Instructions for using the X-Plane simulator to fly the CarterCopter


(picture shows CarterCopter's designer, Jay Carter Jnr, trying out the simulator at Oshkosh 2001)

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Runing take-offs

This series of posts is intended to assist those who obtain the X-Plane sim. (Am sure Rusty will keep us updated with any new or modified techniques that emerge)

To do a running take-off you can follow this proceedure :-

  1. start engine - keep throttle at idle & collective at min
  2. engage pre-rotator (depending on your set-up, some configs may require you to hold brakes - ours emulated the CC which locks brakes when pre-rotator is selected)
  3. Turn throttle to full & you should hear rotor spin up (by pressing \ key (on PC keyboard) you can see the CC in front of you on the screen, the left & right arrow keys (PC keyboard) will rotate the CC left and right, press S key (PC keyboard) to return to cockpit view)
  4. When at 350 rotor rpm, release the pre-rotator & CC will automatically increase pitch on prop plus will release brakes & you will blast down the runway
  5. Steer with rudder pedals (or whatever rudder control you have) to aim down runway center line
  6. At approx 60-70mph ease back on stick & if you want extra lift, pull collective slowly at same time (to about 50%). In a good lift off your nose should come up smoothly & the instrument panel top should not go much above the sky at the horizon
  7. Keep the top rim of instrument panel about 1 inch below blue sky on horizon (you really want to get to 70 mph asap - some people fail to monitor their airspeed & rotor rpm)
  8. Retract wheels to reduce drag & gain forward speed
  9. Climb out to about 1500 feet
  10. Once at cruise altitude, ease back to about 2/3 - 1/2 throttle
  11. Adjust collective so that you have between 220-250 rotor rpm (more rpm = greater drag & less forward speed & greater engine power is needed - the goal here is to minimize fuel consumption & avoid using excessive engine power. Too little collective & the rotor rpm will go over 300 & this needs more power from the engine to keep up airspeed.
  12. Don't drop below about 70 mph (certainly keep above 50-60 as it can be difficult to regain speed esp if flying at a low altitudes)


Jump Take-Offs (zero roll take-off)

  1. Start engine - throttle at idle - collective at min
  2. Engage pre-rotator - apply full throttle
  3. At 425 rotor rpm, release pre-rotator
  4. At same time commence steady but swift (not fast) pull on collective up to 100%
  5. Just after commencing the collective pull, move stick forward and slightly to left so that the nose keeps level (if nose pulls up so you see lots of blue sky, you may be pulling collective too fast and/or not applying enough forward stick - if you only see runway you may be pulling collective too slow and/or be pushing stick forward too fast/far). RE left stick, if your nose goes to left of runway, you may be applying too much left stick - the amount left required is actually very subtle but will depend on how fast you pull collective
  6. Keep the top of the instrument panel an inch below blue sky horizon - climb to approx 1500 ft
  7. Slowly reduce collective to about 50% (you can start this from about 400-500 ft)
  8. Retract gear anytime you want (reduces drag & allows faster airspeed build up)
  9. As a general rule DON'T let forward speed drop below about 70mph (certainly keep above 50-60) unless you are coming in for a zero roll landing or at high altitude & experimenting. What is really dangerous is low airspeed and low rotor rpm (as in any gyro).
  10. Rich Kraemer (a CC advisor & former prof of Aeronautics) feels it is ok to start to pull a little collective just prior to releasing the pre-rotator - I am not sure what the impact of this might be on rotational torque forces to the CC but if done carefully should be ok.
  11. Until I got this proceedure right (by day 2 of the show), was pulling collective too fast & going nose up & rolling right. Was also doing these at 550 rpm (takes a bit of time to reach this) - the CC would leap into the sky & within a couple of seconds was at 200-300 feet AGL. On more than one occasion the CC went up so fast it flipped backward & I was able to roll out & recover but usually it was crash & burn (the sim does issue smoke from the CC in a crash). What helped me was then talking other people thru jump take-offs but when it comes to people who over control, it proved quite difficult.

Run-on landings

WORK IN PROGRESS ---- (Land it like a fixed wing (without flaps))


Vertical landings (zero roll landing)

Come in at about 500-750 ft AGL over the end of the runway

You need to be at 70-80 mph or less & with min collective. The trick is to lower engine power (but keep hand on the throttle) & do what ever it takes to spin the rotor up as fast as possible.

As you head down the runway at about 400ft AGL pull back on the stick & go nose up - watch your airspeed closely, use light power & light forward stick if the sink rate becomes too fast or if airspeed slows too much.

Be ready to pull steady collective if you need to slow descent but remember that this slows the rotor and you need as much rotor speed as you can get and keep.

at about 100 ft allow CC to settle - apply light collective to ensure a slow last few feet down. You can hit the deck at up to 20 ft/sec. What ever you do, avoid flying backwards just prior to reaching the runway.

As Rusty Nance has said, you can actually come down vertically from 1000s of feet. At Oshkosh we didn't have time to try that so can't offer advice on how it should be done. We did try lots of vertical landing from low altitude but often we forgot to lower undercart & would bounce & splat. The sim will be fitted with the same warning as the real CC which activates an alarm if wheels are up below a pre-defined airspeed.


Performing rolls

This is fairly easy to do & a little experimenting should help.
  1. Take the CC up to about 3000ft AGL.
  2. Get up to at least 100-110 mph airspeed (with about 50% collective and near full power this should not be hard.
  3. When ready to roll, pull back gently on the stick & when the nose has come up push hard left or right on the stick.

You should be able to achieve double & even triple rolls.


Performing loops

  1. Climb to about 6500 feet
  2. set collective between 40-50%
  3. Apply near max power
  4. Enter a shallow dive of about 1000-1500 feet (down to approx 5000 ft) to get airspeed up to 180-190 mph
  5. when airspeed is up adjust collective down until you have at least 300 rpm on the rotor - you can usually lower collective to min
  6. With a combination of 180-190 mph airspeed and 300+ rotor rpm pull level
  7. When ready, lower collective fully, apply full power, pull back fully on the stick, hold it until the nose is vertical, then slowly pull full collective while balancing the side cyclic - if you do it well the CC won't roll out during the loop
  8. So, all going well you will have looped cleanly. You know you failed if you don't come out of the loop straight.


Flying to mu-1 & beyond

We were able to do this on the sim although the real craft needs modification (underway at present) in order to achieve this.

Firstly - What is Mu-1 - it is the point where the actual CC aircraft's forward speed through the air, is faster that the rotational speed through the air of the tip of the retreating rotor blade. i.e. If the CC is flying at 161 mph & the tip of the retreating blade is flying at 160 mph (approx 100 rpm) then the retreating blade will be experiencing reverse airflow over its full length. For a helicopter, this means the rotor is no longer functioning properly as the retreating blade is supplying no lift.

Mu-1 for the current CC config is 160mph and 100 rotor rpm. Until the CC actually proves it can be done, there are still some people who argue it is imposible even though the CC has wings to take the burden of lift at 160mph. We at CC are quite satisfied it can and is about to be done & the sim also shows it can be done.

At Oshkosh we had the forward speed (on the sim) up to 240 mph with approx 140 rotor rpm. I can't recall if any of us got the rotor rpm down to 100 (actually one person did but it was through a flaw in the sim - he did a rolling take-off without spinning up the rotor & somehow was able to reach 180 mph with 100 rotor rpm).

If the CC can reach 220 mph with the rotor near 100 rpm at sea level, then flying to high altitude means it can easily fly at 400 mph. But to do so needs turbo-chargers for the engine in order to feed enough fuel/air into the manifold.

The reason for it being easy (allowing for the engine being set up to work at the altitude) is that the air is approx 1/5 the density it is at sea level & thus provides less resistance to the craft & rotor. The CC prop is achieveing close to 94% efficiency & is designed for flying fast through less dense air.


Characteristic CC effects (what to expect with CC controls)

Collective:
Collective when pulled will usually cause the nose to pitch up and induce a slight roll to the right, depending on how fast it is pulled.

Pulling collective in flight is similar to doing it on the ground, the CC will jump up - just as on the ground, a bit of forward & slight left stick is needed.

If collective is increased the rotor speed will decay. Flying with about 40-50% collective is normal as this helps keep rotor speed down and thus there is less drag & the prop & engine don't have to work as hard.

Using rotor to slow CC down The rotor can be used as an air brake by dropping the throttle to min, collective to min & pulling back moderately on the stick (nose-up)- this tilts the rotor back and spins it faster but forward speed decays rapidly.

On the simulator this is a reasonable way to comence a vertical descent from about 500 ft AGL just out from end of runway when you want to do a zero roll landing. Dropping collective allows you to speed up & store energy in the rotor - essential if you plan to do a zero roll or near vertical landing.

The classic mistake made by helo pilots on the sim was in forgetting that they can't hover. Several of them came in & got into a hover just above the runway then started flying backwards. They usually lost it at that point.

Cyclic Control Response
The control response will seem very normal to Gyro pilots & quite comfortable for helo pilots. For people who have only flown small fixed wing with yokes & have no stick experience, there was a tendency to over correct (one person looked seriously like he might bend the stick as he was lurching down for a spectacular but predictable crash landing). I couln't do a thing to help him as he was throwing the stick around so violently.

Propellor & Thrust
The prop pitch is computer controlled & this causes it to adjust its pitch based on a number of factors incl airspeed, power setting, engine rpm, etc:.

The CC (both real & sim) can fly inefficiently if the engine power is set to high. There were times when the rate of climb improved noticably by reducing power to about 3/4 or 2/3rds.

Typical Flying Problems
Apart from the mentions of over-control, the other common problems were ignoring important guages and if losing forward airspeed then dropping, also letting the rotor speed get too low when forward speed is 70mph or below. At about 1500 rpm rotor speed and 70 mph, the CC becomes difficult to control & tends to roll around in the sky. This will be further affected by the collective setting.

When the rotor rpm gets low, flapping increases markedly (depending on collective setting). It is not difficult to replicate the conditions Don Farrington experienced last year when the CC was damaged.

There is a known design problem (in the real CC) that shows up on the sim and is being fixed - this is that the inboard wing is stalled & breaks the airflow when the CC drops to about 70mph. This also causes some control difficulty but minor compared to the low rotor rpm control problems.

Stressing the CC & pilot beyond limits
At one point we took the sim CC to 7000 then put it in a vertical dive (we planed to pull out at about 1500 feet), it spun 7 times before experiencing a pilot blackout just as we started to attempt a pull-up.

We also landed on water (to check if it was solid - it wasn't) & the sim treated any water contact as a crash even though on one occasion we did a gentle wheels-up bounce on the water surface and when back in the air found that none of the controls worked any more even though the CC was flying again as anticipated.

The current simulator (ver 6.0 beta)
There is no doubt that the beta version of the CC X-Plane flight sim needs 'tweaking' as it allows the sim CC to do some things the real one can't. Austin Meyer is going to spend some more time refining the accuracy of the sim software. Also, as a result of pilot feedback and that we could replicated it on the sim, there are some mods needed to the CC in order to improve wing AoA at low forward speeds (too much of the inboard wing was spending too much time in stall & thus break air flow to the back part of the CC). Mods to the CC mast position & angle will mean the body is angled forward more than at present, this should improve cockpit visibility & in particular means that the wings are will provide greater control when ailerons are used (with side cyclic).

With the wings angled forward more the real CC should be able to transition lift from the rotor to the wings earlier & allow the rotor rpm to get below 220 rpm at speeds over 140 mph.


General comments on using X-Plane (refers to beta ver 6.0)

While preparing to fly the CC it was really great being able to hit the / key on the PC keyboard so as to see the actual CC sitting in front of you. You can see all the control surfaces move as the pedals & stick are moved. Even collective can be seen on the blades as the collective lever is moved. When the rotor is spinning you also see the disk tilt.

The left & right PC keyboard keys allow you to move left and right around the aircraft image. You can (with some practice) fly the aircraft of your choice in this mode. If selected prior to takeoff, the instrument panel still shows but while in this mode any turns etc: result in the craft rotating in your field of view (in other words you don't remain behind it - a turn left has the aircraft turning such that you then are looking at its side), a 180 turn has the craft facing you (unnerving to some).

When already airborne, you can also hit the / key & if you then hit the A key you will be placed behind the aircraft & will see all control movements as if you are always behind the craft. This is good as you can see the craft move as you move the controls but always from the rear. In this particular mode the instrument panel disappears but again with experience & practice you can fly by the seat of your pants (called good estimating). I found I was able to do jump & roll take-offs plus landings, while in this mode. It takes a bit of familiarity to know what height you are at & speed & rotor speed etc as the gauges aren't there.

The up and down keys on the PC keyboard also allow you to move above or below the aircraft.

It is actually quite interesting flying from behind - the sim allso allows you to set up a HUD (Heads Up Display) - we are not sure if this still allows you to fly in formation with yourself - if so this is a great learning aid.

When we were taking non-flyers through a session we would always switch to the flying behind mode & get them to move the pedals & controls to observe the effect. Most folk were happy to try this but only for a short time.

When in the mode that allows you to see the image of the craft you can return to the normal view by pressing the S key on the PC keyboard.

We never actually got to play with wind strength & direction & conditions - didn't have the time, but X-Plane supports all kinds of weather & even allows download of current weather for particular airports.


THIS SITE = www.internetage.com.au/cartercopters/
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D.Marker email: dmarker@zeta.org.au
R.Anderson email: cartercopter@casagrande.com
- 20 Aug 2001
Created: 20 Aug 2001 - Updated: 20 Aug 2001
Copyright © 2001 Internet Age Pty Ltd