CAPTAIN SIM FORUM - Print Page

Hi,

I can't find a table for the Vref of the 707...

I have found cruise performance, descent, climb, takeoff, all, but not Vref table.

Can hep me?

tanks.

Hi Alberto.

If you have downloaded the 707perf.zip from Avsim, in the 707performance2.pdf, there is a comprehensive table for the Vref of the 707.

If you haven't got it yet. Go and get it because it has great information in it. Search Avsim for 707perf.zip

Mark

Markoz wrote on Oct 5^th, 2010 at 3:44pm:

I have it, but i don't have see it.

You are the best mark. tanks!! :D

I don't see the Vref landing tables in that 707performance2.pdf either?

It has 13 pages right? Which one our you guys using?

Oops. Confusion. Page 6 has Takeoff speeds, I use the placard under the glareshield for landing!

This:

You can just see the bottom of it under the glareshield here:

Sorry guys. I copied them and put them in a references text that displays in the kneeboard.

Mark

There's a chapter "critical speeds" in the given documents from the Avsim file where you can read a wide range of data exceeding the shown placard (which still is a good source).
I don't know exactly the values for a correct calculation of the approach speeds then but I usually go with the always right 1.3 multiplier.

So if e. g. the aircraft has a given stall speed of 100 knots (which is an example of course) at the given weight and flap setting, multiply this critical speed with 1.3 and you have the save margin of +30.
You therefor aim towards 130 knots.
Winds might alter this value additionally.

As Airliners usually don't land like small General Aviation planes (big flare, near stall speed touchdown) but are flown onto the runway, this will give you a nice approach with a slow retarding throttle just before touchdown and very small pitch changes.
No need to get close to stall here.

I think we agree that those speeds and additional data would be best to come with the installer of the precious 707.
As seen on some other devs planes, a kneebord showing an overview of the most commonly used values would be fine too.
Maybe someone puts that into the wishes section of these forums.

I'm not good at handling html files but there might be a user around who collects some data and puts it into a kneebord file for everyone to load.
Friendly captains surely would appreciate this �:)

The 1.3 rule is safe. I view the speeds on the placard are a starting reference only, I haven't followed them exactly on the numbers but I feel they are close enough.

At 170,000-175,000 lbs, I approach at around 140 knots and she comes in really nicely. I spend most of the final approach tweaking the throttle to maintain the speed. I'm keeping an eye on everything that I possibly can as well. ;)

Mark

FYI

From the Boeing manual - this is for the 707, 727, 747, 767 & 757.

For every knot of extra airspeed add 50' to the landing distance. Ten knots fast would take 500' feet more runway.

Also, you would add 1/2 the gust to the VREF Ex. - 250/15 G25 you would add 5 knots as a pad to the approach airspeed.

Lou

Agreed, landings on short runways shouldn't be too far away from VREF, but approaching with 1.3 and retarding the throttles e. g. over the threashold will give you closer landing speeds without the need for going GA-like, meaning near stall and high flare pitch angles.

I saw some pilots talking about Airliners to come down very close to stall but you may agree that this should be the uncommon way of landing the big birds.

Gusts and too soon flares are great dangers there, at least expensive ones when e. g. the tail touches before the wheels because the pilot tried to do it extra smooth. ;D

Yes if you flew at the Vref speed for the weight you had the right speed.

There was sufficient speed for normal landing at that weight and flap configuration.
Where pilots got in trouble was holding the plane off to get a smooth landing.
That's where the tail strike would happen or worse - go off the far end of the runway in ground effect. :'(

Lou

Here's one of those "smooth" ones ;D

Feel free to click for a big picture
http://img801.imageshack.us/img801/2999/240801091106453.th.jpg

I wonder if this could be takeoff too ...
However, talking to the Airline Manager after such things must a least be as loud as opening the windows in flight.

Hi,

@Lou: I thought you added half the steady and all of the gust?

e.g. 250@15G30, add 7.5+15 = +23 kts to Vth? IIRC max. correction is 20 kts, so it would be Vth + 20.

I'm trying to find some data I used to have on 707 perf.

Best regards,
Robin.

Robin, you are correct! �:-[

It's been a while, but you would add the wind speed + 1/2 the gust to a max of 20kts.

Here is a quote from an AA pilot:
"AA uses the following formula:
"Approach speed = Vref + 1/2 Reported Wind + Gust.
Minimum approach speed = Vref +5.
Maximum approach speed = Vref +20."
(tailwind is always ignored)."

In the modern planes the Vref is figured by the computer.

CAPTAIN SIM FORUM
707 Captain >> 707 Captain >> Vref https://www.captainsim.org/forum/csf.pl?num=1286290725 Message started by Alberto on Oct 5^th, 2010 at 2:58pm