depron Jet

hadn't got that far simon.
but if it had worked i would have had the data needed to move onto the mk 2 with control vanes in the edf outlet.
bit moot now as it didn't work anyway.

I like the look of the jet Tony, Ref. the fan, the inlet where the air actuly enters the fan is a crittical area, must be a smooth inlet not just the open end of the fan, most of the top qualit fan do a special inlet sometimes as an extra, getting the inlet right will make a lot of difference to the thrust

well i have broken the model up now and most of it is in the bin.
it was too heavy for the thrust.
now we need to think about the mk2.
i need some efecient way of directing the thrust from a fixed fan, yes the harrier did it i know but that is very complicated to replicate in a model.
again we are talking about weight.
HK do a 1600mah 4s lipo that weighs less than the 2200mah 3s i was using ( but that costs money) so that would give more thrust.
hmmmmm thinking cap time.

suggestions accepted.

Tony
You might do better using one fan (or more) for lift and another smaller one for thrust (like the Short SC1) then you don't have to worry about vectoring anything but, and it is a big but,you still have to find a way of keeping the thing stable when its 'balancing' on a column of air!

yes i know simon it's all a big if.

plan b is to not build an aircraft at all, but something similar to the flying bedstead to see if i can get a hover first.

Right here is the crap Pegasus i built to test a theory.



fixed outlets with deflectors inside to direct the airflow ( badly)

weighs 130gms at the moment with the 65mm edf.
with 3s lipo i can get 210gms of thrust.
with 4s lipo we can get up to 310gms of thrust.
now the 3s lipo weighs 190gms, so it dont leave much to play with
but i can get a 1600mah 4s lipo that weighs less then my 2200mah 3s.
soooooooooo
the crapasus engine weighs 130gms.
the depron jet airframe weighs 130gms with 3 servos.
the esc and rx comes in at 50gms
and the 4s lipo (when i can afford it) weighs 190gms.
total 500 gms.
not enough oompf .

hmmmmmmmmm.

i made up an inlet duct for the edf and had another go.



the motor unit has gone up in weight to 140gms now.
so with 3s lipo we got 250gms of thrust.
and with the 4s we are up to 350 gms.
so an improvement by just fitting a duct.
need to think how i can get another 50 gms from the set up now and we might be able to build a light airframe for hover testing.
then we can think about the mk3 setup with moveable nozzles and a redesigned plenum chamber.

Play around with the inlet some more, get it super smooth, it is a critical area
Very interesting Tony

Tony B wrote: i made up an inlet duct for the edf and had another go.

the motor unit has gone up in weight to 140gms now.
so with 3s lipo we got 250gms of thrust.
and with the 4s we are up to 350 gms.
so an improvement by just fitting a duct.
need to think how i can get another 50 gms from the set up now and we might be able to build a light airframe for hover testing.
then we can think about the mk3 setup with moveable nozzles and a redesigned plenum chamber.

Good try Tony Might I suggest smoothing the intake and removing the obvious step or ledge I also remember some narrowing taper had given extra thrust by building up some pressure immediately before the nozzle outlet. A bit like squeezing the end of hose to project the jet further. I don't know the ins and out exactly but I think there details on line

Tony
For maximum static thrust I would avoid a 'built up' inlet all together and use the EDFs own bell mouth.

What 65mm EDF is it that you are using?

no idea on what make the edf is as it was given to me and it does not have a duct as standard.

still i now have ideas for the mk3 set up, so i might just redirect the outlets on this one and fit it into an airframe and see if it will fly ass a conventional aircraft.

well i made up a rig so i could test it's thrust a bit better.
came out worse than i expected.




with all the gubbins the motor had to lift 169gms plus the loading i put on.
working up in increments on a 4s lipo it stopped lifting at 120gms.
so that only gives a total thrust of 289gms not the 350 i had with the old testing method.
so this one is toast and we go back to the drawing board.

Try turning the 'see-saw' balance around the other way, so the fan unit is in (more or less) free space, away from the interference turbulence of the table, then balance it with the 'other end' of the balance on the scale platform, zero the scales, then apply the power, so the scale is reading the increase in pressure, not the decrease.
If you balance the 'saw' with equal lengths either side, the scale will be reading 1/1 (minus friction of the pivot), make it two to one, and divide the weight by 2, etc!

lost me there Eric, remember i am not a scientist but an idiot.

Like this, if it works! -