Research/theory on propeller shapes and airfoils?

[spicmart]

Is there any (documented) research and development on different propeller airfoils and shapes on either side? Or can anybody explain the theory behind them?

It would be interesting to know how those came to be. Especially the difference when comparing the rather curved, rounded German prop blades with the more square Anglo-American ones.

Afaik British, American and German propellers seem to have been the most advanced with Japanese and Russians ones somewhat lacking.

 

[Aeroweanie]

Early props mostly used Clark Y and RAF6 airfoil sections, but these airfoils didn't have good transonic performance, important near the tip of a blade. The NACA 16-series airfoils were found to have good transonic performance and were the standard prop airfoils well into the 1970s. Hartzell, McCauley, Hamilton-Standard and Dowty all developed new prop airfoils in the early 1980s that are still used today.

 

[mjfur]

https://catalog.archives.gov/search?q=propeller&recordGroupNumber=255

 

[Tony Kambic]

Expensive ($135 on Amazon) but NASM Curator Jeremy Kinney authored this book:

Reinventing the Propeller: Aeronautical Specialty and the Triumph of the Modern Airplane
Brief: An international community of specialists reinvented the propeller during the Aeronautical Revolution, a vibrant period of innovation in North America and Europe from World War I to the end of World War II. They experienced both success and failure as they created competing designs that enabled increasingly sophisticated and 'modern' commercial and military aircraft to climb quicker and cruise faster using less power. Reinventing the Propeller nimbly moves from the minds of these inventors to their drawing boards, workshops, research and development facilities, and factories, and then shows us how their work performed in the air, both commercially and militarily. Reinventing the Propeller documents this story of a forgotten technology to reveal new perspectives on engineering, research and development, design, and the multi-layered social, cultural, financial, commercial, industrial, and military infrastructure of aviation.

 

[bf109xxl]

 

[bf109xxl]

Afaik British, American and German propellers seem to have been the most advanced with Japanese and Russians ones somewhat lacking.

Could you please demonstrate this by numbers?

 

[swampyankee]

Is there any (documented) research and development on different propeller airfoils and shapes on either side? Or can anybody explain the theory behind them?

It would be interesting to know how those came to be. Especially the difference when comparing the rather curved, rounded German prop blades with the more square Anglo-American ones.

Afaik British, American and German propellers seem to have been the most advanced with Japanese and Russians ones somewhat lacking.

I'm sure there are. Some are, of course, proprietary, but try Aerade, from Cranfield, and NASA's NTRS (ntrs.nasa.gov). AIAA also has some, but they're all paywalled.

 

[MIflyer]

The original book on the subject, by the guy who also designed the Ercoupe, the Piper Cherokee, and the Cessna Agwagon.

Aircraft Propeller Design : Fred E. Weick : Free Download, Borrow, and Streaming : Internet Archive

Book Source: Digital Library of India Item 2015.163729dc.contributor.author: Fred E. Weickdc.contributor.other: Indian Institute Of Sciencedc.date.accessioned:...

archive.org

A US Army report on propeller design: DTIC AD0774831: Summary of Propeller Design Procedures and Data. Volume 1. Aerodynamic Design and Installation : Defense Technical Information Center : Free Download, Borrow, and Streaming : Internet Archive

Interestingly enough the Wright Brothers did an excellent job of designing their own propellers. Had they pursued that as a commercial business they would have had much better success rather than trying to patent the concept of three axis control. We'd likely have a Wright Propeller Company still today.

 

[Aeroweanie]

Hank Borst was an important contributor in propeller development. He rose to be the chief aerodynamicist at the Curtiss-Wright propeller division and later was Director of Preliminary Design at Boeing Vertol. After leaving BV, he worked as a consultant. Among his clients was McCauley Propellers (and I think Aeroproducts). I have some propeller layout sheets from his archives.

Defense Technical Information Center

apps.dtic.mil

Defense Technical Information Center

Rose Worobel was an important propeller aerodynamicist at Hamilton Standard from 1943 to 1977:

Computer program user's manual for advanced general aviation propeller study - NASA Technical Reports Server (NTRS)

A user's manual is presented for a computer program for predicting the performance (static, flight, and reverse), noise, weight and cost of propellers for advanced general aviation aircraft of the 1980 time period. Complete listings of this computer program with detailed instructions and samples...

ntrs.nasa.gov

Advanced general aviation propeller study - NASA Technical Reports Server (NTRS)

Sensitivity analysis of advance propeller configurations designed for general aviation aircraft of 1980 time period

ntrs.nasa.gov

Q-FANSTM for general aviation aircraft - NASA Technical Reports Server (NTRS)

Continued growth of general aviation over the next 10 to 15 years is dependent on continuing improvement in aircraft safety, utility, performance and cost. Moreover, these advanced aircraft will need to conform to expected government regulations controlling propulsion system emissions and noise...

ntrs.nasa.gov

Advanced general aviation propeller study - NASA Technical Reports Server (NTRS)

Methods for predicting the performance, noise, weight, and cost of propellers for advanced general aviation aircraft of the 1980 time period were developed and computerized. This basic program was refined to incorporate a method of including the blade shape parameter, integrated design lift...

ntrs.nasa.gov

 

[MIflyer]

It's been pointed out that early in the war German props often had much broader chord blades than did American ones. Later American props began to feature broader chords, most notably with the later propellers used on the P-47, which improved its performance so much. Broader chord props were also visible on the P-51H and P-82 and even when the T-28A came out a few years after the war it had what was called a "butter paddle" prop. American props also gained cuffs around the base of the blade, which not only increased the chord but also improved the streamlining at the base of the blade, from a more or less circular cross section to more of a teardrop shape. After WW2 you saw less use of cuffs on US props, apparently because water collected between the cuff and the blade and caused corrosion, but I think the KC-97 kept using cuffs right up to its removal from service in the mid-70's.

I wonder if the broader chords of US props reflected an appreciation of superior performance of German props or rather increasing horsepower of later American engines? The Germans started out with significantly larger displacement engines than the US or British were using.

The Japanese seemed to have relied on license built versions of US props. When Koga's Zero was captured and rebuilt a US prop was fitted with no problems.

 

[swampyankee]

I think the broader chords of German propellers were sometimes because their smaller aircraft forced smaller prop diameters (although I've not actually gone through the data), but more because they stuck to fewer blades than did the RAF or US, as the latter two pretty much abandoned synchronized guns. Gun synchronization is more difficult with more blades and causes disproportionately larger reduction in rate of fire. If you have a fixed diameter and need a blade area of x, a prop with three blades will have broader chord than one with four.

I also suspect the "better performance" of German propellers is not demonstrable by data.

 

[SaparotRob]

Does anyone know the official name of the "paddle blade " props? Paddle blade just doesn't sound DoD enough.

 

[spicmart]

Could you please demonstrate this by numbers?

Can't. Just read a couple of times that they were not just as good. Neither had many specialized high-altitude aircraft. That may be the reason..?

 

[MikeMeech]

Is there any (documented) research and development on different propeller airfoils and shapes on either side? Or can anybody explain the theory behind them?

It would be interesting to know how those came to be. Especially the difference when comparing the rather curved, rounded German prop blades with the more square Anglo-American ones.

Afaik British, American and German propellers seem to have been the most advanced with Japanese and Russians ones somewhat lacking.

Hi
The basic information for reasons for shape and number of blades can be found in 'Mechanics of Flight' by A C Kermode, in Chapter 4 'Thrust':

I hope that is useful.

Mike

 

[Engineman]

I think the broader chords of German propellers were sometimes because their smaller aircraft forced smaller prop diameters (although I've not actually gone through the data), but more because they stuck to fewer blades than did the RAF or US, as the latter two pretty much abandoned synchronized guns. Gun synchronization is more difficult with more blades and causes disproportionately larger reduction in rate of fire. If you have a fixed diameter and need a blade area of x, a prop with three blades will have broader chord than one with four.

I also suspect the "better performance" of German propellers is not demonstrable by data.

I agree that finding the technical data to fully compare some of the Allied and Axis propeller performance would seem to be quite a task. Reading wartime technical reports on propellers does not usually provide all the detail that you might expect, so that can leave us with the overall flight performance to try and judge.
The German late-war propellers seem to have had good performance. The Do 335 and Ta 152 types are good examples, having some of the best performances in speed and high altitude. The propeller types were 3-bladed; VDM on the DB powered versions and Junkers on the Jumo engines. The blades were broad chord, usually alloy on VDM and compressed wood on the Junkers. Overall, it seems to me that these German designs were right up there with performance, while also integrating synchronised guns and Motor cannon.

Eng

 

[MIflyer]

Interestingly enough, the Avro Manchester was one of the very few British built aircraft for its time that had fully featherable props. The idea of a multi-engined aircraft without props you could feather seems very basic from the American viewpoint. The consequences of losing an engine and having to put up with a windmilling prop are grim. The Manchester was chosen to simulate enemy gliders coming in from high altitude because it could feather the props, unlike most British built aircraft of the time.

Aside from such props, the USA and UK had different ideas about the need for pressure injection carbs and radios in training aircraft. US aircraft had radios except for primary trainers and the RAF even flew the more advanced trainers to overseas destinations without radios.

 

[spicmart]

Once read that late-war German props (wooden?) were better for climb and Allied metal props better for top speed.
One experimental Me 109K had a thin metal prop which increased speed by over 12 km/h iirc.

 

[spicmart]

Quite a difference in blade shape from P-51 propeller and a VS-9 used on the Fw 190D-13 and Ta 152 . Wonder what the rationale behind (the German design) was?
Second image by Jerry Crandall.

 

[bf109xxl]

Can't. Just read a couple of times that they were not just as good. Neither had many specialized high-altitude aircraft. That may be the reason..?

The Soviets experimented quite extensively with propellers during the war. In particular, four-bladed propellers were developed for the Yak-7, Il-4, Il-2, etc. along with the propellers with wider blades (292 mm instead of 260 mm) for the Il-2 and Li-2. All of them gave a gain mainly only on takeoff, reducing the take-off roll. However, at altitude the differences from serial propellers were minimal, with frequent problems with overspeeding. In addition, the Soviets also experimented with purchased/trophy German airplanes, swapping German propeller blades for Soviet ones and vice versa - installing blades from German to Soviet. Additionally, the Soviets had purchased licenses for some Hamilton Standard propellers (possibly one) even before the war.
Until the end of the war, the Soviets had no particular need for high-altitude fighters, but they were still developing them, and some had propellers with wide paddle-shaped blades (e.g., I-224). The Soviets' main problems were not with aerodynamics - they had a number of good specialists on this field (Maikapar, Yur'ev, etc.), but more with the mechanics of blade control, speed control, etc. due to a significant lower technological level.

 

[spicmart]

The Soviets experimented quite extensively with propellers during the war. In particular, four-bladed propellers were developed for the Yak-7, Il-4, Il-2, etc. along with the propellers with wider blades (292 mm instead of 260 mm) for the Il-2 and Li-2. All of them gave a gain mainly only on takeoff, reducing the take-off roll. However, at altitude the differences from serial propellers were minimal, with frequent problems with overspeeding. In addition, the Soviets also experimented with purchased/trophy German airplanes, swapping German propeller blades for Soviet ones and vice versa - installing blades from German to Soviet. Additionally, the Soviets had purchased licenses for some Hamilton Standard propellers (possibly one) even before the war.
Until the end of the war, the Soviets had no particular need for high-altitude fighters, but they were still developing them, and some had propellers with wide paddle-shaped blades (e.g., I-224). The Soviets' main problems were not with aerodynamics - they had a number of good specialists on this field (Maikapar, Yur'ev, etc.), but more with the mechanics of blade control, speed control, etc. due to a significant lower technological level.
View attachment 834962

The blades on the foto has clipped tips similiar
to a German VS-9 prop with such as well.