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JtD
02-16-2010, 11:42 AM
I prepared an Excel sheet that allows you to calculate turn performance of a plane based on the basic aerodynamic laws. You'll just have to enter the proper plane data. I made this so that the forums charlatan can no longer mislead you. I hope it will be useful to you, if you have any questions, please don't hesitate to ask.

Link to download. (http://mitglied.lycos.de/jaytdee/estimate_turn.xls)

It's been made with a German copy of OpenOffice, couldn't test compatibility with International MS Office. Hopefully it works.

Before you ask, the charts are on the fourth to seventh table.

Note: Some internet safety maniacs have decided that the site I host my stuff on is an "attacking website". Whatever that means. This does not refer to my parts there. So you can, certainly with smaller risks than using Google, ignore that warning and download the file from there.

thefruitbat
02-16-2010, 04:19 PM
Thanks JTD, thats really cool, shall have a play. Works fine on my 'english' copy of excel.

cheers fruitbat http://forums.ubi.com/images/smilies/25.gif

mhuxt
02-16-2010, 04:32 PM
I guess the axis titles on the graphs don't change with the units used?

M_Gunz
02-16-2010, 05:02 PM
Works on my web copy of OpenOffice.

Top Speed -- is that for the altitude chosen for the turn?

Kettenhunde
02-16-2010, 06:57 PM
First glance it looks pretty good JtD. Who gave it to you?

Now input data for the P47D22 and Spitfire Mk IX and set the altitude for 28,000 feet. If you sheet is correct, you should see the P47 can sustain a larger load factor than the Spitfire Mk IX Merlin 66.

P47D22:

weight 13583lbs
Power 2300hp
Propeller efficiency 0.85
Wing area 300
wing efficiency 0.85
Aspect Ratio 5.61
Raise the stall speed to ~100Kts to realign the CLmax for weight.

If the chart is right, your Vmax will be ~234KEAS or 424mph TAS.

For the Spitfire Mk IX Merlin 66

weight 7450lbs
Power 1050hp
Propeller efficiency 0.85
Wing area 242
wing efficiency 0.85

If the chart is right, you speed will be ~215KEAS or ~390mph TAS.

Kettenhunde
02-16-2010, 07:46 PM
I just checked your sheet....

You know the Cdo for the P47 goes up with altitude.

It should have a direct relationship so that Cdo2 = Cdo1(sigma2/sigma1).

As density goes down, parasitic drag should go down. The P47 is pretty velocity stable as its FTH is 30,000 feet.

That is not correct behavior.

For example, velocity going from 20,000 to 30,000 feet we should see ~1.07 or 7% increase in parasitic drag due to velocity.

http://img29.imageshack.us/img29/4563/parasiticdrag.jpg (http://img29.imageshack.us/i/parasiticdrag.jpg/)

We should see about a ~30% reduction in parasitic drag due to density over that same 10,000 foot increase in altitude.

Your sheet does not reflect those relationships.

In fact, it is the opposite.

AndyJWest
02-16-2010, 07:50 PM
Can we have a tool for estimating how long this debate is going to last? If you gents don't come to a consensus soon, I think it might be quicker to build a plane from scratch and try it. http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

Kettenhunde
02-16-2010, 08:05 PM
No doubt. Problem is that when you know computers but do not know the aerodynamics, you think it is easy to parrot a few formulas in a spreadsheet.

You do things like mistake density for density ratio, don't understand EAS or its relationship, have no idea what the normal relationships for our forces, mix up formulation and procedures, make assumptions that do not work, and have long discussion on nonsense like "energy retention".

JtD
02-16-2010, 10:24 PM
Originally posted by thefruitbat:
Thanks JTD, thats really cool, shall have a play. Works fine on my 'english' copy of excel.

That's good to know, and you're welcome.



Originally posted by mhuxt:
I guess the axis titles on the graphs don't change with the units used?

No, the units on the graphs stay as they are. I could add another page or two with graphs for different units.



Originally posted by M_Gunz:

Top Speed -- is that for the altitude chosen for the turn?

Yes, that's right. There's a note in the "top speed" box which also says that. There are a couple of hints given that way, so look out for the notes.

M_Gunz
02-16-2010, 11:49 PM
Notes? I haven't dug into the cells and I see two lines of comment at the top of plane_data.

And after looking I found em! Never used that before but then I was trained on Lotus and used
a Lotus-clone (AsEasy) up till about 10 years ago. I still say that 1-2-3 was a better product.

JtD
02-17-2010, 12:36 AM
I'll add a line saying you gotta look for the notes. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif I use them plenty, it's the best way to comment on things where you feel you need to comment, but don't think it should be on the interface.

M_Gunz
02-17-2010, 06:20 AM
Oh it's very cool be sure!

Kettenhunde
02-17-2010, 07:16 AM
(K45*9.81*plane_data!$C$8)^2/(plane_data!$B$35*0.5*A45^2*1.225*PI()*plane_data! $C$26^2)

I think I might have found your problem. You need to vary the density with altitude if you work in TAS.

Holtzauge
02-17-2010, 12:51 PM
Excellent stuff JtD. Really nice with the plots. Turn rate, turn times, radius etc.

Could not help noticing the P-47 example did not quite make it up to 2.57 in sustained loadfactor did it....

In fact the max sustanied loadfactor I can read out from your chart does not look to different from the one I posted n=2.11 max as a response to Kettenhundes initial claim of n=3.75.

But I guess the reason they are so similar is because neither of us (You, me, Wurkeri or FC) seem do the same "corrections" as Kettenhunde.....

JtD
02-17-2010, 01:13 PM
My input data is different from what you used, I think my wing efficiency is lower, the engine more powerful, smaller cdo (not a direct input) among other things.

I ended up with 2.18 which still is pretty similar and backs up your analysis. Not that it needed any backup, but it never hurts to validate calculations.

2.57 at 3280 hp and 3.75 at 7280 hp, if you're interested.

Thanks for the compliments. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

T_O_A_D
02-17-2010, 01:20 PM
When I went to get it, I got this warning.

Has anyone got it and made sure the site hasn't added something JTD didn't intend.

http://img.photobucket.com/albums/v37/T_O_A_D/Computer/attacksite.jpg

JtD
02-17-2010, 01:37 PM
I downloaded it from there myself and it is the same file I uploaded.

lycos.de is a free webhosting service that supports thousands of websites and I can imagine that there are a few black sheep. It has nothing to do with my part there.

So for all I know, it is safe.

Jumoschwanz
02-18-2010, 08:47 AM
Originally posted by Kettenhunde:
No doubt. Problem is that when you know computers but do not know the aerodynamics, you think it is easy to parrot a few formulas in a spreadsheet.

The other problem is that "gamers" will take a look at tools like this and then complain that they were not able to out-turn so-and-so online the other night and that things should be fixed in the next patch of the sim!

A lot of pilots with more experience than their foe in a a6m5 Zero will out-turn them and shoot them down even if they are flying a C-47 cargo plane...

Oleg and crew, and the developers of the official patches for this sim are as smart or smarter than 99.9% of those posting "miracle tools" on any forum, so they are not really worth the time as anything but amusing toys....

M_Gunz
02-18-2010, 10:12 AM
When it's so much easier with IL2Compare?

JtD has done a segment of the community a nice favor in making this.

Kettenhunde
02-18-2010, 04:06 PM
Oleg and crew, and the developers of the official patches for this sim are as smart or smarter than 99.9%


AFAIK, Oleg Maddox and Bill Stealey of iEN's Warbirds are the only Aeronautical Engineers in the WWII aerial combat game business.

JtD
02-23-2010, 11:58 PM
The tool has been updated, it now contains a couple of more graph sheets, the results are now presented in km/h TAS, mph TAS, km/h EAS and mph EAS. I also added a couple of examples. It's also been validated in the process. Download still the first post.

Folks who downloaded within 15 minutes after this posting might have to dl again, wrong labels on the charts. Sorry.

TheGrunch
02-24-2010, 12:28 AM
Thanks JtD! It's really cool to see people putting the time and effort into stuff like this. http://forums.ubi.com/images/smilies/25.gif

M_Gunz
02-24-2010, 03:32 AM
Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Oleg and crew, and the developers of the official patches for this sim are as smart or smarter than 99.9%


AFAIK, Oleg Maddox and Bill Stealey of iEN's Warbirds are the only Aeronautical Engineers in the WWII aerial combat game business. </div></BLOCKQUOTE>

Oleg has some others with him according to posts going back years ago. One or two, I am not sure and also about full
or part time. Perhaps the Rise of Flight group has as well.

With the winding down of resources from the burning-spree of the last 100 years there may be more such people
looking for other things to do than expected. More qualified people than jobs is not a new story.

I've seen on web from Oleg's background he was also a Sukhoi test pilot and did some work in South America.
He has been fortunate to get around the world and do interesting things. I wonder what his son may do?

Kettenhunde
02-24-2010, 04:08 AM
It's also been validated in the process. Download still the first post.

Really??

Better check that one again.

JtD
02-24-2010, 08:45 AM
Originally posted by TheGrunch:
Thanks JtD! It's really cool to see people putting the time and effort into stuff like this. http://forums.ubi.com/images/smilies/25.gif

You're welcome! http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

JtD
03-15-2010, 01:57 PM
I gave the tool a major update. I figured since it was intended for relative performance, it should have a side by side comparison feature for two planes, much like il2-compare. This is in now.
You can compare two different planes, or you can take one plane and see what changes if you change a certain parameter, it's certainly interesting and will help to illustrate basic flight physics.

I also gave the data table some sort of formatting, so that curious folks will have it easier to find what they are looking for.

Link is still in the first post. Have fun.

Kettenhunde
03-15-2010, 03:03 PM
Never mind, I rechecked and you still using the wrong units.

JtD
03-15-2010, 11:24 PM
Sorry again, seems to become a bad habit, I missed a wrong reference in the p2 table, regarding climb and level acceleration. Nothing that goes into the charts, so I didn't spot it right away. The fix has been uploaded.

JtD
03-15-2010, 11:36 PM
Originally posted by Kettenhunde:
Never mind, I rechecked and you still using the wrong units.

When you were asked to prove this claim, you only posted excuses. Many times, over several days. By that you've shown that you're not qualified to assess the workings of the tool.
Added to that, I proved your claim wrong. Stop trolling. http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

irR4tiOn4L
03-15-2010, 11:42 PM
I wouldnt say that claim was proved wrong. Some accepted there was an error in the table.

I wouldnt say that detracted from its overall usefulness and as you say, no viable alternative has yet been presented. Still, with M_Gunz working on a fix the best course might be cooperation, or waiting to see the outcome of that effort.

JtD
03-16-2010, 12:03 AM
Originally posted by irR4tiOn4L:
I wouldnt say that claim was proved wrong. Some accepted there was an error in the table.

What "some" think or not has very little to do with the proof. "Some" prefer to go with unfounded claims instead of proper math. There are folks around here who'd jump out of the window if you insisted they can fly if they just flap their arms hard enough. In particular if you have a short nose. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Kettenhunde
03-16-2010, 05:11 AM
"Some" prefer to go with unfounded claims instead of proper math.

Unfounded? The mathmatical proof's were given to you as well as the rules straight out of college text.

I think people can read. I told you the fix and even cut and paste the line of code for you.

That does not change your Cdo issue either.

JtD
03-16-2010, 09:48 AM
Originally posted by Kettenhunde:

Unfounded? The mathmatical proof's were given to you as well as the rules straight out of college text.

Blablabla and a lie.


I think people can read. I told you the fix and even cut and paste the line of code for you.

No, you posted a claim, which you failed to prove when asked. Which is not surprising, considering it's wrong.


That does not change your Cdo issue either.

I can enter the proper values so it works properly. It's not my fault that you can't.

Can't you go and open up another topic and troll there?

Kettenhunde
03-16-2010, 10:39 AM
Kettenhunde says:

In this case, your math is correct but the principles are wrong. Do you know understand that formulation has rules of use? In this case, density is factored into the equation for True Airspeed. In order to keep our equal sign correct, we need to reflect that in our power.


http://forums.ubi.com/eve/foru...911010438#6911010438 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2891026238?r=6911010438#6911010438)


Here is what is confusing people.

Lets break down what is happening on the Thrust required <drag> side of the equation.

in TAS:

Dynamic pressure = sigma *(KTAS)^2 / 295

Dynamic pressure = sigma *(KEAS/SQRT sigma)^2 / 295

Dynamic pressure = sigma *(KEAS/SQRT sigma)*(KEAS/SQRT sigma) / 295

Dynamic pressure = [sigma*(KEAS*KEAS/SQRT sigma*SQRT sigma)]/ 295

Dynamic pressure = [sigma*(KEAS*KEAS/SQRT sigma^2)]/ 295

Of course, the square root of sigma squared is sigma.

Dynamic pressure = [sigma*(KEAS*KEAS/sigma]/ 295

Sigma cancels and we are left with:

Dynamic pressure = (KEAS*KEAS]/ 295 or the expression for EAS dynamic pressure.

Just because it cancels does not mean the correct thing to do is add it in to the other side of the equal sign on the Power Available side when we are using EAS.

You still have to follow the basic rules of math.

If you work in EAS, sigma is not factored into the equation and the results are converted at the end.

If you work in TAS, you must add in sigma on both sides of the equation. Your parasitic drag will vary IAW density effects and subsequently vary the value of e.

The end result, done correctly will be very close in either method.


http://forums.ubi.com/eve/foru...901091438#4901091438 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2891026238?r=4901091438#4901091438)

And more...it goes on and on.

http://forums.ubi.com/eve/foru...021060438#7021060438 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2891026238?r=7021060438#7021060438)

http://forums.ubi.com/eve/foru...801010438#9801010438 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2891026238?r=9801010438#9801010438)


http://forums.ubi.com/eve/foru...521088238#9521088238 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2891026238?r=9521088238#9521088238)

http://forums.ubi.com/eve/foru...211083338#6211083338 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2891026238?r=6211083338#6211083338)

http://forums.ubi.com/eve/foru...931096338#4931096338 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2891026238?r=4931096338#4931096338)

http://forums.ubi.com/eve/foru...811049338#7811049338 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/2891026238?r=7811049338#7811049338)

Sad thing is if you were not so pig headed, you could have great product there.

If you work in TAS without measured values and detailed analysis, you will get a larger margin of error due to the thrust characteristics of propeller aircraft because your margin of error is pushed to the velocity our performance occurs.

Those are the facts.

JtD
03-16-2010, 11:21 AM
Fairy tales again.

Now can't you go and troll elsewhere?

JtD
03-19-2010, 11:12 AM
I uploaded another improved version, this time it is just the presentation of the charts. You now have a limited auto-size feature and solid lines instead of dots. Excel will only auto-size from zero to max, but OpenOffice will auto-size from min to max. But even the Excel function will give you a lot more info now, in particular for high altitude, where the previous version would just show a dozen dots or so.

The link is still in the first post.

M_Gunz
03-19-2010, 05:30 PM
Originally posted by irR4tiOn4L:
Still, with M_Gunz working on a fix the best course might be cooperation, or waiting to see the outcome of that effort.

What I do is no 'fix' and what JtD does is to me no problem needing to be fixed.
We likely get the same results since to be honest he is one of the people helping ME understand what I'm doing.
Hell of a note to start some stupid song and dance about me fixing his work. Political commercial material there....

How about you fix your view since that does need a whole LOT of fixing?