Could the Wright Flyer take off without wind?

[MarceloJenisch]

TL;DR Summary

To discuss the capability of the 1903 Wright Flyer to takeoff without wind

Hello,

I'm wondering if the 1903 Wright Flyer would be able to take off without wind supposing it had a longer takeoff track. Some people here in Brazil claim that there's no proof the Wright Flyer would be able to lift off under its own power. Generally, this revolves around the catapult question, but some people also point to the strong wind the 1903 Flyer used for takeoff. And yes, I'm aware that the 1903 model didn't use a catapult.

The Flyer was able to sustain itself in the air. Since indicated airspeed is not affected by the wind (unless in a windshear), it was pretty much ok as far as the flight itself was concerned. My doubt is really about if it would have the capability to achieve flying speed in a calm wind scenario. I think the major question is if it would be able to overcome the friction of the track. I'm aware that friction does decrease with airspeed. Therefore, I guess if it was capable of reaching 15 mph, it would more easily attain 20, 25, until it would lift off. I'm missing something with my reasoning? What are your views about this?

 

[russ_watters]

I think the major question is if it would be able to overcome the friction of the track. I'm aware that friction does decrease with airspeed. Therefore, I guess if it was capable of reaching 15 mph, it would more easily attain 20, 25, until it would lift off. I'm missing something with my reasoning? What are your views about this?

Track friction doesn't decrease with airspeed, it's constant. But propeller thrust does decrease with speed. So I believe it would not have taken off under it's own power alone.

 

[MarceloJenisch]

Track friction doesn't decrease with airspeed, it's constant. But propeller thrust does decrease with speed. So I believe it would not have taken off under it's own power alone.

Track friction is really constant? According to this source:

https://books.google.com.br/books?id=6-_iGbJHM-8C&pg=PA302&dq=ground+friction+and+airspeed&hl=pt-BR&sa=X&ved=2ahUKEwj-rILB8s_0AhWfppUCHRqeDAkQ6AF6BAgEEAM#v=onepage&q=ground friction and airspeed&f=false

An increase in the lift coefficient will result in a decrease of rolling friction. But of course, that book is about airplanes with wheels. The situation is different regarding a track?

 

[russ_watters]

Track friction is really constant? According to this source:

An increase in the lift coefficient will result in a decrease of rolling friction.

Tough one. It also says the lift during the takeoff run can vary widely based on the design. My assumption was that lift should remain negligible to small to keep drag down. But anyway, to answer that then, you'll need to know the details of the takeoff run configuration. Did the Wright Flyer rotate or was it oriented at takeoff attitude while sitting on the rail?

The situation is different regarding a track?

No, it's the same issue.

 

[MarceloJenisch]

Did the Wright Flyer rotate or was it oriented at takeoff attitude while sitting on the rail?

It rotated.

Talking about friction again: as an aircraft gains airspeed, its weight is progressively relieved from the wheels (the Flyer actually had wheels, albeit on a track), that's why the friction would be less as the airspeed went up. If anyone has any objections to this and other concepts, please, tell me. My goal with this thread is to play the devil's advocate to try to find out if the Wright Flyer would have been capable of taking off without wind *if* it had a longer track.

 

[Lnewqban]

It rotated.

Talking about friction again: as an aircraft gains airspeed, its weight is progressively relieved from the wheels (the Flyer actually had wheels, albeit on a track), that's why the friction would be less as the airspeed went up. If anyone has any objections to this and other concepts, please, tell me. My goal with this thread is to play the devil's advocate to try to find out if the Wright Flyer would have been capable of taking off without wind *if* it had a longer track.

As friction decreases with speed, both types of drag increase to the square of the increasing taking off speed.
Lift force going up comes from the limited pulling force of the propeller, which may or not be stalling for certain range of speeds.

What you are trying to estimate is very difficult.
The brothers had some good reasons to trust their gravity fed catapult rather than the gusty wind.
It was probably very time consuming to wait for the wind direction to perfectly align with the rail direction.

You surely know everything about it, but let me link some references to the development process for other members:

https://en.m.wikipedia.org/wiki/Wright_Glider

https://en.m.wikipedia.org/wiki/Wright_Flyer

https://en.m.wikipedia.org/wiki/Wright_Flyer_II

https://en.m.wikipedia.org/wiki/Wright_Flyer_III

:)

 

[russ_watters]

Talking about friction again: as an aircraft gains airspeed, its weight is progressively relieved from the wheels (the Flyer actually had wheels, albeit on a track), that's why the friction would be less as the airspeed went up. If anyone has any objections to this and other concepts, please, tell me.

It's correct conceptually, but the question is: how much? Given that it rotated, the answer must be not much normal force reduction.

What you are trying to estimate is very difficult.
The brothers had some good reasons to trust their gravity fed catapult rather than the gusty wind.
It was probably very time consuming to wait for the wind direction to perfectly align with the rail direction.

I agree, their actions tell the tale here easier than we can guesstimate the math. If they thought there was even a small chance that adding a hundred feet of rail would have enabled it to get airborne in Dayton they wouldn't have worked so hard to relocate the operation hundreds of miles to a place with stronger and more reliable winds.

 

[FactChecker]

As friction decreases with speed, both types of drag increase to the square of the increasing taking off speed.

True, but so does lift force and therefore the weight on wheels.

What you are trying to estimate is very difficult.

Yes. I think this is about all we can say without doing experiments to replicate the situation. So we should probably leave it there.

 

[MarceloJenisch]

I agree, their actions tell the tale here easier than we can guesstimate the math. If they thought there was even a small chance that adding a hundred feet of rail would have enabled it to get airborne in Dayton they wouldn't have worked so hard to relocate the operation hundreds of miles to a place with stronger and more reliable winds.

Well, they were still using the glider back in 1903. Also, a strong headwind made the operation much safer if an accident occurred. Therefore, I think those things still justified going to Kitty Hawk.

In 1904 to cut costs, they started to fly in a cow pasture called Huffman Prairie, near Dayton. The place had an altitude of some 800 feet and weak winds. They suffered a lot until the catapult was devised later in that year. Nevertheless, I'm confident the Flyer II could take off without wind. My reasoning is due to a letter Wilbur sent to Octave Chanute (a famous aviation name of the time). I will post an excerpt of it:

"We have found great difficulty in getting sufficient initial velocity to get real starts. While the new machine lifts at a speed of about 23 miles, it is only after the speed reaches 27 or 28 miles that the *resistance falls below the thrust. We have found it practically impossible to reach a higher speed than about 24 miles on a track of available length, and as the winds are mostly very light, and full of lulls in which the speed falls to almost nothing, we often find the relative velocity below the limit and are unable to proceed"

Source: https://invention.psychology.msstat...Chanute_Wright_correspond/1904/Aug8-1904.html

* Wilbur's mention that the ''resistance falls below the thrust'' was a common misconception at the time.

So, the plane could reach about 24 mph on the track alone. It almost achieved flying speed in that way. In another letter, Wilbur mentions a flight made with the Flyer II with an average headwind of only 8 miles:

"In one flight of 39 1/4 seconds, the average speed over the ground was only 33 ft. per second, a velocity only about 3 ft. per second greater than that at starting. The wind averaged *12 ft per second"

* 12 ft per second equals a speed of 8 mph.

Source: https://invention.psychology.msstat...hanute_Wright_correspond/1904/Aug28-1904.html

What does a wind of 8 mph provide to an airplane? Simply an indicated airspeed of 8 mph at the start of the takeoff run. However, the plane could achieve about 24 mph on the track alone. Since it was able to achieve by itself an airspeed speed much higher than the 8 mph wind it proved capable to fly, it was just a question of having a longer track to fly without wind. On the other hand, I'm not sure about the 1903 Flyer having the same capability since its takeoff track never had the length of the one used by the Flyer II. While the track of the Flyer I only had 24 meters (78 feet), the Flyer II had a track that reached 72 meters (236 feet). Why, then, the Wrights did not lay an even longer track and avoid the need of the catapult altogether? The reason was that to lay 72 meters of the track was already a laborious process. Also, the wind changed constantly in Huffman Prairie, to the extent it occurred for the wind to change direction even before the track laying process was finished. The Wrights did not want to risk takeoff with a crosswind, thus they wanted the wind to be aligned with the track. It was more practical, they conclude, to use a catapult and a short track. This doesn't mean the plane was absolutely wind-dependent. It was just easier for them to operate it with the catapult.

 

[berkeman]

Source: https://invention.psychology.msstat...Chanute_Wright_correspond/1904/Aug8-1904.html

Is that your blog? Do you have any other independent references that we can read about your question?

 

[russ_watters]

"We have found great difficulty in getting sufficient initial velocity to get real starts. While the new machine lifts at a speed of about 23 miles, it is only after the speed reaches 27 or 28 miles that the *resistance falls below the thrust. We have found it practically impossible to reach a higher speed than about 24 miles on a track of available length, and as the winds are mostly very light, and full of lulls in which the speed falls to almost nothing, we often find the relative velocity below the limit and are unable to proceed"

Source: https://invention.psychology.msstat...Chanute_Wright_correspond/1904/Aug8-1904.html

* Wilbur's mention that the ''resistance falls below the thrust'' was a common misconception at the time.

No, it's not a misconception. He's telling you the correct answer and you don't want to believe it.

It's called the "drag bucket" or "reverse command area":
http://www.charlesriverrc.org/articles/asfwpp/lelke_airfoilperf.htm

https://www.flightliteracy.com/aircraft-performance-region-of-reversed-command/#:~:text=Flight in the region of reversed command means flight in,in power produces lower airspeed.

 

[jrmichler]

Wilbur's mention that the ''resistance falls below the thrust'' was a common misconception at the time.

Wilbur's mention is a correct conception of thrust required versus airspeed. Every airplane has a speed at which the power required to maintain level flight is a minimum. Above that speed, parasitic drag causes thrust required to increase as airspeed increases. Below that speed, induced drag increases as airspeed decreases. Good search terms to learn more are airplane behind the power curve, and a good hit from that search: https://www.aopa.org/news-and-media/all-news/2013/november/pilot/proficiency-behind-the-power-curve.

 

[cjl]

It's a bit debatable whether the Flyer could take off under it's own power, and maybe even the Flyer II, but I think it's pretty unambiguous that the Flyer III could manage to take off on its own. Given that the Flyer III first flew in June 1905, and Santos-Dumont didn't manage a flight until over a year later, the Wrights were clearly the winners of the first successful heavier-than-air powered flying machine, regardless of whether you consider that to be the Flyer I or the Flyer III. In October 1905, the Flyer III even managed a nearly 40km, nearly 40 minute flight, which makes the FAI's award to Santos-Dumont of the prize for the first 100m flight in November 1906 kind of silly.

In many ways, the Wright's achievements were held back a bit at the time because of their desire for secrecy and their fears of competitors stealing their work. However, it's unquestionable that they were flying tens of miles before anyone else even managed to fly a powered airplane at all.

Also, another question is whether taking off under its own power is even a requirement for the first heavier-than-air powered aircraft. Requiring a catapult for takeoff wouldn't change the fact that it was capable of sustained powered flight without losing altitude, which to me seems sufficient to be the first powered airplane.

 

[FactChecker]

It's my understanding that the greatest advantage that the Wright brothers had was in controlling the flight. Others could fly straight, but the Wright brothers caused a real uproar when they went to France and circled the Eifel Tower with good control. (But I am not an expert in the history of this.)