F-16 vs. other teen series fighters in low lvl race..

[n3sk]

F-14–D Has my vote, highest sweep angle of all the teen series and the switch to turbofans.

And I know it’s not teen series but aren’t the Mig-31’s fast down low too? They list 1.25M on wiki.

[That_Engine_Guy]

All anyone in these discussions ever think of is "thrust." How many times have I pointed out the exit velocity of the engines' exhaust also play into 'power'.

KC-135Q was faster than the KC-135R, even though the F108 engiens create 86,536lbs of thrust and the J57s only generated 46,800lbs; so even with double the thrust at low level, the KC-135Q was still refueling the SR-71s at their retirement because the KC-10s and KC-135Es or KC-135Rs weren't as fast.

Same thing can be said of other old turbojets versus their modern turbofan counterparts.

Small-mouth PW powered Vipers can outrun Big-Mouth GE Vipers in specific areas of their respective flight-envelopes; likewise the GEs will take the race from PW in others.

This is what's funny about these 'simulators'; very often the minor differences in the Viper are either not acknowledged at all, or they are grossly under estimated. Simply changing the MIL/MAX thrust levels is the extent of the difference. Are they changing the overall weight of the aircraft? the GE motors have always been heavier. Are they changing the exhaust velocity (specific thrust) of the engines? the PW motors have hotter/faster exhaust. Is the "Big-Mouth" aircraft modeled with the additional drag at high speeds? It does have a larger frontal area.

Don't get me started on realistic fuel-flow rates, based on air density and engine efficiency. (Yes even the age of a motor will affect it's thrust response)

So someone such as myself who KNOWS how these things operate can tell you, racing them in DCS or any other 'imaginary' world is just fun, and not very 'telling'

Keep 'em flyin'
TEG

[sinusoiddelta]

Just want to clarify, there is no F-16 or F-14 flight model currently in DCS World. The video is just a user mod F-14/F-16 with simple flight models. The F-15 in DCS has a “Professional Flight Model” and is surprisingly accurate compared against -220 Appendix B performance charts

[sprstdlyscottsmn]

Thanks TEG.

Having been a DCS user for years, I can tell you that there are vast differences in the modeling of different aircraft. Any pure AI aircraft in the sim is extremely rudimentary, at the time of this video only the F-15 was a player aircraft. The player aircraft have better flight and systems models with a few different levels of fidelity, but they are still simplified. Then come the Study Level aircraft, where having the full FM only gives the developers 5% of what they need. There are very few aircraft in DCS with this level of simulation, the F/A-18C currently in open beta, the A-10C, and the upcoming F-14A/B that will put those two to shame. The only way I would put any credibility into the results of a DCS race would be for a Study Level aircraft where actual operators were consulted during development to ensure everything from systems, handling, to BIT were modeled correctly. Even then, I would say 50/50 chance it was done correctly.

[n3sk]

Teg- but don’t those j57’s take a lot of advantage of “ram air” at high altitude in the cool thin air. The early turbo jets did make more thrust installed at speed then static at sealevel? Or am I confusing things?

Where as the newer engines in most fighters are more efficient lowbypass turbofans, in that they have the mass air in flow, but less gas velocity than a turbo jet.

Which leads me to think a Tomcat on the deck would scoot. the stories I read about the F111 outrunning things, makes me wonder. It’s a shame we sold them to Iran... that was the first nail in their coffin.

Can someone contact DCS and tell them that we need software to simulate jet drag races.

[n3sk]

https://youtu.be/WKA3ITCZt9o this guy claims 1.3m at 100 ft and still accelerating. Around 28:00min in

[That_Engine_Guy]

Teg- but don’t those j57’s take a lot of advantage of “ram air” at high altitude in the cool thin air. The early turbo jets did make more thrust installed at speed then static at sealevel? Or am I confusing things?

Where as the newer engines in most fighters are more efficient lowbypass turbofans, in that they have the mass air in flow, but less gas velocity than a turbo jet.

What you're thinking of is "thrust lapse", and yes, a turbojet is less subject to it because of it's higher specific thrust.

Even 'low-bypass' turbofan engines will have a lower specific thrust and higher thrust lapse than a turbojet.

This is one reason the F110-GE-129 (BPR 0.76) powered Viper will accelerate faster at takeoff than the F100-PW-229 (BPR 0.36) Viper, but at higher altitudes the PW-229 Viper can accelerate better in the thinner air. (The PW-229 has a very low bypass ratio compared to the GE-129 and a slightly higher overall pressure ratio)

The PW-229 has been called a "Leaky Turbojet" in some articles. The 'fan air' adds fresh air into the Augmentor and is used to cool the motor. Pure turbojet afterburners have MUCH higher SFC (Specific Fuel Consumption) than any turbofan because of their lack of fresh air.

Keep 'em flyin' :thumb":
TEG