Hey-Santa brought me a model !

coolwings

Happy New Year everyone!
Here's a couple pics of a new model Santa brought for me

Graupner Starjet Twin.

Designed for 2 twin x 400 or 480 motors with twin props.

I had a 90mm fan looking for a new home so I just had to modify ..... couldn't stop myself
Now it's going to be a Star-Jet ! :cool: :cool:

Take a look:

coolwings

Using fan as template, cut square opening between twin tails...
Line with hardwood, balsa trailing edge in middle...

coolwings

Ready for spoiler in front of fan...

coolwings

1/64th (or 0.8mm) birch ply glued to make spoiler....
Width to match fan.

coolwings

Spoiler in place....

coolwings

Sand foam to fit better, glue in, ...
Here's is the view from where the fan inlet will be....

coolwings

Trimmed inlet ring to accommodate new fan wood bearers...

coolwings

Add stickers, finish normal building instructions.
Fitted RC and servos as instructions.
Ready for fan installation and wiring up....

coolwings

Model finished ready for fan tailpipe and motor next.
tailpipe will be either a coke bottle trimmed, or a card cut to shape (courtesy of Kelloggs cornflakes ! ) covered with silver iron on film so as to look its best.
I am at this stage now.

tallus

You must have been a good lad all year Coolwings :-)
I had to bribe the good people at Visa for my pressie :P
That's pretty impressive looking it must go like a rocket when it runs :-)

coolwings

tallus wrote:

You must have been a good lad all year Coolwings :-)

Dunno about that Heh heh!
On the credit card front - I'm afraid to touch it, it could burst into flames it got used so hard before xmas!

tallus wrote:

That's pretty impressive looking it must go like a rocket when it runs :-)

With the 90mm fan it will fly better than the normal propped version while at flying speed,
but
when it slows down it will be slower to accellerate again, so hand launches are more tricky, (or riskier, depending on how you look at it). So I will fit a bungee hook this afternoon and go for aircraft carrier style catapult launching procedure

Most of all I think IT REALLY LOOKS COOL, so I can't wait.
Flying time tomorrow:D

More pics once I get the tailpipe and hook on, then I gotta balance with the batteries I have here - can't afford new ones so a 12 cell GP2200 pack is going in there whether it fits or not!

Does anyone know how Do Who's "Tardis" is bigger inside than outside?
Could do with some suggestions.....

g5hn710m4xpdwy

nice u must get some pics of it when its running speaking of which i can post my pics now

coolwings

Flunked Your Pics - Do it ! - Let's see em ...

tallus

Yeah flunked come on dude !

g5hn710m4xpdwy

ok.. ok... i will try my hardest to get em tonight :rolleyes: its a family digi cam it moves around alot at this time of year

vectra

coolwings wrote:

Happy New Year everyone!
Here's a couple pics of a new model Santa brought for me

Graupner Starjet Twin.

Designed for 2 twin x 400 or 480 motors with twin props.

I had a 90mm fan looking for a new home so I just had to modify ..... couldn't stop myself
Now it's going to be a Star-Jet ! :cool: :cool:

Take a look:

Looks cool
Why not put twin brushless motors in there

coolwings

Well I had one 400 size brushless - couldn't justify another with all the other stuff....
But I have a 90mm fan and another bigger brushless which is about the power of 2 and 1/2 400 brushless systems, ...so it had to be the bigger moter with single fan.
As far as the fan vs props was concerned - I have a thing for jets and they are so easy to do with fans - that decision was no contest.

tallus

they look spectacular in the air too

coolwings

Yeah
And you don't have to have a brushless motor either
provided the ducts are short and the plane light (both ok in this type of model) an ordinary brushed motor will do fine, but die slowly under the strain.
Here is a video of a Multiplex twinjet (almost the same model as the Starjet) and this one has a speed 600 motor and 12 cells....
###
Uh Oh - link gone
I'll put it on my own page in a minute...
Here:
http://uk.geocities.com/norm_flyer/edftwinjet.wmv

tallus

That's pretty cool

mugenextreme

i like that one coolwings, the ones in the vid would they be the standard engine config or would they have had your mod with the large single engine

coolwings

AFAIK the one we see takeoff & land is converted to EDF with an ordinary speed 600, and the one in the air is the standard twin prop version with twin 400s or 480s, sounds like 400s to me.
The jet one takes off second and lands first which kinda confirms this cos the jet would use the power up faster.
I've wanted to have a go at this mod since I saw it fly....

mugenextreme

how usable is a plane like this in the irish weather (wind wise). what sort of price are u talking for one rtr just out of interest

coolwings

It will be better on windy days because that will make takeoffs and landings slower and easier, with a model that will tend to come a bit fast.

Price - it was in a sale last Autumn for €50 (reduced from about €115 I guess) and my wife bot it and kept it till xmas

What I've put inside is
2 x micro servos at €19 each, and a €50 impeller. The engine will be a brushless I already have €120 if I had to get it today, and speed controller about the same. The battery I have already - it goes in quite a few models now)

If I was doing it tomorrow,I would choose the Multiplex Twinjet, it is just as good and costs less.

coolwings

OK I have had to leave off for too long.
But finally got a building session in.
The fan I am using is the Aero-Naut Turbo 1000 fan. It is oldish, but inexpensive and very light in weight, so that's why I decided on this one in particular.

BUT - It has no mounting flange. So I had to put one on it.

I cut 4 pieces of 1/2mm epoxy sheet (could have been plywood) and some carbon roving (twine) and epoxied the flanges on, while all was taped into the plane, so they will glue in the right spacing.

Now all is set and hard, I have removed it from the plane and taken off the tape.
Here are a couple of pics....

coolwings

Life has been busy and as a result I have been off the job for too long.....:(
So I got the Starjet back onto the building board last night.
Impeller flanges are now glued on, and glassed with fibreglass and thin cyano glue.
Two strands of carbon fibre rovings added over all to make nice and rigid.
Then placed onto the mount and drill through fan-flanges and mount in one go (so holes line up later).

Here are some pics:








Next session is motor installation

coolwings

Well it's raining and I'm off work - so out with the building board

First the motor goes into the fan.
then the intake rings (cut in half) are glued back onto the fan....

coolwings

Then it's into the model, and make an exit (efflux) pipe.
the ideal is for a reduction in diameter of 10% - 15% to maximise final airspeed.
I went for about 8-10%, constriction...
This will give more static thrust for hand launch takeoffs. I guess it will be fast enough anyway he he.

the "pipe" is cut from 3-D mylar stickyback covering.

Taped onto fan unit for test fit, take off, recut, and so on, until it is a perfect match.

Here we are ready for a little more permanent gluing.

coolwings

Too late to test fly today (it's clearing up outside ).
I've still got to make a nice resting place for battery, and balance so centre of gravity is correct.
But it won't be long now!

g5hn710m4xpdwy

I want to get/make a plane now;) nice work so far

tallus

It looks pretty sweet !

coolwings

Did first weight - power tests...
10 cells - weight 1500g - 255 watts = not interesting.
12 cells - weight 1600g - power ? dunno still to measure
14 cells - weight 1700g - power OMG ! This is the one !!!
Exact measurements to follow, I had to stop as the spinner came loose. (Threadlock next time)

tallus

Excellent ! will we see video ?

coolwings

Video - of course - nothing less would do !

A few more pics....
Using paint to make the fan inlet fairing become a finished part of the jet.
Nothing spaceage required - just a brush and cadmium yellow artists acrylic from the tube.

Trial fitting different cell counts ... this shows the 10 cell pack, which was later discarded in favour of 12-14 cells on power considerations.

coolwings

I flew it this afternoon.
Wonderful!
Fast and steady like it's on rails.
The coolest whistle from the fan.
Unfortunately my Tx battery alarm began to sound and I had to cut the maiden flight short.

g5hn710m4xpdwy

she looks damn nice too got any pic of the finished product?

coolwings

Next time out I'll bring the camera.

It looks like something from Battlestar Galactica shooting across the sky !

tallus

dude give me a call too! My cam is working again ! and I have a dvd for Patrick of his various models from last friday afternoon.

coolwings

Right-ee-oh. Will do that.

tallus

sweet so :-) once it's not a friday a sunday or a tuesday

coolwings

Here are some new pictures of the finished job.
I had a need for ballast in the nose to balance the CG correctly.
So I used an opto type controller and a receiver batery became the ballast.

This assumes I continue with the 10 cell packs shown installed.
It would be nicer with 12-er packs, but I've got 4 of the 10-ers, so this is more convenient.

Efflux tube constricts the 90mm duct down to 85mm, and provides about 10-12% extra speed.

First flight report:
Hand launched (I've got to put in a bungee hook) , had a 8 foot "sink" while it accellerated and got "onto step", then whoosh - out - away - up - WOW!

I'll try to get a video for the next flight.

Coolwings
:cool: :cool: :cool:

tallus

Dude she looks fast just sitting on the ground !!

g5hn710m4xpdwy

nice is there seperate bats for the reciever so the main drive batts dont drain so fast?
nice work anywho

coolwings

If I had a 12 cell pack it would have more power, and also there would be no need for lead in the nose.
But I've got 4 x 10 cell packs now, and it seemed easier to use a receiver battery and a little lead to get the balance right.
Maybe I will convert my packs to 12 cells later, if I still have the plane.

Plug

They look hard to fly, are they, I saw videos of other models that are simualer and are fierce fast and giddy:eek: It looks class non the less;)

tallus

Plug wrote:

It looks class non the less;)

I have to agree, makes me want to go out and buy one

coolwings

Hopefully I'll get the time to put a bungee hook into it tonight.
Then I can catapult launch from flat field and fly at the Kestrel club tomorrow.

syl77

Looks fairly neat coolwings....what size motor is in it.
just finishing off a high-speed prop kit plane...delta wing..
will post pics when done...

coolwings

syl77 wrote:

what size motor ...

Brushless Kontronik 600 size, sp wind, 2000rpm per volt.

syl77 wrote:

just finishing off a high-speed prop kit plane...delta wing..
will post pics when done...

Mmmmm .... deltas ! Me likes deltas ! They're fun...

Looking forward to the pics.

coolwings

Not my Starjet video...but very very similar in the air.
http://www.wattsup.co.nz/videos/EDFTwinjet.wmv
This is a Twinjet with same conversion job, but with lipoly batteries it came out lighter.

I had one Starjet EDF flight similar (same power, same speeds, same whistling sound) to this vid clip last Sunday (sorry no camerman), but on the landing approach I clipped a solid object and cracked one wing and the nose. ]
Did a quick fix, which was not strong enough for the takeoff stresses and another bumpy landing resulted. :eek:
So (lesson learned) I won't fly it again until proper repairs are completed.