Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: F4UDOA on October 10, 2002, 08:04:11 PM
-
Ok Gents,
Riddle me this.
At a gross weight of 12175LBS the F4U-1D should lift off at 52" of MAP(Mil power) in a 29MPH headwind(25Knots) in 282FT with full flap.
The length of the flight deck from the spawn point is 556FT. So the F4U-1D should lift off the deck in roughly half of the deck space available for liftoff without rollback.
I have tried it many times and it seems impossible to me.
Any takers?? Film it post it.
I don't think it can be done.
Why?
Because in order to acheive this the F4U-1D must be able to achieve a speed above the stall for the F4U's gross weight. That speed is 87.5MPH full flap no power. Roughly 82MPH full flap power on. And it must be able to reach this speed in half of the availble deck space and in AH it cannot.
To me it says two things.
A. The low end accelleration is not sufficient to reach the correct speed in the distance specified in the manual and historic specs. which is 82MPH in 282FT with full flaps deployed. It currently cannot reach that speed in that distance no flaps deployed.
B. Not enough lift from flaps. The stall speed no flaps is roughly correct in AH for the F4U-1D. But with flaps the stall goes down as low as almost 80MPH with power. At that speed in AH(on the digital viewer) you cannot fly even close to 80MPH. In fact you can't get below 90MPH. This shows me that flaps do not create enough lift.
1. Not enough acceleration.
2. Flaps not enough lift.
Here are the stats.
(http://mywebpages.comcast.net/markw4/19128170.jpg)
-
no wep
2 notches of flaps
one notch before rolling and second notch by island
-
You bastard!!
Actually I haven't had time to look at it.
Standbye.....
-
Errr,
Dude, that is a film of you taking off with bombs at rockets.
I want film of a takeoff full fuel and bullets NO bombs NO rockets.
Lift off in half of the deck (280FT). This should be with full flaps but if you can do it otherwise I would luv to see it.
Your speed at liftoff should be about 83MPH on the film viewer.
Try again??
-
my reading comprehension is bad at night...
best i can do is taking off right before the elevator..
-
Actually, far from trying to dispute you, I also wish the F4U in AH was somewhat better. I think it's rather under-represented in AH.
How did the late-model -1A's compare to the -1D?
J_A_B
-
Unfortunately right now I can't do any really good takeoff trials as my rudder control has problems. Just playing around I can get the thing airborne before the elevator, but with no real rudder control it's very sloppy. I'll see what I can do once I have rudder control again.
How large is the elevator and how far is it from the end of the flightdeck? And do we have a long hull or short hull Essex-class ship (this affects flightdeck length before the elevator)?
There are two possible ways to take off in short distances...you can either hold the elevator back until the plane flies off (careful not to stall it), or actually push forward as the plane gains speed to get the tail up, THEN pull back to fly it off. Which method is recommended in your F4U takeoff protocols? I prefer to simply hold the elevator back and keep the tail on the ground until the plane flies itself off.
It lifts off at around 83-85 MPH (hard to tell exactly) somewhat before the foreward elevator, as noted. I am cofident I could do slightly better if I actually had direct rudder control, as the constant yawing from using keyboard rudder doubtlessly bleeds some speed. I'm not posting this film because it's very sloppy and not really representative of a proper takeoff.
J_A_B
-
JAB,
The reason I am harping on this so hard goes back to the AH Beta. I have been argueing with HT specifically about the F4U climb and acceleration. I have always felt it was off and for various reasons I have always been argued off of my point by various engineer types.
Well this one is pretty cut an dry.
It is a straight line acceleration test meased at the correct weight, Altitude and power setting. By the book in full flap condition the F4U should be able to reach speed X in 286FT. and lift off. It covers both parts of my arguement.
1. Since the F4U cannot reach its minimum flying speed (approx 82MPH) in the 286FT specified in the manual it then can't liftoff.
Not enough acceleration.
2. Since even at 82MPH the F4U cannot liftoff it shows that the flaps do not provide enough lift.
Both of these issues go back to late 1999. Frankly I it is more of a crusade to prove I'm right as much as to get the FM fixed.
-
Please post me a pic showing the location of the 280 foot mark in front of the spawn point.
J_A_B
-
Very curious about this and I would love to see an official answer if possible. I believe the same thing about it that F4UDOA does also.
-
Reschke,
The final outcome of the testing was this.
You have to manually trin the aircraft almost as in the flight manual.
Right aileron down slightly. Right rudder about the same amount as the aileron. Slight nose up trim.
If you do this you can albeit difficult take off mil power from the carrier deck with 100% bombs and rockets.
I am sure that our F4U is slightly underpowered as I have never seen film of any carrier plane fall off the end of the deck like our F4U. Even Dolittles B-25's were actually climbing not falling at the end of the carrier deck.
Something in the low end accleration of the F4U is off. Unfortunately despite many attempts I have never been able to prove my point conclusively because I do not have the math or engineering backround to do so.
HTC has never responded officially.
-
Well after trying about 15 straight launches last night in an F4U-1D with anything from 100% fuel and full ammo (no rockets and bombs) to 25% fuel and full bomb load, rockets and ammo. I could not get any flight to continue past about 300 feet off the carrier. I tried trimming the aircraft in all manner of situations with no success.
Now on the other hand the F4U-1 is literally jumping off the deck for me with any loadout and the F4U-4 is similar. To me the 1C and 1D are automatic tower poppers for me. :D I will start working on setting the trim as you mentioned and hoping for the best.
-
One other tip for getting off the deck.
The F4U wants to stall and roll left, so manual trim is set right.
When you hit the end of the runway bank slightly right. It helps offset the stall.
-
After using the trim as you stated a couple of posts ago I was able to bring the F4U-1D off the deck 3 out of 5 times with 100% fuel and full ammo and heavy ord load.
Thanks guys for working on this.
-
I agree with F4UDOA completely. His numbers seem to back up his assertions. Why is HTC so quiet on this? Throw us a bone!
-
HiTech, please fix the F4U. The Corsair was a huge engine bolted to a sleek airframe. Yet the plane we have accelerates about as good as a steam engine going up Mount Everest.
-
the most success ive ever had with a D-hog off of CV (would NEVER try a loaded C-hog off CV) was to hit WEP...HOLD brakes until rpm's came up....at about halfway point hit full flaps (last notch gets engaged as you FALL off deck)...have finger on gear button..then wrestle it into air. I never try pulling back on stick until it runs out of deck--the rolling thing they mentioned earlier. Must admit..doesnt seem like the plane would have been approved for CV service if it started off so poorly
-
dang I forgot--there was discussion on chan 1 a few weeks ago about how to make F4 BACK UP on cv--tapping throttle just the right way---if ya notice..there is quite a bit of useable deck behind where game launches plane.
-
a picture's worth 1,000 words.
-
Shane: That is a hell of a radical takeoff you pulled there. You did get it up but it looked like it was going in for a second there right after takeoff.
Another thought:
I was watching a show (Thursday , December 26 06:00 PM - 07:00 PM Corsair: Pacific Warrior) where they were going over the F4U and its initial introduction to CV service. One of several pieces of footage they showed was of the VF-17 carrier trials where the Corsair bounced like a over-inflated basketball. On they other hand they showed the same aircraft practically jumping off the deck well before the end of the runway on the Essex class CV's and no wallowing like a pig in a mud pit either. :D
Anyway I found it very interesting; they had some pretty good interviews with the guys who flew it in both USMC and USN service.
-
Bump
-
Originally posted by Reschke
Shane: That is a hell of a radical takeoff you pulled there. You did get it up but it looked like it was going in for a second there right after takeoff.
well, i met the parameters desired, it wasn't pretty. :D i think i could have done a little better if i had started a bit of up elevator trim as soon as i got that 1 foot off the ground.
i didn't go in, tho... was in full control once it actually went to the right over the deck. i dunno if i lost any alt when i did that. nope, didn't lose any alt... i touched down breifly once again to 52 feet (which is where i think a little elev up trim might have helped.)
if you noticed i got that 1 foot of alt at 75mph, wep and full flaps without any extra trim involved. at this occurred approximately at the end of the towers before the fore 5" guns.
soooo.... hehehe, i guess it *is* possible and pretty much spot on. hell maybe the flaps work a little too well if i got that inital foot of alt at 75mph instead of 82mph.