K4: Inverted Flight Mechanic

[Crumpp]

Most modern aerobatic aircraft simply put a weighted tube on the end of the pump pick up. This allows the tube to fall to the "bottom" of the tank and pick up fuel no matter what the aircraft's attitude.

 

http://www.aircraftspruce.com/pages/ep/fuel_tanks/flopetube.php

[IIIJG52_Otto_]

I thought I read some where here that the K4 cannot fly inverted for more than 10 seconds as the engine would cut out.

 

My question is: Is that true, because I was under the impression late model 109's used direct fuel injection systems which was designed to allow later model 109's to fly inverted.

 

Note: This feature was available on 109G models.

 

If that is true, why is this not modeled on the K4?

 

Or is it modeled?

I am claiming this issue for months, a Bf-109 is capable of flying inverted 34 seconds Without problems.

According to the Danish authority report about the incident occurred to a Bf-109G of the Flugmuseum MESSERSCHMITT in Roskilde AirShow in 2013. That Bf-109G was able to fly inverted 10 seconds and 24 seconds more with the fuel lines P1 and P2 filled with air, before engine stop. Total time of 34 seconds with electrical pump P2 in OFF.

 

Page.Down, you can read my post here.:thumbup:

http://forums.eagle.ru/showthread.php?t=140651

[sobek]

Have you tested the DCS 109 with less than full throttle?

[Siegfried]

I did but I don't remember the exact numbers.

 

Automatic RPM at 1000 meters. 1.8 ata was something like 4 seconds and 1.1 ata was 8-9 seconds I guess. But sure that is dependent of throttle position.

 

I must repeat the test.

[Ala13_ManOWar]

I am claiming this issue for months, a Bf-109 is capable of flying inverted 34 seconds Without problems.

According to the Danish authority report about the incident occurred to a Bf-109G of the Flugmuseum MESSERSCHMITT in Roskilde AirShow in 2013. That Bf-109G was able to fly inverted 10 seconds and 24 seconds more with the fuel lines P1 and P2 filled with air, before engine stop. Total time of 34 seconds with electrical pump P2 in OFF.

 

Page.Down, you can read my post here.:thumbup:

http://forums.eagle.ru/showthread.php?t=140651

 

Have you tested the DCS 109 with less than full throttle?

Actually Otto and I tested together the feature this evening online, and it was quite better than previously thought (1.2.16 Beta). Inverted flight can be kept by 10-12 seconds with 1.3 ATA (-1G), then fuel pressure drops and you have a while to level wings and keep flying without further notice. Once levelled fuel pressure rises quite fine and quick (fuel pumps on). With idle throttle I was able to keep some 45 seconds without problem :music_whistling: may be more, then you can see fuel pressure starting to drop but quite slowly so you are plenty of time to level wings and keep flying with no problem at all. Of course again trying to keep -1G, if you push hard stick it's another story, and of course while engine is idling you lose altitude. So, fuel consumption in the lines are quite nicely modelled and it matters, also G's matters. I forgot to try the reported G4 failure but I dare to say it can be reproduced exactly, using same ATA, same rpm, and probably you get same or close time to engine fail without pumps working. I can only say good work ED.

 

S!

[Siegfried]

Yeah, my test are similar with Manowar ones.

[IIIJG52_Otto_]

Actually Otto and I tested together the feature this evening online, and it was quite better than previously thought (1.2.16 Beta). Inverted flight can be kept by 10-12 seconds with 1.3 ATA (-1G),

then fuel pressure drops and you have a while to level wings and keep flying without further notice. Once levelled fuel pressure rises quite fine and quick (fuel pumps on). With idle throttle I was able to keep some 45 seconds without problem :music_whistling: may be more, then you can see fuel pressure starting to drop but quite slowly so you are plenty of time to level wings and keep flying with no problem at all. Of course again trying to keep -1G, if you push hard stick it's another story, and of course while engine is idling you lose altitude. So, fuel consumption in the lines are quite nicely modelled and it matters, also G's matters. I forgot to try the reported G4 failure but I dare to say it can be reproduced exactly, using same ATA, same rpm, and probably you get same or close time to engine fail without pumps working. I can only say good work ED.

 

 

Yeah, my test are similar with Manowar ones.

 

Yes, it is true, we tested inverted flight after the patch OPENBETA 1.2.16.38601.718, ..but G's negative behavior, i think is not fine yet. :(

[Yo-Yo]

Actually Otto and I tested together the feature this evening online, and it was quite better than previously thought (1.2.16 Beta). Inverted flight can be kept by 10-12 seconds with 1.3 ATA (-1G), then fuel pressure drops and you have a while to level wings and keep flying without further notice. Once levelled fuel pressure rises quite fine and quick (fuel pumps on). With idle throttle I was able to keep some 45 seconds without problem :music_whistling: may be more, then you can see fuel pressure starting to drop but quite slowly so you are plenty of time to level wings and keep flying with no problem at all. Of course again trying to keep -1G, if you push hard stick it's another story, and of course while engine is idling you lose altitude. So, fuel consumption in the lines are quite nicely modelled and it matters, also G's matters. I forgot to try the reported G4 failure but I dare to say it can be reproduced exactly, using same ATA, same rpm, and probably you get same or close time to engine fail without pumps working. I can only say good work ED.

 

S!

 

Thank you, but we have not changed a thing...:)

[Ala13_ManOWar]

Thank you, but we have not changed a thing...:)

I was almost sure, but had no time previously to test it with Otto :lol:. Also I was almost sure those parameters matters so they were testing it the wrong way, pulling excessive G's and not keeping a proper ATA so fuel consumption were too high and inverted fight time too short, so they were producing the engine failure themselves. But had to test myself first :pilotfly:.

 

Anyway, I meant good work to what it's done, I think fuel consumption and how fuel lines behave and interact with instruments are quite a nice work. At least for me, an unknown feature in any flight simulator out there nicely simulated with quite a high detail and complexity :thumbup: .

 

S!

Edited April 8, 2015 by Ala13_ManOWar

[IIIJG52_Otto_]

Thank you, but we have not changed a thing...:)

 

It is true, the bug the remain unrealistic in standard DCS:Bf-104K4 ver. 1.2.16,

Flying inverted at 1.4ATA fuel pressure decreases at 8 seconds, I'm claiming for 34 seconds at 1.4ATA as the Bf-109G of the Rulskilde accident report.

 

Manowar only tested fliying inverted pulling for positive G´s, Not Negative.

[Ala13_ManOWar]

Mate, you don't know the G's I pulled ;) . I was sustaining -1G's for obvious reasons because if you change conditions you get different results, 0G's or -2G's would change it all. And -1G because in mild aerobatics like those in a show usually you are -1G atop of manoeuvres like a loop or barrel roll. Of course and anyway a guess, but you have to keep a standard to test.

 

You cannot claim any "34 seconds" because engines are different hence fuel consumption. And the accident report clearly says "10 second inverted flight", then he levelled so it's not true you have "34 secs inverted flight". The 10 seconds are there right now (-1G of course). So I don't see the problem.

 

S!

Edited April 9, 2015 by Ala13_ManOWar

[IIIJG52_Otto_]

... I don't see the problem.

 

Mate , That is your problem, .. You don´t see diferences. For you, everything is perfect, even in BETA state and unfinished. :music_whistling:

[NineLine]

Mate , That is your problem, .. You don´t see diferences. For you, everything is perfect, even in BETA state and unfinished. :music_whistling:

 

Cool your jets boys and girls... lets not get personal.

[Ala13_ManOWar]

Mate , That is your problem, .. You don´t see diferences. For you, everything is perfect, even in BETA state and unfinished. :music_whistling:

Negative mate, I see differences perfectly. What I don't see nor I want to see are ghosts... :lol:

 

 

The reported G4 accident cannot be reproduced here in DCS, when any pump is disabled, electric or mechanical ones, fuel pressure drops in a while after. So, K model works in a different way than G? G4 report says engine can run without pumps only with gravity and carburettor/injection suction. But also it's not a real G4 but a modern rebuilt... I think I read another threat about the pumps subject, but don't remember conclusions.

 

 

Anyway, I don't see the problem because IMHO fuel lines are nicely modelled, with influence of the fuel flow, engine consumption, G's, pumps... and even if any detail is inaccurate, conclusions told here from a different model than we have, from different engines we have, from different conditions we have, I'm quite sure just can't be used straight in K4 model.

 

S!

[Ala13_ManOWar]

Cool your jets boys and girls... lets not get personal.

No problem Sith, thank you ;). We know in person and it's "normal".

 

S!

[MFG62 Joker]

II'm claiming for 34 seconds at 1.4ATA as the Bf-109G of the Rulskilde accident report.

 

I still don´t see much evidence for 34 seconds. For me the Rulskilde incident has not enough flesh to the bone to deliver more than an educated guess.

[Jamovich]

The solution for flying inverted as long as there is fuel in the tank is a very simple one. A flexible fuel line (the part that goes into the tank) with a heavy clunk at the end. It will always move with gravity (in tandem with whatever fuel there is at any given moment), and this system is used on RC aircraft for time immemorial (my other hobby) and allows for very long inverted flight times.

 

I guess it is not used on full scale aircraft because there is limited use to flying inverted indefinitely as it has no practical use in combat - possibly only in aerobatics

Edited April 30, 2015 by Jamovich