FMS P-51D Mustang 57" Wingspan EPO
This is my attempt at creating a build/mod/information blog on the FMS 57" WS EPO foam P-51 D Mustang, mainly concentrating on Version 3, which is what I have, however I will try to include Version 4 specs as they come available, which is being released as this is written. This is going to be a mix of items from the Thread that was started in August 2009 https://www.rcgroups.com/forums/show....php?t=1092043 that is now well over 202 plus pages and over 3000 plus posts!!! I will continue to add as time allows a lot of information that I have been gathering since the first post up and too the last post (which is forever growing) from various individuals. I am most grateful to these folks for their knowledge and expertise in so many facets of RC aircraft, and if something you have posted is not mentioned or seen here do not take it personal as this is a compilation of article/mods/thoughts & feelings that I feel are important to me and worth mentioning. Hopefully someone will find this helpful and answer questions one might have without having to search endlessly without finding an answer!
Photo courtesy of Carlos (Guapoman2000) and the Orlando RC Group
FMS P-51 D Mustang Build Notes & Modifications
Version 1: 3S-Setup Prototype Version: 1800mAh, 11.1V Lipo / 30A ESC and 770KV motor & fixed gear, delivery by beginning of September 2009.
Version 2: 4S-Setup 2200mAh, 14.8V Lipo / 45A ESC and 540KV motor & fixed gear (Landing Gear IS retractable with blocking removed & servos installed); no flaps; no retract servos; delivery by beginning of October 2009
Version 3: 4S-Setup 2200mAh, 14.8V Lipo / 40A ESC and 600KV motor; retractable gear (working Retracts are controlled by one 17g-servo each) & flaps (flaps are prepared and hinged, just add servos); strengthened wing (Carbon Fiber spar reinforced wing); Servos are 2 x 9g for the ailerons, 2 x 9g for flaps, 1 x 9g for the elevator, 1 x 9g for the rudder (non-retractable tailwheel connects via rod into the rudder), 1 x 9g for the scale steerable tailwheel (can be made to retract by adding servo); delivery by mid November 2009.
Version 4: 4S-Setup 3200mAh, 14.8V Lipo / 50A ESC with Separate BEC and 600KV motor; non-retractable steerable tailwheel; delivery beginning February 2010 (more specs to come)
NOTE: If you order V3, and you are unsure about which version of tailwheel you are ordering, because photos on some Vendors product description show both tailwheel versions for example, the servo count is the key because the scale (retractable) tailwheel has its own servo for steering! So, V3 with scale (retractable) tailwheel has 2 landing gear retract servos, 2 flap servos, 2 aileron servos, 1 elevator servo, 1 rudder servo and 1 tailwheel steering servo, 9 in total. If V3 has 8 servos, it has the steerable non-retractable tailwheel which connects via rod into the rudder, which is also is in the wrong non-scale location. The retractable tailwheel is in the right scale location, is steerable and retractable “if” you add a servo. Note that some retract tailwheels have a block that was installed by the manufacture that prevents it from being able to retract, making it a fixed tailwheel. This block is easily removed, and is all that prevents the retract from working in addition to adding servo. If you have the new tailwheel and want the scale one, order it. FMS did not change the shape of the fuselage EPO moldings, they just put a large EPO plug in the spot where the scale tailwheel retract is housed in the fuselage. You have to cut that out and install the retractable tailwheel.
Main Specifications Version 3
Style NO: FMS008
Material: Durable EPO
Wingspan: 57” (1450mm)
Length: 49” (1240mm)
Weight: oz. (1600g)
Servos: 2 - 17g Main Landing Gear; 6/7 - 9g (2-ailerons, 2-flaps, 1-elevator, 1-rudder, 1-steerable tailwheel) "See Above Note concerning tailwheel variations" All Servos are Installed
Battery: G&C 14.8V/2200mAh/20C Li-poly battery
ESC: G&C 40A Brushless Installed
Motor: G&C 3648-600KV Outrunner Brushless (15.0 V max, 55 A max) Installed
Propeller: 4 Blade Propeller With 3.5" Plastic Spinner and 2 blade propeller with spinner (Included)
Recommended control throws: (according to Hobby Lobby’s Instruction Manual http://s3.amazonaws.com/hobbylobbypdf/erc5100-inst.pdf )
Rudder -1” in each direction
Elevator- 3/4" Up and Down
Aileron- 7/8” Up and Down
Center of Gravity:
Center of Gravity is located at the two circles (at exactly 235 mm from the wing root, just as the FMS manual describes) in the foam just under the black stickers on top of the wing, which if you look at it the Carbon Fiber spar goes right through the middle of this circle. The Hobby Lobby Manual (Item #22) states that on the bottom of the fuselage, measure back 2-1/4” to 2-3/4” from notch at the front of the wing root is where COG is located.
Notes from the main build thread:
Tom Hunt: Stability in the pitch axis was fine on mine with the CG in the middle of the circles.
Lenop: I made sure the COG stayed correct with the Retractable tailwheel setup. But with the stock battery in the default battery bay, I had to made sure the battery was not pushed all the way to the front of the bay in order to get the proper COG.
Electronics (ESC, UBEC, Battery, Servos):
This IS the one issue that many folks have had problems with…Electronics! This seems to be an issue with quality electronics versus cheap made electronics…you know the old adage that you get what you pay for. Some folks have had NO issues and others have had all kinds of issues. Electronics is an issue of personal preference as most quality electronics are more or less the same in as far as quality goes, so in this area to “each his own” so to speak. So I am not going to get into one brand is better than this brand of electronics as it becomes a version of “my dogs better than your dog” scenario. I will say that IF I were to purchase the FMS P-51 again that I would buy the airframe only version, NOT the RTF version! Why spend money for all the electronic hardware to end up replacing most if not ALL of the electronics due to the fact that they are NOT dependable electronics! I’d rather have peace of mind knowing that my electronics are not going to fail than to wonder when they will fail.
The consensus IS that prior to a maiden flight that a quality UBEC (Universal Battery Eliminator Circuit) should be installed at minimum IF one is going to keep the stock ESC! The stock ESC in and of itself is a candidate for replacement as well as several folks have had issues! Version 3 comes with a G&C 40A Brushless ESC Installed. One must consider the fact that in stock form there are as many as 8 to 9 (depending if you have a retractable tailwheel) servos, with the main landing gear servos of 17g each, with the remainder being 9g each receiving power through the stock ESC as there is NO external power supply! Bungymania’s review of this aircraft with the stock G&C 600KV motor (rated 15.0V Max, 55 A Max), with the stock 14X8X4 blade propeller, shows this combination pulling static measurements of 44.2 Amps, 14.89 Volts, 658 Watts, and 6712 RPMs. Add in a servo rate reducer for the landing gear/tailwheel retracts and this just adds to the stock ESC possibly exceeding it’s amp rating ensuing in disastrous results.
With a UBEC, if the stock ESC gives up the smoke, at least you will still have control of the aircraft versus loosing ALL control eventually coming down fast and hard into mother earth! The main point is that you shouldn't rely on the stock ESC's internal BEC to provide power to the receiver along with 8 to 9 servo's unless you are prepared to face the consequences of a possible inflight brownout.
Notes from the main build thread:
Topkits: Linked my Watt's up and at full throttle ESC draws 46 A at 15.2 V which gives exactly 700 W. All this with the standard 4-blade prop. As Beltpilot already noted I think it's a bit risky to fly with this stock ESC.
Topkits: Post #1296 I guess that with the original V1 with just aileron rudder and elevator control the ESC was sufficient. With the V3 you have at least 9 servos working (up to 10 with tail retract) and this may create an overload of the ESC even if the ESC has been upgraded from a 30A with V1 to a 45A with V2, and a 40A with V3. For safety reasons I installed a 3A UBEC in my Mustang.
Tom Hunt: I did a bit of testing with the supplied motor and the 4 blade prop. After one short run with the supplied ESC, it is a non-starter.
Tommy D: Regarding the ESC. Even if it were to unload a total of 10% in the air your still pushing it IMO. Also if the ESC is buried in either the top or bottom channel in the nose it's not going to get all that much air flow over it. That said, if you need hurricane force winds to keep a ESC cool then your doing something wrong! No doubt the 60A ESC is a much better choice. I do have some concerns flying a model this size with a "cheap" Chinese ESC or BEC.
Wolw: Post #1167 Regarding BEC on ESC's. I Only use the built in BEC switching or not on 3S or less setups. Better to let the ESC only deal with managing throttle. I also use the larger 7.5A BEC on setups with large and/or digital servos. Better safe than sorry!
Wolw: Post #1297 Amp rating of the ESC has nothing to do with the built in BEC circuit. The linear BEC circuit will still get hot when you put load on it and it has to burn the excess voltage (nom 14.8V down to 5V) as heat. A higher amp ESC might give you some headroom as the surrounding PCB wont get as hot. A UBEC is the way to go!
Wolw: Post #1879 According to Dimension Engineering...It is very common for speed controls to have BECs rated at 2 or 3A. However, what the manufacturers do not tell you is that this rating is only true for an input voltage of 6V. The BEC on your speed control is what engineers call a 'linear voltage regulator'. It works by burning up excess voltage and turning it into heat. The higher the input voltage, the more heat gets produced. If there is too much heat, then the BEC will either fry, or shut down! The result of this is that in real world situations, if you are running a 3S lithium battery pack, your ESC's BEC will only be able to provide about 0.5A before it overheats. At 4S, most ESC manufacturers don't recommend you use the BEC at all, or at best power two small servos.
Guapoman2000: Post #1161 I suspect that this is a linear BEC because when I connected my Flight Battery at the field during my attempts to maiden for the very first time, the ESC and nothing seemed to come on. I disconnected the flaps that are in constant load (stock configuration) then, all was well. You are correct on your thoughts about too many servos and a non-switch mode ESC.
Guapoman2000: Post #1280 I finally installed the Castle Creations BEC Pro in parallel with the Stock ESC. The JR Sport Aileron Extension is connected between the ESC and Receiver and at this extension is where I take out the RED middle wire instead of messing with the ESC harness, thereby disabling the on-board BEC.
Guapoman2000: Post #1284 The CC Pro BEC at it's lowest input Voltage of 16 Volts can output it's highest Current at 15-Amperes so, I am very confident that it can handle the total contingent of 9 servos that my model has on-board. It's when you fly with more Voltage that I would be worried about as the current goes down. Therefore, under load the CC Pro BEC would handle very well.
Guapoman2000: Post #3063 Mine crashed in it's third flight with no control using the Stock 40-AMP ESC, a good one my I add. However, due to the number of servos the BEC must have gone into a thermal shut down and my Spektrum AR7000 experienced a brown-out (lack of input Voltage) causing the model to Crash. Now she fly's with the Castle Creations BEC PRO and all is perfect!
LiCobra: Post#1286 Let me ask another BEC question....do servos that are not active such as flaps or retracts when flying draw the same amount of power as aileron, elevator and rudder?
Tom Hunt: Post #1287 The LG servo current in either the up or down lock condition should not be any higher than "idle" current as any air-load will not be transferred to the pushrod. A flap servo, even when the flap is in the stowed condition will still see something higher than idle current because the air-load will be trying to back-drive the servo through the pushrod. This is usually not very high and probably no more than 2-3x idle current on most models.
LiCobra: Post #1297 Tom if a BEC has a servo rating of 8 servos like the DE Sport BEC, do they mean 8 active or a combination of active and idle...as with my 3 retract servos?
Tom Hunt: Post #1298 I have never seen a clear standard for determining how many servos/current any particular BEC can handle and as Carlos explained after talking to castle, it is truly hard to quantify.... but safe to say they probably mean all 8 servos moving at the same time loaded to nearly their highest current draw (torque) without stalling. Making a BEC that would survive 8 stalled servos would be meaningless as the model would not be in the air very long!
Tom Hunt: Post #2100 Most ESC manufacturers will tell you it is MUCH better to extend the motor wires than the battery wires (voltage spike problem).
The stock battery is a G&C 14.8V/2200mAh/20C Li-poly with Deans Connector, and according to Guapoman2000 the stock 4-Cell tips the digital scale at just a little over 8 ounces.
There is a wide selection of potential battery’s for this aircraft with the only limitations being their shape and weight from the various manufactures. Bungymania’s review states that a suitable battery must weigh between 15% (337G) and 20% (449g) of the flight weight of their FMS P-51D (2246g). And that beyond that weight, the heavier the battery is, the more damage to the flight characteristics of the aircraft. Remember, “personal favorite” in as far as a battery does not count when someone melts the pack or flies for too long.
Notes from the main build thread:
Guapoman2000: Post #1128 I flew both maiden flights with the STOCK 4-Cell, 2200mAH, 20C discharge Li-poly.
MYC: Just to clarify for my own self then, the battery for me is NOT fixed as I can use what I want (within reason) BUT 40 amps should be my target. Finally, I am not trying to equal the performance of the two-bladed prop, I am trying to get the maximum performance out of the four-bladed prop.
Tom Hunt: When I say the battery is fixed, I mean the cell count. I always look for the "best" battery in that cell count for the current I want to draw. The G&C battery is still a dog at 40amps despite the fact that it is well within the 20c rating. Just means that they are a bit "liberal" with their C-rating. I have always told people I can hold my breath for 40 minutes, but I can only do it once! I can draw 40amps out of that battery pack... but I can only do it once!
Kydawg1: FYI - this plane rocks on a 2200 4S..... my personal favorite. It still flies great with my Rhino 3700 or my XPS 3200. Try them all, this bird is versatile for sure.
Guapomann2000: Post #1139 The Stock 4-Cell, 2200mAH, 20C discharge, Li-POLY seems adequate enough for a good 6 minute flight with ample reserve for go around in case your approach for landing is not what you like.
Tom Hunt: I determined quickly that the supplied battery was not going to hack it. I substituted a 4 cell TP 2250 45C battery. Not only was the current way above the limit of the controller (49amps at 6500 RPM), the controller acted a bit "funny". When I got to about half throttle stick, the wattmeter was recording a current value in the low 20's. as I just added one "click" more, the current jumped into the 30's without a noticeable increase in RPM. I continued on to get up to max throttle but for only a second or two. I then put the motor on an ICE 100lite ESC to record data all the way up the throttle range. This showed that the motor was not at fault for the "jump". The throttle/current progression was nice and smooth. I also noticed that the RPM and current was actually higher on the same pack (probably due to the lower resistance of the controller and heavier gauge wire.
Motor; Voltage; Current; Watts; RPM = G&C 3648; 14.45V; 41.1A; 593.895W; 6153 RPM
Kahloq: You can easily get better performance than the stock motor by running a higher cell battery without changing anything else, as long as the ESC can keep up. The only time really that you get better performance using a higher cell count is if the motors in question are similar in KV rating, and one just happens to be able to support higher cell counts where the other one doesn’t (or is questionable) while still using the same propeller.
Servos are again an issue of personal preference in as far as size or brand for that matter. One MUST consider size, weight, torque in as far as replacement servos!
Notes from the main build thread:
Tom Hunt: Post #1325 I have ripped out both the elevator and rudder servos and because of a stripped gear on my tailwheel retract servo, I have made a new servo mounting plate and installed 2 new and one older HI-Tec HS-81 servos. I also cleaned up the pushrod installation. Additionally, since I was into hacking up foam this morning, I got rid of the dual servo elevator pushrods and installed a 3/32" diameter elevator joiner between the two elevators. The wood pushrod is for the TW retract. I just did not have a wire (with 2-56 threaded end) long enough to reach!
Guapoman2000: Post #1137 I have found the retract servos that come with the FMS model with retracts very adequate as you have a good size servo (mini size) for each main gear.
Guapoman2000: Post #1184 You need to stick to mini servos that have at least 45 - 50 in-oz.
MYC: As for the controls, watch the elevator pushrods. In the stock elevator servo location, they bind pretty bad. I moved the servo more toward the middle of the fuse which helped a bit, pulled the tubes away from fuse near the appendage and finally swapped the servo for one of my favorite HXT-900's.
Attention! Check your Stock motor to ensure that the output shaft HAS the C-Clip lock ring INSTALLED on the shaft! Failure to do so could result in the output shaft coming out of the motor during flight or bench testing resulting in damage to your aircraft or injury! This IS an issue many folks have found concerning the stock motor.
I have not heard many reviews of the stock G&C 540KV motor that was offered in V2, except that it was not sufficient in performance which resulted in V3 being upgraded to a 600KV motor. The G&C 600KV is the stock motor being offered in V3. The 600 to 650KV motors seem to be the average KV rating of those opting to use their motor of choice over the stock 600KV motor, at least those utilizing the 4 blade propeller. As far as the stock G&C 600KV motor, some have found their motor to be junk while others have found it to be perfectly satisfactory. The 600KV appears to perform satisfactory delivering scale speeds, with plenty of power as well according to most reviews. If one is looking for more performance/speed versus aesthetics, one can always install the 2 blade propeller (most of my review ONLY includes the 4 blade propeller, NOT the 2 blade propeller as I personally will only utilize the 4 blade propeller). Bungymania's review states the following, "By replacing the engine with a more powerful one wins 10% but still it raises consumption and reduces the duration of flight." It also states, "the stock propulsion base is effective."
Notes from the main build thread:
Bernard: Post #1260 Please check also your motor, on mine the c-clip was not in the shaft groove. The external motor part can get out with the propeller!
MYC Post #1264 My Hub is loose at the motor bell too!
Guapoman2000: Post #1270 My last item / issue is the lack of a Donut Collar for the frontal bell of the motor as this device slides on the output shaft of the motor and using a set screw it is allowed to ride very closely to the C-Lock Ring that holds the Outrunner motor! Well, if you look at the pictures the factory did not install one!
MYC: Anyway, Ran the motor up. It really is junk. It has a annoying vibration that I first thought was due to the prop but after some balancing the vibe remained so I ran the motor by itself and the shaft wobbles.
JBC: I since discovered bigger KV doesn't necessarily mean more/less power, it's more to do with finding the balance between what battery size you want to run, how much current you want to draw and what flight performance you want(please somebody correct me if I sound like a bit of a knob at any stage ). I have an electrical background so some of this make sense to me, being a bit of a newbie though I'm on a steep learning curve like yourself regarding the practical application. A bigger motor using a bigger battery will always draw less current for the same performance(to an extent)but finding the right combination...now that's the million dollar question!
Guapoman2000: Any higher KV motor will have less torque and most of the energy going to that higher KV motor will be transferred into heat and not mechanical energy to swing that 4 Blade Propeller. The higher KV, the less Torque and vise-a-versa so, depending on the diameter size of the propeller, usually even a lower KV would be better to keep the efficiency UP to it's maximum as the motor will have even more Torque and to spin the propeller for respectable airspeed you just go UP in Voltage.
ATTENTION! Ensure that the Propeller Securing Nut IS torqued down tight! Failure to do so can result in injury and your aircraft sustaining severe damage! Several folks have had this to happen during bench testing and in flight!
The STOCK 14 X 8 X 4 Blade propeller assembly is a whopper of 14 inches diameter! Albeit it is 3 inches short over scale which would be a 17 inch propeller, and Tom Hunt says it best, “Multi-blade props are for “looks” not performance“. The stock 4 blade propeller will allow for very good thrust. The consensus is anyone looking for additional speed should consider a 3 or 2 blade propeller. With that said, I am not going to delve into 3 or 2 blade propellers as I never plan to utilize them as I am after scale looks and speed, not go fast turn left.
Notes from the main build thread:
Kydawg1: I have found 14x8 - 14x12 to be awesome on this bird. Still greater than 1:1....been flying this plane for about 2 months...it does not get old.
Tom Hunt: The scale 4 blade prop for a 1/7.8 scale FMS Mustang would be 17" (11'2" full scale Mustang). If you want to swing multi-blade props of any size larger than the 2 blade you need a real low KV motor. The trouble with doing that in a "smallish" motor like the G&C is that the wire (windings) size gets too small and cannot carry any current. To swing BIG props you need BIG motors... simple as that. Big motors will have lower KV without the small wire size. To keep the current down, you need to reduce the motor rpm, which will reduce the speed of your model.
MYC: Seriously though, I'm still not 100% on board with the mutually exclusive assessment. This plane is big and as is way under-loaded in stock trim. Why can't we go bigger on the motor to get this 4-bladed prop moving to it's max efficiency? Forgetting the "garbage" motor that comes in this thing, there has to be a motor/battery combo that will spin this prop to its peak performance. My real issue is what RPM is that? I 100% agree with you that multi-bladed props are less efficient due the wash of the previous blade disturbing the air over the following one but I am not looking to race. I just want every bit of power that this prop has to offer.
John Hunt: Given an infinite number of motors and props, I can ALWAYS find a 2 blade prop that will out perform (speed, climb and cruise) than a multi-blade prop. It really has nothing to do with prop efficiency between a 2 blade and 3 or more, it has to do with Reynolds number (the fact you cannot scale air). To make a multi-blade prop absorb the same power at the same RPM as a two bladder it must be smaller in diameter and have less blade area. This makes the local Reynolds number on the blade poorer. Once you "fix" the prop and the cell count... such as the FMS P-51, then it's just a matter of finding a motor that will swing that prop to the RPM that you feel "comfortable" flying the model without draining the "tank" in a hurry. I do not design my own model systems to draw much more than 40 amps in this class model. Losses in 'electrical" performance is a "square" function of the current. Drop the current just a little and everyone is happier.... motor ESC and battery... they seem to last a lot longer too!
Guapoman2000: Post #1097 When Gerry retrieved the Propeller assembly (intact) with the spinner, he was shocked to see that the backing hole had a mold for a NUT. He was totally against me from placing this assembly back on the propeller adapter as I was missing the NUT. I told him that this plastic back plate was made for dual purpose, one for propeller adapter in direct drive and perhaps a large gearbox that could use that NUT molding. As it turns out and for good measure, I asked Gerry for some double sticky tape and tore off two thin rectangular pieces and placed both at the face of the Prop adapter and then, I went ahead and slid the propeller / spinner assembly onto it. It took a good amount of torque down and also had to use a straight slot screw-driver to hold the Propeller adapter from any spin action to get that assembly torqued down good! The double sticky tape work GREAT as it did not allow the smooth Plastic Propeller Spinner back plate from spinning as I torqued down the securing NUT. It could have been a combination of the two but, primary my fault for not making sure the NUT was torque with sufficient force.
LiCobra: Post #1127 On my first static motor test for watts and rpm my prop came loose also...I'm thinking of replacing the spinner/nut with double nuts of the conventional type. I believe that both (FMS & Hobby Lobby) versions come with the scale 4-Blade Propeller assembly consisting of a Spinner Back Plate made of plastic and individual propeller blades that are secured by two machine screws. Each Propeller side gets screwed into the Spinner back plate with two machine screws each (Supplied). This means that if your model experiences a Propeller strike on the ground or with something that does not move the chances are that the Propeller blade "and" most importantly the spinner back plate might get damaged.
Tommy D: I installed the FMS 13x9 <looked like a sport/glow style prop> and found a shim was needed. By shim I mean to say if you use the stock Collette/nut adapter it will bottom out. So I double nutted mine.
Kahloq: The load on the motor is proportional to the pitch as well as diameter. So, if you up the pitch, u may be forced to lower the diameter when running higher cell counts. In the end, your not reducing the amp draw much since u got to run a higher pitch (if you are trying to match performance), but are adding a lot of battery weight.
Well, I think that those of us that have this aircraft will agree, it IS very big and it demands attention! Most from a distance do not even realize that it is a foamie until they see it up close even. EPO IS not like other foams and you do not have all of the unsightly markings that other forms of foam have in my opinion. They say EPO builds with regular CA, however I utilize foam safe CA to pacify myself! EPO IS durable and lightweight and with proper preparation will hold paint very well. I did find on my Mustang that the fuselage, which is two pieces molded separately and glued together at the factory, had several areas along the entire length of the fuselage inside and out that I felt needed to be re-glued, again to pacify myself!
Notes from the main build thread:
Tom Hunt: FMS fuselage is an 1" (25mm) too short for the wingspan, the FMS wingspan is approx 57" wingspan and the fuselage is too short for that length.. According to some of the best drawings I can get of the Mustang.... the Leading Edge of the wing to the spinner back plate is very close. The 25mm is missing from the Trailing Edge of the wing all the way back to the rudder hinge line. It also puts the horizontal tail too close to the wing, reducing dynamic stability and tail power..... but for a model... it's probably OK with the CG in a conservative position. One should always discount the spinner and the rudder in the length of the model as they are always notoriously the wrong shape. Best to scale the model where it counts... back of the spinner to the LE of the wing, wing chord and distance between to the TE of the wing and the LE of the tail. The FMS gets the first two right, the last wrong by 1".... that is actually a lot!
Tom Hunt: Use the black wet/dry sandpaper that you can usually find in Home Depot or Lowes. I use the 220 (or 240) grit first and then the 320 before I paint. You can wet sand if you like to keep the sandpaper from loading up, but I never saw it necessary.
Tom Hunt: I think I may have found a reasonable matching paint for the Mustang. Krylon Metallic enamel #1401 Bright silver appears to be a pretty good match with a couple of coats.
Pedro: (German forum board. Yes there is a build thread on a German forum) The Silver Chrome Effect Spray of Dupli-Color has the same color as that of the Mustang.
Tom Hunt: Great Planes Canopy Mod...I tinted the canopy with royal blue Rit Dye and added the aluminum tape frames. Bring a big pot of water to a "near boil" and then turn down the heat just to maintain the temperature. Dump in the whole package of Royal blue and stir with a spoon for a minute. Take the canopy and dunk in the dye for a "five count" and pull it out and cool it with cold water in the sink. Repeat until the right color is achieved. If your pot is not big enough for the whole canopy, you can dunk half at a time, each side getting a "five count". Great Planes 40 glow kit P-51 canopy is a much closer shape to scale than the FMS canopy.
MYC: I too was doing that canopy mod but I cut along the factory lines for the Great Planes canopy, and when I placed it on the tub it was too short. Don't make my mistake bro, place it on the tub first and you'll see where you'll need to cut.
Haiduk: NO paint sticks well to the EPO foam unless its prepped first. Masking tape easily lifts any types of paint. I did a lot of testing with paints/primers to prep the EPO birds. I usually clean the EPO with 90-99% alcohol (to remove any of the greasy mold release agents) then spray with Dupli-Color Adhesion Promoter. Spray the color within about 10 minutes of the Adhesion Promoter and the color stays put. I found that if you first prime the EPO with Dupli-Color Adhesion Promoter then even the "buck-a-bottle" artists acrylics sticks very well to EPO foam. Masking tape doesn't pull paint if you allow it to cure out completely before masking. I haven't had any paint flaking due to flexing of the foam either. I'd recommend picking up a can of the stuff and do some paint experiments on scraps. It's good stuff. You can pick up the Adhesion Promoter at most auto-parts stores. Most automotive "trim paints" stick well on the EPO without priming too.
Tom Hunt: Post #916 The side view I posted shows the antenna UHF and VHF attachment.
Retractable Main Landing Gear:
Main Landing Gear struts come with pre-installed large 2 3/4 inch diameter wheels with Plywood skirts. These retracts are plastic but have proven to be durable! There are however some issues that should be addressed to ensure that they remain in tact. First, Topkits and Licobra both found that they did not have the struts (gear legs) far enough into the square flange of the retracts!! Unfortunately LiCobra found this out after a landing on a not so good surface. Second, Guapoman2000 found that the two small screws that secure the strut come in contact with the plastic housing of the retract will cause the landing gear to not lock in the "up" position into the wheel well of the wing. Third, Tom Hunt and others found that in cold weather the plastic retracts become very brittle and are subject to breaking as well.
Notes from the Main Build Thread:
Topkits: Seems that I was more lucky with the retracts. Mine worked perfectly, also servo travel adjustment was no problem with the Futaba T12. The only problems I have with the gear, same issue as you with the thread in the gear legs and my gear legs don't fit deep enough in the retract, so I have to file a little on the square flange of the legs!
Lenop: Regarding the retracts, if you put them on one channel, try to make a retract linkage with a (rather big) Z-bend in it. This will introduce some extra flex or spring around the servo end points, and can make the retracts work better.
Guapoman2000: Post #1137 I have found the retract servos that come with the FMS model with retracts very adequate as you have a good size servo (mini size) for each main gear. However, as experience tells us, if those two small screws that secure the strut comes in contact with any part inside the actual retract plastic housing then, you will encounter ill fated lock results or lack luster results, especially going UP into the wheel well. The Lock down should not be a problem as the two screws securing the struts are not interfering by this time in the game! If the retracts are NOT locking in the DOWN (very important) then, the RC modeler is not adjusting the end point travel necessary to account for LOCK. Post # 1184 You need to stick to mini servos that have at least 45 - 50 in-oz.
Guapoman2000: Post #1188 What I did find is those two small screws securing the actual strut that causes binding when the retract strut gets close to the wheel well and causes friction within the inside wall of the plastic retract housing.
Forward Rake Mod:
Almost a "need" to do or "have" to do mod in my view! Personally I like Tom Hunts Forward Rake mod of the main landing gear and plan to do this mod. So I will be covering Tom Hunts mod in my blog since it is what I plan to do for now. There are others who also incorporated their own version to obtain more forward rake of the main landing gear as well, and have had excellent results.
Notes from the Main Build Thread:
Tommy D: If the model is balanced correctly “flying” then where you place the pack to obtain that balance should not effect the nose over. Rule of thumb on a tail dragger wheels should extend to/past the Leading Edge of the wing to help prevent nose over’s. Lets be realistic for a moment however. Model weights what... 4.5lbs? 600+W in most cases. It's not going to remain on the ground very long “even less with flaps“. Same thing goes for landing. I mean it's got a 16oz or so wing loading?!? That's less then most 40 size trainers! Then you add flaps! It should be about the slowest landing Mustang one would ever witness.
Tom Hunt: The first thing I noticed on my FMS model is the lack of any forward rake in the main landing gear. The attitude this model sits at makes it VERY easy to get it up on it's nose even on the best of landings.
Tom Hunt: I thought the forward rake would require me to modify the wheel wells, but on closer inspection, I think you would need to do this even without the forward rake. The strut and wheel hits the inner foam long before the gear mechanism gets to an up-lock condition. There seems to be plenty of foam between the well and the upper contour to remove what you need. I did break through into a servo wire channel, but that should not cause a problem. I just used my Dremel tool and a sanding drum to remove about 1/4" of foam in the bottom of the well. You must do the strut area too. I also added about 1/32-1/16" worth of washers between the hub and the strut to lift the tire off the inside of the well a bit too. Next I will have to remove some foam on the lower skin to get the LG door to sit properly.
Tom Hunt: The landing gear position is problematical. Everyone should really try to rake the gear forward on their models. It will just go up on it's nose every time in the stock position. I have already added about 5/32" (4mm) ply shim under the aft screws which basically puts the gear mount flush with the lower surface of the
wing. I also can see that with just a couple of plastic ferrules in the foam to accept the screws, that these units are eventually come tearing out of the wing. Glued in hardwood rails will probably be the order of the day after the first bad landing.
Tom Hunt: I thought the forward rake would require me to modify the wheel wells, but on closer inspection, I think you would need to do this even without the forward rake. The strut and wheel hits the inner foam long before the gear mechanism gets to an up-lock condition. There seems to be plenty of foam between the well and the upper contour to remove what you need. I did break through into a servo wire channel, but that should not cause a problem. I just used my dremel tool and a sanding drum to remove about 1/4" of foam in the bottom of the well. You must do the strut area too. I also added about 1/32-1/16" worth of washers between the hub and the strut to lift the tire off the inside of the well a bit too. Next I will have to remove some foam on the lower skin to get the LG door to sit properly.
VQ P-51 Struts Mod: (Coming soon)
Scale and Non-Scale Tailwheel:
First, the Full scale Mustang tailwheel retracted forward.
Version 3 can come with either tailwheel version, scale or non-scale. The steerable non-scale tailwheel which connects via rod into the rudder, is also is in the wrong non-scale location. The scale version is located in the correct position and has its own servo for steering, and can be made retractable “if” you add a servo. Note that some scale tailwheels have a block that was installed by the manufacture that prevents it from being able to retract, making it a fixed tailwheel in effect. This block is easily removed, and is all that prevents the retract from working in addition to adding servo. If you have the new tailwheel and want the scale one, order it. FMS did not change the shape of the fuselage EPO moldings, they just put a large EPO plug in the spot where the scale tailwheel retract is housed in the fuselage. You have to cut that out and install the retractable tailwheel. (See Photos)
Version 4 is at least being delivered with a non-retractable but steerable tailwheel in the scale location. It is a scale size wheel on a rod connected to a servo within the fuselage. (See Photo)
Retractable Tailwheel Mod:
Personally I feel that if I am going to go to the extent of having retractable main landing gear work, then having a retractable tailwheel ONLY makes sense! But to each his/her own as the saying goes. My Version 3 came with the ugly non-retractable tailwheel that was to hook into the bottom of the rudder via a wire rod, which made it steerable as well. I have already acquired the retractable scale tailwheel, and a friend who has this aircraft as well made me the rod assembly as when you order the retractable tailwheel it does not come with the rod assembly!
One issue that many have had is that the tailwheel strut is not very strong and a mild hit will bend the strut! Some folks have not had any issues with theirs bending at all as well, so it is a quality control issue of material being used by FMS. Several folks have modded this as well which I will try to cover some of those later on.
Notes from the Main Build Thread:
LiCobra, Beltpilot and Lenop started the tailwheel retract conversion beginning on page 45 on the main thread (see link at the beginning of my blog)...thumb through the pages and you'll see the progress....posts #662, 695, 717, 931, 1035.
Topkits: I decided to install the original scale tail wheel. It was just a matter of removing the EPO-plug in the fuselage. I shortened the tail wheel by 1/2 inch and now it looks far better. I just cut 1/2 inch on top of the aluminum tail gear arm, drilled a new 2.5mm hole and made it fit on the wheel hub again. Pretty easy and effective!
Lenop: Post #695 with two photos. Only thing to improve is securing the servo to the fuselage better. I will do this by sticking the servo to a rectangular piece of plywood. That plywood will be attached to the rear bulk head of the fuselage.
Beltpilot: Now to the fuselage, the tail to be more exact. According to what I know after my conversations with Ready2Fly and Osmot, the fuselages are the same for both tailwheel versions. On the new, unsteerable tailwheel version the foam plug might be closed all the way, so bigger and in one piece. On mine the spot where the new tailwheel would be attached to also has an indentation, right around and behind the spot where this screw was sitting that I had trouble with. So if you have the new tailwheel, just take it off, take out the foam plugs and install the steerable tailwheel, there should be no problem. Gluing it would be the easiest way to do it, but the glue needs to hold the servo really good. I am thinking about using hot glue there.
Lenop: Post #717 with 4 photos. I attached the servo to a piece of plastic (yellow in pictures) with thin, double sided fiber tape. Very strong, sticky stuff. It is used for laying carpets. The yellow piece of plastic with the servo is on its turn attached to the fuselage with the same tape. The wire of the steering servo is routed backwards through a "channel" above the tailwheel housing that is formed by the vertical stab. I then placed the small, most rear plug back. (see lat picture). Only thing to do is shorten the tailwheel itself. I adjusted the linkages and servo arms/travel so that I can hook both the main gears as the tail wheel to one channel. Works perfect!
Beltpilot: Like this, it is always possible to change the servo if something goes wrong or the servo breaks down. Which servo did you actually use, is it a 9g? Plastic or metal gear? Also, how did you attach the retract to the fuse? It was glued in before, did you re-glue it or did you do something else?
Lenop: Not sure how I will attach the retract to the fuse. I think I will use the tape again or hot glue it. This to make it possible to remove it if something breaks down. For servo: I just used a no-brand 12g. servo with plastic gears. As long as you make sure the retract mechanism locks in both up and down position good, like you described before, then I think not to much strain is put on the servo, the tailwheel being so light.
LiCobra: Post #931 The tail wheel just hung down way too low...so I altered mine about 3/4". I made the part to activate the tail retract similar to Bernhard, but used brass and also altered the housing so the control rod exits the front like Lenops set up.
Beltpilot: Post #1035 This last part is about the tail wheel retract. To have it done the way I did - a big thank you here to Lenop and all the other guys who had the idea for this - you need to change the location of the pushrod as there is very little space behind the retract mechanism. After changing that, you have plenty of space to mount a servo and have the retract going
LiCobra: Post #3053 If I did it again I would use a much longer rod to the retract and put the servo up front by the elevator/rudder servos.
Servo Rate Reducer:
Personally I feel that having a beautiful looking aircraft that is equipped with retracts that just snap up or down does not do it justice! Again, this is personal preference, therefore a servo rate reducer is a must have for a scale appearance. I have included a few examples from the main thread below as well.
Notes from the Main Build Thread:
Post #924 Dionysus Servo Rate Reducer will limit the rate of change for a servo signal. This will slow the servo down for use with retractable landing gear or airplane flaps. The rate at which the servo moves is usually about 3 to 4 seconds end-to-end. Servo Rate Reducers are designed to be used only on standard servos. Using them on specialty servos like retract or digital servos will produce undesirable effects. If you can plug in the servo to your radio and smoothly move it from one side to the other using the transmitter stick, then the servo rate reducer should work for that servo. A single Servo Rate Reducer can be used with a Y cable to slow down two or three servos on the same channel.
# Weight: 1g
# Power Consumption: less than 27mA
# Input Voltage: 4.5v to 5.5v
Post #925 Turnigy 3 Channel Servo Speed/Direction Regulator PRODUCT ID: TSSR-3
A fully adjustable 3 channel-out Servo Regulator which can be used on any receiver channel and will increase the servo travel time, direction and duration. Great for scale model retracts flaps and canopies where scale detail and flight characteristics are important. No more ((boing!)) cartoon like landing gear action.
Input: 1 servo Channel.
Output: 3 Channels.
Options: Travel Speed & Travel Time in both directions.
Guapoman2000: Post #977 Remember the Slow Down Module will make the regular Servo lose torque as it works on speed. I don't know what kind of Retract Servo they installed in this larger Mustang but, I may need to use a HS-85MG or larger that has the largest Torque as the slow down module will slow down a lower torque servo too much and then, the retracts will not lock!
Guapoman2000: Post #988 Bernhard Glad to learn of the "STOCK" Retract Servo being able to work well with the slow down module. If you got the adjustable slow down module, I was curious to the setting? BELTPILOT: Carlos, well, I got the Turnigy Module that most people use, the setting I got right now for the main gear is about half, resulting in a cycle that takes about 3 or 4 seconds. The tailwheel will be a little bit faster, I will let it retract in about 2 seconds as that looks more scale imho. Guapoman2000: Thanks Bernhard! It is funny thing when I was setting up my Retracts on my World Models P-51D Mustang of 50 inch wing span (Balsa and Light Plywood) model, I used the Hitec HS-81 and worked great without Servo Reducer device. However, when I did install the servo rate reducer the wheels slowed down and the Servo just quit with almost 2 more inches to go for complete retraction into the wheel wells. I had to fly the model and gain altitude and then flip the model inverted to allow for complete gear retraction while using the servo rate reducer. However, I changed out the Retract servo to the Hitec HS-85MG with lots more torque and it worked perfectly using the servo rate reducer. I am sure if I had used two HS-81's, one for each gear side would have resulted in the same results as using one Hitec HS-85MG
Guapoman2000: Post #1140 A traditional Retract Servo and not a regular servo meaning that you can not use a Servo Rate Reducer. Post #1143 Believe me when I say that these larger high impact plastic retracts that FMS supplies this model is one of the best in durability and design as they actuate with one servo per side. I have been dealing with Retracts ever since I bought a one certain World Models P-51D Mustang with retracts that actuate with just one servo. That model "is" traditional Balsa / Light Plywood and spans almost 50 inch wing span and my model came in at less than 3lbs. fully flight ready. This model came with plastic retracts and did not last more than 10 flights until I had to order new ones. Post #1147 Traditional Retract servos are totally different than regular servos. This FMS model uses regular servos, if I am not mistaken otherwise the servo rate reducer device would not work nor travel adjustment would not work as well. Has nothing to do with the transmitter you use.
DR1Driver: Post #1268 I recently read somewhere that servo rate reducers should not be used with some BEC's. I believe it was in the BEC specs for some BEC's that I was looking at. They can cause the BEC to fail.
Stay tuned for more! I have a LOT of mods such as additional wind spar, front cowl mod to allow air into the fuselage, elevator mod, ect., (with photos from those who have done them already) and just need time to put it together!
ImagesView all Images in thread
Last edited by TheOldGuard; Apr 16, 2010 at 09:27 PM. Reason: attached photos
Thanks JBC! Still got a LOT of info to post when I get time to do it! Mostly just re-posting things I felt were important to me. I am not getting into all the different motors or electronics since that is a personal "fav" of most, and not even getting into 2 blade props either. I still have mods and such to cover as well and as much info as there is on this aircraft right now it may never be done !
Greetings, this is my first post on this fine forum. Forgive me if answers already exist.
I appear to have a version 4 model. I base this on the following:
1. According to the box it has a 50A ESC
2. It is the 9 servo retractable tailwheel model. The servo is there but no instructions regarding its use.
3. It has a recommended 4S 14.8v 3200mah Lipo battery
However, the instruction manual is so utterly pathetic that it is effectively useless.
I am concerned about the comments about the earlier ESC not being up to the job. However it does say that this is a 50A model so perhaps it has been upgraded. Does anyone know please, as there are no instructions for its use at all?
Another thing that is puzzling me is that the ESC does not connect directly to the reciever throttle channel, it goes through a small circuit board first. I have no idea what function this provides. Again, no instructions at all, could anyone assist me please?
The manual has nothing as useful as control throws, indeed I was amazed to see that it actually showed where the CoG should be. I was most interested to see mention of Hobby Lobby’s Instruction Manual. Is there a decent instruction manual? The model seems to go together well enough but I would like to know what electrics it has inside and how they are programmed or I may have to take the Tornado XP-60A ESC/BEC out of my 68 inch span scale Eflite DHC-2 Beaver, but it seems like an awful lot of trouble to go to every time I want to fly a different plane!
Speaking of the Beaver brings me to a last point, for the moment at least. Eflite recommend lots of cooling air. There seems to be very little cooling for the FMS Mustang. I can see lots of possibilities, like opening the air scoop for example. Has anyone had any problems in that regard? Many thanks.
FliBiKnight welcome to the forum, and there are a LOT of outstanding individuals here as well & their knowledge is amazing! Also, welcome to the madness of the FMS Mustang!
Thanks for the additional info on the Version 4 as well!! YES, the instruction manual, well SUCKS ! Hobby Lobby does have a decent manual and I am going to try to attach it to my blog as well as here for you.
Yea opening up the cowl where the fake intake is located is an easy mod and the best for allowing air into the fuselage, and with the retract tailwheel opening it allows for the air to escape. This alone should allow plenty of air for cooling the electronics.
The stock electronics are always suspect of being cheap made! With that said any and all electronics in my opinion should be replaced, Even with the higher 50A ESC in Version 4, installing a separate UBEC is a safe mod just in case the stock ESC bites the dust while in flight...you do NOT want to loose control and have it crash! I am basing this off of folks that have this aircraft that have had issues with the electronics on the ground and airborne! Now I want to say that there were reports that FMS installed a separate BEC in Version 4 Mustangs. Also one person, Carlos had wires that were cut from the factory and loose wires as well.
Hope this helps!
Flibiknight this is not the forum for the FMS P-51 this is Dave's blog regarding the plane, if you want the forum for this plane then goto https://www.rcgroups.com/forums/show...92043&page=188
Thanks for the welcome and the very quick reply. I know there are some top class people here, problem solving, flying testing, helping less experience people like me.
Thanks very much indeed for the decent manual, that's a huge help. Also, I've read through that vast thread on the Mustang. I see now that I need to cut away some foam and put in yet another servo. The tail wheel steers but there's nothing to actuate the grey plastic retractor gear. That'll make it TEN servos. Luckily I have some high torque 9gm hitec servos so that should not be difficult as all the instructions are all in the thread.
Because I'll have such a lot of value flying around up there, it seems daft not to get a decent quality ESC/BEC. So I will get a quality 50amp one. As you say, I don't want to lose control. Also I'll only need to make the change once and it will be done with. It may be that the device between the receiver and the ESC is a BEC, but how to tell. I can only just see it. The white wire goes straight though, unused by this thing, it only acts on the black and red power cables. But how do you program it if it is a BEC. The Chinese make a nice good value plane, but the instructions are abysmal.
It's a beautiful model though, and it'll really turn heads I just know. was amazed to see that one, Carlos's I think, literally jump for the sky on only the scale prop. I think I'll go for the twin blade though to get longer flights from the better performance rather than speed. I like slow, slightly more scale performance anyway. It's not meant to be a pylon racer IMHO. Or try a three bladed prop to keep a slightly more scaleish look along with the efficiency. I really like those servo slow down things that make the wheels lift nice and slow. They's available here in UK too.
Thanks for your help!
Ahh! OK, thank you
No you haven't my friend, I've been a little busy with other projects like getting an F-15 EDF up and running, a few repairs here and there and some bench testing. I'm actually looking at dropping the prop size(yes getting rid of the big 4 blade ) and running 5S and a smaller prop. That will allow me to draw around 40-45A with the same performance instead of close to 60A with the current stock 4blade setup. This will give me around 10 minute flight times which I'll be much more happy with and still have great performance, sorry but 5min flights just don't cut it for me
Touchy elevator and I'd turn your rates down to about 60% with some expo just until you get a feel for her. She has plenty of power and maybe on your first flight just leave the landing gear down and go over her once back on the ground to make sure nothing's come loose or shifted while in flight. Goodluck
maybe you're interested in the motor / prop data of the original motor that came with the FMS P51D (V3):
I found this here: http://www.bungymania.com/imageshome...SELECT=p51dfms
Here you see how inefficient the beautiful 4bladed prop is...
Yes we are aware of Bungymania and I even refer to them as well, great source of information! In my blog I stated the review that Bungymania stated..."By replacing the engine with a more powerful one wins 10% but still it raises consumption and reduces the duration of flight." It also states, "the stock propulsion base is effective." So, for me, as I am not a go fast turn left fella, the stock 600KV fits the bill! Carlos (Guapoman2000) has consistently been satisfied with the stock 600KV as well. I personally see no need to mess with motor mounts, weight issues, and such when the gain is not going to be noticeable to me. I also have no plans for utilizing the stock 2 blade, I am sticking with the 4 blade propeller no matter how inefficient it is...just a personal matter or preference.
Thanks for the comment though and happy landings! Look forward to seeing you Mustang in the air again!
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