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Jan 19, 2019, 04:45 AM
Registered User
Thread OP
Help!

I think I've made my wing wrong, anyone know where to go from from here?


Ok so I was told to ask here about my scratchbuild

Essentially, I followed experimental airlines armin wing tutorial for my first scratchbuild/plane, with the plan of building my first plane and remote from scratch. The electronics are all done except for gps, but I have a few questions about my wing I made.

After following the tutorial for his 7 inch chord wing, I have made a wing with dimensions of 40 inch wide and I think 10 inch chord (7 and a bit inch for the aerofoil bit and 2.5 inch aileron). From what I can work out, I'm pretty sure this is not a good ratio. The second problem being that the foamboard available here is art grade, $10 a piece, papers a to get off and even then is impossible to bend in a nice curve. So Ive ended up with a massive wing with a leading edge that nearly looks like 3 separate flat sheets joined together.

The main electronic parts im using are:
https://hobbyking.com/en_us/hobby-ki...c-4a-sbec.html
https://hobbyking.com/en_us/turnigy-...lipo-pack.html
https://hobbyking.com/en_us/turnigy-...or-1450kv.html

So the questions are as follows, mainly is this wing usable as it is with these components? I'm pretty sure I've got the guts for building a faster speed plane, yet I think I made a slow flying wing. Will the combo work? Also, the wing is all I've made so far, so any tips/recommendations on a fuselage/tail to go along with all this? I would prefer to what I've already got if possible, but I can get whatever needed if its required.

cheers and thanks in advance,
Bailey
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Jan 19, 2019, 07:40 AM
Sokol
JureZ's Avatar
the links that you posted are broken,as you simply pasted the links in your message, you need to use the link icon tool (globe with chain link) to insert a link.

the fact that the chord is larger than what you intended, will make it a "slower" wing , it will perform differently than the original was expected to, but will not be a total failure.

your first scratch built plane will be a success if it flies at all, it does not need to be at the edge of competition class designs , and be the ultimate performer.

A very important set of parameters to take into account are the wing loading and the cubic wing loading.

These will define to a large extent how will your model fly.
The wing area that you report is 400sq in , or 2.78 sq ft

so, how heavy is the model, ready to fly ?
if it is lighter than 22 oz or 620 g , you will have no problem. I would limit the weight to 32 oz or 900g maximum .
( the heavier it is, the faster it will need to fly to stay airborne, flying is analogous to to water skying , but in another fluid ...)

You will need also about 100 W to 140 W of electrical power into the motor to fly comfortably.

for more references see:
https://www.rcgroups.com/forums/show...r#post17179115
Last edited by JureZ; Jan 19, 2019 at 08:00 AM.
Jan 19, 2019, 09:08 AM
An itch?. Scratch build.
eflightray's Avatar

"I think I've made my wing wrong, anyone know where to go from from here?"


If you are thinking of building another wing, look in the 'Sticky' threads at the top of this forum, there is one starting - Kline-Fogleman (KFm) Airfoils ... .

Post #2 shows the various types that are fairly easy to make using flat sheet foam.

.
Jan 19, 2019, 09:13 AM
treefinder
springer's Avatar
A couple more points: the flats you mention on the wing aren't likely to be a problem functionally, although they may not be as pretty as you'd like. The jedelsky wing is essentially a series of flats forming a sort of airfoil. Works fine at our scale.

A picture or two will go a long way to helping us understand the issues. Try a plan view - best straight on top view you can get. A front and rear view and a 3/4 view. Then we can see what you have and look for possible problems.

As jurez said, in all likelyhood you have reduced wing loading with the increased chord, which will make a floatier flyer as long as you don't add too much weight. That is generally good for a first build!
Jan 19, 2019, 03:05 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Will you be using this plane to teach yourself to fly an RC airplane ( without the assistance of an experienced RC airplane flyer ) ?
If so , I recommend building a simple beginner plane suitable for an unassisted first timer . There are many suitable simple designs here in this forum , let me know if you would like some recommendations . If it is difficult to bend your foam board , all of the simple designs do not involve bending the foam into a curved airfoil .
Jan 19, 2019, 05:52 PM
Registered User
Thread OP
Alright thanks so much for the replies! Now to follow up.

Quote:
Originally Posted by JureZ
the links that you posted are broken,as you simply pasted the links in your message, you need to use the link icon tool (globe with chain link) to insert a link.
Sorry about that! Here are the actual links:
https://hobbyking.com/en_us/hobby-ki...c-4a-sbec.html
https://hobbyking.com/en_us/turnigy-...lipo-pack.html
https://hobbyking.com/en_us/turnigy-...or-1450kv.html

As for your question on weight, I honestly have no clue.
Wing ~ 300g
Servo x 4 ~ 200g (https://hobbyking.com/en_us/hobbykin...20sec-51g.html)
Motor system ~ 200g
ESC ~ 60g
Battery ~ 250g
Rest of the electronics ~ 50-100g
Piece of foamboard to make rest of plane ~ 400g

so in all I guess its looking to be around 1500g which I guess isnt ideal.
But the motor I got is rated for 1600W, which is a fair bit more than what you said. So yeah I hope thats some usable information for ya

eflightray ---
Quote:
If you are thinking of building another wing, look in the 'Sticky' threads at the top of this forum, there is one starting - Kline-Fogleman (KFm) Airfoils ... .
Yeah that looks like a much simpler wing for what Im doing. Will try if this one doesnt work

Springer----
Quote:
A picture or two will go a long way to helping us understand the issues.
Sure ill attach some pictures
Idk why you need front or back views of a wing, I assume you would mean the plane, but like I said I haven't made it yet.
I guess the flats arent too bad, if theres wings made from flats already this should be pretty fine then.

balsa of carbon-----
Quote:
Will you be using this plane to teach yourself to fly an RC airplane
Yes I will be unassisted. Idk of anyone that even does this sort of stuff in the area. There probably is but yeah ill be solo.
Quote:
I recommend building a simple beginner plane
I would definitely appreciate some recommendations! Just as long as it can use all the parts I currently have available that has been listed cos I dont really feel like waiting another few weeks for more parts lol

So yeah, the wing design might be ok, but I might be overweight for a floaty plane.

Bailey
Jan 19, 2019, 06:14 PM
Sokol
JureZ's Avatar
OK your stuff is really meant for a plane with twice the wing area.
As is set up now , it is definitely not a trainer ( Wing Loading of 18 oz/sq ft, 3+ lbs AUW )



Follow BoC standard good advice , and build a simple , proven trainer design such as the EzFly , ( he is the master in this topic ) :


https://www.rcgroups.com/forums/show...-trainer-plane


http://fancyfoam-com.3dcartstores.co...Kit_p_105.html
Jan 19, 2019, 06:41 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by Bails_64
balsa of carbon-----

Yes I will be unassisted. Idk of anyone that even does this sort of stuff in the area. There probably is but yeah ill be solo.

I would definitely appreciate some recommendations! Just as long as it can use all the parts I currently have available that has been listed cos I dont really feel like waiting another few weeks for more parts lol


Bailey
OK , if you are an unassisted first time RC airplane flyer , I recommend the following :

Some people catch on quickly when they fly an RC airplane for the first time ..... you could say they're a natural .
But most people need to start with a plane that can fly slowly and is stable ( self-righting ) .
And for an unassisted first time flyer it's probably best to build a disposable airframe , since it's likely to crash a time or two .

The main ingredient for slow flight is "low wing loading" ...... maximum wing area combined with minimum weight . With your heavy electronics , you can achieve low wing loading by building a large airplane with a lot of wing area .

The main ingredient for stability is an airframe designed to have a high wing with dihedral ( wing ends angled up ) , or stability can be achieved with electronic stabilization .


A very simple disposable airframe that will probably work with your electronics is the Super Easy , it's ugly ( looks like a big paper airplane ) ..... but it flies well . It also protects your motor/prop if crashed nose-first .



Here is a video of a first time builder/flyer attempting his first flights with a Super Easy :


RcGroups Scratchbuild "SuperEasy" maiden flight (1 min 28 sec)






Here is a video of a later flight by the same guy and his Super Easy :


RcGroups "SuperEasy" scratch build short flight (1 min 10 sec)
Jan 19, 2019, 07:41 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
If you haven't already done so , practice on an RC simulator . There are free RC sim downloads for PC , and there are free RC sim apps for touchscreen mobile devices .
Jan 19, 2019, 10:17 PM
Registered User
Thread OP
So from what I can work out from the replies, the wing wont work.
I know that BoC's dart plane thing would be easy but tbh I'm not too keen on it.

The other thing both of you said was to actually increase the wing size, so I thought maybe it would be possible to add dihedral ends on both sides of the wing, say 10 inch on each side. Would this help my wing loading enough to fly with this weight?
I also saw about just using a foam rectangular tube for the frame, this would be easy to make/throwaway and easy to attach to the wing as well as give ample room to place electronics to stabilize, and possibly cut a hole in it to place the motor inward a bit and away from the nose.

From doing some searching for trainer planes, all the ones I could find used really lightweight stuff, which I dont have, so I dont really know if I could make any of them work.

Another option is if I made a second, similar 300g wing and put them together, it would give me 800 sqinch and around a weight of 63 oz, giving around 11.5 oz/sq foot. If i did this it might be way oversize though, but would fit your trainer category im pretty sure.

In all I'm not really looking to build a trainer specifically, just something that'll work. I know this will come down to my ability but if I do crash, I can just repair and rebuild. I never really checked previously, but now that I put it in some calculators, 1500g with a 400sq inch wing seems to break em all, and idk the more I think about it the more I think adding dihedral ends to my wing might work. Like say an extra 10 inch of some sort of simple wing type at a 10-15 degree angle on the ends? idk

Bailey
Jan 19, 2019, 10:30 PM
treefinder
springer's Avatar
While you can try various methods to get wing loading down by increasing the size, you might look at the foamcore itself. From your pictures, the paper is awfully shiny, it looks like it may have a plastic film on the paper. That will make a really heavy build no matter what plane you pick. Have you tried picking a corner, and rolling the paper around a dowel, or broomstick, etc? While it may look nice and add dent resistance, I think you will do better with it off. That will enable you to get the weight down to something reasonable. Some of the art foam core has an adhesive layer between surface skin/paper and foam. If you can get to the interface between the adhesive and foam it should be easier to remove by rolling. Other wise, you may want to check out your local equivalent of dollar stores, or craft stores, that typically have some really cheap foam core for posters, etc. I understand that Bunnings has some foam that guys use for planes. That is unless like some other guys in OZ who live hundreds of kilometers from civilization!
Jan 19, 2019, 11:52 PM
Build, crash...repeat
AleRRon's Avatar
Bailey, I admire your sense of adventure and determination. If you want to build a plane using an Armin wing then the guy who shows how to make it also shows how to build a tubular fuselage and tail assembly at the Experimental Airlines’ Foamboard Scratchbult University Sticky thread in this forum. I have not built his planes but I’m sure they work.
You built a wing that should fly, but if it’s heavy, you’ll need a lot of power and speed. I suspect the Foamboard you used is very heavyweight and as you said it’s hard to bend. Experimental Airlines lists foam boards that would work in various parts of the world and mentions some brand available in Australia. Check his Sticky thread for it. You need pretty light stuff so you might want to source that and start over.
Also, is your motor really 200g? Most motors used in foamies are 27-65 g so either your estimate is way off or it’s a massive motor.
Also are you really using 51 g servos? Again, we are using 5-9 g servos usually.

Here’s the Foamboard you need: Australia - from Riot Art, foamboards.au
Jan 20, 2019, 12:26 AM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by Bails_64
I know that BoC's dart plane thing would be easy but tbh I'm not too keen on it.

From doing some searching for trainer planes, all the ones I could find used really lightweight stuff, which I dont have, so I dont really know if I could make any of them work.

In all I'm not really looking to build a trainer specifically, just something that'll work. I know this will come down to my ability but if I do crash, I can just repair and rebuild.
Bailey
If your goal is to learn to fly an RC airplane : doesn't it make sense to have your first ( likely to crash ) plane be a simple , disposable airframe that's a quick , easy build ....... and a quick , easy rebuild ? Once you have learned to fly and are not crashing anymore , then build & fly a more beautiful plane .

You can build a slow flying plane with your heavy electronics , you just have to make the airframe with a lot of wing area . "Wing loading" is the weight of the plane relative to the wing area .

Another good trainer you can make is the EzFly . It requires downloading & printing plans , then transferring the plans to the foam board . If you make an EzFly scaled up to 150% , it will have enough wing area to give you the low wing loading needed for slow flight . I have made a 150% EzFly that uses a 2200mAh 3S battery ( similar to the battery you have ) , here is a video of it flying :



( slightly ) better video of 60" wingspan EzFly (2 min 32 sec)




This EzFly ↑ has a 150% fuselage & wing chord , but the wingspan is 200% .
Last edited by balsa or carbon; Jan 20, 2019 at 12:36 AM.
Jan 20, 2019, 01:55 AM
Registered User
Thread OP
springer-----
Ive found it to be utterly useless trying to get the paper off this foamboard without chemicals. With just your fingers, it doesn't budge at all and either takes a chunk out of the board or just rips the paper in half with the bottom still stuck on the adhesive. Water doesn't do anything, soaked a piece for an hour and it did no better than with your fingers, except you rub off the top layer instead of ripping it. I spent 2 hours painting methylated spirits all over the surface giving it all a good soak and it seemed to dissolve the adhesive underneath eventually (this was only for about a third of a side). So yeah, the paper is pretty much impossible to get off without spending all day getting all the paper off, but might be worth it possibly.
The plastic film is packing tape, as per the videos instruction. At the time of construction I assumed it was for aerodynamic purposes, but the bloke never said what it was for. I even tried looking up online but I must've been using the wrong keywords to get the answer I was wanting. I only found out a week or so ago that it was mainly for crash resistance, and only added weight pretty much.
As for types of foamboard, this art stuff was all that I could get locally at this size (40 inch). Our local Bunnings when I went in straight up didn't stock it, in fact the guy that asked if I needed anything straight up didn't know what it was. The only other foamboard I could find was in a dollar shop BUT it was only in something that looked like A4 size.

AleRRon-----
Yeah I think I'm gonna order some more proper board from somewhere and try again. The place experimental airlines suggested charges something like $16 a sheet PLUS postage, so I'm gonna have a look around first.
The motor itself isn't 200g, its 180g according to HK. The total motor system (motor, connectors, propeller, prop hub, fastening bolts and nuts weigh 220g in total. So yeah it isn't a small motor. I bought it because I thought it was the best in terms of performance for its price, and that I would limit its power through my DIY remote until I eventually made an actual stunt plane or something. Back when I bought it all I wasn't really thinking about weight, mainly because I had absolutely no experience and didn't really know what weight it was going to end up being/what was a good limit.
As for the servos, they were cheap and I could use them for other things then the plane. Tbh I just thought those small ones would'nt've had enough power to push against the air effectively at speed. Idk at the time once again I didn't really know what I was in for and I sort of thought the small ones might've locked up in a dive or something. But even with the 9g servos, taking all the paper/tape off the foamboard and used an actual receiver I'm pretty sure the weight will be around 1kg

BoC----
That plane looks pretty good actually. I realized that its the same one that JureZ suggested, I just clicked the wrong links in the thread and thought it was a completely different thing lol. I might build that one first before I try anything else I guess.
Would you recommend the 150% scale with or without the 200% wingspan? I'm assuming with and if so are there printouts for that or do I have to make them.
Sorry for being a bit stubborn about that, idk I was pretty keen on building it all without plans but I guess I should start small at first.
Jan 20, 2019, 03:05 AM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by Bails_64


BoC----
That plane looks pretty good actually. I realized that its the same one that JureZ suggested, I just clicked the wrong links in the thread and thought it was a completely different thing lol. I might build that one first before I try anything else I guess.
Would you recommend the 150% scale with or without the 200% wingspan? I'm assuming with and if so are there printouts for that or do I have to make them.
Sorry for being a bit stubborn about that, idk I was pretty keen on building it all without plans but I guess I should start small at first.
To achieve the lowest possible wing loading ( for slow flight ) , make the wingspan 200% . I increase the wingspan on an EzFly by adding to each wing-half at the root ( see drawing below ) .

To get plans for a 150% EzFly , open the PDF file on Adobe Reader ..... then at the top of the page increase the size to 150% . On your printer's set up page , select "poster" , "cut marks" & "labels" ..... the printer will then print out tiles that can be assembled into a large poster-sized set of plans for a 150% EzFly .

Here is the PDF file for the EzFly plans : https://www.rcgroups.com/forums/show...6&d=1334660760
Last edited by balsa or carbon; Jan 20, 2019 at 03:14 AM.


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