Aces High Bulletin Board

General Forums => Wishlist => Topic started by: Midway on April 15, 2014, 07:10:45 PM

Title: Dynamic Soaring
Post by: Midway on April 15, 2014, 07:10:45 PM
I wish that we can practice dynamic soaring with engines off (perhaps in the storch or mighty Spitfire). :airplane:

We would need horizontal layers of wind down low and close to no wind near the surface of large ocean waves (with the new water modelling).  The wind can be in any direction since the Albatross can use dynamic soaring to fly in any direction regardless of wind direction.  :)

When we run out of fuel after a fight we might be able to make it home if we learn the technique and if HTC enables it. :old:

Here is a video example: http://www.youtube.com/watch?v=F4zEaYl01Uw :aok

That is my wish. :salute
Title: Re: Dynamic Soaring
Post by: FLS on April 15, 2014, 07:25:03 PM
Have you tried it? You can set wind offline.

I expect the wind speed needs to be proportional to the glide ratio.
Title: Re: Dynamic Soaring
Post by: Midway on April 15, 2014, 07:27:06 PM
Have you tried it? You can set wind offline.

I expect the wind speed needs to be proportional to the glide ratio.

I don't know how to set it up.  If someone could create a custom arena (mission), I would download it and try it.

I think just a normal ocean wind pattern is ok.  Maybe 20 to 30 knots just above the surface (with near zero at the surface), but I'm no flight engineer.  Someone smarter than me would have to think about it.
Title: Re: Dynamic Soaring
Post by: grizz441 on April 15, 2014, 07:29:23 PM
Like an abatross!?
Title: Re: Dynamic Soaring
Post by: Midway on April 15, 2014, 07:29:48 PM
Like an abatross!?

Indeed!!!! :x
Title: Re: Dynamic Soaring
Post by: FLS on April 15, 2014, 07:36:00 PM
Go to options/arena setup/environment/wind.

Set a layer that starts higher than the airfield you're using. Note the altitude. That's your gradient
that you're going to be climbing above and diving under.

Since we don't have glide ratios like seabirds or sailplanes we might not gain much energy from 20 - 30 knot winds.
Title: Re: Dynamic Soaring
Post by: Midway on April 15, 2014, 07:40:35 PM
The spitfire seems to have an excellent glide ratio:

"The spit has an excellent glide ratio when it's clean"

http://books.google.com/books?id=RpbViiWdx7YC&pg=PT134&lpg=PT134&dq=spitfire+glide+ratio&source=bl&ots=T6TEbWm3DZ&sig=7k7IqMniTybbug9NarSlxPUBGKo&hl=en&sa=X&ei=BNFNU6XNJY_ksAT_l4G4Aw&ved=0CEgQ6AEwBA#v=onepage&q=spitfire%20glide%20ratio&f=false

Although I have no idea what an excellent glide ratio is. :headscratch:
Title: Re: Dynamic Soaring
Post by: mechanic on April 15, 2014, 07:46:05 PM
I have done this offline years ago around shallow hills and valleys. It is not sustainable for too long but can be a lot of fun. I did it with the lowest wind layer right over the tree tops
Title: Re: Dynamic Soaring
Post by: FLS on April 15, 2014, 07:47:38 PM
The spitfire seems to have an excellent glide ratio:

"The spit has an excellent glide ratio when it's clean"

Although I have no idea what an excellent glide ratio is. :headscratch:

In this case the relative quality of excellent is well short of the glide ratio of seabirds and sailplanes. It's likely the Spitfire was being compared to contemporary fighter aircraft.
Title: Re: Dynamic Soaring
Post by: Midway on April 15, 2014, 07:54:32 PM
I have done this offline years ago around shallow hills and valleys. It is not sustainable for too long but can be a lot of fun. I did it with the lowest wind layer right over the tree tops

I'll try it.  I think it would be really cool with the new water modeling if we can have large ocean swells.

From my little bit of web research it looks like the Spitfire has a glide ratio around 15 vs sailplanes around 30.  So that doesn't seem that bad relatively speaking.  So I'm guessing the wind speed would need to be doubled?  30 to 60 knot winds and we're dynamic soaring?

I have no idea what I'm talking about with respect to the aeronautical engineering math, am just guessing, but I hope someone that is an engineer would comment on it and what the windspeed impact is of the difference in glide ratio between a sail plane, albatross, and a Spitfire... or whatever aeroplane has the best glide ratio in Aces High.
Title: Re: Dynamic Soaring
Post by: FLS on April 15, 2014, 08:01:05 PM
I don't think you need much math. If the wind is 30 MPH and you lose 30 MPH on your turn then you won't gain energy.
You are also losing energy because you're gliding.  Start with a gliding turn, no wind, and look at your speed loss.
That's your guide for setting your wind layer speed.
Title: Re: Dynamic Soaring
Post by: Midway on April 15, 2014, 08:03:28 PM
I don't think you need much math. If the wind is 30 MPH and you lose 30 MPH on your turn then you won't gain energy.
You are also losing energy because you're gliding.  Start with a gliding turn, no wind, and look at your speed loss.
That's your guide for setting your wind layer speed.

I wonder if real pilots tried it in WWII when they ran out of fuel to make it home (or closer to home).
Title: Re: Dynamic Soaring
Post by: Midway on April 15, 2014, 08:08:14 PM
Apparently we can only have one wind speed for 0 - 2,000 ft altitude.  I'll have to find a spot that is 1,900 ft above sea level... or try it at the 2,000 ft level.

Ergo my wish should be restated to enable more variability in winds near the surface.


I just tried it at the 2,000 ft boundary layer.  Hard to tell anything since I'm too far above ground.  We need a zero wind at 0-50 ft, maybe 20 knots at 50-100 ft, and 60 knots above 100 ft.

I think you have to be close to a surface to have a good sense of motion and progress.
Title: Re: Dynamic Soaring
Post by: FLS on April 15, 2014, 08:54:21 PM
You should see a speed increase as you drop into the still air.  You'll want to watch your compass, altimeter, and speedometer. It might be easier with film.
Title: Re: Dynamic Soaring
Post by: Midway on April 15, 2014, 10:21:54 PM
You should see a speed increase as you drop into the still air.  You'll want to watch your compass, altimeter, and speedometer. It might be easier with film.

I see the instruments moving, but I think to really enjoy it you'd have to be very near the surface or ocean waves. I'll try it in FSX tomorrow, although not sure if I can set the wind up right there either. It needs to be fun and if you're skimming across a surface I think it would be great fun to see how far you can make it.

Fun is important.  :old:
Title: Re: Dynamic Soaring
Post by: Midway on April 16, 2014, 02:48:13 PM
22:1 glide ratio for the Albatross.

http://www.wavetrain.net/news-a-views/235-tacking-upwind-how-an-albatross-flies-to-windward

vs 15.3:1 for the Spitfire

http://forum.flightgear.org/viewtopic.php?f=4&t=6797&start=45


An excellent glide ratio indeed. :old:
Title: Re: Dynamic Soaring
Post by: FLOOB on April 16, 2014, 04:00:55 PM
If you adjust the wind settings you can takeoff without starting your motor, even in a pt boat. It may be different now, dunno.
Title: Re: Dynamic Soaring
Post by: F77 on April 16, 2014, 06:03:53 PM
A little off topic but I've glided home on numerous occassions... even glided a set of B24's a sector to land, thankfully a handy valley opened up on finals and I was able to drop in to it!