XP-67 Propeller: Who manufactured the propeller blades?

[PickleJarOfDeath]

Hello,

I have been looking for the aerofoil cross section of the propeller blades used on the XP-67. I determined that the best way to search for this information is to look for the propeller model so I can pin specifics down on that propeller model. I was looking for some propellers on other aircraft to see if there was anything similar and did find that the P-61A and P-61B seemed to maybe have similar propellers. The Curtiss c5424-a10 was used on some while the Hamilton Standards were used on earlier units. Would the Hamilton Standard propellers be commonly used on numerous US aircraft prototypes? As far as I can tell, they were commonly used on a number of aircraft. However, I have found in the general arrangement drawings that I have that the prop diameter is 10 ft 6 in on the XP-67. I am wondering if anyone knows of any props with that diameter. From what I have found, there was a 3 blade Curtiss-Electric propeller assembly of the correct diameter used on the early Mustangs. From my research, Curtiss made a lot of propeller blades for numerous aircraft. I searched for 4 blade Curtiss-Electric propeller 10 ft 6 in diameter. I did not find anything quite yet because I skimmed over the search results without reading more than one article. I will resume my search tomorrow but if anyone happens to find anything in the meantime that would be much appreciated. Below are photos of the XP-67 to help identify the blades.

As for the first three images, they are heavily cropped as distribution/publishing permissions were never detailed when I received these from Boeing's licensing team. No paperwork was involved but to be safe I decided to heavily crop them. The last one I got from Google images. Note: the third image does not include the propeller sheath/cuff at the root of the blade. Because they are unmarked, I was wondering if these were designed and made by McDonnell Aircraft.

 

[Tom Fey]

Definitely a Curtiss Electric propeller. Maybe some additional hints here. If the author Bill Pearce has high res images you may be able to read the Drawing Number on the cuff: 715-1C2-20?
McDonnell Aircraft Corporation XP-67 Fighter

 

[WJPearce]

Very close Tom. Curtiss Electric propeller, Drawing No 714-1C2-30. The props were originally uncuffed, but cuffs were added shortly after the XP-67 was completed. I would assume the cuff were made by Curtiss Electric.

The link below will take you to the LMAL images of engine nacelle testing (including the image further below).
Test 7:1943 - McDonnell XP-67 Bat (or MoonBat) with Continental XIV-1430-17/19 Hyper Engine - NasaCRgis

And below is the image from which I read the Drawing No. The number appears to be the same as that seen on the aircraft after the fire.

https://crgis.ndc.nasa.gov/crgis/images/8/8a/LMAL_33964_McDonnell_XP-67_Bat,_1943.jpg

 

[Tom Fey]

Boom! Thanks for that. Propellers, especially constant speed units, are a complicated art left to propeller makers and not air frame manufacturers. Blade design families ("714") can be modified to achieve various diameters (Basic design diameter minus: "-30").

TF

 

[PickleJarOfDeath]

Boom! Thanks for that. Propellers, especially constant speed units, are a complicated art left to propeller makers and not air frame manufacturers. Blade design families ("714") can be modified to achieve various diameters (Basic design diameter minus: "-30").

TF

Is that -30 from the center to accommodate for a prop hub size? For example there was 714-IC2-12 tested on a P-47C. The P-47 prop hub is definitely smaller than that of the XP-67. Therefore I would imagine the -12 is a smaller subtraction from the center. Because the blades start more off center on the XP-67, I would imagine they just scale the propeller blade to be shorter scale to achieve the same diameter.

 

[Tom Fey]

Is that -30 from the center to accommodate for a prop hub size? For example there was 714-IC2-12 tested on a P-47C. The P-47 prop hub is definitely smaller than that of the XP-67. Therefore I would imagine the -12 is a smaller subtraction from the center. Because the blades start more off center on the XP-67, I would imagine they just scale the propeller blade to be shorter scale to achieve the same diameter.

The "-30" is a reduction in the "base" design of the blade installed diameter, so you have to to know the installed diameter of the "base blade". The subtractions in installed diameter can come from either the root or the tip of the blade. They are "engineering subtractions" that occur before the blade is made and not simply physically cutting sections off or out of the blade. The hubs for a given prop shaft spline size are fairly consistent in size for each manufacturer, and the hub socket sizes are standardized so that different blades can be installed in the same hub to accommodate horsepower or specifications demanded by the air frame (landing gear height; nose contouring, etc). The hubs are complicated, highly loaded, and expensive to make, so "custom" hubs are avoided. They hubs/props/blades also have to pass whirl testing and Type Testing before production use, so they modify designs iteratively based on previous designs that work. Trading of blades and parts can occur within a given manufacturer of props, but you can't take say Hamilton Standard blades and put them in a CE or Aeroproducts hub. see: https://www.enginehistory.org/Propellers/Curtiss/curtissprop.shtml

 

[PickleJarOfDeath]

The "-30" is a reduction in the "base" design of the blade installed diameter, so you have to to know the installed diameter of the "base blade". The subtractions in installed diameter can come from either the root or the tip of the blade. They are "engineering subtractions" that occur before the blade is made and not simply physically cutting sections off or out of the blade. The hubs for a given prop shaft spline size are fairly consistent in size for each manufacturer, and the hub socket sizes are standardized so that different blades can be installed in the same hub to accommodate horsepower or specifications demanded by the air frame (landing gear height; nose contouring, etc). The hubs are complicated, highly loaded, and expensive to make, so "custom" hubs are avoided. They hubs/props/blades also have to pass whirl testing and Type Testing before production use, so they modify designs iteratively based on previous designs that work. Trading of blades and parts can occur within a given manufacturer of props, but you can't take say Hamilton Standard blades and put them in a CE or Aeroproducts hub. see: https://www.enginehistory.org/Propellers/Curtiss/curtissprop.shtml

It wouldn't make sense to truncate the blades anyway but the subtraction I was suggesting was a re-scaling of the blade along a single axis.

Example:

Here is my current representation of the XP-67 which would be using the -30 configuration.

Here is a quick sketch of what I would imagine to be the -12 to be like or anything smaller than -30. This was done to represent the likes of a radial engine aircraft; in particular, the P-47. I just stretched the blades inward basically.

 

[Tom Fey]

It wouldn't make sense to truncate the blades anyway but the subtraction I was suggesting was a re-scaling of the blade along a single axis.

Example:

Here is my current representation of the XP-67 which would be using the -30 configuration.
View attachment 581527

Here is a quick sketch of what I would imagine to be the -12 to be like or anything smaller than -30. This was done to represent the likes of a radial engine aircraft; in particular, the P-47. I just stretched the blades inward basically.
View attachment 581521

Looks very nice. Based on the original photographs, you might consider widening the chord mid span and tapering before and after that. These blades look relatively constant chord,

 

[PickleJarOfDeath]

Looks very nice. Based on the original photographs, you might consider widening the chord mid span and tapering before and after that. These blades look relatively constant chord,

Thank you for the pointer. The next thing for me to do is to find is the drawings or basic specifications at least for these propellers. I am not sure how to go about that though. I had tried searching for a Curtiss archive because that is usually the move that has worked for me.

I went to the National Archives a year ago to collect blueprints and general arrangement drawings. A few months later I searched for a contact to gain info on the McDonnell Douglas Archives as it seemed that they could have the documents from McDonnell Aircraft. I searched Boeing's website, found their licensing team, and was able to request some photos and drawings. They had some great photos but they did say that if there were any drawings, they were proprietary and hence could not be fished from their vaults which was very disappointing.

So my plan is to find a Curtiss archiving location and dig up some information from one of their contacts on the documents that they keep in their collection and if I have to go there in person well then I am screwed because who knows when their region is going to be open to any activity. I was lucky to be taking a gap year so I had the opportunity to really focus on my research between high school and college but this situation has made the rest of the research more difficult. This could probably be more my fault for not going out of my way to try and collect information on the aircraft all around beforehand. I didn't think much of the propellers until I tried getting the information on the aerofoils in terms of a mathematical representation. I also need to have a mathematical representation of the aerofoil of the propellers as well. If anyone knows of any other aircraft that have this propeller, that would be much appreciated (aforementioned P-47 aside).

 

[PStickney]

An easier way would be to dive into the NASA Technical Reports Server : heeps_//ntrs.nasa.gov
and search for "propeller", or "propeller characteristics" or "propeller" "activity factor", and drink from the fire hose.
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093644.pdf provides performance characteristics for Curtiss Electric props, including the 714 series.
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093323.pdf provides information for nearly all Curtiss Electric and HamStan props used in WW 2.
With more searches, you should be able to find blade planforms for specific propeller types.

With the Diameter, Activity Factor, Prop RPM, and assuming a prop Cl of 0.5, and Shaft HP, and the desired True Airspeed and Altitude, you can plug the numbers into the formulae and charts of the Hamilton Standard White Book.
as described in "Advanced General Aviation Propeller Study" and it will give you performance of the prop.
Constant Speed props are easy - they'll adjust pitch to maintain optimum efficiency.

Thank you for the pointer. The next thing for me to do is to find is the drawings or basic specifications at least for these propellers. I am not sure how to go about that though. I had tried searching for a Curtiss archive because that is usually the move that has worked for me.

I went to the National Archives a year ago to collect blueprints and general arrangement drawings. A few months later I searched for a contact to gain info on the McDonnell Douglas Archives as it seemed that they could have the documents from McDonnell Aircraft. I searched Boeing's website, found their licensing team, and was able to request some photos and drawings. They had some great photos but they did say that if there were any drawings, they were proprietary and hence could not be fished from their vaults which was very disappointing.

So my plan is to find a Curtiss archiving location and dig up some information from one of their contacts on the documents that they keep in their collection and if I have to go there in person well then I am screwed because who knows when their region is going to be open to any activity. I was lucky to be taking a gap year so I had the opportunity to really focus on my research between high school and college but this situation has made the rest of the research more difficult. This could probably be more my fault for not going out of my way to try and collect information on the aircraft all around beforehand. I didn't think much of the propellers until I tried getting the information on the aerofoils in terms of a mathematical representation. I also need to have a mathematical representation of the aerofoil of the propellers as well. If anyone knows of any other aircraft that have this propeller, that would be much appreciated (aforementioned P-47 aside).

 

[Skyediamonds]

Tom,
I read your post with great interest. There's a fellow modeler on my RCSB model website who is currently building a large R/C model of the Moonbat. You've presented photos thst ive never seen before. By any chance do you have any other detail photos of this plane? It's been an ongoing great intrigue among us modelers. Any info would be appreciated.
Gary

 

[PickleJarOfDeath]

Tom,
I read your post with great interest. There's a fellow modeler on my RCSB model website who is currently building a large R/C model of the Moonbat. You've presented photos thst ive never seen before. By any chance do you have any other detail photos of this plane? It's been an ongoing great intrigue among us modelers. Any info would be appreciated.
Gary

Gary,

I do believe you are addressing the wrong person. If not, then please correct me. I do only see one photo that he has posted. As for the photos I have posted, you are correct. You will not find them anywhere else online aside from the War Thunder forums where I posted them in a thread there as well. I have a decently large collection of photos and drawings; 19 of which came from the National Archives as well as Boeing's McDonnell Douglas archiving location. These 19 drawings and photos include general arrangement drawings for the aircraft as well as basic designs for the outboard wing panels and tail, and photos of the gear as well as inside the gear wells and some close up photos that could have been taken by walking around the aircraft which includes the nose as well as the interior of the gear wells as well as nacelles from various angles. If any of this could be of use to someone I could potentially send them to whoever needs them. However, I will be sending them directly to the individual who would like to collect such documents.

Dylan

 

[Skyediamonds]

Dylan,
I shall convey your message to Robert. He's the modeler who would most likely be interested. Only potential issue is he may not be a member of this site & therefore not be able to access this post & in turn, directly to you. However, at this time, all avenues should be considered. Thank you for your marvelous reply & a short peek into what you have. For your info: the modeling site is: RCScaleBuilder.com (I think, as I'm reciting from memory). His build thread is XP-67 Moonbat.
Thank you! I shall let you know either way as to what his response is.
Sincerely,
Gary

 

[Skyediamonds]

Robert just responded ( I was surprised that he responded so quickly). His newly registered user name for his site is "Rufe." I'll try to direct him to this post & hopefully you will be able to connect.