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Post by Tom Goodrick on Sept 17, 2009 23:27:44 GMT -5
I just got this cute little toy. The model I got is from cavsim on avsim.com - eplxch_4.zip. Don't fly the original because the FD is all screwed up. He has weight at 17,000 lb when it is 10470 lb. He has the wing area at 300 sqft when it is 200 sqft. He has max Mach at 0.78 when it is 0.70. He has thrust at 3200 lbs when it is 1595 lbs. These are only some of the corrections I made. But I am close after only 90 minutes to getting the right performance.
I have two very good articles to use to guide the FD development: FLYING May 2009 and AOPA PILOT June 2009. The latter has good detail on stall speeds, flap settings, flap speeds and gear speeds.
I suspect several more hours work will be needed to get the CG all set and other details. The CG with 80% fuel and two pilots was right at 25%. But when I landed (at nice speeds), the nose gear collapsed when I applied the brake. (It has no spoilers and no reverse thrust.)
The Phenom 100 is a minimal jet with a top Mach of 0.70 which it could only reach in a nearly vertical dive. Its average cruise is 360 KTAS at some altitude over 30,000 ft. It climbs so slowly (350 fpm at 34,000 ft that its ceiling of 41,000 ft is a pipe dream in today's air traffic system.
But it is small and fun to fly.
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Post by Tom Goodrick on Sept 18, 2009 15:15:09 GMT -5
Well, it beats the turboprops but just barely and how practical it will be flying in US airspace is another question. The test flights I read about were made in Brazil where dawdling at FL350 is permitted. in the US you'd be run over every 15 minutes flying at 360 knots at FL350. Then there's the long and slow climb up there. I'd guess this will be flown mostly under FL300 where it's range will suffer a bit. But the range will still be adequate for most people.
My FD now matches all aspects of performance including takeoffs, climbs cruise, maneuvers, stalls and landings. But I did the cruise check last and in doing that I changed the drag quite a bit. This may make more difficult the process of slowing for an approach. We will see. I set the V2 and vref gauges. They show V2 as 122 KIAS at near max gross and Vref as 101 KIAS at MLW. You can cut 10-12 knots off of Vref in a flare for a smooth touchdown. But you will be busy stopping the airplane very soon after touching down.
With no spoilers and no reverse thrust, you have to get the nose down smoothly and start braking with care, especially if the runway is rough as it is at KHSV where I test. I beefed up the nose gear so it does not collapse - hasn't yet after the fix. Obviously, speed control on final is very important.
Flaps are denoted as "flaps 1, flaps 2 and flaps 3." Flaps 1 is 10 degrees and is used for normal takeoff. V2 is calculated for Flaps 1. Flaps 2 is 26 degrees and is an option on takeoff but used more often as an intermediate approach setting. Flaps 3 is 36 degrees and is used strictly on final with about 45% thrust. Vref is set for Flaps 3.
For deceleration, drop Flaps 1 at 200 KIAS which is about normal cruise speed. Then gear goes down at 180 KIAS. At 160 KIAS Flaps 2 can go out but save Flaps 3 for 135 KIAS or below. The nose rises a bit relative to the runway with full flaps. It rides this way nice and steady to just before touchdown when you can flare just slightly before the mains touch.
Here are the stall speeds: Flaps 0 100 KIAS, Flaps 1 94 KIAS, Flaps 2 86 KIAS, Flaps 3 78 KIAS. The first and last values match the data at the specified weights.
Max takeoff weight is 10472 lbs. Max landing weight is 9766 lbs so you have some flying to do between MTOW takeoff and landing. BOW (Basic operating weight including the single pilot) is 7132 lb. Zero Fuel weight is 8444 lbs leaving 1312 as a max cabin load. With this max cabin load you can load 2028 lbs of fuel or 72%. That's a healthy carrying capability. On a jet it seldom makes sense to look at payload with full fuel. On the Phenom you can carry 536 lbs in the cabin with full fuel. That's close to filling three of the five seats. There is a single seat opposite the door and then a four-seat club arrangement with a sizable lav in back.
Camil Valiquette did a great job designing this model. I did not use his panel so I don't see the virtual cockpit and cannot watch the idiot passenger walk back and forth. But if you make shift+C = Wing fold and Shift+D = Tailhook, you can see more action than you get just opening the airstair door with Shift+E. Use Shift+D to open the forward and rear cargo doors. Then tap shift+C and you will see: 1) a limo drive out with your passengers, 2) a cargo tractor back into place at the rear cargo door with the passengers' bags (up to 355 lbs), and 3) a fuel truck drive up to the right wing tip. Tap shift C again and all these things reverse.
The main thing about flying this aircraft is to know the speeds to expect ahead of time and to plan ahead for climb and let-down. Have patience. This is a very low-power operation. It takes a bit to reach V2 and fly off. Then you will see a climb rate of about 1000 fpm for a while as you build airspeed to 200 KIAS. Then you can pull the nose up and zing out of there at 1500 fpm. That's a long way from what a Learjet does. But just think of how much longer admiring people on the ground get to watch you! The pilot reports suggest maintaining 200 KIAS during climb but gradually reducing the climb rate. At FL340 the best you can expect is 350 fpm. My climb to FL350 was slow and challenging but the drag reductions I had to make to get the cruise specs should improve the climb schedule over what I saw. But don't just set the autopilot for climb and walk away. The plane will stall and crash. Most jets that use FL350 start climbing at 4000 fpm and finish at 1000 fpm. This is not your ordinary jet. Coming down will work fine. Just drop Flaps 1, reduce thrust to 10% and maintain 200 KIAS. You'll come down quickly and the pressurization will make it comfortable.
It is interesting that the real aircraft will not let you stall it in any condition. It has a strong stick-pusher that grabs the stick and pushes the nose down whenever a stall is iminent. That tells me the actual full stall is very dangerous. But I left that alone in the FS model. You get a good indication of stall and then you can easily recover.
The CG loading is very simple. I did not check 355 lbs in the aft cargo are which is back quite a way. But normal loads would be two 200 lb pilots with no pax for training and checkout, the one pilot and four pax in back with 40 lbs in the nose and 160 lbs in the rear. I set that up and had 82% fuel for a long trip (HSV to BWI). I think on most flights you will cruise in the 20k's simply because of the tedious nature of the climb. In the AOPA report, it took 34 minutes to reach FL350. That has yet to be checked in the FS model. I took a lot longer but had more drag most of the way up.
It is fun to fly this. But it is not much improvement over the Cessna Mustang, if any. The model looks a lot better.
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Ed Burke
Member
Healthy living is fine, but it's having fun that keeps us going!
Posts: 433
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Post by Ed Burke on Sept 18, 2009 15:34:43 GMT -5
I had trouble with your file name TG, it is ..... ep1xoh_4.zip Any chance of some updated FDs ?
Ed
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Post by Tom Goodrick on Sept 18, 2009 18:03:43 GMT -5
Yes, sorry - eplxoh_4.zip
I'll get a zip together and send it shortly.
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Post by Tom Goodrick on Sept 18, 2009 20:08:50 GMT -5
Before sending Ed his copy of the FD's, I took the Phenom for a spin up to Chattanooga and back. Going up I flew single pilot and returning I had four pax plus bags. On the return I had some trouble slowing down at KHSV. I had to go around. I cruised at 7500 to CHA and 14,500 back to HSV because I had some fuel to burn before landing. Setting up the approach from 7500 ft was rather easy. But coming down from 14,500 ft, I did not allow enough distance. I am used to flying jets with spoilers from that altitude and distance out where you can come down at 3000 fpm. The Phenom does not do so well. It takes a bit more planning to get it right.
Max cruise at FL350 uses 335 pph/eng going 355 KTAS. My cruise at 7500 ft used 373 pph/eng going 252 KTAS and the return at 14,500 ft used 340 pph/eng going 256 KTAS. It can do short trips without breaking the bank but longer trips are certainly best.
I made no changes in the FD's. But I resolve to practice slowing down for the approach.
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Post by Tom Goodrick on Sept 19, 2009 21:35:20 GMT -5
Today I made two small changes in the FD that seemed to help a little. Then I made long flight from KHSV to KHOU and crashed during roll-out on the bumpy runway (30L). The crash was not entirely unexpected. This is the roughest runway in FS9. But it was dissappointing after all other aspects of the flight went well. But it showed me the practical range of this aircraft is 500 nm. That's not good!
I increased the parasite drag scalar from 0.035 to 0.040 to make performance without flaps a little closer to reported performance. It still comes off the runway pretty hot. I increased flap drag by 20% using the drag scalar in the aircraft.cfg file (lift scalar = 1.0). This should help slow down while descending to pattern altitude.
I simulated a flight the NASA transport used to make often. It is nominally 525 nm. You fly direct to Houston, over fly the airport center at about 3000 ft and then break off for a downwind for the designated runway. The pattern is tight as you are in a corner between busy airports. The direct overhead approach keeps you above traffic to Ellington AFB when coming from the northeast. You don't get close enough to Bush intl to get in trouble.
I carried 5 200 lb pax. (180 lb each + 20 lb briefcases on their laps.) This is a typical NASA load. Four of the people are in a working group from Marshall trouble shooting a problem with counterparts at Johnson Space Center. But working stiffs can't justify a custom flight. So a Big Wig rides along to justify the flight. Of course he gets a "cushy" seat in the foresome and the junior engineer gets the jumpseat. So the three woring stiffs say nice things to the Big Wig while trying to prepare for the meeting. sending all the calculations to the guy in the jumpseat who doesn't even have a table for his computer and paper files (if they still use those things).
It looked like we had plenty of fuel (347 gal) for the flight. The CG went to 18% - very far forward. But the plane handled all right. During climb the fuel supply looked pretty lean. The fuel flow is set properly for cruise at 35,000 ft and I use the same amount (about 700 ppm) for all cruising. But in climb I was seeing 2000 pph and the "hours left" was a small decimal amount! At 2000 ft I set 225 KIAS and 2000 fpm climb. At 4000 ft I set 1500 fpm climb. At 10,000 I set 1000 fpm while holding 200 KIAS. I intended to fly at 28,000 ft but changed that to 24,000 ft which we barely made with 135 KIAS climbing at 700 fpm. When level at 54% Throttle and 2X356 pph, the "hours left" showed 2.22 and the GPS showed 1:34 needed. That seemed okay.
Cruise speed was initially 277 KTAS. Later, with no change in throttle, I saw 283 KTAS and 2X 343 pph. Embraer offs a setting on the autopilot that uses autothrottle to hold a constant speed. (As usual I was using altitude hold and either nav or HDG mode.) I see no problem with going a littl faster and using a little less fuel as time goes by in a flight. It is not a big difference.
I wasted a little time by jogging left of course to try going east of Ellington and thencoming in for a direct approach to 30L at HOU. But decided that would probably conflict with traffing into 36 at Ellington. So I correct back to a direct course (about 100 nm out) and made the overhead approach and a circling approach to 30L. On final I noted I only had 47 gallons in the tank as I was pulling out 800 pph using 35% thrust to maintain the ILS with Flaps 3. My "hours left" turned red and showed 0.2. a go-around would have been out of the question.
Before a practical use is seen for this aircraft, I would have to explore many options in flight technique. Now I would say any turboprop like the King Air C90B would beat it in all missions I can think of. Maybe "Lifeline" flight to get a burn patient to a hospital 100 nm away would work, but you'd only get the patient and one EMT in the cabin. Still the C90B might beat it. I understand the cabin is about the same as the C90B, perhaps a bit larget in certain dimensions.
Of course, I will proceed to work on the landing gear so it will roll out at KHOU.
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Post by Tom Goodrick on Sept 20, 2009 8:55:44 GMT -5
OK. Changes were made and two landings were made that went very well. On the main gear I reduced the stroke and increased the damping. On the nose gear I increased the stroke and reduced the damping.
The following landings worked on Runway 30L at KHOU:
95.94 KIAS, -106 fpm 95.45 KIAS, -79 fpm
While there was still some extra smoke as the nose hit some bumps, the aircraft continued to roll out. Braking was reduced during the bumpy portion of the rollout.
Of course, these were made at Flaps 3. There is no other way to land this aircraft. If you used Flaps 2, the touchdown speed would have to be at least 10 knots faster. Getting it stopped then would be a big problem with a likely blown tire.
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Post by Tom Goodrick on Sept 20, 2009 22:04:22 GMT -5
I guess I got it right the first time. This is just a cute little toy. It does not seem to have much practicality. I just compared it to the King Air C90GT on a short flight delivering four state senators from Huntsville to Montgomery, AL. Each pax weighed in at 180 lbs and carried 20 lbs of computer and paper. Plus they were going down for the session so they carried 40 lbs of baggage in back. (Total cabin load 4x(180+20)+120 = 920 lbs.)
The King Air was able to load 1885 lbs of fuel. The Phenom loaded 2420 lbs of fuel.
The 142 nm trip was made directly, cruising at 15,000 ft with an descent that placed the aircraft correctly for a direct approach to runway 28 at KMGM. Both flights followed the plan very closely. The offset was made 50 nm out. With the King Air I had a good feel for its ability to lose altitude without gaining too much speed so I stayed at 15,000 ft until 30 nm out. With the phenom, I started down 40 nm out. Both approaches worked out fine with no wasted flying.
the King Air used 39.64 minutes of flight time. The Phenom used 40.34 minutes of flight time.
The King Air used 347 lbs of fuel. The Phenom used 871 lbs of fuel.
I set cruise on the King Air as I normally would at 75% shp. That gave 251 KTAS and about 270 pph/e. On the Phenom I set power using PPH at about 350 pph. This is the normal cruise power. The speed was about 245 KTAS. Both aircraft climbed to 15,000 ft in about the same time but the Phenom used a whole lot more fuel. It was showing 1500 pph/e during the climb. The King Air showed about half that. Both aircraft held their speed slightly about cruise indicated during the descent. The King Aig Air ended up a bit high but goinh to idle power during a steep turn toward final reduced speed enough to get the flaps and wheels out for a steep descent. Speed and attitude was normal on final for a smooth touch down at 100 KIAS and 120 FPM. The Phenom flew a normal approach working down in speed using Flaps 1 at 200 KIAS, gear 1t 176 KIAS, Flaps 2 at 160 KIAS and Flaps 3 on short final at 130 KIAS for a smooth touchdown at 102.6 and -107 FPM.
The King Air can land at the same weight it takes off at (as all King Airs). The fuel used in climb allowed the Phenom to land directly without having to "waste" fuel. Its weight was 9601 lbs at touchdown. (MLW is 9766 lbs.)
Flying the Phenom is a little more exciting. You have to do the right thing at the right time. Flying the baby King Air is comfortable but it does everything needed with some forgiveness.
Now, you are saying this was a very short flight by jet standards so the cards were stacked toward the turboprop. I bet a longer flight would be worse!
I think the fuel use in the Phenom is correctly modelled. But neither article gives the fuel used to climb to cruise altitude. (Both used 35,000 ft and flew the same route in Brazil.) But their climb rates at the different altitude levels are the same as what I see. In all jet FD developments I have done in FS9, getting the fuel flow right in cruise at altitude gave accurate fuel flow rates during climb and at low altitudes. Absent other engine power constraints, it is safe in a jet to set power according to fuel flow when cruising at non-standard levels. But a POH will often allow higher settings at low altitude to compensate for the reduced speed. In this case that would certainly not help the Phenom beat the King Air! Climbing higher would just burn more fuel. Boosting the thrust would use a lot more fuel than the benefit in speed would be worth.
There may be new things in store for the Phenom 100 to make it more practical. Already there is talk of a Phenom 300. Maybe....
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Post by hanspetter on Sept 29, 2009 16:02:29 GMT -5
I just downloaded the aircraft from Avsim. All I need now is the correct FDs and enough spare time to fly it. Tom, could you please add my email address to the list?
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Post by Tom Goodrick on Sept 29, 2009 18:57:10 GMT -5
It's on the way to you.
When I started looking at flights a little longer than HSV to MGM, I found a number of intriguing places. Perhps the neatest place is Dauphin Island, Alabama. That is an island about 25 nm south of Mobile in the Gulf (but attached to the mainland by a causeway) that has a Marine Biology Laboratory used by professors from Auburn, 'Bama (at Tuscalousa) and the University of Alabama at Huntsville (UAH). My son Scott put in a summer down there wandering the beach studying "marine wildlife." It has a 3000 ft runway (airport 4R9). It is a good place to fly people to and from these three Universities (all parts of the University of Alabama System). I did landing tests there showing that the Phenom 100 and the Beech C90GT can use that runway. But another good one is the Learjet 31Awhich can carry 8 passengers.
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Post by Tom Goodrick on Sept 30, 2009 15:29:06 GMT -5
Here's a cute little flight for the Phenom 100. It is from KHSV to Dauphin Island, Alabama, 4R9. The distance is 271 nm. Cruise altitude was FL280 which it reached with 177 nm to go. Cruise speed was 323 KTAS. We landed after 68.8 minutes. Starting fuel was 346 which brought the weight to MTOW with the payload of 4x200+150lbs and just the single pilot. fuel at landing was 134 gal. But there is no fuel available at 4R9 so I had to fly without payload to KBFM, get fuel and return to be ready for the return trip. When I got to the fuel truck at KBFM I had 88 gal. So you could say I used 258 gal before refuelling. I filled the tanks until there were 392 gallons on board. Then flew back to 4R9. I was ready for the return trip with 337 gallons of fuel. The takeoff would be made at close to MTOW which will be interesting. I'll probably rotate at the water's edge.
Another interesting thing is the change in balance and feel during this flight. Here is the landing data. Note weights and CG.
4R9 107.4 KIAS, -221 fpm, 8980 lb 17.99% BFM 93.92 KIAS, -94 fpm, 7761 lb, 26.74% 4R9 106.7 KIAS, -336 fpm, 9436 lb, 29.88%
For the return flight with the payload the CG will be back near 19%.
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Post by Tom Goodrick on Sept 30, 2009 21:37:54 GMT -5
Here's a good comparison that shows the irrelevance of cruise speed in jet flights. I flew the Beech C90GT from KHSV to 4R9. I cruised at FL280 with a speed of 262 KTAS at 75% shp. It took 70.61 min - less than 2 minutes more than the Phenom 100 that cruised at 323 KTAS at the same altitude. The C90GT started with 297 gallons fuel and used only 82 gallons. It could easily return without refuelling. It carried the same payload - single pilot plus 4x200+150lbs. The landing was uneventful at 105.8 KIAS and -157 fpm with 9546 lb and CG at 29%.
The C90GT used 82 gallons compared to 258 gallons for the Phenom 100 that got there 1.79 minutes faster.
The reason cruise speed mattered so little was climb and descent. The C90GT climbed at a little over 150 KIAS all the way with climb rate starting at 2000 fpm, going to 1600 fpm at 6000 ft, and then going to 1400 fpm at 20,000 ft. When climbing the Phenom 100, I saw 125 KIAS at FL250 because I still was trying to climb at 1000 fpm. I reduced the climb rate to get back to 150 KIAS and avoid stall. Coming down in the Phenom I got down a little farther from the destination and had a few miles longer to cruise at 4,000 ft. The descent in the C90GT was easier to regulate so I quit descending at 2000 ft right near the landing pattern.
Both flights were made in "Fair Weather" which gave a 20 knot wind across the track at cruise altitude.
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Post by Tom Goodrick on Oct 14, 2009 9:17:32 GMT -5
I am doing some tests on the jet engine parameters in FS9. They are the fuel flow gain, the inlet area, fuel flow scalar and the static thrust. I have always set the static thrust according to specs and then left the others alone because I don't know what to do with them. They are not shown in published data on jet engines. Now I am testing the Emb 100 with variations of the fuel flow gain, fuel flow scalar and inlet area. I noticed the inlet area was much larger in the original Emb 100 than on the CitationJet which pulls the same gross weight.
I am trying to improve climb without changing the cruise which is presently correct.
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Post by Tom Goodrick on Oct 15, 2009 9:35:13 GMT -5
I have some test results that are very interesting. First note that from recent work with the Emb 100 on these engine parameters, I changed the parasite drag scalar to 0.65 and left the fuel flow gain at .0022. The fuel flow scalar was reset to 2.0. Then I ran a test in cruise at 30,000 ft where I tried various inlet areas and set the throttle to maintain the same 210 KIAS. Then I noted the fuel flow. Her are the results:
Inlet Area sq ft____%throttle_____fuel flow pph/e
___1.0_____________25__________275 ___2.0_____________50__________276 ___3.0_____________65__________276 ___4.0__no data. could not hold speed. 233 pph max.
I settled at 3.25 sq ft where 70% holds 210 KIAS. This seems to allow the normal range of throttle for all phases of flight and is especially suited to cruise.
I have no idea how this agrees with a fixed static thrust of 1695 lbs. It seems that with a 1 sq ft inlet area the static thrust must increase beyond what is set if you go beyond the 25% throttle. It does not seem to make sense.
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Post by Allen Peterson on Oct 15, 2009 15:40:03 GMT -5
When I was playing around with the VLJs last year I also noticed that the intake area made a difference in the engine thrust. I looked up the engine specs. on the William's site to get the fan diameter and, as a guess, used about 90% of that to calculate the inlet area. I then adjusted the jet_thrust scalar to try to get correct static thrust, measured at sea level, full throttle and with the brakes set.
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