Glide Ratio

[valmee]

Hi, everyone!
The Aviat A-1B Husky (I am a bush pilot...) and the Douglas DC-3 are my fave birds. I got curious about their glide ratio and made this experiment.

Please, consider this question:

A Douglas DC-3 and an Aviat A-1B Husky fly together, side by side, at FL080. There isn"t any obstacle ahead, only loooong plains. If the engines of both aircrafts were turned off, simultaneously, which one would touch the ground first? Why?

Best!

Valmee
AAS048
^^^^^^

[Wild Man]

G'day Mate

I reckon the Avait would touch down first.
becouse it has a smaller wing span, thus a will glide less.

Cheers
Zarik

[clmax]

Great question and once again, welcome aboard!!



Of course these real-world performance calculations may not reflect the aircraft performance in MSFS

What was your result?

-Greg

[Russ]

*Raises Hand*

Okay so .. um ..

Which is better .. a lower Emax, or a higher Emax?

[clmax]

Another good question ;D ;D

The max lift-to-drag ratio (Emax) represents how many feet the aircraft would move laterally for every foot of altitude lost.

So, higher is better in the sense of the original question.

Todays high-performance gliders have Emax in excess of 60

-Greg

[valmee]

Hi, Zarik, Greg!
Both of you hit the target! ;D

Greg, I'm a college teacher, retired. But still working on my Ph.D thesis (Linguistics)! ~~ Math? Physics? Aaaargh! heh, heh, heh.

Calculating? Far from the wonderful one of yours! I just checked the time of gliding of each airctaft. ;D The DC-3 touched the ground in second (8 sec).

Stay well!

Valmee
AAS048
^^^^^^

[Joe Deering- KA4GBC]

So Zarik was right considering the lower Emax of the A1B :-)
Although I don't believe he came to the same conclusion in the same manner :-)
I think Newton stated that all objects are pulled by gravity at the same rate, but he didn't take into his equations the effect of lift areas on the objects in relation to the density of the atmosphere which produces friction and reduces the atmospheric pressure according to the aerodynamic configuration of the lift area itself.
So, the more Emax the better :-)

[clmax]

An important point I failed to explicitly mention here is that Emax is attained at CD0. This means that to realize Emax, you must trim your aircraft to the airspeed that yields best range (which is coupled to the weight).

I don't know if that was the specific question Valmee was asking, but I tried to expand on lift-to-drag ratio.

There are two important speeds for unpowered flight; maximum range, and maximum endurance. Pilots who have an engine failure are going to trim to maximum range speed.

I would be happy to post an "Aircraft Performance Lesson" now and again if there is some interest, but I have found the numbers do not match well with MSFS and have adopted a "Test Pilot" approach to learning about aircraft performance in MSFS.

There have recently been a few cool gauges uploaded to AVSIM to help determine performance characteristics. The one that comes to mind is one that does takeoff and landing distance - COOL

Here's the name of the file: runwayroll_10.zip

-Greg

[Wild Man]

joedeer said:

So Zarik was right considering the lower Emax of the A1B :-)
Although I don't believe he came to the same conclusion in the same manner :-)

Hell NO!

I dont have any degrees in fact I can barely spell of add up. I left school at 15 because of the dyslexia.

I just used a bit of gliding knowledge I have gained over the 10 or so years I have been doing simulated flight.

I would love to get my Gliders Licensee but I am a big boy to large for most gliders.


Yup Greg I would love to learn more.

Cheers guys

( I feel like a village idiot among all you highly educated blokes.)

[Frank Seigler-KE5ETD]

Well Zarik,

I have a BA in Economics and a MBA but I felt like the village idiot when I was reading Greg's post with all the formulas. As you can tell, I was a business guy because I couldn't hack engineering.

[clmax]

Sorry guys, that certainly was not the intention!! I would have been happy to simply say, "The Aviat because it has a lower aspect ratio.", but inside every engineer is a teacher dying to get out And for some reason, I the way that "Why?" was sitting there, I just thought Valmee was looking for a detailed response.

As Zarik's post is proof of, common sense goes a long way.

-Greg

[Joe Deering- KA4GBC]

Hey Wild Man, don't feel bad, I feel the same way sometimes! These guys are so educated it makes my head swim
I have a large vocabulary so I can make things sound good! Only a few years of college (15 to be exact) but that isn't what it appears to be.
I had to go to college through the Police Dept where I worked. we had to complete a course every year or lose our jobs.
So when asked if I went to college I reply, yeah, for 15 years I have enough credits for a degree in Law Enforcement, but never got around to it.
I did learn a lot and enjoyed it!
Before that I spent 20 years in civil engineering as a designer draftsman(highways, cut and fill calculations, watershed runoff's etc) That was an interesting vocation!
Sorry about the rambling, I don't know when to stop sometimes!

[Wild Man]

Hey, I don't feel bad. ;D ;D ;D

I am very happy being house dad / photographer / digital artist / me.

I don't have to say yes or no to a boss.
I don't have to drive in rush hour traffic to get to work.

I have nappies! ;D ;D ;D ;D

And every dam little creature that likes to bite when I am trying to take a photo.

I am very happy

Cheers
Zarik ... The happy village idiot! ;D ;D ;D ;D ;D ;D ;D