A little more flying quality info on Dino's T-45

[average_joe]

Had a few beers with USMC pilots that flew the T-45 in flight training. I bounced off a few impressions of my flying Dino's T-45. Their responses follow:

1. They confirmed approach speeds in the 120-125 KIAS regime.

2. They confirmed the engine response to throttle movement was slow ... both increasing and decreasing RPM. Dino is close ... I would suggest increasing responsiveness about 10%. Pilots confirmed that one had to anticipate power corrections and give engine time to spool up. Flying with speed brakes out in the landing pattern helped but didn't eliminate the problem.

3. Aircraft response to speed brake deployment not correct in Dino's T-45. Yes the speed brake deployment will cause a rather severe pitch up but that was solved by a speed brake - stabilator interconnect. When speed brake is deployed the stabilator moves automatically to counter any pitchup. There is a slight pitch up ... pilots said maybe a degree of pitch up.

By the way I looked at Dino's .AIR file - the Cm due to spoiler value. It was zero. So I don't know how he modeled speed brake deployment.

4. Top end speed was close to Dino's. When I showed them some acceleration times, the said it was too quick. I would work on the parasite drag value. But as I understand it FSX has overpowered military engines.

5. The airspeed on the HUD seems a bit high for the corresponding Mach on the HUD. I was at 5000' showing 505 knots and .78 M. If 505 Knots is true airspeed the the numbers are close but in that case the HUD should display Indicated airspeed ... in the 470-475 regime.

[neutrino]

Had a few beers with USMC pilots that flew the T-45 in flight training. I bounced off a few impressions of my flying Dino's T-45. Their responses follow:

5. The airspeed on the HUD seems a bit high for the corresponding Mach on the HUD. I was at 5000' showing 505 knots and .78 M. If 505 Knots is true airspeed the the numbers are close but in that case the HUD should display Indicated airspeed ... in the 470-475 regime.

The HUD shows indicated airspeed. At 5,000' and standard atmospheric conditions the KIAS is only a couple of knots different from the true airspeed.

[Sludge]

JR...

I think A J has a point.  Look at this calculator, plug in 5000 ft, 29.92 altimeter, 60 deg F, 475 KIAS.  It comes out to 521 KTAS.

http://www.paragonair.com/public/aircraft/calc_TAS.html

Now the question is, can the HUD be adjusted to display the correct indicated a/speed?  Is that a function of FSX or Im guessing there's a formula to adapt the HUD?

Later
Sludge

[Paddles]

The HUD shows Airspeed indicated variable which is calculated somewhere in FSX, not in FA18_HUD_VC_R.xml
But given a formula, it is possible to change that .xml to show corrected airspeed.

PS. There's also AIRSPEED TRUE CALIBRATE variable (Degrees) - Angle of “True” calibration scale on airspeed indicator. (SDK)

[SpazSinbad]

fsxnavypilot, why not contact Dino Cattaneo yourself. In the past I have pointed out errors to him - for example with his initial Goshawk release (it had the AoA indexer working in reverse) and he was happy to fix this and other issues. If you go here you can see that after the release of JSF-A (which will be fantastic) Dino will work on the Goshawk again:

http://indiafoxtecho.blogspot.com/2010/03/what-after-f-35.html

As you can see I have directed him here already but if you contact him by e-mail then it will be better all round?

dino_cattaneo@libero.it

[average_joe]

One learns more and more by posting on the forum ... safe to say not many of us really knows how FSX runs. Case in point is the airspeed discussion. Given the existence of an Airspeed Indicated variable, it appears that FSX knows to display IAS in a gauge or HUD but the numbers may be off ... maybe FSX uses a loose approximation instead of an exact calculation for simulation speed purposes. I'm sure some of us purists could adapt if we knew.

By the way Dino has done a nice job without much official documentation. Hopefully a post here is a magnet for more input.

War story time ... I was involved in a flight simulator validation project. Real aircrew would fly it and critique the fidelity of it. Was easy to provide subjective comments but in order to tweak parameters we had to jump in the real thing and bring back real data that could be turned into coefficients, etc. ... even with the volumes of flight test data and NATOPS info that already existed. The developers could make changes on the fly. Actually turned out to be a fun project.

The T-45 was supposed to be a simple spin off of the BAE Hawk. Things didn't go well in flight test. (Squadron mate of mine was the chief test pilot on the evaluation). Lots of fixes were required but the Navy didn't want to start with a clean sheet of paper just for a trainer (seems reasonable). They had their hands full at the time with the F-18, the cancelled ATF, V-22, etc.

[Paddles]

One learns more and more by posting on the forum ... safe to say not many of us really knows how FSX runs. Case in point is the airspeed discussion. Given the existence of an Airspeed Indicated variable, it appears that FSX knows to display IAS in a gauge or HUD but the numbers may be off ... maybe FSX uses a loose approximation instead of an exact calculation for simulation speed purposes. I'm sure some of us purists could adapt if we knew.

Well said. Will some of us just check the airspeed numbers with the Hornet?.. For the sake of better understaiding and to make sure that FSX uses a loose approximation for any aircraft... 

[SpazSinbad]

From Legacy Hornet NATOPS here is a weight / speed diagram.

[Stretch32]

I've been watching this and other threads with some interest and thought I'd throw in some info to possibly help with the new Goshawk model. After reading 'Joes first post I can vouch for a few things. I'll have to go through some notes but here's what I can say so far:

1. Approach speed is obviously based on weight and configuration but normally it's between 115 and about 125 (slightly larger window). We calculate it mentally by taking half our fuel weight and adding that to 111 kts for full flaps, 131 for half flaps and 151 for no flaps. An example would be say 2000 lbs fuel and full flaps would equal 121 kts for on-speed. Half of 2000 is 1000 so that's 10 kts added to our base number.

2. Engine response is very sluggish from what we're told and what I've seen. Since I've not flown a Hornet I can't compare the two however you have to be very careful about throttling back to the idle stop and leaving it there for more than a few seconds or the engine will spool down and delay acceleration even further (bad news at the boat and something they harped on very heavily before we went to CQ). This problem is actually worse at higher altitudes due to the thinner air also.

3. The SBI system on the T-45C does alleviate some of the problems of pitch up when deploying speed brakes but it still takes several pounds of forward stick to prevent it (alot of fun when your in parade formation). Also, when retracting the S/B's the nose drops so again, a pull is rerquired to prevent this.

4. The only top speed posted in NATOPS is Mach 1.04 (good luck reaching this though) which is really more like a Vne. I'll have to flip trough some pubs and see if I can't find some better numbers for cruise, climb etc.

Stretch

[SpazSinbad]

T-45A NATOPS weight/airspeed graph. I'll look for the T-45C equivalent graph....

[Stretch32]

Another look through the T-45C NATOPS shows a level flight speed at 30,000' of Mach .85 for a Goshawk. I've personally seen 450 kts IAS at 14,000' at MRT so that might be a good reference number for getting airspeeds for the model in line with the real aircraft.

Generally, we climb out at MRT at 250 kts IAS to 10,000' (intial rate of climb is ~6500 ft per minute) then accelerate to 300 kts IAS the rest of the climb. If we're going high enough we'll actually continue the 300 kt climb to intercept Mach .76 but I've honestly never had to do that (don't generally cruise above 30,000' where it might be an issue although the T-45C can cruise up to 41,000').  

Normal cruise is ~1200lbs/hr on the fuel flow gauge for about 320-330 kts indicated (TAS is alt dependent obviously). The cruise fuel flows are based on altitude to achieve the best ecnomoy and range, the lower you are the higher the required fuel flow and vice versa. Another thing about training command aircraft is that no two seem to fly exactly the same so that might be a consideration. I've flown jets that need 1500 lbs/hr to maintain 250 kts IAS and others that only needed 1200 lbs/hr for 250 kts at our normal training altitudes of 14,000-18,000 ft. Somewhere, I had gouge FF settings for the simulator for various altitudes and the resultant IAS but it's location escapes me at the moment. If I find it I'll post some more numbers that might be of use for getting the model really accurate.

Lastly, I saw some discussion about the T-45C AoA gauge. For on-speed we are at 17 units AoA which is the 3 o'clock position on the gauge. Unit's is an arbitrary measurment calculated to set the proper nose attitude of the aircraft so the tail hook is in an optimum location to catch a wire (obviously is also in the flight regime where the aircraft is easliy controlable at this low airspeed). Early on optimum AoA for on-speed in the Goshawk was set too high and there were some issues catching wires until the problem was identified and the numbers changed because the nose was too low and the hook too high.

Stretch                      

  

[average_joe]

Stretch,

Great input. Maybe Dino will end up with some test pilots for his upgrade! The T-45 (and even the L-159) is a nice little jet for simmers who are just getting into jets. Striving for realism is a good goal but one could take a slightly different approach in this case ... make the T-45 fly like it should have performed for a student pilot ... a more responsive engine for one, reduce the pitch transients from the speed brake (for example the student is supposed to be learning how to fly formation, not fighting the jet), maybe fix some other bad flying qualities.

Stretch ... what did you fly in the fleet? I was a Marine NFO. Been to the boat 700+ times in RF-4Bs, EA-6As, EA-6Bs, F-14As, and a CQ det in the two seat F-18 (trainer version not the "D"). The EA-6A was a lot like the T-45 in that the engines were at such low RPM (we didn't have wing tip speed brakes like the A-6E) that power changes were a challenge ... lots of (actually too many) 1 and 2 wires.

[Stretch32]

Joe,

Just getting started with my career so nowhere near as accomplished or knowledgeable as you or alot of other guys I've seen here (maybe one day though). I've flown T-34C's and T-45C's at this point. Still an SNA but nearly done with Advanced and should finish up here and head to the RAG in June (I'd like Supers or Charlies East, not sure what order though). I've flown the Goshawk for the last year and have a little over 100 hrs or so (not sure exactly, just fly when they say fly). I've also got over 100 hrs in the -45C simulator which is only really good for proceedures and button pushing practice.

As far as modeling the T-45, I do like the idea of making what would be good for the simming community. In all honesty it's so hard to model an aircraft 100% accurately that that may actually be a better route anyway. The T-45 does have it quirks but that's supposedly what makes it a good trainer since Hornets are supposedly easier to fly. We fly something hard so when we get to fleet aircraft the transition is easier I guess. I've actually heard numerous times the Hornet is alot easier to handle around the boat than a Goshawk also (looking forward to that). Can't wait to get auto-trim so the "speed brake drill" is a little less exciting although it's not bad once you figure out how to deal with it 

Stretch 

[SpazSinbad]

Stretch32, Good luck with your training and fleet career. My experience is so long ago it can be difficult to remember finer points (back in 1971-2 with A4Gs on HMAS Melbourne) with far too much shore based work because we had only one carrier (now we have none). Anyway it is always very interesting to me to hear about / find out about Navy jets and how they are in carrier landings or whatever (NATOPS are good often).

Dino Catteneo has now a Goshawk T-45C NATOPS to work with plus material from other sources (mentioned in comments here): http://indiafoxtecho.blogspot.com/2010/03/what-after-f-35.html

https://www.cnatra.navy.mil/pubs/ppub_t45_str.htm (go past 'warning' about certificate)
&
http://www.airwarrior.net/Files.html [AirWarrior has gone on to 'Hairers']  

BTW there was no weight / IAS graph in the T-45C NATOPS PDF I have (bought online). Any chance someone could post these graph(s) please? The previous graph above was for the T-45A and I have no idea what difference might be (if any) for the T-45C. TIA

[Stretch32]

SpazSinbad,

The reason you couldn't find the weight/IAS charts is because they're published in a supplement that is handed out along with NATOPS. I don't have a scanner but if somebody needed some numbers I could send them although you may be able to find this pub in PDF format on the net. The charts basically cover TAS not IAS for a given FF, ALT, Drag Index and weight. There's several charts ranging from 10,000 lbs to 15,000 lbs, altitudes from sea level to 40,000 feet and drag index from 0 (clean) to 150 (loaded for bear). Since these numbers are for a new build aircraft they often aren't completely in-line with what's actually seen. I personally feel the best numbers would be the simulator gouge FF/IAS numbers (I'm still looking for them) that are alot closer to what's really seen flying the aircraft.

Stretch