Build Tip: "Ungluing" Hot Glue

While looking at FPV videos (my next RC venture)  I came across this video:
http://flitetest.com/articles/hot-glue-tricks
About the only place I use hot glues in my builds is to spot glue tack welds when shaping the nose and for gluing on my servos.  I've read all kind good and bad advice on the forums about taking servos off without destroying the plane or just cleaning them up to recycle them.  In this video they show how denatured alcohol quickly separates the hot glue.  Holy mackerel, its ridiculous how easy it is!!!! Go get some, now!!  My favorite tip of all time.

Another 2212/6 2700 Kv motor from Deal Extreme

Hi everyone -

I was poking around some more on the Deal Extreme website and found another 2212/6 2700 Kv motor http://www.dx.com/p/a2212-2700kv-brushless-motor-set-for-r-c-toy-golden-silver-361849#.VJWrwsCA



This one appears to be identical to the Focal Price 2700 Kv motor that is still currently out of stock.  I have ordered one to test it out, I will call it the DX Gold motor as I am already running another DX 2700 Kv motor which is black, so it will be the DX Black http://www.dx.com/p/a2212s-2700kv-outrunner-brushless-motor-45134#.VJWw5sCA to hopefully prevent confusion between the two.





The good news about this recent find if it is the same as the Focal Price, Ebay and DX Black motors, it is much cheaper at $9.71 USD compared to $12.39 for the DX Black, $12.29 for the Focal Price motor (if they ever get them back in stock) , $10.99 for the YUSHOP66 (EBay) 2700 Kv motor.

So if nothing else, if the performance matches up to the specs, it will be another source of what seems to be a very popular size and Kv motor these days, especially within the park jet community.  If you buy 3 of the DX Gold motors, the price drops to $8.61 per motor and shipping is still free (although quite slow, expect 4-6 weeks if you are in North America).

I have put about 50 flights now on my DX Black motor and it is running very smooth and strong, a bit peppier than my other 2212/6 2700 Kv motors drawing on average about 37 amps and producing about 444 watts with a 6x3 EMP prop.

More to follow on this DX Gold motor once it arrives and I get a chance to test it on the bench and at the field.

Cheers,

Scott

The Continuing KF4 Conundrum

My RC Holy Grail used to be straight line knife edge flight.  Well, time to move on.  I have always been fascinated with the science and voodoo surrounding KFs.  I have scoured the internet and read everything that is evidenced based as well as the because I said so self believers.  There is a whole lot more voodoo than science, the more I get into RC the less I believe what I read.  Here at NAMC, Scott enormous number of test flights have helped separate the wheat from the chaff.

When I test flew my last prototype, I dialed it in without KFs and then with 40% KF4s.  The designers of the KF4s specified 50% but the community seems to have adopted 40% from the KF2.  When I added the KF4s I had to move the CG forward.  After reading extensively, the center of pressure (COP) therefore moved forward with the addition of the 40% KF4s.  The CG I was using was calculated based on mean area chord and theoretically the optimal CG.  I honestly preferred the feel of the balance better at the MAC CG rather than the forward CG with the 40% KF4s.

For the present build I am going to make 50% KF4s which should move the COP back and into alignment with the MAC CG.  Theoretically at least, I'll soon see and report back.

Low altitude high alpha with a park jet

Hi everyone -

I know the title might sound like a bit of an oxymoron, but in recent testing with a couple of planes working on my high alpha skills, I have noticed a few things with respect to low level high alpha that got me thinking about what is going on.  I could just be speculating here, but perhaps it will make for interesting discussion... :)

When I say low level, I'm thinking mostly here about where the tail and most of the back end of the plane are within about two feet of the ground or in the "ground effect".  So I had to do a little more research to better understand what is normally going on with a plane in ground effect.  A fairly simple explanation (at least one I can understand) is here http://en.wikipedia.org/wiki/Ground_effect_%28aerodynamics%29

So I'm not sure that being at a fairly extreme AOA (angle of attack) in the ground effect is taking advantage of what would normally be increased lift and reduced drag, perhaps I have lost those benefits.  Without benefit of a wind tunnel, I can only go with what I see, hear and feel is going on with my plane as I push it close to the ground in an already challenging flight profile.

So you might say why put myself in such a situation doing this type of flying so close to the ground?  Well, no reason really I guess other than it is challenging and pretty cool, getting that tail down super low and sometimes even touching it to the ground is somewhat akin to a 3D pilot dipping their tail in the water while hovering their plane.  Not the most scale of flying as you wouldn't see a real F18 or Mig pilot try a "tail touch", but fun to play around with.  Very high on the cool factor, but as often is the case, a bit higher on the danger factor.  Like with any extreme flying, the margin for error is pretty small, but fortunately the plane doesn't have far to fall if it does decide to reunite itself with terra firma.

So what I was noticing yesterday as I pushed the limits with the plane I was flying was that as I got closer to the ground, within about two feet, some very interesting things started to happen with my plane.  The closer I got to the ground, I found the controls starting to get "mushy" and sluggish to respond and any minor changes in upward pitch would set off wing rock at a much lower AOA than normal.  I could also hear the prop wash hitting the ground and the sound of the prop changing as perhaps it was chopping through dirty, turbulent air being bounced back up off the ground.

I have drawn this very crude diagram to help explain what I think might be happening.

So what I started wondering with how the plane sounded and handled as it got closer to the ground is whether a bubble of dirty/turbulent air was being trapped behind the prop and under the back deck of the plane, especially as the elevons got closer to the ground, blocking some of the flow of air moving backwards.  This now coupled with the prop being close enough to the ground that perhaps the prop wash was now also getting bounced back up into the plane and maybe even back into the prop, causing the difference in the sound of the prop.  

I could be speculating, but perhaps as the tail of the plane was now starting to "rest" on a bubble of turbulent air as it moved forward so close to the ground, that could help explain why the back end and the controls elevons and rudders were feeling "mushy" and slow to respond or in the pitch far more sensitive.  I know that as soon as I lost my nerve or needed to recover out of being that low, once I got up to about 3-4 ft off the ground, the controls and plane felt much more responsive again.

Anyway, it is interesting to speculate, I definitely think that the prop wash being so close to the ground with the unique mid motor mount/prop in slot park jet style of plane has in impact on high alpha performance.  With a normal puller type plane where the prop would be much higher off the ground, perhaps this would not be as much of a problem, I suspect what I an seeing, hearing and feeling is unique to the park jets I fly.

So how do I recover out of it if (or should I say when... :/) I get into trouble?  Well, again, high on the cool factor is to hammer the throttle and power out of it, but this requires a bit of nerve, especially if the plane is starting to wing rock or do other crazy things.  Hammering the power when the plane is already a bit mushy, slow to respond and with spoilerons still deployed can end up in a fairly aggressive maneuver very close to the ground resulting in less than positive results...been there, done that... :/  It is also crucial that I have a motor that has enough power and instantaneous acceleration to get me out of trouble, not enough power and things can go bad as normally the plane is heading towards something it shouldn't be with sloppy controls and not enough power... :/.  

As crazy as it might sound, normally the safest thing for me to do  is to just chop the power and let the plane "flop" to the ground.  This normally ends up in less catastrophic results, allows me to launch the plane and continue on.

So as I mentioned, I could be speculating what is happening here, but I think what I have said makes sense based on what I have observed is going on.  Anyway, low altitude high alpha might not be for everyone, but as I mention, it is high on the cool factor, allows me to push my skills and focus on really being smooth with the controls... :)

Cheers,

Scott

Merry Christmas!

Every now and then we need a break from our thoughts and time being consumed with Migs.
My wife and I started putting together a Christmas CD years ago that we gave to our friends.  The CDs always start a little crazy for the kids and then wind down to a soothing classical piece.
This year I've gone 21st century and posted it on the web.
Merry Christmas
Stephan
Christmas Music

"Differential spoilerons" for high alpha handling

Hi everyone -

I was out dialing in a plane today trying to optimize it's balance and handling for best high alpha performance.

Since Stephan wrote this great article http://migsrus.blogspot.ca/2014/12/trimming-rc-airplane-determining-cg.html , I have been trimming all my planes using this method and have noticed a much more responsive and balanced plane as a result as well as my CG and components being moved back significantly.  I had obviously just grown used to flying my planes far too nose heavy and didn't really notice until Stephan educated me on these new methods of properly finding CG and trimming the plane for a more balanced and maneuverable setup.  Big thank you to Stephan once again... :)

The planes all rotate much better in all axes which makes general handling and aerobatics much more fun and responsive.

However, as the weight has been moved back and the rotation made easier, I have also noticed the affect of prop wash in high alpha has become more pronounced, especially on the Mig I was flying today.

Stephan and I have both written articles that might help understand better what we mean about the affects of prop wash in high alpha

http://migsrus.blogspot.ca/2014/08/mig29-v4m3e3-hi-alpha-testing.html

http://migsrus.blogspot.ca/2014/08/the-high-alpha-right-turn.html

So today as I was dialing in this plane, I found that right turns in high alpha were a real challenge and that if I took my thumb off the rudder stick, it would do a left turn on it's own, completing a full circle in about 25 ft.  So I suppose I could just turn left all day, but that gets pretty boring after awhile and doesn't challenge my skills much.  So I fought with it, had the tail slide around pretty aggressively a few times as the rudder bit too aggressively in right turns and at one point over controlled/dumb thumbed my way into the ground.  So a bit of a nose "gonk", my pride hurt more than my plane, it will be easily fixable.

But as I did my short, solitary "walk of shame", I started wondering if there was some way I could put a setting in my radio to help offset the effects of prop wash to make high alpha a bit more manageable and right turns not so difficult.

I use a Turnigy 9x radio with er9x firmware, so it is far more capable than I will probably ever utilize, but it is pretty versatile for the price.

So at first I thought about having a switch where when I started high alpha I could select preset rudder trim to the right.  This would help, but would then reduce my rudder travel to the right if I needed it (which I knew I would).  It is also another switch to select in addition to spoilerons which I like to use for high alpha to help keep the plane more stable and the nose up a little higher without too much elevator/elevon deflection.  Not a good option as too many switches spells trouble for my limited skills.

Then I thought, why not have the spoilerons deflect differently?  In other words, have the right spoileron deflect a bit more, helping to keep the plane from pulling left all the time.  I'm sure others have thought of this and use it, but honestly I never have heard or read about anyone using it.  I have always been locked into the paradigm that both spoilerons have to be deflected the same amount in high alpha, drilled into me by whoever had my attention at the time when I was still learning high alpha.

So as I looked at the blemished nose on my plane I thought, what the heck, I've had one crash already, what is the worst that could happen?

So since I can adjust the "weight" or percentage of the spoileron deflection individually in each of the "aileron/spoileron" servos without affecting how the aileron works when spoilerons are not employed, I started off with 10% more weight on the right spoileron than the left.  I should add that this plane requires very little spoileron deflection for good high alpha angle of attack (AOA) and stability, actually only about 1/4" deflection.  So this 10% difference did help, but I felt more could be done.  So through several flights, I increased it by 5% at a time until I had 30% more "weight" on the right spoileron than the left.

Although not eliminating the effects of prop wash completely, it makes high alpha handling much smoother and more relaxing even.  The plane still drifts slightly to the left, but would take about 100 ft to do a full circle on it's own if I let it go and for about 80% of the time flies pretty straight with no right rudder input, requiring just the odd minor correction now and then instead of constant right rudder input like I needed without "differential spoilerons".

This setup made right turns much easier, it still occasionally got hung up/delayed, but about 80% of the time, it only needed gentle right rudder input to come around to the right and it responded almost right away instead of having considerable delay like often happened without the "differential spoilerons".

However, as my sage friend from Alabama (Stephan) has often said, aerodynamics is all about compromise, change one thing, it can often affect another.  So there is a caution I will pass along if you try this that I learned today (didn't result in a crash, just a little more excitement than I wanted at the time... :/).  If I got too slow or didn't have the power setting up high enough when I deployed these differential spoilerons, it would pull to the right and drop the right wing.

I have been able to alleviate some of this again with my radio.  In the er9x firmware I can set the speed with which the function deploys, so I slowed the right spoileron down about 30%, meaning it would take a couple seconds longer to fully deploy than the left one, making for a more balanced transition into high alpha.  This didn't mean once established I could get lazy, as it would still drop a wing or pull right if I got too slow with too little power, but once established, the improvement in handling is well worth the risk in my experience.

So now basically I have 1/4" deflection on my left spoileron and about 3/8" deflection on my right spoileron, doesn't seem like much, but it is a 50% increase in deflection to help with high alpha prop wash.

So if you have a radio that allows for this type of adjustment and have noticed this constant "drift to the left/difficulty turning right" with your planes in high alpha, I encourage you to try it or think about it.  Start off high obviously to allow for recovery if it goes wonky on you and I would suggest starting off with a small difference working up in very small increments until you find what you like.  Just because 30% worked for me on this plane, doesn't mean it will work on all planes or that it will work for you, but even with the slight risk, I mention above, it was well worth the reward with much smoother overall handling and performance in high alpha.

Cheers,

Scott

Trimming a RC Airplane & Determining CG from Mean Area Chord in Airplane Designing

In the background, Scott and I have been working on a Mig-35 version of the RCP Mig-29v4.  We have referred to this plane in many ways including using NAMC.  I have had more time to think than fly and build lately.  As they say, "a little bit of knowledge is a dangerous thing."

In the test flight of my last prototype build, I set the CG using the "arc" method that is basically a powered glide test.  I personally like the arc over the glide method for several reasons.  I prefer to be climbing at altitude when I am doing surface control adjustments; it gives me more room for recovery.  More importantly, the arc method is more dynamic visually.  Another method I found in Googling away my time was to fly inverted and the attitude of the plane and amount of elevator required indicate the CG.  Next time out, I will do all three maneuvers.  Here is a great summary of trimming a RC plane (arc method was found in a different post):

Trimming a RC Plane

How do you determine the CG on a wing?  Off to Google and my textbooks and the best method is to determine the mean area chord (MAC).  MAC is the line that divides the wing into equal areas.  Depending on the wing type, the CG is 25-33% of the MAC from the leading edge for straight and delta wings respectively.  Using my program, I calculated the MAC in two different ways.  First I used the "true" wing lateral to the side plates (blue in picture) and second I used the "full" wing to the centerline of the plane (green).  The picture has a lot of overlays:  the original Mig-29v4 wing, Mig-35 prototype wing, and the MAC drawings.  The black and red CG are what I determined after test flights with Mig-35.  The Mig-29 v4 CG is marked in simple text.  The red CG was where I determined the plane to be very slightly nose heavy and just ahead of the calculated MAC CG for a full wing. Clearly, the "true" wing in blue is not the way to calculate the MAC.

From a design standpoint, now that I know the wing CG,  what is the relationship between the  fuselage and the wing?  It's simple, balanced with varying polar moments (see my prior posts about polar moment of inertia). The CG of a fuselage including the tail but without the wing would intersect the CG of the wing. In RC we have battery and ESC as the movable components to adjust the CG and polar moment.  On my present build that is foam only stage of construction without KFs or components, the CG is presently 2 inches aft.

My next question to ponder is how do the KFs affect the wings center of lift (COL)?  Will they change the COL and hence the calculated CG?  For straight wings from wind tunnel testing, we know the ideal KF is 40%.  There is no similar data on the best KF ratio for swept or delta wings.  In some prior flight testing on the Mig-29v3, I found that 40% was better than the stock KF that was varied from root to tip.  With this present build I am going to trim the plane with and without 40% KFs to see if the wing COL changes the measured CG.

The epoxy has set, back to building the latest prototype.

Stephan

Mig-35 Update. This one is the real deal!!

I wanted to update you on the latest skunkworks prototype from RTMS.  Scott and I have been working really hard and building like crazy to finalize this plane.  I took Scott's latest mods, drawings (see his prior posts for details) and plugged them into my drawing program and put some Roll Tide mojo on his mods.  Our plane has slowly morphed from a Mig-29 to the Mig-35.  So I took some designer liberties with Scott's mods and further morphed our hybrid Mig-29 the final step.  I also tweaked the RCP Mig-29v4 here there as I saw needed for fit.

This latest iteration clearly deserves to christened the Mig-35 NAMC.  I have used this naming on previous planes but this plane is truly worthy.   It is the culmination of 7 months of thinking, designing, testing and validating between Scott and I.  The key has been are ability to reproduce flight results on various mods, good or bad.  No fluff here, just hundreds of test flights with quantitative flight data.  Hence our creed:

Puto, Consilium, Test et Convalidandum

Here is the real deal and inspiration of our latest design:

Here is the Mig-29M2 (renamed Mig-35) plans I used as a template in adding the final scale mods:

I'll go over some of the design major changes.  The tail section is where you can see the biggest differences.  The vert stabs now extend all the way to the KFs for a scale appearance.  I also angled the back bottom of the back of the side plate to give a more streamlined scale look.  There still should be plenty of clearance for the elevons at landing.  I am not expecting a change in high alpha flight with loss of surface area of the side plates which act as bottom side vert stabs.  This will be tested of course by Scott and I both.  I had hoped to have this plane finished today, but I ran out of FoamTac, carbon, motors....  Here is a picture of it dry fitted for build verification:

When fitting the canopy, I found that the bottom were it meets the fuselage had a tendency to get moved in creating a coke bottle look--I don't like that look.  Scott and I have also shortened and given the nose a less pointy appearance.   When forming the nose, I start by taping the top to the sides front back to front and tack weld in-between the tape.  I then fill the gaps with strips for strength.  Here is the new nose and the piece I designed to fit insure the canopy doesn't get narrowed:

Here is a picture of the new NAMCv4 nose vs the RCP Mig-29v4:

Here is a picture of the new NAMCv4 nose vs the NAMCv3:

Here are some views, of the tail where I deKardashianed it even further from our last design:

For those of you that have read of my quest for straight line knife edge flight, you may noticed I went with simple full length rudders on this latest build.  Lately, I been having more fun with stall maneuvers which are much easier since my polar moment epiphany (Scott inspired this with his moving the motor forward) and tightening up the center of mass.

I  changed to bottom mounted motor mount reinforcements.  I glue the wing plate to the fuselage.  Then I glue the motor mount to the wing plate only.  I then lift the bottom fuselage piece and glue in the motor reinforcements.  Note: the top photo is a dry fit demonstration of how they fit.  Additionally, these reinforcements make it easier to give the tapered appearance that I like:

The last major change I made was to extend the bottom side LERX along the engine nacelle. This really is an appearance mod and OCD me going crazy with the drawing software.  Here is picture of the extended KF:

Obviously you can tell the weather hasn't been good for me to log in a lot flights.  I've blogged, been drawing and designing modifications, and building.  So no recent crashes and I now have a Mig squadron.  I am running out of parts, that slow boat from China needs to hurry up!  From left to right, Mig-29v4, Mig-35v2 (built for speed with smaller LERX and wing), Mig-35 NAMCv3, and the latest Mig-35 NAMCv4:

Many thanks to my Canuck buddy and fellow aviator veteran Scott for being such a great partner!   I also want to thank Dave Powers and Scott Lott from for allowing us to work on the Mig-29, truly what I believe is the ultimate foamie park jet ever designed.  If you haven't already, visit http://www.rcpowers.com/community/pages/home/ and buy the v4 package.  Stay tuned for more about the RCP Mig-35 NAMC.

Stephan

Mig-35 NAMCv4 Preview

Now that I have figured out my vector drawing software, the modifications are limitless!

After maidening the v3 today, I went straight to Staples to print out the v4.  I'll detail the mods later, but I wanted to post the new vertical stabilizers. I gave them a scale profile and trimmed down the bottom edge of the side plate.  Bonus, the fit was perfect.

The quest continues for the ultimate Mig!

Stephan

Mig-35 NAMCv3 Maiden and Flight report

Nothing like the anticipation of tossing a new plane in the air and hoping for the best.
I have a spreadsheet in which for all my planes I have entered servo travel, dual rates, control surface throw, and even which hole the control rods go in the servo and control horns.  This really helps control the anxiety and preventing thumbing when into the ground from too much throw.

Back to the Mig-35.  Wow.  A brief flight report.  All of the changes had positive benefits in the full flight envelope.  In the past, some of my changes (symmetric foil, downsized LERX and wing for example) benefited only one part of the envelope.

The biggest and most beneficial change on this plane is the lower polar moment of inertia as a result of moving the motor forward an inch.  Bringing the tail plate closer to the wing trailing edge also improved rotation.  With a lower polar moment, I found the plane was easier to rotate in pitch and yaw.  Rudder stall turns were smoother and easier to accomplish.  The plane was also very crisp in the pitch axis.  Perhaps the best way to describe it is that the time from stick input to attitude change in the plane was shorter, i.e. more responsive.

Another maneuver that I have been working on is the climb to a stall and then into a tail slide.  This is easier to accomplish with a tail heavy plane, but not worth the detrimental effect to the rest of the flight envelope--in my opinion.  With this plane I was able to do a couple of slides with much less effort.

I am not a hovering kind of flyer (I prefer to do a prolonged stall and hang it there briefly),  but for a plane to hover it must be well balanced.  Kiko12 on the RCP forum has mastered hovering with a plane of his design.  Dave Powers and I talked last night about plane balance.  Until I had my "polar moment epiphany" after reading Scott's flight report on the Mig-35, I had not given it much thought outside of EPPE.  When I've been revisiting polar moment and its effect, I have been tunneled visioned.  I was addressing ESC and battery placement in the horizontal plane.  Dave was telling me how kiko12 balances his planes in the vertical plane as well.  Dave has been experimenting with platforms to elevate the battery in the fuselage.  The battery bay in the Mig is below the wing plate.  Thinking back on it, the battery in my pattern plane was mounted  even with the center of the wing.

As you guessed, RTMS skunkworks has a new mission.  I am going to optimize battery and ESC positioning both in the horizontal and vertical axes and see how this affects all aspects of the flight envelope.  Goal 1 is shortest possible distance from the front of the battery to the motor mount.  Goal 2 is center the battery with the wing plate.

Stephan

See comment below about this picture

RTMS "Roll Tide Mig Shop" Mig-35 NAMCv3 Build is Complete

Down here at the RTMS I have been watching enviously Scott's flight reports on the latest 'n greatest NAMC evolution of the RCP Mig-29v4.  My build is complete, now I'm waiting on the weather to cooperate.  To summarize the modifications:

1. Motor mount moved 1 inch forward to decrease the polar moment of inertia
2. Trailing edge of wing straightened at root to look more like the Mig-35
3. Side plate shortened 1 inch to bring horizontal stabilizer closer to wing trailing edge
4. Fuselage nose cone shortened to make appearance less "pointy"
5. Inboard vertical rudders in my quest for straight line knife edge flight
6. Downsized elevons to decrease TVAWT and EPPE
7. Shortened ailerons to decrease wing tip stalls

What is that paint scheme?  Well that's what I end up with when I have a bunch of half empty spray paint cans.  Next build will be a base coat of spray paint with a camouflage scheme topcoat.  Acrylic paint is water based like the glue I use for glassing, so the spray paint makes for a nice barrier and doesn't dissolve the glue.

Build & Setup:
1. Carbon 4mm wing main and 3mm leading edges
2. Glassed hinges, vert stabs, side plates, tail plate, elevons and all leading edges
3. TowerPro carbon 9g servos on rudders and ailerons
4. Hitech 82MG servos for the elevons (I have a stock pile of these from when I thought these were necessary, Scott has shown plastic gear servos are fine)
5. Dealmax 2700 motor with Turnigy Plush 40 amp ESC
6. Spoilerons, Flaperons, Rudder brakes, and my favorite mix-ailerons off for high alpha, take off and landing, and high speed grass mowing flybys
7.  16 5/8 oz/471 gms dry and 23 1/4/662 with 2200 battery

Here she is:

Here is a nose to nose comparison:

Here is top view to see the differences in lengths overall and side plate, and motor mount. The plane on the right is stock build Mig-29v4:

The camo Mig-35 NAMCv2 has downsized LERX and wing leading edges which are more scale:

Maiden and flight report to follow as soon as wind and weather breaks.

Stephan

Some thoughts about flying in cooler weather

Hi everyone -

Frost on the field, temperature -2 C/28 F...check

Two Russian park jets ready to rip up the skies...check

Fire lit in the clubhouse wood stove so pilot can get warm...check

So you might be wondering why someone would be crazy enough to fly when the temperature is below freezing... :/?  Well, sometimes I ask myself that, but this time of year where I live it can be some of the best flying weather we have as the winds are calm and the nice cool, dense air helps give good lift and great air for the prop to bite into.

Like very hot weather that some folks are experiencing in the southern hemisphere now and which I wrote a few thoughts on here http://migsrus.blogspot.ca/2014/07/motoresc-performance-in-hot-weather.html , colder weather can also present it's challenges to park jet flying.  I have found that when temperatures are between 5 C/40 F and 25 C/77 F, I don't worry too much about things getting too cool or too hot, but once the temperatures get outside that range, experience has taught me to adjust my flying accordingly.

Now cooler weather flying is probably a bit more of a challenge as not only does the plane have to be treated with care, but the pilot is normally affected more by cold than heat as well... :/

Obviously we don't need to worry too much about ESCs or motors getting too warm, but batteries are another story in my experience.  What I have found is that as the temperature drops below 5C/40F, batteries tend to discharge a little faster and if they are a bit older can have a tendency to discharge more unevenly.  My personal rule of thumb is to not run my batteries down below 3.7 volts per cell.  So to be on the safe side, I shorten my flight times by about 30 seconds to help extend the life of my batteries.

I also try to keep my batteries warm by keeping them in my pocket inside my coat until I am ready to use them or if I have a bunch, I leave them in the little clubhouse where they can stay warmer after I get the fire lit in the wood stove.  Then when I expend them, I also keep them warm so that they don't get too cold as I am continuing to fly, again I am lucky to have a warm clubhouse in which to leave them.  Then when I get them home, I ensure they have warmed up to about room temperature before I put them on the charger.  By following these rules of thumb, I have had good experience now going into my third winter of flying.

Another area to keep an eye on is servos.  I store my planes in the garage, so they are "cold soaked" when I put them in my car and don't get warmed up much on the short drive to the field.  Anytime I have ever stripped a nylon gear servo, it has been cold and I have been too aggressive too soon.  I find that by taking it a bit easy during the first part of the first flight with a plane allows some current to run though the servo and get things warmed up and worked in so that gears, etc are not so brittle and less likely to break/strip.

I think it is also a good idea to give the plane a quick inspection as well, especially if it has been stored in the cold for awhile to ensure all the glue joints are good.  I have found that Foam Tac is a bit more resilient to cold than hot glue.  Sometimes hot glue will pull away from the foam as it gets really cold (ask me how I know this... :/), so it is a good idea just to check all the important joints are still in good shape before flying.  

So what about the pilot?  Well obviously dressing for conditions is important, I find that with all the standing around while flying, my feet can be most susceptible to get cold, so I have good winter boots with thick duffle sock liners that keep my feet toasty.

Hands (ie thumbs) are another story, I guess some of it depends on a person's tolerance to cold and the conditions.  Fortunately when I was flying yesterday, the sun was out and that helped keep my hands warm enough that I had pretty good dexterity for my flights, and then I just put gloves on in between to keep my hands warm. 

 There are lots of options.  I have seen other guys use one of these radio muffs at my field, but since we hand launch our park jets, it might be tough to get your hand back in there quickly enough.  Or even tougher to find someone to come stand in the cold and launch your planes for you... :/

I am a "thumb" flier as opposed to being a "pinch" flier, so having good feel between my thumb and the end of the transmitter sticks is important to me.  I have found using different sticks on my radio has been helpful in the past although the ones I use now have pretty good "sharp" points on the top, so I continue to get good feel even as my thumbs get a little cold. http://hobbyking.com/hobbyking/store/__23762__Alloy_Anti_Slip_TX_Control_Sticks_Short_Futaba_TX_Red_.html

I have also used these big "Turbo Thumb" http://hobbyking.com/hobbyking/store/__12996__TurboThumbs_Super_Big_Futaba_Rocker_1pair_Red.html sticks in cold weather with good success, but don't find them quite as precise a feel as the ones above, but then they have "Turbo" in the name, so they do have that going for them... ;)

In conditions when the sun isn't out and my hands do get cold a little faster, I have flown using military issue flying gloves that I was lucky enough to be able to keep after I retired from the Air Force.

These gloves fit pretty snug and still allow me decent dexterity.  I have also seen folks with cheap wool gloves cut just an inch off the end of the thumb and index finger of the glove so they can still have good dexterity to fly and work switches with bare thumb and finger tip.  I have also seen folks use the glove/mitten combo below, that way you can just flip the mitten part back over your fingers and thumbs between flights to warm them back up.

Of course I am pretty blessed to be able to go into a nice warm clubhouse and warm up every few flights or so if I need to.  Many folks in the northern hemisphere are finished flying (other than those who can fly something indoors) for the year right now and focusing on building, but like I said if you can, it is normally a great time to get out and sneak in a few flights if you take care of your gear and yourself... :)  I always feel a bit more motivated to build something after I have been out on a cool, crisp day ripping up the skies with my plane... :)

Cheers,

Scott

Motor spreadsheet and component weight table link

Hi everyone -

I have been trying to educate myself on Google Drive, so I created a folder accessible through this link https://drive.google.com/folderview?id=0B7TFxGixs_w3a1Z2R2RkUnliVkE&usp=sharing

It contains the spread sheet with the most up to date test data I have compiled on park jet motors and a document that indicates the weights of all the components I used in building my park jets.  On both the spread sheet and the weight document I have included links to all the items should you want to research them more or want to purchase them.

Hope this might be of help to you.  As I am still figuring this all out, if you have problems accessing it, please let me know either by leaving a comment on the blog or sending me an e-mail at migsrus@outlook.com ... :)

Cheers,

Scott

RCP Mig29 V4 NAMCV3 high alpha gone wild...literally!

Hi everyone -

Had just a beautiful day at the field today, tried my hand at some high alpha with my NAMCV3 Mig.  Hopefully you can see when I concentrated on flying rather than yakking or wasn't distracted by the deer that showed up, it flies some pretty amazing high alpha I think... :)

A little extra entertainment when the deer showed up on the runway at 3:15, then I tried my hand at the fancy "behind the back" pass at 3:35, then almost hit myself in the head at 4:44 along with a couple close calls with the ground scattered through the video.  All in all a very fun day, I feel very blessed to live where I do and get a chance to see wildlife in such a beautiful setting and have such great fun with my park jets!  Please enjoy the video... :)

Cheers,

Scott

RCP Mig29 V4 NAMCV2 elevons only

Hi everyone -

Great day of flying at the field today with two awesome planes... :)

I also had a little company towards the end of my flying, a deer family, the doe is giving me the evil eye as the buck walks away keeping a close eye on the fawn which unfortunately is hard to see in the dead grass.  I was probably about 50 ft from them when I took this picture as they walked along the edge of the runway.  Awesome to see, all very healthy and in good shape... :)

Before discussing the NAMCV2 on elevons only, I also reached some pretty neat milestones today -

• 50 total flights now on the NAMCV3;
• 100 flights (102 and counting) on the NAMCV2; and
• 500 total flights (505 and counting) with all my RCP Mig29 V4 variants in total.

So the other day I was at the field and there were a couple of new folks there flying trainer type planes, one had an E-Flite Apprentice S http://www.e-fliterc.com/Products/Default.aspx?ProdID=EFL3100 the other fellow had a Flyzone Sensei http://www.flyzoneplanes.com/airplanes/flza3010/

So in between flights we spent some time shooting the breeze and checking out each other's airplanes as RC pilots will do when one of the guys asked me if a relatively new pilot could fly one of the Migs.  I said yes, a very simple setup with elevons only is a great way to start.  Then I realized, I had never flown any of my NAMC Migs elevons only to see how the smaller elevons managed.

So when I went to the field today, I turned off the rudders and ailerons on my NAMCV2 (the all blue one in the picture above), cranked the aileron input up to 100% in my elevon mix and off I went.  I wanted to fly the Mig elevons only from a standpoint of how it would handle if I was a beginner (which I still feel like depending on the day... :/)

I flew seven full flights with elevons only and was very impressed with how it handled.  It turns very easily and without hesitation, not as much control input actually required as with other elevons only planes I have flown because the surfaces are more efficient and cause less drag and turbulence when deflected than larger stock surfaces.  Rolls were a bit more lethargic than I am used to with elevons and ailerons working together, but still very good rates for where a beginner would want to be.

So as I was flying, I tried to remember back to my first park jet, an elevons only RCP F35 V2.  Not the best picture in the world, but hopefully you can see that those elevons are pretty huge... :/  One of the first things Stephan and I both wanted to look at with our park jets when we got together was how scaling down the control surfaces, primarily ailerons and elevons would help with our plane's handling as we both found that the "control surface creep" that was happening in a few park jets was impacting how they flew.

So back to when I first started flying this F35.  I remember often getting into trouble being too slow in a turn, cranking on too much control (something I think almost all beginners do at some point) and my plane would just park itself in the air as those big elevons acted like air brakes, made the plane stall, do funky things, all of which caused me to try and over control even further, leading to...well not the best of situations.

So I got looking at the trainer planes these two fellows were flying as they are good basic trainers for learning how to fly.  Granted they are a scale high wing type plane, but their control surfaces are not huge, rather more in line with what they would be on a real version of a plane.  Enough that a person can fly them around fairly gently, or have some fun with basic aerobatics as skills progress, something any beginner plane should have I think.  So why would we not use the same thing on park jets?  Smaller, more scale size elevons for elevons only that allow for precise control without as much tendency to TV stall makes a lot of sense to me.  

I remember many a time having my heart race when I watched planes park themselves in the air because of very large control surfaces that suddenly acted as "un-control surfaces" making my life very difficult and often leading to my day being shortened due to a crash.

Obviously Stephan and I are big fans of downsized, more scale like elevons and ailerons, we like our rudders big, but prefer smaller more efficient elevons and ailerons as they are more efficient and allow for more precise control of our planes.  We both are huge fans of the fixed horizontal stabilizer and hinged elevons on the Mig29 V4 which is also on the RCP trainer the Su34 V4.  I am very happy to see this on the trainer.  I think this fixed horizontal stabilizer setup is the biggest breakthrough yet on the two of the V4 planes.  I have also tried it on an FRC Su35 MK2 and will use it on every plane I build from now on.  The stability it adds coupled with how it reduces the size of the moving surface thereby reducing drag and turbulence associated with the moving surface is a simple yet amazing improvement in the world of park jets.

So yes, we do push our planes hard and are not beginners, but I think the philosophy of having enough control so that you don't over control is very beneficial when learning.  I think smaller, more scale size elevons on an elevons only plane is a very good way to go.  Just my humble opinion backed up by what I saw today with the best elevons only flying experience I have had.

So I guess my message is, stop "control surface creep", like everything in life, moderation is a good thing and bigger is not always better when it comes to control surfaces... :)

Cheers,

Scott

RCP Mig29 V4 NAMCV3 Dialed in

Hi everyone -

Another great day of testing and "dialing in" at the field yesterday.

I had my oldest plane, the RCP F18 V3 out to field test another motor, the YUSHOP66 2212/6 2700 Kv motor from a vendor on eBay http://www.ebay.com/itm/321227178111  You can read more about this motor and the test results both at the field and on the bench here http://migsrus.blogspot.ca/2014/11/yushop66-a22126s-2700-kv-park-jet-motor.html

It was a good day to do some final "dialing in" on my RCP Mig29 V4 NAMCV3 (which I will call the V3 for the rest of this post for simplicity's sake).  I had a myriad of conditions from dead calm to the odd bit of swirling wind up to about 10 mph.

This plane handles amazing in the wind.  Of course it is about 15% heavier than the other Migs that I fly which does help, but the wind had almost no impact whatsoever on it's handling and stability.  I was very impressed, no wobbles, tail wagging, just solid and true tracking through the wind, especially in turns.

I managed as well to better assess it's slow speed handling and high alpha performance.  Normally I have had real challenges getting planes with the NTM Prop Drive setup to stay consistently stable in high alpha.  The bigger heavier motor and extra torque roll affect of this setup can make high alpha a bit more of a challenge for me than with lighter setups.  This plane is very stable in high alpha, although it is more susceptible to wanting to pull left due to prop wash and torque roll.  There is some very detailed information in this post http://migsrus.blogspot.ca/2014/08/mig29-v4m3e3-hi-alpha-testing.html about prop wash, prop torque and P factor and their impact on a plane's high alpha performance.

Probably due to the volume of air and the aggressive bite inherent with the 6x4 APC prop compared to the 6x3 EMP prop, in order to fly in a straight line with a high AOA (angle of attack), constant right rudder input is required, otherwise the nose will just continue to drift left.

I also found that because the center of mass on this plane is so much closer to the center of gravity and it is a larger quantity of mass (3.2 oz more than most of my Migs), rudder response is much greater, so I softened up the rudder with more expo and also really focussed on keeping rudder input as smooth as possible.

So again, this was very interesting to me as normal rule of thumb from previous experience was that for good high alpha stability on most planes, the largest percentage of mass (the battery) needed to be fairly far forward of CG for good stability in high alpha.  This plane with it's centers of mass, gravity and thrust all being much closer together seems to go against that theory.

Granted, the battery is ahead of the CG, but when I compare it to my F18 V3 with which I have flown considerable high alpha, the battery on this Mig is much closer to the CG than on the F18 and remains very stable.  I won't get into another round of measurements as I have in previous posts, suffice to say that other than the increased effects of prop wash and more sensitive rudder, this plane does high alpha very well even with a heavy, higher torque motor like the NTM Prop Drive.

As I have written in a previous post when I did a fly off between the NAMCV2 and V3 http://migsrus.blogspot.ca/2014/10/rcp-mig29-v4-namcv2-and-v3-flyoff.html, the V3 requires less control input to generate the same rate of roll, pitch and yaw.

So now that I have 41 flights on the V3 and have it dialed in where I like it, I got out the ruler and did some comparison.  I will only compare the throws on the ailerons and elevons, I keep the throws at 100% on the rudders on all my planes just because due to phenomena discussed in the link above about high alpha testing, I like to have maximum throws on my rudders.

I will express my settings in inches of travel rather than percentage of throws for the ailerons and elevons as your servos and transmitter are probably different than mine.  I have also posted the travel for my NAMCV2 Mig for comparison purposes.  I should caveat that I prefer to fly my planes a bit more scale, so keep my throws fairly low as I don't need my planes to tumble loop or do rifle bullet type rolls.  I do however like to have a bit of extra "emergency throw" in the elevator to help avoid sudden impact with immovable objects... :/

NAMCV2

Elevator travel -  2.5" in each direction for a total of 5" travel.

 Aileron travel - 5/8" in each direction for a total of 1 and 1/4" travel.

Spoileron deflection for high alpha - 5/8".

NAMCV3

Elevator travel - 2" in each direction for a total of 4" travel.

Aileron travel - 1/2" in each direction for a total of 1" travel.

Spoileron deflection for high alpha - 1/2".

So I am very pleased with these settings and the results when compared to the V2.  By having much better balance with the V3 and the centers of mass, thrust and gravity so much closer together, I get the same handling performance with 25% less control surface travel.  So why is this important to me?  Well as I have said many times throughout all of the experiments that Stephan and I have done in downsizing control surfaces from stock, smaller surfaces travelling less distance make for a much smoother flying and more stable and precise plane.  

With the laws of physics working much harder in our favor, it means the surfaces don't have to work as hard.  Anytime I can have less deflection on a control surface to do the same job I will take it as it means less drag and therefore less turbulence.  This makes the control surfaces perform more efficiently and makes for a smoother and "quieter" flying plane from a standpoint of stability.

So I continue to be very excited by how well this latest NAMC version of the Mig flies.  Stephan hopefully should have his built and flying shortly, so I'm very excited to hear what he thinks and what his findings are.  It is through repeatable results and thorough, consistent testing that we have found the best information and validation of our modifications.

In a previous post I mentioned I was thinking of going back to the lighter Focal Price setup on this plane, but I have decided to "man up" and keep this big motor in this plane as it pushes my skills a little harder than the lighter setup.  Instead I will build another Mig (big surprise there...hello, my name is Scott and I am a Migaholic... :/) with a lighter setup, less reinforcement, etc.  I will probably wait until after Stephan has built and tested his in the event there might be other mods we could test/try, but I have a feeling that although the work is never done, this V3 is the culmination of a lot of great ideas and testing that we have worked towards over the last six months since this plane was released, so I'm not sure what else could be done.

Cheers,

Scott

RCP Mig29 V4 NAMCV3 Speed fun... :)

Hi everyone -

Back out at the field yesterday with my two favorite Russian park jets.

Since making the repair on the motor mount on the Mig, I also took a look through my motor bin and found an NTM with smoother bearings than the first motor and also put on a brand new balanced prop, so I wanted to do another round of speed trials on both 3S and 4S.

So here is some video footage of it.

Oops, sorry, wrong video...but thought that would get you in the mood for some speed... ;)

Here is the real video, first part is on 3S, second on 4S.  I apologize that due to the speed, the fact it needs a lot more room in which to fly because it is so fast and the bright sky that it washes out occasionally, but hopefully you get a sense of darn fast this little beauty is... :)

So with a good solid motor mount, smoother running motor and brand new balanced prop, I actually squeezed some more speed out of it... :) 

On 3S, I managed 4 good speed runs of 99/97/96 and 93 mph, about a 2 mph improvement in top speed over the first set of trials I did.

On 4S, I managed 4 speed runs of 117/111/105 and 102 mph, again about a 2 mph improvement in top speed over the first set of trials I did.

I am really so pleased with how well this plane flies, I haven't flown a plane with that much speed before, so it does take some serious concentration as you might see on the very last speed run on 4S, I twitched the stick just a bit to the left before making the right turn and it was headed for the trees at a rather rapid rate of knots!

Awhile back, Stephan and I had talked about building a plane light but strong that would still be able to take the NTM Prop Drive motor, but also fly well with the Focal Price motor.  I think that even though I increased the weight with more carbon reinforcement and one set of metal gear servos over how I normally build, because I reduced the size of the plane, the two balanced out.  That and experimenting with thinning my paint down helped me keep the weight of the paint job down.  

So this makes this plane pretty flexible being able to swap power systems and have the airframe easily handle either without sacrificing overall performance.  In all honesty I will probably go back to the lighter FP setup as I am so used to that, it is a bit more relaxing flying.  But it is nice to know that if I am really feeling feisty I can do a 10 minute motor and ESC change and really tear up the sky... :)

So next up is another FRC Su35 MK2 with a fairly ambitious modification plan, then we shall see where we go from there.  Maybe I'll do something different and build another Mig... :/

Cheers,

Scott

YUSHOP66 A2212/6S 2700 Kv Park Jet motor updated with new results 10 Nov

Hi everyone -

A couple months ago when I was searching around for alternatives to the Focal Price 2700 Kv motor http://www.focalprice.com/YO090X/A2212_2200KV_Outrunner_Brushless_Motor_for_Airplane.html which at the writing of this post is still out of stock (been that way for about three months now), Rob Davis one of our followers told me about this motor from an ebay vendor in China http://www.ebay.com/itm/321227178111

Here is a picture of it with the bullet connectors, X motor mount and prop installed.

The dimensions and weight of this motor are exactly the same as the Focal Price and Deal Extreme 2700 Kv motors I have already tested.  It weighs 66 gr/2.3 oz with all connectors and prop installed.

Just like the FP and DX motors, you need to provide your own bullet connectors and a prop collet, the one that comes with it is the same quality as the one that comes with the Focal Price motor so I replaced it with a better one.  Shipping with this vendor is free, but it was slower than with Deal Extreme, the package was shipped 08 Oct 2014 and I received it 07 Nov 2014 on the west coast of Canada.  It may very well take longer depending on where you live.

At $10.99 it is a bit cheaper ($1.30 cheaper) than the FP or DX motors, but if you buy 3 motors from DX, the price is the same per unit $10.99 per motor.  I think this vendor buys up 25-30 motors at a time from somewhere and then resells them.

After a break in period, I retested the motor and received more realistic results, updated on 10 Nov.

This test was done with a 6x3 EMP prop, Turnigy plush 40A ESC, 2200 3S 40C discharge battery.

At 50% throttle, the motor drew 12.7 amps and produced 150.1 watts and 517 gr/18.2 oz of thrust.

At 100% throttle, the motor drew 35.7 amps and produced 421.8 watts and 1033 gr/36.4 oz of thrust.

So definitely a 40A ESC is needed with this motor like it is with the FP and DX motors.  Here is a video of some field testing I did with this motor in my RCP F18 V3

Thanks again to Rob Davis for finding the motor for us, it is definitely the same motor as the Focal Price and Deal Extreme 2212/6 2700 Kv motors and another source to purchase from depending on availability.

Cheers,

Scott