)  575        475        630
Landing Distance (ft)  350        450        715
Rate of Climb (ft/min) 1600       1400       1500
Ceiling (ft)           19500      19000      18,000+
Range (75% @ 8000)                          925
Range (55% @ 8000)                          1080
Specs
Span                   25'        28'        27
Length                 20' 4"     20' 5"     21 1
Height                 7' 10"     6'         8 2
Wing Area (sq.ft.)     121        124        126.1
Engine (hp)            180        160        210
Gross weight (lbs)     1800       1750       2050
Wing Loading (gross)   14.8       14.1       16.25
Power Loading (gross)  10         10.9       9.76
Empty Weight (lbs)     1077       1015       1240
Propeller                                    Hartzell c/s			
Fuel Capacity (US gal) 42         36         50
Baggage (lbs)          100        75         100
(useful load)          723        735        810
Given the take off and landing distances I am having problems reconciling the statement in the brochure: "Even at gross weight the RV-14 can operate from very short runways".
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  #118  
Old 07-29-2012, 04:57 AM
Richard Connell Richard Connell is offline
 
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Quote:
Originally Posted by Doug View Post
Given the take off and landing distances I am having problems reconciling the statement in the brochure: "Even at gross weight the RV-14 can operate from very short runways".
Exactly my thoughts Doug,

I guess the higher wing loading is creating the much longer landing distances.
I regularly fly in and out of a short (approx 900') field with obstructions at one end. I'm no test pilot, and regularly use around half of that. Nil wind in summer if its hot, I use more and it can be marginal (for me).
If the RV14 has double the landing distance of an RV7, then IMHO it isn't short field capable unless you are VERY proficient.
It does depend on you definition of "short" though

FWIW.

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  #119  
Old 07-29-2012, 11:04 AM
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skylor skylor is offline
 
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Default Stall Speed

Quote:
Originally Posted by Archangel View Post
Watching the Walk-Through Video here were the highlights I picked up on:

Here's the Flying Scotsman's List Reformatted
Code:
                       RV-7A      RV-9A      RV-14A
Light
Top Speed	       208	 197	    205
Cruise (75% @ 8000’)   198	 189	    195
Cruise (55% @8000’)    178        169        172
Stall Speed            51         44         56
Takeoff Distance (ft)  275        300        525
Landing Distance (ft)  350        300        545
Rate of Climb (ft/min) 2100       2000       1800
Ceiling (ft)           23,000     24,500     26,000
Range (75% @ 8000’)                          938
Range (55% @ 8000’)                          1103
Gross
Top Speed              207        196        203
Cruise (75% @ 8000’)   197        188        193
Cruise (55% @8000’)    177        168        169
Stall                  58         50         56
Takeoff Distance (ft)  575        475        630
Landing Distance (ft)  350        450        715
Rate of Climb (ft/min) 1600       1400       1500
Ceiling (ft)           19500      19000      18,000+
Range (75% @ 8000’)                          925
Range (55% @ 8000’)                          1080
Specs
Span                   25'        28'        27’
Length                 20' 4"     20' 5"     21’ 1”
Height                 7' 10"     6'         8’ 2”
Wing Area (sq.ft.)     121        124        126.1
Engine (hp)            180        160        210
Gross weight (lbs)     1800       1750       2050
Wing Loading (gross)   14.8       14.1       16.25
Power Loading (gross)  10         10.9       9.76
Empty Weight (lbs)     1077       1015       1240
Propeller                                    Hartzell c/s			
Fuel Capacity (US gal) 42         36         50
Baggage (lbs)          100        75         100
(useful load)          723        735        810
To be completely truthfully, the Gross Weight Stall Speeds should be included in this list, which I have added. The 14A looks a bit better at gross...

Skylor

Last edited by skylor : 07-29-2012 at 11:07 AM.
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  #120  
Old 07-29-2012, 11:13 AM
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Mel Mel is offline
 
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So, the stall speed stays the same regardless of weight?

Interesting. At light weight the stall speed of the -14 is 5 mph higher than the -7, but at gross weight it is 2 mph lower.

How they do that?
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Last edited by Mel : 07-29-2012 at 11:21 AM.
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