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FT Tiny Trainer (Mighty Mini)
- Thread starter fliteadmin
- Start date
Is there some sort of rule of thumb for comparing props. He was going to use a 7060 which you said was too much but you suggested that a 8 x 3.8 would be all right. It makes sense that the 7060 has more pitch but does that negate the fact that the prop is longer?
I recently overproped my Blue Wonder (or similar clone). Haven't killed it yet but the 8x6SF on 3S was definitely too much and the motor overheated and drew 9A (too much).
A 9x4.7SF on 2S only drew 5.3A and the thrust as measured by holding it in my hand may have been acceptable.
I was finally happiest with a 7x5SF on 3S which drew 6.2A.
These were on my Bloody Wonder MKIII
Any knowledge will be absorbed,
Thanks, LooseBruce
I recently overproped my Blue Wonder (or similar clone). Haven't killed it yet but the 8x6SF on 3S was definitely too much and the motor overheated and drew 9A (too much).
A 9x4.7SF on 2S only drew 5.3A and the thrust as measured by holding it in my hand may have been acceptable.
I was finally happiest with a 7x5SF on 3S which drew 6.2A.
These were on my Bloody Wonder MKIII
Any knowledge will be absorbed,
Thanks, LooseBruce
Nah, it's 1700kv I been using the same set up on my scaled down versa wing (30" wingspan) with well over 100 flights and motor never gets hot. There are different kv rating for the same cf2805 which all use different props. I will be using a gws7060 not a APC 7x6
Here is a link to the specs for the motor i am talking about. http://www.headsuphobby.com/Emax-CF2805-1700kv-Outrunner-Brushless-Motor-H-445.htm
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I am using a 7x6 prop on a 3s with this motor, it is a great combo! I don't have a watt meter but the motor is never to warm. On the hobbyking site people reported using a 7x6 prop without exceeding 7.5A.
This motor is also working great on a 10x4.5 prop when using a 2s lipo, it's really nice for slow flights on the tiny trainer.
This motor is also working great on a 10x4.5 prop when using a 2s lipo, it's really nice for slow flights on the tiny trainer.
Check out Winglet's article and his 9g server placement recommendations: http://flitetest.com/articles/tiny-trainer-a-little-airplane-to-love
Excerpt from his article:
"Okay, just a little about my build. My airplane is basically completely stock. The most notable exception are the servos mounted on the outside of the fuselage near the tail, rather than inside the airplane under the wing. I would encourage everyone to make this simple modification to avoid adding a ton of weight to the tail to reach the correct CG. The TT builds extremely nose heavy. Also....Josh called for 5 gram servos. I went ahead and used 9's because I needed the weight. With a 850mah battery my CG is perfect. No weight added anywhere. "
Dunno about that. I've got a pair of 9g in mine. Just needed to offset them from each other because they won't go in aligned. one is resting on the fuse floor, the other is almost at the top of the servo bay, but they happily coexist.
That and perhaps I skimped on the glue in the tail, but my powered version came up almost spot-on with a 2s500 under the pod. The glider nose need a bit of nose weight, but it also lacked a motor.
That and perhaps I skimped on the glue in the tail, but my powered version came up almost spot-on with a 2s500 under the pod. The glider nose need a bit of nose weight, but it also lacked a motor.
Good point. I did at some point attempt to offset them but aborted due to how fiddly it was. Don't think I would ever have been able to glue them in precisely the right location - mainly thinking about the push rods and how they are z-bent on both ends. But, yeah, that could have been a non-issue if I had used linkage stoppers for the rudder/elevator control horns, instead of z-bending. It would however not change the fact that it's very very fiddly to try and glue the 9G servos offset in that tiny little space 
Maybe I'm just not good enough at building yet.
Maybe I'm just not good enough at building yet.
"Good" is a relative term. You're almost certainly better than you were and unless you stop building, you will be even better some day
Yeah, they were fiddly for the dry-fit, but mostly because they weren't tacked down. When it came time to install the servos, I cleared the bay, and installed only the lower one. Once the glue set, I disconnected from the servo tester and moved that servo horn as far aft as it would turn. Then I had plenty of space to install and center the other servo. (if you're not installing these servos with the servo tester plugged in, you're making it harder on yourself to center the surfaces).
. . . And if you think that's fiddly, I've got a hotliner with 4 9g servos, ESC, RX and lighting harness in about the same space as the TT's servo bay, with the front half of the bay covered by the wing mount
Suffice it to say, I hope I never have to swap out an aileron servo!
Yeah, they were fiddly for the dry-fit, but mostly because they weren't tacked down. When it came time to install the servos, I cleared the bay, and installed only the lower one. Once the glue set, I disconnected from the servo tester and moved that servo horn as far aft as it would turn. Then I had plenty of space to install and center the other servo. (if you're not installing these servos with the servo tester plugged in, you're making it harder on yourself to center the surfaces).
. . . And if you think that's fiddly, I've got a hotliner with 4 9g servos, ESC, RX and lighting harness in about the same space as the TT's servo bay, with the front half of the bay covered by the wing mount
Suffice it to say, I hope I never have to swap out an aileron servo!
You aren't the only one. Many, if not most people have found it to be nose heavy.
Since the TT was my first plane ever, scratch-built or otherwise. I took the only solution I knew at the time and added 2 pennies to the tail in addition to the edge reinforcements.
Now that it has been a few months, the most common remedy is to relocate the servos to the tail. This goes a long way in ensuring good balance.
Other options include adjusting the wing a couple millimeters forward, and reinforcing the leading edges of the tail with hot glue.
Beefing up the tail skid helps too. After I added landing gear to my TT, I beefed up the tail skid with a piece of bbq skewer reinforced with a small piece of flag stick wire. Adding a tailwheel would also be an alternative.
If your flying fields tend to be a little more breezy, or you like to fly faster, don't be afraid to add a bit of weight. It will help it cut the wind better at the cost of a bit of efficiency.
Since the TT was my first plane ever, scratch-built or otherwise. I took the only solution I knew at the time and added 2 pennies to the tail in addition to the edge reinforcements.
Now that it has been a few months, the most common remedy is to relocate the servos to the tail. This goes a long way in ensuring good balance.
Other options include adjusting the wing a couple millimeters forward, and reinforcing the leading edges of the tail with hot glue.
Beefing up the tail skid helps too. After I added landing gear to my TT, I beefed up the tail skid with a piece of bbq skewer reinforced with a small piece of flag stick wire. Adding a tailwheel would also be an alternative.
If your flying fields tend to be a little more breezy, or you like to fly faster, don't be afraid to add a bit of weight. It will help it cut the wind better at the cost of a bit of efficiency.
My TT made a patriotic appearance last evening at out family gathering. It was pulling three 30' streamers of red, white, and blue. One on each wing tip and the center one from the horizontal stabilizer. Due to some repairing that I need to do, I had to power it with my emax BL2215/25 spinning a 9x3.8SF on a 3s 1800 battery. I got a good 20 minutes of flying out of it. All of the extra drag kept the tail from yawing to much and really made for some very relaxing flying, especially since that was the first time I have flown in front of more than one or two other people.
Second flight attempt was a winner today! I originally had the nose-heavy problem as many others do so I tried putting the battery on top of the wing. I don't know if it was just that or because I'm a newbie pilot, but I only got about 100 feet from me before it bit the dust. Broke the prop, but nothing else. I took it home and started researching mods to this awesome little airplane. I did the servo relocation to the tail and although it's not as pretty, it works really well! I also moved my massive clunky old receiver back under the rear wing stick. Now, she is balanced out beautifully and floats like a butterfly. It's a little squirrelly in the breeze, but I'll be doing a little reinforcement here and there so hopefully with the added weight, she'll cut through the wind a little better. Thanks Flite Test for getting me into airplanes! I love it!
