I need help. Building a RC plane

[kennycan]

I am building a 80cm wingspan one propeller foam board airplane.It is almost like the Flitetest simple scorch without the wheels and a few small modifications.


when i took it out to test, I pitch the elevator to 45degrees up and hand launched the rc plane at full throttle.

First test the plane went around 2m and pitch up around 5 degrees before crashing head first.

Second test the plane went around 2m and crash head first again. But after that the esc no longer worked.


The specs is
30A Esc
2200kv motor
2200mah 3s 25-50c lipo battery
plane weight is approx 1kg
propeller is a 6035
More specs in the picture


I am new to the hobby and would appreciate any help to prevent my plane from crashing without even flying. Thank you

 

[Ryan O.]

Hello, do you know the motor stator size specifications or have a link to the motor you’re using? If not a picture should do. Also, where on the wing does the plane balance. It should balance approximately 1/4-1/3 back from the leading edge of the wing. Other pictures of the plane and linkages would be helpful in troubleshooting too.

 

[luvmy40]

Sounds like you are tail heavy.

 

[kennycan]

Hello, do you know the motor stator size specifications or have a link to the motor you’re using? If not a picture should do. Also, where on the wing does the plane balance. It should balance approximately 1/4-1/3 back from the leading edge of the wing. Other pictures of the plane and linkages would be helpful in troubleshooting too.

I have just uploaded the pictures. thank you for your help

 

[kennycan]

Sounds like you are tail heavy.

Thank you for helping me. When I measure the centre of gravity, it is a little tail heavy when measuring from 1/3 of the wing. I am scared that if i make it nose heavy it will be too heavy as i have to add extra weight

 

[kennycan]

Does anyone also know how to firmly attach the motor? everytime I crash the paper from the foam board comes apart with the motor. I attach it with four screws and hot glue but it still came off

 

[Merv]

Does anyone also know how to firmly attach the motor? everytime I crash the paper from the foam board comes apart with the motor. I attach it with four screws and hot glue but it still came off

Use a piece of thin wood, 3-5 mm, glue the wood to the foam, then tape, from one side across the wood to the other side. Use fiber reinforced tape if you can, run the tape 5-7 cm back on each side. Screw the motor to the wood.

You are very tail heavy. Move things around until the plane will balance at 25% of the wing cord from the leading edge.

Make sure the numbers on the prop are facing the direction of travel. If not you will only get about 40% of the expected thrust.

45 degrees is far too much elevator, maybe 10 degrees at most. If you can have someone else throw the plane. You want a good stiff throw, like throwing a ball 15 meters, throw the plane slightly upwards, 20-30 degrees.

 

[kennycan]

Use a piece of thin wood, 3-5 mm, glue the wood to the foam, then tape, from one side across the wood to the other side. Use fiber reinforced tape if you can, run the tape 5-7 cm back on each side. Screw the motor to the wood.

You are very tail heavy. Move things around until the plane will balance at 25% of the wing cord from the leading edge.

Make sure the numbers on the prop are facing the direction of travel. If not you will only get about 40% of the expected thrust.

I shifted the battery to the front and shifted the wings slightly behind. If i add weights in front, would the rc plane be too heavy? Also, why do you know why the plane crashes nose first if it is tail heavy?

 

[quorneng]

First your plane design is what is called 'close coupled'. The tail plane and the elevator are rather close to the wing which will make the plane very sensitive to any elevator or rudder input. I note you said you pitched the elevator up to 45 degrees. It will not fly like that!

In theory if you have the balance point at the right place the plane should glide (take the prop off) making a gradual descent in a constant attitude. When you can do repeated glides then and only then you can try adding a little power. It is likely with a low power setting it will just glide a bit further but you should be able to detect if the plane tends to bank left or right by itself and whether the power is causing the plane to climb, stall and dive into the ground. You can likely correct these tendencies by adjust the trim buttons on the transmitter.

What this does show is that flying an "own design" without quite a bit of flight experience is very likely to end in failure.
Now if you could get an experienced pilot to test your plane and set it up to fly properly then if you have difficulties its down to you.
This is why the normal recommendation is to buy an RTF (Ready To Fly) plane or copy a proven design exactly then provided you set it up according to the instructions it will fly. The only question then will be whether you have the skill to control it.

Most of us of a certain age went through this sort of process, crashing a lot but learning as we went along.

To answer your last question at 1 kg it is heavy enough as it is. Have you thought of moving the elevator & rudder servo and the radio as far forward as possible. Any 'dead' weight at the tail needs up to 5 times the weight in the nose to counter it.
A properly balanced plane will fly, A properly balanced but lighter plane will fly much better.

 

[Merv]

I shifted the battery to the front and shifted the wings slightly behind. If i add weights in front, would the rc plane be too heavy?

Don't know. Depends on how much weight you add. Adding weight is the last resort.

A different motor might help, same size but 1000-1200 kv, then you could use a larger prop, 9-10 inch. The 2200 kv 6 inch prop is a higher speed setup.

Think transmission, higher kv & smaller prop is like high gear, goes fast but no lugging power. Lower kv & larger prop is like low gear, lots of lugging power but limited top speed.

 

[Ryan O.]

I am building a 80cm wingspan one propeller foam board airplane.It is almost like the Flitetest simple scorch without the wheels and a few small modifications.


when i took it out to test, I pitch the elevator to 45degrees up and hand launched the rc plane at full throttle.

First test the plane went around 2m and pitch up around 5 degrees before crashing head first.

Second test the plane went around 2m and crash head first again. But after that the esc no longer worked.


The specs is
30A Esc
2200kv motor
2200mah 3s 25-50c lipo battery
plane weight is approx 1kg
propeller is a 6035
More specs in the picture


I am new to the hobby and would appreciate any help to prevent my plane from crashing without even flying. Thank you

I would agree with Quoreng, when first flying it’s usually worth building an already proven aircraft from plans or a kit to reduce the number of variables. A less short coupled plane will definitely be easier to fly. Your motor is usually used on parkjets, but it should work on small B pack aircraft and large mighty minis with some jerry rigging. I’d recommend the Simple Scout or Tiny Trainer for that motor.
Here is the link for the simple scout plans (the trailing edge semicircular pattern can be cut straight to save a lot of hassle): http://s3.amazonaws.com/plans.flitetest.com/FT_Simple_Scout_v1.0_Tiled_A-Size.pdf
Here’s the tiny trainer: https://s3.amazonaws.com/plans.flitetest.com/stonekap/FT-mini Tinytrainer-TILED-PLANS.pdf
Here’s a video on how to print and cut out the plans:

 

[Merv]

...Also, why do you know why the plane crashes nose first if it is tail heavy?

Your previous post stated "it is a little tail heavy when measuring from 1/3 of the wing".
Translation, you are a lot tail heavy.

Experiance tells me be very careful when you move the CG beyond 30%. That's about the point any plane becomes uncontrollable, a flying squirrel. Your plane will fly much better when it balances at 25%.

 

[kennycan]

Thank you for all your help. I will build a flite test kit and learn the beginner things first.

 

[danskis]

Also - if your elevator can go up at 45 degrees that is way to much - it will be uncontrollable if you do get it flying. It should go up and down no more than 10-13 degrees when the plane is balanced properly/

 

[FoamyDM]

Thank you for all your help. I will build a flite test kit and learn the beginner things first.

Good luck. There are also some great podcasts to help digest and learn what you need to know.
Aviation RC Noob Podcast
The RC Plane Lab
The Flite Test Community Podcast