Breaking props and ganged motors in RF question

Fly_electric

Fly_electric

Well-known member
Two RF questions.

Having crashed once or twice now (that would be a metric once or twice ;) ), I see the propellers never break on impact. Is there a physics adjustment for that or is such super strength intentional?? Wings sheer off under high load, so would it not be realistic to simulate a prop blade being thrown off? Rare, but it does happen.

In the real modeling (and occasionally full size aircraft) world, two motors/engines are ganged side by side to the same propeller shaft. Can that be simulated in RF from the physics?? That thought stemmed from doing E conversion work in the Henschel He P.75 (where it seems the torque of the counter rotating props do not cancel...).
And a close cousin to that question is whether it is possible to create new motors in the physics settings? AXI made (maybe only for custom orders), a two motor in line out runner and I don't think it is one of the motor choices.


Thanks
 
In the case of the Henschel He P.75, The torque does in fact, cancel out.
the problem is a lack of yaw stability. this is corrected buy adding two additional
v-stabs, symmetric to the middle on, yet equidistant from it on the X axis.

Although you probably have no clue what the big words mean, it helped.
See my AV here. https://forums.realflight.com/index.php?resources/16824
 
Thank you brields. Yes, I do know what the big words mean, and am working on another model that has a stability issue on the yaw axis. It is not uncommon for some scale plane to have YS issues, due to the obviously smaller fin-- so much so that in some cases a removable clear plastic extension is added for the flight part of a scale competition (a variant of your solution). This design has a large fin and therefore it did not immediately occur to me that YS was an issue.
Adding fin area does indeed help, but I am also interested in seeing what can be done (if anything) in using the power of the software radio to compensate.

Norton, yes we are off topic but only slightly in that my side thought about the Henschel He P.75 flight characteristics were triggered by it having two engines.
Thanks for the Wyvern link. Did not know about that plane in the swaps.

The two original questions remain:
1. Is there a RF option to simulate prop breakage/failure
2. Can multiple motors driving a common prop shaft be simulated in RF

Thanks
 
The Wyvern suggestion proved to be off topic related in that the original aircraft design may have had YS issues: large vertical fin + additional fins on the stab..
Have not ever read that it was so, but perhaps that's why the Connie had 3 rudder/fins??
 
Do be careful with Brield's replies, Fly_Electric. Links he posts may be one thing, but his answers are usually wrong. It'd be nice if he'd put that as a disclaimer in his signature.
 
Fly_electric said:
In the real modeling (and occasionally full size aircraft) world, two motors/engines are ganged side by side to the same propeller shaft. Can that be simulated in RF from the physics??
Click to expand...
Yep.

https://forums.realflight.com/index.php?resources/6969

Even modeled...
image15_yU4.jpg
 
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The Bugatti model does have an interesting feature in showing two motors connected together. However, there are still two motors and two props, so it's not quite the same idea I'm asking about. A real world example was the HE 177.

The Bugatti model BTW is very nice. It seems planes made for older versions of RF such as 3.5 and 4 were a little more forgiving about designs with weaker yaw stability, vs RF6. Adding larger physics fins seems to be the norm in bringing some of these nicer planes from the past into the present version. So I made a physics change for the the Bugatti and posted it on the swaps. Not crazy about the way the physics look, but it seemed to take that much extra area.

Getting back on topic, am still looking for info on details (if it is possible) of two motors driving a single prop shaft (and one propeller). The prop blade breakage question also remains.

Thanks
 
I don`t know if it`s what your looking for, but I did add a second motor in the Parkzone Reliant AV that I made a while back. It did make a difference in speed, which, is was what I was looking for. Downside, when you crash, the added motor will still be running. Hitting the "K" key will kill the motor as usual though.
There might be a fix for that issue, If so, I don`t know it.
 
UT,
What I see in the physics are two motors, each with props. One prop is of course invisible (make sense since there is only one engine in the graphical model, and likely is the engine that stays on).
Sooo, that technique is close, but not quite the same as what I am asking.

If RF does not allow 2 motors/engines driving a single shaft & prop, can such a motor/engine be created and become one of the physics choices?
 
Is this what you're referring to?
AXI5330D20.gif


If so, wouldn't a more powerful motor do?
You can edit your own custom motor to any parameters you choose. :confused:
 
I think people get hung up on virtual planes needed to be set up in a real fashion. For example in RF, it could be set up as an electric, but show a nitro motor.
 
Doesn't the AXI permit the motors to be ganged OR to be set up in a contra rotating fashion?

---

I agree that a "two motor" request to drive one prop is a bit useless since you can merely take the agregate power characteristics and apply that to a single motor.

As far as countra-rotating, that of course has already been ( easily ) done, as in the case of the VFO and the other examples given.
 
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Fly_electric said:
UT,
What I see in the physics are two motors, each with props. One prop is of course invisible (make sense since there is only one engine in the graphical model, and likely is the engine that stays on).
Sooo, that technique is close, but not quite the same as what I am asking.

If RF does not allow 2 motors/engines driving a single shaft & prop, can such a motor/engine be created and become one of the physics choices?
Click to expand...

FE There are two engines in the physics, (each comes with a prop) one prop made invisible (the engine/prop I added) via the "props visual scale" ( the blue,in the editor), I reduced it to 1
In the graphical/wire frame model, both engines show. The one I added is just aft of the CG. Highlight the top engine in the physics, and you`ll see the rear/added engine"glow" ??, on and off in the wire frame model. IT is the engine that still runs in the event of a crash. There`s probably a way to kill a second motor in an AV, in the event of a crash,(other than the"K" key) I just don`t know how to accomplish that in the editor. After all, RF it does with there stock multi engine aircraft ??
What you might want to try on the Reliant, is to reduce the prop Dia. and pitch to there lowest allowable amount, on the added motor, thus making that prop useless, and increase the pitch/dia. on the front/stock motor.
Using the Nav guide, you can see if there is any diff. in air speed with that configuration. I will say though, I doubt that the second motor is driving the shaft of the stock motor ????. I can`t recall if I tried that , when I made that AV.
Just remember, it`s what we see visually in the sim that counts. Soooooo...............to answer your ??,..If it `s not on the torque generator/engine menu, then you can`t have it.This might be as close as the sim/RF allows you to get to your goal, to my knowledge. But I could be wrong. I`m not a physics guru.
The Reliant was my first attempt at physics for an AV. We are limited to motor choices/configurations in the editor after all, and in the real world, I don`t see two motors driving one shaft/prop, in a plane, very often, if at all (although, I`m sure its been done).
That could be why someone came up with the novel idea of a multi cylinder engine. (two engines in one ?? who woulda thunk that:eek::eek:)
What is it that your trying to achieve FE. We might be better able to help you, if we know what your end goal is.
 
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Thanks to all.

The thought started out wondering if a more powerful motor might be used in the sim. Don't have a specifics in mind, but just the idea. It may be the choice is in there for a particular application, but that's a lot of motors to click and check. A cross reference list of all the motor details or search/sort ability would be very handy (search/sort would also be nice in airfoil selection). A more powerful motor is the one phrank shows, but unless I've missed it, it's not in the list of choices. Was not aware (am now thank you) that we can edit our own motors, so that lead to the idea of ganged motors on a common prop shaft.

It's a case of my trying to push the limits of what the sim is intended to do (spot on Jeff). An earlier thread discussed the option of separate battery packs for each motor in a twin (good work around was found there, and my thanks to all for their comments & suggestions). Same thing here. I think the sims physics are such that the power systems are treated as independent units: battery/fuel + motor/engine + prop, and no provision is made to interconnect them as might be done in the real world. The visible motor pair in the Bugatti (excellently displayed & animated BTW! Would like to learn more how that is done), was very close to what I wondering about: two motors side by side, driving a common gear on the prop shaft, but with only one PS & prop. The question was can such an arrangement be put in the physics, and the answer is apparently no. The workaround (thank you phrank) is to edit a custom motor.

It's all about how the plane flies in the sim, and I'd forgotten that.

Prop blade breakage:
Why there is no provision for prop blades to separate (even if only in a crash) is probably better asked of the folks at Knife Edge, but perhaps others have wondered the same thing, and have not asked? Can the blades on a folding prop separate from the hub? Comments Knife Edge??

Thanks to all for your comments and patience.
 
An easy fix for more power is to just increase the torque percent . I believe it goes up to 200%. Then simply adjust the prop to the new found power.

About the yaw issues.... I would try increasing the drag on the V-stab
 
Fly_electric said:
Thanks to all.

It's all about how the plane flies in the sim, and I'd forgotten that.
Click to expand...

Ultimately that's what it's all about.

When the fidelity of the simulation mimic reality very closely we start thinking about things in the sim as if we were using real world analogs.

If anything this is a testament to how well we are fooled by the programming.

The results of this foolery can also be a bit humorous too... especially when people draw parallels that run far too deeply.

You sometimes have to remind people that "it's just numbers!". Heh....


Fly_electric said:
Prop blade breakage:
Why there is no provision for prop blades to separate (even if only in a crash) is probably better asked of the folks at Knife Edge, but perhaps others have wondered the same thing, and have not asked? Can the blades on a folding prop separate from the hub? Comments Knife Edge??
Click to expand...

Me thinks there be a "feature request" in there... :)
 
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