HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Oct 30, 2014, 04:55 AM
Wanna be DLG flyer
Australia, VIC, Melbourne
Joined Oct 2014
33 Posts
Build Log
The story of a dlg ( WIP blog )

Welcome!
This is going to be a design / build log of my own design ( mostly ) hlg/dlg.

What am i trying to build?
I want to build a 40" / 1M wingspan balsa/plastic dlg
I am going to be using mostly balsa wood and 3D printed parts.
( Say what you will about 3d printed parts but i have never had them break on me unless i really stress the part )

How am i going to do this?
To start i build a crude foam glider just test the idea.
Admittedly it fell apart once it hit a tree, But i learned some things from it.
1. I make ailerons way to small
2. I need to be more precise with making control surfaces
3. Hot glue is not the best glue in the world ( Didnt i already know that one?)


Right now i am very early in the design process.
At the moment i am using tail fin designs from the 40" Depron Dynamite.
I will probably refine them to suit me better.
http://www.rcgroups.com/forums/showthread.php?t=614246


I Plan to design the front pod to suit some parts i have found around the workshop.
Some of the parts i plan to use.

2c 300mah lipo and a small bec for the receiver pack. ( need to buy a bec ( any recommendations are welcome ))
HXT 900 9gram servos, you know those hobby king ones that everyone has.
4ch micro receiver ( HK orange series )
8mm dowel as the boom, yes it will have external mounted control rods ( probably not the best choice (might change to carbon fiber later on ))
A variety of balsa woods and PLA filament for the 3D printed parts.

If you guys have any design ideas or tips feel free to let me know.

Thanks for reading.
-StormPegy

P.S Updates to come every day or two.
P.P.S Are there any important factors i should take in to account when designing the wing ( Certain airfoils ect )
StormPegy is online now Find More Posts by StormPegy
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 30, 2014, 08:11 AM
Registered User
Joined Jan 2008
4,600 Posts
Storm:

I get to fly with Doug several times a year. He is a very talented fellow.

Suggestions: consider rudder/elevator, rather than ailerons (saves the weight of two servos). See the "Elf" at www.kennedycomposites.com Weight is everything, all the time. External control rods to the tail are just fine - many high-end sailplanes do it that way. A carbon tube for the boom will be stronger AND save weight (weight is everything... oh, I said that already).

Look for a regulator, rather than a BEC. There is a regulator here in the States available through Soaring USA: http://www.soaringusa.com/Battery-Re...o-for-DLG.html The smallest BEC I've found is 10g, the regulator is about 2g. Lighter is better.

Having seen a great many fine DLGs fly great, with huge repair jobs that totally mess with the airfoil, I suggest that at the Reynolds Number this airplane will fly at, that choice of airfoil will not make much difference. Try to make sure the wing is kind of rounded at front, tapers to a reasonably sharp edge, and doesn't weigh much. There's that "W-word" again. Other folks who know these things much better than I do will argue passionately otherwise, in which case my advice is to listen to them, not me.

I get stainless steel push rods in etched teflon from RCBuilder.com. Stainless steel sounds heavy, until you realize that these push rods are 0.014" wire. In the teflon tubes, glued to the boom their entire length, they work great.

Good luck.

Yours, Greg
glidermang is offline Find More Posts by glidermang
Reply With Quote
Old Oct 30, 2014, 01:02 PM
I'm all about that bass
rdwoebke's Avatar
United States, IN, Indianapolis
Joined Feb 2004
15,324 Posts
Storm,

Check out the Apogee 40 plans with the mindset to change the tail surfaces to more like a normal DLG. There is a solid and built up wood option for the wing too.

Ryan
rdwoebke is offline Find More Posts by rdwoebke
Reply With Quote
Old Oct 30, 2014, 06:22 PM
let's FLY!
JimZinVT's Avatar
United States, VT, Castleton
Joined Dec 2007
2,307 Posts
I'd second Ryan's suggestion of looking at the Apogee plans. I've built 32" and 40" DLGs based on the Apogee airfoils (AG03 and 04) that fly very well.
Good info there on accurate shaping of solid balsa wings too.
JimZinVT is online now Find More Posts by JimZinVT
Reply With Quote
Old Oct 30, 2014, 06:34 PM
Wanna be DLG flyer
Australia, VIC, Melbourne
Joined Oct 2014
33 Posts
Thanks for the feedback Greg and Ryan.

Quote:
Originally Posted by glidermang View Post
*cut to save space *
Thank Greg
I will highly consider rudder elev, i was originally only going to go for ailerons/elevator with flapperons.

On the subject of becs, i think i would prefer a $4 bec that weights 7-10 grams over a $50 bec that weights 2.
As this is my first time venturing in to the world of underpowered gliders i would prefer save a bit of money till i get the hang of stuff.

I have heard about the apogee before, guess i will check it out.




Quote:
Originally Posted by rdwoebke View Post
Storm,

Check out the Apogee 40 plans with the mindset to change the tail surfaces to more like a normal DLG. There is a solid and built up wood option for the wing too.

Ryan
Thanks ryan i will take a look.
But what do you class as a *normal* dlg tail setup?


Quote:
Originally Posted by JimZinVT View Post
I'd second Ryan's suggestion of looking at the Apogee plans. I've built 32" and 40" DLGs based on the Apogee airfoils (AG03 and 04) that fly very well.
Good info there on accurate shaping of solid balsa wings too.
Thanks Jim.
Looks like i will be using the Apogee airfoils.

-StormPegy
StormPegy is online now Find More Posts by StormPegy
Last edited by StormPegy; Oct 31, 2014 at 12:49 AM.
Reply With Quote
Old Oct 30, 2014, 07:30 PM
rug
Matt Cook
United Kingdom, New Mills
Joined Feb 2014
183 Posts
Quote:
Originally Posted by StormPegy View Post
On the subject of becs, i think i would prefer a $4 bec that weights 7-10 grams over a $50 bec that weights 2.

<snip>

But what do you class as a *normal* dlg tail setup?
Beware of weight though. For a 40" span, you should be aiming for about 150g ready to fly. 100g and you've built an Elf - Well done ! 200g is not too bad. Much over that isn't going to float very well at all ...

As for the tails, 'normal' DLG tail has vertical and horizontal, with the vertical roughly symmetrical above and below the boom. A V tail isn't going to help you much

Matt
rug is offline Find More Posts by rug
Reply With Quote
Old Oct 30, 2014, 08:10 PM
let's FLY!
JimZinVT's Avatar
United States, VT, Castleton
Joined Dec 2007
2,307 Posts
Aileron/elevator is how I built my last 40" model. The ability to use flaps and adjust camber is nice. But rudder/elevator with string & spring linkage works well (with the right amount of wing dihedral) and is easier/quicker to build and set up. And light.

Matt's weight suggestions sound right. My 40" a/e plane weighed about 150g and flew nicely. After many repairs it weighed closer to 200g it still flew OK, but better as a light wind sloper than a thermal hunter. It's all about keeping the boom & tail light, so you don't have to put in a bunch of nose weight to balance it. A gram saved in the tail is ~3g you don't need in the nose. I've learned that by getting it wrong.
JimZinVT is online now Find More Posts by JimZinVT
Reply With Quote
Old Oct 30, 2014, 09:19 PM
It's a mere flesh wound!
Buddy Roos's Avatar
Woodstock,Ga.
Joined Jun 2004
1,144 Posts
Why not use a 1s Lipo and you won't have to use either a BEC or regulator.

I've been flying an ELF and a 40" Sparrowhawk for more that 2 years with 1s 400mah Lipos without any problems. And...the Lipos only cost $4.00 each!

After the success with the two 40" DLGs, I converted my seven 1.5meter DLGs to 1S Lipos and haven't had any problems with them either.

Buddy
Buddy Roos is offline Find More Posts by Buddy Roos
RCG Plus Member
Reply With Quote
Old Oct 30, 2014, 10:23 PM
GDSHS
MikeDobies's Avatar
United States, MI, Oxford Charter Township
Joined Jan 2014
43 Posts
I fly 1 cell in all of my dlg's. The reason one cell over two is, you have a higher power to weight ratio because it the weight of only one cell, not the redundant cell like in a 2s pack. Plus with a 2s pack you need to regulate the voltage, which there is weight gained there. So let's say you use a 2s 250mah with a regulator, you can use a 1s 500mah for less weight and theoretically double the flight time. Hope this helps.
MikeDobies is offline Find More Posts by MikeDobies
Reply With Quote
Old Oct 31, 2014, 12:48 AM
Wanna be DLG flyer
Australia, VIC, Melbourne
Joined Oct 2014
33 Posts
Quote:
Originally Posted by Buddy Roos View Post
Why not use a 1s Lipo and you won't have to use either a BEC or regulator.

I've been flying an ELF and a 40" Sparrowhawk for more that 2 years with 1s 400mah Lipos without any problems. And...the Lipos only cost $4.00 each!

After the success with the two 40" DLGs, I converted my seven 1.5meter DLGs to 1S Lipos and haven't had any problems with them either.

Buddy
Thanks for the reply mate.
So,, with a 1c lipo thats about 4.2v fully charged,, dont you need a solid 5v input voltage?
I always thought 1c was to low voltage. I guess now that i look at it, it says 3.7v min input voltage so i don't see why it wouldn't work.

Do you guys change the plugs on your 1cells to normal servo plugs?


Quote:
Originally Posted by MikeDobies View Post
I fly 1 cell in all of my dlg's. The reason one cell over two is, you have a higher power to weight ratio because it the weight of only one cell, not the redundant cell like in a 2s pack. Plus with a 2s pack you need to regulate the voltage, which there is weight gained there. So let's say you use a 2s 250mah with a regulator, you can use a 1s 500mah for less weight and theoretically double the flight time. Hope this helps.
Thanks for the comment Mike.


I guess i will order a couple of 400-500mah 1c lipos.
Would somthing like this be sutible?
http://www.hobbyking.com/hobbyking/s...ngle_Cell.html

Thanks guys
-StormPegy

Edit:
I will be using the older version of this receiver
http://www.hobbyking.com/hobbyking/s...Receiver_.html
StormPegy is online now Find More Posts by StormPegy
Last edited by StormPegy; Oct 31, 2014 at 03:02 AM.
Reply With Quote
Old Oct 31, 2014, 05:58 AM
let's FLY!
JimZinVT's Avatar
United States, VT, Castleton
Joined Dec 2007
2,307 Posts
1 cell lipo works great with those HK/Orange Rx's. I run old and new versions of that one with no problems whatsoever.
JimZinVT is online now Find More Posts by JimZinVT
Reply With Quote
Old Oct 31, 2014, 07:01 AM
GDSHS
MikeDobies's Avatar
United States, MI, Oxford Charter Township
Joined Jan 2014
43 Posts
From hk, I would suggest either

http://www.hobbyking.com/hobbyking/s...gle_Cell_.html
This one as a 1s 240mah, I forgot to mention that a i use 500mah 1s in my 1.5m dlg's. Yours will need
something smaller.

http://www.hobbyking.com/hobbyking/s...gle_Cell_.html
This is a 350mah 1s, this would probably be the largest battery I would suggest due to its Weight. If you can solder, then look at the ones which don't have the battery leads and put you own on, if you're conscious of the weight of and materials, you could get even light than the one all ready to go for a few grams less.
MikeDobies is offline Find More Posts by MikeDobies
Reply With Quote
Old Nov 02, 2014, 06:37 AM
Wanna be DLG flyer
Australia, VIC, Melbourne
Joined Oct 2014
33 Posts
Small update..

I have about 70% of the wing ribs printed.
Only one small problem,, I am doing a rudder/elevator model,, and i have not designed this wing with dihedral.
Will dihedral be vital to a rudder/elevator dlg glider?

I have also printed one half of the pod that weights a whopping 64grams,, About 100grams with the servos and receiver/battery.

I have a feeling it will be to heavy.
Probs going to have a 200ish gram AUW on the first version at the rate i'm going.


-StormPegy
StormPegy is online now Find More Posts by StormPegy
Reply With Quote
Old Nov 02, 2014, 06:54 AM
I'm all about that bass
rdwoebke's Avatar
United States, IN, Indianapolis
Joined Feb 2004
15,324 Posts
Quote:
Only one small problem,, I am doing a rudder/elevator model,, and i have not designed this wing with dihedral.
Will dihedral be vital to a rudder/elevator dlg glider?
You will need dihedral. At least 12 degrees a side.

Ryan
rdwoebke is offline Find More Posts by rdwoebke
Reply With Quote
Old Nov 02, 2014, 07:41 AM
GDSHS
MikeDobies's Avatar
United States, MI, Oxford Charter Township
Joined Jan 2014
43 Posts
Dihedral on a rudder/elevator plane, like he said, is essential if you want the plane to fly. The dihedral acts sort of like a pendulum, so the rudder makes one wing drop which, is similar to ailerons, so you can make a nice easy turn. Then the wing tries to correct by leveling out, maybe even with a bit of opposite rudder. So if you don't have dihedral, you wont have the ability to level this wings. So yes it's you need it.
MikeDobies is offline Find More Posts by MikeDobies
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Question Ideas and stories for local sources of DLG foam rdwoebke Hand Launch 3 Jan 29, 2014 03:05 PM
Wanted blog or instructions for XRAY micro dlg rcbobcat55 Aircraft - Sailplanes (FS/W) 1 Dec 13, 2013 01:24 PM
DLG war stories (or, how to cure GPS) dennymaize Hand Launch 12 Mar 06, 2005 10:15 AM