Need to vent

[Decerto]

Landing this plane is hard. Every other plane I can just roll in and flare hard and plop it on the deck, you try that in this one and your a fireball lol.

[Vekkinho]

Reduce Vertical velocity to 1 m/s and you're good!

[Cosmonaut]

You're having problems landing the Tfrog becasue you're probably making the same same mistake most n00bs make. And that is to actually try and land on the runway. All the years I've been flying the 25T and I've never made a successful runway landing, but I figured out that you can land it everywhere else with ease, so now I just look for any flat piece of land and drive it home.

 

Here's a couple of track to demonstrate the easy way to land the Su25T. We Don't Need No Stinking Runway.

25TTRACKS.zip

Edited November 1, 2008 by Cosmonaut

[hitman]

Ok... Corrected drag mathematics for parasitic drag .023 (constant) x 4 (ft) x 220 (spd in kts) = 20.24 lbs of parasitic drag induced by a small whip antenna. Ill ask my instructor tomorrow how much parasitic drag on a low camber, high aspect wing such as the Su-25 would be like. Just think of the 25T as a large glider---just a tad bit heavier for now.

[Ironhand]

Today, for the first time, I saw the image included in your post from the 19th (damn work computer uses an ancient version of IE--I'm viewing from home today). I have to say, if I were an aircraft manufacturer, I would take exception to your description of what you have marked with a yellow band as "Limited Operations". I think they would prefer the term "normal". For that matter, I'd probably take exception to marking it in yellow rather than green or blue.

 

Speaking of "blue", I ran across this image in the FAA Airplane Flying Handbook (FAA-H-8083-3A) in the multi-engine section:

 

 

It's the only image that I've seen showing a blue band in addition to the single blue Vyse tick mark. Unfortunately, the image was simply being used to point out the red Vmc red tick at 80 knots. So it was chary in describing the rest of the dial.

 

I'm also wondering about your description of the white tick mark as "Takeoff speed". As a practical matter, that might be true but every description I've seen of various airspeed indicator markings describes something that's true while you're airborne.

 

I'm searching for Su-25T cockpit images to see if there are any placards describing the various airspeed "hallmarks". Our sim cockpit certainly has no such descriptions.

 

BTW, if any of you are interested, that FAA handbook has a lot of good basic info in it. You can download it from the FAA website: FAA AIRPLANE FLYING HANDBOOK.

 

Rich

[hitman]

The white tick mark (fully loaded and dirty) was decent rotation speed, which was about 300kph. That dial displays just about everything :) 73kts to 125 kts for flaps, 80kts to 105 (Ill read that manual later today) green which looks like max climb speed for 1 engine only, blue range marks for both engines best climb, and limited ops. If I didnt know better, I would say that dial came off of a King Air. I can definitely use that flying handbook for my studies! Thanks Rich...Ill get clarification later today on that dial too. As far as my range markings, I would have shortened my yellow range marking, but it varies at altitude, and I guessed what Vmin was.

Edited July 22, 2008 by hitman_214th

[Ironhand]

The white tick mark (fully loaded and dirty) was decent rotation speed, which was about 300kph.

Like I said, as a practical matter, that is true. I just doubt that that is what that mark is there to indicate. Using it to mark something that happens on the ground would run counter to every other mark or band that appears on an airspeed indicator--to the best of my knowledge, of course. My guess is that it marks either a stall speed or a minimum steady flight speed of some sort--both of which would be something that happen in the air.

 

That dial displays just about everything :) 73kts to 125 kts for flaps, 80kts to 105 (Ill read that manual later today) green which looks like max climb speed for 1 engine only, blue range marks for both engines best climb, and limited ops. If I didnt know better, I would say that dial came off of a King Air. I can definitely use that flying handbook for my studies! Thanks Rich...Ill get clarification later today on that dial too.

The FAA website library provides a wealth of information (and hours of reading material) for anyone interested in flying. Some of the other publications there in PDF format: Pilot Handbook of Aeronautical Knowledge and the Instrument Flying Handbook.

 

 

EDIT: Was able to get a bit of cockpit time today and 300km/hr also happens to be the power-off stall speed (Vso?) for this aircraft in landing configuration at max weight. If the gauge used color bands, then I wonder if this would be the lower limit of the white (flaps operating range) band.

 

Rich

Edited July 22, 2008 by Ironhand
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[Ironhand]

Was playing around with Paint Shop Pro this afternoon:

 

 

 

Not that the placements are actually correct...but I like the look. Makes flying just a bit easier, too.

 

Rich

[LawnDart]

Nice Ironhand...

 

In some of our older military birds (w. steam guages), the mechs paint on the airspeed arcs with paint on the glass of the instrument itself. Helps a great deal to set rpm, and not exceed limitations in combat even when the guage didn't sport any colors in the first place (other than a red line).

[hitman]

Yup...thats my job right there. To provide the pilots with those special colored bands on their sight glasses. Well...I wouldnt willingly do it, but thats the only thing an A&P can do to an avionics instrament other than paint chips in the case.

 

EDIT: Was able to get a bit of cockpit time today and 300km/hr also happens to be the power-off stall speed (Vso?) for this aircraft in landing configuration at max weight. If the gauge used color bands, then I wonder if this would be the lower limit of the white (flaps operating range) band. Ill test that right now.

 

Rich

 

FAA regs prohibit heavy landings...such as if its gross take-off weight exceeds its gross landing weight. I cant be reasonably sure thats what is meant by the white tick mark on the gauge since its CIS (regulations differ from every Aircraft Management Agency), but one thing is definately certain: its there for a reason. Perhaps ED could fill in the blank here?

 

Like I said, as a practical matter, that is true. I just doubt that that is what that mark is there to indicate. Using it to mark something that happens on the ground would run counter to every other mark or band that appears on an airspeed indicator--to the best of my knowledge, of course. My guess is that it marks either a stall speed or a minimum steady flight speed of some sort--both of which would be something that happen in the air.

 

Come to think of it...I always take off (T-Frog, A-10, max take-off weight, ferry, screwing around minimum fuel load, etc...) with full flaps. I still think the white tick mark is R1...it would be almost consistant with all the other CIS aircraft that seem to have rotate around 300kph. There doesnt seem to be any other tick marks in any other CIS aircraft, which is strange to me. I guess I see a cockpit mod coming to an aircraft near you.

Edited July 22, 2008 by hitman_214th

[Ironhand]

:) Unless we can find something definitive regarding that white tick mark.... Whether looked at from your perspective or mine, flight gets very squirrelly at that airspeed. In level flight, clean and light with engines throttled back, you are within a hair's breadth of a stall. (If the air in LOMAC/FC actually "moved", the slightest breeze or a bit of turbulence would induce the stall.) Even with maneuvering flaps extended, you have to be very gentle on the controls in the above situation. Simply lifting the nose a bit will induce the stall.

 

Rich

Edited July 22, 2008 by Ironhand
To make a sentence coherent.

[hitman]

I just asked IguanaKing...he suggested that they are V speed bugs...they are installed on a movable bezel, which actually makes sense because rotate speed, max flaps and Vmin and Vmax speeds are detrimental on air density and aircraft weight/balance...ie you can fly at slower speeds in cold, dry weather than you can in hot, wet weather and the obvious combat payload causing drag and increasing weight on the airframe. It makes perfect sense! :D

[Ironhand]

I just asked IguanaKing...he suggested that they are V speed bugs...they are installed on a movable bezel, which actually makes sense...

:) It does make sense but he simply restates what we already knew about those bugs (tick marks)--they represent V speeds--and added something new (they are probably movable). The question remains. Which V speeds do they represent? There's quite a selection and I've seen longer lists than this:

• 
  Vs
  the aircraft's stall speed in clean, or cruise configuration (gear and flaps up).

 

• Vso
  the aircraft's stall speed in dirty, or landing configuration (gear and flaps down).

 

• Vx
  the airspeed that provides the best angle of climb (highest altitude in shortest distance). It is typically a fairly slow speed, and is most useful for taking off over obstacles like trees.

 

• Vy
  the airspeed that provides the best rate of climb (highest altitude in least time). It is faster than Vx, and is most useful for getting to an altitude as quickly as possible (say, to avoid icing).

 

• Va
  the maximum airspeed for turbulence. For a typical light civilian aircraft, Va will be approximately double Vs, to ensure that the plane will stall under acceleration greater than 0 G (0 m/s²).

 

• Vfe
  maximum airspeed for flap extension.

 

• Vno
  (yellow line) maximum structural cruising speed, to be exceeded only in very calm air.

 

• Vne
  (red line) airspeed not to be exceeded under any circumstances.

 

And some additional V-speeds (multi-engine and other complex aircraft):

 

 

• V1
  critical engine failure recognition speed.

 

• V2
  takeoff speed.

 

• V2min
  minimum takeoff speed.

 

• V3
  flap retraction speed.

 

• Vb
  maximum gust intensity speed.

 

• Vc
  cruise speed.

 

• Vd
  diving speed.

 

• Vh
  maximum level flight speed at full power.

 

• Vlo
  maximum speed for extending the landing gear.

 

• Vmc
  minimum controllable speed with an engine out; any slower and the control surfaces will not be able to counter asymmetric thrust.

 

• Vr
  rotation speed, the speed to start raising the nose during the takeoff run.
  

 

 

Obviously all are not equally possible. But I'm still thinking that the yellow one represents the maximum speed for normal operations (Vno) aka maximum structural cruising speed. And I'm thinking also that the white one marks the aircraft's stall speed in cruise configuration (Vs), since that fits the flight characteristics very well.

 

Rich

Edited July 23, 2008 by Ironhand

[hitman]

I agree we need more clairification on this, but which V speeds would you think one needed most in the cockpit? All this would most likely be located in the flight manual, and alot of this information should be memorized by the pilot. Guess this is why most civilian airliners keep navigators and co-pilots onboard? :)

[Ironhand]

I agree we need more clairification on this, but which V speeds would you think one needed most in the cockpit?

 

Well, I would want to know when I am in danger of falling out of the sky when in landing configuration (Vno), when I can safely maneuver a clean aircraft without worrying about an instant stall, and what top speed can I fly without breaking the airplane while maneuvering in combat. I'd also want to know my flap limitations. Of course, there are a lot of other things I'd want to know, too, but...

 

I guess, in the absence of a bona fide manual, my vote would be that the white marker is either Vs or Vso. I would prefer Vso but, in the sim at least, Vso is around 260 (140 knots). Vs is 300 (162 knots) which is right on the money for what happens in the sim.

 

Based on how the aircraft behaves, the blue marker marks the speed at which you can begin maneuvering without flaps and not worry that you'll stall, if you sneeze. So whatever V abbreviation that might be.

 

I still think that the yellow marker is Vno at 700 km/hr (378 knots). It's the speed you don't want to push beyond unless the air is calm. Or looked at another way, it's the airspeed beyond which you might break the airplane, if you are maneuvering in combat. Interestingly enough, I recall reading somewhere once that the maximum attack speed for the aircraft (real world) is 690 km/hr for that very reason.

 

Of course, all this is speculation but I've done some flying with the altered airspeed indicator:

 

 

and life has gotten much easier. I think the white flaps arc should probably stop at 260. The 500 for the top works OK. At 600 km/hr, you can break the landing flaps if pulling Gs. Not really sure what the real world numbers are for this airplane but marked up as it is above, flying is easier in the sim.

 

Rich

[hitman]

Ill try and get something put together soon...I noticed all the other CIS aircraft need em too. :D

[Ironhand]

Dropped a note to Yo-Yo. While he's not certain, he thinks that the white tick is probably Vs--either that or evolution speed (the speed at which the aircraft will start to fly which is what you were suggesting. He also suggested that the blue marker might be the maximum speed for lowering the gear--he says that it's 390 in real life.

 

Interestingly enough, he thinks that the yellow marker is Vc (optimum or design cruise speed). I did some testing and I'll be damned. Right around that mark is where you get the most for your fuel in terms of distance vs speed. So that's yet another possibility.

 

Rich

[hitman]

Vs sounds credible enough for me...the white tick mark can be used as either Vs or for rotate. Its "technically" the same speed, + or - a few kph not exceeding 10...what is that in terms? Its 3 needles on the dial. Yeah, I think Vs will work. :) Ill wait til Tito gives me his input. Edit: If the range is green, the tick mark should also be green. Will post more follow-ups.

Edited July 24, 2008 by hitman_214th

[hitman]

Well no one seems to know what the flags are for, but I expect them to be rotate/min stall speed, service speed, limited ops and no ops. Ill get working on some mods this weekend, unless theres some late edits...and they can be appended on the fly.

[Ironhand]

Well no one seems to know what the flags are for...

Not all that surprising, I guess. Unless we happened to know someone with cockpit time in that particular bird...

 

...but I expect them to be rotate/min stall speed, service speed, limited ops and no ops.

If stall speed, then it's Vs as Vso is definitely lower. Not sure what you mean by "service speed" but I assume you're referring to the blue mark. Limited ops is yellow? Interesting that it's also your best cruising speed (Vc).

 

FWIW, here's my current version:

 

 

 

I've moved the flaps (arc) a bit and also broadened its width from 350-260 to indicate landing flaps as opposed to maneuvering flaps extension limits. Not sure where I pulled the "350" from as the real world value. I know I read it somewhere. Just not sure where. (In the sim, unfortunately, you're OK with landing flaps up to about 600 km/hr.)

 

EDIT: BTW, I just realized that those markers move individually. Take a look at the sim's Su-25A airspeed indicator. They are bunched together on the ring. So they can indicate just about anything the pilot wants them to.

 

Rich

Edited July 25, 2008 by Ironhand
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[hitman]

By service speed I meant cruise speed.

[Ironhand]

By service speed I meant cruise speed.

OK. So that would be the yellow marker pointing at 700 km/hr? I ask because that is the best cruise speed for this bird both in the sim and, according to Yo-Yo, in real life.

 

Rich

[cobrabase]

Well... took it apart. No wiring problems I think the circuit boards themselves are shot. One button sends a signal down and the circuit board thinks its another button.

 

No more flying for me for at least a year until I can get a replacement.

 

See you all next July.

 

(wishing I was dead)

 

Cobrabase Out.

[hitman]

It will have to be altered slightly (in my mod) from yellow to red. Obviously the aircraft isnt supposed to shake at its best cruise speed, so what I would intend to do is to extend the green arc to 590, start the yellow arc at 590 to 760 (approx. speed shake starts), and red thereafter for expedite speed. Ill have to include a small manual to go with the range markings.

 

What I intend to do is:

White Arc for flap deployment speeds interlaced with Blue Arc for take-off speeds (will work for engine damaged aircraft minimum speeds best rate of climb)

Green Arc for acceptable combat speeds

Yellow Arc for optimal cruise speeds/fuel savings (best range)

Red Arc for expedite (will have to post a G-limit for these speeds)

 

I just have to do some testing to figure out what speed ranges are best for the first 3 ranges. Hopefully ED will model these flags as movable in cockpit sometime in the future. Thats all I have for now.

[hitman]

Well... took it apart. No wiring problems I think the circuit boards themselves are shot. One button sends a signal down and the circuit board thinks its another button.

 

No more flying for me for at least a year until I can get a replacement.

 

See you all next July.

 

(wishing I was dead)

 

Cobrabase Out.

 

Tell you what....Im generous enough, I have money coming my way to get me a new stick. give me a week or so and pop me an address, Ill ship you my old X52. :)

 

It has a lot of hours on it and there are a few quirks, but its only the finger hat switch on the throttle and doesnt like moving to the right. Other than that it just needs to be lubed up and cleaned on the joystick part, nothing serious.

Edited July 25, 2008 by hitman_214th