dieFluggeister

The 1/2A version of the Shrike calls for a basic Speed 400 motor and a 7 cell battery pack. I'm looking to bump it up a little in performance. Can you guys recommend a solid engine, battery, prop, combo as a speedster upgrade?

vicman

My Feedback: (10)

You meant to put this in the electric side...right?

dieFluggeister

Heya Vic,
Sheesh, a guy cant post anywhere without you finding out about it...

Yep, looking to go electric with this one.

Matt Kirsch

My Feedback: (21)

Start with a 3S LiPoly in the 2000-2500mAh range. Then for speed you need an inrunner such as the ElectriFly Ammo 24-45-2900kV motor, propped to draw around 20 Amps.

jonnyjetprop

My Feedback: (3)

Mega 16/15/5 and an APC 7x5 prop. On 3s pulls 25-27 amp and pulls great.

Mega 16/14/4 and an 6x4 or 5x5 prop would give better speed at the expense of some thrust.

John

BRETTMAN

My Feedback: (11)

hi,what size esc would you use on that motor with a 6x4 prop thanks Brett

themanimal

My Feedback: (1)

you really need that much motor and battery to fly this thing? I am just putting one together as my first speed bird. Any idea what kind of speeds on the straight speed 400 motor?

I'm looking for a decent inrunner to be powered by my 2cell 1200 lipos.

Dr Kiwi

I can't imagine the stock 400 getting you more than ~30-40mph pitch speed and scarcely more than 8oz thrust - even if you push 12A or more on 2s or 7-cells through it.

With only 2s and 1200mAH (if they are 10C) you can only extract ~10A (70W) - not a lot! A Mega 5-turn might be okay? http://www.hobby-lobby.com/mega_brushless.htm

themanimal

My Feedback: (1)

Just when I thought I had a handle on electric flight, this project is throwing me for a loop. I thought that being a light plane, I wouldn't need a motor with a whole lot of power.

It seems that others (and motor calc.which I struggled through) are saying 2100 batteries so I guess I will be using my 3 cell 15c 2100 for this project. I was hoping to keep costs way down as, like it or not, many shrikes become lawn darts.

Motor calc is telliing me to put brushless motors in the 40 amp range in this thing... is that right>?

ARGHHHHHHHHH[][X(]

Dr Kiwi

You don't NEED that much - using the rule of thumb of 100W/lb for decent performance, you should be able to get really good performance on this 19oz airplane with 120W (certainly with 150W) - that's 15A or so max.

H-L says the Mega 5-turn gets you this on 8-cells: 5 turn: 12,800 RPM direct drive with 7x4 prop, 8 cells, 16 Amps, 23 oz. thrust.

Going to 3s and a 5"-6" prop should keep the amp draw about the same. 150W, 1:1 thrust/weight, maybe 60mph pitch speed - you should be good to go!

themanimal

My Feedback: (1)

oh dear, sooo much info for such a little plane.

This is wHAT ANOTHER GUY SAID ON WATT FLYER...http://www.wattflyer.com/forums/show...t=11087&page=2

Quote:
Originally Posted by pdxmonkeyboy2002 View Post
I heard that the speed 400 would only get you about 40mph. I am looking for something in the 70mph range....

Heavens no....someone is using the wrong prop.

On 8 600AE nicads cells (it was that long ago!) with a 4.7x4.7 prop I was easily in the 70 mph range......

Pitch speed for my setup was 68mph and it was exceeding that. I know that sounds impossible but sleek fast airplanes regularly exceed pitch speed - trust me....

And at that speed and size it required almost constant turning.....

If I were building this model today - I would not use a speed 400 motor.

Rather I would use the hot wind custom CDR motor or one of the little screamers with a small light 3s Lipoly.....

10-11 amps on one of those with 3s voltage and a 5x5 prop should put in the 80 pitch range and it will likely go a bit better than that. All with a very light setup....might actually make that plane fly well!

Mike

so as you can see, as the confusion mounts, I am thinking of just sticking an .049 on it and launching the thing......

AndyKunz

I'm about to start on my second Speed 400 Shrike. The first still flies with a Mega 16/15/4 and 7x5 (trimmed to 6"), 3S 2100 20C, 40A ESC. It's a rocket and has unlimited vertical as well, and I have not radared it but comparing it to a known-good 100 MPH model, probably about 115-120.

No, you don't need that much power, but it's what I'm putting in the second one, too (using E-Flite EFLM2005 instead, more speed!). There's no such thing as too much power!

BTW, the first is over 2 years old and has lots of flights on it. A good launch at partial throttle is the key to longevity. I think most Shrike's are lost in the first 30' of flight, usually due to torque. Launch it at part throttle, then throttle up once the plane is actually flying.

Andy

AndyKunz

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