Thread Tools
Jul 20, 2011, 06:24 AM
Team30 Micro EDF
NitroCharged's Avatar
I don't have pitch issues - sounds like you guys need to better balance the Mig.
Sign up now
to remove ads between posts
Jul 20, 2011, 06:40 AM
Life begins at transition
I cut a V out of the bottom seam. It would appear to move the exhaust upwards, which would really excaserbate the problem. It's quite noticable, but I've gotten used to it. 1/2 throttle is trimmed, idle needs a lot of back schtick, max needs a lot of forward. Not ideal, but it flies!

NC - Your thrust tube I think bypasses the problem in the foam exhaust. My gut feeling (and I didn't check when I had the fuse is pieces!) is the bottom part of the fuselage tapers up at the exhaust, whereas the top stays pretty much straight. That'd act a bit like a thrust vectoring nozzle, permanantly pushing the tail down.
Your tube would be a straight line all the way back - no angles, no problems.

Like always, jets need tubes. Truth be told, I completely forgot when I was re-assembling! Otherwise, I'd spend the 5 min, get better thrust, and no pitching issues
Jul 20, 2011, 08:28 AM
Registered User
mihah's Avatar
I have thrust tube installed on the bottom of the exit. Just transparent mylar foil which goes from 110 mm to 98 mm circumference and ends at the exit. I have just taped the tube to the edf and it sits quite tight.

I made THR -> ELEV mix about 11 % in total (5-6 % in each direction from the center). If I fly smootlhly there is hardly any pitch change noticable, even with throttle off.

I really like this little plane a lot! :-)
Last edited by mihah; Jul 20, 2011 at 08:45 AM.
Jul 20, 2011, 08:34 AM
Registered User
flypaper 2's Avatar
I would agree with Nitro that it's a balance problem. Sounds nose heavy if you need a lot of up elevator to keep the nose up with power off. With a fast flat glide, the elevator should be level or neutral.

Gord.
Jul 20, 2011, 09:13 AM
Gravity is a harsh mistress.
Tim Wolff's Avatar
Quote:
Originally Posted by flypaper 2
I would agree with Nitro that it's a balance problem. Sounds nose heavy if you need a lot of up elevator to keep the nose up with power off. With a fast flat glide, the elevator should be level or neutral.

Gord.
Thanks for the tips on the CG. I have an F/A-18 that pitches up like crazy with throttle. I'll move the CG back and see how it does.
Jul 20, 2011, 09:56 AM
Registered User
...I didnt read far enough.. (edit)
Jul 20, 2011, 10:41 AM
Registered User
bluemeane's Avatar
Quote:
Originally Posted by SonicRaT
Read the thread from start to finish, and had to jump on board! Using the Buddy Code's it all came out surprisingly cheap! After going through the thread here's the various odds and ends I settled on:

F86 ARF (just can't get into the mig lines...)
Orange 4ch receiver
Turnigy Plush 10A ESC
Turnigy NT 460mAh 3S
HK 2.5g Micro servo's
.5 Carbon rod

Should make for a fun addition to my rather tiny hangar, and certainly will keep me busy while I search for various parts to restore my Sapac F-22 to flight condition!
What is a "buddy code"? And how can I get one(some)?? lol


Edit: So i found out what they are... Do you have a buddy code for your order?? I'd love one.
Last edited by bluemeane; Jul 20, 2011 at 10:47 AM.
Jul 20, 2011, 06:00 PM
Registered User
I just got the red mig at my office today. I have some 2c nano's on the way. What is the best way to get a DSM receiver in there? Solder on new plugs? What RX have people been using? if soldering on new plugs, is there a handy source for pigtails?

Thanks,
scott.
Jul 20, 2011, 06:43 PM
Life begins at transition
FP2: Yes, the CoG is too far forward, as I've already alluded to (excessive stability), but if you move it too much further aft, the 'death spiral' becomes even more prevelant.

Also, the pitching happens on application of throttle, not just with changes in speed.

As Nitro said, if you stick a thrust tube in it, the problem goes away. He's using the same CoG (within 1mm give or take), but doesn't have the thrust vectoring.

It won't take long to fix, but does involve slicing the fuse in half again. I think I'll wait 'till I'm replacing the power system and do it then, as it's flyable and enjoyable as is, just not perfect.

Guppy - I left the pins on my Rx, but took the plastic keepers off the micro servo leads. The metal sockets will still fit onto the standard sized pins. I was thinking of removing the pins and soldering everything, but when I found they fit with very minimal modification, I couldn't help but be lazy!
Jul 20, 2011, 06:59 PM
ancora imparo
jj604's Avatar
Just a quick question. Do you have to slice the fus to fit a tube? My Mig has a 36.8mm exit hole which is identical to the OD of the fan housing. If I recall Nitro said he was using a 34mm exit tube. Why can't you just make a 36.8mm OD at the front, 34mm ID at the back thrust tube and stuff it up the through the exit hole and glue it on? It would just fit through without any mods to the plane.
Quote:
Originally Posted by Odysis
As Nitro said, if you stick a thrust tube in it, the problem goes away. He's using the same CoG (within 1mm give or take), but doesn't have the thrust vectoring.

It won't take long to fix, but does involve slicing the fuse in half again.
Jul 20, 2011, 07:15 PM
Not enough hours in the day
Slaanesh's Avatar
Quote:
Originally Posted by jj604
Just a quick question. Do you have to slice the fus to fit a tube? My Mig has a 36.8mm exit hole which is identical to the OD of the fan housing. If I recall Nitro said he was using a 34mm exit tube. Why can't you just make a 36.8mm OD at the front, 34mm ID at the back thrust tube and stuff it up the through the exit hole and glue it on? It would just fit through without any mods to the plane.
I think the only advantage of the slice is that it's easier to fit at the cost of making a slice.

I would go with the method you've outlined despite the extra fiddling about.

I did the same thing to another EDF I built - made the fuse first then fit the thrust tube.
My trial fit became the real fit as it was so awkward and fiddly to do! From then on I vowed I would always make and fit the tube before completing the fuselage, if possible.

Sometimes I wish I had a third hand - would be extremely handy for modelling!

By the way John, where are you flying your little Mig-15? Local parks? Or SEMAC?
Jul 20, 2011, 07:27 PM
Life begins at transition
NC made his tube, and didn't mod the airframe.
For me, it was a quick, 2 min job to shrink the tail down a bit, whereas splitting the fuse takes a while. I've only tried to fit a thrust tube after fan installation once. Never again! So fiddly, as Slaanesh said, not worth it in my book.

34mm still seems excessive for a 35mm fan. But then again, NC may not be using the stock fan...
Jul 20, 2011, 07:31 PM
ancora imparo
jj604's Avatar
I just gave it a go at the local park. Nearly got eaten by a big white dog when it landed! Since it remains undamaged , I put it back in the hanger for now - other projects to do.
Quote:
Originally Posted by Slaanesh
By the way John, where are you flying your little Mig-15? Local parks? Or SEMAC?
Jul 20, 2011, 07:47 PM
Life begins at transition
Just got back from another couple of flights in my 'front yard'

FP - I checked it's glide. I cut the throttle up high, nosed over to about 45* nose down. As is picks up speed, it gently pulls up, but not more than maybe 10-15* in the height I gave it. When you punch the throttle, it goes to about 30* nose up!

The more I think about it, the more I should just bite the bullet and fix it
Jul 20, 2011, 08:57 PM
I don't want to land yet!
Ody, I made my thrust tube after gluing the fuse together.. Just tape the exit end and shove it in, then you can tape it to the fan, not ideal I know but it works fine. You can then put more tape inside from the back with a stick, doesn't need much to hold it...


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Mini Mig-15 EDF from Hobby King Dreamcatcher Foamy EDFs 6 Jan 16, 2012 09:58 AM
New Product JPower/Banana Hobby 40mm Foam Mig-15 and F-86 ducted fan Mikey 68 Micro EDF Jets and Power Systems 557 Aug 18, 2011 05:01 PM
Build Log Hobby King Micro A-6 & F-86 Jets tallflyer Foamy EDFs 4 Jun 04, 2011 02:05 PM
New Product J-Power 30mm EDF Jets (F-86 & Mig-15) xplaneguy Foamy EDFs 1 Jan 16, 2011 05:59 AM
Park/indoor EDF F-86 and MiG-15 production news! Thomas B Parkflyers 8 Feb 06, 2002 06:30 PM