Some expert: Wingspan?

[slowjo]

Well, the thing is a mixed contraption. Carbon fibre, 3D printed parts and Foam wings and surfaces.
The thing is... I got to the airplanes from the mini quad world, and I am pretty exhausted of rebuilding planes. I spend way more time building than flying, and it's not that I don´t like building, but enough is enough.
So I tried 3D printed planes. And It's even much worse. Printing those thin walls is a pain in the ass, and boy, you better land that thing all right or those two weeks hours printing the thing... so you blame it on the brittleness of the PLA and you try PETG with equal results,
But hey!, not everything is so bad about 3D printing. You get the geometries and the angles perfect (and effortlessly) every time,
So that's it. I am using 3D printed parts to hold the CF rods and tubes that make the frame of the plane. The rest is more or less cosmetics,No glue needed. The idea is when crashing, just to break some sacrificial plastic knot, or perhaps some CF rod. A couple of hours of work.
1.1 Kg is the heaviest config, with landing gear, pilot and fairing. In the lightest config I expect it to weight around 900 g. I can´t tell you exactly because I am still waiting for the carbon fibre tubes from China

nice looking bird ; )

 

[mdcerdan]

1.4 m. No problem making the wings bigger 'cos they can be detached. but when you say a brick you mean underpowered? Also, with 1.4 m wingspan is total length 850 acceptable?
Weight is as follows

CF Tubes - 75 g (projected)
Tail 48 g
Wing 175 g (projected)
Batt 115 g
Main 480 g (includes frame, nacelle, motor, esc, video system, all wirings, RX

Minimum take off weight 893 g

Pilot 28g
LandinGearForward 35 g
Landing Gear Rear 94g
FuselageFairing - 118 g

Maximum Take off weight 1168g

When I said brick I said heavy. I made a FPV plane with a GoPro H2 for camera, DJI AVL58 VTX, 2200mAh battery and a 1.55m wingspan and it weights 1030g. You should be able to make it lighter with a 1500mAh LiPo and a far lighter camera.

850mm length is ok for 1400mm winsgpan provided you have at least 2 wing chord length from trailing edge to elevator.

 

[Piotrsko]

The traditional brick description generally invokes an aircraft with the flight and glide qualities of a thrown masonary brick.

Really heavy means minimum faster stall speed as a basic issue with resulting damage from impacts and more need to generally fly much faster which becomes another issue. The only solution there is to add wing area so that the weight is spread around more.

I like the design, kinda like a breezy or some of the early foot launched glidrs.

 

[RaavHimself]

When I said brick I said heavy. I made a FPV plane with a GoPro H2 for camera, DJI AVL58 VTX, 2200mAh battery and a 1.55m wingspan and it weights 1030g. You should be able to make it lighter with a 1500mAh LiPo and a far lighter camera.

850mm length is ok for 1400mm winsgpan provided you have at least 2 wing chord length from trailing edge to elevator.

I have 12,5% less than that. It was pretty difficult to get a decent CG with more than that. Look at the CG position that the computer shows

Yeah, I know I could do better with the weight. Instead of 4 mm CF rods, probably 2 mm rods would give me the same (if not more) strenght and stiffness as a foam sheet frame. Also, I prioritized the easiness of printing the parts rather than its weight, and in any case they are way oversized even for the PETG I am using now, and much more if I swtch to CF PETG. Also, the landing gear is just... excesive? And what about the pilot? He even has legs... But the thing is that, as a matter of fact, I am a terrible pilot, worse than bad, and have always flown better bigger slow reacting planes rather than smaller snappy ones, so I am not too worried about 1.4 m.

 

[mdcerdan]

I have 12,5% less than that. It was pretty difficult to get a decent CG with more than that. Look at the CG position that the computer shows

Yeah, I know I could do better with the weight. Instead of 4 mm CF rods, probably 2 mm rods would give me the same (if not more) strenght and stiffness as a foam sheet frame. Also, I prioritized the easiness of printing the parts rather than its weight, and in any case they are way oversized even for the PETG I am using now, and much more if I swtch to CF PETG. Also, the landing gear is just... excesive? And what about the pilot? He even has legs... But the thing is that, as a matter of fact, I am a terrible pilot, worse than bad, and have always flown better bigger slow reacting planes rather than smaller snappy ones, so I am not too worried about 1.4 m.

You can make it tail dragger, my LG made of 2.25mm music wire weights 35g with wheels, 5g more for a tail skid made of 2mm wire. That is 40g. You are the pilot so leave that 28g on the ground. Just saved 117g on this alone.
With a tail dragger configuration you can use the forward weight of the landing gear to balance the CG

 

[flyingkelpie]

Also, the landing gear is just... excesive?

Yes. Go with a simpler design. Tail dragger I'd say.

 

[TheFlyingBrit]

You need to go back to basics.
For a 1400mm wing the aspect ratio would be 5:1 so the chord would be 280mm min.
The fuselage would normally be 75% of the wing span 1050mm
Nose to leading edge is around 20%
Trailing edge of wing to horizontal stab 20% (of which the horizontal stab area would be 20% of the wing).
The Vertical stab is usually 1/3 or 33% of the horizontal stab area etc etc

Example: I fly a Volantex ascent which has an all up weight of approx 1kg with a 3s 2200 lipo, the wing dimension is 1.4 meters. So this should put you in the right ball park, it runs off a 1060kv motor and has plenty of power and could easily handle an extra 100grams.

 

[RaavHimself]

You need to go back to basics.
For a 1400mm wing the aspect ratio would be 5:1 so the chord would be 280mm min.
The fuselage would normally be 75% of the wing span 1050mm
Nose to leading edge is around 20%
Trailing edge of wing to horizontal stab 20% (of which the horizontal stab area would be 20% of the wing).
The Vertical stab is usually 1/3 or 33% of the horizontal stab area etc etc

Example: I fly a Volantex ascent which has an all up weight of approx 1kg with a 3s 2200 lipo, the wing dimension is 1.4 meters. So this should put you in the right ball park, it runs off a 1060kv motor and has plenty of power and could easily handle an extra 100grams.

My numbers are so wrong that if the thing flies I might have accidentally discovered some new aerodinamic principle

 

[RaavHimself]

You need to go back to basics.
For a 1400mm wing the aspect ratio would be 5:1 so the chord would be 280mm min.
The fuselage would normally be 75% of the wing span 1050mm
Nose to leading edge is around 20%
Trailing edge of wing to horizontal stab 20% (of which the horizontal stab area would be 20% of the wing).
The Vertical stab is usually 1/3 or 33% of the horizontal stab area etc etc

Example: I fly a Volantex ascent which has an all up weight of approx 1kg with a 3s 2200 lipo, the wing dimension is 1.4 meters. So this should put you in the right ball park, it runs off a 1060kv motor and has plenty of power and could easily handle an extra 100grams.

So putting it the other way round, once you set the wingspan you are more or less tied to a maximum weight. I suppose that for a fixed wingspan, the slower that you want to fly, the lighter that you have to be, That's logical, but I would have thought you could just stretch the wings like the ones in the gliders raising the payload and also the drag, so you just put more motor and up you go. I can see it is not so simple.
I guess I will finish and crash the plane as it is now, Next one I will use your ratios.
In your opinion, what would be an adecuate weight for a plane (the slower the better) with a wingspan of 1050 to 1100 mm?

 

[RaavHimself]

The traditional brick description generally invokes an aircraft with the flight and glide qualities of a thrown masonary brick.

Really heavy means minimum faster stall speed as a basic issue with resulting damage from impacts and more need to generally fly much faster which becomes another issue. The only solution there is to add wing area so that the weight is spread around more.

I like the design, kinda like a breezy or some of the early foot launched glidrs.

Yeah, I was thinking in otto lilienthal when I started crafting the thing

 

[RaavHimself]

Yes. Go with a simpler design. Tail dragger I'd say.

I guess that if I wanted simpler things I would not be designing planes from scratch knowing basically nothing of aerodinamics

 

[flyingkelpie]

I guess that if I wanted simpler things I would not be designing planes from scratch knowing basically nothing of aerodinamics

Just put fixed wire gear on the front 2.5mm wire and put nice big wheels on it.

 

[RaavHimself]

So this is the 3D printed brick V1.0
Wingspan 1360 mm - Weight 1250 g - Thrust 1150 g with a 4S batt
Thrust measure is static. Had a nice time sticking the scale to a column with blue tack to have a number on it

Well, awfully heavy, isn´t it? The good news is that it will lose weight very easily. Off goes the pilot and the landing gear. Tail is also unnecesarily heavy but it will be simplified (and lightened) I think I can easily shave off maybe 350 g out of that. Also, the nacelle is very heavy, and the 4mm CF Rods are way too strong. I mean, you could stand on that nacelle and it would not get damaged.

Nice things about the design. So easy to assemble. Also, very nice to do all adjustments only with a laser level and a screw driver. I like the potential of changing shapes and elements with very little effort.

So, will it fly? I haven't tried it yet because we are in a lock down due to the pandemic, and we cannot (legally) leave the city so no flying for the moment, as my town is under a rather big shadow (no fly zone) of an airport (BIO if you're wondering which one)

 

[the rc project]

View attachment 191943
So this is the 3D printed brick V1.0
Wingspan 1360 mm - Weight 1250 g - Thrust 1150 g with a 4S batt
Thrust measure is static. Had a nice time sticking the scale to a column with blue tack to have a number on it

Well, awfully heavy, isn´t it? The good news is that it will lose weight very easily. Off goes the pilot and the landing gear. Tail is also unnecesarily heavy but it will be simplified (and lightened) I think I can easily shave off maybe 350 g out of that. Also, the nacelle is very heavy, and the 4mm CF Rods are way too strong. I mean, you could stand on that nacelle and it would not get damaged.

Nice things about the design. So easy to assemble. Also, very nice to do all adjustments only with a laser level and a screw driver. I like the potential of changing shapes and elements with very little effort.

So, will it fly? I haven't tried it yet because we are in a lock down due to the pandemic, and we cannot (legally) leave the city so no flying for the moment, as my town is under a rather big shadow (no fly zone) of an airport (BIO if you're wondering which one)

It’ll fly great!

 

[Timmy]

View attachment 191943
So this is the 3D printed brick V1.0
Wingspan 1360 mm - Weight 1250 g - Thrust 1150 g with a 4S batt
Thrust measure is static. Had a nice time sticking the scale to a column with blue tack to have a number on it

Well, awfully heavy, isn´t it? The good news is that it will lose weight very easily. Off goes the pilot and the landing gear. Tail is also unnecesarily heavy but it will be simplified (and lightened) I think I can easily shave off maybe 350 g out of that. Also, the nacelle is very heavy, and the 4mm CF Rods are way too strong. I mean, you could stand on that nacelle and it would not get damaged.

Nice things about the design. So easy to assemble. Also, very nice to do all adjustments only with a laser level and a screw driver. I like the potential of changing shapes and elements with very little effort.

So, will it fly? I haven't tried it yet because we are in a lock down due to the pandemic, and we cannot (legally) leave the city so no flying for the moment, as my town is under a rather big shadow (no fly zone) of an airport (BIO if you're wondering which one)

I really like the look! Sort of like an ultralight.

 

[RaavHimself]

I really like the look! Sort of like an ultralight.

Well, that's my 3D printed flying brick V2.0. A scale model of the Quicksilver MXII, scaled down from the prop's size to a 5 inch one. I ended up with a wingspan of roughly one meter. Long story short, a lockdown and a broken umbrella with fiber glass rods. So I designed and built a model (not a flying one) to learn from it, and I ordered a bunch of carbon fiber rods and tubes of all sizes, and some CF PETG filament, and everything has just arrived so now it's a work in progress, but I think it should be pretty fast

 

[RaavHimself]

Of course it doesn´t comply with the "good" ratios provided by @IanT, but neither does the real plane, so I've just scaled it lacking better knowledge (I must admit that I forgot everything I ever studied about the Reynolds number and all that stuff) ,

 

[Quinnyperks]

1.4 m. No problem making the wings bigger 'cos they can be detached. but when you say a brick you mean underpowered? Also, with 1.4 m wingspan is total length 850 acceptable?
Weight is as follows

CF Tubes - 75 g (projected)
Tail 48 g
Wing 175 g (projected)
Batt 115 g
Main 480 g (includes frame, nacelle, motor, esc, video system, all wirings, RX

Minimum take off weight 893 g

Pilot 28g
LandinGearForward 35 g
Landing Gear Rear 94g
FuselageFairing - 118 g

Maximum Take off weight 1168g

What size battery?

 

[RaavHimself]

What size battery?

1500mAh 4S or 1800 mAh 3S

 

[Quinnyperks]

1500mAh 4S or 1800 mAh 3S

Ah ok.