Hacker Model Bf-109

[mixerfix]

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.

[MDreamer]

thats a REALLY good review. do you know how to upload photos?

[Boogle]

סקירה יפה, אבל תמונה שווה אלף מילים, אפשר לפחות תמונה של הכלי המוגמר?

נורא נחמד לקרוא את תרגום הגוגל של הסקירה לעברית במיוחד הקטע של מנוע על ההר (MOTOR MOUNT)

[mixerfix]

התמונות תצורפנה מאוחר יותר... העיפות דוהרת...

מרק

[mixerfix]

בחיי... איזה תרגום... לא להאמין. המטוס לא מתופח...

איכס...

מ

[mixerfix]

Added photographs

[yaron_k]

כל הכבוד על הסקירה הממצה.
אכין אחת שלי (לא באותה רמה - אני מודה) לגבי ה- SuperZoom XL המדהים של Hacker. - מתחרה ראוי ל- Telink YAK

ירון

[guyst]

סקירה יפה!
למה לא בעיברית..?

[yaron_k]

לבינתיים - עד שאואיל לשלוח את הסקירה שלי - הנה שתי סקירות מקיפות על דגם דומה , ועל הסופר זום 2 שנערכו ב-RC-GROUPS

http://www.rcgroups.com/forums/showthread.php?t=1246222,

http://www.rcgroups.com/forums/showthread.php?t=1280603


תהנו

[mixerfix]

למה לא עיברית - בעיקר משיקולי יעילות ומהירות הקלדה - אין לי אותיות עיבריות בלוח המקשים, ואני מקליד מזכרון.

מ

סקירה יפה!
למה לא בעיברית..?

[MDreamer]

אתה יודע שאתה יכול לשלב את התמונות בגוף המאמר? פשוט תעתיק את מיקום התמונה, לחץ על האיקון של ההר האפור על הרקע הצהוב ותדביק שם את הקישור.
האם אנגלית היא שפת אם שלך?

[mixerfix]

ירון - עכשיו אני אשמח לקחת, לחשמל ולבדוק את ה- Decathlon או את ה- El Bandito

אתה יכול לארגן?

מ

[mixerfix]

כן - אני יודע. אך במספר המועט של הצילומים שצילמתי, לא היה הכרח.

ולגבי שפה - מה זה שפת אם?

אתה יודע שאתה יכול לשלב את התמונות בגוף המאמר? פשוט תעתיק את מיקום התמונה, לחץ על האיקון של ההר האפור על הרקע הצהוב ותדביק שם את הקישור.
האם אנגלית היא שפת אם שלך?

נ.ב. אני לא שואל להכעיס - רוב האנשים לא לגמרי יודעים להגדיר שפת אם. או - אפילו - שפה.

מרק

[yaron_k]

כמובטח - מצ"ב הסקירה שלי על ה- ZOOM XL

אצלי האנגלית היא ממש (אבל ממש) לא שפת אם, אבל במקרה הזה אני מעוניין שהיבואן (גיא יצחקי) יעביר את ההמלצות לשיפור לחו"ל, ועל מנת להקל עליו - כתבתי באנגלית.

אז Here It Goes:

Attached is my review of building and flying the Hacker-Model Super Zoom XL.
First – I must state it is truly a great flaying model.
To demonstrate that – please refer to the following link to a short video-clip (Thanks to Omri Launger) demonstrating the hovering stability in a very high (12-15kt) wind:


Model design, building and material overall quality are very good, and far better than the well esteemed MS-Composit epp models.
Hits:
1. I especially liked the fuselage longerons – and the stiffening they provide – which makes the model fly very accurate compared to this brand of models.
2. The size – is also very good, as the large wing and the resulting low wing loading result in a very nice, effortless flying, and enable very mild usage of the throttle.
3. Another hit is the construction of the motor mount. Very smart and neat, yet a stiffening connection to the landing gear area is required – as described below

Yet – in order to surpass what I believe to be one of the leading EPP models to date – the TELINK YAK, I would recommend the following improvements:
First – for the setup I used (basic Chinese setup):
Motor: TGY AerodriveXp SK Series 28-26 1000Kv / 240
ESC: Otter 40A 2-3S Brushless ESC w/ 4A BEC (w/ G
Prop: TP Slow Fly propeller 11x3.8
Battery: ZIPPY Flightmax 1800mAh 3S1P 40C

Now – for my impressions and suggestions (have implemented most of the suggestions below with great success):

Structure:
1. Nose section appears to be too soft – suggest addition of two carbon strips bridging between the bottom support of the firewall, and the landing gear mount. This will prevent un desired flexing of this area in flight, and possible breaking on hard landings.

2. All control surfaces hinge line is prone to tear off very easily. Recommend addition of some segments of peel-ply or Kevlar cloth to be CA-glued on the tips of each control surface to reinforce it. I used CA hinges but they seem to be a little too rigid at the beginning.


3. Tail skid is to low – allowing the rudder to be damaged from the ground when landing/checking controls before flight. Suggest addition of a small flat segment of fiberglass / ABS to continue the bottom surface of the tail skid and serve as a leaf-spring tail support (I used 0.6 mm glass epoxy sheet).

Travel of controls:
1. Travel of ailerons and rudder is sufficient.

2. Travel of elevator is badly influenced by rudder horn and pushrod. Suggest rudder servo and rudder horn will be elevated by 15-20 mm upwards, and clearing a bigger opening in the rudder to allow elevator deflection to 50-55 degrees.

Flying:
1. Fuselage side surface is on the low side – hence requiring too much rudder for knife-edge flight - high angle relative to the ground and too much controls coupling. Suggest heightening the fuselage side profile by 10-15% to achieve larger lifting surface.

2. To reduce coupling – I mounted the battery relatively upfront, and above the fuselage longerons. Suggest a cavity shall be made in that place to direct modelers to the preferred battery location

[yaron_k]

ירון - עכשיו אני אשמח לקחת, לחשמל ולבדוק את ה- Decathlon או את ה- El Bandito

אתה יכול לארגן?

מ

אני בטוח שגיא ישמח
הוא מביא משלוח ראשון במחיר מיוחד - ואני כבר הזמנתי...

[guyst]

כמובטח - מצ"ב הסקירה שלי על ה- ZOOM XL

אצלי האנגלית היא ממש (אבל ממש) לא שפת אם, אבל במקרה הזה אני מעוניין שהיבואן (גיא יצחקי) יעביר את ההמלצות לשיפור לחו"ל, ועל מנת להקל עליו - כתבתי באנגלית.

אז Here It Goes:

Attached is my review of building and flying the Hacker-Model Super Zoom XL.
First – I must state it is truly a great flaying model.
To demonstrate that – please refer to the following link to a short video-clip (Thanks to Omri Launger) demonstrating the hovering stability in a very high (12-15kt) wind:
http://www.youtube.com/watch?v=UmxGFYrYznA

Model design, building and material overall quality are very good, and far better than the well esteemed MS-Composit epp models.
Hits:
1. I especially liked the fuselage longerons – and the stiffening they provide – which makes the model fly very accurate compared to this brand of models.
2. The size – is also very good, as the large wing and the resulting low wing loading result in a very nice, effortless flying, and enable very mild usage of the throttle.
3. Another hit is the construction of the motor mount. Very smart and neat, yet a stiffening connection to the landing gear area is required – as described below

Yet – in order to surpass what I believe to be one of the leading EPP models to date – the TELINK YAK, I would recommend the following improvements:
First – for the setup I used (basic Chinese setup):
Motor: TGY AerodriveXp SK Series 28-26 1000Kv / 240
ESC: Otter 40A 2-3S Brushless ESC w/ 4A BEC (w/ G
Prop: TP Slow Fly propeller 11x3.8
Battery: ZIPPY Flightmax 1800mAh 3S1P 40C

Now – for my impressions and suggestions (have implemented most of the suggestions below with great success):

Structure:
1. Nose section appears to be too soft – suggest addition of two carbon strips bridging between the bottom support of the firewall, and the landing gear mount. This will prevent un desired flexing of this area in flight, and possible breaking on hard landings.

2. All control surfaces hinge line is prone to tear off very easily. Recommend addition of some segments of peel-ply or Kevlar cloth to be CA-glued on the tips of each control surface to reinforce it. I used CA hinges but they seem to be a little too rigid at the beginning.


3. Tail skid is to low – allowing the rudder to be damaged from the ground when landing/checking controls before flight. Suggest addition of a small flat segment of fiberglass / ABS to continue the bottom surface of the tail skid and serve as a leaf-spring tail support (I used 0.6 mm glass epoxy sheet).

Travel of controls:
1. Travel of ailerons and rudder is sufficient.

2. Travel of elevator is badly influenced by rudder horn and pushrod. Suggest rudder servo and rudder horn will be elevated by 15-20 mm upwards, and clearing a bigger opening in the rudder to allow elevator deflection to 50-55 degrees.

Flying:
1. Fuselage side surface is on the low side – hence requiring too much rudder for knife-edge flight - high angle relative to the ground and too much controls coupling. Suggest heightening the fuselage side profile by 10-15% to achieve larger lifting surface.

2. To reduce coupling – I mounted the battery relatively upfront, and above the fuselage longerons. Suggest a cavity shall be made in that place to direct modelers to the preferred battery location

למה שלא תיפתח דף חדש? סקירה חדשה?

[mixerfix]

אם אני מביא ה- Decathlon הביתה, אני עובר לגור אצלך 10 דקות אחר-כך. אני, ה- Deca, ה- Tele, וה- UCD. תחושת בטן, אבל לא שגויה.

אני בטוח שגיא ישמח
הוא מביא משלוח ראשון במחיר מיוחד - ואני כבר הזמנתי...

[Boogle]

ירון אני עם גיא, אנא הכנס סקירה נפרדת

לא ידעתי שיש לך זמן לכתוב סקירות

[mixerfix]

Update to the Bf-109 review:

I had time to fly it again today. The setup was unchanged. One more observation on build and strengthening process - back of wing (where the wing is glued to the fuse) - needs more strength - I inserted two 2cm x 2cm carbon splices.

The plane would most definitely benefit from a landing gear of some sort. I landed it three or four times on asphalt today - all landings very light, but the feeling is uncomfortable.

As for fun - today the plane flew with a freshly charged battery and was very agile, somewhat wild on the ailerons and very snappy. LOTS of fun. Excellent value for the money, especially if you strengthen all the points during the initial build.

Marc