Why do foamies Deltas are so poorly efficient? - Page 4 - RC Groups
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Apr 19, 2018, 08:01 PM
Build straight - Fly twisty
Whiskers's Avatar
Those of us who, when very young, fiddled around with model planes should understand that we received an education that many others missed.
What seems instinctive to us is not so to them because our knowledge only had to replace our pure ignorance, whereas in later life ones ignorance is more complex and overlayed with misconceptions.
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Apr 19, 2018, 08:14 PM
i can't learn fast enough
Oh soooooooooooo true. Best answer i ahve seen yet.
Thanks Wiskers
Apr 19, 2018, 10:10 PM
Registered User
pure ignorance is best... therefore I win.

Seriously I believe only what I see, or at least I will entertain ideas until I show them wrong which is fairly often.

Not really related but I was a kid and they tried to say wings work by bernoulli principle, my instinct said NOT. And much later I read a website that was over my head by a fellow poly grad that proved bernoulli had nothing to do with how wings fly, in fact the pressure above the wing and at the surface was higher. Jeeze tons of weird airfoils prove that idea wrong. Someone will say models are different I say .... your post contains the following objectional words...woops.
Apr 19, 2018, 10:45 PM
Build straight - Fly twisty
Whiskers's Avatar
Bernoulli's principle is a real thing. Many devices use the principal and would not function otherwise.
Wings also use it but obviously It is not the only force involved. As well as the direct effect it has on wings it also plays a part in redirecting the airflow and it is this that is the main contributor to lift.
Apr 19, 2018, 10:59 PM
flyin' fool
goldguy's Avatar
Originally Posted by goldguy
Some of you guys are overthinking this hobby. I was chucking around model gliders successfully seventy years ago when I was just five years old. *** I just followed the instructions that came on the package. The rules haven't changed since.
I would like to re-quality that post..............................
*** I just followed the illustrations (part A goes into part B). Heck, I didn't even know how to read.

Now we get perfect downloadable free plans and build threads to boot, and some still get it totally wrong. If you expect to have the finished product fly properly, then built it as designed.

But no! All I hear is it flies like crap and is total junk.
Last edited by goldguy; Apr 20, 2018 at 12:10 AM.
Apr 19, 2018, 11:12 PM
flyin' fool
goldguy's Avatar
That poly grad student may have a degree, but that doesn't mean he's smart. A posted theory is not fact and I sure his finding were just that. I don't believe his conclusions either. I side with Whiskers, because there's lots of info to 'prove' the opposite.

Besides, I've seen with my own eyes and felt with my own body what it takes to fly. I used to sky dive and I could actually fly forwards at a 1:1 ratio, one down, one forward, at 180 mph. I could actually feel Bernolli working on my top side, but also the dense air I was 'skipping over like a stone on water' on the bottom side. The air below was definitely denser than that on top. FACT, not a theory.
Last edited by goldguy; Apr 20, 2018 at 08:37 AM.
Apr 20, 2018, 03:27 AM
Registered User
Extreme Sports's Avatar
As Ray has pointed out, the OP has moved his curiosity to the Modelling Science forum. So please put your anti-intellectual pitchforks away

I find these last few posts both interesting and deeply sad.

Folks, this hobby is made up of so many facets - buying, flying, the full spectrum of kit and scratch building, phenomenal scale modelling, science, electronics and automation, multi-rotors, helping others learn, etc etc. Some are interested in just one aspect, while others find all of it fascinating. The OP clearly has a desire to understand WHY his planes fly or don't fly, and to understand the science behind what he is doing. If he could I suspect he would want to put it all into a mathematical formula. To some that may seem like over-analysis and going around in circles, but that is how he chooses to enjoy the hobby and grow his knowledge. And to be honest, that closely mirrors the way I learn.

That may not be the way some of your learned, but that does not give any of you the right to pour poorly disguised scorn on those whose learning style differs from yours. Any thread may go in a direction that no longer interest you. If someone pursues a line of inquiry that, in your opinion, is 'over-analysis' but others are still interested in contributing, then please rather just move on and make your positive contributions to threads that do still interest you.

Aerodynamics is both theoretical and empirical, and the hobby would be so much poorer if either was somehow considered unacceptable. Likewise, science is a process of developing theories and then proving or disproving them. Often this involves running up blind alleys and enduring the scorn of those who hold a different view, or simply think they know better. It can be a messy process, but bit by bit the frontier of human knowledge moves forward. Ironically, science advances fastest when it brings together the views of BOTH those who progress by experimenting and those who progress by analysis. Neither is better than the other and neither party is 'smarter' than the other. They are just different styles of inquiry and both are equally important. And both can learn from each other.

Sadly, the last few posts remind me of a time when frenzied pitchfork-bearing crowds burned 'heretics' at the stake simply because they dared to ask questions that made the 'in crowd' uncomfortable, or had ideas that challenged the conventional wisdom. Simple, yet totally outrageous things, such as the earth revolving around the sun, or that the powers of rulers were perhaps not absolute.

I think some personal reflection is called for.
Last edited by Extreme Sports; Apr 20, 2018 at 03:39 AM.
Apr 20, 2018, 07:57 AM
Build straight - Fly twisty
Whiskers's Avatar
I didn't think any of the above posts would justify such flames.
Maybe some of us are more used to vigorous debate and don't see the statement of an opposing view as a personal attack.
If you detected, "poorly disguised scorn" in anything I wrote I assure you that no such thing was intended.
One of the problems of written communication I guess.
Sometimes I think I should have a standard sign off that says, "If I have written something that can be taken two ways, and one of those ways makes you angry and upset; I meant the other way."
Apr 20, 2018, 08:46 AM
flyin' fool
goldguy's Avatar

Yes .............. a response that's a little over the top, as in 'extreme'. Nobody is try to hurt anyone's feelings here, except you.

Last edited by goldguy; Apr 20, 2018 at 08:58 AM.
Apr 20, 2018, 08:55 AM
An itch?. Scratch build.
eflightray's Avatar
At least in the Modelling Science forum there are enough 'experts' trying to convince each other that 'they' are right.

e.g. this thread -- Bernoulli's Principle Always?

it's enough to make anyone realize that you don't tell your model plane anything about aerodynamics, and they will continue to fly just fine.

Ignorance + practical experience = usually success.


WARNING: Should you try to read the linked thread, you are warned it can lead to brain damage.
Unless you use a padded wall to head bang.
Last edited by eflightray; Apr 20, 2018 at 08:59 AM. Reason: Added the warning
Apr 20, 2018, 09:16 AM
flyin' fool
goldguy's Avatar
By the way, the grad student I was referring to was the one the other grad student was referring to as a 'fellow grad student' regarding his findings on Bernoulli.

Part A into part B .............................
Last edited by goldguy; Apr 20, 2018 at 09:48 AM.
Apr 20, 2018, 11:05 AM
Registered User
Wow, I don't think anyone was trying to "scorn" the OP in any way... someone has a huge imagination. I actually love it when people disagree with me, I like to think I killed my ego years ago when I realized how short life is, there's no time for it.

I find most posters on RC groups also enjoy theoretical discussions, and I particularly enjoy it when people back their ideas up with real life experience.

I am a geek and I watch my mind, I try to never get nasty or "I'm right and you're wrong" about things... I see very little of that in this thread, or maybe I'm good at ignoring it.

As an aside, the bernoulli folks have to explain to me things like the nutball and all the other good flying planes with nothing but a flat plate for wings, often not even a sanded leading edge...just my thinking and could be wrong. Not arguing it's not a "real thing", just it has nothing to do with how wings fly... I don't expect everyone to agree, since that is what's in the text books and most people take them as fact - end of story. That's how ideas continue through time, right or wrong.

Again, I find this stuff interesting, not to massage my ego or get emotional.

Did I write "fellow grad student"? Sometimes I post late at night and screw up, I am a cal poly grad and my roomates were aero engineering students, I was a grad student once but now I am permanently an official old fart.
Last edited by rotagen; Apr 20, 2018 at 11:12 AM.
Apr 20, 2018, 11:15 AM
“There’s no place like Foam”
gpw's Avatar
Technically we’re entitled to our own opinions ,even if we're wrong … Lets all agree to disagree, and yet stay flying buddies …

Actually we rather like deltas , having flown practically all kinds of wings on planes …. each has it’s advantages and disadvantages … No one wing does everything …. unless you’re not doing much …. hahahaha
Latest blog entry: Lost plans
Apr 20, 2018, 06:41 PM
Sopwith Camel's Cousin
One thought is that there a different kinds of forces that will get a wing to provide lift.
Some wings might use a combination of forces to get their lift
With my flat foamie (well it was flat until a few crashes bent a curve into it ), I need to angle the wing up a bit so it can deflect air downwards to get its lift.
There are Magnus effect planes that have a spinning wing to slow down the air movement underneath the wing and speed up the air movement above the wing to produce a pressure differential for lift.
I have also read of planes that have props to blow air on top of the wing (but not the bottom) to speed up the air above that wing to produce a pressure differential for lift (channel wing by Custer).
So for certain designs, just one of these forces may be enough to provide the needed lift.

p.s. I like wings. I learned to fly on my own and my first plane was a tailless 4 channel.
Last edited by flying-llama; Apr 20, 2018 at 06:57 PM.
Apr 20, 2018, 06:59 PM
Registered User
Originally Posted by BHOFM
I have been trying to tell people here that for years!

Until some one comes up with a better flux capacitor the
rules won't change!
The op is wanting long flight times for most use of his availible batteries. Flies a delta finds it so much fun but that fun comes at a cost... His previous experience lane's r easy slow yers

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