True Cat A Performance
Thread Starter
Join Date: Apr 2002
Location: Can
Posts: 172
Likes: 0
Received 0 Likes
on
0 Posts
True Cat A Performance
Happy New Year
Just was sitting at work wondering which helicopter types are certified for True Cat A Performance.
By that I mean a helo that is "certified" to take off vertically from a helipad, lose an stove, and either safely reject to the helipad below or safely fly away.
Also it must be "certified" to approach that same helipad, lose a stove on the approach, and either safely fly away or land zero speed (no roll).
Just was sitting at work wondering which helicopter types are certified for True Cat A Performance.
By that I mean a helo that is "certified" to take off vertically from a helipad, lose an stove, and either safely reject to the helipad below or safely fly away.
Also it must be "certified" to approach that same helipad, lose a stove on the approach, and either safely fly away or land zero speed (no roll).
Last edited by Xnr; 1st Jan 2003 at 06:51.
Guest
Posts: n/a
One can argue the real necessity for the capability, but most Part 29 twins have ground level heliport or elevated helideck Cat A procedures, usually as suppliments to the basic RFM. These procedures by definition allow no ground roll. They are generally at considerable reduction in gross weight because the performance penalty for the Cat A landback is severe.
The next generation of helos will meet JAR Ops 3, which will get them much closer to max gross weight with helideck Cat A capability. The S-92 will perform a Cat A takeoff from an elevated helideck with a full passenger load and at zero wind at 35 degrees C with enough gas to fly about 300 NM with IFR reserves.
The next generation of helos will meet JAR Ops 3, which will get them much closer to max gross weight with helideck Cat A capability. The S-92 will perform a Cat A takeoff from an elevated helideck with a full passenger load and at zero wind at 35 degrees C with enough gas to fly about 300 NM with IFR reserves.
Join Date: Apr 2002
Location: canada
Posts: 243
Likes: 0
Received 0 Likes
on
0 Posts
Happy New Year to all!!!
I don't think it's fair to say our present choice of twin powered helo's cannot meet Cat A performance.
I would suggest that the engines alone cannot provide the juice for true Cat A.
Give me an Allison/ Arriel/ Pratt/ or whatever, in my '76, with 1500shp per side and then we'll talk.
Maybe we should be challenging the engine manufacturers instead of the a/c builders????
As a famous man said,
" We need more power Scotty"
J.T Kirk
D.K
I don't think it's fair to say our present choice of twin powered helo's cannot meet Cat A performance.
I would suggest that the engines alone cannot provide the juice for true Cat A.
Give me an Allison/ Arriel/ Pratt/ or whatever, in my '76, with 1500shp per side and then we'll talk.
Maybe we should be challenging the engine manufacturers instead of the a/c builders????
As a famous man said,
" We need more power Scotty"
J.T Kirk
D.K
Sorry, but it's a bit simplistic just to want more pwerful engines. There are a lot of powerplants out there that will produce more than rated power. Generally, the other important limitation is the power that can be transmitted by the main gearbox, particularly when the power input is assymetric: ie, one engine input no power and the other megawatts of it!
So the answer is to build beefier gearboxes, you say. But hang on! The whole darn airframe just got heavier, so we're back where we started.
On a more optimistic note, if a powerplant may deliver more than rated power in a tight spot this may perhaps be at the cost of an engine and gearbox after the successful forced landing. Still less expensive than crumpling the whole aircraft.
Going back to the original point, and reinforcing what Nick says, when aircraft are certificated for Cat A (or equivalent) the test pilots and engineers will develop the best profiles (capable of being flown by an average pilot) for different take-off and landing circumstances and these will be certificated, subject to the associated and defined WAT limits. Stick to the graphs and the profiles and you should be OK. There are quite a few twins around that can operate to CAT A conditions at MAUW from/into restricted areas using the approved techniques on more days than not, in temperate UK-type climates.
So the answer is to build beefier gearboxes, you say. But hang on! The whole darn airframe just got heavier, so we're back where we started.
On a more optimistic note, if a powerplant may deliver more than rated power in a tight spot this may perhaps be at the cost of an engine and gearbox after the successful forced landing. Still less expensive than crumpling the whole aircraft.
Going back to the original point, and reinforcing what Nick says, when aircraft are certificated for Cat A (or equivalent) the test pilots and engineers will develop the best profiles (capable of being flown by an average pilot) for different take-off and landing circumstances and these will be certificated, subject to the associated and defined WAT limits. Stick to the graphs and the profiles and you should be OK. There are quite a few twins around that can operate to CAT A conditions at MAUW from/into restricted areas using the approved techniques on more days than not, in temperate UK-type climates.
Join Date: Apr 2002
Location: canada
Posts: 243
Likes: 0
Received 0 Likes
on
0 Posts
simplistic!
Nick L. and Idle Stop,
Yes, I was intentionally being simplistic!
Twin a/c we have are good strong machines. Designed well and tested extensively.
It's very easy to find the weak links in the machine if we just concentrate on specific performance criteria...ie.. perfect Cat A flight at all flight envelopes and weights.
Sure, you guys can put extremely powerful engines in the a/c, but at what cost?...... no payload and minimum fuel!!
However, I do see a time when some 12year old, Playstation addicted, geeky kid, turns out to design lighter, more powerful, smaller engines.
You guys, as engineers, must acknowledge that is possible in the future.
Yes, I was intentionally being simplistic!
Twin a/c we have are good strong machines. Designed well and tested extensively.
It's very easy to find the weak links in the machine if we just concentrate on specific performance criteria...ie.. perfect Cat A flight at all flight envelopes and weights.
Sure, you guys can put extremely powerful engines in the a/c, but at what cost?...... no payload and minimum fuel!!
However, I do see a time when some 12year old, Playstation addicted, geeky kid, turns out to design lighter, more powerful, smaller engines.
You guys, as engineers, must acknowledge that is possible in the future.
The other consideration when looking at more powerful engines is that when in twin mode they will be a long way off their design point and consequently very inefficient. The result is horrendous fuel consumption. Look at the 76-B (sorry Nick, no offence!). In some areas that isn't a problem, but it certainly is in others.
212man......
Must be the EC-155 you drive must fit your description of the perfect machine....engines that get the best fuel consumption on two.....although probably not the best on one donk. How long is your takeoff distance required now....still on the order of 1700 feet for the Shell Machines?
Must be the EC-155 you drive must fit your description of the perfect machine....engines that get the best fuel consumption on two.....although probably not the best on one donk. How long is your takeoff distance required now....still on the order of 1700 feet for the Shell Machines?
Who cares really?
When was the last time anyone needed Cat A performance?
Solution to perceived problem: new engines with enhanced durability and reliability. We are flying the sky with 1960's engine design.
When was the last time anyone needed Cat A performance?
Solution to perceived problem: new engines with enhanced durability and reliability. We are flying the sky with 1960's engine design.
Join Date: Nov 2002
Location: home
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
Regarding new engines....
I read a realy interesting article in Flying magazine the other day.
One of it's contributing writers was going on about the Eclipse and how the project wont work because the project is based on the design of brand new engines. The writer concludes that the design wont work, hence the aircraft will never fly.
I for one hope that the company will provide it's new engine with all the capabilities it promises. It's time engine makers take a step into the future and start making smaller, lighter and better engines.
Idiots like the writer in the article that think it will never happen, should realize that a 100 years ago we weren't even flying and that it's always up to some pioneers to raise the bar.
If the new engine design works, you know every manufacturer will start making a similar model, but now it's easier for them to say it's impossible to make one and just keep on selling the same old 1960's stuff.
Just my opinion though, I could be wrong.
Jack S.
I read a realy interesting article in Flying magazine the other day.
One of it's contributing writers was going on about the Eclipse and how the project wont work because the project is based on the design of brand new engines. The writer concludes that the design wont work, hence the aircraft will never fly.
I for one hope that the company will provide it's new engine with all the capabilities it promises. It's time engine makers take a step into the future and start making smaller, lighter and better engines.
Idiots like the writer in the article that think it will never happen, should realize that a 100 years ago we weren't even flying and that it's always up to some pioneers to raise the bar.
If the new engine design works, you know every manufacturer will start making a similar model, but now it's easier for them to say it's impossible to make one and just keep on selling the same old 1960's stuff.
Just my opinion though, I could be wrong.
Jack S.
Thread Starter
Join Date: Apr 2002
Location: Can
Posts: 172
Likes: 0
Received 0 Likes
on
0 Posts
Steve76
The problem comes when our "friends" at Transport Canada restrict helipads to machines capable Cat A performance.
Can you legally land there with the machine you fly at the weight you carry?
The effect of this restriction is severe and most cannot comply.
The problem comes when our "friends" at Transport Canada restrict helipads to machines capable Cat A performance.
Can you legally land there with the machine you fly at the weight you carry?
The effect of this restriction is severe and most cannot comply.
Last edited by Xnr; 2nd Jan 2003 at 15:53.
There are no limits
New does not necessarily mean better reliability or durability. Have flown around 2000 hours in various machines with the RR/Allison 250 and never had a failure, but a few precautionary shutdowns for Chips.
Steve76
Do you mean Cat A performance OEI or AEO? If you are doing HEMS then you often need the AEO performance for helipad (elevated) and sub-helipad (exemption) approaches and departures.
Shouldn't we really be talking Cat I, II, III ?
Can of worms opened.......
Steve76
Do you mean Cat A performance OEI or AEO? If you are doing HEMS then you often need the AEO performance for helipad (elevated) and sub-helipad (exemption) approaches and departures.
Shouldn't we really be talking Cat I, II, III ?
Can of worms opened.......
Join Date: Nov 2002
Location: home
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
Xnr,
why do you consider the requirement for a 'true cat A' from TC as a problem?
Wouldn't it be nice if you could fly a slightly more potent machine, thus increasing the safety aspect?
I understand it would be hard for any company to upgrade an entire fleet, but I think it will be just a matter of time before TC starts following JAR Op's and starts imposing higher limits.
Yes it will lead to a lot of complaining, but I'm sure the crews actually flying the machines will feel pretty good about it.
Flying to an elevated rooftop less than 100' square, in an A model at +30C weather with 5 on board, some cargo and fuel is just not as safe as it should be. Now you can train all you want for the 'unlikely event' of an engine failure in these conditions, but know that the day an engine quits on the final stage of your approach to a pad in such conditions, you better be right on the numbers, as there will be no margin of error.
Of course some of the aviation gods will dispute this because this will A: never happen to them and B: they can deal with such emergencies at any time.
Of course that's just my opinion, I could be wrong.
why do you consider the requirement for a 'true cat A' from TC as a problem?
Wouldn't it be nice if you could fly a slightly more potent machine, thus increasing the safety aspect?
I understand it would be hard for any company to upgrade an entire fleet, but I think it will be just a matter of time before TC starts following JAR Op's and starts imposing higher limits.
Yes it will lead to a lot of complaining, but I'm sure the crews actually flying the machines will feel pretty good about it.
Flying to an elevated rooftop less than 100' square, in an A model at +30C weather with 5 on board, some cargo and fuel is just not as safe as it should be. Now you can train all you want for the 'unlikely event' of an engine failure in these conditions, but know that the day an engine quits on the final stage of your approach to a pad in such conditions, you better be right on the numbers, as there will be no margin of error.
Of course some of the aviation gods will dispute this because this will A: never happen to them and B: they can deal with such emergencies at any time.
Of course that's just my opinion, I could be wrong.
Join Date: Dec 2001
Location: Philadelphia PA
Age: 74
Posts: 1,835
Likes: 0
Received 2 Likes
on
2 Posts
xnr:
I think I know a bit of the background to this problem as I used to work in TC Aircraft Certification and discussed this a lot with the ops people, and the heliport design folks.
The issue was safe operation in and out of some heliports that weren't ideal. The solution was to either require Cat A, or demonstrated performance to get you into or out of the heliport if an engine failed.
This was the first time that TC had required Cat A in any operations, so I'm not surprised that there were some questions and comments.
But it was done with a lot of discussion and consideration. Any other problems, you can contact me off-line if you want.
I think I know a bit of the background to this problem as I used to work in TC Aircraft Certification and discussed this a lot with the ops people, and the heliport design folks.
The issue was safe operation in and out of some heliports that weren't ideal. The solution was to either require Cat A, or demonstrated performance to get you into or out of the heliport if an engine failed.
This was the first time that TC had required Cat A in any operations, so I'm not surprised that there were some questions and comments.
But it was done with a lot of discussion and consideration. Any other problems, you can contact me off-line if you want.
Guest
Posts: n/a
Jack S,
The issues that determine the mix of airframe properties are not as simply stated as "Do you want Cat A or don't you". Given a free choice, I'd take Cat A from cradle to grave, fuel for 1500 NM, and a blonde copilot, thanks. Life, and helicopter design, don't work that way, unfortunately.
The basic problen is that you ask a loaded question - "why do you consider the requirement for a 'true cat A' from TC as a problem? " This question assumes that you just check off a property and it is delivered to you, like Amazon.com without a charge. Not so.
How about if you ask the question the way a designer sees it?
"Which would you rather have, hover to hover Cat A, or a helicopter that costs 10% less?" Or "Which would you rather have, hover to hover Cat A, or a helicopter with 50 NM more range" Or "Which would you rather have, hover to hover Cat A, or a helicopter with full GPS coupled autopilot to a hover"
The cost of taking a regular Cat A twin helicopter to a zero ground roll on a single engine is very real, and not easily hidden. Basically, the second engine is along for the ride, mostly. For a 10,000 pound twin, I would guess the weight penalty would be about 300 pounds of empty weight ("Which would you rather have, hover to hover Cat A, or an extra fare-paying passenger?"). The cost of engine power is the steepest bill we pay, withg the engine, the transmission, shafting and fuel all tolling up bigtime. It would be hard to imagine the cost of the hover to hover Cat A being less than 10% of the purchase price of the aircraft.
All this also must be weighed against the need, since we have lots of data to show that the few seconds of exposure during takeoff and landing are almost insignificant in terms of measurable safety improvement. ("Which would you rather have, hover to hover Cat A, or a full enhanced ground proximity warning device?")
The issues that determine the mix of airframe properties are not as simply stated as "Do you want Cat A or don't you". Given a free choice, I'd take Cat A from cradle to grave, fuel for 1500 NM, and a blonde copilot, thanks. Life, and helicopter design, don't work that way, unfortunately.
The basic problen is that you ask a loaded question - "why do you consider the requirement for a 'true cat A' from TC as a problem? " This question assumes that you just check off a property and it is delivered to you, like Amazon.com without a charge. Not so.
How about if you ask the question the way a designer sees it?
"Which would you rather have, hover to hover Cat A, or a helicopter that costs 10% less?" Or "Which would you rather have, hover to hover Cat A, or a helicopter with 50 NM more range" Or "Which would you rather have, hover to hover Cat A, or a helicopter with full GPS coupled autopilot to a hover"
The cost of taking a regular Cat A twin helicopter to a zero ground roll on a single engine is very real, and not easily hidden. Basically, the second engine is along for the ride, mostly. For a 10,000 pound twin, I would guess the weight penalty would be about 300 pounds of empty weight ("Which would you rather have, hover to hover Cat A, or an extra fare-paying passenger?"). The cost of engine power is the steepest bill we pay, withg the engine, the transmission, shafting and fuel all tolling up bigtime. It would be hard to imagine the cost of the hover to hover Cat A being less than 10% of the purchase price of the aircraft.
All this also must be weighed against the need, since we have lots of data to show that the few seconds of exposure during takeoff and landing are almost insignificant in terms of measurable safety improvement. ("Which would you rather have, hover to hover Cat A, or a full enhanced ground proximity warning device?")
Nick,
In yer opening you suggest a liberal leftist "cradle to grave" Cat A welfare system....but then digress to suggest a more conservative "cost vs risk " scenario. Perhaps you are hanging around the oil company management types a bit too much? If you see the advantage of the full Cat A, much as the S-92 will provide (per your earlier post), why the contrary statements. I know you will hit me up with the 0.0000008 chance of an engine failure number....as in earlier posts....but why remind us of the wonderful improvement in performance the 92 brings over previous designs if that in fact becomes an expensive overkill situation for commercial operators? Per chance, you Sikorsky types are really designing a new airframe for military applications and will do a transfer of technology bit at some time in the near future and provide the Coast Guard or some other operation an improved airframe for their mission?
In yer opening you suggest a liberal leftist "cradle to grave" Cat A welfare system....but then digress to suggest a more conservative "cost vs risk " scenario. Perhaps you are hanging around the oil company management types a bit too much? If you see the advantage of the full Cat A, much as the S-92 will provide (per your earlier post), why the contrary statements. I know you will hit me up with the 0.0000008 chance of an engine failure number....as in earlier posts....but why remind us of the wonderful improvement in performance the 92 brings over previous designs if that in fact becomes an expensive overkill situation for commercial operators? Per chance, you Sikorsky types are really designing a new airframe for military applications and will do a transfer of technology bit at some time in the near future and provide the Coast Guard or some other operation an improved airframe for their mission?
Thread Starter
Join Date: Apr 2002
Location: Can
Posts: 172
Likes: 0
Received 0 Likes
on
0 Posts
Sorry boys...I have to agree with Nick.
If you want true Cat A then you have to be able to do everything on one donkey.....how about two 1300 shp donks for an S76A......she'd be a little hard on fuel I think.
The problem in Canada is some of our helipads are restricted to helicopters that are not yet off the drawing board. Pilots are thinking that their Cat A birds are certified to land there.....IMHO they are not.
Until the operators buy the new generation aircraft just close these restricted helipads.....that's about what the restriction accomplishes.
If you want true Cat A then you have to be able to do everything on one donkey.....how about two 1300 shp donks for an S76A......she'd be a little hard on fuel I think.
The problem in Canada is some of our helipads are restricted to helicopters that are not yet off the drawing board. Pilots are thinking that their Cat A birds are certified to land there.....IMHO they are not.
Until the operators buy the new generation aircraft just close these restricted helipads.....that's about what the restriction accomplishes.
Last edited by Xnr; 3rd Jan 2003 at 01:55.