Welcome, Guest. Please Login or Register
YaBB - Yet another Bulletin Board
  Welcome to our forum.

FFDS Home | TIPS Section | Tutorials Section | Resources Section | Utilities Section

Military | FSDS | Jetliners | Real Planes Section | Gmax | Rotorcraft | Business | Civilian

  HomeHelpSearchLoginRegister  
 
 
Page Index Toggle Pages: 1
Send Topic Print
time to start the FDE - Lol, now what? (Read 3074 times)
23rd Jun, 2010 at 9:49pm

dmaher   Offline
Spline Extruder
I love YaBB 1G - SP1!

Posts: 229
***
 
I think this type of post is sometimes a little irritatingÖbut here goes anyway Wink

Where do I start?

Iíve convinced myself I can do the flight model, but now Iím sort of overwhelmed.
I have no experience....but I can do lot's of small jobs one after the other Wink

I believe I have the aircraft.cfg specís right.
And Iíve installed AFSD v3.75 and AAM V2.2.
Lol, now what?

What are, letís say, the 8 steps to making a flight model?
Can anyone comment?

Thanks,
Danny



Here's the subject - an RV7

Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register
 

Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register&&&&&&
IP Logged
 
Reply #1 - 23rd Jun, 2010 at 11:12pm

Au-MaV   Offline
Inspecteur des Polygonnes
Whatcha lookin at
Adelaide South Australia

Gender: male
Posts: 1956
*****
 
Hi
get as much data as you can find
is it freeware or payware? if its freeware then spending some $$ on airwrench may be a good investment.
If payware then you have to balance the time needed to get up to speed on the black art or pay a 3rd party to do the number crunching.
With airfiles its a matter of having to work out what is what from what you can find on the net and trial and error.
not much help  Smiley
Wozza
 
IP Logged
 
Reply #2 - 23rd Jun, 2010 at 11:17pm

Milton   Offline
Inspecteur des Polygonnes
Props forever!

Gender: male
Posts: 737
*****
 
Danny,

Great looking effort there  Smiley

If you still have FS2004, in the aircraft folder is a folder called Templates.  It contains 2 single engine prop flight models; one for a 170 HP fixed prop and one for a 270 HP CS prop.  That is one route to get started.

Of course you could also use any default aircraft that closely resembles your engine, HP, weight, speed characteristics.

Another option if this is freeware is to use Jerry Beckwith's Airwrench.  It is free for single engine, freeware work.
Alternately, if payware, Airwrench is very inexpensive and will deliver performance specs on the numbers.
You can get it here: Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register

Another option is Jerry's Flight Model Workbook.  Fill out the forms and watch it generate results.  You will need MS EXCEL for this one.  Freeware.

Another option if you have FS2004, is to use FSEdit.  The process is tricky but if used correctly will yield good results.  Unfortunately, dang few people ever spent the time to learn the processes and controlled the updates so it got a bad name.

Next option is to find someone who can do this for you who has good knowledge and tools.

Last option if you have a few months to invest is do it your self from scratch and learn all the ins and outs.  You can do this if you have knowledge of Aerodynamics principles and feel comfortable manipulating tables of data.

Hope this helps.
 

Milton Shupe&&Dash 7, Aero Commanders, Howard 500, D18S, Spartan 7W, A-26B/C,† XA38 Grizzly, DH-80A, AT-11, 427 Pinto Stock Car, The "Grumman Seven", Avia 51, 156, 56, 57
IP Logged
 
Reply #3 - 24th Jun, 2010 at 3:10pm

dmaher   Offline
Spline Extruder
I love YaBB 1G - SP1!

Posts: 229
***
 
Thanks, for the great advice Smiley
It is a payware project, so I appreciate this rules out some options.
On the upside I think I have lots of good reference material, and access to ďtestĒ pilots.

Iím currently using SingleEnginePropHP.air from FS9ís Mooney. (Ported to FSX)
Likely I should replace that with the .air from FSXís Mooney - now that I think of it.

I chose this airfile for its constant speed propÖmy RV is a 180hp with a C/S prop.
But the wings (Mooney vs RV) operate very differently.
The RV7 is a thick, low aspect ratio, Hershey bar wingÖI think itís got plenty more induced drag.
They have comparable top speed, but for the RV itís on account of its very light weight and high power.

Using the [flight_tuning] section of the aircraft.cfg I can get an approximate early result.
But Iím guessing these scalars donít constitute a proper foundation.
So Iím interested to dig a little deeper.

I think my strategy will be to get a handle on the wing design and see what it takes to define it in FS.

But first, Iíd like to have a look at Jerry's Flight Model Workbook.
It sounds like a good introduction.
I will send Jerry an email.

Danny
 

Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register&&&&&&
IP Logged
 
Reply #4 - 8th Jul, 2010 at 10:41am

atc4usaf   Offline
Point Pusher
I love YaBB 1G - SP1!

Posts: 42
*
 
Research, research, and more research. †I don't know what aircraft it is but look at the TCDS information from the FAA for the aircraft, engine, prop:

Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register

Secondly, research every entry and find the correct data. †Look at the engine manufacturer's website, and as I said above, the TCDS. †The prop TCDS will give you the prop weight... which is needed to find the prop MOI. †If you have trouble figuring out the prop pitch in degrees (sometimes the props are defined as inch-pitch props. †This means that the prop will travel x-amount of inches for one revolution. †The farther it will travel, the higher the angle), a guy I e-mailed at Sensenich Props told me that 2 inches of prop = .6 degrees. †So the 60" prop that I have on my Archer in real life has a pitch of 18 degrees.

If it's a Real World aircraft, find the highest resolution 3-view drawings you can and start measuring. †You have to calibrate the drawings to be able to convert. †I like to use millimeters since it is easier and can be more accurate. †So if you have a top-view, you measure the wingspan in mm. †Divide the actual wingspan by your measurement and you'll get a fraction. †You'll then multiply any lateral measurement in MM by that fraction. †Example: I'm working on a L10 Electra. †Wingspan of 55'. †on my drawing that I printed out, it is 257mm. †55'/257mm=.214. †So if I want to know what the span of an aileron is, I measure that: 49.5mm and multiply by my conversion factor of .214 to get 10.593' for one aileron span. †Smiley

But if it's a design that you made, you'll have this information in your design program: FSDS, Gmax, etc.

To get the data for the prop tables, I use a beautiful program called Javaprop. †It is a miracle worker with props. †Just remember to read the directions as you have to define the atmospheric conditions †you're operating in. †I use cruising altitude and that seems to work.

But there's so much involved. †The dynamic stability control derivatives in record 1101 in the .air are very difficult to actually calculate. †I use DATCOM published by the DAR corporation to try to figure them out. †I've been working on an excell pspreadsheet for a long time, but I'm still digging through it.

It's a lot of leg-work. †But I'll try to help if you'd like some walkthroughs.
 
IP Logged
 
Reply #5 - 11th Jul, 2010 at 11:45pm

dmaher   Offline
Spline Extruder
I love YaBB 1G - SP1!

Posts: 229
***
 
Thanks! This is all great advice.
Iím making slow progress to start, but Iím beginning to build some momentum.
Iíve spent most of my time so far working in the aircraft.cfg
Just for fun Iíll post a few drawings that establish some of the critical dimensions.
Actually I made these drawings to outsource the flight model, but now Iím happy to use them myself too:)

Danny


Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register

Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register

Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register
 

Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register&&&&&&
IP Logged
 
Reply #6 - 12th Jul, 2010 at 4:39pm

hews500d   Offline
Spline Extruder
I love YaBB 1G - SP1!

Posts: 119
***
 
Danny, that is going to be one sweet model once released!  I've been keeping my eye on it since learning about it being under development.  If you need any beta testers please keep me in mind  Wink

Darrell
 
IP Logged
 
Reply #7 - 14th Jul, 2010 at 12:22am

dmaher   Offline
Spline Extruder
I love YaBB 1G - SP1!

Posts: 229
***
 
Thanks, DarrellÖI havenít started proper testing but Iíll keep your offer in mind.

This is sort of overkill (actually itís a product of major procrastination )
..But I donít use Excel, so sometimes I use FSX to do math for me.

Hereís a gauge thatíll calculate propeller_moi; if you input weight, diameter, and # of blades.
Iím not 100% sure itís right Wink But the numbers seem reasonable.
In metric I can use Kg for mass but in imperial I have the change lbs to slugsÖis that right?


Code:
<!--
	PROPELLER MOMENT OF INERTIA

	Determines propeller_moi
	This gauge calculates an average between the rod and disc methods of finding moi.
	As opposed to using point mass method

	moi rod:	Jr=2/3m r^2
	moi disc:	Jd=1/2m r^2
	moi:		J=(Jr+Jd)/2

	Formula From:
		http://www.mh-aerotools.de/airfoils/prop_precession_english.htm#Determination_of_the_Moment_of_Inertia

	Specific Prop Reference:
		Prop Manufacturer: Hartzell
		Prop Model: HC-C2YK-1BF/F7666A-4
		TCDS#:P-920
		weight: 51.0+1.2 lb.
		diameter: 72"
		blades: 2
-->

<Gauge Name="deBug">
<Size X="128" Y="256"/>

<!-- ### inputs ### -->
<Macro Name="propMass_lb">52.2</Macro>		<!-- Input, total prop weight in pounds -->
<Macro Name="propDiameter_ft">6</Macro>		<!-- Input, prop diameter in feet -->
<Macro Name="numBlades">2</Macro>		<!-- Input, number of prop blades -->

<!-- localVars -->
<Macro Name="mass">L:mass,number</Macro>
<Macro Name="radius">L:radius,number</Macro>
<Macro Name="moiRod">L:moiRod,number</Macro>
<Macro Name="moiDisc">L:moiDisc,number</Macro>
<Macro Name="moi">L:moi,number</Macro>


<!-- Calculation -->
<Update>
	(L:moiCalc,bool) 0 ==
		if{
			@propMass_lb 32.17405 / @numBlades / (&gt;@mass)
			@propDiameter_ft 2 / (&gt;@radius)
			@numBlades (@mass) 2 * 3 / (@radius) sqr * * (&gt;@moiRod)
			@numBlades (@mass) 2 / (@radius) sqr * * (&gt;@moiDisc)
			(@moiRod) (@moiDisc) + 2 / (&gt;@moi)
			1 (&gt;L:moiCalc,bool)
		}
</Update>


<!-- Display -->
<Element>
	<Element>
		<Position X="15" Y="5"/>
		<FormattedText X="100" Y="12" Length="30" FontSize="11" Color="gray" BackgroundColor="black" Bright="Yes">
		<String>propeller_moi</String>
		</FormattedText>
	</Element>
	<Element>
		<Position X="15" Y="20"/>
		<FormattedText X="100" Y="10" Length="30" Color="gray" BackgroundColor="black" Bright="Yes">
		<String>total prop weight: %(@propMass_lb)%!4.3f! lb</String>
		</FormattedText>
	</Element>
	<Element>
		<Position X="15" Y="30"/>
		<FormattedText X="100" Y="10" Length="30" Color="gray" BackgroundColor="black" Bright="Yes">
		<String>prop diameter %(@propDiameter_ft)%!4.3f! ft</String>
		</FormattedText>
	</Element>
	<Element>
		<Position X="15" Y="40"/>
		<FormattedText X="100" Y="10" Length="30" Color="gray" BackgroundColor="black" Bright="Yes">
		<String>mass: %((@mass))%!4.3f! slugs</String>
		</FormattedText>
	</Element>
	<Element>
		<Position X="15" Y="50"/>
		<FormattedText X="100" Y="10" Length="30" Color="gray" BackgroundColor="black" Bright="Yes">
		<String>radius: %((@radius))%!4.3f! ft</String>
		</FormattedText>
	</Element>
	<Element>
		<Position X="15" Y="60"/>
		<FormattedText X="100" Y="10" Length="30" Color="gray" BackgroundColor="black" Bright="Yes">
		<String>moi rod method: %((@moiRod))%!4.3f! slug ft2</String>
		</FormattedText>
	</Element>
	<Element>
		<Position X="15" Y="70"/>
		<FormattedText X="100" Y="10" Length="30" Color="gray" BackgroundColor="black" Bright="Yes">
		<String>moi disc method: %((@moiDisc))%!4.3f! slug ft2</String>
		</FormattedText>
	</Element>
	<Element>
		<Position X="15" Y="80"/>
		<FormattedText X="100" Y="10" Length="30" Color="gray" BackgroundColor="black" Bright="Yes">
		<String>moi median: %((@moi))%!4.3f! slug ft2</String>
		</FormattedText>
	</Element>
</Element>
</Gauge> 

 

Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register&&&&&&
IP Logged
 
Reply #8 - 14th Jul, 2010 at 9:11am

hews500d   Offline
Spline Extruder
I love YaBB 1G - SP1!

Posts: 119
***
 
Thanks Danny!

Good idea on the gauge.  I checked Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register

and it does look like slugs/ft.sq. are the imperial units.

Darrell
 
IP Logged
 
Page Index Toggle Pages: 1
Send Topic Print