bogusbandit56
In some country`s a sub 250 gram or 8.6 ounces plane is in the toy category and does not fall under government ruling for drones, but could such a light aircraft be a viable flyer?

I have set myself the challenge of building a sub 250 gram plane that can hold it`s own against the heavier type of parkjet with a wing span of 787 mm or 31 inches.
I have opted for a flying wing for the obvious reasons of no weight of fuselage and empenage and lower drag compared to the ridiculous amount produced by a modern jets like the F15, Mig 29 or Sukhoi Su27 designs.

I will be using a diminutive emax MT1806 2280kv motor that on a very good day produces 460 grams of thrust.
A very old and tired 1000mha zippy compact battery and a no name 15 amp esc.

I have weighed the electrical components and push rods and collectively they weigh 76 grams including a 6x4 prop.
The battery weighs 76 grams.
The airframe which is not finished yet, so we need to add a few more grams is currently 60 grams.

The air frame will be around the same shape and size of my old Gotha P.60 based design, which I know is a very stable aircraft.
Wot, no Depron?
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Wildthing
In some country`s a sub 250 gram or 8.6 ounces plane is in the toy category and does not fall under government ruling for drones, but could such a light aircraft be a viable flyer?

I have set myself the challenge of building a sub 250 gram plane that can hold it`s own against the heavier type of parkjet with a wing span of 787 mm or 31 inches.
I have opted for a flying wing for the obvious reasons of no weight of fuselage and empenage and lower drag compared to the ridiculous amount produced by a modern jets like the F15, Mig 29 or Sukhoi Su27 designs.

I will be using a diminutive emax MT1806 2280kv motor that on a very good day produces 460 grams of thrust.
A very old and tired 1000mha zippy compact battery and a no name 15 amp esc.

I have weighed the electrical components and push rods and collectively they weigh 76 grams including a 6x4 prop.
The battery weighs 76 grams.
The airframe which is not finished yet, so we need to add a few more grams is currently 60 grams.

The air frame will be around the same shape and size of my old Gotha P.60 based design, which I know is a very stable aircraft.


Boy that will be a lightweight, what kind of ws do you think you will end up with? 
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mastermalpass086
I presume, when it comes to making ultra-light planes that are as big as the standard parkjet your options do get a bit tight. I'm imagining profile planes with small batteries.

I am wondering about simply building tiny planes - they won't stand a chance in wind, but they won't need a lot of space. My Hubsan H107C quad uses these minuscule brushed motors that are less than a CM in diameter, and you could power them for a good ten mins on a 650MaH 1S. Years ago I had this clumsy little bipe called an X-Twin. It had hardly any control, pitch was controlled with speed, yaw was differential thrust and roll was held by dihedral. The big wad of a nose made it crash-proof, but my point is that it was the floatiest thing and could cruise around at under 10mph - I would fly it around that graveyard in front of my house, which is otherwise rotor-wing territory.

[41ymYUa2zRL] 

I imagine if you scaled down your Horten Ho-7 to a 20" wingspan you'd have a garden flyer like the X-twin but with a lot more control and grace.
BRB - Building another nosecone.
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bogusbandit56
Wildthing wrote:


Boy that will be a lightweight, what kind of ws do you think you will end up with? 


The same as my Gotha P.60 31 inches.
Wot, no Depron?
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bogusbandit56
I presume, when it comes to making ultra-light planes that are as big as the standard parkjet your options do get a bit tight. I'm imagining profile planes with small batteries.

I am wondering about simply building tiny planes - they won't stand a chance in wind, but they won't need a lot of space. My Hubsan H107C quad uses these minuscule brushed motors that are less than a CM in diameter, and you could power them for a good ten mins on a 650MaH 1S. Years ago I had this clumsy little bipe called an X-Twin. It had hardly any control, pitch was controlled with speed, yaw was differential thrust and roll was held by dihedral. The big wad of a nose made it crash-proof, but my point is that it was the floatiest thing and could cruise around at under 10mph - I would fly it around that graveyard in front of my house, which is otherwise rotor-wing territory.

I`ve had one of those type of Bipes and they are useless in all but dead calm weather and the handling is sketchy.
Although they are very light they also produce a lot of drag and drag is the real killer with aeroplanes.
The challenge is to build a large lightweight plane around the size of a park jet that can fly in a bit of a breeze and have full control. 
I doubt that my project will be strong enough to perform rolls and loops as I am using some XPS underlay purchased from B&Q, but I will try to do them and see the out come. It is a pale green and nowhere near as strong as depron, I do like the colour though🙂
The KSP Skyblade was around 300 grams so I can save a lot of weight with the little quad motor which is 13 grams lighter than the bell motor and using KFm2 instead of KF4 the foam is also lighter than the depron I used on the Skyblade. The real killer will be the lack of carbon reinforcing, that is in strength not lightness.
 If this one fails I will try an Armin wing that will not require carbon as the stressed wing will provide enough strength.


[41ymYUa2zRL] 

I imagine if you scaled down your Horten Ho-7 to a 20" wingspan you'd have a garden flyer like the X-twin but with a lot more control and grace.
Wot, no Depron?
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DualDesertEagle
Believe it or not, my failed Dominator build was still slightly lighter than 250 despite having a full-blown fuselage and a heat-shrunk PET canopy, being glued together with a bunch of hot glue and lots of excess servo wire I didn't want to cut off and resolder.
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bogusbandit56
Believe it or not, my failed Dominator build was still slightly lighter than 250 despite having a full-blown fuselage and a heat-shrunk PET canopy, being glued together with a bunch of hot glue and lots of excess servo wire I didn't want to cut off and resolder.


Hot glue and extra wires are the killer of light building and I think you did very well to hit that weight.
As I recall the Dominator was not very good in the wind and lacked direction.
I have just finished gluing up the Lite P.60 and all up weight is 245 grams so it does`nt need to be registered.
The proof of the pudding will be in the eating as we say in the UK.
I`m sure I can fly this aircraft but how durable it will be is questionable.

A couple of things I don`t like on my build is that in order to keep the weight down I have mid mounted the motor so it has an in efficient prop in slot. I have added little fins either side of the slot in order to give it some rigidity.
The other questionable design choice is the wide fuselage. I wanted to make it simple and strong and keep the weight centered around the CoG which is the strongest part of the plane.
In order to place the battery, ESC and receiver close to this spot the fuselage had to be wider than I really would have liked.
Wot, no Depron?
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Wildthing


Hot glue and extra wires are the killer of light building and I think you did very well to hit that weight.
As I recall the Dominator was not very good in the wind and lacked direction.
I have just finished gluing up the Lite P.60 and all up weight is 245 grams so it does`nt need to be registered.
The proof of the pudding will be in the eating as we say in the UK.
I`m sure I can fly this aircraft but how durable it will be is questionable.

A couple of things I don`t like on my build is that in order to keep the weight down I have mid mounted the motor so it has an in efficient prop in slot. I have added little fins either side of the slot in order to give it some rigidity.
The other questionable design choice is the wide fuselage. I wanted to make it simple and strong and keep the weight centered around the CoG which is the strongest part of the plane.
In order to place the battery, ESC and receiver close to this spot the fuselage had to be wider than I really would have liked.


That looks great, what ws did you end up at? 

I love my Gotha with the midmount. 🙂 It even has a elevator just behind the prop beside having the elevons and it is super agile.  
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bogusbandit56
Thanks Jeff, I arrived at the wing span it started out with, which I have already stated 3 times in this thread is 31 inches or 787 millimeters the same as the original P.60. If you put your glasses on and look at the above picture you can see the old P.60 and the lite P.60 are very much the same size.😜
I know you were very happy with your version of the P.60 but there is no doubt that prop in slot robs power, but it also has it`s advantages for super maneuverability and centering the weight.
As the build is only 5 grams off the target weight there is not much room for another 5 gram servo and push rod and horns.
We have some beautiful weather today but I am going to let the Uhu Por cure for 18 hours so bits don`t fall off.😏
Wot, no Depron?
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Wildthing
I gather no cf rods or epoxy glue .  Hard to tell being solid white do you have kf4's on it? 
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bogusbandit56
Wildthing wrote:
I gather no cf rods or epoxy glue .  Hard to tell being solid white do you have kf4's on it? 


Just two carbon tubes running span wise with KFm2. Only used Uhu Por glue, but that is what I used for spars and carbon normally.
I recon it will flap a bit so I will need to take it easy in the turns.
I will post some more photo`s tomorrow and if the weather is nice, some flight footage.🙂
I have a better idea for the wing using a tapered balsa spar with a 3mm depron KF step, laziness only prevented me from building it that way😜
Wot, no Depron?
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quorneng
A 'proper' outdoor plane at sub 250 g?
NewFuseFin.jpg
With a span of 40" (1020 mm). a Blue Wonder 1500kv driving a 7x4 prop from an 850 mA 3s it is fully aerobatic, has true unlimited vertical yet can power on for close to 1 hour.
It weighs just 221 g.
More conventional - a Super Cub
02May17n.jpg   
Same 40" span, with a 1000 mAh 2s it weighs 240 g. 
Or even a scale EDF
13Aug17.jpg 
32" span (610 mm), 40 mm EDF, 1400 mAh 2s. Hand launch and belly land flights of nearly 10 minutes are possible.
It weighs 202 g.
The secrete? Thin (2 mm) Depron sheet and knowing how to make the best structural use of it. ðŸ˜‰    
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bogusbandit56
quorneng wrote:
A 'proper' outdoor plane at sub 250 g?
NewFuseFin.jpg
With a span of 40" (1020 mm). a Blue Wonder 1500kv driving a 7x4 prop from an 850 mA 3s it is fully aerobatic, has true unlimited vertical yet can power on for close to 1 hour.
It weighs just 221 g.
More conventional - a Super Cub
02May17n.jpg   
Same 40" span, with a 1000 mAh 2s it weighs 240 g. 
Or even a scale EDF
13Aug17.jpg 
32" span (610 mm), 40 mm EDF, 1400 mAh 2s. Hand launch and belly land flights of nearly 10 minutes are possible.
It weighs 202 g.
The secrete? Thin (2 mm) Depron sheet and knowing how to make the best structural use of it. ÃƒÂ°Ã…¸Ëœâ€°    

Excellent builds Q. I knew you built light but I didn`t realize these models were sub 250 grams.
Are those the all up weight with batteries?
I don`t have the patience or building skill you have and now 2mm depron is no longer available I would have to slice my own from blue foam slabs with a hot wire.
Thanks for posting🙂
Wot, no Depron?
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Wildthing
I use more then 250g in glue let alone a full build with hardware. ðŸ˜‚😂😂😂😂
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quorneng
bigusbandit56
Yes those weights are "ready to fly". I checked the weight of each including its battery as I was writing the post.
I wouldn't claim they are 'beginner' crash proof but being so light they fly relatively slowly and can survive an untidy 'arrival'.
The biggest drawback if they are 'fair weather only' flyers.     
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