RealFlight aerodynamics

wahubna15

New member
I am working on a UAV design project at the moment and am using RealFlight's editing capabilities to compare design aspects like aspect ratio, wing sweep, area, etc.

I had previously used this method to design a glider and my glider ended up matching the characteristics predicted by RealFlight very closely. Thus I have confidence in the abilities of RealFlight, however, I would like to have a bit more technical comparison rather than just "yeah it is pretty good".

Has anyone else compared the effects of making an edit like wing aspect ratio in RealFlight to real-world?
 
There have been a few cases where people developed a concept model in Real Flight to predict performance of a real world build. When the user has the knowledge to configure physics properly in Real Flight, the real world performance is very close.
 
We've used the "predictive modeling" capabilities of Realflight many times.

Note however that since the 6.x releases, which include "center of pressure modification" in the editor, the way the airfoil effect of the fuselage is modeled has changed a bit.

This results in say, an adverse yaw when the real plane will not exhibit the same.

The Folkerts SK3 is a recent example of this.

To view the "problem" go into the editor and set the "center of pressure" modifications for both top and bottom, and sides on the fuselage back to their defaults.

Now fly the plane and you'll notice it will knife-edge all day long without ANY corrective inputs. The figures I punched in, make the modeled plane fly like a real world model.

As with ANY simulation the predictive capabilites are only as good as your real world testing and adjustment.

You absolutely MUST check the sim and the different parameters against a known real world plane, so you learn what needs tweeking on a predictive model, before you trust the sim to give you accurate results for the latter.


For instance... to predictively model the orbits of satellites, I had to use a gravitiational "geode" model of the earth... to get the latter, you have to send up a satellite to collect the model data! There is no middle ground, so to speak...
 
opjose, is there any way to adjust a plane in the RF editor so it has realistic taxi/take-off characteristics? I often want to practice take-offs with planes that normally have bad ground handling characteristics (e.g. a Cub) but they all seem to take off in a perfectly straight bee-line in RF.
 
Yeah Flexible did a good job making that plane harder to fly.

You can:

- Make the tail sit lower to make the plane more yaw prone.
- Give less authority to the rudder
- Increase "P" factor type entries and torque transfer
- Increase wing stall factors
- Increase flying weight.
- Adjust C.G., center of pressure...

etc..

All of this effectively "de-tunes" the model to give you more real world characteristics, instead of idealized behaviour.
 
Open this file in the editor, to get some ideas.
https://forums.realflight.com/index.php?resources/17851
Look at the wing wire frame, and be sure to look at lift for each segment. A cub needs other work as well.

Thanks for the link to this. I won't have time tonight to look at it but I definitely will tomorrow night.

Yeah Flexible did a good job making that plane harder to fly.

You can:

- Make the tail sit lower to make the plane more yaw prone.
- Give less authority to the rudder
- Increase "P" factor type entries and torque transfer
- Increase wing stall factors
- Increase flying weight.
- Adjust C.G., center of pressure...

etc..

All of this effectively "de-tunes" the model to give you more real world characteristics, instead of idealized behaviour.

Thanks for the help! I wish the stock models came setup to simulate real world situations more than an idealized behavior.
 
Then you would have everyone complaining how crappy the models fly.
Start with a good flight model then tune it to fly as bad as you want.
 
Then you would have everyone complaining how crappy the models fly.
Start with a good flight model then tune it to fly as bad as you want.

IMO, it's not a "crappy flying model" if it flies like the real word model it is simulating. If I'm not mistaken, Real Flight is a simulator...not a game, isn't it? I can understand people wanting to make models that fly easily, which is why I said that I feel the STOCK models should handle more realistically.
 
I have to agree with Phrank.

History has shown us that unless the planes fly perfectly people assume that the modeling is off.

Planes in Realflight are idealized, so they develope power levels equal to an optimally or "more than real life" plane, yet people come in complaining about the Realflight planes being "underpowered".

Also as an RC sim, novices already have a lot to deal with... so you know how that goes.

It's easier to "detune" a plane in Realflight once the model is perfect, than the other way around.
 
I have to agree with Phrank.

History has shown us that unless the planes fly perfectly people assume that the modeling is off.

Planes in Realflight are idealized, so they develope power levels equal to an optimally or "more than real life" plane, yet people come in complaining about the Realflight planes being "underpowered".

Also as an RC sim, novices already have a lot to deal with... so you know how that goes.

It's easier to "detune" a plane in Realflight once the model is perfect, than the other way around.

Oh, I hear what you guys are saying. I think I'm one of the few that tries to actually use RF to practice dealing with planes that have their own "quirks". It's still a great tool for learning many things about how to fly a plane/heli, though...it has sure as hell helped me out a lot.

BTW, Flexible, I just looked at the file you linked to. I had no idea you put that up the day after we talked about the problems I had with my AT-6 Texan. If I did, I would've grabbed it long ago.
 
Ideally, the Realflight developers could have an option for realistic vs. optomized (arcade) mode for each plane.

More work, but would give the novices and experienced pilots what the want...

I know this is a Realflight forum, but I purchased phoenix because some were raving about the free upgrades and the heli's being great.

I have found the free upgrade from v3 to v4 to be insignificant and while the choices of heli's are great they seem to fly way too easy and unrealistic. And the Planes seem way too hard to 3D, with the exception of a few.

It doesn't seem to have everything preset for the controller either. Like in realflight, typically you have idle-up ready to go when you try the model out for the first time. Their was no idle-up working when I first tried Phoenix. And while I like the idea of using my TX in the sim to add to the realism, it drains the battery and you use a memory location in the TX.

The best thing about Realflight and I"m not sure if Phoenix is similar or not, is the swap pages that some develop the variants to fly close to their real models characterisics.

Realflight has helped me a lot as a beginner and learning to fly 3D. But I was really hoping to get a "Real" feel for various style aircraft...
 
Lets say we both buy the same model airplane kit, you build yours and I build mine per instructions. There is a very BIG chance they won't fly the same at all.

Building techniques, glue, etc.

The point is, only a person who has bought and owned the real plane can really make the sim version fly the same.

How would KE know everybody's set up? (Somebody added a extra 1/2 pound of glue) LOL.

Mind you, you can get close with the editor.;)
 
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Lets say we both buy the same model airplane kit, you build yours and I build mine per instructions. There is a very BIG chance they won't fly the same at all.

Building techniques, glue, etc.

The point is, only a person who has bought and owned the real plane can really make the sim version fly the same.

Mind you, you can get close with the editor.;)

I realize this and my expectations would be that the developers actually fly these planes before they develop them or at least some of them. Or at a minimum have people test that have flown them, watch videos and study characteristics, etc. For example, I bought expansion pack #5 thinking that the Reactor Bipe EP would fly pretty close to the real thing and I could practice with this specific plane. Looking like the plane is of little significance if it flys like another plane...

That being said, yes my plane may be setup differently than the one in RF.

I believe that the same plane, equipment being equal and setup being equal will fly relatively close to one another. It's usually the components used, CG, battery, etc. that makes them different. Many threads have discussed the insignificance of getting things perfectly aligned and that minor offsets have little effect on the models we build. Of course, some of us are perfectionists and have to have things just so, but if your stab is slightly off or has a slight warp, it's only going to make a minor difference in flight characteristics.

I have taken warps and other such imperfections out of planes before and felt better about flying the plane in general, but only a very small change was noticed in real world flying.

Sorry for the rant, but I doubt if 3 of us built the Reactor Bipe that each would fly like a totally different plane. Many of us have rebuilt a crashed plane, and while it may never quite fly like it did new - I don't think it's going to exhibit coupling when it didn't before, etc. (Meaning things that are significant wont' change).

I"m just saying that while certain small tweaks should be expected, the stall factor, coupling and somewhat major characteristics of a given style of plane should be roughed out.

A simulation should be realistic IMHO.

Now, after I said all of that, for all I know the Reactor Bipe EP could fly exactly like the real thing when it's setup properly. However, I'm not the only one complaining the sim's version doesn't fly like their real models counter part.

If my model in real life is presenting a challeng holding a knife edge or other stunt, has wing rock, but in the sim it's a piece of cake - then it's defeating the whole purpose of practice.

Now, with regards to practicing stunts with helis, RF has been great!

BTW - this rant wasn't directed at you or anyone else (may RealFlight) - just venting my frustration. :D
 
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If my model in real life is presenting a challeng holding a knife edge or other stunt, has wing rock, but in the sim it's a piece of cake - then it's defeating the whole purpose of practice.
Rather than considering giving up on practice, maybe you should use RF to help investigate why your plane behaves differently.
 
Now, after I said all of that, for all I know the Reactor Bipe EP could fly exactly like the real thing when it's setup properly. However, I'm not the only one complaining the sim's version doesn't fly like their real models counter part.

I'd suggest setting up your REAL model like the sim!

I purchased the Reactor EP after flying it in the sim, hoping the real deal flew exactly the same way.

I noticed that the Reactor EP in the sim used a different motor than what the real plane called for... so on a whim I purchased the same one modeled in the sim.

Guess what? My Real plane performed EXACTLY like the simulated airplane provided by KE... I don't mean close either... It was EXACT.


If my model in real life is presenting a challeng holding a knife edge or other stunt, has wing rock, but in the sim it's a piece of cake - then it's defeating the whole purpose of practice.

Add about 1.5lbs of weight to the simulated plane, then up the power output about 20-30% to compensate, and then give it a shot... methinks you'll have what you are looking for.

Do this by equally increasing the weight in fuselage/wing/tail components.

BTW - this rant wasn't directed at you or anyone else (may RealFlight) - just venting my frustration. :D

Learn the editor... this is the BEST thing about Realflight.

You can make any plane fly EXACTLY like the real world counterpart.

There is absolutely NO difference between my real Addiction-X and the AV that I posted... but it took quite some time to get things to mirror my real plane EXACTLY.
 
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