CT Only: Striker Design Sequence Tables p. 14 Thrust Agency Tables

[snrdg082102]

Hello all,

I'm going through my FFE softcover CT Books 001-008, 0021, and 0022 pulling together a list of ship's vehicles. The Foxhound Atmospheric Fighter in JTAS 14 p. 47 does not have a price that I could find.

From the formatting I believe the Foxhound Atmospheric Fighter was built using CT Striker Design Sequence 11 pp. 42-44.

Looking through the sequence the Thrust Agency Table on Design Sequence Tables p. 14 the basic turboprop and basic turbojet are listed as TL 7 while the high performance versions are listed as TL 6.

My quick research shows that turbojets and turboprops got their beginnings in the 1920's. The turbojet was being used by the Luftwaffe at the end of World War II looking at the Tech Level Chart in CT Starter Charts Book p. 16 appears to be TL 6. There is a picture that shows the British Rolls-Royce RB 50 turboprop on a test stand in March of 1945 which also appears to be TL 6.

Shouldn't the Basic turboprop and Basic turbojet be TL 6 and the high performance version TL 7?

 

[kilemall]

I wouldn't get hung up on the terminology. Looks to me like the TL7 versions are cheaper and/or better performance/fuel ones then the TL6 ones.

IMO should be a TL8 range of increased performance too, have to think another round of materials science would get even better engines in competition with the new gravitics.

 

[snrdg082102]

Hello kilemall,

I wouldn't get hung up on the terminology. Looks to me like the TL7 versions are cheaper and/or better performance/fuel ones then the TL6 ones.

IMO should be a TL8 range of increased performance too, have to think another round of materials science would get even better engines in competition with the new gravitics.

Thank you for the reply. You are right that the type description is something not to get hung-up on. My reason for asking, hopefully not a repeated question, is that the table does not make sense as laid out or appears to match the Traveller TL Description based on the real world development.

My guess, from comments made by aramis earlier in the discussion, is that when Striker Book 3 was being put together the data in the table was the best available corresponding with the TL Description of TL 7.

Back when Striker came out my guess is that the information used for the turboprop, turbojet, and turbofan was from 1970 to 1970 and was the latest the designers had work from which led to the TL 8 Grav Generator taking over.

 

[Piper]

Hi Tom;

I have some hesitation over this, but I think you may be correct that there is a problem.

Looking closely at the chart shows that, in every case, each "high performance" system has higher thrust, fuel use and cost per unit than the corresponding "basic" system. Also, the "high performance" version is available at either the same tech level or one TL higher (propellers). Also note that the turbofan follows this same set of arguments.

It's hard to imagine why a TL6 jet would have more thrust per unit than a TL7 one.

My hesitation comes from two sources. TL7 turbojets are slightly more fuel efficient than the high power, TL6 ones and have a slightly higher thrust/cost ratio. Unfortunately, this doesn't apply to turboprops so this line of reasoning is probably flawed.

The second reason is that Striker did have errata published and one would like to think that an error would have been caught at that time.

Once everyone stops laughing

I realize that multiple errors and "errata for the errata" are all too common. It's possible but frankly, I don't think either one of these cases really holds water.


If you have access to COACC, you might check their tables and see if they can offer up any enlightenment.

 

[kilemall]

I just reviewed the Consolidated CT errata and there is no entry for these systems.

The fuel use you cite is actually what I would expect, the high performance corresponding to military vehicles where economical fuel use is secondary to getting the critical edge in energy-maneuver, and basic corresponding to civilian models where cost efficient buy and fuel use wins the day.

The corresponding comparison would be something like an F-100 jet engine to a 767 engine- the latter may be bigger and more powerful, but the older jet engine would still be producing more thrust per pound since it was a military engine and the 767 won't be pushing Mach 1 anytime soon.

 

[mike wightman]

The 767 won't, but stick that same engine in a lighter airframe designed for supersonic flight and it could.
Modern jet engines are more efficient and more powerful than the Striker designers could allow for at the time.

 

[Piper]

... The fuel use you cite is actually what I would expect, the high performance corresponding to military vehicles where economical fuel use is secondary to getting the critical edge in energy-maneuver, and basic corresponding to civilian models where cost efficient buy and fuel use wins the day.

Yes, thrust to fuel ratio seems to be the only advantage with the TL7 engines being more "refined" while the TL6 engines produce more brute force per unit. It doesn't actually prove that the table is correct, but it does give an argument for it.

Also, for Tom; you probably know this so please forgive me if I'm restating the obvious. TL7 engines do not supersede TL6 ones. You can build a TL8 fighter with TL6 engines (and probably should for maximum thrust).

 

[snrdg082102]

Hello piper, kilemall, Mike Wightman,

Thank you all for providing me with your feedback.

In Reply #4 Piper suggested comparing CT Striker Bk. 3 Thrust Agency Table with the similar table in MT COACC. Luckily one of my uncompleted projects is for MT COACC and I completed the MT COACC Step 3.

The MT COACC table has the basic turboprop and turbojet as TL 6 and the high performance as TL 7. The values for MT Thrust, Fuel, and Price are similar to CT Thrust, Fuel, and cost.

kilemall in Reply #5 confirmed my findings that the Consolidated CT Errata, Striker Errata that came with my set of books, and JTAS 12 Striker Errata p. 40 do not seem to provide information on the high performance turboprop/turbojet being TL 6 and the basic turboprop/turbojet as TL 7.

Mike Wightman's comment in Reply #5 about sticking a 767 engine in a lighter airframe designed for supersonic flight is an interesting idea. Now I wish I had a lot of knowledge in the field. I agree that back in 1981 the stuff in Striker Book 3 was pretty much the best there was.

Now I've, hopefully, getting back to answering Piper's latest reply. Looking at the CT Striker DST Thrust Agency Table the only change to make would be swapping the TL making High Performance turboprops/turbojets TL 7 and the basic versions TL 6. MT COACC's version of the CT table is, as mentioned at the being of my reply, similar with the basic having lower thrust, fuel, and cost than the high performance versions. MT COACC also has a wider range of systems to select form than in CT.

Not a problem about reminding me that the one can build a fighter, or any other vehicle, using different a mixture of TLs. In CT LBB 5 HG2 if I built a TL 14 hull the best sandcaster would be, technically speaking, TL 10.

Again thank-you all for your help.

 

[Piper]

I'm convinced (for whatever that's worth).

Good catch, Tom.

 

[snrdg082102]

Hello again Piper,

I'm convinced (for whatever that's worth).

Good catch, Tom.

Thank you for providing feedback that I appear to have found overlooked errata in Striker.

I may have discovered another bit errata in step 11F of the Striker aircraft design sequence and posted a new topic thread.

 

[kilemall]

The 767 won't, but stick that same engine in a lighter airframe designed for supersonic flight and it could.
Modern jet engines are more efficient and more powerful than the Striker designers could allow for at the time.

Hmmm, facts facts facts.

The key stat is going to be thrust to weight ratio for the engine as a component.

The F-100 engine
https://en.wikipedia.org/wiki/Pratt_&_Whitney_J57

The 767 engine
https://en.wikipedia.org/wiki/Pratt_&_Whitney_PW4000

For point of comparison, the F-22 engine
https://en.wikipedia.org/wiki/Pratt_&_Whitney_F119

Well, basically a progression of 3 to 6 to 9 thrust to weight ratio. That's pretty aggressive compared to the Striker design incrementalism, even if we think of our current TL as 8 in the 1981 definition of the term.

So I knew we were progressing, I just didn't think it was THAT much and we had larger engines and lighter airframes to thank for our performance increases.