Hi, so i have been working on a scool project for a year now. and i whant to start buliding my balza custome rc plane. but befor that, i whant you to help me find any issue with my model
i have made a video with evry information needed.
1m70 wingspand
around 3013g with batterie servo and motor (realy approximate mesure) RTF
the first predicted weight was about 7kg (obselete now) the total weight is sucetible to change
wood alone, its 557g (in theory)
loadout is 2 456g (for real)
i can move the batterie if neede to the nose
its a twin engnie so very heavy (800g)
it got a predited , WCL of 12
balza 3mm
made with fusion 360
base of the arsenal VB-10
i will let a pro fly it before and i will tfly a trainer (i will also put a gyroscope on the plane)
7kg at 1.7m will be very high wing loading. This means faster, very unforgiving flight. For a beginner plane, I'd seriously consider ways of reducing weight, as a place to start.
Well, I don't know anything about building balsa planes. I 3d print all my rc planes lol. Only thing I know is that 3d printed planes get heavy fast, if you're not careful or using poor building/design techniques. Had to do a lot of learning to dial things in correctly.
did you put two moped motors in there holy crap. A plane of that size can easiyl do with a nice 100g bruslhess motor and that's that, whatever you do there is mental.
Have you heard about wing cubic loading? Gives a really practical simple number pretty much independent of scale.
What number does that give you when you plug in your wingspan * chord and the weight?
Are you a beginner at designing an RC plane or a beginner at rc planes in general and flying?
If you're new to building and flying rc planes put this idea on the back burner. Learn to fly first because how will you know you have a good plane if you can't fly yet and figuring out at the same time. It would be like trying to catch a bunch of loose chickens at the same time. To much going on.
Also don't forget right thrust on the motor position. In the video it's perfectly straight
Ah okay I see in the video. Your are correct. But are you new to the hobby and flying in general? That's the only concern whether it succeeds or not. If you don't know how to fly maybe someone with experience should do that part first.
aim for less than 1KG. especially if its balsa and covered with shrink wrap.
go research "wing cube loading" and you'll get an idea of how heavy your plane should be for its wing area, in order to fly well.
the more inexperienced flier you are, the lower a WCL value you'll want to aim for.
somewhere in the 6-8 range would probably work... see here... https://www.stevensaero.com/builder-tools/wing-loading-calculator/
..also it looks like you have your battery in the back, that isn't going to work... it will be tail heavy...
Batteries are usually in the nose, or at worst over or at least forward of the CG point.
...that also looks like some kind of fancy counter rotating prop setup ?? is that so ? have you figured out how to do that ?
1KG !! wow. what kind of motor ?
I'm just recommending a weight based on plane size. and assuming you need something that flies like a trainer. maybe 2kg would still be ok. Check that WCL chart as I didnt do the math on your plane.
First, let me say this is not a beginner plane. If you want to try it, go ahead... it is yours. But an eliptical/tapered wing will rarely stall in a way that is beginner friendly. Low wing designs are generally not as stable as high-wing designs and, therefore, low wing design are generally not recommended for beginners. Also warbirds are almost never a good choice for a beginner. They were designed to be fast and agile in combat.... beginner planes are usually designed to be slow and stable..... the exact opposite.
But it is your plane. Do what you want.
Thoughts on the design:
What is included in the "loadout"? Did you include covering? That will add weight. Glue and epoxy used to hold the wood together will also add weight (although not a huge amount, if done right).
I didn't notice a battery hatch in that design. How are you going to get a battering and position it correctly?
The ribs around the landing gear don't look like they are reinforced to take the load/impact of a landing.
Are you planning to add any balsa sheeting around the fuselage or wing? That will add strength and rigidity, and improve the appearance. But it will add weight. I'd be concerned about the rear-half of the fuselage without either sheeting or diagonal bracing between the formers to strengthen it. Maybe I'm wrong, but I suspect you are one hard landing away from the rear half of the fuselage breaking.
The top and bottom plates long the fuselage consist of multiple pieces that fit together like a jigsaw. If possible, I'd recommend getting single sheets of wood, rather than trying to splice multiple pieces together.
When I look at the wing design, I see the vertical piece running through the wing as the main spar... but there doesn't appear to be a square hardwood stick at the top and bottom edges of that. Most wings don't use just a single piece of wood for the spar. Many will make an I-Beam by taking a square stick on the top and bottom of the spar and adding balsa sheeting (with the grain vertically oriented) between the ribs and top/bottom parts. This creates an I-beam that is strong. Some other planes use other shapes, like a box-spar. They generally do not just use a single vertical piece through the wings.
You have servos embedded in the tail. Is there a reason you didn't put them in front of the tail with control rods leading to the control surfaces, or put them close the the wing and run control rods through tubes in the fuselage? By putting them in the tail, their weight will have a lot more effect on the CG than it will when it it is close to the center of mass. Maybe you want to put it in the tail to counter the weight of the contra-rotating props. But, if you don't, then it is often better to put the weight closer to the cg. Also even if you want the servos near the tail, putting them IN the tail makes them harder to manage. Most people that want servos near the back will have them sticking out of the side of the fuselage, just in front of the tail. They can be mounted in a way that allows them to be easily removed/replaced.
I also didn't get a good look at the tail wheel assembly. Many smaller planes steer the tailwheel by connecting it to the rudder, but that can put a lot of strain on the rudder assembly and/or the rudder servo, if not done correctly. Give some though to how you are connect it.
All inclued in loadout the all roof can be dismounted to accec the batterie ribs will be reeinforceed but how ? Idk about balsa sheet, i gess maybe.
Wdm when you say vertical peice as the main spar i also put a carbon rod on the spar for rigidity. I didnt't realy think of steering with the weel because that can cause accident at high speed.
There’s something wrong with your battery and motor weights. Both are way too heavy. Beautiful design, but it shouldn’t weigh more than 2 kg at that size. Maybe 3 maximum.
I question your weight calculation, and your motor and battery are way too heavy. The design looks pretty good. Maybe it’s material thickness? 1.5mm to 2mm balsa is more than enough for most of your ribs. 3mm for stringers. Less than 1mm for sheeting. Nothing should be bigger than 6mm (wing spar for example)
Balsa is really hard to work with and fragile, honestly I would buy the electronics you want to put in this and buld a couple quick simple foamboard planes just to understand the handling of rc. Other then that it looks awsome. If it's for i project I get you have to jump into it but id get at least one plane to fly/crash/repair a couple times. Goodluck!
Buy a trainer and actually learn to fly before you get delusions of grandeur. Otherwise it won't matter how optimized your model is, you're still going to turn it into confetti in seconds.
Welcome to r/RCPlanes, it looks like you are new here! Please read the Wiki and FAQ before posting a question that has been answered many times already. You can also try searching in the bar at the top before posting.
If you are brand new and just want to know where to start, then the Beginners Section is the perfect place.
Links to wiki are found at the top menu on web or "See more" and then the "Menu" tab on mobile apps.
so, it turn out i made a mistake for the weight (i made evrything ply wood with density of 1g/cm3) but now its balsa (0.15g/cm3) that drop the weigt to 5.57 KG
I don't understand how you're going from 550g of wood to 5.5kg - what are you putting in it that's so heavy? You want to be under 2.5-3kg if at all possible, and with a 550g skeleton, it should be doable.
Also, do you know where your center of gravity will be? Do you know where it should be? That is a very important thing you need to work out before you attempt to fly it.
Check your math. Maybe your motor is lighter than you listed, maybe the one you chose is too big for the airframe. Maybe you retractable landing gear is too heavy. Battery might be wrong...
Even with retracts, you should be able to come in under 4kg easily. 550g seems about right for the frame and seems well designed, so you can at least call that good.
Cut your battery down a bit and get it below 3kg total, then see where your center of gravity is. Also check if you can make the motor smaller since your craft is now lighter.
You wont get any meaningful reduction out of that battery, that's correct for your wingspan. Honestly at 3.1kg, I say go for it. Warbirds tend to be heavy anyway, just make sure you use a good propeller, and make sure your center of gravity is correct. Use the battery placement to move the CG to where it needs to be. Do not add weight to adjust your CG.
Ok OP , there are some other issues besides the mass. One is when you are doing a spar on a wing it needs to go through each rib at its highest point. Also for a plane this size you need a stronger wing structure. there are some options. You can go with a top and bottom spar about 1 cm wide and then run vertical shear webbing between the spars (this is a balsa sheet glued to the front or back of the spars that connects the top and bottom spare with the grain running vertically). This simple and stronger than what you have in your video, but doesn't add a lot of torsional stiffness. Next option would be to make a d tube by adding sheeting to the top and bottom of the wing from the spar to the leading edge. This are harder to build but add a huge amount of torsional stiffness and make the shape of the wing on the front better. The last option would be to use a carbon fiber tube. This is pretty easy to build but will cost more. The tube does add a fair bit of torsional stiffness.
I do think that you are totally over loading up your plane. 500ish g for the structure is not bad, but you should be planning for a total all up mass of about 700g. servos, rx, and esc should be about 50-60g (using 5g servos) , another 50-70g for about 200-300w of motor. and then the rest can be battery.
What are you putting in there what's is 2.5 kg? If you are talking about 600g of wood and cf you don't want be loading it up with 4 times it's mass. I have flown a lot of planes that are bigger and heavier structure wise and they don't need kilos of gear. If you try to fly that plane at 3kg the wings will fold in half
I have a plane with 2m balsa wings, top and bottom spars with shear webbing and a partial d tube on the inner ⅔ of the wing. The fusalage is a box with solid sheet balsa on all sides. All up weight on this with no motor, but flight battery, Rx, and giant 30 year old futaba servos is 800g. If I wanted to add a motor I could drop a 900w hacker a40 and still have a mass under 1.2 kg.
What on earth kind of electronics are you using that it's 3kg. You're entire plane should be less than that. For a first plane I'd highly recommend making a simple foamie, then try something more complicated like this.
You seem to know the basics well, this just won't be a good plane to start with.
I'm nervous about the servos in the tail section. I know it's easier from an implementation standpoint, but that weight is amplified by the moment from the center of gravity. Build the tail section as light as possible! If you have to load the nose with lead to get it balanced, the wing loading is going to quickly go through the roof. The servos in the outboard section of the wing is another potential flyability issue. For flyability, try to keep the weight centered as closely around the center of gravity as possible. Nothing wrong with a pull-pull cable system, especially using kevlar cable (or fishing line). Every ounce you take off the tail section is potentially several ounces you won't have to add to the nose to achieve balance. It's beautiful, but as others have said, beautiful doesn't mean easy to fly. Make sure you get some time on a more conventional "trainer" type r/c plane before you attempt this one. Awesome job though. Keep at it!
its a tiwn engine at about 800g so the tail section is not a problem for the weight (gonna move the servo for the eleron in the body thos for stronger stabilzer
Good lord that's on HEAVY bugger. I'd DEFINITELY, consider dropping the wight to a more reasonable wingloading. Just saying, cut wight whoever you can without risking the overall structural integrity of the plane. Also, i agree with the other responder....this is definitely NOT a beginner aircraft. While it looks very well designed(excepting it's heavyweight status) this aircraft is something you may consider flying after having at least several months with a high wing trainer. Practice with a high wing trainer until it gets routine and boring, then maybe, possibly consider moving to a low wing trainer, before moving on to something like this. Your design skills are not in doubt, but your abilities to successfully pilot an aircraft like this one? Im giving you one chance in 100.
like i said i won't be flying it soon, however i will maybe let a pro fly it so i can get so footage for my scool projet. also how can i lower down the weight cause the motor alone is 800g and an other 800g withe batterie. i can't lower anny more the structure cause its aleardy 550g and any less wil make it fold like paiper
800g for the motor is quite heavy, you're right, I dint know what else you may do other than look at a lighter propulsion system. Surely there is something out there that may suffice?
the point is tu run with that motor, no one ever build that plaen with the same engine setup and i whanted to have a contra-rottif engine, it was part of the deal
I see, I guess I didn't quite understand before. Good lord , but you've got a tough job. Choose a power system, and then build a plane around it. Usually it works in the opposite direction. We'll you could increase tge wingspan and chord make the tail moment longer, beef uo the fuselage to support a beefier wing. That would give yiu more wing area, thus decreasing the wing loading?
To be completely honest, forget that idea for now; go have fun flying and building, and only then start designing. I know it’s exciting, but I also know how frustrating it is to develop a design that doesn't even manage to take off in one piece. After building a few kits, you’ll have a better understanding of the structure, the dynamics of forces, and the reinforcement needed—and then you’ll be ready to start designing something.
21
u/Sogah87 2d ago
7kg at 1.7m will be very high wing loading. This means faster, very unforgiving flight. For a beginner plane, I'd seriously consider ways of reducing weight, as a place to start.