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Old Dec 07, 2008, 05:26 PM
ramovan's Avatar
United States, NV, Pahrump
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Top Flite Stinson Reliant Giant Scale on Electric

Welcome everyone,

For my winter project I wanted to build a giant scale electric plane and I've always loved the unique looks and reported flying characteristics of the Stinson Reliant. I chose the Top Flite 1/5th scale Stinson Reliant kit. As far as I know no one makes an ARF of the Reliant in this size so it's going to be a 6 month project for me - since I only get an hour or two most nights to work on it.

I have seen others electrify this plane in magazine articles which will be a good reference point, but I've still rarely seen this airplane on electric power. I'm not going to get too detailed in this build log as far as the building process since others have already done this in gas versions. I'm more interested in the discussion of the main components of the plane, the electric power system, and all the other electronics used to complete the build.

I encourage everyone to chime in with your thoughts and suggestions. I want to draw on the experience of other modelers, while hopefully providing some helpful information to anyone interested in building this model as an electric.

My target flying weight in electric is 20lbs, although I suspect I'll end up closer to 22lbs depending on the covering I use.

Here are the airplanes specs and stock photos from Top Flite
Wingspan: 100.5 in (2550 mm)
Wing Area: 1487 inē (95.9 dmē)
Weight: 16-25 lb (7260-11340 g)
Wing Loading: 24.8-38.7 oz/ftē (76-118 g/dmē)
Fuselage Length: 67.8 in (1720 mm)
Requires: 4-5 channel radio with 6-8 servos, 2-stroke 1.08-1.99 cu in (17.5-32.5 cc), 4-stroke 1.2-1.6 cu in (19.5-26), or 25-35 cc (1.5-2.0 cu in) gasoline engine, glow fuel, glow starter and support equipment





Full Details here - http://www.top-flite.com/airplanes/topa0310.html
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Last edited by ramovan; Dec 07, 2008 at 06:44 PM.
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Old Dec 07, 2008, 05:50 PM
ramovan's Avatar
United States, NV, Pahrump
Joined Aug 2004
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The Power System

For the power I'll be using a Scorpion 55mm motor which are due to be released sometime in December 2008. It's going to be a while before I'm ready for the motor as there is a ton of building to do. The 55mm motors are going to be available in 3 new physical sizes, each of which will have at least two Kv models to choose from - 7 models in all. I will discuss the exact motor selection later in more detail once the motors and full specs are released.




For the ESC I plan to use the new Scorpion 12S controllers that will be coming out just before the 55mm motors are available. These will be available in 90A and 130A models. I'll choose which model I need after I know which motor I'm going to run. As with all the Scorpion ESCs these come with the wireless programming which is a pretty cool feature.



More detail is available on the Scorpion webpage
http://www.scorpionsystem.com/
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Old Dec 07, 2008, 06:10 PM
ramovan's Avatar
United States, NV, Pahrump
Joined Aug 2004
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The Battery

For a battery I'll need either a 10 or a 12 cell lipo depending on the motor and prop size I select. I would like this to be about 8000mah for scale flights up to 20 minutes. This is by far the most expensive component of the airplane so I really need help making a careful decision. I plan to connect two 5 or 6-cell packs in series inside the plane to get the 10 to 12-cells needed. I would like to avoiding using 4 packs to get to 8000mah but with very few manufacturers making batteries this large my choices are limited - so I'm open to that option. Keeping my packs below 6-cells each will ensure I won't need to buy a new charger.

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Old Dec 07, 2008, 06:54 PM
ramovan's Avatar
United States, NV, Pahrump
Joined Aug 2004
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The radio system

For guidance I'll be using a Spektrum DX7 transmitter and AR7000 receiver. This seems to be the best choice for me, although the AR9000 would be great (but expensive). The Stinson needs all 7 channels since I'll be using the optional flaps of course.

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Old Dec 07, 2008, 07:09 PM
ramovan's Avatar
United States, NV, Pahrump
Joined Aug 2004
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The Servos

For servos I've decided on Hyperion DS20-UMD digital servos. These metal-gear ball bearing servos provide 193oz of torque @ 6v which is just above the recommended torque range. The Stinson needs good servos and I like these in particular because they offer the precisoin of digital and the programmable options I plan to take advantage of. IE: I'll be programming slower speeds for the flaps so they have more realistic movement without the need for a servo slow device. The Stinson needs 7 servos - 2 ailerons, 2 flaps, 2 elevators, and 1 rudder. These servos should work well in all these areas, since I won't need fast servo speeds on this large scale flying airplane.

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Old Dec 07, 2008, 07:22 PM
ramovan's Avatar
United States, NV, Pahrump
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On-board Power

The Stinson is going to take a lot of power due to the higher power requirements of the digital servos and the lighting systems I plan to install. For power I decided on the Smart-Fly TurboReg. This regulator has 2 battery inputs for a redundant power source and it puts out 5.2v to 6.5v @ 17amps (with 8.4v input). I will be using two 2-cell lipos around 1000mah for the power input.


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Old Dec 07, 2008, 08:17 PM
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tommyeflight89's Avatar
Toronto, Ontario
Joined May 2004
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Wow, this should be great.
I will gladly follow along.. The biggest electric I've done is the Topflite Spitfire kit. I am pretty sure the Stinson will build much the same. My only suggestion is build light. Unlike my Spitfire, its going to be hard to come out with a very high wing loading on this bird, but lower weight will fly longer!
You should be able to swap out much of the lite ply for an electric conversion. I looked through the manual and there isn't much sheeting which is good.
I would make your own firewall-forward pieces out of A/C ply because the TopFlite stuff is more doorskin plywood. It will be much stronger..

What are you going to cover with? I think fabirc covering with pinking tape would work really well for this.
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Old Dec 07, 2008, 08:53 PM
ramovan's Avatar
United States, NV, Pahrump
Joined Aug 2004
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The weight

Good suggestion tommyeflight. The Stinson is a really stable flyer and I plan to put a really robust power system in it so I'm not too concerned about every drop of weight. I don't want to end up with a flying tank either so weight is certainly a concern.

The other electric conversions I've seen for this plane came in around 20lbs. I'll be adding a few fun extras to the plane so I think I may be a couple pounds more. The final weight will depend heavily on the covering a choose. I have not decided whether to use fabric or a monokote-like covering. The monokote would be much lighter, but the fabric would be more scale and would be totally painted making cowl/covering matching etc a non-issue. The problem is paint can add up to 3 pounds on a model this size! For this reason I'm still undecided and probably won't make a final decision for a few months when it's ready to cover. I definitely welcome any input on this.

In other Stinson electric conversions they have mentioned using lighter wood in some places of the build. So far I have the vertical and horizontal stabs, and a wing half built and have not seen any better wood selection that differs from the normal plans. It does mention some stronger (and heavier) ways of building like sheeting the entire horizontal stab, but I'm not doing this of course. There may be more weight saving oppertunities in the fuselage when I get there.
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Old Dec 07, 2008, 10:11 PM
I am UNIQUE!
Fig Jam's Avatar
Kentucky
Joined Feb 2008
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Quote:
Originally Posted by ramovan
The Stinson is going to take a lot of power due to the higher power requirements of the digital servos and the lighting systems I plan to install. For power I decided on the Smart-Fly TurboReg. This regulator has 2 battery inputs for a redundant power source and it puts out 5.2v to 6.5v @ 17amps (with 8.4v input). I will be using two 2-cell lipos around 1000mah for the power input.


Randy,

Using Lipo's and a Reg is a little old school now . Try 1 or 2 2s A123 packs without a Reg. Much cheaper and less to go wrong.

Mike
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Old Dec 07, 2008, 10:32 PM
ramovan's Avatar
United States, NV, Pahrump
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Quote:
Originally Posted by Fig Jam
Randy,
Using Lipo's and a Reg is a little old school now . Try 1 or 2 2s A123 packs without a Reg. Much cheaper and less to go wrong.
Mike
I agree, and that would likely be a weight savings; however, I already have the parts so I'll likely stick with the regulator. I like the ability to select the exact voltage output since I have several components to consider. I also likethe built-in redundancy of the TurboReg for some extra insurance. The two power inputs are isolated.
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Old Dec 07, 2008, 10:50 PM
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Fig Jam's Avatar
Kentucky
Joined Feb 2008
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Quote:
Originally Posted by ramovan
I agree, and that would likely be a weight savings; however, I already have the parts so I'll likely stick with the regulator. I like the ability to select the exact voltage output since I have several components to consider. I also likethe built-in redundancy of the TurboReg for some extra insurance. The two power inputs are isolated.
I understand Randy, it's just that by switching over to A123's you will eliminate a point of failure (the Regulator) and if you use a AR9100 you would have redundancy. Just an idea.

Mike
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Old Dec 07, 2008, 11:40 PM
ramovan's Avatar
United States, NV, Pahrump
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Quote:
Originally Posted by Fig Jam
I understand Randy, it's just that by switching over to A123's you will eliminate a point of failure (the Regulator) and if you use a AR9100 you would have redundancy. Just an idea.
Mike
A 2-cell A123 would be 6.6v which is really too high for my use. Almost everything on board wants 5v to 6v input. 6.6v would be pushing it without a regulator. I'll probably run 5.5v just to be on the safe side.

I seriously thought about the Spektrum AR9000 but I'm not sure I want to spring for it. The AR7000 is a good full-range receiver, but it does seem almost ridiculous in a plane this big.
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Old Dec 08, 2008, 05:10 AM
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staggerwing's Avatar
Binghamton Broome Cty, New York, United States
Joined Jun 2004
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A weak structure in this kit is the split landing gear legs & the way they are mounted---tie/bolt them together w/ another pc of aluminum. You can see a pic of mine in my blog
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Old Dec 08, 2008, 06:44 AM
Use the 4S Luke
feathermerchant's Avatar
USA, TX, Euless
Joined Aug 2003
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Great project. Large electrics are really coming on.

LOTS of guys flying 50cc and up are using 1 or 2 2S a123's (2300mAh) with no regulator and no problems. I am using 2 2S A123 (1100's) on a 17lb Extra300. I have 5 HS 5955 servos (330 oz in) and I fly 5 flights between charges. I put about 400mAh in each pack when I charge. The AR9100 has 2 large guage power inputs and is rated up to 10V. Not as much bling as the regulator and fan but simpler and more reliable.

Oh I do not use the switch with the 9100. I just plug in the packs.
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Old Dec 08, 2008, 04:33 PM
ramovan's Avatar
United States, NV, Pahrump
Joined Aug 2004
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Quote:
Originally Posted by staggerwing
A weak structure in this kit is the split landing gear legs & the way they are mounted---tie/bolt them together w/ another pc of aluminum. You can see a pic of mine in my blog
Very good point. Looking thru some of the other Stinson threads I can see the split landing gear is definitely a weak spot. I see others have used a one-piece aluminum landing gear from TNT. Looks like this is the way to go. The landing gear for the Stinson is $55.
http://www.tntlandinggear.com/store/..._List_Gear.htm

I'm still unsure about all the plastic parts that come with this "gold edition" kit. I really wish they would have provided fiberglass parts. I may go ahead and order the fiberglass cowl, pants, struts, etc from Fiberglass Specialties. Depends on how well the assembled plastic cowl turns out I guess.
http://www.fiberglassspecialtiesinc.com/
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