Kudos to NAMC's senior test pilot, Scott. He has been tearing up the skies testing NAMC modifications while I've been enjoying wake surfing down here in Alabama.
I wanted to summarize how we have modified the V4 and briefly explain why.
1. 40% KF Airfoil. The original KF airfoils were designed and tested on straight wings. I can not find any references to swept or delta wings. Between Scott and I, we have tested RC Powers stock airfoils, 40% and even a KF tapered trailing edge. The 40% KF hits the sweet spot and brings the center of lift a little further back.
2. Inboard ailerons, aka moveable flaperons or spoilerons. With thrust vectoring elevons, a lot of roll is generated by the elevons. Stock RCP parkjets fly great without ailerons due to the oversized elevons. Scott and I like full six surface control surfaces and with the downsized elevons, the planes need slight aileron input. Spoilerons allow for a higher AOA in high alpha. With the heavier NTM Prop Drive 2700 setup, I like the to have flaps for takeoff and landing. Best solution for all these flight characteristics is the inboard aileron setup. Bonus, is less tip stalling at slow speeds with aileron input.
3. Downsized elevons. In my opinion, this is the single greatest improvement we have made. For the v4, we modified the TV area of the elevon to accommodate for the decreased moveable area with the new fixed horizontal stabilizer/elevon design. With these planes being so light, and now a lower polar moment with the motor moved forward on the v4, EPPE (wind vaning or tail washout--see prior posts) was decreased over the stock v4.
4. Vertical rudders. The v3M3e3 rudders lacked authority. With Scott's modification of adding to the leading edge of the vertical stabilizer, the vertical rudder is larger giving the extra authority needed. We wanted rudders to generate yaw and minimal pitch or roll.
What's next? I need to build a v4 to these specs. Do we need more rudder authority? Can we decrease EPPE further? The v4 tail plate is pushing my aesthetic tolerance, this baby has got too much back! I will probably narrow the tail plate back to the v3 width. I could remove more area from the front of the tail plate to decrease surface area, but then I don't like to see a big hole in the middle of the plane. Brain is churning while Scott keeps flying the wings off of these planes!! Between the two of us, rest assured, we will figure it out.
Stay tuned.
Stephan
North American Mig Consortium (NAMC) was formed to share ideas, build techniques and test results in pursuit of a park jet that suits our flying styles. This additionally will be a forum to freely post and share ideas and have a lot of fun! If you don't have gmail or google accounts and want to send us questions, please do so at scott@migsrus.com. Your e-mails may be re-posted in the blog to benefit other followers. Puto, Consilium, Test et Convalidandum; Think, Design, Test, and Validate
Great points, Stephan, helps fill in a lot of the technical detail as to why we are having such success with these mods we are trying. I was actually thinking today that it might also be worth trying the V4 style elevons/elevators on other planes I might build in the future like a modded version of the F18 V4, the FRC Foamies Su35 MK2, F15 MK2, etc. After seeing the difference in how much more "quiet" the back end of the V4M3e3 is compared to the V3M3e3, having less surface moving around back there and not having to cut that extra slot in the elevons to accommodate the outboard pushrods I think just makes the whole thing smoother and more stable allowing for cleaner flow of air. That is a significant change that RC Powers made on two of the planes in the V4 lineup and I think a real improvement in many ways.
ReplyDeleteI'm excited to see how much more of a reduction in surface area we can squeeze out with bringing the back end more in line with the V3 width...narrowing that back end and then slapping an NTM Prop Drive on there...hmmmm, I think the 110 mph barrier is in serious jeopardy... :)
And I will continue to fly the wings off this plane, it is seriously addicting having such a great performing plane, we keep setting the bar higher and higher with each evolution of our ideas... :)
Cheers,
Scott
Scott,
DeleteThe V4 style tail end is going back to "old school" aerodynamics. For good reason on conventional airplanes and RC designs, the fixed portion is called the horizontal stabilizer. The only difference now between the V4 and a traditional design is the elevator is split and functions as elevator or elevon. With the real Mig and similar war birds, they have the benefit of computers and true thrust vectoring which allow them to take advantage of elevon only type design without a fixed horizontal stabilizer.
The SebArt Mig has the v4 type horizontal stabilizer/elevon setup.
You're right, applying this design to your favorite other park jets would be awesome.
Stephan