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Old May 01, 2007, 12:43 AM
AMA 667982 KG7NKY
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Tucson, AZ, USA
Joined Sep 2000
1,974 Posts
Quote:
Originally Posted by mecevans
how is everyone elses mfx holding up? mine starting to get pretty beat up

Good to hear about your trany battery. I'm very conservative when flying mine. When I try to hover I'm usually around 100'+ . Only had two mishaps and both were my fault. First, I forgot to strap the battery down and it slide to the trailing edge of the wing. Talk about learning to fly a tail heavy plane I was able to get it back and on the ground safely. Next day I was showing off and lost it on landing and cracked the right wing. No big deal as repairs were rather easy and I just resealed the covering.
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Old May 01, 2007, 03:51 AM
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Joined Jan 2007
45 Posts
Hi guys,

Thought I'd join in the conversation and ask a few questions being fairly new to the whole electric flying game.

I've had 6 flights with my E-Flite MFX now and I'm still getting used to flying with Dual Rates and Expo on my Spektrum DX6 (had a cheap 4 channel radio before this which I used for flying foam park planes).

I've tried doing the blender but I can't get it to flat spin on its back - I think the CG is too far forward. Where do you 3D Pros set your CG "sweet spot" for doing 3D tricks like Blenders; Hovers; etc?

Also, what are your throw measurements on the Rudder; Ailerons; and Elevator? I can't get huge throw from my elevator (I think my servo is straining - maybe I should replace it with a high torque Naro servo?)

Lastly, how much Expo do you set for your High Rates on your Rudder; Ailerons; and Elevator?

Any help/advice you can give me would be fantastic so I can do some cool 3D tricks like you guys do .

Cheers,

FOX1
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Old May 01, 2007, 05:42 AM
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Alpharetta, GA
Joined Jun 2006
454 Posts
You'll need to have the CG back, but on this plane, shifting the battery even 1/2 an inch can make a BIG difference. Shift it back slowly until it starts to do 3D better. Also, for good blenders, flat spins, etc... you'll need to extend the rudder on this plane, it just doesn't have enough. There are a couple of discussions, pictures and stuff earlier in this thread... most people are just using foam taped to the side of the rudder. Good Luck!
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Old May 01, 2007, 02:13 PM
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Quote:
Originally Posted by reyn3545
You'll need to have the CG back, but on this plane, shifting the battery even 1/2 an inch can make a BIG difference. Shift it back slowly until it starts to do 3D better. Also, for good blenders, flat spins, etc... you'll need to extend the rudder on this plane, it just doesn't have enough. There are a couple of discussions, pictures and stuff earlier in this thread... most people are just using foam taped to the side of the rudder. Good Luck!
Hi reyn3545,

thanks heaps for the info - much appreciated. I'll move the CG back slowly and test the 3D. Can you tell me what amount of throw you have on your elevator and rudder each way (I've got the throws from the manual on mine but I think I need more). Also, as I haven't used Expo before so I'm not sure how much to be using

Thanks for your help

Cheers,

FOX1
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Old May 01, 2007, 04:10 PM
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Newbury Park, California
Joined Apr 2002
651 Posts
FOX1:

The easiest way to get the CG close is to trim for level flight at the throttle setting/speed you normally fly. Then, fly inverted and see how much down elevator is required to hold that same level flight. Move the battery until very little down is needed to hold level inverted flight. This will get your model very close to neutral longitudinal stability and make it much more responsive to control input.

You will need to retrim each time you move the battery. You'll probably need to reduce total elevator travel and perhaps increase expo as well as you move the CG aft.

I have my MFX CG far enough back that almost no down elevator is required to hold level inverted flight. The plane is very responsive and can do anything it is supposed to do. However, it is not particulary groovy, has to be flown all the time and is very floaty on landing. When I wish to have a more relaxing flight, I move the battery forward a quarter-inch to increase stability and reduce control sensitivity.

Joe

BTW: With an aft CG, it'll be much less likely to stall at low speed and will land slower too.
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Old May 01, 2007, 07:16 PM
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Quote:
Originally Posted by Joe Minton
FOX1:

The easiest way to get the CG close is to trim for level flight at the throttle setting/speed you normally fly. Then, fly inverted and see how much down elevator is required to hold that same level flight. Move the battery until very little down is needed to hold level inverted flight. This will get your model very close to neutral longitudinal stability and make it much more responsive to control input.

You will need to retrim each time you move the battery. You'll probably need to reduce total elevator travel and perhaps increase expo as well as you move the CG aft.

I have my MFX CG far enough back that almost no down elevator is required to hold level inverted flight. The plane is very responsive and can do anything it is supposed to do. However, it is not particulary groovy, has to be flown all the time and is very floaty on landing. When I wish to have a more relaxing flight, I move the battery forward a quarter-inch to increase stability and reduce control sensitivity.

Joe

BTW: With an aft CG, it'll be much less likely to stall at low speed and will land slower too.

Hi JOE,

many thanks for the great advice!!

This is exactly the kind of info I need. Here I was thinking I had to MAX the travels on all the surfaces to get good 3D, but that's obviously not really necessary by the sounds of things.

I was a little weary of moving CG too far back because of concerns about tip stalls and issues at low speed, but again it sounds like this is not really an issue. A shorter landing distance would also suit me as sometimes I fly at a small sized park and really have to use up most of it. So with slower landing speeds, things should be a little less stressful

Many thanks again for your advice - it's much appreciated

Cheers,

FOX1.
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Old May 01, 2007, 08:25 PM
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Newbury Park, California
Joined Apr 2002
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You're welcome FOX1.

It may sound contrary to much you may have heard, but -- an aft CG is less likely to tip stall, will land slower and remain more contollable at low speed. Just remember to reduce total elevator travel and add exponential as you move the CG back. Take your time, make small changes and retrim as needed with each change.

I predict that, as you move the CG back, you'll find that your MFX will seem more stable, be much more responsive and it'll be easier to fly as well.

Great plane, great fun -- I love it!

Joe
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Old May 02, 2007, 12:11 AM
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Quote:
Originally Posted by Joe Minton
You're welcome FOX1.

It may sound contrary to much you may have heard, but -- an aft CG is less likely to tip stall, will land slower and remain more contollable at low speed. Just remember to reduce total elevator travel and add exponential as you move the CG back. Take your time, make small changes and retrim as needed with each change.

I predict that, as you move the CG back, you'll find that your MFX will seem more stable, be much more responsive and it'll be seasier to fly as well.

Great plane, great fun -- I love it!

Joe

Hi JOE,

thanks for the further explanation. It'll be great to get slower landings and more resposiveness at low speed - I'll make small changes to CG and trim after each, as per your advice .

Can't wait to test out these changes - pity it's been raining here for 2 days

It is an AWESOME plane. I wonder what the new E-Flite Extra will be like?

Cheers,

FOX1
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Old May 02, 2007, 11:21 AM
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Tucson, AZ, USA
Joined Sep 2000
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OK guys, Solved that battery problem I was having earlier this week by finally reading the instructions. No I mean really reading the instruction and finally finding the information I needed.

Anyway 4 flights yesterday and 5 more today ah! I'm jacked on this plane. What a treat to fly as it is so predictable in its habits. What I really find funny about electrics is that by now most of my gassers would be soaked in oil with glue joints getting ready to fail. This plane looks almost like it came out of the box yesterday and I've been flying it for almost six months now. Only wish we had this kind of quality 25 years ago. I can just see some of Ken Willards designs toting outrunners and blazing up the sky. RIP Ken, you influenced thousands of modelers over the years.
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Old May 02, 2007, 01:18 PM
Mechanical Eng. Student
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Tennessee
Joined Jun 2002
330 Posts
I had quick question for some you X flyers; I have been flying mine with the 480 for about six months now. I have been using the TP 2070's and the FP 2170's (3s 25C discharge) and the 12x6E APC Prop, Jeti 40 Opto and a Seperate BEC. I was wondering if some of you guys may have some experience with some more powerful motors over the 480. I've heard talk about some of the AXI's on the X's but I was curiours if any has some head to head data. Just a tad bit more pull out would be wonderful. Thanks in advance.

Addison
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Old May 02, 2007, 01:32 PM
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Newbury Park, California
Joined Apr 2002
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hoverkid87:

If you have a copy of Motocalc, take a look at the 480's performance with a 4S battery & APC 9x6 or 9x7.5 props. The performance increase is simply huge! The 480 & 4S combination clearly out-performs the E-Flite Park 10 with a 3S battery.

Joe
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Old May 02, 2007, 04:27 PM
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Newmarket,Ontario, Canada
Joined Dec 2002
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i have a similar size/weight plane(SA edge 35oz) with a power10 on it and have flown my friends mini funtana X with the 480/1020 set up. the power 10 has a fair bit more punch i think it would be the next step from the 480/1020. only "down" is flight times drop off to a little compaired to the 14min i get around 10. with the same prop it works out to about 1000 more rpm on the 12x6E prop! ps this is real world data not just motocalc numbers
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Old May 02, 2007, 04:50 PM
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Tennessee
Joined Jun 2002
330 Posts
I will try the 4s. I have access some packs and we'll see how she fairs.

Thanks a ton!
Addison
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Old May 02, 2007, 06:26 PM
Balsa to the Wall
Deep in the East Texas Piney Woods
Joined Dec 2001
4,553 Posts
Fox1
This may be old news, but if you are new to exponential, you want to dial in negative expo to make it less responsive around the middle of the stick and more responsive as you approach the end of stick travel.


Chuck
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Old May 02, 2007, 07:41 PM
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Quote:
Originally Posted by Chuck
Fox1
This may be old news, but if you are new to exponential, you want to dial in negative expo to make it less responsive around the middle of the stick and more responsive as you approach the end of stick travel.


Chuck
Hi Chuck,

thanks for the input - I've managed to get this bit sorted.

Many thanks anyway for the "Heads Up"

Cheers,

FOX1
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