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Old Feb 03, 2013, 04:18 PM
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Build Log

Me-262 Dynam twin 70mm EDF


I ordered the new Dynam Me-262 from Nitroplanes a few days ago ... I got it in two days, and it took me a day to build and set up.

http://www.nitroplanes.com/60a-dy8950-me262-arf.html (I used a 5% coupon)

http://www.graysonhobby.com/catalog/...c-134_201.html

http://www.dynam-rc.cn/Products_view_169.html

http://hobbyfly.de/en/rc-airplanes-1...00mm-6765.html

http://www.cmldistribution.co.uk/cml...tId=0000006669

http://www.osmot.net/dynam-me262-ele...ivv238r95as1l7

http://www.brentfordrc.co.uk/scripts...idproduct=3337

http://www.miniplanes.fr/avion-rtf/j...r-p-46640.html

On the model the wingspan is 150cm, whereas the original Me-262 had a wingspan of 12.60m (http://en.wikipedia.org/wiki/Messerschmitt_Me_262), so that makes the scale approximately 12.6/1.5 = 7.9:1 .

The next day, Saturday, I flew it with the CG at 115 mm and it flew fine, it barely needed any trims. I use the recommended 4S 4000 setup and it flies well, plenty of speed for a foamie . My latest CG is now at 130mm (see picture below).

My nosegear steering lingage kept getting undone at the field, so I had to put a collar to prevent that Z-bend from slipping out.

The elevator and rudder linkages (pushrods) were really flimsy, I had to make the whole assembly a lot more rigid to avoid a possible catastrophy on the maiden.

Other than that, it flies like a charm

Edit : Short video clip :

Me-262 Dynam short video clip (0 min 55 sec)


.
Last edited by Herb; Apr 02, 2013 at 12:49 PM.
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Old Feb 03, 2013, 04:24 PM
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Elevator linkage strengthening ... I cut and rolled some stiff pieces of thin aluminum plate, these were later epoxied into the fuselage.

I thought of using some plastic at first, but it just would not be stiff enough to make the pushrods rigid.

.
Last edited by Herb; Feb 10, 2013 at 03:57 PM.
Old Feb 03, 2013, 04:35 PM
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A receiver battery helped with the CG - for now. Maybe later I will move the CG back a bit, the Me-262 did not feel tailheavy at all at 115mm.

I had to balance the rotor one of the two 70mm fans, the other one seemed ok. I just ran it up to test for vibrations.

Dynam claims the motor is 3600kv, and that the fan at 40k rpm provides 2.8lbs of thrust on 4S at 100mph efflux, taking 645W at 46A :

http://dynam-rc.cn/Products_view_101.html

My own measurements are given below ...

The 63mm diam outlet on the nacelle is a bit sub-optimal, it corresponds to > 100 % FSA on a 70mm fan. A 55-57mm outlet would have been better.

.
Last edited by Herb; Mar 17, 2013 at 03:29 PM.
Old Feb 04, 2013, 07:22 AM
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Looks like a fun little jet Herb. I'm finishing up my Ta-152 finally so I'm keen and dialed in on Luftwaffe Camouflage. Twin EDF jets are always fun too.
Old Feb 04, 2013, 02:26 PM
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Hi Eddie, nice to hear from you ... still sanding that Ta-152 ?
Old Feb 04, 2013, 02:32 PM
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On the maiden the elevator control was a bit mushy ... I think the way it's setup the elevator travel is not enough, the tail moment is on the long side, and the moving surface itself is rather small.

I reduced the expo on the elevator a bit to see if I can get a crisper elevator response.

On takeoff it has the typical characteristics of an Me-262, the low thrust line makes it climb at low speed. That effect goes away when it really gets going, so no elevator trim compensation is really needed.

I put a whatt meter to it, and on a new 4S 4000 25C gens ace (fully charged) pack it read 109A at 1580 Watts. So that's 55A and 790 Watts per motor, on a 60A detrum (stock) esc.

So on a light 5.3 lb plane that's ca 300W/lb which is plenty
Old Feb 09, 2013, 08:51 PM
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got to ask hows it fly?
looks nice
all up cost?
Old Feb 09, 2013, 11:07 PM
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Hi,

I've had five flights so far ... it flies very well out of the box, I did not do any modifications or "improvements" besides the ones listed above (more rigid elevator linkages).

Since it's made out of foam it is very easy to fly and lands really easy. When you cut the power it actually slows down very quickly, because of its low weight and relatively high drag from the nacelles.

My CG is now dead on where it's recommended in the instructions, at 115mm. So the instructions are correct. I flew it first with 2oz (60g) of lead in the nose, but today I gradually removed all of it. It shows the typical pitch up of the Me-262 on takeoff, which has nothing to do with CG location. It is due to the low thrust line.

The landing gear seems to hold up well at my weight (4S 4000 setup), and operates reliably so far.

The fans are balanced ok but I think I can get them to run smoother by balancing the fans & motors ... that service is on my list, but first I wanted to fly it !

The esc's don't seem to get hot on mine (4S) so no issues there yet either. For added safety I fly with a separate receiver battery.

The 109 A my setup pulls out of that poor battery means relatively short flights, unless you use plenty of throttle management.

All in all not a bad deal at $194 (Nitroplanes), and it looks better than the freewing one which has a weird canopy and some rather ugly cheater holes.
.
Last edited by Herb; Feb 20, 2013 at 02:42 PM.
Old Feb 10, 2013, 01:17 AM
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i run 6S 3000mAh packs in my helis and iv kinda standerized on that size how would fly on a 6S setup like that?
Old Feb 10, 2013, 01:47 PM
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Nice Me 262 Herb...fastest build than mine
For fun i think I will order one.
All the best from Canada.
J-C
Old Feb 10, 2013, 03:17 PM
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Quote:
Originally Posted by Elios000 View Post
i run 6S 3000mAh packs in my helis and iv kinda standerized on that size how would fly on a 6S setup like that?
On 6S you will burn the motors even before you fly This is a 4S setup...

Quote:
Originally Posted by bidule View Post
Nice Me 262 Herb...fastest build than mine
For fun i think I will order one.
All the best from Canada.
J-C
JC you will like it as a lazy weekend flier. For what it costs you can't beat the price. A bientot
Old Feb 10, 2013, 03:24 PM
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Yesterday I flew it with a CG at 130mm (gear up), and it flies fine. The factory recommended CG is "115-120mm".

If you are not familiar with the Me-262 flight characteristics, you will find it can "jump up" on takeoff.

This is due to two unrelated factors:

a) the thrust line is low on the 262, so at low speed it pitches up due to the fan's torque w.r.t. the center of mass; and

b) the nosegear strut on the dynam is a bit short, so that can require a slight pull on the elevator to pull it off the ground on takeoff.

.
Last edited by Herb; Mar 20, 2013 at 05:23 PM.
Old Feb 10, 2013, 03:29 PM
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Quote:
Originally Posted by Herb View Post
On 6S you will burn the motors even before you fly This is a 4S setup...
so could one get motors for a 6S setup? maybe get some more speed out of it?
thinking about a EDF but id like to keep with the same packs i already use

any other options on edf that would work with 6S 3000mAh packs?
Old Feb 11, 2013, 01:53 PM
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Of course you can get new motors, new fans, new escs etc. to handle 6S. But, more speed maybe does not make much sense in a foam plane with fairly flimsy linkages and parkflier hardware . There are other more suitable airframes for that (eg HET 262, PN 262 etc)
Old Feb 13, 2013, 01:15 PM
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I thought I might play around with these fans ... they are CS 12-blade with an optional alu spinner.

http://www.x-flight.com.hk/index.php...cat1=10&cat0=4

The fan seems well made, the plastic is very rigid. The efficiency, well that's another matter. I will probably stick
with the lightweight plastic spinner for now.

.
Last edited by Herb; Feb 13, 2013 at 01:27 PM.

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