Monday, March 29, 2010

A New Appreciation for Aspect Ratio

Say, something looks a little funny here...
(And it's NOT me !! :)

While shuffling around the flight line one day, I took a break from looking at my shoes and belly button, and happened to look up. Not quite at the stars, as it was daytime. There is a subtle danger with when and where one looks- I had a friend who would fall asleep in a car with his eyes open. Fortunately, this was only when he was riding, rather than driving. I've heard it said that such things are a symptom of insanity. (Which might explain his choice of friends... or render a verdict on my conversational skills).

Surfing the web a bit, it would appear that- no, it is not a sign of insanity, but a neurological abnormality. Reckon some misconception like that is how the Salem witch trials started. (It was kinda spooky though). Fortunately, driving into something wasn't a danger for my friend- but staring into the sun was. Anyway- I was more-or-less awake (I doubt if my boss would appreciate a helpful website I found while researching my friend's problem: "How to Rest With Your Eye's Open"), and not staring into the sun, but nonetheless, what I saw rather started me into a heightened sense of awareness; I happened to look up at the wing of a Dash-8.

And, by golly, it was a rather odd sight. Such a long airplane, and a reasonably long wingspan- but a markedly short-cord wing.

I had flown on a Dash-8 over the holidays, and was modestly impressed. Or if you prefer, modestly impressed it wasn't as bad as I expected: equivalent to a typical RJ in passenger "comfort", but at least it had a certain quaintness about it. It was fairly fast (perhaps a 25% longer trip time on the 400 nm one-way journey), and yes, noisier- even though it was the "Q" model with active noise cancellation.

I'm no aerodynamicist, but for years (like, decades), I've heard "how much more efficient a turboprop is" than a jet. I don't know why that is supposed to be true- but after contemplating the seemingly high aspect ratio of the Dash-8 wing, I wondered if that was a key element.

Aspect Ratio is defined as the wingspan-squared divided by wing area. This gets a little tricky when one considers what is "wing area"- the parts that jut out from the fuselage, or should the fuselage area that "connects the wings" be included in area. I believe this is called "gross area" (as opposed to net area excluding the fuselage area between the wings), and it is what I tried to use for all the comparisons. (Some of the data was vague, but I did my best to maintain consistency- please point out any corrections to individual aircraft if you see them).

In general, a wide wingspan, and small area (short cord) yield a high aspect ratio, and higher efficiency, with less induced drag. There are some complications though(fuel area, wing bending loads, flight control packaging).

I had been thinking of a typical jet as having an aspect ration of around 8; which turns out to be not such a bad estimation. I was considerably surprised in checking a multitude of aspect ratios, with the high placement of turboprops. I did a relatively thorough comparison of a wide variety, and 250 aircraft (see list at the end), and I was reasonably astonished at the Aspect Ratio placement of regional airliner turboprops: below are the two dozen highest aspect ratio airplanes. The turboprop commuter aircraft fell neatly between a reasonably capable older sailplane (Schweizer 1-26), and the Lockheed U2: quite surprising, to me anyway.

As VLJ fans (of sorts), I thought it interesting to note the Eclipse 500 aspect ratio is approx. 9.69, and the Cessna Mustang a 8.89.

Interestingly, the Boeing 787-8 has an aspect ratio of approx 11.12, versus 8-to-9 for other Boeing contemporary models. Airbus models were generally 9-to-10 (except for the A380, 7.52; perhaps structural constraints- especially wing bending loads for such a heavy airplane, kept the wingspan shorter.

ManufacturerModelName/CommentsA.R.(gross)
RutanModel 76Voyager (non-stop prop)33.85
Scaled CompositesModel 311Global Flyer (non-stop SEJ)32.49
NorthropRQ-4AGlobal Hawk25.01
SchleicherASW28Sail Plane21.42
General AtomicsMQ-1Predator19.23
GrobG-102Astir (sailplane)18.27
SchweizerS1-26Sailplane15.17
LockheedRQ-3Dark Star14.83
DeHavilandDHC-8-300Twin Turboprop13.39
SonexXenoshomebuilt sailplane13.22
DeHavilandDHC-8-400Twin Turboprop12.79
Hawker SiddeleyHawker Siddeley HS 748Turboprop12.67
ShortsC-23ASherpa12.32
PiaggioPA-180Avanti (main wing)12.29
ATRATR-72Twin Turboprop12.01
SchweizerS2-33Sailplane11.85
BoeingB-29Superfortress11.51
BoeingB787-8Airliner11.12
ATRATR-42Twin Turboprop11.09
BoeingB-36Peacemaker11.09
DiamondDA42TTwin Engine11.06
Saab2000Twin Turboprop11.02
Dornier328Twin Turboprop11.01
Beech1900DPuddle Hopper10.85
LockheedU-2SSpy Plane10.61

Here's the Great-Grand Daddy of all Aspect Ratios lists.

(There were some notable difficulties- swing wing geometries didn't list different wing areas for swept versus non-swept, although some reading suggests it's about a 10 percent reduction). Also, canard configurations are a bit more difficult to compare (should the canard be included in wing area? I did not). Also bi-planes (Wright Flyer) counted both wing areas, although I've read somewhere that a rule of thumb is only a 10% gain in effective wing area for a biplane.

It's kind of fun to look at the data sorted in other ways too (might have to download them and then open them- quirky Google docs issues- even quirkier operator...me!):

By Manufacturer/Model

By Wing Span

By Wing Area

By MTOW

By Wing Loading (at MTOW)

Oh, what the heck- Here's the whole list! (Just in case there are difficulties opening the Google doc files. Plus, I was curious to see how big of a spreadsheet I could upload. "Just because you can, doesn't mean you should ..." :)



ManufacturerModelName/CommentsWingspan (ft)Wing Area (sq.ft)MTOW (lbs)A.R.(gross)Wing.Load
WainfainFMX-4Facetmobile (Homebuilt)152147401.053.46
Birdman, IncWing.suitDarwin Special5161801.5611.25
LockheedSR-71Spy Plane55.618001720001.7295.56
General DynamicsF-16XL(Cranked Arrow Wing)34.25646480001.8274.31
Aerospatiale/BACConcordeSST8438564120001.83106.85
TupolevTu-144SST94.547153970001.8984.19
Dassault2000Mirage29441.3375001.9184.98
General DynamicsF-111.sweptAardvark325251000001.95190.47
FaireyDelta 2Supersonic Research26.8360138841.9938.56
ConvairB-58Hustler56.815421768902.09114.71
NorthropYF-23Black Widow II43.6900620002.1168.89
RockwellSpace.ShuttleSpace Brick78.0628402300002.1580.98
BoeingX-32Ugliest Airplane Award36590380002.1964.41
ConvairF-102ADelta Dagger38.1661.5315002.2147.61
ConvairF-106Delta Dart38.25661.5418302.2163.23
VoughtXF5UFlying Pancake32.5475187722.2239.52
LockheedF-22Raptor44.5840835002.3699.04
LockheedF-104GStarfighter21.75196.1290272.41148.02
LockheedF-117Nighthawk43.3780525002.4167.31
North AmericanX-15Rocket plane22.3200340002.49170.01
GrummanF-14D.sweptTomcat38565743502.56131.59
LockheedF-35A (USAF)Lightning II35460700002.66152.17
DouglasA-4Skyhawk26.5259245002.7194.59
AvroVulcanBritish Flying Wing99.435541700002.7847.83
McDonnellF-4EPhantom II38.4530617952.78116.59
McDonnellF-15EStrike Eagle42.8608810003.01133.22
DouglasX-3Stiletto22.7166.5238403.09143.18
RepublicF-105Thunderchief34.9385525463.16136.48
Wright BrosFlyer(Bi-plane, calc. w/o canard)40.35107453.181.46
RockwellB-1BLancer (wings swept)7919504770003.21244.61
VoughtF-8ECrusader35.7375340003.3990.67
MitsubishiF-2(F-16 Agile Falcon)36.5375330003.5588
General DynamicsF-16CFalcon32.7300423003.56141.01
McDonnellAV-8BHarrier II30.25243.4310003.76127.36
North AmericanF-100DSuper Saber38.8400348323.7687.08
McDonnell/Gen DynA-12Avenger II70.31308800003.7861.16
NorthropF-5ETiger II26.7186246643.83132.61
GrummanX-29Forward Swept Wing27.2188.8178003.9294.27
McDonnellF-18ESuper Hornet44.7500660003.99132.01
McDonnellF-18CHornet40400515504.01128.87
North AmericanA-5Vigilante53700629534.0189.93
VoughtA-7ECorsair II38.8375420004.01112.01
NorthropT-38Talon26.25170125004.0573.53
McDonnellF-101BVoodoo39.7368524004.28142.39
North AmericanF-86FSaber37313.4181524.3757.92
SonexSonexhombuilt229811004.9411.22
Handley PageB.1Victor11024061850005.0376.89
GrummanA-6Intruder53529606265.31114.61
GrummanEA-6BProwler53529615005.31116.26
LockheedJetStar IIBiz Jet54.9542445005.5682.11
PiperPA-28-140Cherokee-fill in the blank3016021505.6213.44
NorthropB-2Spirit17251403365005.7665.47
North AmericanT-39DSaberliner44.5342.1177605.7951.91
PiperPA-22Tri-Pacer29.3147.520005.8213.56
BellX-1Rocket plane28130122506.0394.23
BeechD35Bonanza32.817827256.0415.31
General DynamicsF-111.landingAardvark63657.41000006.04152.11
GrummanAA-1Yankee24.59815006.1215.31
BeechG-36Bonanza33.518136506.2120.16
CessnaT-37Tweet33.8183.965696.2235.72
Hawker SiddeleyHS 125-700Biz Jet47353255006.2672.24
ERCOErcoupeWhatz-Zat30142.614006.319.82
BAE SystemsMRA4(Evolved DeHaviland Comet)12725382323156.3691.53
GulfstreamG.450Biz Jet77.8950739006.3777.79
WittmanW10Tailwind (Homebuilt)249014256.415.83
Convair990Coronado12022502530006.41112.44
BedeBD-5AMicrojet1430.57006.4322.95
Fairchild-RepublicA-10Thunderbolt II (Warthog)57.5506500006.5398.81
Rockwell100Darter3518122506.7712.43
CessnaICitation-fill in the blank43.5278.5118506.7942.55
DouglasDC-10-15Airliner155.335504550006.79128.17
Cessna 310Twin prop3517946006.8425.69
DouglasDC-10-40Airliner165.339585550006.91140.22
BeechB77Skipper30129.816756.9312.9
Cessna150Commuter33.316016006.9310.01
CessnaBravoCitation-fill in the blank47.3322.9148006.9345.83
BellV-22Tilt Rotor, fixed-wing only45.8301.4605006.96200.73
BoeingB747-300Airliner195.755008330006.96151.45
LockheedL-1011-200TriStar155.334564660006.98134.84
PiperJ-3Cub35.3178.512206.986.83
BoeingKC-135RAirliner130.924333225007.04132.55
BoeingB707-320BAirliner145.7530103360007.06111.63
Hawker800Hawker 80051.4373.9280007.0774.89
BoeingB727-200Airliner10816472095007.08127.21
BeechB55Baron37.8199.251007.1725.61
Cessna337DSkymaster3820144007.1821.89
Hawker4000Hawker 400061.8530.8395007.1974.42
Lear31Learjet43.67264.8155007.2158.53
PiperPA-31-310Navajo40.722965007.2328.38
LearModel 60Lear 6043.8264.8235007.2488.75
BeechB60Duke39.3212.967757.2531.82
Ford5-ATTrimotor ("Tin Goose")77.8835135007.2516.17
GrummanF-14D.landingTomcat64565743507.25131.59
PiperPA-24-260Commanche3617832007.2817.98
DouglasDC-8-32Airliner142.427713100007.32111.87
TerrafugiaTerrafugiaFlying Car27.5103.114747.3314.29
LearModel 45Lear 4547.8311215007.3569.13
BeechB23Musketeer32.814624007.3716.44
NorthropYB-35Flying Wing (props)17240002090007.3952.25
NorthropYB-49Flying Wing (jet)17240001939387.3948.48
Cessna182Skylane3617431007.4517.82
Cessna172Skyhawk36.117424507.4914.08
VickersVC-10Airliner146.228513348787.49117.46
Cessna162Skycatcher3012013207.5111.01
AirbusA380Airliner261.6910013000007.52142.86
DouglasDC-8-63CFAirliner148.429273550007.52121.28
MooneyM20TNAcclaim36.4175.733747.5419.21
McDonnell-DouglasC-17Globemaster III169.838005850007.59153.95
PiperPA-39Twin Commanche36.817837257.6120.93
LockheedL-1011-500TriStar164.335415100007.62144.03
LockheedP-3Navy Patrol99.713001420007.65109.23
BombardierCRJ-700Airliner76.3760750007.6698.68
BoeingB747-400Airliner211.458259100007.67156.22
CessnaXBiz Jet63.6527364007.6769.07
GulfstreamG.550Biz Jet93.61137910007.7180.04
GulfstreamG.650Biz Jet99.61283996007.7377.73
BoeingB777-200ERAirliner188.846054700007.74102.06
Cessna210Centurion36.817540007.7422.86
PiperPA-42-720Cheyenne IIIA47.7293112007.7638.22
BombardierCL-300Challenger63.8522388507.7974.42
CessnaSovereignCitation-fill in the blank63.1510303007.8159.41
Beech400ABeechjet43.5241.4161007.8466.69
Hawker400(Beechjet/Diamondjet)43.5241.4161007.8466.69
CessnaCJ-4Citation50.9329.9169507.8551.38
Cessna421CGolden Eagle41.121574507.8634.65
EmbraerERJ-140LRRegional Airliner65.8550.9465177.8684.44
BoeingB737-200Airliner931097.51155007.88105.24
McDonnell-DouglasMD-11ERAirliner169.536486305007.88172.83
Cessna340ATwin prop38.118459907.8932.55
BoeingB737-400Airliner94.711351500007.91132.16
CessnaSIICitation52.2342.5151007.9644.09
BeechB-76Dutchess3818139007.9821.55
BoeingB757Airliner124.819512725007.98139.67
BoeingB767-300Airliner156.130503150007.98103.28
BoeingB767-300ERAirliner156.130504120007.98135.08
CessnaV & UltraCitation-fill in the blank52.3342.6163007.9847.58
LockeedC-5BGalaxy222.762008400007.99135.48
BeechPremier 1ABiz Jet44.5247125008.0250.61
Cessna 303Clipper/Crusader39189.251508.0427.22
AirbusA400MCargo139.123843108528.12130.39
Lear23Learjet43.3231125008.1254.11
BombardierCRJ-1000Airliner85.9883918008.35103.96
TupolevTu-95Bear167.733304145008.45124.47
BoeingB747-8iAirliner224.659639750008.46163.51
CessnaXLS+Citation-fill in the blank56.3371202008.5454.45
AntonovAn-124Condor240.467608930008.55132.11
BoeingB-52Stratofortress18540004880008.56122.01
DouglasDC-9-10Airliner89.4934907008.5697.11
BeechC90GTKingAir50.3294101008.6134.35
MitsubishiMU-2Twin Turboprop39.2178115758.6365.03
AntonovAn-225Mriya290.2974413230008.64135.78
BombardierGlobal.ExpressXRSBiz Jet941022995008.6597.36
Cessna402CBusinessliner44.2225.868508.6530.34
BoeingB777-300Airliner199.946055450008.68118.35
Cessna425Corsair/Conquest I44.222582008.6836.44
DouglasDC-9-50Airliner93.410011210008.71120.88
McDonnell-DouglasMD-95(also Boeing 717)93.410011210008.71120.88
BombardierCRJ-900Airliner81.5760845008.74111.18
LockheedC-141BStarlifter168.332283421008.78105.98
Cessna404Titan46.324284008.8634.71
CessnaMustangCitation43.221086458.8941.17
SlingsbyT-3AFirefly34.813625508.9118.75
EmbraerERJ-195Regional Airliner94.39961152808.93115.74
Socata850Single Engine Turboprop41.6193.773948.9338.17
HughesH-4Spruce.Goose320114304000008.9634.99
CessnaEncoreCitation-fill in the blank54.1322166309.0951.65
BoeingB767-400ERAirliner170.331804500009.12141.51
DouglasDC-3DeeCee-Three95987183009.1418.54
GulfstreamG-200(Galaxy)58.1369354509.1596.07
AirbusA340-500Airliner208.247308400009.16177.59
CessnaCJ1+Citation-fill in the blank46.9240107009.1644.58
CessnaIIICitation-fill in the blank53.5312220009.1770.51
ExtraEA-400Composite, piston37.7153.644099.2528.71
PiperPA-38-112Tomahawk34124.716709.2713.39
EmbraerERJ-175Regional Airliner85.3783855169.29109.22
BombardierCRJ-200Regional Airliner69.6520.4530009.31101.85
CessnaCJ2Citation-fill in the blank49.8263.6123009.4146.66
BoeingB-47Stratojet11614282300009.42161.06
LearModel 85Lear 8561.5401335009.4383.54
DouglasDC-6DeeCee-Six117.514631070009.4473.14
RockwellCommander-500Piston Twin49.125567509.4526.47
BoeingB737-800Airliner112.613401742009.46130.01
DouglasDC-4DeeCee-Four117.51460730009.4650.01
General AtomicsMQ-9Reaper66460105009.4722.83
AirbusA320Airliner111.91320940009.4971.21
AirbusA350Airliner21347705910009.51123.89
Cessna441Conquest II49.3253101659.6140.18
McDonnell-DouglasMD-83Airliner107.812091600009.61132.34
RockwellB-1B Lancer (landing config)13719504770009.62244.61
LockheedL-1049GSuper Constellation126.216541375009.6383.13
McDonnell-DouglasMD-90-30ERAirliner107.912091680009.63138.96
CessnaCJ3Citation-fill in the blank53.3294138709.6647.18
EclipseEA500Oh Be Nice37.4144.459509.6941.21
Cessna 206BCaravan52.1279.487509.7131.31
Dassault7XFalcon (three engine)86761700009.7291.98
DouglasDC-7DeeCee-Seven127.516371430009.9387.35
BristolType 167Brabazon (post WW2, 8xradial)23053172900009.9554.54
AirbusA330Airliner197.9389251000010.06131.04
LockheedC-130HCargo132.6174515500010.0888.82
PiperPA-46-500TPMeridian43183509210.1127.83
CirrusSR-22who needs a name38.3144.9340010.1223.46
DiamondDA-20Katana35.7125176410.1914.11
PilatusPC-12Single Engine Turboprop53.3277.81045010.2337.62
BoeingB737-800(with winglets)117.4134417420010.26129.61
Shorts360Twin Turboprop74.85442600010.2847.79
SwearingenMetroliner-23Twin Turboprop573101600010.4851.61
BeechB350Kingair35057.113101500010.5248.39
Beech2000AStarship (main wing)54.52811490010.5753.02
DiamondDZ40XLSingle Engine39.2145.3264510.5818.2
LockheedU-2SSpy Plane10310004000010.6140.01
Beech1900DPuddle Hopper583101712010.8555.23
Dornier328Twin Turboprop68.94313084011.0171.55
Saab2000Twin Turboprop81.36005026511.0283.78
DiamondDA42TTwin Engine44175374811.0621.42
ATRATR-42Twin Turboprop80.65864100011.0969.97
BoeingB-36Peacemaker230477241000011.0985.92
BoeingB787-8Airliner197.3350150250011.12143.53
BoeingB-29Superfortress141.3173613350011.5176.91
SchweizerS2-33Sailplane51219.5104011.854.74
ATRATR-72Twin Turboprop88.8656.65026512.0176.55
PiaggioPA-180Avanti (main wing)46172.21155012.2967.07
ShortsC-23ASherpa74.74532290012.3250.55
Hawker SiddeleyHawker Siddeley HS 748Turboprop102.58294650012.6756.09
DeHavilandDHC-8-400Twin Turboprop93.26796450012.7994.99
SonexXenoshomebuilt sailplane45.7158127513.228.07
DeHavilandDHC-8-300Twin Turboprop90604.74300013.3971.11
LockheedRQ-3Dark Star69321850014.8326.48
SchweizerS1-26Sailplane46.2140.771015.175.05
GrobG-102Astir (sailplane)49.313399018.277.44
General AtomicsMQ-1Predator48.7123.3225019.2318.25
SchleicherASW28Sail Plane49.2113115721.4210.24
NorthropRQ-4AGlobal Hawk116.25402290025.0142.41
Scaled CompositesModel 311Global Flyer (non-stop SEJ)1144002210032.4955.25
RutanModel 76Voyager (non-stop prop)110.73629694.533.8526.78