Practical Aerodynamics for Model Airplanes

Practical Aerodynamics for Model Airplanes
In this video I will cover practical aerodynamics for model airplanes. Easy to use and understand rules of thumb for aviation aerodynamics that will make you a better RC airplane and model aircraft pilot and help avoid a crash some day.
Aerodynamics for airplanes, full scale or model, can be complex. But it is not hard or complex to break these items down to understandable modules. See chapter below for where you may wish to view a particular subject.
Areas that are covered include airplane controls, flaps, wing incidence, motor right and down thrust, wings and the creation of lift, stalls and angle of attack, center of gravity, warps, wing dihedral, flutter, trim, advantages of a high vs. a low wing airplane, elevons and computer assist such as AS3x (Automatic Stabilization 3 Axis).
Here is a link to my KZbin Channel:
/ timmckay56
Many thanks in advance for a post of this video on Facebook, it truly helps the channel a lot!
Regards,
Tim
Pronto airplane:
• Build the Pronto RC Ai...
Square Flyer:
• Square Foam RC Plane -...
E-flite Pitts RTF:
• E-flite Pitts S-1S RTF
AS3X:
• Spektrum AS3X for Newb...
Mini Lazy Bee:
• Build a Foam Board Min...
Foam board F-22:
• F-22 Foam Board RC Air...
Flight trim:
• How to Flight Trim an ...
Chapters:
00:00 - Intro
01:21 - Airplane controls
02:00 - Flaps
03:30 - Wing incidence
04:39 - Right and down thrust
06:27 - Wings and lift
10:04 - Stalls and angle of attack
13:57 - Center of gravity
18:12 - Warps
21:00 - Wing dihedral
23:13 - Flutter
24:40 - Flight trim
26:00 - High vs. low wing
27:30 - Elevons
28:42 - AS3X
30:15 - Conclusion

[@oddshot60]

Thank you. I want you to know how much I appreciate you making these vids AND taking the time to address my questions.

[@TimMcKay56]

TD: Thanks for much for your kind words! Tim

[@thewayfaringanarchists8157]

I live in a Military Operations Area so i often get extremely up close airshows form our local EA-18s that have kept me glued to the topic of aviation my whole life. I recently started building foam board airplanes with my son, its been very rewarding and your videos have been a huge resource . Thank you

[@TimMcKay56]

Sounds good, thanks for checking in! Tim

[@4thGloryMonday]

ANOTHER ONE OUT OF THE PARK, THANKS TIM!!!

[@TimMcKay56]

Many thanks! Tim

[@emorywright7607]

Great info, amazing how most modelers don’t know the basics of aerodynamics. 👍🏽

[@TimMcKay56]

Thanks for checking in! Tim

[@KGReef]

My son and I have started building foam planes recently, thanks to some inspiration from your builds. This video is full of super helpful information we can use to help us be much more successful with our designs! Thank you!

[@TimMcKay56]

Awesome, thank you! Tim

[@aldeen19]

Very essential information.. Thanks a lot Mr. McKay 🙏

[@TimMcKay56]

Thanks for checking in! Tim

[@davisgloff]

This is great information for everyone, and a good refresher for experienced flyers. Thank you!

[@TimMcKay56]

Davis: Glad it was helpful! Tim

[@stevedessert5663]

Great video.

[@TimMcKay56]

Thanks! Tim

[@oddshot60]

I hope you don't mind ... I have questions. 1. Longitudinal axis = LA a. Is the LA a line extending from the horizontal stabilizer through ... what? the center of the motor? What if the motors are higher/lower then the horizontal stabilizer, or the horizontal stab is higher/lower then the center of the motor? b. When establishing the LA ... what role, if any, does down thrust play? If the motor has 5 degree of downthrust ... where does the LA intersect the centerline of the motor? c. What if the "top of the aircraft" is not parallel to the LA? Is the 2 degree angle of wing incidence relative to the "top of the fuselage ... or is the wing incidence and relative to the longitudinal axis? d. What about bi-planes? Do both wings require an AOI?

[@TimMcKay56]

LA is from the nose to the tail, is the axis the airplane rotates around. LA does not have any interface with motor down thrust, just a measurement from the nose to the tail. No interplay with wing incidence either. For biplanes, usually the lower wing is zero incidence, upper wing positive a degree or two. Tim

[@ronbell8967]

As always Tim, a great summary of the key aspects of multiple complex topics. Thanks.

[@TimMcKay56]

Ron: Great to hear from you, hope all well with your retirement! Tim

[@dutchloveRC]

great video friend, lots of good info

[@TimMcKay56]

Glad you enjoyed it! Tim

[@me262a1]

Great video! I needed this 3 years ago. LOL

[@TimMcKay56]

Glad it was helpful! Tim

[@JeffinLowerAlabama]

Tim fantastic information, i was lucky to have a great builder and flyer of full and models Rick to teach me these aerodynamic principles, can hear Rick say keep the the plane axle so it will fly. Jeff in LA USA

[@TimMcKay56]

Jeff: All good, thanks for checking in! Tim

[@markpatterson4917]

Like watching your advice video's. I've been flying over 20yrs all your advice is sound. The only thing I'd add is that you need to be aware that a lot of plans/manufacturers place the centre of gravity to far back. My Dynam Spitfire was prime example the C of G from the instructions was great for taking off (not nosing over) but once in sky it was pitchy and barely flyable, luckily farmer had just cut the hay so aimed at a nice loose heap and it was ok. If a novice its always a good idea for an experienced modeller to check it out first before flying you plane. It's always cheaper and quicker to learn by joining a club in the long run. Keep it up Tim great video

[@TimMcKay56]

Mark: Thanks much for checking in, agree completely with your point on an aft CG. 😀 Tim

[@ShinninjaMartian]

Im in 10th grade and am interested a lot in aerodynamics. I even study it during my slack time. The night i studied the aerodynamics of a shuttlecock till 4am was the time when i realised that this could be my passion in life . So here im. Thanks a lot for the vids❤

[@TimMcKay56]

No worries, thanks for checking in! Tim

[@notpoliticallycorrect]

Super video! I learned so much!

[@TimMcKay56]

👍🏻😊 Tim

[@Wild_Bill]

Thank you, sir. Very well taught. Wish I could fly with you. Respectfully.

[@TimMcKay56]

WC: Thanks for checking in! Tim

[@miquelsalvatejedor3123]

Thank you. Great content.

[@TimMcKay56]

Glad you enjoyed it! Tim

[@Mr.Laidukas]

Thank you for this great video, you have a new subscriber from Lithuania.

[@TimMcKay56]

Wonderful news, we always enjoy our trips to Lithuania! Tim

[@eeyore74flightfishing]

Awesome video!!! Your videos always want to make me stop what I am doing, and just start building 😂 I love foam board planes and the verity of modifications you can make!!

[@TimMcKay56]

Eeyore: You can do it! Tim

[@grigiomacgufo4525]

Thank Tim! I like a lot all your videos. Very usefull for a newsbie as i'm am !

[@TimMcKay56]

Grigio: Glad you like them! Tim

[@davidlourensz4822]

Hi Tim, it's really good to see someone with good knowledge and professional aviation experience put these videos together. Makes me want to pay attention. I used to fly light aircraft and studied what you were talking about in this video but always good to hear it again from a professional. Thank you kindly and will be watching as they come out. Have subscribed. (Perth, Australia)

[@TimMcKay56]

David: Thanks for your kind remarks, and I’m looking forward to my Sydney visit in Dec! Tim

[@rlbutterfield]

Great information. Thanks for sharing. 👍🏻

[@TimMcKay56]

Glad it was helpful! Tim

[@roadstercm6]

Great job on your videos.

[@TimMcKay56]

Thanks! Tim

[@planker]

Good stuff. Thats a lot to unpack, yet knowing the CG is the Bullseye. Guillows kts offer build/flight notes, and Plans from Cleveland have lots of foot notes. My Dad would say read the plans twice before touching a knife. Foam Jobs in a box give us little time learning Aerodynamics and that usually end in loss. I have worked on the F-4, I could Never get my head around the CG locations, Its more of a rocket.

[@TimMcKay56]

Planker: Great inputs, thanks! Tim

[@martinj9251]

Another fantastic tutorial, Thank you from England 🇬🇧

[@TimMcKay56]

Martin: Thanks for watching! Tim

[@davidquerry8869]

Fun video Tim.

[@TimMcKay56]

David: Thanks! Tim

[@i9mm2]

Thank you great video

[@TimMcKay56]

Many thanks! Tim

[@tomcarroll6744]

Good stuff, thanks.

[@TimMcKay56]

😊😳 Tim

[@gerryherman7420]

Thanks!

[@TimMcKay56]

👍🏻 Tim

[@TimMcKay56]

Gerry: Your Super Thanks is awesome! Regards, Tim

[@Razor-gx2dq]

13:45 I've experienced this before, I have a 400mm P-51 and sometimes when I fly in the wind I can be at full throttle and i can hover the aircraft or sometimes the wind is strong enough to push it back at full throttle.

[@TimMcKay56]

Good observation! Tim

[@dustineputtaert5792]

Hi I have a guillows spitfire 504 do you know if it could be made to be RC and if so what motor, servos and battery would you recommend on a tight budget

[@TimMcKay56]

Dustine: That’s a 17” wingspan, quite smaller model. The Spektrum RC gear is likely the best fit, but I am not sure on this smaller size model. Do take a look at my video on larger Guillows Spitfire conversion. Tim

[@dougj8186]

Nice presentation, easy to follow explanations. I have a question. Do you know what value there is in reducing drag in terms of performance, for example root wing fairings, for models. I think sub-250 gram is going to be the new thing (it is for me anyway) with Remote ID. I'm pretty certain it will end park flying for everything else.

[@TimMcKay56]

Doug: Thanks for this input. Full scale airplanes seek to reduce drag to fly a bit faster (Cessna 172) or meet a range target (B-777). Our models don’t care about range and are so overpowered speed is not an issue. So anything to reduce drag in a model is for appearance. And I really am not worried about Remote ID. If industry can do AS3X, they can figure out Remote ID. Tim

[@dougj8186]

@@TimMcKay56 Thanks Tim. Remote ID is not a technical challenge, I was talking about the practical effect when the public gets wise to the app and anyone with a cell phone can ID an aircraft and turn that person in for [take your pick]. Some people get annoyed at anything flying near them and all it takes is one complaint. Also, I don't know if you fly RC in the wild but it's OK until you ask. Then someone has to make a decision, take responsibility, ask a boss, etc. So I'm serious about sub-250 gram. I think a decent size plane is possible but 250 grams is not much to work with, hence the drag question. I've now made 60" 3D printed wings covered with balsa that are as light and nearly as strong as foam cores/balsa for a twist wing plane I designed and conventional with ailerons. I'm looking at scaling that technique down. I've also designed 2 meter 3D printed sailplane wings covered with Dollar Tree sheet foam but it takes an airfoil thick enough to account for the 4.5mm of foam x2. The melting point of the foam is close to covering film so it's difficult. Paint is easier, not as nice but the beauty is the total cost is about $5 for a 2 meter wing. That's going on the back burner until RID is sorted out. Lemmon now has bricks with conventional servos similar to HH UMX types for $37. There are tiny but I'm starting there.

[@TimMcKay56]

@@dougj8186 Great info! Do keep in touch, sounds like you are on the right track, good luck! Tim

[@dougj8186]

@@TimMcKay56 Thanks again Tim. My goal is a sub-250g plane that doesn't seem like a toy.

[@TimMcKay56]

@@dougj8186 Sounds like a great plan, good luck! Tim

[@Yo-mamashouse]

I've been watching a lot of your videos and can't find anything on how you hinge the guillows models controls.....you should show how with tissue paper covering and shrink covering...thanks for your informative videos.

[@TimMcKay56]

Mr. R: I think I mention it in the videos, but for the Guillow models I simply use clear Scotch adhesive tape. Works like a champ, lightweight and invisible. Tim

[@txkflier]

When a control surface flutters, it's usually because the control horn is too short or the linkage is too flexible. If you need more throw, use a longer servo arm instead of shortening the control horn. Make sure the servo output is rotating about 40 degrees either side of center in high rates. When you turn down the travel in your transmitter, you decrease its resolution and accuracy. Also, if your trims aren't centered after you get your plane trimmed to fly straight and level, adjust the linkages on your control surfaces so that your plane will fly straight with the trims centered. When your trims aren't centered, neither are your servos. Leaving the servos offset from center will cause the control throw to be greater in one direction than the other. One other thing. On flat-bottomed wings, the ailerons need 1-1/2 to twice as much travel up than down to prevent adverse yaw. If the servo(s) and control horns are on the bottom of the wing, you can install the servo arms one tooth toward the leading edge when the servos are centered. Or, you can install the control horns about 1/8 to 1/4" back from the hinge. In either case, the linkages will need to be a little longer so that the ailerons are centered at neutral. When you use the differential function in your transmitter, it decreases the amount of servo travel in the downward direction which as I said earlier, decreases the resolution and accuracy of your radio. It also requires the use of two channels, one for each aileron servo.

[@TimMcKay56]

Yup, I remember well the old day of RC, without even servo reversing. Installations really had to be planned out, and using the full control horn, horn at 90 degrees, etc. all super important. Tim

[@txkflier]

@@TimMcKay56 Yeah, years ago, we’d reverse a servo by swapping the motor wires and the wires on the ends of the feedback pot. We had to clean and lubricate the pots occasionally, so swapping the wires wasn’t a big deal to us. We also had to adjust the pot to center the servo. Now everything is done in the transmitter and we replace a servo instead of working on it. Computer radios have made everyone lazy. Instead of learning how to properly set up control linkages, they attempt to cover their mistakes by tweaking the settings in their transmitter.

[@gordonmckay4523]

@@txkflier Good points, and I remember those days well! Tim

[@oddshot60]

More Questions: 1. Wing Dihedral: Does greater dihedral create more drag and then a slower model, and is the reverse true as well? 2. AS3X. Is that function just part of the receiver ... or it in the transmitter as well? Can it be added somehow to an existing a/c? By the way ... love your vids.

[@TimMcKay56]

Dihedral does not add drag to an airplane, just there for roll stability. AS3X is built into that receiver, not part of the transmitter. See my video on AS3X, I go over all the details. Tim

[@StephanAhonen]

Dihedral means the angle of lift is away from vertical, which means you need more lift for level flight, which means you need more angle of attack, which means you create more drag.

[@gordonmckay4523]

@@StephanAhonen Well, OK. But the amount of induced (lift) drag from dihedral is very small, never included in calculations. Tim

[@txkflier]

An airplane that has a rudder, but no ailerons must have dihedral in order to turn. When the rudder yaws the airplane, the wing is turned at an angle to the relative wind which increases the lift on the advancing half of the wing while decreasing the lift on the other half. This will make the plane roll in the same direction that the rudder was deflected. AS3X is a feature in some Spektrum receivers. It can be turned on or off from your transmitter and you can also adjust the AS3X gyro gains from your transmitter, if desired.

[@gordonmckay4523]

@@txkflier Depends on the airplane. I have several zero dihedral planes with rudder and they turn. Bit of a skid, but they get around in the sky. Tim

[@oddshot60]

And more ... You didn't discuss drag. Does drag impact model ac? What on a model ac creates drag? Should modelers be aware of things that create drag and try to eliminate it? Jets are round, Piper Cubs are square. Do round ac have less drag then square ac? Are round ac more efficient, more stable and faster than square ac?

[@TimMcKay56]

Drag is a long subject, best to Google Airplane drag. There are two types of draft, parasite and induced. Parasite is the aircraft structure, induced is from lift. Model airplanes have drag just like full scale ones. Tim

[@honkhonk8009]

5:29 That is so true. I was grinding war thunder and tried out simulation mode awhile ago. I tried out the B36 and P47. My plane kept on rotating when I took off, and less so when I was in the air. I couldn't even trim my ailerons to compensate cus i didn't know the keybinds💀💀💀

[@TimMcKay56]

All good! 🙀😊😳 Tim

[@user-go3bl3iy5b]

Tim: I built a flight test mini cub and installed a trunigy 2815 motor is that a big enough motor to fly this model. Thanks Don

[@TimMcKay56]

Don: Should be, looks like a peppy motor. Tim

[@barrywinslow9798]

Tim, what about a pusher design on down thrust etc.....thanks.

[@TimMcKay56]

Will add to my list! Tim

[@barrywinslow9798]

@@TimMcKay56 Thanks Sir.....hoping to start my scratch original next month.

[@TimMcKay56]

@@barrywinslow9798 Good luck! Tim

[@barrywinslow9798]

@@TimMcKay56 Thanks my friend.