RCP Mig29 V4 NAMCV2 and V3 flyoff

Hi everyone -

I was blessed with another calm, dry late fall day today, so a great opportunity to keep dialing in and fine tuning my new RCP Mig29 V4 NAMCV3 (which is the white plane on the right which I will call the V3 for the rest of this post) and do a flyoff with it and my Mig29 NAMCV2 (which is the blue camo plane on the left which I will call the V2 for the rest of this post).

These two planes are much more alike than the V3 and the stock Mig29 V4 I flew when I maidened the V3.  The rudders, ailerons and elevons are essentially the same size, the biggest difference being length and motor position which then affect several other portions of the flight envelope.

This was an excellent session of testing as it showed me how having simple physics working in my favor with respect to how the weight is centred on the V3 combined with how the CG (center of gravity), CT (center of thrust, referring to where the motor is located in the plane), CM (center of mass or where the bulk of the weight is located) being moved around by my modifications affected the plane's performance.  I am also sure that the CL (center of lift) has been moved on the V3 as well, but I'm not sure how I could test for that.  The other three, CG, CT and CM I can measure which I will do and discuss later in this post.

I also did a little research to reassure myself where a plane rotates and with a simple diagram and a little help from my friends at NASA ;)  relearned that an aircraft's point of rotation for all three axes is the CG.  http://www.grc.nasa.gov/WWW/k-12/airplane/rotations.html  I think this link was designed for kids, so it is barely within my grasp of understanding... ;)

Today was again a calm day, so still no real assessment on how the V3 handles the wind, that testing will have to wait for another day.  In calm conditions, both planes I would say are equally stable at middle to high speeds, there is a difference however at lower speed which I will discuss later.

Turns and general handling

The V3 requires about 10% less control input to perform a turn of the same rate/radius as the V2.  This is also considering that I have 10% less throw on the elevator input on the V3 than I do on the V2.  Aileron throws and expo are the same on both planes.  Rudder throw is the same on both planes, but to tame down the rudder responsiveness on the V3, I increased the rudder expo by 10% over the V2.  Both planes really carve through turns, track exceptionally well, but if I had to give a slight nod it would be to the V3.  Because of how it is better balanced WRT weight distribution, it just feels smoother and tighter with no wasted movement or loss of energy at all in turns.

Loops and pitch maneuvers

The V3 is more responsive and smoother through loops and other pitch maneuvers.

Rolls

As I said in my post flight, the V3 rolls like there is a rod right down the center of the plane that it rotates around.  Because the weight on the V2 is spread over a much larger area, sometimes in rolls it will twirl slightly like a drum majorette would twirl a baton.  In other words, the nose does not stay as level throughout the roll on the V2 as it does on the V3.

Yaw

The V3 is much more responsive in the yaw, as mentioned I had to down tune the expo a bit to keep from getting too aggressive in the yaw in high alpha and moves like a stall turn.

Slow speed and high alpha

This is where the V3 really sets itself apart from the V2.  In level slow flight with the throttle at about 35-40%, the V2 is very stable, but still feels like it is on a bit of a razor's edge from a standpoint of control and stability.  The V3 actually felt today a lot like my stock RCP F18 V3 at slow speed, almost like it had some sort of self correcting mechanism as it flew along, it felt noticeably more solid.  In high alpha, both require about the same amount of power, the spoilerons on both are identical at 5/8" travel, but to hold the nose at the same AOA (angle of attack) for both, the V3 needs about 10% less up elevator.  Because it rotates so well in the yaw axis, about 10% less rudder input is needed to bring the nose around in high alpha as well.

Before going any further, I don't want it to sound like every new Mig I build is amazing and all other Migs I built before that are no good, but it is a logical progression as Stephan and I think, design, test and validate each new sets of mods.  As I have mentioned before, this was definitely the most ambitious set of mods attempted thus far as a lot of things got moved around as a result of shortening the plane and moving the motor forward.

So of course, I had to get out the ruler (it never lies... :) ) and my dollar store calculator and put some numbers to what I was seeing and feeling at the field today.

During the first couple flights with each plane, I double checked that all my control surfaces were still dead center at zero trim and rechecked the CG on both.  The CG on the V2 is now 1" ahead of stock and the CG on the V3 is about 1/8" ahead of stock.

V2

Wingspan - 27"
Length - 40"
Distance of CG from nose - 20.5"
Nose to motor mount - 24.75"
From front of battery to rear of motor when balanced on CG - 14.75"
Distance from the CG to back of battery when balanced - 3.75"
Distance between CT (back of motor mount) and CG - 4.5"

V3

Wingspan - 27.5"
Length - 39"
Distance of CG from nose - 21.25"
Nose to motor mount 23.75"
From front of battery to rear of motor when balanced on CG - 10.75"
Distance from CG to back of battery when balanced - 1"
Distance between CT (back of motor mount) and CG - 3.25"

So when I look at these numbers, I admit I have always known that having as much weight as possible concentrated around the CG is better for overall balance and handling, but because of poor planning or the plane, I was never really able to get the weight concentrated as well as ended up on the V3.

So let's look at the weight of the planes.  The V2 is a bit lighter at 20.9 oz, the V3 is 21.5 oz (even though not painted it has much more carbon reinforcement and 10 gr extra in servo weight).

Total weight of battery, Rx, ESC, motor and servos for the V2 - 13.2 oz.  Same combination for the V3 - 13.3 oz.  Because the battery is the heaviest part of this equation, the battery for each weighs 6.9 oz, over half the total weight of the electronics gear.  This will become important again later on.

So the gear on the V2 makes up 63% of the plane's total weight and is spread over 37% of the total length of the plane when balanced.

The gear on the V3 makes up 62% of the plane's total weight, but is spread over only 28% of the total length of the plane when balanced, so it is concentrated in a much smaller area.

A couple other measurements that become quite interesting is when I look at where the batteries, which make up 33% of the total weight on the V2 and 32% of the total weight on the V3 are located WRT to the CG on each plane.  On the V2, this weight starts 3.75" ahead of where the CG is on this plane.  On the V3, this weight starts only 1" ahead of the CG.

In my opinion, this alone easily explains some of the differences in both the yaw and pitch axis on these planes.  The controls have to work much harder to pull the nose up in the pitch or bring it through on the yaw axis as the weight on the "lever" is much further from center explaining why more control input is needed on the V2 in both the pitch and roll just to lift that heavier weight further from the rotation point.  This may also explain why the V3 is more solid in rolls as there isn't that big bunch of weight so far out ahead of CG as it rotates on the roll axis.

Since although I shortened the back end of the V3 by 1", I also moved the motor mount ahead by 1", so the distances between the prop and the elevons and rudders are the same on both planes.

So looking at where the motor and CT of thrust are now located on both these plane and how it affects the CG.

If we break the length of the planes into percentages, the motors are essentially in the same location with respect to total distance of the plane.

V2 - motor mount 24.75" from nose divided by total length of 40" = 62%

V3 - motor mount 23.75" from nose divided by total length of 39" = 61%

If we look at where the CG is located on each plane WRT to total length.

V2 - CG 20.5" from nose divided by 40" = 51%

V3 - CG 21.25" from nose divided by 39" = 54%.

So if we then look at a couple other numbers, the distance between the CT and CG on both planes, they are quite different, the CT and CG are significantly closer on the V3 than the V2 by 1.25".

So although the CG is closer to the very centre of the airplane on the V2 than the V3, the CT on the V3 is about 40% closer to the CG which I think helps make rotation in all axes more efficient and effective.  Also, by bringing the CT forward, it brings the CG back and when coupled with how much closer the main body of mass on the plane (the battery) is located to the CG, it makes sense that the airplane is not only better balanced, but rotates that much better as the CT, CG, CM (center of mass) and I assume CL are all much closer together.  Quoted from the link above

"In flight, any aircraft will rotate about its center of gravity, a point which is the average location of the mass of the aircraft."

I hope that I am following a logical path with this thinking, there is certainly some serious mojo going on there with these changes that were made, I'm sure all working together to make this plane better balanced, more responsive in all axes and overall more stable and self correcting.

Another fun and educating day at the field today for sure.  Amazing how a few manageable changes on a plane can make such significant differences in how they perform.  That and I just love how this V3 looks in the air, more compact, more solid and more scale looking and flying.  I am truly happy and satisfied how all these changes have worked out... :)

Next up will be to paint it, change the power system and then do some more testing with higher wing loading and speed... :)

Cheers,

Scott

RCP Mig29 V4 NAMCV3 mod pics/diagrams/info - updated 06 Nov 2014

Hi everyone -

I managed to get done what I hope will be a series of useful diagrams/pictures and supporting info on my latest Mig29 V4 NAMCV3 build.  It is an ambitious set of modifications, so the diagrams may seem a little busy and complicated at times, but I hope they are usable if you want to duplicate them.

Since one of my main goals in this project was to morph the Mig29 into a Mig35, I used this diagram of the Mig35 for reference for my wing and elevons since I had to free hand draw the curves somewhat.

I will start at the rear of the plane and move forward.  I drew my mods on a set of untiled plans from the print shop but they should work on tiled or untiled plans.  If you right click on any of the photos in this post, you can save them so that you can enlarge them at your convenience, or if you e-mail me at migsrus@outlook.com I can email them all to you.

Elevon/back plate mods

Unfortunately I am not that computer gifted, I tried to make a template that might be usable for you to print off and lay over the stock plans, but that did not work as well as I would have hoped... :/

Edit 01 November

I added this picture of a tracing of my NAMCV3 elevon mod that I scanned into my computer.  Perhaps if you are more technically gifted than I (which is very highly likely... :) ) you can make it work for you.  When re-sizing and printing the picture, it is important to ensure your hinge ling measures as close as possible to the 6 and 13/16" as shown in the picture.

This first picture shows in yellow the modified elevon, hopefully you can follow all the measurements and angles.  For the two corners at the tip of the elevon I hand drew in the curves using the diagram above as a reference.  What I might recommend is to print off the pages you need from the tiled plans, do the drawing on that, make yourself a template from some scrap foam or cardboard to ensure you have it shaped the way you like and then trace that on your final plans to ensure everything lines up OK.  This is an extra step, but will allow you to do what changes you need before cutting out your final parts for your build which should hopefully save you some foam and frustration... :/.

This second picture shows that I moved the tab on the side of the back plate back 1" since I am going to be moving the back part of the fuselage forward by 1" and I also like to move the back of the prop slot to the rear.  I didn't draw in how I like the rear of my prop slot to go, I'll leave that to you.  Mine is a pretty big hole in the middle of my plane, but when I put the NTM motor on my plane, the prop will be moving back about 5/8" from where it is with the Focal Price motor, so I wanted the extra room in my prop slot.

There is a lot going on on the whole rudder/vert stab/side fuselage/nacelles intake piece, this piece shown below.  It might be easiest to print off the tiled plans to do all your drawing and reconnecting before cutting the final pieces out.  I made a template out of scrap dollar store foam and then laid it over the plans before cutting out my final pieces.

I found it easier to do this whole piece in steps, starting with whatever vert stab/rudder mod you want to do.

Vertical stab/rudder

To accommodate the type of rudder style that I like and to make it look more "Mig35ish" which was my goal, I went with the same rudder and vertical stab setup I used on my Mig29 NAMCV2.  You can use whatever rudder size you like, but if you want it to look "Mig35ish", I would keep the outer dimensions and angles of the trailing edge of the rudder and the vertical stabilizer.  The black "squiggly" lines are of no use to the mods, just to divide the different mod areas up on my diagram to denote the different sections as there are essentially three mods on the same piece of this plane.  I found it easiest to do all this drawing first before moving onto the next step of shortening the rear fuselage.

Shortening rear fuselage

This is a pretty busy picture with lots going on, so I broke it down into three steps to hopefully make it easier to follow.

Step 1

Measure and cut out the area outlined in orange.  This needs to be taken out to accommodate moving the motor further forward by 1" and shortening the rear fuselage by 1".

Step 2

Measure and cut out the area outlined in yellow.  Do not cut out/off the area marked with the * as leaving that there will make it easier to line things up and tape them together in step 3.

Step 3

Line up and tape line A to line B, this will then shorten your rear fuselage by 1"

I didn't make this a step, but you will note at the bottom of the picture, you will need to move the tab on that inner part of the nacelle forward by 1/2".

Curved/"ski tip" front of intake mod

This is an optional mod depending on what you like, I found from my first 10 flights it makes landing much less abrupt as the front of the intake does not dig into the ground.  Once you measure out the angled parts as shown, you will want to move the leading edge of the middle part forward to ensure that it is long enough when you bend it forward to make the "ski tip".

Wing/aileron mod

I made these mods to give it the "Mig35ish" look.  If you look at the diagram at the very start of the post, you will note that the wing on the Mig35 is kind of "F15ish" where the wing is 90 degrees to the fuse for the first bit, then it angles back slightly and the tip is slightly curved.  The inside edge of the aileron starts 3/4" from the wing root to accommodate running the elevon pushrod on the outside of the fuselage.  You may have to kind of free hand the curved wing tip, I extended the tip out by 1/4" at the centre of the tip and then curved it gently back into the leading and trailing edges.  Again, you can use my drawing below or the Mig35 plan view above as a guideline.

KF Airfoil mod

I used KF4s (top and bottom) on my Mig29 which is what I would recommend for best speed and stability.  Because I altered the wing shape somewhat, I moved the trailing edge back to make it approximately 40% of the wing chord which I find works the best on the Mig.  How I did this was I extended the trailing edge back 7/16" at the root and 1/4" back at the tip.  You will also want to ensure you trace the curved portion and slightly extended wing tip on your new "Mig35ish" wing.  You can do this by laying the wing plate over the KF and then just trace it before you cut the KF out of the paper.  The drawing on the plans is quite confusing in my opinion.  Where it is labeled "KF4 airfoil (optional)" and "KF2 airfoil (optional)" should be reversed.  The large piece including the portion that covers the leading edge extension goes on the top (KF2).  Then if you use KF4, you cut out the smaller airfoil using the dashed line for reference.

What I like to do is make one of the KF2 airfoils, dry fit it, then use that as the template to make my second KF2 airfoil.  Once I am happy with those, I then cut along the dashed line, ensuring I continue the long dashed line all the way back to my new trailing edge, then use that as the template for my bottom (KF4) two airfoils.  Hope I haven't made this too confusing.  The important thing about KFs is to ensure the wingtips are uniform, therefore the trailing edges should be equal as well.

Motor mount mods

In order to move the motor 1" forward, you will need to move the front of the prop slot and motor mount area all forward by 1".  It might be hard to see as on the plans the dark line where they suggest the wing spar goes covers up where the new front of the prop slot will be, but hopefully you get the idea.  You will also note that I moved the two slots that accommodate the tabs from the inner part of nacelles 1/2" further forward so you have a good solid gluing area.  

Since the area then gets a bit tight for space to put in your carbon fibre wing spar, I ended up putting my spar across the two slots as you can see below.  I then had to cut little notches in the tabs that go into them, but it worked out well and there is no loss of structural integrity.

In the picture below, I show adding about 5mm to the top of what will be the back of the motor mount.  The reason being (I found this out the hard way... :/) is because you are shortening the back of the front fuselage, the angle is different so when you put the battery hatch door down, there is a pretty good gap between the hatch door and this piece where you would put your magnets to secure the door.  I ended up gluing a scrap piece of dollar store foam on the top of mine to make it all work, so I put this in as a mod so you can modify it before putting into the plane then if you find it too high, you can shave it down a bit.

Shortening front fuselage

Since you will be moving the motor mount forward by an inch, you need to shorten the front fuselage accordingly.  You can see how I moved everything (including the slots where the fuse slides onto the wing plate) by 1".  These are how the pieces are laid out on the untiled plans, you need to do that large fuselage piece as well as the top piece that is the top of the fuselage.

Nose former/bulkhead mod

Depending on how you lay out your components, you may or may not need to worry about this mod to have the extra room in the electronics bay, but if it means lightening the plane up a bit without compromising structural integrity, why not?  :)

So if you choose to do this mod, you will want to move the three slots that accept the tabs on the bulkhead forward by 1" as well as the rectangular air vent so that you have more room to apply Velcro.  I made what will be the side slots for the bulkhead a bit shorter so that I didn't have such a thin bit of foam between the bottom of that slot and the slot that accepts the tab from the front of the leading edge extension (LERX) of the wing plate.

Then I just measured and cut 1" off the back of the nose former piece.

Then I adjusted the tabs on the side of the bulkhead to ensure they fit properly into the new slots I made on the sides of the fuselage.

Edit 06 Nov 2014 - nose tip mod

I forgot to mention this when I wrote the original post and it is completely optional since I did it more for aesthetic reasons to make the canopy appear a bit more further forward and the front nose section a little shorter.  I actually made a mark 1/4" from the end of each "finger" on the nose and then as I cut it out I carefully cut in to that mark to make the nose section about 1/4" shorter once it was all glued together.  Again, purely aesthetic, not necessary unless you want that look as well.

So hopefully this has been somewhat useful to you, some of what I did may also be explained in the walk around part I did in this video.

If I have confused you or you have further questions, please post them below or if you don't have a Google account, please e-mail me at migsrus@outlook.com and I will do whatever I can to help you out.  As I mentioned earlier, it is an ambitious set of modifications, so I would suggest taking your time, measure carefully and don't hesitate to ask questions... :) 

Cheers,

Scott

The "serious" :/ and "silly" :P sides of RC

Hi everyone -

With the crummy fall weather we have had for the last few weeks here on the "Wet" (west) coast of Canada, I have probably been spending more time than is healthy watching You Tube while waiting for glue to dry on my two latest builds... :/  Yes, I know, I have already asked Santa for a life for Christmas... :)

Anyway, there are a couple You Tube channels to which I am subscribed that are kind of at the opposite ends of the RC spectrum, but both informative and/or entertaining.

I have been watching Bruce Simpson (from New Zealand) and his RC Model Reviews channel for awhile now https://www.youtube.com/user/RCModelReviews  It is great for technical type education, he just posted a great video on how carbon fiber and electricity don't mix.  I get e-mail alerts when he posts a new video which allows me to decide to watch or not since there is a lot that is not really of interest to me, but every once in awhile he has some real gems that are great from a standpoint of general education about RC gear.  He also does good reviews on new gear (most of it from Hobby King) once in awhile.  He has done great comparisons of transmitters, etc and is very honest in his assessments from what I can see.  He does maintain a website as well, but it is not always that current from what I have seen.

If you enjoy British humor, there is a gang of fellows from the UK at spocktra50 https://www.youtube.com/channel/UCNoqABZOzSk74bnPeI1BnSA  that are like watching the Monty Python of RC.  They just like to have fun and don't take themselves or each other too seriously, good for a real chuckle.  The language does get a bit colorful at times, but I find them absolutely hilarious, and they have a great time together which is what this hobby should be about at the end of the day, having some fun (at least in my opinion)... :).

Cheers,

Scott

RCP Mig29 V4 NAMCV3 walk around and flight video

Hi everyone -

Just posted the walk around and flight video of my RCP Mig29 V4 NAMCV3.  Hopefully the walk around will show and explain in a little better detail some of the modifications I made.  Unfortunately, grey sky and mostly white plane it gets washed out several times on the flight portion, but then you get to listen to my scintillating commentary... :/

I plan on doing another "fly off" with the NAMCV3 and NAMCV2 Migs while I still have the Focal Price motor in it, then after that will upgrade to the NTM 2700 power system and start seeing what sort of speed I can get out of this little beauty... :)

Tomorrow does not look like a good day for flying, so I will focus on getting the pictures, drawings and supporting documentation complete on all the modifications I did now that I know it flies so well.  Those will be posted on the blog as soon as I can get them done.

Just wanted to share a logo that one of our contributors RT designed with our newly adopted motto... Think, Design, Test, Validate.  Thanks RT... :)

Cheers,

Scott

RCP Mig29 V4 NAMCV3 post flight report

Hi everyone -

I'm a very happy park jet pilot today, not only because it was the first time I got to fly in over a week, but I also managed to get the maiden flight done on my new RCP Mig29 V4 NAMC3... :)  It is the white one in the picture below, the green and brown camo plane is my stock built RCP Mig29 V4.

I must admit, I was a bit apprehensive about this maiden flight because of all the modifications I had made WRT to shortening the plane and moving the motor forward.  But luckily for me, the RCP Mig29 didn't let me down... :)  I managed to blast 10 batteries through my new plane today, very happy... :)

Fortunately the weather gods were on my side today as it was pretty much dead calm, great conditions for a maiden flight.  As mentioned in a previous post, I started off with the plane balanced dead on the CG per the plans and other than moving the battery ahead maybe 1/8" after the first flight to help keep the nose down at top speed, it balanced right on the CG per the plans.  This is interesting to me as with all my previous Mig V4s including stock, they all balanced about 3/4" to 1" ahead of stock CG, so moving the motor forward and shortening the back end of the plane brought the CG back about 3/4" from what I had been experiencing on all my previous Migs.

I have my battery almost all the way to the left side of the battery bay as shown in the picture below to have zero trim in the roll axis.  The tip of the screwdriver annotates where the CG is on my plane.

This plane felt rock solid and balanced from the minute it left my hand on the maiden flight... :)  By having all the weight, servos, motor, Rx, ESC and battery all within a 10.25" span on the plane, it is without a doubt the most precise and tightest feeling Mig of all the Migs I have built and flown.  Not that the others are sloppy, but the precision and balance on this plane is about the best I have felt in any plane I have flown to date.

It is very responsive, but not twitchy in all three axes (pitch, roll and yaw).  It just goes where I point it effortlessly and precisely with no wasted movement or energy.  The really interesting thing is that I would say I need about 10-15% less control input in all axes with this plane than with the other Migs I have in my hangar.  To do a stall turn, I just barely need to touch the rudders and it rotates smoothly without rudder roll.  In fact, if I put on the same amount of rudder deflection I do with my other Migs, it will start to rudder roll, but with just a delicate touch, it stall turns effortlessly.

Turns are rock solid, it just carves it's way through turns but again without being twitchy or sloppy, it just finds it's line and goes where it is supposed to.

Rolls are crisp in both directions, I almost get the feeling like there is a rod right down the centreline of the plane that the plane is revolving around, very tight rolls with little control input.

As expected with being 2" shorter than stock it is very responsive in the pitch, but without being too aggressive, again, it finds it's line and just carves through loops.

Where it really jumps ahead of the other Migs is in slow speed flight and high alpha.  I think that because of the motor and the centre of thrust (CT) being so much further forward coupled with the battery almost all ahead of CG, it just settles into slow flight and high alpha with amazing stability.  I was able to comfortably fly it around at about 35% throttle and it felt very solid and stable.  With my other Migs at times flying them that slow I feel like I am on a razor's edge most of the time, with this NAMCV3 Mig, it is much more forgiving at slow speed.  It settles into and maintains high alpha more easily than my other Migs although with the increased effectiveness of all the control surfaces, I will need a bit more practice getting the rudder throws and expos dialed in to keep high alpha smooth and stable when turning.

Like all the other Migs, it is very stable at speed, the faster it goes, the more stable it becomes.  In the video I mentioned it seemed to reverse torque roll at full throttle, but I discovered this was due to one of my rudders not being completely dead center :/ , so after adjusting that, problem solved... :)

Perhaps because almost all the battery is ahead of CG, on landing it does need a little more up elevator to hold the nose up and flare nicely on landing.

So despite some of my initial trepidation over how it would fly with such ambitious modifications, my stress was for not, it flies absolutely amazing.  Although I have not yet analyzed it's wind stability, in all other aspects it is amazingly crisp, solid and stable.  Being that much shorter than the other Migs and having all the weight so centrally located, it just feels so tight and precise.  Again, not that the other Migs were sloppy, but I feel this plane is tighter in everything it does, no wasted movement or effort, it just gets the job done better in every way.

I have walk around and flight video processing now and will hopefully have that posted on You Tube later today.  Then my next project will be to get a usable set of drawings, pictures and supporting documentation done to support and explain all the modifications I made to this plane.

So not sure what is up next for me, I think probably another FRC Su35 MK2 with the motor moved forward significantly after seeing how doing that improved slow speed handling on this version of the Mig29 V4.  But maybe a bit of a break first til my building buddy Bently gets his strength back...guess I have been working him too hard lately... :/ ;)

Questions or comments?  Please leave them below, or if you don't have a Google account, feel free to e-mail at  migsrus@outlook.com 

Cheers,

Scott

RCP Mig29 V4 NAMCV3 Build complete

Hi everyone -

Managed to finish off my RCP Mig29 V4 NAMCV3 today, well at least to the point where I can get it flying and test it out before paint and a bigger power system.  For now I just put on a little painter's tape and some magic marker for contrast so I can track it for the maiden and test flights.

A couple of comparison pictures with my stock Mig29 V4.  I know it is kind of hard to tell because of the angle of the pictures, but the NAMCV3 is 2" shorter than the stock Mig.  

Hopefully you can also see how much shorter the front part of the fuselage is due to the motor being moved forward by 1".  Also, the elevons are more square on the V3 compared to being more tapered on the stock Mig.

In the picture above, you can see how much smaller the intakes/nacelles are to accommodate moving the motor forward and shortening the fuselage behind the prop slot.

Picture below of the trailing edge and rounded wingtip of the "Mig35ish" wing.

Picture below shows the distance between the trailing edge of the wing and the horizontal stabilizer.  It is now 1.5", on the stock Mig it is 2.25".

Below shows the position of my battery to balance right on the stock CG per the plans.  This battery location is about 1.5" behind where my battery is on my stock Mig and my NAMCV1 and V2.  If it ends up staying anywhere near this location, all of my weight, battery, motor, ESC, Rx and all six servos are within a 10.5" area which will be awesome for aerobatics... :)  The tip of the pen in the picture is pointing towards where the stock CG is located.

So here are some of the key dimensions on the NAMCV3 compared to stock

Wingspan - V3 is 27.5", stock is 27";

Length - V3 is 39", stock is 41";

Elevon span tip to tip - V3 is 17.75", stock is 18.5";

From nose to motor mount - V3 is 23.75", stock is 24.75"; and

Distance from the prop to the elevon hinge - V3 is now 9", stock is 8"

Overall, other than the fact it doesn't look that great right now as it isn't painted, I am very happy with how it looks and how it turned out.  Other than the fact it doesn't have a dual seater canopy like the Mig35, I think it looks a lot more like a Mig35 than a Mig29 which was one of my goals... :)  The real proof of concept can only be assessed at the field.  I am hoping to maiden tomorrow if the forecast holds.

My weight as is right now is 21.5 oz which is about the same as my stock Mig, so it will allow for good comparison between the two to see how the modifications affect how it flies compared to stock.  Once I have that testing done and the proper CG sorted out, I will paint and put in the NTM Prop Drive power system for some real speed, that should bring my weight up to about 25 oz which is normal for an NTM equipped plane in my experience with the MG servos for the elevons and the extra carbon fibre reinforcement.

So I am excited to see how it flies as this is the most ambitious set of mods I have ever done on a Mig29 V4 to this point.  I will do a walk around before flight and write a more detailed post on the build after I get some test flights done.  

Should be exciting... :)

Cheers,

Scott

Flight Test Report, Forwards or Backwards with Cg?

Yesterday was an interesting flight day.

Mig-35v2 is on left and Mig-29v4 is on the right. 

I took out the Migv4 with straight vertical rudders like Scott's and inboard ailerons.  It has the stock elevons.  This plane is dialed in and a lot of fun.  So I decided to experiment.  It may have been an earlier post of Scott's, but somewhere I read about setting the CG.  You climb at about 50% throttle nose up at 30 degrees and cut the throttle.  The plane should continue climbing in a slow arc and then enter into a slow nose down descent.  I did this repeatedly and kept pushing the battery towards the back.  Bad habit from my fuelie days, but I've always flown nose heavy and I am kind of hardwired for that feel. The more I pushed the battery back, the more I felt like I was going to lose control but I didn't.  The airplane felt much lighter?  Not sure how to describe it. 

 As expected, vertical maneuvers were much easier and looked more natural and graceful.  Not that my goal is to hover, but I did and was able to do a really nice tail slide.  Rudder stall turns were easier as well.  I've always dialed my planes to no trim at 50% throttle, I didn't check to see where this one would be with the Cg moved back.  I am going to play around with this some more.  The old sphincter got a little tight as I pushed her towards neutral CG COL, but wow what a new flight experience.  

I also flew the Mig-35v2 with downsized  wing and LERX.  I swapped the FP from my F22.  What an improvement over the Turnigy 2200.  I need to work on dialing this plane in some more.  I think I have the Cg too far forward.  The plane weighs 3/4 oz more than the v4, but amazing the battery is way in the back for the same Cg.  The tail plate cut out perhaps, not really sure why the difference.  Here's a couple of picks.  Once I get them both totally dialed in I'll measure the Cg as compared to stock.  I'll measure the Cg from the nose of the plane to make it easier for us to compare--since I've changed the wing and LERX.

Hopefully weather will hold and I'll fly some more tomorrow.  Once I dial the Mig-35v2 I'll do a video.

A la votre!

Stephan

Puto, Consilium, Test et Convalidandum

How about that for our motto?

Think, Design, Test, Validate

Woohoo

Off to the flying field for the first time in a couple of weeks.  

Mig-29v4 with stock elevons vs Mig-35v2

Prost,

Stephan

Mig29 V4 and Su35 MK2 NAMCV2 flyoff

Hi everyone -

The weather gods were on my side today and I managed to actually get out and fly... :)  Calm winds, cool, dense air, perfect day to put a couple of jets through their paces.  Took my two favorite Russian park jets out to the field to do a bit of a fly off.

The blue camo Mig on the left is the RCP Mig29 V4 NAMCV2 (I'll just refer to it as the Mig for the rest of this post).  It is modified quite a bit from stock, you can read the build details and modifications here http://migsrus.blogspot.ca/2014/09/rcp-mig29-v4-namcv2-build-complete.html

The yellow and brown camo Su35 on the right is the FRC Su35 MK2 NAMCV2 (I'll just refer to it as the Su for the rest of this post).  It is highly modified from stock, you can read the build details and modifications here http://migsrus.blogspot.ca/2014/10/frc-su35-mk2-build-complete.html

I know some of this comparison is kind of the old comparing "apples and oranges" dilemma, but I learned a lot today about motor position in the airframe and how the distance between where the prop is in relation to the rear control surfaces (elevons and rudders) impacts flight performance.  This couldn't come at a better time for me as I am playing with some pretty significant modifications on my latest Mig29 NAMCV3 build that I am kind of "morphing" into a Mig35.  Part of that modification involves adjusting the motor position forward and shortening up the distance between the trailing edge of the wing and the tail assembly.

I will present my impressions of how these planes handle in relation to each other, then if you are interested, I am going to dig a little deeper into some measurements and try to see if I can put some scientific logic and explanation as to why these planes handle how they do.

Firstly, both these planes are about the same weight, very close to the neighborhood of 21 oz with a 2200 battery.  Both have the same motor, the FP 2700 with 6x3 EMP prop, same controls, elevons, ailerons and rudders.  In fact the rudders are essentially identical in size and shape as I used the Su rudders as a guideline when I modded the Mig rudders on that plane.

The throws are essentially the same in all axes within about 5%.  Where the big difference is that in the pitch and roll, I have about 10% more expo on the Su than on the Mig.  I may have mentioned it before, I am kind of a "muscle memory" flier in that I have kind of a certain amount of stick movement programmed into my brain and thumbs to generate certain pitch and roll rates especially.  To accommodate this, I adjust my throws and expo so that as I transition between each plane, my stick movements remain very much the same without over banking, over pitching, etc.  Hopefully that makes sense, if not please ask and I'll try to explain it more clearly.  Anyway, to keep the Su a bit more docile so that I don't flail it around too badly in turns and basic maneuvers, I threw in a bit more expo to accommodate my muscle memory and soften it's responses.

Speed and stability

Above half throttle, both planes are very stable, so close that as John Wayne once said "I wouldn't want to have to live on the difference" :) .  They are both very stable in calm and windy conditions. They are essentially the same speed at full throttle.  The Su however is a bit more susceptible to a bit of torque roll on occasion when hammering on full throttle.  Doesn't always happen and nothing that can't be corrected with a tiny bit of opposite aileron, but it is noticeable.  On the Mig, I don't think I have ever seen it torque roll.

Where the big breaking point comes with respect to speed and stability is when you start to get slow, below half throttle.  The Mig stays very stable down to about 35-40% throttle, very few bad tendencies unless you get too aggressive with the sticks when you are slow.  The Mig is also capable of very good high alpha, with angle of attack (AOA) of about 35-40% fairly easy to maintain with the aid of a bit of spoiler deflection.  

Slow speed is where the Su really starts to drop off in performance, it is flyable in calm conditions like I had today down to about 35-40% throttle, but you really have to stay on top of it.  If you lose focus for a few seconds, it can become a very unhappy park jet very quickly... :/  I have never really played around with any serious high alpha with the Su as I find as soon as I get slow and get about 25 degrees AOA, wing rock comes on quickly and violently and the only course of action is to drop the nose and fly out of it, no bringing it back right away like I often can with the Mig.

Pitch axis

The Su is more responsive and aggressive in the pitch axis in turns, loops other maneuvers that are "pitch centric".  It does however require a bit more finesse on the sticks with respect to control input and power management or it can very easily "over pitch" or even get to the point of thrust vectoring (TV) stall (when speed gets low and with too much elevon deflection they act as speed brakes rather than elevons).  The Mig is also very responsive in the pitch, just not quite as aggressive and is more forgiving through loops and other pitch maneuvers not requiring as much finesse or focus on power and control inputs.

Roll axis

The Su again even with more expo is quicker and tighter in the roll axis than the Mig.  Slightly shorter wingspan might contribute to that performance, but it is more responsive in the roll than the Mig.

Yaw axis

Both are very responsive in the yaw, rudder authority is excellent in both, in fact I used Su inspired rudders on the Mig, so that is probably logical.  The Mig still occasionally has a bit of "rudder roll" when executing stall turns, the Su not so much.  However, if the rudder is held over too long through a stall turn with the Su, it will start to seriously spiral and do some pretty funky things...all while heading straight at the ground... :/

Overall handling and impressions

Both these planes in their current configuration are a lot of fun to fly and it might just be a matter of what you are looking for on a given day.  

The Su that I am flying now is highly modified from stock, many of the features I added were to build in more stability to come into line with my flying skills and abilities.  I used the toed in vertical stabs and split horizontal stabilizer and elevon from the RCP Mig29 V4 to enhance stability and am pleased to say it does work really well to tame this plane down from it's stock configuration, at least in my experience and at my skill level.

Both planes track exceptionally well, really carving turns with no hesitation, both are very precise and crisp in their maneuvers.  As already mentioned, above 50% throttle, I would give the slight nod to the Su as being the more agile and aerobatic, but a bit more focus and concentration is required when flying it to prevent problems. 

The Su tends to slow down more quickly and lose energy in aggressive maneuvers if I don't anticipate correctly and manage it's speed correctly.  The Mig tends to not need as much throttle management through the same maneuvers and maintains and regains it's energy better than the Su.

As already mentioned, where the real difference in performance and versatility happens is in the slower flight regime, less than 50% throttle.  The Mig wins there hands down.  It stays predictable and forgiving even down to about 35% throttle and does high alpha very well.  The Su can be managed down to about 35% throttle, but if I lose focus for one second and don't anticipate adding some power in turns, it can bite me, stalling out and dropping a wing or it's tail very quickly.

From a standpoint of versatility in power setups, I would also give the nod to the Mig.  I have built and flown the Su with the NTM 2700 and I know lots of folks have had success with it using that bigger motor, my experience was that it (in stock configuration mind you) did not like the extra power and weight and was a real handful to fly.  This weight of about 21 oz with the FP 2700 motor is the perfect setup for me where the Su is concerned.

So again, it boils down to what you like or what you want.  In the configurations I flew both these planes, the Su is more nimble and aerobatic above 50% throttle, although it does require a bit more focus and concentration when flying and is not as forgiving as the Mig.  The Mig is more forgiving and more versatile over a much larger speed envelope than the Su from my experience, so again, all depends on what you want.  I often take one of each to the field and fly them both as I mentioned, both are a real blast to fly in their NAMCV2 configurations.

As I was flying and after I got back from the field, I really started wondering what was going on between these two planes and how their setups affected their performances.

So just a few quick measurements and a couple more pictures that might put things into perspective on the differences and similarities between these two planes.  I took the time to measure all these distances on my planes as they are rather than using the stock measurements off the plans since both my planes are modified.  I know some of the measurements may seem a little weird and I may or may not use them in my discussion, but since I had the ruler out anyway, what the heck?

Mig

• Wingspan - 27";
• Length - 40" (one inch shorter than stock);
• Distance of CG (based on where I found my CG to be which is about 3/4" ahead of stock on the plans) from the nose - 20.75";
• Distance between trailing edge of the wing and the horizontal stabilizer - 2.25";
• Distance from the nose to the motor mount - 24.75";
• Distance from the prop to the elevon hinge line - 8.25"; and
• Distance from the prop to the rudder hinge line - 6.5"

Su

• Wingspan - 26";
• Length - 35" (one inch shorter than stock);
• Distance of CG from the nose - 20";
• Distance of trailing edge of the wing to horizontal stabilizer - 1.5";
• Distance from the nose to the motor mount - 25";
• Distance from the prop to the elevon hinge line - 4.875"; and
• Distance from the prop to the rudder hinge line - 3".

A couple things to note right away, compared to the real Mig29, the Mig is very close to scale, it should be about 41" long (which it is stock, not with smaller elevons like I have).  Compared to the real Su35, the Su is 2.7" too short based on my current build.  Even stock it is almost 2" too short to have scale proportions.

Some interesting measurements when you look at how much shorter a distance there is between the elevons and rudders and the prop on the Su.  I think this has a lot to do with it's snappiness in the pitch.  Also, in relation to the whole length of the airplane, the CG on the Su is further back, pretend the airplane for a minute is measured in percentages from front to back, the CG on my Su is at 57%, the Mig is at 52%.  

Also, if you look at this picture (I tried my best to take a bird's eye view from the top) you can see that the motor on the Mig is almost completely centred in relation to the chord of the wing.  Whereas with the Su, the motor is almost at the trailing edge of the wing.  For the sake of this discussion, lets call the motor/prop location the centre of thrust (CT).  Not only from the picture but when I do the math, there is a significant difference where the CT is on each plane in relation to it's total length.  There is 38% of the Mig behind the centre of thrust, but only 29% of the Su behind centre of thrust.

I know perhaps this might all be getting too complicated, but when you think of where the CG and the CT are in relation to the length of each airplane, I think it has a big impact on why they perform and respond how they do.  For me, it is a simple matter of levers really.  There is a lot more of the Su ahead of it's CG and CT, but once you get that lever moving, it rotates more aggressively than a more equally balanced (front to back in relation to it's CG and CT) Mig.

The relationship of where the prop is compared to the control surfaces also has quite a bit to do with it.  Also, if you look at the pictures above and below, the prop on the Mig is ahead of the leading edge of the vertical stabilizers while the prop on the Su is between the vertical stabilizers.  On the Mig, the prop wash has more chance to dissipate after it comes off the prop, on the Su it is funneled directly back between the vertical stabilizers, hitting the elevons with much more concentrated force than the Mig.

Just spitballin' here, but I think that both these situations are good and bad.  The Mig is still getting good thrust vectoring (TV) authority, but responses are not quite as immediate and aggressive as they are on the Su and while still very responsive, the Mig is a little more forgiving in the pitch especially.  While the Su is more aggressive, this also has it's downside as without managing the power and control input properly, the Su can TV stall much more quickly than the Mig, causing the plane to slow down very quickly, lose energy and then well...things can get very ugly from there... :/

Also, when looking at how much of the plane is ahead of the CT and CG, it might explain why the Mig is better balanced in slow flight and high AOA situations.  I remember Dave Powers in one of his old videos demonstrating how when you try to balance a long stick vertically on your finger, it is very hard to do and very unstable as the long stick is acting like a big lever.  However, if you balance a pencil, it is a much smaller lever and much easier to balance vertically.  

Perhaps this is what is going on between these two planes.  Much less of the total length of the Mig is ahead of the CG and CT than with the Su, so when you try to balance the Su at a high AOA, there is a much longer lever to balance on the pivot point.  This does make for some very nice flips over the top on slow loops, but it might be an interesting experiment to move the motor/CT a bit further forward and see what happens.

Not that I am interested in hovering a park jet by any means, but when I watch the promo and hovering video of the RCP Su30 V4 with it's motor very far forward, it again confirms that less lever above the CT is easier to balance at higher AOA.

Getting out my dollar store calculator once again, to bring the CT on the Su closer to that of the Mig, means moving the motor forward by at least two inches.  Perhaps that might be a bit drastic, so more measuring, calculating and assessing will have to be done.  Here I go again, talking myself into another project... :/  But I am up to the challenge and very interested to see what the results will be.

So I guess in conclusion, it all depends on what you are looking for.  To get the Su I am flying now to where it is, there was certainly a lot more modification required to get it to be smoother and more stable over stock, with the Mig not so much.  The Su being smaller and with a CG and CT further back tends to be more nimble and aggressive at higher speeds, but performance drops off at lower speeds compared to the Mig.

I am thinking that there could be still more mods done on both, as mentioned I am kind of currently "morphing" a Mig29 into the more modern Mig35 and I can see more potential with the Su35 by not only moving the motor forward a bit, but perhaps also stretching the back out a bit further...oh dear, the wheels are turning now...how much more depron do I have?!  :)

Cheers,

Scott