mixerfix
02-10-2010, 14:44:19
Built and flown the Hacker Bf-109 foamie. Here are my setup, comments, suggestions and opinions.
Setup:
The setep used was a cheap Chinese everything:
Motor: eBay color4way BL 2208-17 (1100Kv, 30A, 38g)
Battery: Dynam 3S1P 10C 1250mAh
ESC: Who-The-Hell-Knows 30A w/BEC
Receiver: Feigao 72MHz
Servos: Three 9gm Tower Pro blue thingies
Kit Contents:
The plane and its EPP components are well made, precise and clean. The same can be said for the lexan canopy and the plastic horns and pushrod tubes. The wooden bits (in the Bf-109 it is the motor mount) are made of bad and very brittle wood. This is, however, something one can live with. The components that are really bad are the aluminum strengthening spars (about which much later) and the aileron pushrods.
Build Process:
The build is quite simple. The only difficult bit is digging in the servos, especially since the bottom servo (ailerons) and the top rear servo (rudder) meet in the middle, leaving the aileron servo a bit too far out of the plane, requiring some wing scraping.
The annoying bit are the wing and fuselage strengthening spars - made of soft aluminum, they bend and acquire a semi-circular shape if pushed in with pressure along their length. Very annoying. I built the Bf-109 with the aluminum spars, but when building a (related) Pitts, we ditched the aluminum spars for the wings and used a carbon rod. In fact - carbon rods are highly suggested for all strengthening spars.
I decided NOT to emplace the canopy until after a few flights, mainly because the Chinese blue servos are such incredible trash that to get three working servos, I went through six servos in total. Haven't the Jewish people suffered enough?
The provided aluminum aileron pushrods are (a) way too soft and (b) way too short. I ditched them and made steel pushrods.
The ESC was installed as suggested. The Rx was "bolted" on the right side of the fuselage (In my opinion, there is NOT enough space under the canopy for the Rx and two servos) and the battery (since it was temporary) was "bolted" on the left side of the fuselage. The bolt-on was using two wooden planks and a plastic bands.
CG was as recommended.
First Flight:
Hand-launch and a slow lazy flight (I over-propped, using a 10x4.7SF). The plane was NOT well trimmed and I was not sure of the setup or battery, so after a very short, slow, gentle (with a marked drop of the right wing (my fault for mis-aligning the servos, probably), I landed it into a patch of planta genista. The plane promptly cartwheeled and the fuselage BROKE in two places (photographs will follow separately) - right behind the motor assembly (the entire motor section came off and right behind the ESC emplacement. The energy of of the crash was VERY low, yet the breaks were major. The execrable aluminum spars simply bent, providing the fuselage with a very attractive flat S-shape along the length axis. I hand-slapped them into shape, cursing aluminum in general and this example in specificity.
Fixes:
Fixing the plane was done so as to strengthen the entire motor mount area. Three 2mm by 12mm carbon strips were inserted in the top nose section and one
5mm x 15mm in the bottom nose section. The insertions were then CA'd and kicked.
Second, Third, Fourth Flights:
Replaced the prop with an APC 9x4E. Same setup otherwise. Second flight: used to trip plane and cartwheel in a cotton field. No damage, but fixed the trim problems (wrongly! see later). Third flight: Gentle and docile flight, flew for three-four minutes, then switched off motor and glided into the cotton. Very simple and docile flight, no damage on landing.
I did not recharge the battery between the flights - on the fourth flight the plane lost power five meters from the hand-launch and landed into the cotton again. No damage. Recharged battery but did not fly again, since I did not like the look of the aileron seams.
Advantages:
On a weak engine - a VERY easy plane, simple to fly, gentle turns, responds quickly to throttle. Flew most of the time on well below half-throttle, took off on 3/4 throttle (when battery was charged). Simple to build. Looks VERY nice, close up.
Disadvantages:
Disgustingly bad aluminum parts. I wish I did not use the aluminum spars on my Bf. So-so wood parts. VERY WEAK motor-mount area, needs major strengthening.
Suggestions:
1. Add lines along fuselage for the location of the strength spars. Yes - it will look slightly less Bf-109. On the other hand, it does not look TOO scale, anyway.
2. Please please please strengthen the motor-mount area.
3. Please please please use steel (aileron pushrods) and carbon or steel strengthening spars. The aluminum is not worth the weight.
4. I am not sure whether the Bf-109 can be given a landing gear safely, but I would have liked to see some landing gear. I was afraid to land it on dirt and pebbles.
Setup:
The setep used was a cheap Chinese everything:
Motor: eBay color4way BL 2208-17 (1100Kv, 30A, 38g)
Battery: Dynam 3S1P 10C 1250mAh
ESC: Who-The-Hell-Knows 30A w/BEC
Receiver: Feigao 72MHz
Servos: Three 9gm Tower Pro blue thingies
Kit Contents:
The plane and its EPP components are well made, precise and clean. The same can be said for the lexan canopy and the plastic horns and pushrod tubes. The wooden bits (in the Bf-109 it is the motor mount) are made of bad and very brittle wood. This is, however, something one can live with. The components that are really bad are the aluminum strengthening spars (about which much later) and the aileron pushrods.
Build Process:
The build is quite simple. The only difficult bit is digging in the servos, especially since the bottom servo (ailerons) and the top rear servo (rudder) meet in the middle, leaving the aileron servo a bit too far out of the plane, requiring some wing scraping.
The annoying bit are the wing and fuselage strengthening spars - made of soft aluminum, they bend and acquire a semi-circular shape if pushed in with pressure along their length. Very annoying. I built the Bf-109 with the aluminum spars, but when building a (related) Pitts, we ditched the aluminum spars for the wings and used a carbon rod. In fact - carbon rods are highly suggested for all strengthening spars.
I decided NOT to emplace the canopy until after a few flights, mainly because the Chinese blue servos are such incredible trash that to get three working servos, I went through six servos in total. Haven't the Jewish people suffered enough?
The provided aluminum aileron pushrods are (a) way too soft and (b) way too short. I ditched them and made steel pushrods.
The ESC was installed as suggested. The Rx was "bolted" on the right side of the fuselage (In my opinion, there is NOT enough space under the canopy for the Rx and two servos) and the battery (since it was temporary) was "bolted" on the left side of the fuselage. The bolt-on was using two wooden planks and a plastic bands.
CG was as recommended.
First Flight:
Hand-launch and a slow lazy flight (I over-propped, using a 10x4.7SF). The plane was NOT well trimmed and I was not sure of the setup or battery, so after a very short, slow, gentle (with a marked drop of the right wing (my fault for mis-aligning the servos, probably), I landed it into a patch of planta genista. The plane promptly cartwheeled and the fuselage BROKE in two places (photographs will follow separately) - right behind the motor assembly (the entire motor section came off and right behind the ESC emplacement. The energy of of the crash was VERY low, yet the breaks were major. The execrable aluminum spars simply bent, providing the fuselage with a very attractive flat S-shape along the length axis. I hand-slapped them into shape, cursing aluminum in general and this example in specificity.
Fixes:
Fixing the plane was done so as to strengthen the entire motor mount area. Three 2mm by 12mm carbon strips were inserted in the top nose section and one
5mm x 15mm in the bottom nose section. The insertions were then CA'd and kicked.
Second, Third, Fourth Flights:
Replaced the prop with an APC 9x4E. Same setup otherwise. Second flight: used to trip plane and cartwheel in a cotton field. No damage, but fixed the trim problems (wrongly! see later). Third flight: Gentle and docile flight, flew for three-four minutes, then switched off motor and glided into the cotton. Very simple and docile flight, no damage on landing.
I did not recharge the battery between the flights - on the fourth flight the plane lost power five meters from the hand-launch and landed into the cotton again. No damage. Recharged battery but did not fly again, since I did not like the look of the aileron seams.
Advantages:
On a weak engine - a VERY easy plane, simple to fly, gentle turns, responds quickly to throttle. Flew most of the time on well below half-throttle, took off on 3/4 throttle (when battery was charged). Simple to build. Looks VERY nice, close up.
Disadvantages:
Disgustingly bad aluminum parts. I wish I did not use the aluminum spars on my Bf. So-so wood parts. VERY WEAK motor-mount area, needs major strengthening.
Suggestions:
1. Add lines along fuselage for the location of the strength spars. Yes - it will look slightly less Bf-109. On the other hand, it does not look TOO scale, anyway.
2. Please please please strengthen the motor-mount area.
3. Please please please use steel (aileron pushrods) and carbon or steel strengthening spars. The aluminum is not worth the weight.
4. I am not sure whether the Bf-109 can be given a landing gear safely, but I would have liked to see some landing gear. I was afraid to land it on dirt and pebbles.