Engine startup problem (priming).

[Art-J]

OK, so since a couple of patches ago, I've been wondering why the real-life startup procedure for Mustang doesn't quite work anymore. I'm talking about priming the engine.

 

In the era of 1.2.15-ish it worked like this....

a) booster pump on;

b) priming for 3 seconds;

c) magnetos on;

d) starter on, engine catches, mixture to auto-rich;

... and it was compliant with both real and DCS manual for P-51D.

 

Nowadays, whatever fast mission I create, it works like this...

a) booster pump on;

b) priming for 3 seconds (or any effin' time you want, it doesn't matter anyway);

c) magnetos on;

d) starter on, engine does NOT catch, unless I hit the primer again for exactly 3 seconds. Almost if the previous priming didn't work at all (?). What gives?

 

Now the funny part.

 

Today I decided to investigate the issue again, fired up "Vaziani cold start" instant mission, tried starting up using the "old" method and the engine caught right away. Soooo... then I created a random fast mission on summer map as well, tried the "old" method doing exactly the same thing as previously and... the engine didn't want to start unless I used the "new" method (?!).

 

To completely eliminate human factor, I decided to try both missions again, this time with auto-startup script (which works according to "old" method, with a bit of oil dilution thrown in). Results:

a) Vaziani cold start - engine catches up no problem;

b) any fast mission cold start - engine doesn't start.

 

I'm not an advanced user of full mission editor, so I don't even know how to investigate the Vaziani mission file, but can anyone explain why the historically correct startup procedure works only in this one, while any fast mission in any weather conditions makes procedure useless and forces me to re-prime the engine for no apparent reason?

 

Multiple tests were done in 1.5.2. Same problem in 2.0. Haven't tried auto-script in Nevada cold-start mission, will do it later.

[saburo_cz]

Did you try to rotate propeller, by starter, before priming and without ignition?

3-4 blades are enought for me and I do not any trouble witch engine start.

[Art-J]

No i didn't, 'cause I never had to back in the day, and don't have to now in this particular instant mission. Up to 3 seconds of prime and the engine catches up after 3rd blade every time, whether I do the starting, or computer does. Load it this mission up and see for Yourself.

 

Any other mission, however - I'm unable to replicate this feat even though I do exactly the same thing (computer isn't able either :D).

 

I'm genuinely interested what's going on here.

[Captain Orso]

I've been using the same method since I learned it and have not noticed any difference between 1.2, 1.5, and 2.0.

 

Ram Air to open

Carburetor Heat to normal (default)

Battery to on

Generator to on

Propeller Control to full forward

Throttle to 1" to forward

Fuel Shut-Off Valve to open

Fuel Booster to on

Starter Switch Cover to open

Starter Switch to on (must be held in place)

Count 6 blades

Magnetos (Ignition) to Both

Primer to On (must be held in place)

When the engine catches:

Mixture Control to Run

Release Starter and Primer switches

 

Engine running, take a sip of coffee ;)

 

On Kermit Weeks' Kermie Cam - P 51C Mustang video he pump-primes the engine before turning it over. That may be because the priming is going into the carburetor on the P-51C, where as on the D it's going into the intake manifold.

 

Our manual says NOT to prime the engine while it's not turning:

 

5. PRIMER SWITCH. The Primer switch is used to prime the engine with fuel. The switch is spring-loaded and needs to be held in the ON (up) position to execute a prime. When the primer switch is held ON, fuel passes to the primer lines and into the induction manifold. Usually 3 or 4 seconds are sufficient to prime a cold engine. One second is usually sufficient for a warm engine. The engine should be primed only when it is turning over.

[Art-J]

Nope, not exactly. I know this primer switch description and I'm interested why the DCS manual contradicts itself, as later, in operational procedures it says clearly to prime for 3-4 seconds and switch on magnetos BEFORE any turning over - this fragment of startup instruction was copied from well known real P-51D/K manual anyway, and this is how I was doing it from 1.2.8 (when I got into DCS) until one of the last iterations of 1.2, when something has changed in the code. Watch any of the old youtube vids of players starting up DCS Mustangs - most of them follow the manual and prime only before hitting the starter.

 

Now, I can imagine ED devs changing something to reflect different engine or fuel system version (?) while not updating our manual, as outdated manuals are not uncommon in DCSW universe. That doesn't explain, however, why in the old instant cold start mission the old procedure still works, while in any other mission we have to prime while the engine is turning over. I thought old or new mission files should not affect flight or system modelling of an airplane?

Edited January 6, 2016 by Art-J

[saburo_cz]

Now I uderstand your point, I tested start in mission "cold start.." and engine start was quite easy. When I prepared mission myself, even I set the same weather conditions like in mission "cold start.." (they are not same like in map with default setting) I had to use some more action to start engine.

It looks like that there is some "hidden help" :smilewink: in this prepared (and old) mission.

ED improve its products and it can be one of it (harder and more real start), who knows.

 

btw. I was one of them who here recommended to use priming during start but now i think that it was not right and right procedure is use turn propeller before starting engine start procedure... (which eliminated the needs to priming during start in game but you do not need so many revolutions like is written in original manual, one is enough)

[Mud]

Weird, I'm able to start the engine in 1.5 just lilke I did in 1.2:

 

Ram Air to open

Throttle to 1" to forward

Fuel Booster to on

Magnetos (Ignition) to Both

Fuel Shut-Off Valve to open

Wheel brakes on and locked

Battery to on

Generator to on

Priming for 1-3 seconds

Starter

Mixture Control to Run

[BitMaster]

I have had both truths lately, the cold start like in old days 1-2-GO and the stubborn Merlin of now, which I find far more interesting to start :)

 

Like an ol' Harley, w/o electric starter and black box BS, true iron that needs some muscles and brains or it will not run but kick you off 2 feet high HAHA ;)

[Maulkin]

I fly a Grob 115D in real life and it has a very similar startup procedure to the P-51D in game and I have found that the Grob is *much* easier to start when the engine is cold and than when it is hot. To get around it I have had to give it a bit more throttle than I normally would so instead of a 1/2 inch of throttle I might go as far as a full inch but I would have to be quick to throttle back once I'm sure the engine has caught.

[snowsniper]

in real manual. a writen notes from owner say prime 10 short times.

 

in game: if engine does not start on first attemp, i use this tip : mixture to Run / idlecutof/ run / idlecutof quickly, when I use the starter and then the engine catches

Edited January 7, 2016 by snowsniper

[Art-J]

Weird, I'm able to start the engine in 1.5 just lilke I did in 1.2:

 

Ram Air to open

Throttle to 1" to forward

Fuel Booster to on

Magnetos (Ignition) to Both

Fuel Shut-Off Valve to open

Wheel brakes on and locked

Battery to on

Generator to on

Priming for 1-3 seconds

Starter

Mixture Control to Run

 

Well, in current version one can flip the mixture lever before waiting for the engine to catch on priming fuel only and it will start indeed (though I don't know if it's realistic behaviour, I would suspect engine to be flooded?). But if you want to wait till the engine catches on primer and THEN flip the mixture lever (as per manual), then you can wait till the end of the world, as it ain't going to happen...

 

... unless You start priming again, for exactly 3 seconds, which would probably cause overpriming according to the manual.

 

Funny observation - I opened the aforementioned instant mission in the editor, deleted the "old" player's Mustang and put another "new" one in its place. Didn't change anything else at all. Saved the mission, loaded it up - the "new" Mustang doesn't want to start the old way :D :D :D. I know custom missions can force predefined gameplay options (icons, visibility etc.) but how the hell can they change system modelling of an aircraft - that's one of a hell mystery for me :).

[Mud]

But if you want to wait till the engine catches on primer and THEN flip the mixture lever (as per manual), then you can wait till the end of the world, as it ain't going to happen...

 

That is exactly how I start it (as per manual). However, interesting find you did there though. The missions in which I have been flying were made in 1.2, I made a new one in 1.5 then and ... yup ... no joy.

[Art-J]

Let's hope some Mission Editor expert will hop in and explain why that happens. Who knows, maybe it will be possible to "re-1.2-ize" engine behaviour :D.

[Art-J]

A little update after some flights in 2.0. Looks like it's possible to start the engine the "historical" way in new missions, if only one simulates a "couple of mechs pulling the prop through at least 12 blades", as per real manual. We don't have mechanics in DCS, but before doing anything ignition & fuel related we can turn the engine a bit using starter. After doing it, the 3 sec. priming and startup work flawlessly.

[Body Farm]

Hi Art-J

 

I can concur everything you said about the change in the startup procedure.

 

If I can add a few thoughts:

 

1. Please note that this "historical way" doesn't just work on the cold start mission, but also in the start up training mission.

 

2. I also noticed the change some time in the past when I straggled starting the engine, and also found that you need to turn the propeller before trying to start her up.

 

3. As you mentioned the simulates of a "couple of mechs pulling the prop through at least 12 blades", is according to the RL pilots manual (AAF 51-127-5). But I refer you to the DCS P-51D manual, startup section, page 127:

 

After six propeller blades have passed the canopy, set the Ignition switch to BOTH while continuing to operate the starter.

 

So the DCS manual order is:

a. Prime

b. Operate starter

c. Six blades turn

d. Ignition to BOTH

e. Mixture to RUN

 

The DCS manual does tell us to turn the prop with no ignition before starting her up.

I guess this would be the DCS way to simulate the mechanics turning the prop (as in the RL manual you turn the prop by hand and set the ignition to BOTH before applying the starter).

 

Cheers

Edited January 13, 2016 by Body Farm

[Art-J]

I was never bothered by the ignition aspect, as both methods (flipping the magnetos before cranking or waiting for 6 blades first) have been working both in the old days of 1.2 and now. And since both RL manual and youtube clips of people starting up the real thing would indicate both methods are acceptable, then I'm OK with it.

 

It's the priming part that puzzled me, as it seems that priming pump doesn't work in DCS now (it used to), unless one turns a few blades first. I'm kind of fine with, though. No biggie, just another small thing to do before startup.

[Body Farm]

delete mistake

[Body Farm]

Hey Art-J

 

Sorry to bring up an old thread, but can you (or someone else) test it again on 1.5.4.

 

Did some testing and it looks like it is back to the way it was (the era of 1.2.15-ish, as you called it). On 2.0 the "problem" remains.

 

Can someone confirm this?

 

Thank you

[Art-J]

Hi there. Cannot confirm, 'cause lately I've been getting used to "priming-while-cranking" method, also, I've been affected by infamous 1.5.4 no-trim-bug limiting my DCS enjoyment and playtime anyway.

 

Your note is a good excuse to do some new test runs though :D.

 

Edit - did only one quick startup in 1.5.4 stable, on custom mission to be sure, and indeed, the priming pump operation is back to "normal". That would mean both startup methods are possible again, and that's a nice improvement. Thanks for the heads-up!

Edited July 14, 2016 by Art-J