Edf thrust!
 

hello guys!

i'm going to build an rc EDF plane and i have a question....
what thrust has to have the EDF so it can flyes?
for example if it weights 300gr-500gr-750gr-1000gr??

thanks a lot!

There's so much information and knowledge out there on EDF setups, that you would probably be best off to just show/post your plane's specs. Folks would list various known good fan/motor specs for the plane, with that info.

From my (limited) experiance with small scale EDF jet models I've found that as a rough rule of thumb, typically, I needed a minimum thrust equal to one third of all up flying weight.. But that would be the absolute minimum to fly, dont expect good performance. For 'jet like' performance on scale type jet models you want static thrust to be 75% plus of all up weight (the more the better).
This is only a very rough guide because actual thrust required depends on many variables. For instance; heavily wing loaded fast flying scale jets need high thrust/weight whearas slow flying lightly loaded models can fly on much lower power.

Steve

I'm thinking of buying an 64mmEDF with an motor of 520w and 1100g thrust...
but i don't know the weight of the plane.... so i would like to know how the flying weight-thrust works so i can buy materials that wont be to heavy...
the jet type will be an L-39

There is always an easy answer to the question of "how light should I make my plane".. the simple answer is: 'as light as possible'. Lighter weight will always give better performance and safer slow speed handling.

Steve

i was thinking to use depron as main material....
but because i would like to have it in more detail i change my mind and i start to thinking of balsa and carbon fiber.....
it will be over weight??

You really need to post some further information so anybody can give you a factual answer.

How long is a piece of string? What about if it's made of twine instead of wool?

This community is truly amazing with their knowledge levels, but they will not give you any information if you can't provide some basics yourself.

What size, what materials, what additonals (retracts, etc), do you have plans to show?

It's certainly quite possible to build a very light model out of balsa, there were plenty of lightweight model around before anyone even invented depron;)

If you define what you want from the model e.g. high speed screamer, low speed 'floater', general sports model.. etc etc that would help.. Also what's your previous building and flying experience, have you done this sort of thing before?. And what size of model do you have in mind?
?????????

the plans are the ones shown in foto...
the length i will make it is 66cm and i dont now yet wich materials to use....
any help?

my fling expirience is very little... ive flyes only a heli and a cessna before....
my builting expirianse is most in boats with materials like fiberglass and balsa....

Scale EDF fast jets are about the hardest RC models to fly you could pick. If you are not a very experienced Rc flyer then there would only be one outcome from trying to tackle a plane such as this.. unless you were incredibly lucky you would write it off on it's first flight. My strong advice would be to pick a very different model to hone your flying skills.

if you are determined to proceed with this one then 660mm is really too small for the EDF unit you have. this would produce a model with very low wing area and so high wing loading which would be very fast but also very hard to fly. i'd advise to make it larger, maybe 80cm span, possibly bigger if you build light.

Steve

80cm span was a guess but a search on Google indicated i wasnt far off..

Here's a 64mm EDF L-39.. it just happens to be 80cm wing span:http://www.cmldistribution.co.uk/cml...tId=0000004543

And an L-39 powered with a slightly larger 70mm fan.. it's 89cm span: http://www.cmldistribution.co.uk/cml...tId=0000004543

thank you very much for your advise!! in case i change the edf with smaller would be the 66cm ok??

A 55mm fan usit would be about right for a 66cm span.. You would be aiming at something similar in size and weight to the electrifly L-39: http://www.rcgroups.com/forums/showthread.php?t=1005952

i see..... so i will change the EDF with a 55mm and i will give a shot.! ;)
so what about the materials? which you think is better?

PS.. i notice that you said 660cm LONG if you really mean 'length' (from nose to tail) then that would only give a wing span of around 50 -55cm. For a plane that small you would be looking at a micro 50mm EDF unit.

Be warned...Smaller model can be harder to fly than larger ones, especially fast small models!

If i were building it I'd do it out of balsa, but that's because i've been using balsa for the last 40 years and i like working with it. With the correct use of materials I'm sure it would be possible to design and build a very nice model out of balsa or foam, it depands on your preference.


Steve

all right! :) thank you very much!!
i will try to built it with balsa and maybe some carbon parts....