markhamregular

Just venting! Many have told me here that flight simulators are never like the real thing. I know that. However, I have been practicing a Big Stik 60 with an OS 75 in Realflight 5.5 for a while and I loved the speed (95MPH) and thespeed the plane makes all the loops and rolls. Now that I have the real thing with the same engine, I noticed that the plane is not even making half the speed and the rolls are very slow. It’s not even giving me the speed I had with my old Stick 40 running on a OS46. This is ridiculous. That’s for sure the last time I make a decision based on a flight simulator. Just venting!!!

CGRetired

My Feedback: (1)

Well, as you said, the wrong platform to make such a decision. A lesson well learned.

What I believe most have talked about with reference to sims is that they are a good platform to practice with. The realism presented is well enough for that, but to use it as a source for data on the real thing, well, I would not do that. What I would do is after I buy a plane, find one like it or similar to it on a sim and play with it there.

Now I had a Goldberg Wild Stick 40 that I put an OS .50 on board. The thing had flaps (real flaps, not flaperons). When deployed, I could do a loop in what looked like the length of the plane. Rolls, with dual rates, woud snap around. But, with the sticks, and the thick wings, I can't see how anyone could get that sort of speed out of the airframe. I have a very slippery Venus II and I don't think I would be able to get 75 mph out of it. But that's not what I bought it for. It is an intermediate sized pattern plane and is very capable. AND, it is on Realflight and I do practice with it on the sim.

CGr

traiders

My Feedback: (3)

What prop are you running? OS 75 should not have any problem with that plane.

jester_s1

You might also notice that the Real Flight sim assumes some pretty big numbers from the engines. If the sim is calculating top speed for 18,000 rpm, then 95 isn't too silly. But most of us run around 12,000 on the top end and that's going to result in a speed reduction for sure.

CGRetired

My Feedback: (1)

Yes indeed.

Take the pitch of the prop, which will give you the ideal distance a prop will move in one revolution (for example a 13-6 will give you six inches of movement in one revolution).

Take that six inches per revolution at 12,000 RPM means 12,000 X 6 = 72,000 inches in one minute or 4,320,000 inches per hour. A statute mile is 5280 feet or 63,360 inches, well, simple math will use 4.320,000 divided by 63,360 = approximately 68 statute miles per hour. And that's ideal, no slippage. So, that's the MAX the plane will go with that prop rotating at 12,000 RPM. A more realistic speed would be somewhat slower.

CGr.

1320Fastback

Is the motor broken in?
What fuel?
Throttle barrel is opeining fully?
What glow plug?
What prop?
Prop balanced?
Are you flying in wind?
How do you know its not going 100MPH?

rcjetflyer0718-RCU

My Feedback: (1)

Yeah Realflight is realistic the Twinstar with 2 OS 40FP turns 21000rpm and flies at 125 mph!!!

ameyam

RF models your airplane pretty close if you get all the variables the same- the engine, prop, CG, throws, servos etc. Thats just too many variables so it will not perform exactly the same. Remember, the simulator is there to help you build muscle memory. The remaining disciplines you need to build on the airfield. In the simulator, restarting after wiping out is just a button press away


Ameyam

markhamregular

I have a 12-8 prop. I had a 13 on it which is the smallest as per the OS manual but my instructor told me it was too big.

I did the break in myself. It was hard to reach for the rich and the lean back and forth.

I have to say it's my 4th OS engine but the one I had the most problems breaking in.

After the break in, the next 3 trips on the field have been nothing but trouble. Engine would not start. Tuning was a pain.

Each time I had someone else tune it for me. The idle needle was way off (way too rich).

But now the engine is running better. I can only guess the speed. I fly my Escapade that reach about 65-75 MPH.

This Big Stick is not anywhere close. I usually run my planes like my boat (cruising speed around 75% throttle).

I think WOT will damage the engine in the long run. Am I wrong?

It's not just the speed. The maneuvers are way slower than my previous Stick 40. Maybe I need to put more throw on the ailerons.

Villa

If you do not add wind to the simulator you will notice a BIG difference.

el_xero

My Feedback: (2)

Hey, sorry to hear about your gripe I know how frustrating it can be sometimes. But listen as someone said earlier there are plenty of variables which you can tweak to get the best performance out of your model you gotta read read and experiment. First off the Throw of your surfaces will affect how much that bird rolls... faster servos might help or adding in positive expos could help (be very careful with expos though) As for the engine, from the description only, id say it's completely broken in just yet give it some more air time and see what happens. Read up in forums aobut the engines and see if anyone has done some actual testing of different props for that engine and see which prop (brand) pitch and type gives the best bang. There really are many many variables but I'm sure if you get that plane set up just right it will give you very close to what you're looking for. I've just heard too many good things about it for it to turn out disappointment for someone. And yes.. wind will make a big difference as someone else stated earlier.

Live Wire

Check your center of gravity and thrust line, that will throw every thing off.

lopflyers

My Feedback: (12)

More throw on the ailerons will make the rolls sharper.
The prop size, the full opening of the throtle barrel and the stick to full throtle will take you there on the speed.
What are you using to measure speed? Those baseball speed guns are not to accurate[:-]

DenverJayhawk

Go to the physics in the RF sim and turn it up to greater than 100%. It'll be much more snappy with the rollers, etc. I don't know of that will change your maximum mph, but it will make everything more more responsive. Conversely, turn the physics speed down to get the sim to match your actual Big Stik 60.

MetallicaJunkie

i have yet to fly a plane that flys like the way it does in a sim..... NEVER base a purchase on how it flys on a sim

CGRetired

My Feedback: (1)

FYI.. this is a quick calculation of the maximum speed for various props at various RPM's. This is theoretical and, because of such things as drag, slippage, and fuselage/wing design, are not attainable. You won't reach it, but, in theory, in a perfect world, well, you get the idea.


Pitch RPM MPH

4 8000 30.3
6 8000 45.5
8 8000 60.6
10 8000 75.8
4 10000 37.9
6 10000 56.8
8 10000 75.8
10 10000 94.7
4 12000 45.5
6 12000 68.2
8 12000 90.9
10 12000 113.6
4 14000 53.0
6 14000 79.5
8 14000 106.1
10 14000 132.6
4 16000 60.6
6 16000 90.9
8 16000 121.2
10 16000 151.5

opjose

If you download the AV ( on the Realflight Swap Pages ) that I posted for my Big Stick 60 using a SuperTiger 75 engine, you'll find that it produces EXACTLY the same flight speed and power as the real thing.

The sim CAN be INCREDIBLY accurate, but all to often the engine specs reflect what the manufacturers STATE, and not what we see in the real world... hence what Jester_s1 says is right on the money, yet the sim is otherwise extremely accurate.

The Physics model I posted adjusts for differences. The actual airfame model only needed a small amount of tweaking to produce real world results.

markhamregular

opjose,

Yes this is the model I downloaded. All I did was changing the engine on the sim to an OS 75AX.

opjose

The default OS 75AX power curve is wrong... it reflects what OS claims in their advertising, but that is highly unrealistic.

Leave the AV as I posted with the SuperTigre setup, it is identical to the 75AX performance, rename the ST75 to OS75AX_Realistic if you want....

Also note the prop I'm using... that's the best combination I've found for the Stik in real world testing of various props on a 75 engine for that Stik.

BTW: My real world Stik/wST goes from a crawl to a decent fast speed, but it is not a rocket. On the other hands my take-offs are straight up and I have no problems torque rolling my Big Stik...

opjose

I've found many where the opposite is true...

I've purchased a few electrics because I was quite impressed with their behaviour in the sim...

However I also noted that the modeled electric motors were different than those spec'd from the manufacturer...

For my real world plane I opted to purchase the sim modeled motor/electronics and found that this exactly reproduced the behaviour of the plane in the sim yielding much better performance.

Methinks that because electric specifications given in advertising, far more closely reflect actual observed results, when those specs are applied to electrics in the sim, we see similiar behaviour... however the same is not true for glow or gas...

That said, other than the power/motor modeling the physics modeling is amazingly accurate, with planes in the sim producing second and third order effects ( quirks ) that we see in the real world...

e.g. Adjust a 3D plane for a neutral C.G. and it will tend to ballon up in the sim on landing just like the real deal...


With a bit of skillful "tweaking" you can get uncannily accurate behaviour...


I sat with a powerful laptop all day at the field, and an Alpha 40 doing the physics for the Alpha 40 on the swap pages....

Flying each, doing the FAI trimming guide on both, etc.

I wanted to get everything right so I could let kids practice with it on the sim for a summer camp we run...

IMHO this resulted in the single most accurate trainer in any simulator.

markhamregular

Opjose,

What prop do you use? For sure, I will fly the sim with the SuperTigre and compare.

Thanks,

opjose

As I write this I don't remember... but it's the same prop I modeled in the AV.

I tac'd the plane with that prop both on the ground and in the air to get the curve as close as I could.

DenverJayhawk

the only problem i have with RF5.5 is I'll 3D stuff a few feet from the ground that I would never try in real life with a $600+ model.

bigdanusa

If you're looking for speed then get one of these.....

http://www.youtube.com/watch?v=dTHWBSluUjU

opjose

The Big Stik is not really a "high speed" plane... particularly because of it's thick wings and uncowled engine.

With the ST75 or OS75 it will unload in the air using a high pitch prop producing a good clip, but it is not blindingly fast.

Using the modeled OS75 in the sim, the plane will unload to the point the engine is running at 18000 RPM or so, something the specs say it can do, but we NEVER see in real life...

On the AV the Power Curve in the ST engine prevents the engine from reving over 140000 RPM even when unloaded, which more realistically reflects observed behaviour.