Had my two favorite Russian park jets at the field today, my new red, white and blue Mig29 V4 NAMCV3 on the left and my yellow, tan and brown FRC Su35 MK2 NAMCV2 on the right.
It was a very exciting day at the field to say the least... :/ I have the NTM Prop Drive 2700 motor in the Mig29 V4 NAMCV3 now (I took it off for the picture below to make the repairs a little easier). I had done three flights on 3S (more on that later) and one flight on 4S (more on that later too... :) ) and was just getting ready to shoot some video, when I noticed that the foam behind the glue joint on my motor mount was cracked :( ! The glue joint held up just fine, but the foam cracked all the way across. I guess the serious stress the NTM on 4S put on it pushed it beyond it's structural limit, but no fear, plane otherwise is fine. I have marked where the fault line is below with black magic marker to make it easier to see in the picture. So anyway, video will have to wait for another day :(.
So as I continued to fly my Su35, I started wondering how to repair and strengthen this weak area. So once again the dollar store came to the rescue as I had some popsicle sticks laying around and I cut some lengths of that, laid in a good coat of epoxy and so far, it is super strong...only field testing will prove if the repair is solid, but I'm pretty sure it will hold... :)
I will also swap out the prop I have on the motor, it was balanced, but has had some use, so time for a new one to ensure I am not still sending any vibration into the motor mount. Anyway, a small setback and fortunately no loss of aircraft and a 10 minute repair and I think we are once again ready for some more serious speed... :)
So here is the really good news for us speed demons... :)
On 3S, I clocked four solid speed runs of 97, 92, 90 and 90 with this setup... :)
On 4S, I clocked four runs of 115, 111, 102 and 100...wow!
The speeds diminish as the battery loses it's punch from being fully charged, but four runs of 100+ mph on 4S is crazy! The first two runs are faster than the top speed I got with the Mig29 M3e3, so this is a pretty quick little plane.
I just looked back through my flight log, the top speed on 3S I achieved with the Mig29 M3e3 was 94 mph. On 4S, my speeds were 109/108/104/102.
So this is the first time I have broken 110 mph with a plane built with relatively stock setup...gets your heart rate up seeing something you built from foam and glue go by you that fast... :)
So onto overall performance with the higher weight and heavier power system.
My CG ended up moving forward by about another 1/8", so it is now about 1/4" ahead of the stock CG marked on the plans. The battery is moved forward about 1/2" over the FP setup, so this makes some sense to counter balance the heavier motor and the "average of mass" has been moved somewhat which will slightly affect the location of the CG based on the info at this link from NASA http://www.grc.nasa.gov/WWW/k-12/airplane/rotations.html
In flight, any aircraft will rotate about its center of gravity, a point which is the average location of the mass of the aircraft.
It has been awhile since I flew an NTM equipped plane, so perhaps some of what I am about to say is because I am a bit rusty on managing this kind of power, but since I also have the weight concentrated around CG much better than on any other NTM plane I have built, some of this makes sense besides my lack of skill... ;).
Everything happens faster with this plane with the higher wing loading and more powerful, higher torque motor and I don't mean just from a stand point of speed. It is more responsive in all three axes without feeling heavier than it was with the Focal Price motor setup. It does take a little more room in which to turn and fly as even at half throttle it is going fast, but "on the sticks" it didn't really feel like the wing loading had gone up a huge amount even though the overall weight went up by 15% with painting and the bigger power system.
So I actually toned down the throws in the pitch and roll by 10% and increased the expo by another 10% so that I didn't over control it. At speed, it is rock solid stable and it almost seems like the faster it gets, the more stable it gets, it just screams ahead with no hesitation or bad habits.
So still more testing and another round of speed trials to come. I'm not sure actually when the foam behind the motor mount cracked, if it was loose most of the time, I'm sure some of the speed could have been lost from that. I hope to get back out again Friday, the forecast for the next two days is not good. Very pleased with how well this plane flies at medium weight/power or heavy weight/power... :)
Oh yeah, did I mention it is fast?! :)
Cheers,
Scott
Scott,
ReplyDeleteOh the NTM, just a little taste and all of a sudden you sold your RC soul to the devil. I have lost two planes to this little devil. So addictive, insane, and of course dangerous.
'
My first lesson learned was programming the ESC to brake. Cobras and deceleration maneuvers were insane. All good things must come to an end. I had reinforced the motor mount with hardwood pieces. Still ripped it right off the plane and watch here come crashing down.
On a V4, I used carbon square tubes and expoxyed them to the mount and the carbon spar. I was doing a Cobra and either the prop spinner came off or the prop broke. Either way, the end was the same and she came crashing down. The prop took out all of my control rods on one side.
So lesson learned, treat her like a lady! I will eventually drop the NTM in my Mig-35 NAMCv2, but for now I want to keep this plane! Once I build, your v3, I'll do a swap. When I do build a speed plane, I'll borrow some techniques from AirFlow, the master of ridiculously overpowered RCs.
Be careful when you dance with devil
Stephan