Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
October 20, 2017, 10:59:22 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: [1]   Go Down
Print
Author Topic: Freewing Me 262 (upgrades and whatever)  (Read 767 times)
0 Members and 1 Guest are viewing this topic.
Konrad
Platinum Member
******

Kudos: 27
Offline Offline

United States United States

Posts: 1,602


Topic starter
Measure twice cut once



Ignore
« on: June 06, 2017, 12:17:10 AM »

Last night I was wasting time over at MotionRC’s sales forum "Hobby Squawk” and ran across some discussions on upping the power in the Freewing Me 262. I have to admit I was amused that it has taken this long for Freewing to update this fine model. And puzzled that they chose to "upgrade" by down grading the power system!

I’ve been flying an upgraded Me 262 for close to two years now. I need to be clear that the Freewing Me 262 does NOT need any power upgrades! But as I am flying mine at an altitude of 6K feet plus. I felt I might want to regain some of the power I was loosing to the rarified air. With the stock 3 year old 6 bladed power system I was pulling 92 to 94 amps after a 10 second motor run. Again I have to admit the flight performance from the stock powered Me 262 at 6k feet was more than adequate.

My upgraded power package is a pair of HET 2W-27 2500KV inrunners driving 9 bladed WeMoTec 70mm Evo rotors. I had calculated that the stock 60 amp Hobby Wing ESC would still be suitable for the job, so they are the same as the original set up. Now I am using the stock 70mm Freewing plastic housing that came with the 3 year old Me 262. This unfortunately result in less than ideal rotor tip clearances. But as I didn’t want to fit a set of WeMoTec housing into the nacelles I choose to take this aerodynamic efficiency hit from the large tip gap. Also as these and the WeMoTec housing are plastic I added finned heat sinks to the motors. I took this opportunity to use the heat sinks to stabilize the rear of the motors. With the same batteries (old 4.2v cells) the HET/WeMoTec set up is drawing 118 to 120 amps. This results in a huge power increase of over 25% at the battery.

Now as a quirk of efficiency (this has to do with where the airframe drag and power curves cross) my actual flight times rose by approximately 80%. I actually fly at just over 1/4 throttle stick and still have more than enough speed and power for most aerobatic maneuvers. I only need to go to full power for those long verticals. With the 6000mAh battery I almost have a 1:1 power to weight ratio. So she get rather small in the up lines if I want. I now get flight times of 5 minutes with turn and burn flying and still have aprox. 20% left in the batteries. Yes, I was able to fly close to five minutes with the old fans but these would have been rather boring low energy flights.

Now there is a real danger, it was also present with the the stock set up. Since the thrust comes from under slung pods and there is so much available it is very easy (in fact likely) that as power is added at slow speed that it will push the nose up into a deep stall. Do NOT add full power at the beginning of the take off roll or after a stall maneuver. Wait until the model is at flying speed before adding full power, or any power above 1/2 throttle. Many Freewing Me 262s are lost as the pilot adds full power trying to get out of a stall.
You can even see it at the beginning of this You Tube video with the "low power" 6 bladed fan at 6K feet altitude.
https://www.youtube.com/watch?v=qKGhHF7Ow7o&feature=em-upload_owner#action=share

The stock Freewing Me 262 has a construction flaw in that the flap's torque rod is inadequately supported which allows it to bow when load is placed on the flaps. While correcting this flaw (adding bearing support at the very ends of the torque rod) I decided to correct an other glaring flaw. The real full size Me-262 does NOT have split flaps. Watching the real Me 262s flying in and out of Everett made this unacceptable for my scalish model. So I took the opportunity to correct this gross oversight.

Also those small ailerons out at the tip are prone to adding a lot of adverse yaw. Freewing should show in the manual to place the servo horns slanted forward by one (or more) spline of the servo output shaft. As Freewing often cheaps out on the length of the push rods, I had to use a set of Park Zone push rod for the aileron push rods in order to reposition the servo arms. Actually it is a good idea to upgrade all the push rods on the wing with these as they have a much finer thread pitch for much finer trim adjusts. I’ve also added a rudder mix with about 12%, the rudder is small. This set up allows for real axil rolls even with the under slung power pods.

I don't know what Freewing was thinking, the power system wasn't the issue. Most pilots have been complaining about the flaps, so in Freewing's wisdom they added the battery sucking 12 bladed fans! I saw a Freewing Me-262 here at sea level were I thought the pilot had mis-engineered the power system converting over to the 12 bladed rotor when he only had 90 seconds of run time (the Freewing 12 bladed fan has very poor performance compared with the WeMoTec Evo rotor).
http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=21998.0

I'm shocked to learn that the 12 bladed 70mm freewing fan assembly is now stock! Somebody at Freewing must have stock in a lipo battery company!

Now there is a fatal flaw in the Freewing Me 262 design! That is there is little or no air flow across the ESCs! The ESC cooling grills do allow for the opportunity of air entering the ESC. But as there is no outlet the best we get is some turbulent air exchange. The proper fix is to open up the motor lead channels to the engine nacelles. And shape the tunnel outlet to allow the high velocity air in the rear of the nacelles to draw air from the ESC compartments (ref. Bernoulli)

All the best,
Konrad
Attached files Thumbnail(s):
Freewing Me 262 (upgrades and whatever)
Freewing Me 262 (upgrades and whatever)
Freewing Me 262 (upgrades and whatever)
Freewing Me 262 (upgrades and whatever)
Freewing Me 262 (upgrades and whatever)
Freewing Me 262 (upgrades and whatever)
« Last Edit: June 06, 2017, 12:29:41 AM by Konrad » Logged

Cut it twice and it's still too short!
Konrad
Platinum Member
******

Kudos: 27
Offline Offline

United States United States

Posts: 1,602


Topic starter
Measure twice cut once



Ignore
« Reply #1 on: June 07, 2017, 11:33:37 PM »

Forgot to mention that after going with the plain flaps verse to out of scale split flaps, I've been able to take out the rigged 1.5 mm washout I had in the ailerons. The plain flaps act as washout on the wings, but only when deployed. This allows the whole wing to perform much better when cleaned up for high speed flight. Yet protect the airframe from tip stall at low speeds. With proper Center of Gravity and control set up this Me 262 can land real slow. Be aware that as with all swept wing aircraft cross winds are a bit tricker than with straight leading edge wing aircraft.

Freewing you were correct in that the 70mm ME 262 needed and up date but the addition battery cooking 12 bladed fans was not one of the needed improvements.
Logged

Cut it twice and it's still too short!
Hank G B Z
Silver Member
****

Kudos: 2
Online Online

United States United States

Posts: 157



Ignore
« Reply #2 on: June 12, 2017, 01:56:08 PM »

Konrad,

    I didn't know there was a flying 262 in Everet. 

  Nice fix on the flaps.  They do look way better.  I wonder why Free Wing did split flaps?  I would think Plain flaps are easier to mass produce over the split flap.  If possible you should make youtube video showing how your 262 flies versus a stock one.  People understand performance improvements when they can see the improvment.

Hank
Logged
Konrad
Platinum Member
******

Kudos: 27
Offline Offline

United States United States

Posts: 1,602


Topic starter
Measure twice cut once



Ignore
« Reply #3 on: June 12, 2017, 05:28:29 PM »

Konrad,

    I didn't know there was a flying 262 in Everett.  

  Nice fix on the flaps.  They do look way better.  I wonder why Free Wing did split flaps?  I would think Plain flaps are easier to mass produce over the split flap.  If possible you should make youtube video showing how your 262 flies versus a stock one.  People understand performance improvements when they can see the improvement.

Hank

Yep, they were so common flying in and out of Paine Field, we often didn't even look up from our tasks trying to certify the 787s. I will say you had to give them a second look as they did look like the old 737-200 out of the corner of your eye.

Why Freewing went with the split flaps is beyond me! It just goes to reinforce my contention that Freewing is little more that just a plastic house trying to keep the ovens running. The split flap have been a major bone of contention as they are very thin and warp. The inboard ones always lagged the out board ones. And they aren't even close to scale. Looks to me to be a plastic house manager just wanting to make product to keep his oven running. Maybe there is some truth to the claim from MotionRC that they are helping Freewing focus on making better products. I wouldn't bet on it but we can only hope. Freewing definitely has needed some help in the execution of their product.

As to performance I know "pic's or it didn't happen" is the web motto. Or in modern times the ignorant masses want to see video. To show how much different the performance is I'd actually need to fly two models head to head in the same video otherwise perspective is lost.

All the best,
Konrad
« Last Edit: June 12, 2017, 06:08:49 PM by Konrad » Logged

Cut it twice and it's still too short!
Hank G B Z
Silver Member
****

Kudos: 2
Online Online

United States United States

Posts: 157



Ignore
« Reply #4 on: June 12, 2017, 07:16:23 PM »

Konrad,

   Good Point on the video.  Sounds like If you found a stock 262 then getting a video would be hard because the stock one won't have the same flight time any way.  Or more likely people would think yours is stock then be sorely disappointed with the performance of their model. 

    I know you keep your model in Co but i'd love to see it at my field.  The EDF guys would go bonkers seeing the performance you describe. 

Hank
Logged
Konrad
Platinum Member
******

Kudos: 27
Offline Offline

United States United States

Posts: 1,602


Topic starter
Measure twice cut once



Ignore
« Reply #5 on: June 12, 2017, 09:44:43 PM »

Konrad,

   Good Point on the video.  Sounds like If you found a stock 262 then getting a video would be hard because the stock one won't have the same flight time any way.  Or more likely people would think yours is stock then be sorely disappointed with the performance of their model. 

    I know you keep your model in Co but i'd love to see it at my field.  The EDF guys would go bonkers seeing the performance you describe. 

Hank
So others can benefit, is why I try to post in excruciating detail what I've done converting a sow's ear into a silk purse. I know it takes some gold but if you had made the mistake and purchased a Freewing product you might as well add a few more dollars. With some attention to detail you actually get a fun flying model with low emotional investment.  After all that is what foam (check book) modeling is all about.
Logged

Cut it twice and it's still too short!
Bill G
Silver Member
****

Kudos: 2
Offline Offline

United States United States

Posts: 169




Ignore
« Reply #6 on: June 13, 2017, 12:13:11 PM »


As to performance I know "pic's or it didn't happen" is the web motto. Or in modern times the ignorant masses want to see video. To show how much different the performance is I'd actually need to fly two models head to head in the same video otherwise perspective is lost.

All the best,
Konrad
That is very true.  We have the internet expert crowd to thank for that.  Those types where it quickly becomes obvious that they likely haven't actually built or possibly even flown anything...so we now need to post documented results.  Recently I got called on one of these situations, posted a video in a view days, and then the kid (0 build threads or videos) criticized the video.
Logged
steveair2
Silver Member
****

Kudos: 4
Offline Offline

United States United States

Posts: 185



Ignore
« Reply #7 on: June 13, 2017, 12:51:45 PM »

Nice work Konrad.  I've been salivating over the Freewing Mig 15.  Maybe one day I can spend the money on one.
Logged
Konrad
Platinum Member
******

Kudos: 27
Offline Offline

United States United States

Posts: 1,602


Topic starter
Measure twice cut once



Ignore
« Reply #8 on: June 13, 2017, 09:58:44 PM »

Thank you Steve.

Not knowing what you want from a model. But I would look at an Alfa Mig 15. I had one and can tell you it was the best flying foam EDF model I've flown. At first I thought it is on the small side with the 60mm fan unit. But I had way over 1.3:1 thrust even at 6K feet (I was using a Don's Wicked motor). I also felt that the fuse was very near scale in shape.
https://www.alfamodel.cz/index.php?_RQwhat=product&_RQid=_1011&_RQid_2=11011

The Freewing is a bit porky in that it is made of EPO foam and it flies as such even with the 64mm fan. It also looks to be to be a bit fished mouthed in the inlet area.
http://www.rc-castle.com/index.php?route=product/product&product_id=1030&search=mig+15

The 80mm Mig 21 is Freewing's best offering to date in a small scale EDF jet.
http://www.rc-castle.com/index.php?route=product/product&product_id=6238&search=Mig+21
Logged

Cut it twice and it's still too short!
steveair2
Silver Member
****

Kudos: 4
Offline Offline

United States United States

Posts: 185



Ignore
« Reply #9 on: June 14, 2017, 02:15:02 AM »

Konrad, thanks much for the information.  Funny,  I meant to type Mig 21 not Mig 15.   Have you flown the 21?  I sure do think it's a neat plane.
I asked for a Mig 21 for Christmas but got a quad copter.  Sucked hiding piss off emotions.  I don't like quad copters at all.
This year I'll ask for a ten dollar Volare kit.  Thanks for sharing your experience and mods on your Freewing model.

Logged
Konrad
Platinum Member
******

Kudos: 27
Offline Offline

United States United States

Posts: 1,602


Topic starter
Measure twice cut once



Ignore
« Reply #10 on: June 14, 2017, 09:17:26 AM »

Yes, I've flown the Freewing 80mm Mig 21 with 1800Kv outrunner motor. No, I haven't owned one and am not likely too.

Being as I didn't set up the Mig 21 that I flew I can't honestly give an assessment as to the kit or even its flying qualities. I will say that the model I flew was not set up to my liking. But as with all Freewing products I felt that with some attention to detail it could fly much better.

Of all the Freewing 80mm jets I like flying the Mirage 2000C-5 the best. It has the most wing area of the jets I've flown.  The F-86 was ok but for a swept wing model it was a distant second to the Me 262. Now I have not flown the A-6.

All the best,
Konrad
Logged

Cut it twice and it's still too short!
Konrad
Platinum Member
******

Kudos: 27
Offline Offline

United States United States

Posts: 1,602


Topic starter
Measure twice cut once



Ignore
« Reply #11 on: October 01, 2017, 10:47:04 PM »

I knew I was just kidding myself when my artsy sister was laughing at me for the huge tip clearance! Changed the 70mm Freewing housing to the WeMoTec  that was designed for the 68mm Evo rotor. I had to add filler to the OD of the WeMoTec housing to get it to seal in the duct.

I’m ashamed to say it but my sister was right the huge tip clearance was a joke. With the much tighter tip clearance the Me 262 has much much better performance. Don’t do as I did and kid yourself that the fundamentals don’t apply to you.

All the best,
Konrad
Attached files Thumbnail(s):
Re: Freewing Me 262 (upgrades and whatever)
Logged

Cut it twice and it's still too short!
Pages: [1]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!