HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Apr 19, 2012, 12:40 AM
Wid
Live Your Dreams
Wid's Avatar
United States, CA, Redwood Valley
Joined May 2001
602 Posts
Discussion
Which sub micro servos for 2 meter sail planes?

The Allegro lite 2 meter sail plane designed by MIT Professor Mark Drela can take full pedal winch launches, over 100 lb tension on the winch line! JR 241 sub micro servos are recommended for this plane and used by many. I have had botched landings that ripped off the tail but not damaged the 241. This makes me think these and other sub micro servos would be suitable for just about any 2 meter sail plane as long as similar low friction push rods are used. At 9 grams each there is a substantial weight saving over larger servos. Am I missing something?

Now that the JR 241's are no longer manufactured what would be the recommended replacement? I have heard of the JR s22 but wonder if the "JR sport line" quality is the same as good as the 241. I'll probably stick with analog rather than digital.

Any experience with these and similar servos in these applications?

P.S. A short video of a hand launch of the Allegro in very marginal conditions can be seen here.
Wid is online now Find More Posts by Wid
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 13, 2012, 05:28 PM
Registered User
Joined Jun 2012
10 Posts
Im very happy to find you.

Im going to explain why. I have made an electric Allegro lite, and when I was looking for colours of the cover, I saw your Allegro in youtube, in this vid you have posted.

And I have decorated in the same way than yours! I like it very much.



Talking about servos, I am using Dymond D47
21,6 x 8,0 x 17,8 mm
weight: 4,7 grs.
1,1 Kg/cm a 4,8v.
Here can you see them:




I have no problems with them, and they are very light.


In spoiler Im using Hitec Hs65hb.


Sorry for my english.. I know is not very good.
alioth is offline Find More Posts by alioth
Reply With Quote
Old Jun 14, 2012, 03:14 AM
Registered User
Graham 65's Avatar
Chipping Norton, UK
Joined Jul 2006
393 Posts
Very nice plane, congratulations!

What is the flying weight?
What motor and battery are you using?
Graham 65 is online now Find More Posts by Graham 65
Reply With Quote
Old Jun 14, 2012, 04:24 AM
Registered User
Joined Jun 2012
10 Posts
Thanks!

Engine Axi 2217/16
Batt lipo 1200 3s (I would prefer a small one or 1200 2s with 12x6", but need this 100g batt to balance)
prop 10x6" which supose 18A.. so near 200W. Goes up vertical.
Flying weight is 680g. (24oz)

Is a little heavy. I am thinking to make another Allegro e-Lite, with a lighter and smooth power system, to end it in 560-580g
Im thinking in Axi 2212/34 + CC Phoenix 10 and lipo 700 3S, and a lighter boom and pushrods (or dymonds d47 into rudder).
It would be 10A.. 100W... and Im not sure if it would be enough. I want at least 180-200m in 30seconds.

Yesterday I got my first Hand Launch thermal in my life with this baby!
Im very very happy with it!!
and thanks to Mark Drela for those desings.
alioth is offline Find More Posts by alioth
Reply With Quote
Old Jun 14, 2012, 07:05 AM
Chuck 'Em and Chase 'Em
Fly2High's Avatar
United States, NY, Plainview
Joined Aug 2005
8,116 Posts
Jr D285 or the JR SM22.

Many in the hand launch community either love or hate the Dymond D47 b/c some say it drifts due to heat. Also, the gears are not that strong. Some have stripped them out.

The Jr servos have a finer accuracy as well.

Frank
Fly2High is offline Find More Posts by Fly2High
Reply With Quote
Old Jun 14, 2012, 04:52 PM
Registered User
diogen151's Avatar
Hill under Mountain
Joined Mar 2007
66 Posts
1. Dymond d47
2. Blue Arrow D05010MG (they are 1,2 kg, not 0,61 !)
3. GWS Pico F/BB 6,2 gr
4. GWS Naro HP BB

And here are my gliders fitted with this servos...




Diogen
diogen151 is offline Find More Posts by diogen151
Reply With Quote
Old Jun 14, 2012, 05:57 PM
Wid
Live Your Dreams
Wid's Avatar
United States, CA, Redwood Valley
Joined May 2001
602 Posts
Allegro Lite

Quote:
Originally Posted by alioth View Post
Im very happy to find you.

Im going to explain why. I have made an electric Allegro lite, and when I was looking for colours of the cover, I saw your Allegro in youtube, in this vid you have posted.

And I have decorated in the same way than yours! I like it very much.

Talking about servos, I am using Dymond D47
21,6 x 8,0 x 17,8 mm
weight: 4,7 grs.
1,1 Kg/cm a 4,8v.
<snip>
I have no problems with them, and they are very light.


In spoiler Im using Hitec Hs65hb.
<Snip>

Sorry for my english.. I know is not very good.
Great to hear from you. Beautiful plane! and and isn't the Allegro Lite a FANTASTIC plane?

At some point I will add white wing tips on the underside for increased visibility.

Thanks for the servo info. I am now building an electric fuse for my Allegro wing. Finally have all I need, I think. Except maybe time?

Your English is clear and very understandable. More than I can say for some of the locals (no offense intended guys) Since you love Allegro Lite you will probably enjoy

Allegro lite thermals with vulture (2 min 21 sec)
Wid is online now Find More Posts by Wid
Reply With Quote
Old Jun 14, 2012, 06:13 PM
Wid
Live Your Dreams
Wid's Avatar
United States, CA, Redwood Valley
Joined May 2001
602 Posts
Quote:
Originally Posted by Fly2High View Post
Jr D285 or the JR SM22.

Many in the hand launch community either love or hate the Dymond D47 b/c some say it drifts due to heat. Also, the gears are not that strong. Some have stripped them out.

The Jr servos have a finer accuracy as well.

Frank
Thanks Frank. I ran into that observation over at the Allegro Lite group as well.
Wid is online now Find More Posts by Wid
Reply With Quote
Old Jun 14, 2012, 06:20 PM
Wid
Live Your Dreams
Wid's Avatar
United States, CA, Redwood Valley
Joined May 2001
602 Posts
Quote:
Originally Posted by diogen151 View Post
1. Dymond d47
2. Blue Arrow D05010MG (they are 1,2 kg, not 0,61 !)
3. GWS Pico F/BB 6,2 gr
4. GWS Naro HP BB

Diogen
Thanks for the info. You are Lucky man to share your flying so well. Nice fleet of planes too. Gotta love the way those long wings fly.
Wid is online now Find More Posts by Wid
Reply With Quote
Old Jun 16, 2012, 12:32 PM
Registered User
Joined Jun 2012
10 Posts
Quote:
Originally Posted by Wid View Post
Great to hear from you. Beautiful plane! and and isn't the Allegro Lite a FANTASTIC plane?

At some point I will add white wing tips on the underside for increased visibility.

Thanks for the servo info. I am now building an electric fuse for my Allegro wing. Finally have all I need, I think. Except maybe time?

Your English is clear and very understandable. More than I can say for some of the locals (no offense intended guys) Since you love Allegro Lite you will probably enjoy

http://www.youtube.com/watch?v=W9ysloBNSic&feature=plcp

Very beautiful flying. Allegro is the most beautiful soaring machine. Im going to record some vids from mine and I will post them here. Im in love with the Allegro.
alioth is offline Find More Posts by alioth
Reply With Quote
Old Jun 16, 2012, 04:49 PM
Registered User
diogen151's Avatar
Hill under Mountain
Joined Mar 2007
66 Posts
Quote:
Originally Posted by alioth View Post
Very beautiful flying. Allegro is the most beautiful soaring machine. Im going to record some vids from mine and I will post them here. Im in love with the Allegro.
Allegro is fantastic glider, but at 680 gr it is overweighted. I have some experience with Allegro, best way to make it better is to build lighter fuselage (tailboom !!!) and use lighter battery at opposite side.
Look at second picture in my previous post: solo glider at picture is 'Kmica': 1,96 m wingspan with 29 dm2 area: at only 353 gr AUW it is only 12,2 gr/dm2 . --> http://web.vip.hr/385915861879.vip/Kmica_Kmica.jpg
You can catch the lightest thermal, full carbon d-box provides many advantages over balsa D-box: very light and extremly strong !
Wish you thermals !
Diogen
diogen151 is offline Find More Posts by diogen151
Reply With Quote
Old Jun 17, 2012, 12:00 AM
Wid
Live Your Dreams
Wid's Avatar
United States, CA, Redwood Valley
Joined May 2001
602 Posts
Quote:
Originally Posted by diogen151 View Post
Allegro is fantastic glider, but at 680 gr it is overweighted. I have some experience with Allegro, best way to make it better is to build lighter fuselage (tailboom !!!) and use lighter battery at opposite side.
Look at second picture in my previous post: solo glider at picture is 'Kmica': 1,96 m wingspan with 29 dm2 area: at only 353 gr AUW it is only 12,2 gr/dm2 . --> http://web.vip.hr/385915861879.vip/Kmica_Kmica.jpg
You can catch the lightest thermal, full carbon d-box provides many advantages over balsa D-box: very light and extremly strong !
Wish you thermals !
Diogen
Yep. That is the one I called the long wing. That is really light for a 2 meter. Kits? Plans?

My allegro is about 19oz depending on how far back I push the balance point. I have to work on lightening my tails for weight reduction. Almost 2oz nose ballast required now. I'd like to build 200gr lighter!

353 gr includes power system! I want to know more.
Wid is online now Find More Posts by Wid
Last edited by Wid; Jun 17, 2012 at 12:06 AM. Reason: 353 gr includes power system!
Reply With Quote
Old Jun 17, 2012, 08:23 AM
Registered User
diogen151's Avatar
Hill under Mountain
Joined Mar 2007
66 Posts
Quote:
Originally Posted by Wid View Post
353 gr includes power system! I want to know more.
This glider was built for Croatian national category for electric glider F5J-N,
specs are:
-min. weight: 350 gr; min. wing load: 12 gr/dm2; brushed motor class 400 6 V (Speed 400), direct drive 6*3 folding prop. (Graupner, AeroNaut, Robbe), 2S LiPo battery (usually 1000 mAh) only 2 servos (no ailerons !).
We wanted to do it so simple and cheap.
Competition: 30 sec motor drive and 10 minutes of working time, landing in point for extra points.
8 rounds, 7 best taken for score and no fly-offs.
Diogen
diogen151 is offline Find More Posts by diogen151
Reply With Quote
Old Jun 22, 2012, 12:21 AM
Wid
Live Your Dreams
Wid's Avatar
United States, CA, Redwood Valley
Joined May 2001
602 Posts
Quote:
Originally Posted by diogen151 View Post
This glider was built for Croatian national category for electric glider F5J-N,
specs are:
-min. weight: 350 gr; min. wing load: 12 gr/dm2; brushed motor class 400 6 V (Speed 400), direct drive 6*3 folding prop. (Graupner, AeroNaut, Robbe), 2S LiPo battery (usually 1000 mAh) only 2 servos (no ailerons !).
We wanted to do it so simple and cheap.
Competition: 30 sec motor drive and 10 minutes of working time, landing in point for extra points.
8 rounds, 7 best taken for score and no fly-offs.
Diogen
The most significant decrease in weight available in the Allegro design seems to me is the D box construction. Is most of the weight savings in the your open rib wing?
Wid is online now Find More Posts by Wid
Reply With Quote
Old Jun 23, 2012, 04:41 AM
Registered User
diogen151's Avatar
Hill under Mountain
Joined Mar 2007
66 Posts
Quote:
Originally Posted by Wid View Post
The most significant decrease in weight available in the Allegro design seems to me is the D box construction. Is most of the weight savings in the your open rib wing?
It is not possible to loss all surplus weight in only one constructive point: more substantial is approach to loss weight in every possible position.
And not to weaken construction !
For example covering: all self-adhesive coverings are no less than 35-40 gr/ m2.
For 30 dm2 wings you need approx. 0,6 m2 i.e. you add more than 20 gr to construction. We use Oracover Air Indoor which is 20 gr /m2. This covering is not self-adhesive an special glue is needed. We usually mix neoprene-glue with special thinner and place it only where glue for covering is needed.

Best weight to strenght ratio have carbon d-box: spars are made with carbon 1 mm strips (up and down) and with vertical balsa ('shear webs') between them.
Balsa strips and carbon spars need to be wrapped with kevlar rowing for reliability .

I need about 3 years to lower AUW form 400 gr to 350 gr , which can be seen in this table (all model are at picture in my first post in this topic)
Wish you thermals

Diogen
diogen151 is offline Find More Posts by diogen151
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold Servos, servos, servos. Hitec HS-55s + other micros/sub-micros jgalexander Aircraft - General - Radio Equipment (FS/W) 8 Nov 21, 2011 09:04 PM
Sold Sub Micro 2.5g Servo NEW Unused with JR Connector ShokWaveRider Aircraft - Electric - Micro & Indoor Airplanes (FS/W) 0 Nov 13, 2011 09:06 AM
Looking for good 2 meter Sail plane Sheptack Sailplane Talk 4 Oct 05, 2004 05:58 AM
2 Meter Electric Sail plane Sarj Electric Sailplanes 15 Jul 31, 2003 04:37 PM