Good points there SE. Fuel quality & quantity can make a big difference in quality of burn. Overly rich due to too large a quanity or poor burn because of too poor a quality, can make for an overabundance of smoke & fire. I'm still in awe when I remember seeing my first & only B52 take off in the 70s. I couldn't see much fire but sure lots of smoke.
Fuel octane was always a problem with the Germans in WWII. Whilst the Allies enjoyed close to 100, the Huns were about 80, not much different than our low grade pump gas today. The DB engines when under full throttle smoked so bad that Allied pilots thought they were damaged so gave up the chase. All the Hun was doing was extending to safe distance & then come back under more favourable conditions.
Anyways, thanks for all the input & I have been known to be wrong sometimes so maybe an education is in store for me, AGAIN!

FWIW,
Good Hunting!

I used to spend a lot of time at RAF Binbrook in the late 70's and had the pleasure of watching the English Electric Lightings spool up and take off. Very little fire except for a blue plume at the initial "fire" then just a heat ripple and hot red close to the exaust. I recall one throwing a turbine blade and the addition of a spark shower made a pretty sight but that was the exception rather than the rule!

That was one of the sweetest aircraft I have ever been around, I miss them dearly.

Ogs.

I'm really glad I started this thread - its turning quite interesting! Thanks for all the factoids guys!

Cool experience Ogdens..

I spent some time around F-4E's at Hahn AB in the late seventies. I remember the black smoke emissions quite well and the noise could be unnerving too. They'd take off in pairs at night sometimes.

The Illinois National Guard used F-4's in the 70's.
I lived close to the airport and we would go watch them takeoff on the weekends.
They always took off in pairs.


Wheels

Random quote from the internets... so it MUST be true!



But that cock and bull about the smoking Hun was funny too

Be nice Hauschild, it doesn't cost any more.
German Fuels
A3-80 Octane
B4-87 Octane
C3-100 Octane

Due to a shortage of C3, DB went to concave pistons to lower the compression so it's engine could run on the lower octane numbers. This limited preignition & detonation within the cylinders on the compression stroke. Even our higher output engines of today with computer controlled timing & fuel mix don't do well on our 87 low grade fuels. I'm not talking about plain jane engines, which most are, but the higher output ones. Because of their higher compression ratios, they smoke & make noises under heavy acceleration. That's why I believed in what I've read about the DBs doing the same thing. The first time I read about this smoke was in James F. Craig's book, The Messerschmitt BF 109. I think he called it a 'sooty black exhaust'. Since then I've read it quit a few times & with my auto repair experience, I did & still believe it.
The bottom line is, overly rich running internal combustion engines give off black smoke. The computers on the vehicles of today, making auto adjustment, stop most of the noise & smoke. In the engines of old, under heavy acceleration, went rich & smoked. With carbs one rplaces jets for mixture whilst with injection, it's an adjutment. Jet or adjust for leaner or richer, altitude being a factor. An air/fuel mixture @ sealevel would not be suficient @ a higher altitude. A clean burn @ the lower would be a richer burn @ the higher. That's why the carb ones would keep adjusting their mixtures for inches of mercury so a more efficent burn would take place. I don't know wether the injection DBs had this abilty. Methinks it was adjusted on the ground, for whatever job was in store, ground attack or bomber busting etc.
Anyways, I've gone long enough. I've found that trying to change attitudes is hopless & it quickly goes into a who's right or wrong rather than what's right or wrong.
Thanks for all the input!

FWIW,
Good Hunting!

These engines didn't have an afterburner.

IIRC correctly, Iowa ANG was still using F-100's in the mid 70's. They'd fly'em into the airshow at Offut AFB.

DB601
Compression ratio: 6.9:1

DB605
Compression ratio: 7.5/7.3:1 with 87-octane fuel; 8.5/8.3:1 with 100-octane fuel

DB603
Compression ratio: 7.5:1 left block, 7.3:1 right block

Merlins had a 6:1 CR and the Allisons were slightly above 6:1.

Don't see no lowering of CRs.

Late war C3 fuel was pushing 140PN.