How much does smoke oil weigh ?

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How much does smoke oil weigh ?

Post by Strava » Thu Dec 21, 2017 8:42 pm

I added 1 smoke generator to the cub.
But, when I set the smoke oil weight to anything other than zero it can't hardly get off the ground.

I have tried 1kg all the way down to 0.0001kg and it makes very little difference.
Even at 0.0001kg I can just barely get it to climb a little with out stalling.

Any ideas what might be wrong?

(the crop duster version of the cub has 100kg of smoke oil and still flies OK.)

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Re: How much does smoke oil weigh ?

Post by Scarecrow » Thu Dec 21, 2017 9:28 pm

In real life, each US gallon of smoke oil weighs about 8 lbs (3.63 kg).

Obviously the capacity in which an aircraft can hold depends on the size of the tank. Usually ranging 3.5 gal to 8 gal. I have flown a Super Stearman with a 25 gallon smoke tank. For a Piper Cub, I imagine it would be a 3.5 gal tank so your total smoke oil weight would be 28 lbs (12.7 kg).

How well this converts to YSFlight .dat files, that I do not know. They're too wonky for me.

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Re: How much does smoke oil weigh ?

Post by decaff_42 » Thu Dec 21, 2017 9:44 pm

It should work without the smoke oil parameter. All the stock DATs I've looked at don't have smokeoil along with the smokegen parameter.

That being said, I'm not sure how the smokeoil parameter changes things...will probably need to be tested :D
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Re: How much does smoke oil weigh ?

Post by waspe414 » Thu Dec 21, 2017 10:08 pm

As best I can tell, the SMOKEOIL line doesn't actually change anything about how the aircraft performs. It loads 100kg of smoke to the aircraft by default, but changing the value has no effect on the loaded smoke oil weight. Loading smoke to an aircraft without SMOKEOIL also adds 100kg of smoke to the aircraft. I would guess this is a holdover from the early development of YS.
EDIT: It was added in the 2002 version, but the value of SMOKEOIL has no effect even in that version, with the exception of SMOKEOIL 0.0kg unloading smoke by default. From the start smoke has weighed 100kg.

At any rate, it appears to do basically nothing. If you have issues with the .dat and want me to look it over, toss it on up here.
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Re: How much does smoke oil weigh ?

Post by Strava » Thu Dec 21, 2017 10:49 pm

Thx to all for the fast replies.

OK, so smoke oil is either 0kg or 100kg.
So maybe 100kg is more than the cub can lift.
So, i tried reducing the clean weight by 100kg to compensate.
This should net out to a zero change in weight.
But that made no difference.
It still only gets a few feet off the ground and won't climb.

Something is wonky with smoke oil.

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Re: How much does smoke oil weigh ?

Post by Flake » Thu Dec 21, 2017 11:27 pm

AFAIK, Smoke Oil Weight does NOTHING for the computation of weight in YSF.

If Smoke Oil Weight is 0, you won't be able to draw smoke at all.

What is the Clean Weight and Payload Weight and Fuel Weight according to the DAT of your aircraft?

Can you supply the DAT Code for investigation/testing?

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Re: How much does smoke oil weigh ?

Post by Gunny » Fri Dec 22, 2017 1:53 am

Looks to me like Soji coded SMOKEOIL to be either off [0kg {FALSE] or on [100kg [TRUE] using weight as the definition, so entering any +/- of that really has no meaning to the computations, so you either have a flight or no flight [Over weight] situation.Just my opinion I have no proof to back it up. ;)
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Re: How much does smoke oil weigh ?

Post by Strava » Sat Dec 23, 2017 4:03 am

Flake, if you would like to do some testing, download my version of the cub that I posted here a few weeks ago.
That is the dat I am trying to add smoke to.

I think Gunny is right. Smoke is either on and 100kg or off and 0kg.
I did some tests with the stock eclipse to try and check this.

My test procedure is:

Apply full throttle.
Taxi to 80kts.
Pitch up until the vertical speed starts to go up.
Start timer/stopwatch.
Control pitch to maintain 80kts to altitude of 1000ft.
Stop timer.

Her are some results listed as time in mm:ss and comments on the conditions of the test:

1:00 baseline stock eclipse
1:23 add smoke in loading screen
1:26 smoke=10kg in dat
1:27 smoke=100kg in dat
1:26 initload=100kg in dat

I would accept all of the 1:2x times as equal and say the smoke is always 100kg.

So how to compensate to keep the perfomance the same?

How about adjusting WEIGHCLN ? I should be able to subtract 100kg from the total weight for a net change of zero.

1:15 smoke=100kg WEIGHCLN=630kg-100kg=530kg
1:10 smoke=100kg WEIGHCLN=630KG-200KG=430KG

That helps but even subtracting double is not enough. It also breaks the laws of physics :-p

How about the WEIGLOAD variable? I am guessing this defines the how much payload the plane can carry.

1:25 with WEIGLOAD values from 0 to 500 !

So WEIGLOAD is not used at all.

Adding 100kg to the fuel load also had no effect

1:00 weigfuel=200kg

I do wish we could get an accurate explanation for these variables and how they interact with each other :(

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Re: How much does smoke oil weigh ?

Post by Gunny » Sat Dec 23, 2017 6:23 am

Sorry, my friend but flight physics in ys is an oxymoron.Any resemblance of ysflight to an actual flight simulator is purely coincidental and completely accidental.That is why a piper cub can fly at Mach 1 and not self-destruct.Also why just about anything is possible in ys.Even flying condiments ;)
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Re: How much does smoke oil weigh ?

Post by decaff_42 » Sat Dec 23, 2017 10:27 am

I do wish we could get an accurate explanation for these variables and how they interact with each other
I've been working on that for a while now and I have made some headway.
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Re: How much does smoke oil weigh ?

Post by waspe414 » Sun Dec 24, 2017 4:50 am

I just ran some tests. It turns out the values of clean weight, fuel weight, and payload weight have no effect on the lift/weight calculations. It does affect aircraft acceleration (thrust/mass) and speed/altitude though. Because smoke is classified as a payload, it does affect lift/weight calcs. Really the only way to have it fly properly with smoke is to change the actual flight performance of the aircraft.

Decaff and I are looking into this more.
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Re: How much does smoke oil weigh ?

Post by Flake » Sun Dec 24, 2017 11:13 am

Ohhhh yeah, we getting some YSFlight Physics Experiments going on here now. Full on Michelson-Morley Bro.

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