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Posted by mejmea | Oct 20, 2016 @ 04:47 PM | 917 Views
The video below briefly describes the components I used to convert my Parkzone UM Mosquito from non-as3x/brushed to as3x/brushless. It also shows a visual comparison of the static thrust so you can get an idea of the improved performance as well as a flight video of the conversion.

UMX Mosquito 1S Brushless Conversion (6 min 28 sec)

The following outlines further detail of what I did to convert my Parkzone UM Mosquito to 1s Brushless and AS3x. Like most things hobby-related (and in particular RC related) it’s probably not possible to justify the cost and time other than the fact that it is a fun challenge to improve the performance of an already cool model. I find that this conversion makes the aircraft much more fun to fly and also much more flyable, particularly in windier conditions where you wouldn’t be able to fly it stock. If you choose to follow the same path, I expect you too will find the result rewarding but it does require some technical skills and independent thought to adapt to your particular situation. I’ve done my best to describe what I did accurately and am happy to communicate about any questions that may arise but I cannot be responsible for what anyone else does or for any damage to their equipment or aircraft.

A brief history:
When I originally performed this mod I kept the stock 110x80, 3 blade, counter-rotating props. It flew much better than stock but I still wished for a bit more top end speed. I...Continue Reading
Posted by mejmea | Jul 13, 2016 @ 06:45 AM | 1,605 Views
The 2s Horizon Hobby UMX P-47 is a great little flier but a number of people (myself included) have had issues with the decalage (horizontal stabilizer alignment) being WAY off out of the box. This generally causes the plane to climb like crazy - almost like it's very tail heavy. While it's frustrating to have to fix a new plane right out of the box, the solution is actually very simple to implement.

The image below shows what I have found the horizontal stabilizer alignment should be for the aircraft to fly well. This post shows a picture of mine as it was out of the box (climbed like crazy), another picture with too much correction (wanted to dive), and then one with the final adjustment (same as the image below but without the line drawn in). This post shows the methodology to fix the issue if you have it.
Posted by mejmea | Feb 06, 2016 @ 09:03 AM | 1,925 Views
I own a LX Models F4F Wildcat from Banana Hobby. IMO, one of the very cool things about a Wildcat is the way the main landing gear is constructed and retracts. It's a complex set up and as a result you don't see many examples of it in the modeling world. The LX Wildcat actually has retractable gear which is one of the things that attracted me to it. Unfortunately, the way the retracts were implemented leads to them going up or down VERY fast which doesn't look great.

After playing around with various ideas I devised an add-on circuit that will slow down the retracts on the LX Wildcat by roughly a factor of 2. While still not scale (the retracts on the actual Wildcat were hand cranked) I think this mod makes the retract sequence look significantly better although that is, obviously, a matter of opinion. It would be nice if they were still a bit slower but without a complete re-design of the original retract controller board I don't know how to do any better than this.

There is a YouTube Video here and I've attached a write up with further detail on how to create this mod yourself to this post.
Posted by mejmea | Nov 17, 2015 @ 10:17 PM | 2,628 Views
In case it is useful or interesting to anyone, below is some performance data I took a few weeks ago related to using different pinions and propellers with the standard 1S UMX gearbox, the BLH3327 motor, an XP-7A esc, and an Eflite 150mAh 45C battery

Test notes:
- I used a UMX P-40 and a UMX P-51 (V1) as the test-beds. Ideally it might have been best to use just one aircraft to eliminate variability in drive train but it was easier this way and I don't think it really influenced the results.
- Each test was run at WOT until LVC was reached. The results shown below are for one battery. I ran a parallel set of tests with a second battery. The second battery turned out to be weaker than the first. As a result they simply confuse the overall picture so I didn't include them in the graphs below. The trends between different pinions and props were similar between the two batteries however.
- Prop RPM was measured with a standard optical/visible light tach
- Thrust was measured by hooking the tailwheel of the aircraft to a small load cell and letting the plane pull against the cell while resting on its mains.
- RPM and thrust were not measured simultaneously because my set up didn't allow that to be easily done. Thus the graph where thrust is plotted as a function of RPM is the compilation of data from separate runs. Not ideal but...
- My personal preference is to use a scale looking prop as opposed to going for the absolute best performance. Hence I...Continue Reading