Comparison by Spurts

[F-16ADF]

X2, Spurts puts a considerable amount of time/effort into his work.

We should all appreciate that-

[marauder2048]

There is sufficient motivation not to publish everything about a weapon system capability. Spurts gives us insight to what could be possible. In no way is he going to leak secrets just to show off here. The attack on his credibility is absurd considering you offer zero to refute his numbers. Absolutely nothing.

Some of his numbers were sourced from wikipedia.
Some of them seem to be magically generated or nonsensical. Ex: a 4 degree loft angle.
Some of them have minima and maxima that are physically irrational. Ex: the low-end Mach no. for powered flight.

If I've got peer-reviewed, scholarly sources from practitioners in the field, I tend to favor their numbers
especially because they do sensitivity analysis and there's intuition provided.

If others find his approach useful then that's fine.
But he's a bit dogmatic about his numbers and his approach. And the scholarly sources are more comprehensive.

[sprstdlyscottsmn]

I would like to say there is nothing dogmatic or magical about my numbers. I do not choose them with an agenda. I take what values I can from official public information first, anecdotal public information second, Wikipedia as a last resort. For other things I have to take a best guess.

When someone tells me that my numbers are wrong and can provide evidence, as Marauder2048 did, I change my numbers to match the evidence.

Now, marauder2048 has an opinion of me, and my work, that saddens me but I am not going to try and force him to "see it my way" or anything of the sort. They have already shown themselves to be dismissive of my efforts and admittedly does not read my posts to their conclusion where I address my results and the problems therein.

In the end, my take away from this interaction is that I now have better data for the Meteor model, so I am grateful that it happened and I thank marauder2048 for sharing with me.

[garrya]

Some of his numbers were sourced from wikipedia.
Some of them seem to be magically generated or nonsensical. Ex: a 4 degree loft angle.
Some of them have minima and maxima that are physically irrational. Ex: the low-end Mach no. for powered flight.

If I've got peer-reviewed, scholarly sources from practitioners in the field, I tend to favor their numbers
especially because they do sensitivity analysis and there's intuition provided.

If others find his approach useful then that's fine.
But he's a bit dogmatic about his numbers and his approach. And the scholarly sources are more comprehensive.

There is nothing wrong with favoring scholarly sources and there isn't anything wrong with calling out the accuracy of some number if you think they are wrong either. But being aggressive isn't necessary, and name calling isn't helpful for the quality of the discussion.
Keep in mind that we don't actually have any scholarly sources for the whole thing that Spurts is doing right now, which is comparing between Su-35, F-35, F-15EX, F-18E/F, F-16V, Typhoon, Rafale and also their weapons. He also done various scenarios for each aircraft. That is a massive amount of work that he doing ALONE and for FREE so that other enthusiasts like us can have something to enjoy. It is very easy to pick apart some details of a long analysis write up and say you should do this, you should do that. But to actually done the whole analysis ourselves is a whole different story, there is a lot of work to do and it is impossible to not make any mistake
Moreover, it is quite unfair to claim that his numbers are all magical or sourced from Wikipedia. Most of Spurt number involve aircraft are delivered from EM diagrams and flight manual. Then by calculation using well known formular. There is only a few one that he has to borrow from Wikipedia when there is no other choice.
Last but not least, I don't think Spurts is being dogmatic, you are not the first to challenge him about his number or approach. If you read his previous thread, you can see that me and many others challenge him all the time and he always happy to change with new information to make his comparison more accurate.

[garrya]

At that point, 9:1 was a laboratory demonstration. That's where you typically see those high figures.
6:1 or maybe 7.5:1 is what's typically attainable in flight.

What make 9:1 unattainable in flight though? Or what condition of flight that affect throttle ratio but can't be recreated in laboratory

[marauder2048]

At that point, 9:1 was a laboratory demonstration. That's where you typically see those high figures.
6:1 or maybe 7.5:1 is what's typically attainable in flight.

What make 9:1 unattainable in flight though? Or what condition of flight that affect throttle ratio but can't be recreated in laboratory

I explained that above: valve expansion due to heating and accumulation of gas generator products on it.

[garrya]

At that point, 9:1 was a laboratory demonstration. That's where you typically see those high figures.
6:1 or maybe 7.5:1 is what's typically attainable in flight.

What make 9:1 unattainable in flight though? Or what condition of flight that affect throttle ratio but can't be recreated in laboratory

I explained that above: valve expansion due to heating and accumulation of gas generator products on it.

Why can't that be recreated in the lab?

[marauder2048]

Why can't that be recreated in the lab?

Why do we flight test aircraft and munitions?

[marauder2048]

Keep in mind that we don't actually have any scholarly sources for the whole thing that Spurts is doing right now,

Which misses the point: we do have scholarly sources for what he's doing now.
An abundance of them actually.

It's quite easy to find these sources and they completely contradict his modeling on this topic to date.
Which, in my view, makes the other modeling suspect.

Example: He completely misinterpreted Pat Hewitt's dissertation.

[garrya]

Which misses the point: we do have scholarly sources for what he's doing now.
An abundance of them actually.
It's quite easy to find these sources and they completely contradict his modeling on this topic to date.
Which, in my view, makes the other modeling suspect.

We don't have scholarly sources for Meteor itself, only for ramjet missile, though I admit still pretty close. Nevertheless, it is still a very small tiny part of the whole thing he is trying to do and he does the whole thing alone in his free time. So, we can expect that he might miss something along the way, that why I said it is beneficial for the comparison when we contribute our information. But being aggressive is unnecessary and not very helpful, it is like complaining that the youtube sci fi movies made by a single content creator doesn't have the same level of CGI as a Hollywood movie with budget of billions and made by hundreds of people

Example: He completely misinterpreted Pat Hewitt's dissertation.

That dissertation is 118 pages long though

[garrya]

In the end, my take away from this interaction is that I now have better data for the Meteor model, so I am grateful that it happened and I thank marauder2048 for sharing with me.

Btw, this is useful for you:

Their simulated air to air missile is very similar to Meteor

meteor.jpg (32.6 KiB) Viewed 12399 times

[sprstdlyscottsmn]

Thanks garrya! The highlighted boxes and the figures will definitely help. I don't have access to any of my stuff this week so I hope I can get to this over the weekend.

[marauder2048]

We don't have scholarly sources for Meteor itself, only for ramjet missile, though I admit still pretty close.

We do have scholarly sources for VFDR missiles which model a Meteor-like configuration that I posted upthread that you merely regurgitate down thread. They contradict his modeling. That's enough.

Example: He completely misinterpreted Pat Hewitt's dissertation.

That dissertation is 118 pages long though

Which didn't prevent him from almost immediately commenting on it
while managing to completely misunderstand what it's about.

I'd be sympathetic to the page length if there weren't these sections called "abstract" and "introduction"

[garrya]

Thanks garrya! The highlighted boxes and the figures will definitely help. I don't have access to any of my stuff this week so I hope I can get to this over the weekend.

Imho, the specs for Indian indigenous ramjet missile can be used as a rough references point for Meteor.

[sprstdlyscottsmn]

So I was finally able to sit down and update my Meteor model. I used the boost/sustain fuel data from garrya and rewrote my throttle logic to more closely target a set cruise speed (used to be "hold current speed unless we can go full throttle to impact" effectively) within the limits of the throttle (7.5TDR used). I then noticed something troubling. While I had previously modified my thrust model to allow for conditional throttling I had failed to adjust my fuel burn. My model was only allowing a single ISP, which for the Meteor was the Ramrocket ISP of 795. This combined with my boost/sustain transition being time based meant I was only using 1/3 of the boost motor fuel in the boost phase and the rest was being added to the sustain phase.

What an embarrassment.

I fixed that so that the ISP shifts from 265 for boost to 795 for sustain. I also looked up what flight test info I could get for the production Meteor itself.
This yielded a cruising speed of M4+ and engagement range of 60+nm
https://defense-update.com/20130702_gri ... r_aam.html
Launch conditions ranging from .9M 5.5km...
http://www.thenorthspin.com/news08/032008gripen.html
...to M1+ 13km with a flight time of "several minutes"
https://news.cision.com/saab/r/gripen-c ... or,c279439

With better TDR control I was also able to increase loft to 20 and verify that it will not try to exceed a set max altitude while under power.

This results in the "test range" dropping from ~136nm in 300s (and being under power the entire time) to ~81nm in 180s (motor burnout within 40s). For reference, I show the AIM-120D as ~63nm in 180s in my model. I reduced the battery time from 300s to 180s as 180s is still "several minutes" and the similarity of size between the Meteor and the AIM-120 makes it a stretch to assume it has a 67% increase in onboard electrical power. I had only done that initially because at 180s it still had a lot of fuel left due to my errors in ramrocket+booster model.

So thanks again to everyone who provided me data. Missiles and rockets aren't really my thing so it can be hard for me to know when something is close enough.