Spark Finished!!
 

Guys

Been a bit busy to post anything before but I had two prototype Spark kits arrive beginning of last week. We hope to have them flying in time for our St Athan fly-in and then JetPower.

Kits look great, the wood work is not finalised and there will be more detail work once the production aeroplanes arrive.
Airframe weight out of the box is 1685grams (3.7lb) on my two kits. Area is just short of 500 sq in
I'll post more shots soon, as the DS 75 units arrived on Friday.

Initial testing will be with a set of Thunderpower 10s 5000EX cells

Dave W

RE: Spark arrived
 

Looks real nice. Keep us posted. Do you know what fan unit and speed controller you will be using? Are you you gonna try different combos? Good luck!

RE: Spark arrived
 

Jetdktr

I'm using the new DS75 fan-doubt that I will experiment, but other people might chose to.

Attached pixs along side one of my EVF units for comparison.

Dw

RE: Spark arrived
 

I would say go as light a setup as you can. the 75 is a cut down 94. So it has all the big motor big input shaft big power sytem like a 94, except with 2/3ds the power, so lighter is going to be better. In my opinion they dont have the expierience, and havn't developed the plane enough to pass it out to poeple in the EDF market, just by sheer fan choice alone shows it. They sure know how to make a plane though, there construction is perfect for EDF, light and strong. not bashing, just trying to keep it honest for best succes




Barry

RE: Spark arrived
 

Barry

The flying I saw on the prototype showed me it should be fine...it's flying OK in Thailand where it's hot and thin air...so in big fat wet England it should be better.
At the end of the day I have the aeroplanes to test and we will see!

Dave W

RE: Spark arrived
 

well flight envelope it self it great, but even at a recent, very cool event even, it was clearly thermaling. And take off was slow and cumbersome, showing they squeezed the tail pipe down way too much to try and make a slower setup fast. And top speed was not what it should be cause they had the setup all wrong and at or beyond its limit, again trying to fake the fan as being bigger i suspect. Not saying it cannot be drastically better though! I just don't think they know how to set up a fan, and its not too nice to sell somehting underdeveloped that you really have no clue about to poeple. I think they were trying to push the handicapped 75 too much expecting more out of it than it could provide. It wont have the thrust of a 120mm and it won't have the velocity of a 90mm. So best bet is to keep it light in regards to motor and cells and esc, this way you wont see it as a 120 and overpower and over weight it. and along those lines I think your on the money in regards to running 10s. If you do the poor mans math and say 10s kept within 20c gets you 36 volts, then keeping in c rating of cells and having around lets say 100 amps then you get 36x100=3600 watts. this is a good range to be in for that fan. But you should mock up the tail pipe before you final set timing and install it in the plane cause this will change it dramatically. 100 amps on a bench can be 115 amps installed in some cases, leading to over taxing everything. This is gonna be the best bet since they have went and made a plane for an oddball sized fan they know nothing about, you cant go 120 cause inlets are too small, and you cant go 90mm cause there too big and will case drag to hamper speed.

Barry

RE: Spark arrived
 

Will look forward to your post flight posts Dave.

RE: Spark arrived
 

Bob

Yep-talking is just that...it's the doing!

regards

Dave

RE: Spark arrived
 

Guys

Just a couple of Spark photos I found on my camera card this AM. The tail and wing are designed for JR side mount 3301/3328 servos but I used DS161 in my tailplanes and 3401/3421 with side mounts in the wing and rudder.

Dave w

RE: Spark arrived
 

Dave,

Why did they not put the servo boxes parallel to the hinge line? Do you get the movement with that set-up? Dont tell me you are relying on the clevis twisting on the thread?[sm=confused_smile.gif]

Jason

RE: Spark arrived
 

yuk!! looks like its ugly ball links for that one!

my son wants one of these for a Wren 44. be interested in how well it goes Dave

RE: Spark arrived
 

if it holds for one flight he should be ok:D

RE: Spark arrived
 

I had big hopes but it's not sounding to good for this one!

RE: Spark arrived
 

Andrewjet,

I have seen Dave's and the quality is good.I think you will find most of the posts here are humor, uninformed or profits of doom. The Spark is a CARF product and no reason why it shouldn't be to their usual high standard.

Trevor Skedge

RE: Spark arrived
 

Jason

No the links will be locked, the control arms are very short and movement needed not great so the pushrod only moves a tiny ammount side to side. Yes I could have fitted ball links but it's not needed.

Dave

I expect you'll see the turbine version at JP. the MW44 will be perfect.

Andrewjet...keep faith...it's a winner

Dave w

RE: Spark arrived
 

What is the weight of the motor, fan and cells used in the Spark? Just wondering what the weight difference would be with a 44 with a litre of fuel at take off. I am hoping this will be a proper little plane as I have a 44 gold sitting doing nothing at the moment.

Looking forward to seeing it fly at the weekend!

Jason

RE: Spark arrived
 

Jason

I'll remove it later and weigh it for you

Cells weight 1220 grams alone so it will be lighter...plus my Mmmm

Dave

RE: Spark arrived
 

Guys

Ok the Spark is just about finished-can't decide whether to tint canopy glass blue or fit a pilot!

Model with TP 5000 10-s cells came out at 4620gram ready to fly.

Test flight tomorrow at St Athan

Dave W

RE: Spark arrived
 

D,

Pilot with full cockpit detail.

Trevor Skedge.

RE: Spark arrived
 

T

Too late, blue paint came out as pilot weighed 50 grams!

D

RE: Spark arrived
 

Guys

OK I had the chance to test fly the Spark yesterday at St Athan.
Great flying aeroplane, very little trim needed and even with new cells and a speed control set with a high cut off voltage the Spark is rapid!
Slow speed flight was what surprised me, but handling and glide is very good.
In light winds the landing speed is slow. Rolls are axial and knife edge has only a small couple.

Nice!

Dave w

RE: Spark arrived
 

First flights at St Athan jet meeting.

Flight times are 4-4.5 minutes with 5000mAh Thunderpower 10s packs.
Slow speed flight is the surprising thing as everyone said the wings are too small, yet it glides really well and slows up to land on our 90yard grass strip!

Dw

RE: Spark arrived
 

Thanks for post flight impressions and photos Dave.
Now a few questions:
What type and size wheels did you use?
Is the nose gear opening precut and no door provided?
I would think it would be simple to rig the nose door to help clean up the model in flight?
What is you RTF weight?
Thanks,
Bob

RE: Spark arrived
 

Bob

I used Eurokit 60mm wheels-no brakes and a Cermark 57mm nose wheel

The nose opening is pre cut...or was on my two pre production kits-I'll ask about production.
A nose door would be possible but we feel that it aids pack colling which is just behind the opening.

my model is 4620grams with 10s Thunderpower 5000's

Dave

RE: Spark arrived
 

Is the nose opening a rectangular cut out or the out line of the wheel and strut?