It Lives!!!

[ppridday]

YouTube - Wren Maiden

Finally, yes Finally the Wren / Predator takes to the air. Amazing how stable this thing is in the air. Likely due to it being so heavy. It has quite a bit of forward weight even with the tank full. I had to slide the tank back a bit to get it even close to balanced. There will have to be a bit of work there to sort it out.

Hopefully we will get a canopy on vid tomorrow with a bit more light and a MUCH better vid camera. Gotta thank my buddy Kurt BIG time for all the help on this puppy and for all here in the turbine forum for the words of wisdom.


Paul

[riccardoc]

Very nice, I wish I had one. Sounds great:thumbup:

[Silverfox]

Hi Paul

Looks great and I know the smell is fantastic.

Do you know the weight? And what size blades are you using?

Regards

Rob

[Sara]

Well done, Paul! Another Wren doing what it was made for ... it's always rewarding for us when another one takes to the air.

Sara Parish
Wren Turbines

[corona007]

Love the sound!!!!!!!

[DDragon]

Hi Paul,
looks good. Congrats!

Yes, what size blades are you using. When I first had mine flying I was using 720 with the stock predator tail and found it nose heavy. But once I switched to a condor tail and used 800 blades it balanced out.

Deron

[ppridday]

Thanks all. It is a very cool setup indeed. I am running the 720mm V Blades on this. Never thought of the CG changing with the Condor boom and 810 blades on. I am thinking of going this way eventually. Maybe it will be sooner rather than later...

Paul

[Skiddz]

Well done, Paul! Another Wren doing what it was made for ... it's always rewarding for us when another one takes to the air.

Sara Parish
Wren Turbines

A couple weeks and mine will be right there too.. Can't wait just to hear and smell it running again...

Nicely done Paul!

[cbergen]

Which is why "we" (Gary and Troy) went for the long boom and big blades right off the bat. It seemed a better "fit" especially with the weight. Autoing a 16-18 lb heli on 710's or even 720's can be a challenging affair...:):) With 810's, oh man, what a DREAM!!

Looks Good Paul, you ARE bringing it to IRCHA, right?

[rkeith2]

I will attest to that statement on auto's and for more fun do it with a non driven tail :smokin:

[ppridday]

I'll be trying out some type of 'big' blades on this with the Condor boom setup. I will be bringing it to IRCHA as well to putter around with after I get my waiver (I hope). :shock::shock::shock:

Paul

[Bell Bloke]

That's the best maiden Predator flight I've seen. Good headspeed, but not too much.(1750ish?) Good solid engine start, with nice gas mix.. Great to see your creation in the air ppridday!! :-) :-)

[ppridday]

I had a guy tach it for me today and he said it was 1330... :confused: I'm going to get Kurt to tach it again for me tomorrow & bump it up a bit if it is indeed that low. Also I have been getting flameouts after hovering and a bit of doddling around. It is after I land and bring it back to idle. Thinking now that it may be as I 'trim' back to mid which is where the ECU 'readies'. More experimentation tomorrow.... :thumbup:

Paul

[Bell Bloke]

Yes it sounds like its just shutting down, as for your headspeed there is no way that was 1300, maybe he had it set to 3 blades :D Looking good though.

[metalmagus]

Nice first flight Paul. Well done.

The grin from ear to ear says it all.

MM

[ppridday]

Thanks again... It is a scream to fly for sure even though I have just been tooling around hovering and doing fig 8's etc.

I did get the rotor tach'd again today and it was in fact down around 1380. We ramped up the throttle curves at points 4 and 5 to 75 and 80% I believe... (have to check again in the morning on the Tx) Still just as stable but doesn't seem to want to 'fall off' as much and now headspeed is up at 1650 to 1680. I think I am going to try Chris' suggestion and set idle (45K) at low stick - mid trim and flight hover (~70K) at low stick - full trim. It seems like it should work very well and maintain the zip out of the turbine...

More fuel to burn....... :):)

Paul

[DDragon]

I'm running my 800mm blades at 1550 rpm. I'm wondering if I should bump it up to around 1700 as well.

Would that be safe? That thread on loads and blade speeds keep coming to mind.

[Bell Bloke]

Deron what do your blades weigh? I will calculate your max safe headspeed.

[DDragon]

I'm not sure, they are NHP blades. I think there was a thread about this somewhere?

[Bell Bloke]

If they are 190 gram, which I think they are then the max headspeed for the Predator is 1700rpm to 1750rpm max. This calculation is based on very safe oparation figures and 1750rpm on 800mm blades is more than enough for any type of flying. :-)

[helibeli]

What is the calculating formula?

[Bell Bloke]

F = m x r x (2 x Pi x N/60)2

F= force in Newtons
m = mass in Kg
r = radius in meters
N = revolutions per minute

[ppridday]

I had some 720mm Rotortech's that weighed in at over 190 grams... the 800's may be more than that. Best to physically weigh them maybe.....:confused:

Paul

[Bell Bloke]

Yeh Paul is right, they need to be weighed Deron :-)

[DDragon]

Thanks Guy, yes.... I'll do that tonight. I need to check a few things anyway.

I'll get back to you.