The A-4 Skyhawk

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Bigshu

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My recommendation is to not attempt a scaled down A-4. The A-4 was a great plane because it was designed to get the job done with the most simple and minimal aircraft and expense. You would do better to scale the design philosophy rather than scale the airframe. Look into an A-4 inspired design. Many of the A-4's aesthetics can be transferred to the new design. It won't look like a small clone of the A-4, but it will be obvious that it shares a lot of design DNA with your favorite aircraft.
I agree with this sentiment. I always liked the A-7 and F-8. I've often wondered if I could modify a Taylor mini-imp to resemble either of them.
 

Vigilant1

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You would do better to scale the design philosophy rather than scale the airframe. Look into an A-4 inspired design. Many of the A-4's aesthetics can be transferred to the new design. It won't look like a small clone of the A-4, but it will be obvious that it shares a lot of design DNA with your favorite aircraft.
I suspect this would be the best bet. There are a lot of distinctive A-4 visual cues that could be included in an A-4 "tribute" design. The hump. The markings. Those intakes (modified to reduce drag). The delta wing planform (but stretched a bit in span). I'd even consider keeping the refueling probe (repurpose it with pitot and static ports?). It would be a tip of the hat to the "scooter" and yet allow flight at 40gph instead of 800 gph.
 

Angusnofangus

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I sat in an A4 a couple years ago. I'm 5'10" and 175lbs. Don't know how anybody fit in them. A Bf 109 would be more comfortable.

Rob
The Navy 'A' school that I went to in 1969 had 3 or 4 A-4's as maintenance trainers. I sat in them numerous times, and at 6' and 205 lbs, I remember it being snug, but no too tight.
 

N804RV

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I went to O-level maintainer school on the A-4 many (many) years ago, in Meridian, MS. My first tour was with VC-5 at NAS Cubi Pt. As an avionics tech, I was so bored, I volunteered to fly and that was a whole 'nother story.

But, I'll always have fond memories of working on that airplane and doing detachments to Kadena airbase to maintain them during the many exercises they participated in during peacetime Navy ops.
 

BJC

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I suspect this would be the best bet. There are a lot of distinctive A-4 visual cues that could be included in an A-4 "tribute" design. The hump. The markings. Those intakes (modified to reduce drag). The delta wing planform (but stretched a bit in span). I'd even consider keeping the refueling probe (repurpose it with pitot and static ports?). It would be a tip of the hat to the "scooter" and yet allow flight at 40gph instead of 800 gph.
What engine are you guys think of for a scaled, or look-alike, A4?


BJC
 

TarDevil

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On of my favorite homebuilts is the Prowler Jaguar. It's arrival at Oshkosh evoked a lot of remarks about how it looked a little like this or that warbird. I can see this as just such a project... melding the sweetest characteristics of the early jets.
 
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Vigilant1

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What engine are you guys think of for a scaled, or look-alike, A4?


BJC
I don't follow the development of these engines closely. Maybe the PBS TJ_100 as on the SubSonex? About 290 lbs of thrust (for TO) and a specific fuel consumption of about 1.14 lb/lbf/hr (so, about 38 gph if an avg of 200 lb of thrust is used). Just not much thrust and burns a lot of fuel to achieve it.
To make it work, the plane would need a fairly low span loading and would need to be clean. A scale A-4 Douglas Skyhawk jet that struggles to outclimb the Cessna Skyhawks already in the pattern will be a source of endless derision.
 
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shadow

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Contact Magazine had an issue devoted to a small A-4 using a Corvette ZR-1 engine and a Q-Fan. It was an Embry Riddle class project.
Issue #26, description: The MINI-HAWK is a 2./3 scale jet fighter concept proposed by Embry-Riddle University, using a Chevy engine driving a fan.
 

vhhjr

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I would love to be the first to do it, but the odds are against it. So far, no one has successfully built a ducted fan powered replica. Even the Jet Hawk, which sold an untold number of plans sets, hasn't appeared at any fly-in that I've been to or read about. I thought the replica Russian fighter might make it, but it has been very quiet for a couple years. I'd better get back to my rolling DF test stand.
 

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txkflier

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I flew an A-4E Skyhawk today. It was a little over 56 inches long, had a wingspan of 37 inches, weighed about 5 lbs, and was powered by an 80mm ducted fan running on 24 volts. I purchased it in October 2017 and have hated it ever since. Yes, it's a neat-looking plane, but it does not fly well at all. Since the fuselage sits on top of the wing and the horizontal stab is mounted thru the vertical fin, it's terribly top-heavy. It would rather be inverted than right-side-up. The delta wing provides no roll damping at all and makes it hard to determine the bank angle at the perimeter of the field. I fly it using a receiver that has a built-in gyro that will limit the bank angle to 85 degrees and automatically level the plane when I let go of the stick. I reprogrammed the gyro settings today and made three pretty decent flights.. ;-)
 

Traskel

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Fun discussion and great nostalgic video- Thanks. A question - It seems to me that the Viper Jet is a good example of the diminishing returns of down-scaling performance Jet Aircraft. Even their greatly improved MK2 version with stellar performance and (as reported) great overall handling is very tough to travel anywhere in due to the fuel burn rate verses capacity.

Even the comparatively meek Sonex Jet is limited to 200 miles per hop. Jets just gobble fuel so fast that even though we'd like there to be a baby fighter jet to build doesn't that scaling factor impact the reality to a point of severe impracticality?

Sure if I could afford a million bucks to spend on an plane and $20/minute to fly it the Viper or an A4 derivative would be a blast but I could get a 92' Shorts Tacono for $1M and have a usable range and 95% of the fun.. I know this is a builders forum so I'm sorry if my idea offends, just saying - jets are tough to scale.
 

Toobuilder

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I know this is a homebuilt forum, but by the time you design and build a scaled jet, you will have years and many, many dollars invested... Why not just buy an L-39 and paint "NAVY" on the side? It will be less expensive, feature well engineered systems that would NEVER make it to a mini jet replica (pressurization, anti ice, redundant electrical, etc), and is available TODAY.

...and I just happen to know where one is.

IMG_20190915_143032816.jpg
 
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