Warbird Information Exchange

I was just wondering if anyone out there has access to any blue prints on the F4-U Corsair. I'm wanting to build an ultra light, and just want some plans to go off!!
Any help would be fantastic!!
thanks
Jon

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I never let schooling get in the way of my education - Mark Twain

I have incomlete factory parts and assembly drawings for early F4-U (birdcage). Probably enough to do a good set of scale drawings from. Certainly enough to build a smaller version. But then a "half--fast" three view would also be "close enough". Got a few of those too.
Charlie

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Charles Neely

Might want to ask this guy:

http://www.corsair82.com/

Have visited the 82% Corsair site before and can't make sense of his claim that a "scale wing would be too big". Is he trying to keep a scale- like wing loading? No flame, just trying to understand.

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Charles Neely

Can't say specifically in this case, but an 82% size aircraft probably wouldn't weigh 82% as much as the original. If a Corsair weighs 10,000 pounds (just a round number for an example), an 82% size Corsair would probably weigh 1/3 to 1/2 of that and still have 82% of the wing area. He also plans to fly on an R-985 which has 450 HP, far less than 82% of a real Corsair's 2,000+ HP.

Look for other aircraft in that size range that fly well on 450 HP and see what their weight is. Much less than 8200 pounds I would suspect!

I know that weight does not scale dynamically. Like many variables it is usually a function of some "squared factor" , or other(I'm not pretending to understand the math). But I can comprehend there is no direct corelation between the 82% scale which would automatically be 82% of the full size a/c's wight. Unless I miss my guess, A 450 hp powered "sailplane" would have stellar performance and may not be something to be missed !

As a scale modeler of some limited experience,I feel that a 10% deviation from an otherwise unform scale will look wrong in the air and on the ground, on something as large as the wing of a well known silloeutte. Compromise is the bane of any scale project, be it a Stewart 51 or an 85% Corsair. Up to a point, the larger wing could carry a greater weight with only a marginal loss of top end speed. I also think that a scale airfoil might not be innappropriate for such a project at 82%Perhaps someone with more aerodynamic knowledge could chime in here?
TIA

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Charles Neely

True enough, but if we were to assume the same airfoil section and a similar wing loading (discounting the change in Reynolds number, etc.), are we sure that a builder likely to construct something like this will have the training, expertise, and skill to safely fly it? Maybe a lighter wing loading, a more docile airfoil section, or some additional wing twist would be warranted. Also, the old NACA airfoil series had some notoriously poor stall characteristics compared to modern airfoils capable of otherwise similar performance.

Unless I missed something, the corsair builder is stating a case for avoiding what he percieves to be too light a wing loading for his 85% effort. I don't see it as a problem. A compsite 85%wing could still be made strong enough, to carry it at the speeds dictated by physics

As one scales down, actual speed ranges do not. Like weight , there is no direct scale factor. Smaller versions of their larger selves MUST fly faster than a direct scale speed(the effect of Reynolds numbers, as I understand it). IE a real fighter cruises at 300mph. Its 1/4 scale miniature will fall out of the air at 75MPH(1/4 300mph). Stall and top speed are also relatilvely higher. However, one way to combat "bad stall" chascteristics is to build a lighter airframe. I'm not discounting newer airfoils, but to change the shape too much is to loose the character of the real thing. And that is usually the "WHY" one chooses to model the original in miniature form in the first place.

IF one can build a successful 85% scale miniature that is outwardly identical in most every feature (I know pilot's seat cannot be scaled), I simply ask why not? Aircraft are and always will be a collection of compromises. Some features replaced by "better/more modern" are not nessesarily the best compromise if the existing features are adequate for the task.

The builder makes his case for using the fuselage scale (fits his engine diameter), But in my opinion is weak in his presented reasoning for using the smaller than scale wing. Like I said before, I would like to understand. Also, again, I could be missing something.

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Charles Neely

BTW, I am enjoying the discussion. I will shut up if others will join in!

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Charles Neely

Unless I missed something, the corsair builder is stating a case for avoiding what he percieves to be too light a wing loading for his 85% effort. I don't see it as a problem. A compsite 85%wing could still be made strong enough, to carry it at the speeds dictated by physics

I'm not sure what you are suggesting here, could you elaborate? The builder is choosing to construct this aircraft out of composite materials for ease of manufacture due to the compound curves. Plenty of aircraft have been built in this size range with composite, metal and wooden wings.

As one scales down, actual speed ranges do not. Like weight , there is no direct scale factor. Smaller versions of their larger selves MUST fly faster than a direct scale speed(the effect of Reynolds numbers, as I understand it). IE a real fighter cruises at 300mph. Its 1/4 scale miniature will fall out of the air at 75MPH(1/4 300mph). Stall and top speed are also relatilvely higher. However, one way to combat "bad stall" chascteristics is to build a lighter airframe.

You would have a very hard time building a scale airframe at a scale weight unless you built it from depleted uranium. Can you imagine a 1/4 scale model with a 9' span that weighs 2500 pounds?! You can't just attribute bad stall characteristics to the wing loading either. While it is a factor, the shape of the airfoil section is more important.

I'm not discounting newer airfoils, but to change the shape too much is to loose the character of the real thing. And that is usually the "WHY" one chooses to model the original in miniature form in the first place.

I think the comment was that the planform was changed (reduced in scale more than the fuselage), not the airfoil aerodynamic section itself.

IF one can build a successful 85% scale miniature that is outwardly identical in most every feature (I know pilot's seat cannot be scaled), I simply ask why not? Aircraft are and always will be a collection of compromises. Some features replaced by "better/more modern" are not nessesarily the best compromise if the existing features are adequate for the task.

He is not building a miniature. He is not scaling down an R-2800 and he is not building it primarily out of sheet metal. He is designing a sport aircraft that meets his requirements for flying qualities, cost, and ease of construction. This aircraft just happens to be designed to look like a Corsair. I don't see that his compromises are unreasonable. We can all subjectively judge the apperance when the plane is done.

The builder makes his case for using the fuselage scale (fits his engine diameter), But in my opinion is weak in his presented reasoning for using the smaller than scale wing. Like I said before, I would like to understand. Also, again, I could be missing something.

All I can say is that it is unfair to second guess the compromises made by the designer, especially since we don't know what they all are, we are only assuming. This is a man-carrying airplane and he plans to strap his a$$ into it. I also don't see how he has a need to defend his reasoning since his website is only a builder's log not a step by step design manual for subscale replica aircraft.

I have seen lots of pipe dream aircraft on the internet and in person. This one appears to be well designed and researched from an engineering standpoint, and the man is taking his time and re-doing things that don't turn out the way he wants. I wish him well and think the airplane looks great!

You might also want to research Marcel Jurca's designs as well as those of WAR Aircraft Replicas. Feel free to compare those aircraft with this one and let us know what you think!

Wow! Not trying to upset anyone's plan to do and/or present what ever they want. I hope you don't think I'm attacking him or his project in any way.
It's a great project. I really like it. I wish him ALL success. He wants to use a different airfoil, so be it. It is, after all, his chioce. Also, as is his perogitive, it was he that created the website, to be viewed by the public.
You are absolutely right. The 82% effort represents a new aircraft, period.

HOWEVER the website couches the entire project as a scale representation of a full size prototype. I simply questioned his stated logic for using a smaller than scale wing. Please pardon me for assuming that commenting on a percieved illogicallity deserves to be intelligently discussed on the internet, especially among aircraft buffs/aviators, etc.
What the hell was I thinking?

PS I haven't disscused anything among operators of any WAR aircraft. But I have discussed the flying properties of several scaled projects with their pilot's/operators (mostly Sewart 51's). Not a one wishes for less wing loading. Imagine that?

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Charles Neely

Excuse me I meant to say a higher wing loading. Imagine that?

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Charles Neely

No, I think they are fair questions. It is just hard to second guess someone else's efforts without hearing it first hand. I've never met the guy but have been following the project over the past few years. It appears to be well thought out, so not knowing any better I can only guess that he used the same skill sets in selecting the wing area.

You probably have a better feel for scaling with regard to appearance than I do, but I'm willing to wait and see. Since I would never have the time to build something like that, I am content to just watch from the sidelines.

As it happened, I came accross a 3-view of WAR's FW190, this morning. It's in Jack Lambie's book re: composite a/c structures. Sure appears to me that the wing plan form is larger than proportional to "scale".

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Charles Neely

Possibly. Shorter aircraft usually need greater than scale horizontal stabilizer area to provide adequate stability. That may make it look so. Also, the fuselage is wider than scale to accomodate the pilot, so that may warp the perception a bit. Keep in mind also that the WAR Aircraft Replicas were all designed around a common fuselage structure (and common wing structure except or the Corsair). You can tell that it is intended to reprsent a Corsair or FW-190, but not many would be fooled although I think a couple of the FW-190s were used in a movie about the Kennedy's along with a B-24.