More lift, but more drag. Why do we still use biplanes?

Ok, so “we” is really a couple of stunt pilots, some vintage aircraft enthusiasts, and a handful of Russians, but even so, they’re still around.

Don’t get me wrong, I love biplanes as much as the next guy, but I’ve read about the inherent inefficiencies they have- the obvious one, more lift means more induced drag, and how the wings disrupt each other’s airflow. This means a monoplane of similar build (but with different or more wing, though) should do better at EPA mileage tests than a draggy biplane. Of course, this is still information gathered mostly from the intrawebs, but it seems legit.

So, why do we, who live in the modern world of Sukhois and Extras, still have Pitts raising hell in heaven? Instead of dropping in a turbine in your An-2, why not get yourself a Twin Otter? Are these double-decked pilots hiding something from their mono-winged bretheren, or are they just clinging to romantic views of barnstorming?

Just like cars, sometimes people want something fun rather than just fast and efficient. Also, many negatives in aviation can also be turned into a positive. In this case, biplanes have high drag at higher speeds but that can also fly slowly as well. That is good for crop dusting, some aerobatics, and sightseeing. They have lots of drag because they have all those extra struts and things but those also make them strong and able to take lots of abuse on unimproved fields and extreme G loads. Most of this stuff can be done as well with a specialized single wing plane but some people like a slow flying, open cockpit plane that can take a lot of abuse.

Here is a thread that’s similar enough that you might find it interesting.

The Quickie Q200 is often called a canard-configuration, but it’s really a biplane with radical step-back of the top wing. It’ll do about 200 mph and get great ‘gas mileage’. Too bad they don’t make them anymore.

Shagnasty- I was wondering about the cropdusting applications but had forgotten to ask- makes sense now, I hadn’t thought of slow flight performance… guess slow and steady wins the aerobatics competition.

Speaker of the Dead- Thanks, now I’ve got some reading up to do…

Johnny L.A.- You reminded me of the Quikkit Glass Goose, a kit amphibious biplane that’s fairly recent (uh, you know, compared to Tiger Moths and Wacos and the like)

Thanks all!

True. But all aircraft (in unaccelerated flight) produce lift equal to their weight - a 1000-lb monoplane generates the same lift as a 1000-lb biplane.

By contrast, the parasitic drag of a biplane is likely to be greater than that of a monoplane, due to greater wetted area and such things as struts and bracing wires.

Biplanes don’t necessarily have good slow flight charcteristics. The Pitts, for example, has a relatively high stall speed, and no flaps or any other lift enhancing devices. The AN2 though, is pretty impressive into short strips!

I think a lot of it is due to aesthetics. High performance aerobatic monoplanes like the Extra, Sukhois, and so on, are better machines than a stock Pitts, but they don’t have much character IMO.

Note that biplanes have the same wing area for a smaller span. You’re keeping the mass closer to the roll axis, so the plane will roll quicker, other things being equal.

Because they’re fun to fly.

That, too.

Didn’t the WW2 British Lysander and the German Fiesler Storch have very low stall speeds and were capable of landing on very strips.

…small strips that is :smack:

Yes, and they were both high-wing monoplanes. What about it?

Though the question was answered fairly well, just something to consider.

You’re asking why someone would still fly an old plane design. But the real question is why old planes were designed that way and modern ones not. When the Wright brothers built their plane, they did a lot of testing of wings, propellers, etc. running them in a makeshift wind-tunnel. And in the end they decided on a biplane.

And the reason for that is because, as the above posts show, a biplane allows for a sturdier plane and for very slow flying (which was all they could hope for based on the engines of the day.) So, for anything in the modern day world which requires sturdy, slow flyers, a biplane will still be the design of choice just because that’s the best shape for the job.

I think this is a bit misleading. The Wrights decided on a biplane design very early in their work, before they’d built a wind tunnel or done anything at all with propellors (in 1900 - 1902, they were flying gliders).

One reason for a biplane is as you state: it’s a way of building a sturdy aircraft of acceptably low weight. Another important one was that it was amenable to the wing-warping scheme that they’d discovered could produce the controlled variations in angle of attack which they believed (correctly as it turned out) would give them roll control.

In airshow (as distinguished from competitions) aerobatics, high drag and slow speed can be advantagious from a showmanship standpoint.

Slower flight and the ability to dive without building a ton of excess speed can lead to a close-in routine. This is crowd pleasing because the audience gets a great visual view, and lots of engine noise.

Much of the high drag is wing vorticies which dispirse the smoke into a wide, impressive trail.

Biplanes are pretty much required for the wingwalking routine that is a traditional staple of airshows.