Here's my first RC design

[Chrono]

Hello!!!

I don't know if this is exatcly the forum to post this, but i wanted to share a few pics of my first rc design. It is a 2 meter sailplane and just finished building it.
Sadly it crashed on its very first flight. I don't know the exact reason but during the flight I lost elevator control and soon after the plane entered into a dive and crashed at the bottom of the slope where we fly, which happens to be a road. The cliff is about 100 meters high or more. I had to run all the way down the cliff (with the help of a friend) to recover the plane before it was stolen.

Against all odds the wing was intact, but the fuselage took serious damage. So I'm starting a new fuselage this weekend. Can't let a minor incident like this to keep me out of the air eh? :D

[BMatthews]

Looks good to me. Off hand I don't see any obvious aerodynamic reasons why it would suddenly dive in like you describe.

Where was the CG located at and did you try running the design through one of the online CG calculators?

[Chrono]

I didn't know there were any online CG calculators. Could you recommend me one BMatthews? That would be helpful.

Anyway I did tested the CG at home and also before flying, as so did several other modelers at the field. It didn't look wrong.

:rolleyes: Mmmm, I forgot to mention. After I examined the rests of the fuselage I found the elevator pushrod broken. You think maybe it broke in mid-air?

[harveyweewax]

Here is a link to an online CG calculator.

http://adamone.rchomepage.com/cg_calc.htm

Nice looking airplane :)

Regards,

Sven

[BMatthews]

Depends on what you made it from and if from wood if it had some very bad grain runout or if balsa if it was super punky.

[Chrono]

Mmm no, it was a dubro plastic pushrod.

[Ricardo RW]

Does the wing have ailerons? I can't see them... If it hasn't have ailerons I would say the wing needs more dihedral.

Besides it seems that the volume of the rudder-fin is somewhat low (vertical volume).

There are some Excel Spreadsheets on the web where you can input the dimensions of your plane so you can check if they are right,

PM me and I can email you a couple of spreadsheets that I have.

Regards.

[BMatthews]

Mmm no, it was a dubro plastic pushrod.

In that case it would have been due to crash impact.

Good call on the dihedral angles from Ricardo. As mentioned if it's not ailerons then a bit more angle in the tip panels would be wise for a snappier turn response.

[Chrono]

Ok, I'll check the size of the surface area of both elevator and fin. In the end I decided on building an entirely new fuselage, this time I'm doing some efforts to keep it as light as possible, trying to keep it strong nevertheless.

I'll tell you how it went as soon as I finish it. :cool:

Thanks for all the advise.