1/2 scale warbirds

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Riggerrob

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I've thought about something like a 3/4 scale Wildcat quite a bit. And let's be honest, 3/4 Wildcat is more-or-less around a 50% warbird anyway so...
I guess one thing I wonder is how much do people seem to care about a nice round-number scale factor? It never made much sense to me to live with certain constraints just to keep the scale at 1/2 or 3/4 or 5/8. If it's actually 53.7% scale that's fine by me.
Dear ScaleBirdsScott,
You are showing your age.
You cute little puppy.
Hint: I love playing with puppies.

Exact half-scale was easier to calculate before electronic pocket calculators were invented (early 1970s).
People who insist on rigidly sticking with a simple fraction are just showing their age.
Hah!
Hah!
I was born in 1957 and graduated high school in 1974 when teachers were loudly debating banning pocket calculators from final exams because they were considered "cheating."

Now you just type in a constant when down-sizing from original drawings.
Mind you, some of the originals lacked stability and were difficult to maneuver, so smart modern designers enlarge control surfaces, adjust airfoils, angles of incidence and shift centers of gravity to tame flight characteristics. Fore example, they poster who is currently drafting a sub-scale replica of a Focke-Wolf Ta-152 would be wise to modify its wing airfoils to tame the originals' abrupt stall ... with flaps up.

Yes, all those Walter Mitty types think they want an exactly half-scale replica, but most only have the flying skills acquired during recent lessons in "tame" Cessna trainers. Ergo, the better flying sub-scale replicas are more "stand-off scale."
 
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flitzerpilot

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The Hurricane achieved some stability through the use of the reflexed Clark YH section which allowed a relatively small tailplane. I remember seeing an Army DH Beaver being displayed many years ago at a Battle of Britain air display and the commentator extolling its virtues of manoeuvrability, ie. its tight turn capability. Next on was a Hurricane which promptly demonstrated a much tighter turn capability!

The Wildcat seems admirably proportioned for down-scaling and degree of wing taper is minimal - if that's a serious concern among would-be sport-flying fighter pilots. Equally the Brewster Buffalo with a useful contender with its large amount of glazing, although as has been mentioned, the undercarriage could be problematic. One of the best would be the fixed-undercarriage Fokker D.XXl, brilliantly flown in the Winter War against the USSR. I already have the flat-topped spar booms which I prepared years ago for some cantilever biplanes, such as the Fokker D.Vl or D.Vll, or the Raab-Katzenstein Kl.1 Schwalbe or RK 26. The same deep box spar (at its full width of 2-1/4") would serve equally well for the D.XXl at around 21' span, with additional capstripping on the upper spar surface to achieve the correct dihedral for that type - unnecessary with the biplanes mentioned above.

I'm pretty sire I have sent side elevations of my original drafts for this type in previous posts.
 

cluttonfred

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+1 on the Fokker D.XXI, I really like its simplicity and transitional interwar styling much like a Hurricane or the M.S. 405/406. 50% scale would be tough, though, as that would leave an 18' 1/2" span and just 43-1/2 sq ft of wing area and it might be tough to fit the pilot in there. 67% scale (24' span and 77 sq ft) would give you a hot sport plane roughly equivalent to a Formula V racer. 75% scale (27' span and 98 sq ft) would give you a docile fun flyer along the lines of a Jodel D.9 Bébé.
 

Riggerrob

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" ... The Wildcat seems admirably proportioned for down-scaling and degree of wing taper is minimal - if that's a serious concern among would-be sport-flying fighter pilots. Equally the Brewster Buffalo with a useful contender with its large amount of glazing, although as has been mentioned, the undercarriage could be problematic. .... I'm pretty sire I have sent side elevations of my original drafts for this type in previous posts."
A Brewster Buffalo sub-scale replica would suffer the same interference problems as a Wildcat replica. Rudder pedals would interfere with landing gear retraction.
The pilot's femurs would interfere with wing spars. You could install a ring spar or ring bulkhead to carry main spar loads across the fuselage, but would need some sort of dished rear spar to pass below the pilot's buttocks which would need to be deep in the fuselage, below the wings' bottom skin. Structurally it would not be impossible, just heavier and more complex.
 

cluttonfred

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I don't know about the Buffalo, but for the Wildcat it's not as bad as you'd think. Here's a Soneria 1 and an FM-2 Wildcat at the same length, which works out to be about 58% scale.. You can see that the wing is much lower compared to the canopy so I think you could put the pilot's rear end between the front and rear spars and knees up and over the front spar. If like me and unlike Scott ;-) you are a sucker for a nice fraction, you could go with 5/8 scale to get some additional wiggle room. That would be give you 23' 9" span of , 18' length, 5' 9" height, and a civilized 102 sq ft wing area. Keeping in mind that the Double Wasp engine had a 48" diameter, that means 30" width inside the cowling and even more in the cockpit. Sign me up!

Sonerai 1 and FM-2 Wildcat.jpg
 

Hawk81A

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Again, as I have said - for a 1/2 SIZE (not scale) consider the KR1 / KR2 as a starting point. You will be adding belly structure (or fairing BELOW the floor. I kind of started this thought pattern back in the'80s while looking at a plywood 30'' hose spool. I was thinking the 30'' would fit a VW engine. On the 'Cat, it tapers DOWN from the firewall with an extra drop for the lower gear fairing.
The Buffalo looks like a flying barrel anyway. Dennis
 

Riggerrob

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I don't know about the Buffalo, but for the Wildcat it's not as bad as you'd think. Here's a Soneria 1 and an FM-2 Wildcat at the same length, which works out to be about 58% scale.. You can see that the wing is much lower compared to the canopy so I think you could put the pilot's rear end between the front and rear spars and knees up and over the front spar. If like me and unlike Scott ;-) you are a sucker for a nice fraction, you could go with 5/8 scale to get some additional wiggle room. That would be give you 23' 9" span of , 18' length, 5' 9" height, and a civilized 102 sq ft wing area. Keeping in mind that the Double Wasp engine had a 48" diameter, that means 30" width inside the cowling and even more in the cockpit. Sign me up!

View attachment 128091
Perhaps your ideas might work.
I started by noticing that the original pilot seat sat almost on the wings' top skin, so a quick calculation put it near the bottom of a half-scale fuselage.
You might need to pound some dents in the firewall to accept rudder pedals. Mind you, that wide firewall would make it a bit easier to mount rudder pedals outboard of the carburetor, etc.
Perhaps I am worrying too much about my SAE 95th percentile male legs (32 inch inseam).
Many of these scale replicas (e.g. WAR) are fine for smaller men, but too tight on me.
 
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Hawk81A

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Yeah. Try being 6'4''. They did manage to cram me into the original KR1-B. They removed the back seat cushion, and I had my head tucked down into my knees though. I've always viewed the KR series as a "flying go kart". The WAR planes are probably about the same. I do seem to recall that there were "stretch" plans for the KRs that had an extra foot in front of and behind the main spar. Dennis
 

opcod

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Funny read.. Do 1 true hard landing and you will understand for very long time: that not having proper seat and space foam is something that is mandatory. safety first. But anyway, no chute in most plane as well, but should also be like the second item in the design.
 

Battler Britton

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+1 on the Fokker D.XXI, I really like its simplicity and transitional interwar styling much like a Hurricane or the M.S. 405/406. 50% scale would be tough, though, as that would leave an 18' 1/2" span and just 43-1/2 sq ft of wing area and it might be tough to fit the pilot in there. 67% scale (24' span and 77 sq ft) would give you a hot sport plane roughly equivalent to a Formula V racer. 75% scale (27' span and 98 sq ft) would give you a docile fun flyer along the lines of a Jodel D.9 Bébé.


And..

Marcel JURCA started all with the Jodel D9 / D 112 technology, the MJ2 (Tempète) was basicaly a heavy D112, inside.
at that time (1952), people were criticizing the fact he made a single seater with the power for a 2 seater..
(the first Tempete flew with 65 hp!!)
The MJ2 lead to the Sirocco then the first true mustang replica, 2/3,(early 60') and you know the story, after that!
so, it is not fake to say that so much modern replica were born after the Jodel Bébé! (lol!)
The same with Rand/Robinson, they opened the door for WAR...

the KR 2, in a single seater mod is a great starting base.


And now.. happy to have Lynn Williams and ScaleBirdscott !!
 
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cluttonfred

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And..

Marcel JURCA started all with the Jodel D9 / D 112 technology, the MJ2 (Tempète) was basicaly a heavy D112, inside.
at that time (1952), people were criticizing the fact he made a single seater with the power for a 2 seater..
(the first Tempete flew with 65 hp!!)
The MJ2 lead to the Sirocco then the first true mustang replica, 2/3,(early 60') and you know the story, after that!
so, it is not fake to say that so much modern replica were born after the Jodel Bébé! (lol!)
The same with Rand/Robinson, they opened the door for WAR...

the KR 2, in a single seater mod is a great starting base.


And now.. happy to have Lynn Williams and ScaleBirdscott !!

And the KR-2 is based on the KR-1, which I have always heard was largely based on the Taylor Monoplane but with foam over the basic wooden structure and retractable gear.

taylor mono cutaway.jpg Cutaway_KR-1.jpeg
 

Hawk81A

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Workmanship looks impeccable. Got curious about engine and found his many videos. It's a Subaru conversion, maybe EA81?. I'm not that familiar with older Subies. Dennis
 
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radfordc

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In the video he purposely doesn't say what it weighs, only that the CG is good. I wonder if that means anything? I hope he has been honing his flying skills along with his building expertise.

Also, I noted the comments about toe-in vs toe-out on the LG. My Sonex was designed with toe-in, but he says that toe-out is better. What do the original WAR planes use?
 

BJC

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In the video he purposely doesn't say what it weighs, only that the CG is good. I wonder if that means anything?
Most homebuilts weigh more than the factory prototypes.

Those elaborate paint jobs, multi-EFIS panels, and attendant electrical systems with dual batteries, and fancy interiors add significant weight. I do know of two people who built Pitts S-1S’s lighter than the factory airplanes, though.


BJC
 

Pops

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Most homebuilts weigh more than the factory prototypes.

Those elaborate paint jobs, multi-EFIS panels, and attendant electrical systems with dual batteries, and fancy interiors add significant weight. I do know of two people who built Pitts S-1S’s lighter than the factory airplanes, though.


BJC
No one has built a 4 seat Bearhawk as light as Bob Barrows in building #1. Closest one I know of was 40lbs heaver. He said he could have made the seats lighter. I have flown #1 with Bob. He said to stall it. I got it down to where I thought the stall would be and he said let me show you something. He took over and kept bringing the nose up and then adding a little power. Hanging on the prop and then started doing tight figure 8's with the rudder with the airspeed on Zero.
 

pylon500

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Workmanship looks impeccable. Got curious about engine and found his many videos. It's a Subaru conversion, maybe EA81?. I'm not that familiar with older Subies. Dennis
EA81 is about the lightest of the Subi's used in aircraft, being single cam with pushrods. Only 1800cc (stock), but good for 100~180hp, depending on how you tweak it.
Flown a KR-2 with a normally aspirated, belt reduced EA-81, and could easily believe it was putting out 120hp. Combined with the reduction drive and suitably bigger prop, it had a lot more pull than a Jabiru 3.3.
KR-2SX.png
I didn't build this, only test flew.
 
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