depron Jet

thought i would post this up as i have made some progress.

experimental edf jet mk1.
never had much luck with edf's (tried once before)
so all depron with minimum balsa.
65mm edf.

nowt more to say at the moment.
i doubt it will work, but you never know.

Tony
Looks very interesting but I would agree with Eric that the inlet profile does have a big impact on the thrust.
I spent some time and effort with the inlets of my Venom so despite it being bigger and heavier it flies rather better (and at lower power levels) than my smaller lighter Vampire with its poorer inlet shape. Both use the same battery and EDF.

EDFs can be made to fly quite slowly yet have a reasonable performance on a modest power - if they are light enough!

How much does yours weigh at the moment and what size battery will you use?.

motor is wired up and working now.
noisy aint they.

with a 2200 mah 3s lipo it weighs 337gms at the moment.

vtol attempt number 1)

vid87.photobucket.com/albums/k160/arden4...0157_zpsx1rfwwxb.mp4

need to try a thrust tube next and see if that helps.
if not then we scrap the model or try a 4s lipo and see if that helps, but that will add more weight.

Where's the thrust outlets on the VTOL experiment Tony?

Pol.

straight out the bottom of the fuselage, the edf rotates 90 degrees to move from vertical to horizontal.

cant get enough thrust from it at the mo.
makes a good hovercraft though.

need to find the optimum thrust tube length and try again and again.

Tony B wrote: vtol attempt number 1)

vid87.photobucket.com/albums/k160/arden4...0157_zpsx1rfwwxb.mp4

need to try a thrust tube next and see if that helps.
if not then we scrap the model or try a 4s lipo and see if that helps, but that will add more weight.

Lurve the overall look especially the wings and tail but agree that the angles for the airflow look too sharp and would cause turbulence Can I suggest that the side inlets are deleted and the fuzz rear be slimmed down. The nose opened as the inlet as per Whittle Pioneer and lots of others. Least line of resistance etc. I recall back in the early days of DFs there were articles about the design and construction of ducted fan models. One of the concerns was that over certain revs the blades might " CAVITATE " and lose thrust as a result I don't know if this was the case but I know it happens with boat screws.. I admit to knowing only a bit about Ducted fans but did fly a couple in days of yore. F'F Veron FD2 with Veron fan ED Bee And Lavochin La 17 with a Bantam

longer thrust tube and we still cant get enough to lift it.
vid87.photobucket.com/albums/k160/arden4...0158_zpswefbzuxj.mp4
tried a 4s lipo but the extra weight negated any benefits of more power.
there is enough oompf to fly it as a conventional jet, but not for vtol.

hmmmmmmmmmmmmmmm.
time to scrap this one and have a re think.

intake is through an opening in the top of the fuselage so the air has a straight through passage.

still need more oompf.
oh well.
back to the drawing board.

Interesting!
What you need is a Thrust Test Rig to actually measure the thrust of the EDF.
This gives you an idea of how much you have available for the battery, airframe, servos and a control system.
To quote Paul Daniels it tends to be "not a lot"!
You may have to consider using relatively small batteries but running them hard, say at a 40 C rate (60 seconds duration?) to get the required thrust to weight ratio.

i found that if i run a thrust tube that tapers outwards from the edf i can get more lift, not enough to get it airborne though.
i think the model needs to be lighter ( a lot lighter) and maybe a very small 4s lipo is needed.
but that costs money and i am very short on that.
so i think i will be removing the edf from this airframe and starting again with a very much lighter design like a flying wing or similar.
it is definitely a thrust to weight issue.

onwards and upwards, we hope.

Interested to know what sort of control system you intend to use on a single jet vertical take off device.
Without positive control it may have the thrust to lift off the ground but it will crash almost instantly!