Converting Pusher Parkjet to EDF

[solentlife]

We all know the Hobby King Parkjet ....



Small, lightweight and fast.

I have spare 50mm 5 blade and a 51mm 7 blade EDF units and thinking about a conversion ..

I would like to set the EDF unit DOWN into the fuselage at rear instead of on top as with the Flycat. But worried that setting the EDF unit down into the fuselage will destroy a significant amount of air intake and subsequent thrust.... by way of the thickness of foam across the intake.

Is it possible to regain intake volume by removing a section of fuselage ahead of the EDF unit so there is effectively a slot in front of and allows the air to fill the intake. Question is how long a slot in front of the intake and is a 50 / 51mm EDF sufficient to make a respectable flyer of the Parkjet ?

I'm thinking that if I taper the foam as it nears the intake ... the slot can be minimised ...

Please any ideas / comments / maybe you've converted a parkjet yourself ?

My 51mm EDF has a 4890KV inrunner fitted and has mounting fins suitable to fix to the Parkjet ....

http://www.hobbyking.com/hobbyking/s...3-00107-7B.jpg

[Glacier Girl]

Copy of the old Electrajet which in turn was modded into the Tbird/Firebird EDF.
Take a look at how it was done, would be a drop in fit for the Park Jet.

http://www.rcgroups.com/forums/showthread.php?t=536666

I even built a Stryker using the set up from my old Firebird.

[solentlife]

Your Stryker looks remarkably similar to a parkjet ...

Seeing that Firebird and your Stryker ............ makes me want to get on and try it out with EDF. I realise that I won't get the speed I'm getting from the Pusher version - but still - it's worth a go. There's something about a screaming EDF .....

What size EDF unit was it ?

I have a 5000kv EDF motor suited for 55 / 64mm (2810 Turnigy) as well and wonder whether a 55mm unit maybe better ?

[Glacier Girl]

It was a 66 mm unit. Could be run with either a 6 or 3 blade fan.
Most likely an old Wattage fan, similar to what was used on the Eflite Airliner.

And I'll be honest, it was a slug in the air. And more noise then anything else.
I eventually yanked it and installed a Wemo 6904 set up. Then it cooked.

Hmm, maybe look at something like the Change Sun 70 mm 10 blade.
With a HK 2855/2100 kv motor on 4S it pulls around 35 amps, and 500 watts.

As a bonus depending on how stupid you wish to go, there are folks running this set up on 5 and 6S. Should be more then enough power for ya.

Oh and with the CS fan, you'll loose that banshee scream, you'll get a more turbine whoosh from it.

[solentlife]

banshee scream is fine with me, in fact I need it for the doppler app to gauge the speed.

I think the scream adds to the adrenaline and impression of high speed ...

My Parkjet will receive the 50 or 51mm EDF unit ... with high KV motor and 4S .... so it should get a reasonable turn of speed but nothing excessive I reckon.

The next question is .......... does it need an exhaust tube or will just the EDF body be enough ? I'm hoping that I don't need to add a exhaust tube as I want to keep weight down.

It's more out of interest really to see what she does. Given that the Jpower 50mm EDF's go quite well - I'm hoping that the parkjet being a little lighter and thinner wing will be just as good or better.