Wing Strut material

[Gjsteube]

im getting down to fabricating the wing struts.  Mr. Lenard suggest using the 3" streamlined Alum, for front; and 2" same for rear. I'm gonna use 4130 tubing, that said, is there anyone flying with un-foiled round tubeing that sees a big difference in performance? All my flying in a Champ is around 55-65mph, I'm not looking to be cursing at Vne all the time.

[MrG]

i did mine out of chrome moly - dam that has some drag, the reason was for me the cost to get it to Australia
$1200 for the 4 lengths and a mate of the importer who has the rights for it here (the shipping killed us )
i did turn it into stream line shape with some fabric and 1/4 ? tube  https://goo.gl/photos/5AgvXJ4LYmbEcBcQA

If i was in the USA its a no brainer use the streamlines alum - its a good 5+ knots gain if used,  the 2nd effect is glide ratio
i had 4.2:1 with round tubes, have not done test to see what i gained but can tell you it is very noticeable difference

the photos for wing struts are about 1/2 way down the page - made the ends out of 6061 Allow rod 
https://goo.gl/photos/wsKzDQBZyrPAkU4SA

[Gjsteube]

Am I reading that right as 4.2 to 1 on your glide ratio?

[Dan_]

i did mine out of chrome moly - dam that has some drag, the reason was for me the cost to get it to Australia
$1200 for the 4 lengths and a mate of the importer who has the rights for it here (the shipping killed us )
i did turn it into stream line shape with some fabric and 1/4 ? tube  https://goo.gl/photos/5AgvXJ4LYmbEcBcQA

If i was in the USA its a no brainer use the streamlines alum - its a good 5+ knots gain if used,  the 2nd effect is glide ratio
i had 4.2:1 with round tubes, have not done test to see what i gained but can tell you it is very noticeable difference

the photos for wing struts are about 1/2 way down the page - made the ends out of 6061 Allow rod
https://goo.gl/photos/wsKzDQBZyrPAkU4SA

The Space Shuttle is good for 4.5 on approach...  Scroll down to the listings in the tables.


https://en.wikipedia.org/wiki/Lift-to-drag_ratio

[Gjsteube]

Soooooo....4:1 being glide ratio for helicopter in auto gyration, is around 4-5 about average for the Double Eagles?

[MrG]

when i get some more time on it - i do that properly - but its distance / height 
i can tell you the space shuttle is probably better than a DE but we do beat the House Sparrow 
I got a program on my phone now that will record distact traveled and give to me in a KLM file
to put into google maps and can work it out better

[Dan_]

In your example in the other thread, you have to get miles per hour or KN into feet per minute. 


48 miles per hour is 4224 feet per minute. 


Divide 4224 fpm by 860 fpm and the fpm unit is cancelled, so that you are left with a ratio, 4.9 in the example below.

See attached for unit conversion...


GJ and Tom, went up last night and did a engine off glide back into the airport from 3000ft agl (dead stick landing)
60 knts / 70mph is about 1050 fpm +
50 knts / 60 mph is about 900 fpm
42 knts / 48mph is about 860 fpm
thou my wings are a tad shorter, as for glide ratio form the first experience i had was somewhere around 4:1 to 4.25:1 from what we can work out for the video
even thou i did do a heap of drag stuff since then (wing struts and jury struts) - i have more to do

[MrG]

@Dan wow good maths - did not think of doing it that way
Looks like what im doing is / has gain some glide angle, closed in the gear legs today - have see how that goes

[Darren C]

Hey Grant.
 
Got some pics of your closed in gear legs and how you did it?

Do you plan to streamline your struts?  I'd always thought foam and fiberglass was a good option.

I'd be keen to hear your thoughts.

Cheers
Darren.

[Dan_]

@Dan wow good maths - did not think of doing it that way
Looks like what im doing is / has gain some glide angle, closed in the gear legs today - have see how that goes

You could also note your altitude and fly a known distance, perhaps the length of a runway.    

Then you would divide the distance forward by the distance down, so no unit conversion to do.  

Possibly more accurate than the VSI method as well.  

Wind will affect usefulness of your results of course.

There are formulas to get distance between to GPS coordinates as well.

Spreadsheet attached...  Enter numbers in the shaded cells.

[Dan_]

@Dan wow good maths - did not think of doing it that way
Looks like what im doing is / has gain some glide angle, closed in the gear legs today - have see how that goes

Spreadsheet attached...  Enter numbers in the shaded cells.

I fixed a typo in the Spreadsheet.  I had "start lat/long"  twice instead of start and end lat/long.

Also I added a note about a factor you could use to get feet/minute from miles/hour on your calculator very quickly.

[MrG]

Hey Darren 
yes always planed to close in gear and streamline the struts - Matt at performance metals has the rights to the strut material her so unless
you can get some one to buy it and ship it for you its big $$$$ 

Wing Struts -  I welded on a 1/4 (4mm) ? chrome molly tube with stand offs (about every 600mm and same material) then just fabriced it.
 (cant find photo with just the tube)

With the gear legs I just fabricked them (Canter gear legs design) would do exactly the same if i did another
on all jury and the landing gear tubes under the plane were done with balsa wood and fabricked works really well and light weight
reason i did main struts with the tube was its stronger and if the balsa wood was banged it would of got damaged

All fabrick work is done with the experimental fabric and the Steward system http://www.stewartsystems.aero/default.aspx  
its that easy my daughter does it too - i just order it all from Spruce, the guys in melbourne stopped selling fabric in Jan.
they have all there videos how to do on you tube 
You always welcome to come up and have a look - another 10 hrs i can take you for a fly 

-- Ill check that out Dan

[Darren C]

Great photos Grant.  Thanks for that.
I am going to get mine finished and then make changes here and there noting performance variations as I go along.  A bit like yourself.  
On a previous build I fell into the trap of making all kinds of 'improvements' to the original plans and the build time blew out to about double which was crazy!

Do you use the Gennipod to charge your battery?  Does it work well?

Have seen your latest vid.  The new engine is going well for you.

I'll make the time and come up when you are ready.  It's about a 6 hour drive to Temora so will make a weekend of it. 

Am in Bali at the moment and still log in each morning to see how the Eaglersnest is going.  Don't want to rub it in though.  haha

Cheers mate.

[MrG]

Hey Darren 
i was just in (at) Wadigi Island  http://wadigi.com :-)  got 30hrs up now all going good - the genipod if i fly it longer than 30 min and i have long taxi ways
i can nearly get away with out adding the charger, for about 6 flights - as some have been small hops laterly i have had to charge it today ready for next flight
I have a Microair radio voltage gagde (led) and a set of points with coil (bosch blue) - very happy with it.  As i start longer flights 40 min or more should be OK
mine does start pretty good to so not loosing a lot on crank
only thing i found if i have 11.2 volts and then when cranking i get down to 6v ?  it wont fire the spark plugs, i do have a fair bit of compression thou as well
that does not help - always welcome up here - hope when this big weather front goes through i can bang the next 10 hrs out pretty quick - then i can take people up