I am planning my second plane, which will eventually be an aerial photo/video platform. I'm still finishing my trainer (SPAD) so I have plenty of time to grasp all of this and it should be a good exercise for my balsa venture.

I’m gradually getting the concepts of wing loading and lift. I barely get the variable of Lift Coefficient and the Reynolds Number still escapes me. Did I mention I am a math-neanderthal? So I usually drop into a drooling coma on anything past basic algebra.

My question is what are the best techniques to decrease wing loading to get stable, slow flight characteristics (say 12-17oz) — outside of weight reduction. It seems to me from the reading I've done more weight equals higher wing loading, so do you just scale up the wing proportionately, more chord/span, bigger flaps?

I like the layout of something like a Balsa usa stick 40 but larger format, upwards of 75-80" span. I haven't seen something like that in my searches as a kit.

Anyhoo, thanks in advance for any help.

I used a Stick 40 for my trainer and built a Sig LT40 for my son. I think a Sig Kadet SR or a Sr Telemaster would do what you want. I also built a SPAD deb for my father in law to learn with. It really flew good but it lands faster than the balsa trainers mentioned... Higher wing loading.

First, How long have you been doing this?

Second, Do not get too wrapped up into the wing loading thing, since everything that you have been told concerning this is probably in error. I have seen plenty of model airplanes that everyone said was too heavy for the amount of square inches of wing, fly great. Wing volume comes into play and blows your thinking away.

Airfoil shape makes a huge difference as well. Take the beautiful scale (sic) P-51 Mustang you saw last weekend at the field for example. Chances are that the airfoil was nowhere close to the scale laminar flow airfoil that the '51 used, but was probably either a semi-symmetrical or a modified flat bottom airfoil, in order to get the plane to fly with some degree of success.

Reynolds numbers don't really come into play until you get into the size of most 1/4 or 1/3rd scale planes. The wing volume is just not great enough for the factor to make much difference. Compute the difference in a wing with 500 square inches to a wing with 600 square inches. Consider both these wings to have a max cross section of .75" and a mean average chord of 8" The reynolds number does not change significantly does it? Now compare the difference in a wing with 2200 square inches and a wing with 2300 square inches. Consider these wings to have a max cross section of 2.5", and a MAC of 17". Same 100 square inch increase, but a big difference in Reynolds number.

Time will teach you much more than anything else. Just keep on plugging away, and if you wish try some things on a junk plane. Who knows, you might just luck into the perfect model airplane.

Bill, AMA 4720
WACO Brotherhood #1

The bottom line is that there are only two ways to decrease wing loading.

1. Decrease weight.

2. Increase wing area.

As stickbuilder noted some wings fly better than others based on what you want your aricraft to do.


Darren

Thanks for the input guys. I've not been building very long as far as planes. I actually learned 20 years ago on a ARF balsa plane which came to a demise on my sixth flight. I later learned the guy who was instructing me probably wasn't qualified, but there was no formal training regimen at my rural club then.

Anyhoo, I moved on to the first Dura-Plane model they produced but I couldn't find anyone who was willing to instruct me on a consistent basis and sold the plane after only two days of flying.

I've been racing RC cars for about two years now and got the itch to fly again. So I studied up and liked the sound of SPAD for the durability and ease of repair sake, okay the wallet chimed in as well. I figure I can get the crashing out of my system with that and take my time planning my first balsa build.

That being said, I like to research so I got most of my info from NASA and Aerospaceweb.org as well as a post on wing loading/Reynolds Number here. I kept running into the reynolds number comment and coefficient stuff and it baffled me. So I thought to play it safe and ask.

Rvator: I considered the Kadet for this project, but a standard fuselage leads to more fabricating than I want to do for AP, but I'd love to build one some day a leisurely floater. The Kadet Sr. ARF is one beautiful plane.

Stickbuilder: thanks for the info regarding reynolds and airfoils. That means less math for me! Well, till I decide to build a 1/4 scale!

Look up the Jerrys Big Boy and the Ryans Rebel. Wing spans are exactly what you are looking for and they will lift a ton. They are like large scale versions of the stick. The Big Boy has a larger chord. Another good one to look at is the 100" LIftmeister from Cedar Hobbies. Any large Telemaster will do the trick as well. The 94" version is a heavy lifting machine!! Telemasters even have a lifting horizontal stab.

Build a big Telemaster, They're perfect for what you want.. Aside from this , you haven't even started flying yet. with no disrespect here, you have got a clue on how all this works. Building a spad as a trainer? I wouldn't recommend that route at all and then your second plane full of video equipment. Sorry but this has disaster written all over it. I'm not even going to debate math with you. You may know wing loading in theory but nada with first hand experience.

Weve been talking of a telemaster. Wingloading will come out fine as long as you build it by the book along with recommended engine and the whole enchilada. But if you change things around by installing a larger engine and camera equipment and extra large fuel tank etc, it's going to get higher. Even with this, the plane could still fly like a balloon or drop like a brick. I have seen a few guys in my day obsessed with the numbers. They come out to the field and spend all day screwing around with the plane for know reasonother than the numbers in their heads are not the same onthe plane and never willbe but you can't convince them of this.

I suggest you take a normal training route and learn the right way or your ego will be your own worst nightmare on this whole hobby.

Thanks to all for the plane suggestions and training advice. I am absorbing it all, (I think.)

I'm just idea searching regarding the "second plane" at this point. I don't suspect I'll even start another build till I've been soloing for a bit (well other than spares for the trainer). I should have expounded that I wanted my second plane to be capable of being an AP test-bed. It doesn't mean I would throw camera equipment on it as soon as the glue dries, but I want that future tinkering capability. Assuming it survives that long!

Another reason for the SPAD direction is that the club I am considering has a fair amount of spaders there and they have several instructors I still need to pay the field a visit and go to a club meeting. I've talked with several local flyers at the shops and two other clubs I ruled out, and I feel the SPAD is a fine route for me.

happypappy: Regarding my "stick" comment, I was referring to stick/rail type planes like the Balsa USA Stick 40. Though I guess I never thought about those aerobatic Big Boy or Ultra Stick as being a viable option. I suspect the giant Telemaster and Liftmeister would be a bit larger than I would want to take on at the second plane point. [X(]