Crumpp

I have the exact same thing happen. The tutorial and the manual say to open the cowl flaps all the way. I also keep them fully open in a climb. They just do not seem to have any automatic function one you have manually opened them for take off.

BTW, Afterfiring will become an issue if our P-51's get 100/150 grade fuel. The high lead content caused issues with plug fouling. Plug fouling causes misfires which can result in afterfiring. Aircraft engines have two spark plugs (dual ignition) for each cylinder. Fouling one plugs creates conditions that more easily foul the second plug. If both plugs foul, the engine now has a dead cylinder which creates conditions it is easier to foul additional plugs. It can cascade which is why several 8th USAAF P-51's crashed and why such a big deal of it is made by the Technical Branches of both the RAF and the USAAF.

The same way a balloon pops when you release the pressure.

Often the cause in these aggressively cammed piston engines is the valve timing. When you start an aircraft engine, the idea is to ignite the either at TDC (top dead center) or just just past TDC when the piston starts its downstroke. This relieves stress on the engine and starter system and prevents starter kickback. When the engine timing changes to normal logic after the start, the timing is changed to fire just before the piston reaches TDC. This increases the power as the piston then slams into the expanding charge at TDC producing more energy on the power stroke. Our valve overlap is timed to work with normal piston logic. If it is out of adjustment for the starting logic then backfires and afterfires can result. Fouled plugs causing misfiring are also another common cause of afterfiring. Read: https://books.google.com/books?id=SPI6AQAAMAAJ&pg=PA183&lpg=PA183&dq=afterfiring+valve+timing&source=bl&ots=c_jW5ZIjpi&sig=1IOdBi7f-Wj1CauromNLDryAVcU&hl=en&sa=X&ved=0ahUKEwinkPfdz6fJAhWK7CYKHbrOBa8Q6AEIKDAB#v=onepage&q=afterfiring%20valve%20timing&f=false Having fuel detonate in the exhaust is neither normal nor is not harmful. What is normal and not harmful is the acoustics of the collapsing pressure impulse. It is two different things. You do not want DCS to model AFTERFIRING in our engines.

Well then I should get my 790 dollars back for the Franklin engine exhaust manifold I had to buy in 2007.

Listen to this motorcycle with straight pipes. When he backs off you can here the popping from the impulse collapse. [ame] [/ame] Nice loud series of pops......nothing to do with anything being out of adjustment. Just the acoustics of straight exhaust.

Why? Do you think the engine stops at idle? No...it still produces pressure impulses.

Then you know that valve overlapping is the valves remain open. The combustion occurs in the chamber NOT the exhaust system. It exits the exhaust system because the flow is moving that way. If you detonated fuel in your exhaust...you will be replacing gaskets, cracking pipes, or the manifold. Look at the walls of a combustion chamber and look at the thickness of your exhaust pipe. The popping is the pressure impulses collapsing and mixing. It is a normal occurrence in straight exhaust pipes. That is why baffles were invented, btw. You seem to think it is one or the other. That is not correct and you are attempting to invent an argument that does not exist. Both afterfire and the normal acoustics of straight pipes occur. Afterfire is just an indication of something not being correctly adjusted. I have replaced a lot of aircraft exhaust gaskets for this very reason. All it takes is taxing around with the mixture control full rich and the right throttle manipulation. Most commonly seen in the World War inverted and V engines is fresh air inversion. Basically the pipes are so large and short that fresh air gets drawn in after the exhaust impulse. It makes for a lot of popping and does contribute to afterfire because the cam is only optimized for a single rpm and the timing can be off at other rpm bands. In fact most aircraft piston engine starting systems adjust the timing for first few power strokes to occur after TDC to make starting easier. It comes down to popping is good after-firing or backfiring is not. Ask an aircraft mechanic. I learned about all of this when I got my A&P license and a knowledgeable one will tell you the same. If he wanted to clear the plugs he would lean the mixture and run at high rpm for ~30 seconds. I highly doubt the man is not knowledgeable on engines. The engine clearly backfires and he very appropriately shuts it down.

You have the same or even a little better Rate of Turn. That Rate of Turn occurs at a faster airspeed than the Mustang. That means if you try to match the slower speed of the Mustang... He will out-turn you.

Read what I wrote. It does not contradict anything you wrote in your first post. It is a fact that straight exhaust pipes will pop and snap when the throttle is reduced. Listen to any Harley Davidson, car, or motorcycles equipped with straight pipes. There is nothing about some insane throttle closure either. That is one of the reasons why exhaust pipe baffles came to be in existence. Yes it does happen and it is the result of improper adjustment.

It does not cause any harm in any engine. It is just a characteristic of straight exhaust pipes. And watching the film.... I would have shut that engine down immediately just as the operator did! There is something definitely out of adjustment and I would not be surprised if he did not have a gasket or too that needed replacement.

Read what I wrote. It does not contradict anything you wrote in your first post. It is a fact that straight exhaust pipes will pop and snap when the throttle is reduced. Listen to any Harley Davidson, car, or motorcycles equipped with straight pipes. There is nothing about some insane throttle closure either. That is one of the reasons why exhaust pipe baffles came to be in existence. Yes it does happen and it is the result of improper adjustment.

Yo-Yo, Can you tell me the logic and how it works at start up in the Dora. It seems the start up instructions require the pilot to open the gills fully. Is the thermostatic regulator logic being over-ridden right from the beginning in DCS? When does it pick up the automatic function after start?

For the readers: Afterfire is a form of backfire and generally the result of improper adjustments and damaged gaskets. Engines are generally not designed for it and it can damage the motor. Unburnt fuel exploding in the exhaust is not normal or good for an engine despite some myths floating around. An afterfire is a definitely possibility on a hot day when running full rich. That is an improper adjustment of the fuel air mixture and depending on the engine, something should be leaning the mixture whether it is the pilot manually or the automatics in the case of the Merlin. In aircraft engines you see two basic kinds of flames: Low energy flames are present generally at the start up due to excessive fuel. Because of the way aircraft engines are timed for the start, the valves maybe open in the start sequence when spark is delivered igniting fuel. It is not under-pressure and sends out the big dramatic looking flames which can sometimes continue to burn. As long as you keep motoring the engine or achieve a normal start it is not a big deal. Only if you stop motoring the engine and let it burn can it become an issue. The second type are higher pressure flames again due to incomplete combustion and are normal for any internal combustion engine. This is not fuel ignited in the exhaust, it just flames still burning from the combustion cycle getting pushed out of the engine in the normal exhaust cycle. That is normal for any engine but we just do not see them because of longer exhaust systems with baffles found on most internal combustion engines. The short exhaust stacks without baffles found on many large world war II piston engines allows a great view of them! http://www.airliners.net/aviation-forums/tech_ops/read.main/184022/ That exhaust stream is high velocity and high pressure. When you back off the throttle, the pressure and velocity change. Make that pressure gradient large enough and it will create a shock wave as the high pressure collapses into the low pressure causing the popping noise. In a straight exhaust stack, that popping noise is normal and not harmful other than the stresses of rapid throttle changes. It is not the result of improper adjustment, it just a property of that type of exhaust system and one reason why baffles were invented!

Thank you for that thought... :cry: :D

I was hit in that picture...took a few taps from a Bf-109K. I took the screenshot as soon as I noticed it. However, I took off in a fresh Mustang and got the same thing as well as noticed it on another server. Strange....

Yeah.... I hope Yo-Yo was testing it out and that we do get it along with some strategic bomber to escort.

sry Gavangai

Same version Solty. Grrrr This is was not some joke. I got 72inHG all afternoon when I flew the P-51 online on two different servers.

It is this stupid ASUS program AI suite II. It came with the motherboard. There is nothing wrong with the temps but it constantly sounds the alarm. :(

Gavangai, I just tried it offline and online. It is now back to 67inHG.

:megalol:

I engage it several time to check it... 72inHG each time. Maybe Yo-Yo is playing a joke? LOL

It is actually centripetal force being provided by the horizontal lift component but you get the idea.

I am using DCS 1.5 and ran a repair and update before I flew yesterday. Try that Gavagai and see if you get the 72inHG.