Flight Question Take off issue with the XR2

[fullarmor2]

I just finished taking off from the runway at Cape Canaveral and I didn't retract the landing gear immediately after lift off. I only waited to do it for a short time and I got the warning right away. I thought I was fine because I didn't think I was moving very fast so I waited. I was less than 1 km in altitude and my IAS hit about 250 mps (about 560 mph). This is when my gear failed and my question is, would 560 mph cause an aircraft's landing gear to fail? I'm not sure thats realistic. Would a commercial aircraft's landing gear fail at 500 mph for example? I kinda doubt it.

 

[garyw]

Would a commercial aircraft's landing gear fail at 500 mph for example? I kinda doubt it.

Yup. considering that cruise speed for a commerical airliner is in the 550-640MPH range. 500MPH would cause the landing gear to slam back so hard that you'd end up with hydraulic leaks and lots of alarms.

500mph = 434knots.

Gear retraction is done around 200knots, often earlier as vr is between 90 and 180knots depending on weight, aircraft type, heat, etc.

A bit more info -> http://forums.jetcareers.com/threads/min-gear-retract-speed.14621/

Next step, a Falcon 10. Vlo 190, Vle 220. Our instructor said, "...don't move the handle above 190, don't fly with the gear down above 220."

 

[insanity]

I just finished taking off from the runway at Cape Canaveral and I didn't retract the landing gear immediately after lift off. I only waited to do it for a short time and I got the warning right away. I thought I was fine because I didn't think I was moving very fast so I waited. I was less than 1 km in altitude and my IAS hit about 250 mps (about 560 mph). This is when my gear failed and my question is, would 560 mph cause an aircraft's landing gear to fail? I'm not sure thats realistic. Would a commercial aircraft's landing gear fail at 500 mph for example? I kinda doubt it.

250 meters/second is the same as going about 486 knots/hour which isn't terribly far from the cruising speed from a 747 (about .8 mach at FL40). In cruise, a 747 with its gears down would create catastrophic failures that would probably lead to a big crash. Doing that speed at ground level with the gear down would be even more damaging (more resistance from the air).

 

[fullarmor2]

Ok. Thanks for the good info.:thumbup:

---------- Post added at 08:48 AM ---------- Previous post was at 08:37 AM ----------

Also as you can probably tell I'm a bit of a novice with Orbiter, although I knew that prompt landing gear retraction is very important at take off. I was just unsure of the whys and hows regarding the topic. So I asked and I'm glad I did. Its quite interesting to learn what the deal is about this, especially since I'm a motivated Orbinaut trainee!

 

[insanity]

If the larger topic of flight is interesting, I'd suggest playing FSX and doing some of the tutorials to get an understanding of the basics of flight.

If you are interested in getting some Orbiter skills, then Go Play in Space is a great place to start.

 

[csanders]

Pulling up to a high pitch (over 45 degrees on the 'surface HUD') right after takeoff helps. You trade speed for altitude, so you don't accelerate as quickly, giving more time to retract the gear.

 

[garyw]

Or you could just set the airspeed to something in the region of 200mph, pull up at 12.5 deg, gear up, turn onto a heading then accelerate.

 

[worir1]

Try throttle back after lift off until you retract the gear

 

[n122vu]

Or you could just set the airspeed to something in the region of 200mph, pull up at 12.5 deg, gear up, turn onto a heading then accelerate.

That's the best advice I've heard so far. It sounds like it came straight from a manual or something.....

 

[Rtyh-12]

Or you could just set the airspeed to something in the region of 200mph, pull up at 12.5 deg, gear up, turn onto a heading then accelerate.

Are you 100% sure of the 200mph figure? 200mph is about 90m/s (a little less), which is very slow for an XR2. Did you perhaps mean 200m/s?

Either way, that's what I do as well; I recommend about 200m/s.

 

[garyw]

Are you 100% sure of the 200mph figure? 200mph is about 90m/s (a little less), which is very slow for an XR2. Did you perhaps mean 200m/s?

Either way, that's what I do as well; I recommend about 200m/s.

200 (metres / second) = 447.387258 mph

So no, I mean around 100m/s to 120m/s. It's more than enough to get you into the air and start a 15 degree turn to intercept the launch heading.

 

[Cras]

On a jetliner, the gear goes up as soon as possible. Once the plane is off the ground, the pilot not flying will watch the vertical speed indicator, and when he sees it signal a positive rate of climb for 2-3 seconds (since you cannot trust a v/s indicator's instantaneous indications, it must be taken over a period of time) he will then call out
'Positive Rate', at which point the pilot flying will call out 'gear up', which then the pilot not flying will raise the gear.

Climb out speeds are often well under 200 knots. More like 170....with a rotation speed around 115-130 knots. Of course the heavier the aircraft, the higher these numbers, but the general profile is get off the runway, cut the throttles back, climb up to 2,000 feet (which is when the aircraft will be put on as full command autopilot as possible) then pitch down so increase speed to climb speed, clean up the flaps on schedule, pitch down again to climb to 240-250 kts (since you cannot fly faster than 250 kts when under 10,000 feet).

The gear provides quite a bit of drag, so you want them up as soon as possible, waiting for any period of time is unwise. Now the limit of gears on jetliners tend to be around 250 kts IAS, which means they can be deployed before the flaps, so when an airplane is coming in on approach with too much energy, the gear can be dropped early to assist with the slowing down of the aircraft, that is a perfectly acceptable thing to do, although you will want to stay on top of your aircraft's speed so you dont have to drop the gear on the downwind....

 

[garyw]

but the general profile is get off the runway, cut the throttles back, climb up to 2,000 feet (which is when the aircraft will be put on as full command autopilot as possible)

My understanding is that the throttles back is more down to noise abatement than anything else.

 

[Cras]

My understanding is that the throttles back is more down to noise abatement than anything else.

There is that as well, but it is a different term.

If you hear the term 'Cut-back', that is the noise abatement.

Otherwise it is just the normal progression from Take Off thrust to Climb thrust, which is always lower. If it is the noise abatement procedure you just go from Take Off Thrust to Cut-back thrust, then back up to Climb thrust (or what ever form of de-rated you have, in Boeing you have TO, TO1, maybe TO2, also assumed temp, but you also have Climb 1, Climb 2...)

 

[Rtyh-12]

200 (metres / second) = 447.387258 mph

So no, I mean around 100m/s to 120m/s. It's more than enough to get you into the air and start a 15 degree turn to intercept the launch heading.

I did some tests about this, and I found that you are at least partly correct. What I did was simply to set the airspeed autopilot to 100m/s, and gradually accelerated from there in 1m/s increments. I found that the XR2 cannot takeoff at 100m/s using aerodynamic control surfaces alone (it can with RCS thrusters). It becomes possible to lift off with aerodynamic control surfaces only at about 115m/s. However, I'm not sure what the practical advantages of this would be, and I think I'll keep using my 200m/s speed.

Still, it's interesting to see the differences between the ascent profile I use and the ones others use

 

[Hielor]

I did some tests about this, and I found that you are at least partly correct. What I did was simply to set the airspeed autopilot to 100m/s, and gradually accelerated from there in 1m/s increments. I found that the XR2 cannot takeoff at 100m/s using aerodynamic control surfaces alone (it can with RCS thrusters). It becomes possible to lift off with aerodynamic control surfaces only at about 115m/s. However, I'm not sure what the practical advantages of this would be, and I think I'll keep using my 200m/s speed.

Still, it's interesting to see the differences between the ascent profile I use and the ones others use

The practical advantages of lifting off at 115 m/s instead of 200m/s are, among others:
- Less fuel used to combat friction with the ground. The sooner you're in the air, the better.
- Less likely to blow up your landing gear. Realistically speaking, the landing gear shouldn't be able to survive rolling along the ground at 200m/s.

 

[769270865]

The airplane rise the gear after postive climb。

 

[statickid]

because the XR-2 has such a powerful engine compared to a regular jet, I get up to V-1 and then throttle down to about 20%, take off, and retract at about 50 meters. Then I turn to my correct heading at a low (low for xr-2), speed to avoid wing stress, pitch up a little and kick the throttle. I climb at about 40-50 degrees to about 15km and begin leveling out and collecting speed for SCRAMs.

 

[Cras]

Or do it this way. I don't need to worry about no stinkin' landing gear with this bad boy.

 

[garyw]

The airplane rise the gear after postive climb。

Not on the XR-2 it won't. On the TX it will. Gear up on the XR-2 is a manual task.