priming warm engine

Forever, Britain's most cherished Crown Jewel
Zacke
Staff Sergeant
Posts: 381
Joined: 27 Sep 2018, 08:18
Location: EDNY

Re: priming warm engine

Post by Zacke »

b. How long should I do this clearing process? 30 sec = starter cycle? Another question: Where does the unburned fuel in the cylinders go to? Is it just pumped to the exhaus system by the movement of the cylinders?

After using the starter for 30 sec how long should it cool down?

User avatar
Killratio
A2A Spitfire Crew Chief
Posts: 5785
Joined: 29 Jul 2008, 23:41
Location: The South West of the large island off the north coast of Tasmania
Contact:

Re: priming warm engine

Post by Killratio »

Generally I would only run the starter for say 10-20 seconds to clear a flood. A wait of 1 minute as per the manual after each cycle but later reduced to 20-30 seconds. Use diuscretion. If this is your second attempt, the starter will cool pretty quickly, if it is your eleventh attempt, not so much! ;)


The fuel is simply pumped into the exhaust stacks, yes (no fuel return valve on a Spitfire). In the real thing a VERY impressive bang and flame can be gained by flooding and clearing. Ground crew not entirely happy!! But hey, these aircraft are old enough to smoke :)
<Sent from my 1988 Sony Walkman with Dolby Noise Reduction and 24" earphone cord extension>


Image

Zacke
Staff Sergeant
Posts: 381
Joined: 27 Sep 2018, 08:18
Location: EDNY

Re: priming warm engine

Post by Zacke »

Did some more testing:

Now I'm sure I flooded her. She seems to be pretty prone to over-prime. When restarting her after some minutes (warm engine) the key is not to touch the primer even if the lines are drained (correct shut down procedure). Just a little bit of throttle and she comes up.

What does the SRCO exactly do? I gues it cut's the ignition for let her come down smooth when she begins to starve fuel.

Another question: Are the primer lines independent of the fuel cocks?

And another strange experience: During my tests I drove the starter for 7 minutes and there wasn't any issue with it. Ok - the whole thing was brand new. But 7 minutes?

Regards,
Zacke

User avatar
Killratio
A2A Spitfire Crew Chief
Posts: 5785
Joined: 29 Jul 2008, 23:41
Location: The South West of the large island off the north coast of Tasmania
Contact:

Re: priming warm engine

Post by Killratio »

The SRCO literally cuts out the "slow running" function of the carby so that the engine stops when it begins to starve of fuel rather than cackling on and draining the lines of fuel almost completely.
The feature was introduced shortly before the Dunkirk (there is debate as to exactly when but certainly by February/March 1940) to enable easier restarting after shutdown and reduced need for priming on restart, thus reducing turn around time in battle.

Yes, the Primer Lines are independent of the main cocks and as such, you can prime the engine before turning on either fuel line. This is a hangover from having a separate priming cock.

Certainly shouldn't be able to use the starter for 7 minutes. A lot of "uncommon" happenings which were originally catered for in the model got lost along the way when the Accusim "core" got updated for addition of P-40, P-51 etc etc.

Unfortunately a lot of that development coincided with me not being around to test the Spitfire...which basically needed to be fully retested, obscure problems and all, with each new aircraft system added to other aircraft.
For example, the changes to the hydraulics model when the P-40 was done completely screwed up the Spitfire's hand pump undercarriage. That needed to be tested, found and put back the way it was by adjusting the size of digital pipes etc!! So things like the starter motor could definitely have been affected when inertia starters and different electrical systems were added. The P-51 electrical system is a lot more robust than the Spitfires and it is possible that the starter motor code is now too "tough" to portray the early Spitfire. I fear that a lot of the "improvements" from the Boultbee Mk IX have also crept into the Spitfire I/II code and don't really represent the early Spits. I know the pneumatic pump needed to be toned right down again to make the pressure more Spitfire I/II ish!

I'll test. But remember, the Spitfire is now a 9 year old aircraft so I would think it is a low priority for updates, even ones that fix what was once there. A sad fact of life.

Basically, when we originally did the Spit, I spent literally hundreds of hours doing exactly what SHOULDN'T be done to make sure that every hamfisted, low IQ, young dumb hotshot, rookie, arrogant moron, idiot pilot error that could be made, suffered the consequences. I cooked more Merlins than Gordon Ramsay has abused assistants. After all these core updates, some of those things have not been able to be tested again.
<Sent from my 1988 Sony Walkman with Dolby Noise Reduction and 24" earphone cord extension>


Image

Zacke
Staff Sergeant
Posts: 381
Joined: 27 Sep 2018, 08:18
Location: EDNY

Re: priming warm engine

Post by Zacke »

Thanks for your explanations and the look behind the scenes.

The Spit is an excellent simulation for me so far. I nurse her and treat her as good as I can concerning the limits. On the other hand I must admit that it makes me a little bit unsecure knowing that some systems aren't modelled as they should originally. I would be very happy if you could test that but I understand very well that we can't expect priority updates for that. Better to know what's going on there. Or better not?

Zacke

Zacke
Staff Sergeant
Posts: 381
Joined: 27 Sep 2018, 08:18
Location: EDNY

Re: priming warm engine

Post by Zacke »

I've flown the Spit now for ten hours or so and had a close eye on the various systems. For me so far everything works as it should - and I'm abolutely fascinated and bonded. But my discovery the starter seems not to wear and your remarks concerning the core updates and the things that could have messed up with the Spit (and are not tested yet) to actually make me feel unsecure. I feel the Spit exactly fits my simulation needs and I wanted to fly her exclusively and for years experiencing her needs and limitations and wear. Do I get that right that I should excpect some modelled systems don't work any more as they are intended to do?

Please don't get me wrong. I don't want to complain. I just want to understand that and handle the circumstances and the given potential of the sim in a positive manner.

Thanks again,
Zacke

Zacke
Staff Sergeant
Posts: 381
Joined: 27 Sep 2018, 08:18
Location: EDNY

Re: priming warm engine

Post by Zacke »

Sorry - one more thougth: It's not so important for me every system works to one-tenth of per cent. But worst case would be systems that are mentioned in the hangar but don't count (wear) because they are "corrupted" by the mentioned core updates. It's a question of balance that produces the feeling of a harmonic system.

User avatar
Killratio
A2A Spitfire Crew Chief
Posts: 5785
Joined: 29 Jul 2008, 23:41
Location: The South West of the large island off the north coast of Tasmania
Contact:

Re: priming warm engine

Post by Killratio »

Zacke,

What I am talking about are the UNUSUAL things people do...like run a starter that is only meant to be run for 30 seconds for 7 minutes straight. The systems all work as they should when operated as they should be. Also, the major things that people do wrong, that break the Spitfire, are all modelled. But If something really outside "normal" is done, then it may not work as intended... nobody in their right mind would run a starter for 7 minutes, so errors like that may have crept in...but if you mess something up that someone would normally mess up, it will bite. All the systems work as they should to damage, wear or look after the aircraft when operated within what a pilot would normally do or the mistakes they would normally make. But the detailed modelling of "bizzare" or "crazy" mistakes may not have carried through all of the updates. A good example of something that is ALWAYS tested is overheating while standing still after startup. That was tested to death on each update.

But can I guarantee that the wheel brakes will overheat if you take off with them half on and then physically seize when they cool, jamming the wheels and flipping you over on landing? No, I can't...because no pilot has ever made that mistake with a Spitfire, no pilot ever would and so it would not be tested....but if you have the brakes overused you may well "run out" of brakes...because that is a mistake that certainly may be made by a pilot.

The only reason I made the comments was to inform you, if you were going to do the kind of "let's do this crazy thing and see what it does" type testing that I did 100s of hours of back in 2010/2011, that you may not get the expected results . If (for example) there is some software flaw that floods the engine if you give 7 instead of 3 primer strokes but starts the engine fine if you have given 123 strokes instead of 3, then 1: it probably hasn't been found and 2: it won't get fixed even if it is there, because no-one would ever use 123 primer strokes.

So operate her within parameters and assume that if you don't you will pay dearly for it...because I assure you that 95% of the time you will!
She is a living breathing beast and you can pretty much rely on her to act realistically in the vast majority of cases.

There are also random things that can break,or not break when they should..just as in real life.

The below posts will give you a good feel of what bad luck, bad decisions, carelessness or lack of adherence to procedures, can buy you.

viewtopic.php?f=77&t=25806&p=196957
viewtopic.php?f=23&t=53124&p=429927
viewtopic.php?f=77&t=54027&p=418554
viewtopic.php?f=77&t=56765&p=439410
<Sent from my 1988 Sony Walkman with Dolby Noise Reduction and 24" earphone cord extension>


Image

Zacke
Staff Sergeant
Posts: 381
Joined: 27 Sep 2018, 08:18
Location: EDNY

Re: priming warm engine

Post by Zacke »

Thanks for your further explanatons and sorry for my anxiety.

Today I took her home from factory (EGHI) to EDNY only using visual navigation dead reckoning (not that easy overflying a cold front over Europe). Went smooth besides the quirks with the ASI. See here: viewtopic.php?p=531464#p531464

Anyway: I love my Spitfire!!!

Just one more word concerning the starter issue. See the following video (start with 4:22): https://www.youtube.com/watch?v=f4mvWzQWtgM. He wrecked almost every item but in the hangar the starter is still green. We don't know what he exactly did but isn't that a further hint s.o. should check that starter simulation? The video is from 2012.

new reply

Return to “Spitfire MkI/II”

Who is online

Users browsing this forum: No registered users and 11 guests