Flight dynamics question for the experts

michaelvader

michaelvader

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Hallo Friends,

on the Dornier Do-24 I experiance a strange phenomen for this aircraft:
When I icrease throttle the plane drop the nose to dive.
when I decrease throttle the nose comes up for the aircraft to climb
both caracterics are very pronounced
After reading the german factory manual of the Do-24 (it could be found there:http://www.deutscheluftwaffe.com/archiv/Dokumente/ABC/d/Dornier/Do 24/DornierDo241040.pdf ) the ac should not show the influences of the throttle to the pitch stability.
How can I change this behaviour in the aircraft.cfg of air file?
It might be interesting to have possibility to act on this behaviour.
The Do-24 should be not affected by the change of the throttle,
but on the Messerschmitt Bf / Me 109 series it could be interesting
and on the Ju-52 I experianced the pilot to adjust pitch trim according to the power setting.
I hope that somme expert can help me to see clear with that little proble

Yours

Papi
 
The microsoft simulators tend to really exaggerate the relationship of engine position & power input versus pitch (or attitude.) In the real world, some high wing/high mounted engine aircraft can push their noses down when power is added, lift their nose when power is reduced, but this can be a big variable depending on how the aircraft is loaded, what type of lifting design and dimensions. Lighter aircraft like the Grumman Goose & Widgeon can be quite susceptible to these handling traits, whereas larger aircraft ( Martin Mars.......) not so much, if at all. But the flight sim tends to exagerate the potential unless setup with care.

The Dornier 24 is a really interesting aircraft when you look at it's profile. For a high wing seaplane, it's actually quite flat. The wing is raised just enough to clear the propellers, which themselves are not such a great diameter. The fuselage is quite shallow in depth, and along with the sponsons, provides a very strong lifting body. This, coupled with a very generous wing area and a tail that curves way up to directly intercept the prop wash, it makes sense that the aircraft would ride up and down with the flat attitude of an elevator.

Another seaplane with a similar design solution from that period is the larger Kawanishi H6K Mavis.

The fix may or may not be straight forward. Without actually looking at the flight model, the guessing could fill a page. If you let me know exactly which model you're dealing with, I could download it and have look.
 
Hallo,
the topic seems more complicated than I thought
the concerned model is this one: Dornier Do24 T3 FS9.zip
I would be interested of course the problem to be solved but also how it would be solved
yours
Papi
 
I think if the aircraft.cfg places the engines correctly vertically then without any angle correction of the thrust line then you could experience that phenomena. I have not found the capability in FS9 or FSX to apply an angle so one must falsify the vertical position - or within the .air file section 1101 pitch section adjust the thrust effect of either nose up or nose down.
Keith
 
I thought for sure that I'd seen something like this before, but I can't find it now. My suggestions would be to increase pitch stability in the tuning section, and if you're not already doing it, make slower throttle changes.
 
Well....let's give this a try.

The power on/off angle of attack response that you didn't like is still present, but massively reduced. This

was done by first resetting the inflight center of gravity (up two feet, aft one foot), and then stretching the

"empty weight" center of gravity forward four feet, and up four feet.

It's way more than the aircraft would display in real life, but perhaps it's a way of compensating for the lack

of any setting to introduce a degree of incidence for installed engines & thrust, and fooling the sim. If we

stretch it out further....one could probably eliminate the undesired effect all together. But the numbers are

becoming so cartoonish that it disturbs me.

Using Aircraft Container Manager, I quickly setup the wings, tail surfaces, and engines to match the graphic

model. Six crew member weights have been positioned.

I was having an aircraft crash during takeoff at around 70 kts. I checked the contact points and found that

they were doubled up....(two per position...) I removed the duplicates....the crashes ceased for me. Plane

still floats like it did before. This one came with no crash points....I'll leave'em out for now.

At one point I fed it into AirWrench....and kept some of that. It's a melange of the original flight model,

with a little AirWrench, and some hammer work of my own.

I'm a bit busy right now to cook up a totally new flight model from scratch for lovely Dornier (Thank you

Shessi!!)....but I may do so a little later on. As it's set up now, I don't like the low speed handling at

stall. The engine power-band doesn't seem right, transition from power to deceleration seem a little

unresponsive, almost like a jet. The real Do.24 does not feature a low drag coefficient....what with turrets,

struts, a big flat windshield, etc, etc. It's sort of a really impressive flying barn door with turrets...

I added a little drag (not even close to enough!!) as an emotional response. I didn't compensate the engines to

preserve the airspeed....if you'd like it faster, go into the aircraft.cfg and adjust the engine power scalar

for a quick fix.

Gotta run, there's a Vultee racer in the oven, and my favorite TV show is just on..!!

View attachment Do24T rebalance.7z
 
Halloo Friends, Hallo Magoo,

thank you for your interest and help!
I tireid out the attached moddified files.
The pitch changes are less, Allright,
Now I will try to give you some more details I take from the Dornier Do-24 T3 factory manual:
Take off with 1.5 ata and 2500 rpm, flaps set to 20°, pitch trim should be set to +2.5°, take off weight 13700 kg, speed should be 120 km/h
after 1 minute reduce power to 1.25 ata and 2250 rp, climb speed should be at 175 km/ to 195 km/h
after 30 minutes reduce power to 1.10 ata and 2100 rpm cruise spedd should be about 295 at 2600 meter altitude
Climb time to 2000 meter in 6 minutes
to 4000 meter in 7,2 minutes
I hope those indications might help you to work on the fde
If one needs further informations, please ask me and I will try to find out what you need more
Yours
Papi
 
FDE

Mr Vader,
I didn't have to wait for the 'Acme' specs - made up my own (ha). Here is my offering. At MediFire. 8 kb. Hope this meets your expectations. I don't need approval. A six pack will do. But I can modify it further per your instructions. Want it to go 335 kts? Let me know. After I tweaked it I played with it so much it got late (4 am). Link: http://www.mediafire.com/file/9osybf4hblz75ly/DO-24C_FDEs.zip . A note if something is wrong / not right would be appreciated. Enjoy.
Chuck B
Napamule
Edit: Just noticed 'panel=hjaFI'. Please delete name, after the '=' sign. Sorry.
 
Error

I noticed the engine numbers were '0,1,3' in cfg. Please edit to '0,1,2'. Sorry about that. If you want to stop the center engine (as in real) do 'E+3', then 'Ctrl+Shft+F1'. I am in the process of tuning the engines to (close to) spec and want to match model with actual engine position (smoke). Might not influence how it handles, but just caught it. And it has too much fuel (by 6,000 lbs!). Redoing how it sits in water, too. It is too high (watched youtube video of real one). I really like the looks so it's worth it. Will post MediaFire link to improved (?) FDEs tomorrow.
Chuck B
Napamule
 
@napamule,
thank you to have also lokked at the fde of the do 24.
I made a new entry in my aircrafts to test your version of the fds.
hummm there might be an misunderstanding from the datas I wrote here.
the speed and altitude datas are german metric units km/h = kilometers per hour.
so with your speed the germans would have been glad to have such a fast hydroplane.
Thats always a challenge to translate the german units to us units
Yours
Papi
 
With due regard for maintaining true aircraft performance, a small adjustment to the engine location should improve what looks like too much nose down affect with increased engine power. Just make a backup of the cfg first. Using Erwin Welker's aircraft (do24t3_fsx.zip), in the engine section of the aircraft cfg:

[GeneralEngineData]//0=Piston, 1=Jet, 2=None, 3=Helo-Turbine, 4=Rocket, 5=Turboprop
engine_type = 0
fuel_flow_scalar = 1.00
min_throttle_limit = 0.0
engine.0 = 9.33, -14.20, 10.60,
engine.1 = 9.50, 0.00, 10.80,
engine.2 = 9.33, 14.20, 10.60,

the numbers in red designate the vertical engine position. You can reduce each by say 1.00, save the result, reselect the aircraft and see the nose down effect lessen. Just keep reducing the numbers until the aircraft becomes more manageable. Again, if doing this alters the real aircrafts behavior then just leave the cfg alone. Magoo applied the same thinking but left the engines and suggested editing the CoG parameters, effectively achieving a similar result to above.
 
Well I did not change the Ref Datum. That would mean re-doing the contact points, the fuel tank locations, the engine locations, the lights, the views and the smoke positions. And if he did not consider load being OVER due to fuel, then what's the use. Ref Datum & CofG changes are not my cup of tea. I reduced the fuel load, etc. And I moved the engines. Now it does not exibit that behavior. Had to 'cheat' and use bogus specs, but it worked. Still working on it though. See below for my engine positions (Notice I moved them BACK too). And if you want smoke to come out accurately you would need to use the commented out lines. And this (engine position '12.500' vertical) IMO, is the REAL reason for the behaviour. I will finish tonight. Probably post around 10 pm as I will be busy with RL.
Chuck B
Napamule

[GeneralEngineData]
engine_type = 0
Engine.0= -2.600, -13.000, 1.500 //Left
Engine.1= -2.600, 13.000, 1.500 //Right
Engine.2= -2.600, 0.000, 1.500 //Center
//
////---For Accurate Start Smoke ..... use Below ---
//Engine.0= 2.600, -13.000, 12.500 //Left
//Engine.1= 2.600, 13.000, 12.500 //Right
//Engine.2= 2.600, 0.000, 12.500 //Center
//

Edit: Delay? Well...was playing with taking off and landing using AP. It will take off on it's own. Ha! Set 1 of flaps. SPD to 250. ALT to 2500. VS to 1200. Remove parking brake and click AP button. (Remember to remove flap and raise gear (optional) on climb out. Sit back and watch it do steep climb, level off and hit cruise - Look Ma No Hands! Landing is at: Full Flaps, SPD to 80, ALT to 0.000, VS to -500 fpm. When at aprox 100 ft click AP off, dial in +3.0 pitch trim, cut throttle and it lands at 70 kts preatty as you please. What you say your FDEs won't do this? Well wait for mine. Mine do (hehe).
 
Mr Vader,
Here is spec:
Performance:Maximum speed: 340 km/h (183 knots, 211 mph) at 4,800 m (15,750 ft). Cruise speed: 264 km/h (159 knots, 183 mph) at 5,400 m (17,720 ft). Range: 2,700 km (1,459 nmi, 1,678 mi).

If you want slower boat just change the power and thrust scalars to '=1.000'. I like a little faster speed for my ac so I put in new and bigger engines in mine. I can't see cruise at 159 kts - not with 3 engines! Oh, and if you see a spoiler it's for a Water Braking, not sub for flaps. OK? OK!
Chuck B
Napamule
 
Hallo Friends,
thank you all for all you help.
For the moment I fly to different Do 24. one is the original with my repaints and the modified fde by James.
The other is called Do 24 V5 and flies with german paint and luftwaffe cockpit, with this one I try out the
FDE by Napamule.
In fact the whole ac merits a complete a complete rework.
For the moment I rework my panels, mainly the flight engineer panel.
It would really fine if we can find together to make a crew for this projekt.
A lot of well done Catalinas exist, freeware and commercial ones. why not to make a really fine german counterpart?
And we should not forget that it was firstly build for the dutch forces.

Yours
Papi
 
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