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Old May 16, 2012, 07:09 PM
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The aileron hinges were flimsy and got replaced with better quality Blenderm hinge tape.

The wing bottom was closed up for now.

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Old May 16, 2012, 07:11 PM
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The new or old scissor mechanism strut does not work for the nosegear with the new electric units : the strut hits against the screwdrive motor.

Which means either buying new struts that cost more than the airframe or design a new nosegear strut (here a' la' T-45) that will retract fully into the nose.

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Old May 16, 2012, 07:15 PM
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Here's a picture of the nosegear retract problem, and my solution. Not truly scale, but functional ...

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Old May 17, 2012, 12:11 PM
ken kalynuk, winnipeg CAN
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Hi, my Fly Fly BAE Hawk arrived yesterday. I appreciate you posting all the photos, they will be a big help when I start mine later.

What motor are you using in the CS 12 balde fan and how many cells.
cheers -ken
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Old May 17, 2012, 08:00 PM
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Hi Ken,

Glad you like it ... I am having fun too ... For motor I used a HET 650-68 with a kv of 1250 (see pictures above).

I used my own fan calculator, but a simple rule for the CS-12bl fan is use the kv =1600 that works well on 6S and multiply by (6S/8S)=0.75 to get a kv in the 1200 region for an 8S setup.

I have been a bit frustrated by the whole struts thing, trying to find a set that fits right and works reliably. The old FlyFly ones were 3mm pins, the new struts are longer (!) and now with 4mm pins, and so are the new metal trunion parts. The new struts don't work in the nose at all.
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Old May 18, 2012, 02:03 PM
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The nosegear retracts fine now, fully inside the fuse, although I had to cut out a big chunk of foam.

I also switched back to shorter struts and lighter wheels on the mains. The new wheels weigh a ton , and the struts are too long. And, you can't fit other wheels easily on them because of the way the axle is designed.

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Old May 18, 2012, 02:07 PM
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The ducting near the intakes leaves a bit to be desired ... that round ending behind the canopy will create quite a bit of turbulence.

JePe makes some nice elaborate balsa fairings, but I decided to go KISS on his one. I just cut two blocks of white styrofoam that I will glue in left and right, mating at the fuse centerline (very securely, so they don't get sucked into the fan).

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Old May 18, 2012, 02:13 PM
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My esc sits right on the CG. There's three reasons for that,

a) the battery cables (black, red) need to be kept short as usual in EDFs (the instructions are very clear about this, usually < 20cm) so as not to blow the capacitors, and then the mosfets on the esc from voltage spikes;

b) the esc needs good cooling, so above the duct is a good location, that I used in several other edfs (eg tam f16);

c) the esc I am using (120A HV) is one big chunk of metal and I don't want to have too much weight in the tail (CG problems), so moving it forward right above the expected CG seems like a good compromise.

I also wrapped the motor and power cables in aluminum foil to eliminate any sort or rf interference with the servo cables, which run right next to the power cables.

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Old May 18, 2012, 04:41 PM
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As mentioned earlier, the Hawk gets the new ChangeSun 12 blade fan I got some time ago from X-Flight HK.

The Hawk should be a good testbed for this inexpensive fan, and the fact that the fan is a brick should not be a problem - as the Hawk foam airframe is very light to start with.

The fan blade assembly was not rigid enough to be safe, and the whole unit was badly out of balance.

I re-assembled the fan with Hysol, and re-balanced the whole rotor unit using the same static balancing method I have been using for ten years or so :

http://www.rcgroups.com/forums/showt...1521751&pp=100

The result should (hopefully) be a well balanced fan, that won't vibrate like crazy and destroy the motor bearings in no time

Short video on how I balanced the CS 12bl fan with reasonably high accuracy on a $3 magnetic balancer :

.

Balancing a 90mm EDF Fan (WeMoTec vs. ChangeSun 12 blade) (4 min 14 sec)


.
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Old May 18, 2012, 08:30 PM
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Subscribed. Have you ever noticed that you can go all day without one single phone call, yet, as soon as you receive 1 call, it just happens that another person tries calling you at the same time? This has happened to me many many times.

That being said, I've had a FlyFly BAE Hawk sitting in my basement for over a year now and 8 days ago I ordered the CS 12 blade fan, not even knowing about your build. And were almost going at it the same way. I find it interesting how the FlyFly BAE Hawk has kinda grown stale, yet, you and I will be (or are building) this very plane. I do have some questions so I will be following your thread and hopefully you'll be able to assist me as I go.

Here is my plan.

FlyFly BAE Hawk,
RCLander T-45 struts for the Nitroplanes Composite T-45
CS 12 blade fan
CC HV 120A
Motor (undecided but it needs to be for 6s)
6s5000mAh pack

Can you assist me on the motor choice?

Thanks,

Jon
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Old May 19, 2012, 12:34 PM
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Quote:
Originally Posted by SkylineFlyer View Post
... I find it interesting how the FlyFly BAE Hawk has kinda grown stale, yet, you and I will be (or are building) this very plane. ... Jon
Hi Jon,

I agree, some thirty-plus-page most elaborate build and mod thread evolve to where it seems like the foamie is finally getting ready for the scale masters, then either the grossly overweight and over-engineered thing never flies. Or the maiden comes and the guy loses it to some rather trivial setup problem

I personally think the FlyFly Hawk should be taken for what it is, a simple and very lightweight semi-scale weekend flier that is very suitable (like the real one) for some fine low speed semi-scale aerobatic routines.

As such, I plan to build it LIGHT, RUGGED (see split elevators) and SIMPLE to maintain (simple retracts, no gear door nonsense etc.).

At the same time, it needs to have good power, otherwise the Red Arrows Hawk will scoot around like a lame duck . Nevertheless the power need not be excessive - since the airframe is very light to start with.

It would seem reasonable to me that that target power should be in the 1800-2400W range or so.

My setup is such that I can go up and down in power and battery size by a cell or so (8S to 9S for ex.). This last one is the FLEXIBILITY argument.
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Old May 19, 2012, 12:46 PM
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Quote:
Originally Posted by SkylineFlyer View Post
... Here is my plan.

FlyFly BAE Hawk,
RCLander T-45 struts for the Nitroplanes Composite T-45
CS 12 blade fan
CC HV 120A
Motor (undecided but it needs to be for 6s)
6s5000mAh pack

Can you assist me on the motor choice? ...
I have not run up that fan yet, but I think that if you run it on 6S and you want to pull ca. 100A (which will give you 21V x 100A = 2100W or so) you will need a kv that is in the 1600 range.

To absorb that kind of power you will need an inrunner (forget about outrunners for this fan) motor in the 300g range. The motor can diam needs to be between 36mm and 39mm, the motor length should be in the 60-70mm range.

I myself am using the HET 650-68 motor (see above), but other suitable motors are Turnigys of various types (XK3674, XK3665), other HET motors (like the 700 series), Neu 1415 and 1515 series, Tacon (HobbyPartz), Leopard, Tenshock, JePe type EDF motors etc. etc.

PS. I think those T-45 struts are too small (short) for the Hawk, the FF Hawk is quite a bit bigger than the CMP Hawk.
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Old May 19, 2012, 12:53 PM
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Yeah, I saw the split elevator idea. Very good idea. I built the F-4 and it too had the full flying elevator. It was a very rudimentary idea. If this one is the same way, I'll probably follow your steps. How did you ensure that the incidence of the elevator was correct when you glued it in place?

I thought I also read that you were doing a 6s setup. No?


EDIT:

Just saw your post about my struts.

Oh great, well, let hope that the struts I bought will work.
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Old May 19, 2012, 01:00 PM
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I was looking at this motor, it might be suitable, or something similar to it:

http://www.hobbyking.com/hobbyking/s...dProduct=17735

Mine does have open endbells though, better for cooling in EDF.
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Old May 19, 2012, 01:06 PM
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I saw that one, but they're out of stock on it. Bummer for me. I might have to go the HET route. I didn't want to spend that much on it, but if its the only option, then I have no choice.
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