-Correx Mig-7 Scratch build- - Page 222 - RC Groups
Thread Tools
Mar 20, 2017, 12:53 PM
.....till the wind drops.
Sean Oelofse's Avatar
I came across these pics from our air show back in 2015 taken by Sakkie . Don't think I posted them.... ooooops if I did!
It is Johanns E-Mig piggybacking an Alula. Very crude engineering .... but worked very well!! .... light ply frame locating off the wing elastic dowels ..... with a HXT900 servo secured to the frame and plugged into a spare channel on the receiver. Elastic band also secured to the frame goes over the nose of the Alula and onto the servo horn. When the switch is thrown to release, the elastic slides off the servo horn and the Alula jettisons.
The E-Mig has oodles of power so it can handle the extra weight without a problem. The small finger on top of the frame holds the LE of the Alula down on launching because the prop wash tends to unseat it.

Anybody else made a similar jig?







(Files are a tad large .... so you can zoom in!)
Sign up now
to remove ads between posts
Mar 20, 2017, 01:07 PM
Building with TLAR precision
Zenmaniac's Avatar
Quote:
Originally Posted by Sean Oelofse
It is Johanns E-Mig
Who?

-= Dave
Mar 20, 2017, 01:15 PM
.....till the wind drops.
Sean Oelofse's Avatar
I've forgotten his surname! ..... wait..... let me ask Google!
Mar 27, 2017, 11:05 PM
Registered User
Fune's Avatar
I have some questions, yesterday I printed full scale the plan .

1-Which would be the best position for the servos of the fuselage, I see in the thread, the servo of the elevator in the back for example, I do not know if the rudder would also be better too.

2-In the wings you could place separate micro servo for example HS55 or better one standard servo in the center wing.

3-And with the construction like here in my country I can only get the 4mm coroplast, I do not know if it's better to make them in one piece the wing with aileron and not to make a separate piece with the wing., Because I would think that the exit edge would be very thick would be 12 mm, and would normally be 7mm (down and top 2mm wing, 3mm aileron)

4-I see two wing dihedral braces Sport and Original, I like used for slope what I used ?

Thanks,
Fune
Mar 27, 2017, 11:31 PM
Slope-a-Dope
Steve 0's Avatar
Fune, hear are some answers on how I built my Mig.

1. First, no rudder, no rudder servo. I have a static vertical fin. Elevator servo is in the fuse at the wing center.

2. In mine, only one standard servo for the ailerons. I have seen the two servo wing set up. Either with work fine.

3. I would go with your plan on no extra piece for the aileron. Using 4mm coroplast, you need to save weight especially aft of the CG. So maybe even light balsa or foam ailerons is better? Just an idea.

4. For dihedral? I checked mine. It is 3" ...so sport dihedral spar setting. Still pretty stable. Rolls well and flies inverted easily.


These are very durable planes. Yours will need more wind lift being made out of 4mm. Mine is 2 & 3 mm.

Hope this helps.

Steve
Last edited by Steve 0; Mar 28, 2017 at 12:03 PM.
Mar 28, 2017, 12:09 AM
Professional amature
Quote:
Originally Posted by Fune
I have some questions, yesterday I printed full scale the plan .

1-Which would be the best position for the servos of the fuselage, I see in the thread, the servo of the elevator in the back for example, I do not know if the rudder would also be better too.

2-In the wings you could place separate micro servo for example HS55 or better one standard servo in the center wing.

3-And with the construction like here in my country I can only get the 4mm coroplast, I do not know if it's better to make them in one piece the wing with aileron and not to make a separate piece with the wing., Because I would think that the exit edge would be very thick would be 12 mm, and would normally be 7mm (down and top 2mm wing, 3mm aileron)

4-I see two wing dihedral braces Sport and Original, I like used for slope what I used ?

Thanks,
Fune
Here are some photos of how I approached servos. I did not add a servo for the rudder. If you can use eBay I recommend the EMAX ES08MAII. These are durable and cheap! My elevator control rod is inside one of the flute/channels and has worked out nicely. The wing servos as shown actuate torque rod control rods. These are more work to build, but it make the plane prettier!!

I improvised a wing spar made of a carbon arrows, and epoxy. The dihedral brace (sport vs original) is not that critical. The original will be more self correcting and relaxed to fly.

4mm will be heavy but good for higher winds. The inner exit wing surfaces could be tapered to thin the exit edge (see my wing photos). Perhaps construct the ailerons from a single thickness of 4mm.

Ed
Mar 28, 2017, 03:27 PM
Registered User
Extreme Sports's Avatar
Quote:
Originally Posted by Fune
I have some questions, yesterday I printed full scale the plan .

1-Which would be the best position for the servos of the fuselage, I see in the thread, the servo of the elevator in the back for example, I do not know if the rudder would also be better too.

2-In the wings you could place separate micro servo for example HS55 or better one standard servo in the center wing.

3-And with the construction like here in my country I can only get the 4mm coroplast, I do not know if it's better to make them in one piece the wing with aileron and not to make a separate piece with the wing., Because I would think that the exit edge would be very thick would be 12 mm, and would normally be 7mm (down and top 2mm wing, 3mm aileron)

4-I see two wing dihedral braces Sport and Original, I like used for slope what I used ?

Thanks,
Fune
Has anyone built a wing from 4mm corro? I'd be a bit concerned that it will be so rigid that it won't bend to the airfoil shape and getting the TE to stay glued may be a struggle. Please report back how it works.

If I had to use 4mm, I'd experiment making the aileron as an extension of the top or bottom skin. That way the joint would only be 8mm thick, and the 'step' only 4mm. This will mean cutting the hinge line ACROSS rather than along the flutes. But its is easy enough to do (see attached pic). Normally an Aileron with the flutes running chordwise like this would be too flexible, but I anticipate that 4mm correx will be rigid enough for this not to be a concern.
Mar 28, 2017, 07:47 PM
Slope-a-Dope
Steve 0's Avatar
The 4mm thickness can be turned into an asset....scale up!

Make the airframe at 150 to 175% larger and you have a bigger flies better Mig with similar wing loading to a standard sized plane.

Mig-a- saurus Rex.

Giga- Mig.

Mig-zilla. Yeah!
Mar 29, 2017, 02:38 AM
Warbirds Lover
Dreamcatcher's Avatar
If you have enough space to carry and store her, that's a good idea !
Mar 29, 2017, 10:35 PM
Registered User
Fune's Avatar
Thanks guys for all the tips.
Fune
Jun 08, 2017, 04:48 AM
.....till the wind drops.
Sean Oelofse's Avatar
I'm waiting for the wind to swing direction! ..... about twenty degrees will do just fine! ....... then I could tie my car battery to my Mig!


Check Maitlands!!!!
Jun 10, 2017, 09:17 AM
Registered User
SwaFly's Avatar
Sean, good to see the tread isn't dead!
How do you keep your feet on the ground in that wind?
Jun 10, 2017, 09:49 AM
.....till the wind drops.
Sean Oelofse's Avatar
We still here SwaFly!
Didn't get to fly Thursday .... the wind didn't turn!
But did fly Sunday ......epic conditions!

Dave made a video ...... link to follow soon!
Jun 10, 2017, 11:04 AM
Reap the wild wind
headlessagain's Avatar
Looks like Dave might be a Van Halen fan That's what they call "big air"conditions I think the highest wind speeds I've flown in were 50 mph and that was a DF Weasel!
Jun 13, 2017, 07:21 AM
Reap the wild wind
headlessagain's Avatar

Maiden flight


A big thank you to BigPhil1967 for building the Mig-7 for me. I must also apologise for the delay in getting this airbourne. I did amend Phil's build by moving the elevator servo from the tail to the fuselage and running the control rod through the flutes as some others have done.
We chose to launch it from the backside of the slope figuring that the long grasss would cushion any arrival. We needn't have worried as it climbed out and cleared the slope edge with ease. In fact if was nearly climbing as well as my friends Chris Foss Middle Phase glider. Then again average 30 mph winds helped
What started out as just a quick test flight turned into a 30 min flight as I was having so much fun. I later solo hand launched without problem and passed the tx to Doug to have a go on the sticks. He was very impressed and, being a skilled balsa basher, would have no problems in knocking one up
Here's the edited video. Sorry it's a bit longer than my usual ones but found it really difficult to reduce it down too much.
Time to add some colour. Packing tape might be a bit opaque for the wings so I'll see if my local vinyl shop have any off cuts.
Correx Mig-7 PSS maiden flight (4 min 39 sec)

Andy


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log first scratch-build! :D ClippedWings78 Foamies (Scratchbuilt) 7 Nov 01, 2010 07:45 PM
Build Log MiG-15 in 1/10th scale for PSS: A Scratch-Build John Rood Slope 4 Sep 17, 2010 08:41 PM