Why Cessnas not Biplanes

[The Basket]

I saw an airplane and I was thinking why isn't that a biplane?

So why do all modern general aviation have single wings?

The top speed of these aircraft are negligible so drag isn't an issue.

But better STOL and stalling speed would be a great boon.

 

[pbehn]

I saw an airplane and I was thinking why isn't that a biplane?

So why do all modern general aviation have single wings?

The top speed of these aircraft are negligible so drag isn't an issue.

But better STOL and stalling speed would be a great boon.

I think cost and drag is an issue. Even a cruising speed of 122knots (Cessna 172) is fast in automotive terms, get up to 120MPH and stick an arm out of your car window, oh and then check out your cars consumption.

 

[jetcal1]

I saw an airplane and I was thinking why isn't that a biplane?

So why do all modern general aviation have single wings?

The top speed of these aircraft are negligible so drag isn't an issue.

But better STOL and stalling speed would be a great boon.

If you look at the most pure "modern" aircraft from the late 40's - early '50's you'll find that the some aircraft like the original Bonanza cruised quite efficiently at around 170 MPH using about 150 HP from their 185 HP engines. Many European aircraft did even better on less HP, but traded range and useful load. (Stelio Frati immediately comes to mind.)

There is no biplane that I am aware of that had a comparable performance/HP/cost ratio.

 

[swampyankee]

I saw an airplane and I was thinking why isn't that a biplane?

So why do all modern general aviation have single wings?

The top speed of these aircraft are negligible so drag isn't an issue.

But better STOL and stalling speed would be a great boon.

Their top speeds are hardly "negligible"; a biplane with the same payload-range performance as a Cessna 172 would be considerably heavier and require a significantly larger engine. I don't know whether they'd have better STOL characteristics -- most STOL aircraft are monoplanes, at least partly because flaps are less effective on biplanes -- and the stalling speed of a 172 is already pretty low.

The only technical advantage of a biplane* is that the interwing struts can be used to permit lower wing weight.


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* Unless you're going to go into seriously high-tech aerodynamic optimization, such as joined-wing configurations, which tend to have the problem of places to put the fuel.

 

[gumbyk]

I saw an airplane and I was thinking why isn't that a biplane?

So why do all modern general aviation have single wings?

The top speed of these aircraft are negligible so drag isn't an issue.

But better STOL and stalling speed would be a great boon.

Drag is an issue even at low speeds. If you have an engine failure in a bi-plane, you'd better be pretty quick getting the nose down to maintain speed, and your glide profile is pretty steep.

Cost of manufacture also enters the equation; building another set of wings would significantly increase the manufacture costs. Rigging the aircraft wings and control surfaces is more complicated as well.

 

[michael rauls]

Drag is an issue even at low speeds. If you have an engine failure in a bi-plane, you'd better be pretty quick getting the nose down to maintain speed, and your glide profile is pretty steep.

Cost of manufacture also enters the equation; building another set of wings would significantly increase the manufacture costs. Rigging the aircraft wings and control surfaces is more complicated as well.

I would have thought with all that extra wing area that biplanes would have more lift and a better glide profile. Curious why this would not be the case.
Because the increased drag outweighs the increased lift maybe?

 

[GrauGeist]

There is no biplane that I am aware of that had a comparable performance/HP/cost ratio.

I'd say that the Beech Staggerwing, even though it is 1930's vintage, would be the most modern biplane with comparable (or even better) performance.

 

[gumbyk]

I would have thought with all that extra wing area that biplanes would have more lift and a better glide profile. Curious why this would not be the case.
Because the increased drag outweighs the increased lift maybe?

Yes, the increased lift is more than offset by the drag increase, particularly at high angles of attack.

At high angles, the induced drag (the drag associated with the production of lift, like wingtip vortices) is increased, and with twice the number of wingtips, you're going to get more induced drag.
You've also got bracing wires, although in a modern version you wouldn't need them.

It's a very simplified way of thinking about it...

 

[gumbyk]

I'd say that the Beech Staggerwing, even though it is 1930's vintage, would be the most modern biplane with comparable (or even better) performance.

I guess that if you were to design a new bi-plane, it'd look something like this:

120 kts on 23l/hr and 125 hp

 

[Shortround6]

Specs for a Beech D-17-A Biplane with a Wright R-760-E2 engine (350hp for take off and 320hp at 1400ft max continuous or normal) are.

Useful load 1735lb, payload with 98 gal fuel, 928lb (4 passengers and 248lbs for baggage and "extras") Gross weight 4200lbs, max speed 180mph at sea level, cruise using 75% power at 9300ft was 170mph, Cruising range at that speed and altitude was 850 miles burning 17.5 gallons an hour. retractable landing gear

Post war Cessna 195 using a 300hp Jacobs engine.
Useful load 1300lb, payload with 80 gal fuel, 583lb (3 passengers and 100lbs for baggage and "extras") Gross weight 3350lbs, max speed 180mph at sea level, cruise using 70% power at 6500ft was 159mph, Cruising range at that speed and altitude was 700 miles burning 16 gallons an hour. fixed landing gear.

1947-48 Beechcraft Bonanza with a 185hp take off E-185 Continental (165hp max continuous)
Useful load 992lb, payload with 39 gal fuel, 570lb (3 passengers and 60lbs for baggage and "extras") Gross weight 2550lbs, max speed 184mph at sea level, cruise using 60% power at 10,000ft was 160mph, Cruising range at that speed and altitude was 650 miles burning 8.6 gallons an hour. retractable landing gear.

The Beech 17 was available with both smaller and larger engines.

 

[FLYBOYJ]

So why do all modern general aviation have single wings?

$$$$$$

 

[Graeme]

I'd say that the Beech Staggerwing, even though it is 1930's vintage, would be the most modern biplane with comparable (or even better) performance.

There was an attempt in the late 90's to produce a modern version of the Staggerwing in kit-form - but looking at Wikipedia, not many were built...

 

[swampyankee]

I would have thought with all that extra wing area that biplanes would have more lift and a better glide profile. Curious why this would not be the case.
Because the increased drag outweighs the increased lift maybe?

That would be one reason. The other is that biplanes tend to have lower maximum lift coefficients, so a biplane needs about ten percent more wing area to get the same stall speed for a given weight.

 

[swampyankee]

For a modern biplane,

I present Sorceress:
Attribution: Jarek Tuszyński / CC-BY-SA-3.0 & GDFL

 

[Elmas]

There is also a difference between piloting a monoplane and a biplane, so I was told by Gen. Aldo Costa, who took his Flying Brevet on the Spad XIII (sic) that I had the possibility to interview when He was in his early '80 (in the early '90s). In this photo Gen, Costa, then a Captain is at the far right

While a modern monoplane, say a monoplane with an evolving wing profile and a convenient wash-out, once trimmed, can fly almost by hitself, not the same thing can be said for a biplane, that generally needs a constant adjustment on the stick. First monoplanes vere rather unstable not only because they had no evolving profiles and no wash-out (in Italy G.50 and Macchi MC 200 Serie I, to say two), but also because Pilots, accustomed to biplanes, were acting too much on the stick, adding worse to the worst.

So, considering that it is absolutely essential that a GA light airplane has to be safe and simple to fly by non professional pilots and adding all considerations about drag etc seen in the above post ( let's not forget that drag is proportional to the square of the speed), no wonder that biplanes are not fashionable anymore in the GA.
Same reason, I suspect (ease and safety of fly) that led to install in a light GA airplane a yoke instead of a stick.
Certainly, there are exceptions, like this biplane, designed, built and flown by some Friends of mine...

 

[gumbyk]

I don't find the Tiger moth to be any 'harder' to fly than a Piper Cub, but it is different. With a lower wing loading, it is more easily disturbed from level flight, and you are correct, it does need constant attention, but I think that is more to do with design philosophy than the bi-plane; e.g. the trim only has detents where it locks, so if you need a trim position between two, you're out of luck.

 

[MIflyer]

I heard of a guy who converted a Piper J-3 into a biplane.

He lost in every performance category, climb, top speed, etc.

 

[XBe02Drvr]

Clearly, no sailplane pilots have checked in to this thread yet, and all shots have been on the paper, but nobody's hit the X ring yet.
The holy grail of airframe performance is L/D, the ratio of lift to drag, most easily achieved with a monoplane, and in the most extreme form by a canard or a sesquiplane on the order of a Rutan Long Eze or a Quickie. Given that a sleek efficient monoplane like an early Bonanza is relatively easy and economical to design and produce, and is the more efficient layout it's not surprising that paradigm has become dominant. Try matching a Luscombe's or an Ercoupe's performance on 65 HP with a biplane, or a Cessna 170's on 145 HP.
The increased expense and reduced performance/HP of "modern" GA aircraft vis a vis their ancestors comes from hanging more gewgaws, "luxury", and STOL airframe mods on them, and the additional HP to compensate. Compare the E185 powered Bonanza mentioned upthread with its most recent descendant in the Vee tail line. More electronics, more weight, more seats, more luxurious appointments, more HP, and of course, MUCH MORE $$$$$$$! (But less performance/HP) The sports coupe has become a limousine.
Cheers,
Wes

 

[MIflyer]

Well, of course part of the reason is advancement in materials and construction methods. There have not been many aluminum stressed skin cantilever wing biplanes built. And before those construction methods were developed there were not many monoplanes built using biplane wood and tube construction methods.

It is interesting that the Ercoupe and Luscombe were built with all aluminum structures but still had fabric covered wings. The fabric was not needed for structure but just to keep the wind from going somewhere it should not. And those were good designs, too, even by today's standards. My Ercoupe was 30 lb lighter and had less drag when then wings were fabric covered; I wish they still were.

 

[jetcal1]

Well, of course part of the reason is advancement in materials and construction methods. There have not been many aluminum stressed skin cantilever wing biplanes built. And before those construction methods were developed there were not many monoplanes built using biplane wood and tube construction methods.

It is interesting that the Ercoupe and Luscombe were built with all aluminum structures but still had fabric covered wings. The fabric was not needed for structure but just to keep the wind from going somewhere it should not. And those were good designs, too, even by today's standards. My Ercoupe was 30 lb lighter and had less drag when then wings were fabric covered; I wish they still were.
View attachment 560864

But....you don't have to about recovering the wings.