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Old Apr 05, 2012, 09:11 AM
Gary
gklein's Avatar
USA, CT, Sandy Hook
Joined Dec 2009
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Build Log
Sperry Messenger - Now with video!

Working on my newest project. My goal is to make a small brushless plane, with servos not actuators. This will not be a record setting plane by any stretch, just my own personal best for size given my abilities and off the shelf components while still maintaining good flight characteristics. In the past I converted a Gravity Hobby free flight Zero to brushless rc and made a slightly impractical bullet (http://www.rcgroups.com/forums/showthread.php?t=1396726) and did not want to repeat that experience! This time I have selected the Sperry Messenger for reason of the two squared-off wings with equal spans to maximize the wing area, and because I like it. I am targeting an 11 inch wing span (because 10 inch just looked too damn small!) and construction material will be 1mm Depron. I know that I can make a lawn dart and go smaller but I would prefer a more reasonable flight dynamic for indoor. Build will be from an old Walt Mooney peanut plan and the three-view of a Messenger.
It was really the introduction of the SuperMicro radio line from HK that piqued my interest in making this size plane. I already have the tx module and the brick (http://www.hobbyking.com/hobbyking/s..._one_5ch_.html). I have bench tested the servos but have not yet attached a motor. As you can see it has a 3.5 amp brushless controller on the brick and one of the attractions in my mind after my prior experience is the skinny long layout. Only 7.8mm wide and perfect to fit in small narrow fuselages.

Motor choice: I am undecided between the AP-02 or the Hextronic 2 gram for this one cell application.

http://www.hobbyking.com/hobbyking/s...tor_2_3g_.html

http://www.hobbyking.com/hobbyking/s...er_7700kv.html

Oh and the plane will be RET. I see no good reason for the extra weight of ailerons on this one. The target weight is 28 grams.
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Old Apr 05, 2012, 10:14 AM
Gary
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USA, CT, Sandy Hook
Joined Dec 2009
810 Posts
I started with the wings. Not being satisfied with my prior forming of wings, too inconsistent. This time I quickly shaped a balsa plank into an airfoil shape laid it in the bottom of a tall sided cooking pan, placed the foam over it, laid a sheet of tinfoil over that and then poured in several pounds of sand and threw it in the oven. Twenty minutes at 200F and I had my airfoil shape. Next I cut them out and put a grinding wheel from my dremel in a drill press for the scallops.

Next time I will raise the balsa form slightly off the bottom of the pan and get a better form at the leading edge.
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Old Apr 05, 2012, 10:44 AM
Gravity is a harsh mistress.
Tim Wolff's Avatar
United States, MI, Temperance
Joined Sep 2002
6,555 Posts
The Mooney plans are a great source. His Peanuts are known good fliers.
It pains me that it is done in foam rather than balsa and tissue, but I understand the reasons builders do so. The sand is a great idea. I've never heat formed foam because I didn't want to make the molds.

I've tried a number of single cell brushless motors. Most of them draw way too much current and deliver too little power. The AP-02 and 2g motors can cope only with rather smallish props. I have both motors, but have yet to try them in anything. Given the results I've had with both winds of the AP-03, AP-05, and AD-C5, I'd suggest checking into the the lower kv AP-03 and a 4" prop. It is adequate power for my 30.6 g DH-2 on a Thunder Power 160 mA cell.

Others have reported that the cheap single cell brushless controllers fail to deliver all the potential power due to the use of cheap FETs. I've obtained a quantity of quality FETs and plan on replacing the stock FETs on my ESCs and see if it makes a difference.

Keep the pics coming too!
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Old Apr 05, 2012, 11:31 AM
Gary
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USA, CT, Sandy Hook
Joined Dec 2009
810 Posts
Quote:
Originally Posted by Tim Wolff View Post
The Mooney plans are a great source. His Peanuts are known good fliers.
It pains me that it is done in foam rather than balsa and tissue, but I understand the reasons builders do so. The sand is a great idea. I've never heat formed foam because I didn't want to make the molds.

I've tried a number of single cell brushless motors. Most of them draw way too much current and deliver too little power. The AP-02 and 2g motors can cope only with rather smallish props. I have both motors, but have yet to try them in anything. Given the results I've had with both winds of the AP-03, AP-05, and AD-C5, I'd suggest checking into the the lower kv AP-03 and a 4" prop. It is adequate power for my 30.6 g DH-2 on a Thunder Power 160 mA cell.

Others have reported that the cheap single cell brushless controllers fail to deliver all the potential power due to the use of cheap FETs. I've obtained a quantity of quality FETs and plan on replacing the stock FETs on my ESCs and see if it makes a difference.

Keep the pics coming too!
I'm jealous of the fact that you can handle changing out FET's! You are correct on the other motors. I have also used both AP-03's and the '05. But I have used (briefly) the 2gram and want to work them some more. Maybe I'll change back but that's my plan for the moment.

I also build with sticks (see photo - has the AP-03 in it) but have been on a foam kick for the last year. The foam models are much more durable indoors with the attendant mishaps. But I'm getting itchy - the next model I might have to breath some balsa dust!
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Last edited by gklein; Apr 05, 2012 at 01:21 PM.
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Old Apr 05, 2012, 02:06 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
6,430 Posts
Quote:
Originally Posted by Tim Wolff View Post
I've tried a number of single cell brushless motors. Most of them draw way too much current and deliver too little power. The AP-02 and 2g motors can cope only with rather smallish props. I have both motors, but have yet to try them in anything. Given the results I've had with both winds of the AP-03, AP-05, and AD-C5, I'd suggest checking into the the lower kv AP-03 and a 4" prop. It is adequate power for my 30.6 g DH-2 on a Thunder Power 160 mA cell.

Others have reported that the cheap single cell brushless controllers fail to deliver all the potential power due to the use of cheap FETs. I've obtained a quantity of quality FETs and plan on replacing the stock FETs on my ESCs and see if it makes a difference.
Tim,
What you say about drawing too many amps is true primarily of the Chinese 1-cell BL motors. It is not true about the Mighty Midget or Gasparin motors. I have used two of the G10 Gasparin BL motors on two different planes and they have a nice tradeoff between amp draw and thrust. And, in terms of BL controllers I use the non-Chinese controllers as well for the reasons you mention.

It's not an issue of 1-cell BL motors. It's a case of you get what you pay for. The appropriate wind is needed, higher quality magnet wire (results in more efficiency), a tight wind with lots of copper filling the space, and a good BL controller with high quality FET's. With the right combination that has all those characteristics a 1-cell BL setup can perform nicely.

For example, years ago the owner of Mighty Midget told me he decided not to use substantially cheaper magnet wire from China because of the difference it made in terms of efficiency. Instead he went with more expensive magnet wire from elsewhere to get better efficiency.

Personally, I tend to pay up for motors that I don't have to rewind, and BL controllers that I don't have to replace FET's. But, that's my perspective.

Everything you say is true about most of the Chinese motors and BL controllers. No dispute there.


Gordon
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Last edited by Gordon Johnson; Apr 05, 2012 at 02:13 PM.
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Old Apr 05, 2012, 02:14 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
6,430 Posts
Gary,
Very nice choice for your project. I also like your sand technique.

Gordon
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Old Apr 05, 2012, 05:09 PM
Gary
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USA, CT, Sandy Hook
Joined Dec 2009
810 Posts
Thanks Gordon!
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Old Apr 05, 2012, 09:11 PM
Gary
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USA, CT, Sandy Hook
Joined Dec 2009
810 Posts
Fuselage, fairly standard construction. Depron sheet construction and I prefer using dollar tree foam for bulkheads and spacers. It provides a larger glue surface and greater rigidity to the structure without adding weight over the depron. Cut the tail surfaces and attached. The third picture shows the planned location for the rx brick.
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Old Apr 09, 2012, 08:36 PM
Gary
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USA, CT, Sandy Hook
Joined Dec 2009
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O.K. going slow. I struggled some with the front top to the fuselage. Don't tell anyone but I redid it four times till I was tired of working on it, but at least got it to acceptable. Went with the AP-02 motor and built the cowl up around it from dollar tree foam. I temporarily connected the motor to the receiver to make certain that it would fire up. It ran well but the throttle does not start till half stick. This is a programming issue that I had once before and will need to remember how I fixed it. But not a show stopper. I only had the motor in my hand with a 0302 prop on it but if felt o.k..

The struts were made of bamboo from a home depot bamboo window shade. The radio access I changed to the bottom. (one of my four changes) I will install a 1mm seperator between the radio and the battery.

Haven't even thought about the landing gear mounting yet if you can believe that. At the moment the fuselage weighs 7 grams, but that is with the 2.3 gram motor, making it 4.7 grams without. I think that I am still not too bad on weight. But I know that the landing gear, wheels, radio installation, and paint are yet to come.

Of course the last two pictures are positioning the wings so that I can make the traditional airplane noises! Note that the rudder and elevator are not in-place yet.
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Last edited by gklein; Apr 09, 2012 at 08:55 PM.
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Old Apr 09, 2012, 09:04 PM
4000 posts?!
micro_builder's Avatar
United States, TX, Fort Worth
Joined Jan 2005
4,045 Posts
I dont know how some of you guys make foam work for you so well...unless its a flat sheet, me and foam rarely get along. Your sand molding technique is a good idea though, is the form permanent or does it eventually flatten out over time?

Looks good!

Nick
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Old Apr 09, 2012, 10:07 PM
Gary
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USA, CT, Sandy Hook
Joined Dec 2009
810 Posts
Quote:
Originally Posted by micro_builder View Post
I dont know how some of you guys make foam work for you so well...unless its a flat sheet, me and foam rarely get along. Your sand molding technique is a good idea though, is the form permanent or does it eventually flatten out over time?

Looks good!

Nick
Thanks Nick.

The forming should be permanent at the temperature used. I did place two ribs underneath each panel - but that is as much for rigidity as shape.
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Old Apr 10, 2012, 10:34 PM
Gary
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USA, CT, Sandy Hook
Joined Dec 2009
810 Posts
Added a plug to the end of the supermicro brick. Very easy even for my limited skills. Used this plug (same as is on the spektrum 6400):

http://www.rc-connectors.com/index.p...h752eo3jvmhj16

Bent the legs to match the holes and a few minutes later - done. The plug is so barely heavier than the wire.

Also you can see from the pictures one of the reasons that I am trying this gear.
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Old Apr 12, 2012, 12:38 PM
Registered User
West of California Speedway, East of LaLa, North of Disneyland
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Quote:
Originally Posted by Tim Wolff View Post
The Mooney plans are a great source. His Peanuts are known good fliers.................................. I'd suggest checking into the the lower kv AP-03 and a 4" prop. It is adequate power for my 30.6 g DH-2 on a Thunder Power 160 mA cell.
Ditto for me !!

....and the TP 160's beat the Hyperions.........
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Last edited by 356Jim; Apr 12, 2012 at 01:22 PM.
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Old Apr 12, 2012, 09:52 PM
Gary
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USA, CT, Sandy Hook
Joined Dec 2009
810 Posts
Told you I build slow.....spent the evening building wheels. Made them out of o-rings, depron, plastic tube for the hub. Used my trusty dremel like a lathe, held depron on the dremel with the arbor from my cut-off disks. Sand paper made quick work of it. Three disks, one inner to fit the o-ring on, and two outers - slightly larger dia. to make the sides. Sanded and tapered one face for the outer surface. My target weight was 2 grams and I ended up at 1.5 grams for the pair. The scale wheels had a larger tire portion but I did not want to add that weight. I hope that it will not look to bad on the plane.

Last night I installed the radio and hooked up the control surfaces. The wings are still not attached although I put them in place for the picture.
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Last edited by gklein; Apr 12, 2012 at 10:01 PM.
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Old Apr 13, 2012, 02:46 PM
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United States, CO, Westminster
Joined Jul 2011
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Very nice
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