Greg Covey

The BAe Hawk is another member to the Styrofoam EDF jet model series from [link=http://www.flyflyhobby.com/english/product01e.html]FlyFly Hobby[/link]. These models are distributed overseas by [link=http://www.hobby88.com/shop/]Hobby88.com[/link] or here in the U.S. by Electric Jet Factory [link=http://www.ejf.com/index.php?main_page=product_info&cPath=69_112&products_id=524]EJF.com[/link].

If you are not familiar with FlyFly Hobby foam jet models, they are uniquely engineered designs that are made from EPS foam. The large jets are designed for 90mm EDFs and fit together like a precision 3D puzzle piece. They come with the ducted fan unit and fixed landing gear. They can be hand-launched over grass or fitted with optional retracts.

The BAe Hawk is powered by a single 92mm ducted fan unit that uses a B36-class 1000w brushless motor. The kit comes with the scale aluminum suspension landing gear and the fuselage is separated by 4 pieces for easy shipping. The Hawk is designed for both fixed and retractable gear. The fuselage has enough room for high capacity battery packs for longer run time and higher air speed.

Specifications:[ul][*] Wingspan: 1365mm (53.5")[*] Length: 1465mm[*] Wing Area: 29dm sq.[*] Height: 535mm[*] Airfoil: RG-14[*] Weight: 730g (body)[*] Flying weight: 2430g (with air retract landing gear)[*] Ducted Fan Unit: 92mm (included)[/ul]
Requires:[ul][*] Motor: 1600 - 1800kv (Shaft dia 5mm)[*] ESC: 60A w/BEC[*] Battery: Li-Po, 18.5v-22.2v(5 - 6 cells), 3600mAh, 20C[*] Radio: 4-5 channel[*] Servo: Micro servo (8g) x 5, torque > 2.2kg[*] Optional air retract available[/ul]

Greg Covey

The large box is filled with big foam parts and support pieces like a ducted fan, canopy, landing gear, and plenty of precision cut plywood.

For as well designed as this model is, little thought has gone into packaging. Fortunately, the minor dings in the soft EPS foam are easily glued or repainted. A nice decal sheet is included but the manual reads more like a series of break-out drawings than a step-by-step assembly list.

Greg Covey

A closer look at the 4-piece fuselage reveals the 3D-like puzzle fit. The pieces fit together extremely well. Aside from the delicate EPS foam and outdated packaging, the rest of the design is well engineered.

Greg Covey

My Hawk will be powered by the following components. The AMMO 36-56-1800 motor is $20 less than the Typhoon EDF-600-32 motor and has a higher Kv for greater speed. The FlightPower ESC can be hammered hard even in heli applications up to 80-amps and doesn't need a separate BEC for up to a 6s Lipo.

[ul][*] Included FlyFly 90mm DF[*] Great Planes AMMO [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLWZ9&P=7]36-56-1800[/link] motor[*] FlightTech [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVBY0&P=7]60-amp ESC[/link][*] FlightPower LiPo 18.5V 5s [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRWE6&P=7]EVO30 4500mAh[/link] pack[*] FlightPower LiPo 22.2V 6s [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRWE1&P=7]EVO30 3200mAh[/link] pack[/ul]

The 5-cell FlightPower pack weighs 21oz compared to the 18oz 6-cell pack so they are close in weight. The higher capacity 5-cell pack will provide longer flights but not fly as fast as the 6-cell pack.

The AMMO motor mounted easily using the 5mm adapter that comes with the Hawk. Note that the motor wires are extended to 23" lengths. This allows the ESC to enter the battery compartment under the canopy for easy access. I tested the completed assembly before mounting it in the fuselage. It ran very smooth with almost no vibration.

Greg Covey

The fuselage is essentially pre-assembled inside before gluing the two halves together. The ducted fan unit and pre-assembled exhaust tube fit like a glove inside the fuselage.

My Hawk is using the new Hitec [link=http://www.hitecrcd.com/servos/show?name=HS-5065MG]HS-5065MG[/link] Digital Programmable servos. This high-performance micro servo features Hitecs digital, programmable circut for incredible resolution, centering and holding torque. It also features metal gears, a top-ball bearing, and 31 ounces/inches of torque with a quick transit time of 0.11 sec at 6 volts.

Greg Covey

The 4-piece fuselage was glued together in two stages using 20-minute epoxy from Bob Smith Industries. The epoxy is thin and can be brushed on with a soft piece of foam or disposable brush. Since the epoxy takes 20 minutes to just start setting, it allows you plenty of time to wipe off any excess after pressing the fuselage halves together. I used cloth strips to hold things together overnight as the epoxy takes 8 hours to dry.

I also use this epoxy to "paint" a clear protective coat on areas that may see more impact like the nose, fuselage bottom, and leading edges of the wing and fins. The rest of the plane will get a coat of clear gloss Minwax Polycrylic. This water-based spray dries fast without fumes and provides durable protection on foam models.

jjantti

pssssst Hey Greg. Before you try to fly it...
Rotor is upside down.
/Jyri

Greg Covey

Hi Jyri,

Thank you for joining RC Universe to point this out. It was something I forgot to mention when I posted the photos above.

You are correct that the rotor is backwards when using the HET motor. However, when using the AMMO motor that has a shorter shaft length, you need to flip the rotor. This is needed because it hits the duct centering. What makes this possible is that the rotor is symmetrical and the motor spins in the same direction so it still works with the air guides in the duct.

My Hawk has already flown several times but I have not made the videos yet using 5-cell and 6-cell packs.

Regards.

Greg Covey

Before installing the canopy top, I mounted the [link=http://www.nitroplanes.com/rcmodelpilot8.html]Red R/C Model Pilot #8[/link] from Nitro Planes. These pre-painted model airplane pilots are designed for CMP's range of ARFs and added a nice look to my Hawk.

Instead of using the manual suggestion for a screw to hold the front of the canopy in place, I glued a spare piece of plywood to act as a tongue which simply gets inserted into the foam channel of the fuselage for a cleaner look.

jjantti

Thanks for the warm welcome.

Wow, this kind of blade symmetry is new to me.
I had that fan on my hands when bought the FF F86 but sold it as soon as I got it. I newer took it off the bag...
I'm using Midifans. It sure has blade asymmetry. Have been running it for years and have no reasons to try replace it.

Have you compared the power vs. thrust on both ways of the rotor? I'm still not convinced it will work perfectly that way.
Difference must be small but the concave blade root should ideally rotate on one way only I think.

At least this is what I have been told about lectures concerning gas turbines.
Blade root might benefit having just concave shape since it works more on impulse forces. Blade tip has more rotational speed acts more like a standard prop.
I must be kind of obsessional about the efficiency since I think things like that [sm=50_50.gif]
I have no intentions to argue but I'm just curious.
/Jyri

whissel_blowa

The rotor cannot be reversed if you want it to function the way it was designed, besides which the stators inside the housing are designed for one direction of flow... If the shaft is too short you need to machine up a spacer sleeve from aluminum and slide it onto the shaft adapter, this is what we do with the short can 3650 motors so that the Midifan PRO rotor will fit correctly.

Stock rotor is very inneficient and aggressive, it sucks a lot of amps and puts out less static thrust than a midifan rotor.

Higher Kv does not necessarily mean faster, if the motor is a short can like the 600-32 then it is not going to give you an exponential increase in RPM going from say 5 to 6 cells. I know, have had all the popular setups on the bench, the 600-32 and similar size motors in the 1800+Kv range are good for 5 cells only in the Midifan, I would never run them in the stock flyfly fan, even on 4 cells the 600-32 pulls 54A.

The HET600-32 is rated at 2000Kv but is actually a mimick of the MEGA 22-30-2 and both are around 1800Kv same as the Ammo.

I would never run digital servos on that ESC, in fact on 6 cells I would never use the built in switchmode BEC, they are really only rated to 5 cell voltage, once you go to 6 cell you need a more expensive IC. We use HV-UBEC's in all the FlyFly jets, good for 5A continuous and capable of running the 7+ servos that usually end up in these large models.

The 6 cell 3200 pack will likely do no better than the 5 cell 4500 due to the fact it will sag out a lot more under load, especially if you are using the stock fan rotor, your load on the 1800Kv motor will be high, I would guess close to 60A on 5 cells and potentially 75 on 6 cells although you dont have the battery right now to achieve that.

Best setup overall for the FlyFly models is the HYK long can motor in the stock housing with Midifan PRO rotor on 6 cells, 1100-1200 watts and over 2.2kg static thrust, runs at 50A all day long on 4000mah 6s1p 25c packs which weigh just under 23oz. Battery weight is the least of your worries, the more the better, we use anything up to 750 grams, the extra power from the retained wattage more than makes up for the slight increase in weight and the planes generally fly better.
Cheers!


www.extremerc.com.au

Greg Covey

Jyri,

Most rotors are not symmetrical so they can't be reversed but the FlyFly rotor is symmetrical so it works. What our friend from Australia is missing is that it still spins in the same direction so the stators inside the housing remain efficient. Try not to confuse turbine requirements with EDF requirements because they often differ. Most notably is the air intake requirement which is why EDF conversions of turbine-powered jets has not taken off.

Many people have their favorite ways to do things and sometimes harp on maximum efficiency but there are often many solutions. The ducted fan that comes with the FlyFly models is very usable and there is no need to replace it. Notice the promotion at the end of the post for Extreme RC in Australia.

Regards.

Greg Covey

The tail assembly was easy and straightforward. I did, however, replace the control rods that came with the kit with thicker ones and used a simple L-bend at the horn end so it could not slip out of adjustment.

The key here is to make sure that the tail piece swings freely and that the screw in the holding collar is properly positioned for a full swing.

Note that I added some black trim tape to the tip of the exhaust tube for a better look.

whissel_blowa

Not promotion Greg, purely a link to avoid the usual questions of "what would you know" etc. I dont promote or sell into the US (and thats 95% of your readers right there) so that sorta says it all doesnt it

The FlyFly rotor is not assymetrical, its close but not exactly the same and the blades have a definite chord. It is also inefficient, and the quality is very hit and miss, most are bored off centre and it is very difficult for the average user to get them balanced and running smoothly enough to be reliable. I have seen plenty of them running very badly, they put load on the motor bearings and fatigue the housing, throwing a blade is not uncommon.

The Wemotec Midifan PRO rotor is just so much better, its not expensive, can be bought from many dealers in the US, drops straight into the flyfly housing as its a copy of the wemo housing, and it comes factory balanced, success rate for the average user is much higher.

I dont think I am harping on about anything, to me the fan is a no brainer when the cost is so reasonable.
http://www.ejf.com/index.php?main_pa...roducts_id=538

Greg Covey

Understood. I certainly agree with you that the quality issue may be hit or miss. I also agree with you that there are more efficient DFs and available upgrades. Perhaps I was lucky on my setup that has virtually no vibrations. However, I have had other DFs that throw rotors for no apparent reason and believe that proper mounting of the collet adapter is very important.

Your statement on the FlightTech 60A ESC is a matter of preference rather than fact. Using 5 or 6 cells has little effect on the switch-mode 3-amp rating. I would recommend to measure the load and determine if it is higher than the rated 3-amps on the internal BEC. If so, I would then use an external BEC with higher rating like you are doing. My Hawk only uses 4 digital servos with programmable current limiting.

In the competitive Western world, we have a tendency to highlight the best and throw away the rest. Often, what we toss or ignore is not junk.

Let's agree to disagree on the other issues. Since I typically merely document my findings without harsh judgment, I'll eventually post flying photos and videos for others to make their own decisions.

Regards.

jjantti

Hi Greg,

I'm familiar with different goals with EDF and turbine world. We want air speed not pressure like those kerosene guys. Good point there.
I'm also familiar to the fact that duct and fan efficiency makes the plane airborne eventually.

[boring story on]
I made tiny(1:17,1) pretty scale F-18C years ago. Begining of the millenia don't recall anymore... It was to be flown with twin GWS EDF50's. It did not.
Intake was too small and had serious turbulence problem. I almost trashed the thing at once.
After a year or something I read more about ducts and other 'need to know' theory.
Built all the ducts again this time for EDF 40's. Everything else was the same(the plane, battery,power, motors).
It sure was no rocket but it flew OK!
[/boring story off]

Somehow I just doubt that designer of the Haoye fan did not know any better. It sure is a copy of something. And Fly Fly is copy of that if not the same rotor ...
The blade root looks for me to be copied from turbine blades IMHO. It has nothing to do with EDF's or prop's for sure. Angle of attack is roughly 80-85 degrees.
I doubt the there is airfoil that work on that environment. And putting it backwards kinda makes it worse in my eyes.

I tried share this 'learn by sweat' knowledge with you to make your hobby easier.
At the same time I know this is hobby and we all have our own ways to do it. We can just buy more power with few bucks and go flying. I get that too.
But anyway we have to get the power transfered into airstream to get our plane move. That was my point.
But please let us know if it works.

/Jyri

whissel_blowa

Actually this ESC (unless I am mistaken and happy to accept such ) is a Hobby Wing 60A with shielded switchmode BEC, I believe FP get their ESC range direct from the HW factory, and I doubt very much they are any different from all the other rebadged HW ESC's, much like their batteries. So if it is the HW60A Pentium ESC then the switchmode BEC is designed to run up to 5 cells, and the factory states it becomes very inneficient on 6 cell voltage. I believe it is the IC they are using, it is the same one they use in their 3A UBEC. The next step up is a high voltage IC that can handle up to 42v input or 10 cells and put out 5A.

I dont really understand what you mean by highlight the best and throw away the rest, the FP ESC is a classic example of the complete opposite


JJantti you are right, the Haoye designers were not thinking along EDF lines, it is quite obvious in most of their fans. The most successful of the chinese fans has been the 70mm copy of the wemotec rotor, no need to wonder why

Greg Covey

The FlightPower 60A ESC is not made by Hobby Wing and the programming is proprietary to FlightPower. However, the switch-mode BEC may be the same chip since most places use common integrated circuits. There is no percentage to the "very inefficient" specification for the 6s input voltage. Since switching regulators are normally very efficient, it doesn't much matter if the efficiency drops on a 3-amp output when it is fed by a large LiPo pack. Remember that the servo current demands are very burst and not continuous. When using brushless motor and Lithium packs, a drop in efficiency merely means a slightly higher current draw or slightly shorter flight. The performance level will be very similar.

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The Hawk wing halves and custom plywood supports were assembled using 5-minute epoxy. The only place I used the glue that came with the kit was to secure the bottom panels. It was spread liberally along all the seams and let to dry overnight. Note that the servo lead and extension is routed through a shallow channel that you need to cut into the foam.

I replaced the thin controls that were supplied with the kit with slightly thicker ones. The L-bend at the control horn is secured with a small piece of shrink tubing and CA.

The one-piece wing was both strong and light. When not using landing gear, the wheel wells make a perfect spot to hand-launch the Hawk.

whissel_blowa

Fair enough, just like the APL factory in Malaysia never assembled FP packs, and the cells never came from Enerland, then the factory was 50% owned by FP, then it was everyone else got the cells FP rejected...

Sorry if I sound cynical but the FP ESC looks EXACTLY like a HW60A Pentium, the board is the same shape, heatsink the same, label the same, silicon wire is the same, and according to HW engineers the switchmode BEC is not very efficient when running over 22v and they do not recommend using it when 6 cell packs are connected. I realise a switchmode supply is far more efficient and able to cope with loads easily compared to good old linear M7805 regulators, but there has to be a design parameter to the chip as well right? Maybe this is what the engineers are getting at...

Servo loads are hard to guess, best to log them and be sure, especially with digitals where their holding current can be 4 times as high as their normal operating current, and most of these large jets have quite a lot of load on the servos even in general flight.

Greg Covey

Before installing the wing, the aileron servo leads are connected to the Y-harness and lay flat in the wing top channel so they don't interfere. The wing is self-aligning along the chord on both the leading and trailing edges. It is held secure by two machine screws. Overall, this was a well thought out design technique using laser-cut ply pieces to strengthen key areas of the mating foam sections.

Note that the black foam piece covering the unused openings is cut from the common flooring that look like big puzzle pieces. The foam weighs practically nothing but is durable and shock absorbent.

Greg Covey

I've had some PMs on the Hitec programmable servos so I'll post a bit more about the programmer.

The Hitec [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXSYU0&P=ML]HFP-20[/link] Digital Servo Programmer/Tester allows you to get the most out of Hitec’s new G2 programmable digital servos. The programmer allows users to perfectly match servos in ganged applications or customize several other parameters such as dead band, direction, speed reduction, endpoints and failsafe. The HFP-20 is required to program the overload protection features in the new HS-79XX and 50XX servos along with the standard/high resolution setting in the HS-79XX series. The HFP-20 is backwards compatible and works with all Hitec Digital Servos.

The programmer contains its own internal 4.8v rechargeable battery to power the test and programming functions. The re-charging port is located on the side and designed to use a standard overnight wall charger like the ones used for receiver batteries.

Some of the servo tests are to measure receiver pulse to the servo, measure the voltage supplied to the servo from the receiver, automatic servo movement tests for break-in cycling, and manual servo movement testing.

Programmable Features Include:
[ul][*] Reset to factory default[*] End and center points[*] Direction of Rotation[*] Dead Band Width[*] Failsafe Point[*] Speed (reduction only)[*] Overload Protection (G2 servos only)[*] Resolution Mode Setting[/ul]

Greg Covey

Since the EPS foam on the Hawk is very delicate, you can protect the finish with a combination of Bob Smith Industries 20 minute epoxy (that is brushed on) and Minwax Polycrylic Water-based clear spray paint. You can see the shine of the bottom fuselage that was brushed with the thin epoxy. It takes 20 minutes to even start setting and overnight to fully dry so you have plenty of time to "paint" it on with a disposable brush. The leading edges of the wing and stabilzers were also brushed with 20-minute epoxy as was the front two duct openings and nose tip.

To reduce weight, most of the plane that doesn't come in contact with the ground is sprayed with the Minwax Polycrylic Clear Gloss. Less protection but lighter as it's all a trade-off. I estimate that I added 3oz in weight to help protect my Hawk finish.

The Hawk comes with some nice custom plastics that you cut out and glue in place. The aileron servo arms and control rods are protected by plastic covers which will help on my belly landings.

You can see more of the black foam pieces that cover the unused openings. The common foam flooring, that looks like big puzzle pieces, can be purchased in many colors at most home improvement stores. The foam weighs practically nothing but is durable and shock absorbent.

Greg Covey

More of the Hawk plastics can be seen in this topside photo. By using a black marker, you can give the vents an opened look.

The inside of the fuselage front can look very clean by routing the receiver and wires along the side away from the ESC noise. My receiver ended up just forward of the battery pack. I used some Velcro strips to hold them in place or easily remove them, if needed.

There is plenty of room for my FlightPower 30C 5s and 6s packs. The model balanced well being slightly nose heavy. The battery to ESC connection is easy to make due to the quick canopy release so I removed the On/Off switch and soldered the wires together.

Time for some power measurements...

Greg Covey

My FlyFly BAe Hawk was Ready-To-Fly at 83oz (or 5.2lbs) with battery pack. The plane without a pack weighed 62oz.

I made some power measurements with 3 different packs. The newest pack was my 30C, 6s, 3200mAh pack with match cells.
[ul][*] FlightPower EVO25 5s 5000mAh pack (23oz) 810w at 49amps[*] FlightPower EVO30 5s 4500mAh pack (21oz) 775w at 47amps[*] FlightPower EVO30 6s 3200mAh pack (18oz) 1200w at 64amps[/ul]

whissel_blowa

Hmm 64 amps and 1200 watts? Thats like 18.75 volts on a 6 cell pack, near terminal voltage! What would be nice is to see some RPM figures correlating to the amps/volts readings.

All your figures are showing a cell voltage under load of less than 3.5v which is pretty bad. What was the temp of the packs when you tested them? I suppose we shouldnt be surprised, I see this all the time at our field with Flightpower packs, they sag out under even a mild load and are a complete waste of money IMHO.

Our 6 cell setups sit around 22.5v under a 52A load using chinese made 4000mah 25c cells, this is with a Midifan rotor and thrust is around 2.3-2.4kg. Even when I am testing hotter setups at 70A the packs are still holding 21+ volts at close to 1500w.

Will be interesting to see some video of the Hawk, should be a real parkflyer