Mike and I talked a lot about this when he was writing this article in Sport Aviation. Sorry I had to borrow so much from our older movies - and everybody else - REMEMBER! - "Area Rule for supersonic - Arnold Rule for subsonic"
Mike inspired me. I got my degree in aerospace engineering and eventually became a primary contractor for Skunk Works. His ideas are brilliant and his explanations are perfect. Thank you Mike for sharing your brilliance with us all. As a kid you were a hero, as an adult you still are. Hope heaven is treating you well.
So, the AR in AR-5, AR-6, and AR-7 will ever after stand for “Arnold Rule.” And henceforth those of us who believe in it will identify ourselves as members of the Arnold Rule True Believers Club - ARTBC. Great job on these videos, Max, and especially this one with the images of the AR-6 edited in; and the cross-fade with the little model AR-6 was superb. Again, thank you!
Hi Max. I met Arnold back in 07, when we both were invited to consult on the Icon amphibian. I appreciate your movies and I had a long conversation with Mike. We really got along and shared experiences! So sad he passed away, way too soon…
They’re very different. Burt was the opposite of a perfectionist. He liked to jam out airplanes as fast as possible with a “good enough” approach. Arnold was a perfectionist and agonized over every detail. A better comparison would be between Arnold and Cory Bird. Neither were formally educated in airplane design, both were extreme perfectionists.
I was always impressed by Mr Arnold. He passed too young. I have an RV-7 and built a RV-4 and RV-6. Van's once provided wing root to fuselage fiberglass intersection. He later went to flat sheet metal gap fairing with rubber strip, clean and simple. The fiberglass never fit well and needed modification or making from scratch. I like the clean look. Bu t the root fairings are a thing. Vans planes are flat on sides from firewall to peak of canopy on the RV-7. On transonic or super sonic aircraft AERA rule or coke bottle fuselage shape is the design goal.
Thanks for putting this and all of the other videos together Max! Mike was an amazing individual with amazing knowledge and he/It Deserves to be remembered/shared.
The Arnold Rule seems a fitting name for the phenomenon. Regarding Mike’s reluctance to promote himself, biologists are notorious for adding their latinized last names to a newly discovered slimy slug. When ya got it, flaunt it.
i bought a whole bunch of Mikes videos 20+ years ago. I did not think I could design an airplane. He changed all that. From him I learned of Hoerner, Riblett, Carmichael and others and I bought their books also. For what it is worth, all those engineering courses in fluid and aerodynamics don't help much.
"If it is real, it will still be there." This wraps up a lot, philosophically, about the permanence of ideas untethered from the physical. And it hit powerfully and beautifully, in its context about a specific idea outlasting its specific thinker in this case, and remaining true as a surviving part of him. It has had me reflecting on it for a few minutes. Thank you.
Ships hulls have been doing a similar thing for a long time with the ram ahead of a ships bow creating the same bow wave as the ship but just half the length of the frequency ahead thus cancelling out bow waves at a specific speed
Many thanks to Max for the video. Everything Mike thought about is very important. All parts of the aircraft structure influence each other causing the addition and subtraction of pressure and vacuum gradients. It's just that many designers who design this or that aircraft for a specific task sacrifice part of the low drag values for the sake of manufacturability of the design or some ease of operation of the aircraft. I think if Mike were a professional aerodynamicist, his designs for airplanes, cars, submarines and ships would be very efficient. And Mike himself would be recognized by the whole world, and not just by us (little people :) ).
Thanks Igor! it made me feel pretty smart knowing I could design some atomic submarines (with fins on their conning tower) to be faster using Arnold Rule...
Max, I too have major issues with the design of the flying V guitar. Always seemed a bit too much to me but each into his own right? On a more serious note, I want to thank you for getting these videos more publicity. I also love your commentary. Every time I sit and ponder the accomplishments of Mike Arnold I can't help but catch a grin. Because he proved that with study, determination, and effort, it could indeed be done. I have been watching and learning form Mike's video's for a long time. He is my go to source when I am working composites. I am building a composite airplane as we speak. His tutorials have provided me with peace of mind and that is something I think all composite aircraft builders are in search of. God Bless you sir.
Thanks so much, Clyde! - Now get out there and build that thing! I plan on talking about guitar design when I'm through with "Experimental German Aircraft of WWII -
Did you know that one of the designers of the Spitfire helped North American Aviation to redesign the fuselage on the P51? They reduced the width and hence cross sectional area of the fuselage, getting away from the American habit of producing huge cockpits, and introduced well designed fairings a la the Spitfire for the fuselage/wing interface. Great outcome.
A mid-mounted wing would have generated less interference drag. But, no one wants to route the load around the perimeter of the fuselage, EXCEPT in the Piper (Ted Smith) Aerostar! Ted Smith knew what he was doing.
Whether you call it inverse pressure gradient matching or the poor man's area rule, the effects are nearly the same. Just getting the air to respond with as little induced energy as possible is the goal. By shifting the canopy, fuselage, wing cross section and fillet radii, reducing the pressure gradient and air volume dynamics to move and stretch the air (an elastic medium) as little as possible can't help but make sense. I just wish I'd been taught this sort of thing in college. Thanks, Mike, and RIP. We remember you.
I remember from the documentaries,,,, most folks back here thought the Japanese were not capable of building an aircraft like the zero . But they were and did . There engineers were brilliant . They did have flaws ,,, . Thanks man .
Come on Max. Look for cassettes. Ask your friends, Mike's friends. That's the only way to keep it all. Only by distributing knowledge to people will they remember and pass it on. This means that Mike did not work in vain and sweated at night in search of truth. I sometimes think about how much useful information people have at home. All this lies and is covered with dust. But it must work for the good of the people. Thank you for continuing Mike's work, at least in this way.
I had the the tapes in my hands less than a year ago (was not set up for RU-vid at the time) while moving furniture and my girlfriend squirrels things away but would NEVER throw them away, so I know they are in this house. Looking specifically for the tapes is to frustrating, so we are slowly, methodically cleaning the entire house - ( I'm sure I'll stop the moment I find them!)
@@maxvolumeonguitar82 Your work and search (find those tapes and I'll be praying for your success my good man) is extremely important. I know it is exactly what Mike Arnold wanted. Access for all!
After the prototype DH 108 Mosquito flew, the engine nacelles were lengthened, to great effect. I wonder if this was the reason. Thank you so much for your fascinating video, and your amazing achievements. I have been building models, then piloting gliders, then PPL flying, a bit of flying twins, then hang gliding since the fifties. I've had a life long fascination for aviation, and aviation history. Now I feel like I have heard direct from a pioneer!
yes, I noticed that about the Mosquito too. I wonder if the p-38 could have benefited from Arnold Rule treatment around the booms and central nacelle (ie straight sides until the trailing edge)?
@@maxvolumeonguitar82 Max, they did do some lengthening on a P-38 test model. They extended the cockpit / fuselage aft a good distance. If you do a google search for P-38 modifications during testing you will certainly find it.
Thank you, thank you, thank you so mich, for putting up this video! What a surprise, and what a treat! I have watched those AR-5//6 video over and over on youtube, and was wishing for more. What a surprise dream come true! Great legacy for Mr.Arnold, and you; and a great resource for an aspiring aircraft engineer. Again, thank you for making this. I also appreciated the ending music. It almost made me well up.
Love that design! It’s like a foursome had a baby- Mustang, Corsair, F8F, and Spitfire (the expanding diameter wing root of the spit) I always wondered about that wingroot shape- I guess it looks beautiful for a reason! I have a question- what’s your idea of a good airfoil for high lift (at low speed) and “normalized” (don’t know the term) lift / lower drag at high speed? I noticed you have constant chord (if that’s the term) wing on that beauty- it’s what reminds me of the F8F. (I’m designing an RC airplane thats reinforced to absorb impacts, which happen far more often when you’re piloting from the ground…)
G'day, Yay Team ! This was GREAT..., Mate ; I loved every minute. It makes perfect sense - It explains a LOT... And ; my Knees are already sore From the strain of kicking my own Arse - For never having recognised the Confluence of opposing Forces to interactively Minimise Drag... Lately I've been mapping the Pressure in the Boundary-Layer around 2 different Airscrews and a pressed Sheetmetal Fan, all 3 run by Peltier-Effect powered Electric Stove-Fans. Buggar Computer-Modelling, I run the things with Incense smouldering upstream so they run in dirty Air...; wherein the constant load of Dust, Smoke, Ash, & condensing Vapour - all accumulate on the Blades In direct proportion to the ambient Barometric Pressure immediately adjacent to THAT area of the Aerofoil. As it spins for hours per day, day after day... (Endless hours of entertainment on cold Wintery Dayze) As a concurrent Experiment I also have at the moment a literal Baker's Dozen of dangling Chuck-Gliders & Scale Models ,(suitably ballasted) hanging around the Hut, as Airflow Direction-Indicators to plot which Propeller works best, and What the hell is going on with the Press-formed Sheetmetal. There are some Counterintuitively Hare-brained ways of doing things which make Lots of money For ruthless Arseholes ; and, eventually those Production-Engineers will encounter their Karmic Comeuppance (!). But, Relative Pressure Gradients are Where it's ALL at. Thanks for posting this, Excellent stuff. Arnold Rule Rulez ! Such is life, Have a good one... Stay safe. ;-p Ciao!
I'm sure glad I did!! In fact, after I finish my current series "German Experimental Aircraft of WW II" - ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-0nH9W3xYb9Q.html - I'm planning a video on meeting Mike and further adventures...
Arnolds Rule is certainly valid albeit crudely applied. There are several masters thesis' available online where they write a CFD or panel method program that edits the fuselage side while holding the wing airfoil thickness constant. The wing root fairing ends up "dished" inwards all around the wing every time. A middle-ground solution for amateurs and one that mike himself might have been close to grasping, would be to design the fuselage as an airfoil much like that on the Spitfire and Zero, but using one with known favorable pressure gradients. Then match up the horizontal wing airfoil and vertical fuselage "airfoil" in a way that their additive pressure gradients are known and can be made accurate instead of eyeballed.
My Arnold inspired single seater „XL“ has a growth a few centimeters in cabin width til the trailing edge of the wing. I expect laminar flow and some benefit at the wing root. Yes a Arnold style fairing is included. Any comments on my expectations?
This was an amazing watch, and through some pausing and thinking, my brain was able to keep up, i think. I started out in The Rutan corner of the internet and the canard interested me. Then i read about forward swept wings, and then there are combinations you want to see, and all of a sudden, the information becomes scarce. I need more of these. Great work!
I am not for certain, but I believe we are seeing the "Arnold Rule" at work in today's Formula One race cars. They use significant CFD and wind tunnel testing and appear to place their "swells" and "recesses" to no only manage downforce and cooling, but also pressure and aero stability.
This is very fascinating, I wonder if Mike spoke of if any of this could apply to a high wing aircraft? Somewhere I had read that when Cessna built a low wing Ag plane they needed to add more wing to get equal lifting capabilities to a high wing. I own a Europa mono wheel and it is a low mid wing, there was debate about if wing root fairing's would reduce drag on this aircraft. One gent did some analysis using a computer, it showed a advantage between 3 to 6 degree angle of attack with wing root fairing's
Hint: The Dewoitine 520 has a parallel fuselage above the wing and is a low decker. Not a 100% sure it fits aerodynamic check list, but worth a look. Edit: Had a look, the fuselage is parallel, but the cockpit sits behind the wing. Seeing the P 51, i get a bit confused. This looks fairly parallel to me. Incredibile, it seems most high performance propplane designer think it doesn't matter enough in curves, when the AR-6 placed records at Reno. At least till 2014. Couldn't find more about its placements after 2014.
How would a sailplane look if it were designed to the Arnold Rule? The lack of an engine changes where you have to put the cockpit with all the pilot weight.
I would try to make sure the canopy peak and the point of maximum thickness on the airfoil do not line up and the fuselage sides stay straight until the trailing edge is reached...
I promise you that if I ever design a low-wing aircraft, I'll be using the Inverse-Pressure-Gradient Matching Rule. ( I'm eradicating all the name-memorizing from things, in my work, so going the opposite-way, & calling it The Arnold Rule just forces students to do more memorizing. Having things challed what they ARE, reduces memorization & increases understanding, in kids, & that's whom we're supposed to be rigging the world *for*, right? : ) Thank you VERY much for making this video. & for your explanations, including the way it's different from the supersonic Area Rule. Salut, Namaste, Kaizen, & Gratitude, eh? _ /\ _
Interesting discussion. Although it's mistaken about climbing. Cl is no larger in a steady-state climb than in level flight, it's actually a bit smaller because thrust is angled a bit up. (This is obvious if you take it to its logical conclusion and climb straight up -- in that case lift is zero.)
@@danielcockerspaniel Obviously, if you want best rate of climb, you should climb at max L/D (At max speed, you can't climb at all, by definition.) But that's just a speed dependence; at a _given_ speed, Cl (largely) doesn't change if you're climbing, descending, or in level flight.
@@patrikj you need to go back to your aircraft performance text books. Best rate of climb for a propeller airplane occurs at min power required, which is not max l/d
@@danielcockerspaniel I stand corrected. Doesn't change the point about Cl in steady state flight not depending on whether your climbing or not, though. Now that I'm thinking about it, maybe they meant "Cl at climb speed" instead of "Cl when climbing" in which case they'd have a true, if opaquely stated, point.
well there's no real canopy on a high wing (usually) and they also (usually) have big ugly struts going out to the wings. But keep the fuselage sides parallel until you hit the trailing edge! - (this from a guy who never designed an airplane...)
but Bruce Carmichael told me (as we rode on the little trolley by a C-5 Galaxy at Oshkosh) that they couldn't get the C-5 off the ground until they put that fancy wing root fairing on it - so I would think wing root fairings are important either way
also the landing gear has to be dealt with - if they're wing mounted, they will have to be longer to reach the ground (with longer gaps in the wings if retractable). If they're fuselage mounted and it's a small plane, the wheels are probably to far inboard to be ideal (as in perfect-) and if a retractable tail dragger, it can be bulky (see Focke-Wulf Fw 159). Hope I'm right about all that!
Simple: take the derivative of the shape in the streamline direction, and keep taking those derivatives until you don't feel like it any more. Every discontinuity is lost energy, and, therefore, smooth over those discontinuities. Now integrate back to where you started. Everything else is snake-oil.
Mike never made any plans for sale because of liability, but have a look at the Ar-7; ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-G_diBdT5_gM.html or the Arnold company videos; www.youtube.com/@thearnoldcompany2958 ...
@@maxvolumeonguitar82 If the guy made marvels with paper and pen, can't imagine him using a professional CAD program, joining, filleting, substracting parametric shapes and testing with a xflow or openFOAM apps.
@@jorbedo CAD was in a primitive state back then - Mike used to comment about obviously CAD automotive designs (not in a good way) - Would Michelangelo's David look any better if it was designed by a computer? - not yet!
@JorBedoSan CAD was in a primitive state back then - Mike used to comment about obviously CAD automotive designs (not in a good way) - Would Michelangelo's David look any better if it was designed by a computer? - not yet!
Glad you asked, Brandon! - 'Arnold Pressure Gradient' sounds like a single gradient whereas in Arnold Rule two different gradients are working against/with each other to straighten out flow through the air. Remember, we're trying to make this simple and easy to recall. Area Rule was there first so it's easy to remember; 'Area Rule for Supersonic, Arnold Rule for Subsonic'. Thanks for giving me an opportunity to say that, Brandon!
