Dtango/HT/Pyro

[F4UDOA]

Heya's

Just did a little cut and paste with the F4U and F6F stall charts. Actually surprised me a little bit. When you use full flaps the F4U has a lower stall flap power on than the F6F. This is shown on the chart but stands out much more when the CAS charts are considered. The F6F-5 adjust about 6.5Knots at 80Knots with full flap while the F4U-1D adjust down about 3knots at 66Knots. This accounts for about 10Knots lower stall for the F4U-1 with full flaps.

[F4UDOA]

Punt,

I hate being ignored!!:mad:

[Shane]

Originally posted by F4UDOA
BTW. Neither stall is correct in AH. The F4U-1 stall 25% fuel(11,000LBS) in AH is 90MPH anyway you slice it. It won't takeoff until exactly 90MPH either which ties up my whole thread about not taking off a carrier deck. If the stall is to high it won't lift off in time.

i took off from a ground base full flaps, wep, 25% gas in f4u-1d

i lifted off at 71mph.  i might be able to eke a little better if...

i had rudder pedals (twisty stick), used manual trim (used CT and auto t/o up to a point).

i was a little slow in raising my gear.

enjoy the film.

i got the f6f off at 71 mph too.. might be able to do a wee bit better. 25% full flaps/wep.

note:  what effect do the hardpoints for ord have on these?  what exactly is included in those weights? ammo?

[Innominate]

Where is the f4u stall speed there?

[hitech]

Punt,

I hate being ignored.

Knock that crap off F4UDOA, we have had a very long discusion on this topic concering the F6F, juryies deliberating for a while.



HiTech

[F4UDOA]

Jeez,

1. One thing you guys don't understand is that your deliberating. I'm just sitting here watching the threads go by. Not trying to be a jerk, just trying to continue the dialog. If you said your deliberating I would just shutup but instead the thread just ends and goes away. Also I keep using the F4U because I have volumes of data for it that I don't for the F6F (or any other). It's the most well documented warbird in History.

2. If you have a sec to read this I think it's interesting even if it has nothing to do with AH.

3. My gas heat is out in my house today. Waiting for the repair truck but it's 25 degrees outside. Typing to keep my fingers warm.


Disclaimer!!

THIS POST HAS NOTHING TO DO WITH AH OR HTC.

4. I was just looking at this NACA doc that shows the F4U Clmax at 1.88 with full flap "prop installed" and I assume windmilling.

5. Checked Full flap stall speed in flight manual 11,300LBS power off Clmax =1.90.

6. Checked Vought doc I have on power off stall at 12,061LBS at 89MPH CLmax =1.90

7. Power on stall 76MPH Clmax full flap from the flight manual =2.4. So I just realized that the NACA doc Clmax  for Prop installed and power on Clmax are two different things. <==this was/is the point of my post.


I am officially relaxing/freezing!!  

[Wotan]

I just upped a f4u-d with 25% gas no wing from a ground base at 70-71mph. I have the film to.

no wep either

[hitech]

F4UDOA: Your touching limits here. Take this out of your piece of the post then you could claim your just talking F4U v F6F and nothing to do with ah.

BTW. Neither stall is correct in AH. The F4U-1 stall 25% fuel(11,000LBS) in AH is 90MPH anyway you slice it. It won't takeoff until exactly 90MPH either which ties up my whole thread about not taking off a carrier deck. If the stall is to high it won't lift off in time.

HiTech

[F4UDOA]

Done.

When I typed that I forgot my takeoff test were based on 2K bombs and rockets. With those test I remember 90MPH was the magic number to lift off.

With the test on stalls with 25% fuel I cannot hold the nose level below 85MPH but I can takeoff like Wotan and Shane said at 71MPH. Why the differance I don't know. What I am trying to figure out is what Clmax data is HTC using and compare that to the manuals.

In anycase the data from the manual is valid. The CAS charts are there too. I always ask that someone else(from the community)  to test and post results. JAB did many of the carrier test. Sometimes Auto trim can cause bad results.

In anycase if you say your looking at it that's good enough for me. Like I said a simple "We are looking into it" is enough. But when the thread just ends I keep going.

The Clmax stuff I just realized this morning. I thought the flaps were adding wing area. I didn't realize that there was a difference in Clmax from no prop to prop installed and windmilling, to power on. The 1.88 number is simply prop installed not power on which raises the number to 2.4.

[fats]

Not too big on the physics thing. Isn't there something called ground effect that helps to generate lift with in certain height from the ground ( span width or something )?

How wide would the "ground" have to be for ground effect to occur? Would CV deck be wide enough? Does AH calculate ground effect and does it do against the CV deck or just terrain polys?


// fats

[BigGun]

Kinda funny how you say "Done" then ramble on for 5 more paragraphs.

[Puke]

I actually find these types of posts interesting and probably educational.

[F4UDOA]

Good point Fats.

Never thought about ground effect.

Puke,

I think these post are very interesting. Not as many engineer types on the boards as there used to be. Such as Wells, Niklas and others. Although I do have a knack for getting under peoples skin. I do that in peson too. I have been described as brutal or abrasive on occasion.

BigGun,

The done was in reference to the paragraph that HT copied into his post. What I meant was that I edited it out of my original post.

I used the Columbo method of making my point. I say "just one more thing" then I ramble on for a half hour.

[hitech]

The post types are fine, just need to understand that collecting data is not all that simple. For instance take the stall to wieght table F4UDOA has posted. It dosn't lable it IAS or CAS, this can be a big difference, don't know which chart it is, in the same book he took that from it contradicts itself in stall speed.In that same manual I looked at the IAS to CAS table , and it simply dosn't seem to make any since.
Next you need to know was that a tested stall speed or just calculated from a Max CL, Simple thing like changeing CG with same weight will change the stall speed.
Next was it ment for rotate speeds or just a general gideline. In the end just grabing one point of data from 1 table dosn't always meen it's correct.

It has to fit in with other pieces of information.


HiTech

[F4UDOA]

HT,

I'm pretty sure I know why that data contradicts itself in the F6F manual.

The lower figures represent the F6F-3 which has a very large CAS correction of approx +12Knots at lower speeds. If you add the 12knots to the IAS the stall speeds are inline with those in the F6F stall chart which I believe is based on the F6F-5.

I believe any stall speed is a guide line and not an exact. But as it relates to AH I believe there is a parity that exist with most A/C. I think that these characteristics are distinguishing features of these birds and should be recognized.

From a non AH point of view I would like to see more feedback from an engineering perspective. The community is not the same as it was a couple of years ago for whatever reason. I never thought I would appreciate Niklas. It may not be the point of view I want but at least it's a point of view.