I have started the real work on the next evolution of the RC Powers Mig29 V4, the V4M3e3, a cooperative modification setup of the NAMC (North American Mig Consortium). This is kind of a fun thing that Stephan Moran and I came up with as we have been working together for a few months now brainstorming, tinkering, modifying and testing modified RC Powers Mig 29 V3s and other planes. Stephan did an awesome job of designing a patch for us that will be going on all my future Mig builds... :)
I know these are a lot of acronyms, but Stephan and I are both veteran Air Force officers of our respective countries and without acronyms our vocabulary would be cut in half! For those who haven't read the posts on the V3M3e3, the M3 stands for (Moran Modified Mig and e3 for me, e3Scott).
Anyway, on to the good stuff! Stephan and I have pretty similar flying styles and are constantly in pursuit of that perfect setup of speed, scale looks and handling, crisp, precise aerobatics yet smooth and stable so that the plane allows us to push it and our own skills to the limit without the plane biting back too hard.
I have already built and flown a stock Mig29 V4, I have 117 flights on that plane now. In stock configuration it is a dramatic improvement in all areas over the Mig29 V3. However, it does at times have "weather vaning" issues in the wind where as it is in a crosswind turn, the elevons get pushed out by the wind and it ends up doing more of a drift turn than a nice steady tracking turn. And it could also be tightened up in a few areas to better suit our flying style, so the experimentation begins... :)
Stephan and I have worked together and proven on three different planes, the Mig29 V3, the F18 V3 and the FRC Foamies Su35 MK2 that smaller elevons, ailerons and rudders with vertical hinges and trailing edges work awesome and are much better suited to our flying style(s).
So, here are some pictures to show the new surfaces. The first photo shows the reduced elevon surface bringing it more into scale proportions and to the surface area that Stephan and I found worked well on the V3M3e3. The reduced drag of the smaller surface increases speed as well as providing crisp/precise control without increased drag and turbulence when the control surface is deflected. I would venture to guess that the overall reduction is only about 10%. The stock elevons on the V4 are smaller than those on the V3, so the amount of reduction was less than with the V3M3e3, so hopefully this will help a bit with any "weather vaning" in crosswind turns. The back deck on the V4 is much larger than that on the V3 since the motor is moved almost an inch further forward, so that may also be contributing to some of the weather vaning, so a reduction in that surface area by opening up the prop slot a bit more may also be helpful. I will open up the prop slot about 1/2" further back than I did on the stock V4 and see if it makes a difference.
The next photo shows the modified vertical stabilizer and rudder setup. I had to lay out the pencil, highlighter and ruler to show where the rudder is as the score line wouldn't show up well. This in fact makes the plane look more like the latest version of the Mig29 family, the Mig 29M and the Mig35. It worked very well on the V3M3e3 and allows now for the vertical rudder hinge and trailing edge that Stephan and I prefer for more precise overall rudder control in how we like to fly. The rudder surface is 4" high by 2" deep and the entire vert stab/rudder surface is a little smaller than stock which should also help reduce drag and increase speed.
Here is a picture of the Mig35 showing the almost purely vertical trailing edge on the rudder/vert stab.
This next picture shows the reduced size of the aileron that we liked from the V3M3e3. It allows for good experimentation with flaps/spoilers/spoilerons/flaperons depending on what setup we like as they are more in line with where the flaps would be on the real plane. The aileron is moved in about 3/4" of an inch to allow us to run all our servos and pushrods externally thus eliminating any drag/turbulence/interference in the prop slot and prop wash area. In the picture I have cut the aileron along the stock hinge line, it is 4.5" on the hinge and about 4.25" on the trailing edge to allow the inner and outer edges to remain parallel.
The other modification I will make is to increase the size of the KF airfoils slightly by moving the trailing edge back about 1/4". Stephan measured the current KF and they are at about 37-38%. I found that KFs in the area of about 40% worked amazingly well on the V3M3e3, so I will try that out for a bit more stability and smoothness.
If all this testing and trying new things has taught us anything over the past few months, it is that starting with an excellent, stable platform and making our own adjustments makes for an amazing plane that suits our flying style. We have both been very pleased with the V4 thus far and are confident that the V4M3e3 will also be an amazing version of this great plane.
I will continue to update this blog as the build and flying and testing phases continue.
Cheers,
Scott
Scott,
ReplyDeleteVery nice write up the who, the why, and the what!
Being North Americans, I wish there was one of ours that is as good an RC design as the Mig!
I like your idea about cutting back on the prop slot to decrease the surface area of the v4 tail plate, this baby's got back. Through her up sideways in the wide, she shakes her thing all over the sky. This elevon pitch polar effect, aka tail wag, washout or weather vaning is crazy on the v4. If the wind is blowing, I take out my M3e3.
I look forward to this blog, as the administrator you can keep it constructive ;)!
NAMC South of the Border,
Stephan
RTMS (Roll Tide Mig Shop)
There are two points that make the vertical rudder very appealing to me: First, just as you said the vertical rudder controls in a more fluid manner. Part of this could be that only the servo arm arc dictates a non linear movement in the rudder. A swept-back rudder adds another arc and complicates the resulting geometry. The result should be that near the end of the throw the rudder should move less. I'm not explaining this well. I'll draw up what I mean and try to post an image. Second is related to the geometry too. Because the rudder is 90 degrees to the control arm the required torque is less than if the control arm were at an angle. The result of course is longer battery life. You guys rock! Your modifications are so well thought through!
ReplyDeleteHey thanks Dave. I think I understand well what you are talking about. There is also another article on the blog you might have seen called Rudders, Rudders and more Rudders http://migsrus.blogspot.ca/2014/08/rudders-rudders-and-more-rudders.html
DeleteYou have some awesome points there. Unfortunately we can't post diagrams in the comments on the blog, but if you want to send us an e-mail at migsrus@outlook.com, we can include it as an update to this post above to support your comments.
We do our best to think through what would work better after fully evaluating what we have currently, I think that has been one of the biggest keys to our ability to progress with each variation of the Mig29 V4.
The other great thing is that Stephan and I have slightly different taste in what we want out of our rudders, so we are able to test and report a couple different variations depending on what folks seek. But the bottom line is all this thought and testing is to make our rudders efficient, effective and to provide us control in one axis at a time, not yaw and roll together.
We both love the creative aspects of building these park jets, but love the technical aspects of what backs up the performance even more I think, so if you have diagrams, pictures, anything else you want to share, please feel free to e-mail us and we can update any of the posts with your pictures and diagrams so we can all learn.
We appreciate your kind words and your participation in the blog, we are always open to new approaches to things and look forward to hearing more of your thoughts and ideas.
Cheers,
Scott
Dave,
DeleteThanks for the compliments and comments. I am totally with you and understand the torqued angled hinges put on the servos. For the rudder and elevons I am very careful about the angle. For the ailerons I trade off the efficiency loss with the angle for centralized mass a lower polar moment of inertia. I also don't like the look of a servo out in the middle on these wings that are only 15mm thick.
Another area of interest to me is servo resolution and maximizing efficiency. I try to set up my control rods on the servo arms to utilize the full range of the servo. This also applies to the control horn. So ideally on a perfectly dialed in plane, the servo travel and dual rate would be at 100%, the control rod would be at the closest hole on the servo and the farthest hole on the control surface. On my planes I shoot for 90-100% on the settings. Really does make a difference in the fine control.
Stephan