Build, learn, repeat...

[Jeffo]

Full disclosure: New to the hobby, haven’t even sent anything into the air yet!

Since the weather is crap where I am (Ontario, Canada) I’ve building up a small Air Force. I figure I’m likely to destroy at least a few in the beginning, so why not stock up?! I have a tiny trainer and mini scout built and ready to go (I think!). In various states of construction I have a sparrow, sea otter, and long ez. I am aware the latter two are not beginner planes, but I’m stuck in build mode, and they seem interesting. I keep ending up with questions that owners of these models will likely be able to answer. So here we go...

After installing motor/esc in the sparrow it is insanely tail heavy. Does it normally take a ton of weight in the nose to balance, and what is the best thing to use?

I have the sea otter mostly completed, but am wondering what motor could be used instead of the flight test power pack. They’re a little too pricey for me.

 

[FDS]

The battery is the best thing to use to counter balance the motor in rear mounted designs.
Its always a good idea to build new planes, especially in winter. If you don’t fancy the FT power packs just look at the two figures of the motor, the first one e.g. 2212, is the motor size, then the second is the KV, which is the number of turns per volt expressed in thousands. Take those, then search for a motor that matches, check the peak current and find an ESC with a bit above that as it’s peak current, for example if your motor pulls 25A then a 30A esc is a good idea. All the power packs are too expensive here as well. Bulk buy the cheap plastic gear servos like the Tower hobbies or Hobbyking ones, get some Y leads and servo extensions then you have what you need.

 

[Merv]

........I figure I’m likely to destroy at least a few in the beginning, so why not stock up?! ......After installing motor/esc in the sparrow it is insanely tail heavy.......I have the sea otter mostly completed, but am wondering what motor could be used instead of the flight test power pack......

I also stock up on planes in the winter. I’d recommend building several of the trainer of your choice. I have several laying on the bench ready to accept the guts of my latest carnage.

In the sparrow, have you install the battery yet? All planes will be tail heavy with out the battery. I have needed to extend the nose on several plane to get them to balance.

Regarding a different motor, look for one with similar Kv & watts. Kv & prop size is also a good indicator.

 

[Jeffo]

I also stock up on planes in the winter. I’d recommend building several of the trainer of your choice. I have several laying on the bench ready to accept the guts of my latest carnage.

In the sparrow, have you install the battery yet? All planes will be tail heavy with out the battery. I have needed to extend the nose on several plane to get them to balance.

Regarding a different motor, look for one with similar Kv & watts. Kv & prop size is also a good indicator.

I did install a 650mah 2s in the nose, which obviously didn’t help at all. I read somewhere that was a reasonable size for the TT, so that’s all I have on hand. Seems kinda small now, though.

 

[Merv]

I did install a 650mah 2s in the nose....

Sounds like you need a larger battery or need to move it forward, may need a longer nose.

I set the plane on a balance stand and move things around until I can get it to balance.

 

[FDS]

Look at the FT store listing for the speedbuild kit, that gives the recommendation for the battery.
For the sparrow a 3s 850mah pack of about 80g is recommended. Many of the minis use a similar pack, the 2s TT is an exception as it is designed to fly slower and it has a fairly large wingspan compared to something like the Sparrow.
As above, put the plane on the CG points, then move the battery about until it sits just a touch nose down. You can use bags of pennies to stand in for a battery, get it to balance then weigh the pennies and look for a battery close in weight to that.

 

[Jeffo]

Yes, the card that came with the kit says 800mah 3s. Don’t think that will be enough to balance it out though. Good idea with pennies! Will lengthening the nose change the CofG location?

 

[FDS]

No, but it will increase the leverage acting on the tail. If you can put the motor a bit further toward then that will help. If you have 9g servos in the back that won’t help either.
You are better off using more battery weight than running ballast. See how much more weight you need to get it balanced. Rushing to chop it up will result in a poor flier.
When building low weight should be your priority, watch out for adding more weight at the extremes of the airframe, as they will affect balance more severely. Don’t put too much hot glue on tails and keep rear mounted motors as light as you can.

 

[Merv]

.....Will lengthening the nose change the CofG location?

It depends on what you are asking.
Making the nose longer & moving the battery forward will move the CG forward.
The place where the plane should balance will not change.

 

[FDS]

Yeah, that’s an important distinction between the balance point and C of G. Easy to forget, as I proved above!

 

[Jeffo]

Haha yes, I meant balance point.

 

[Jeffo]

Using the “penny bag”, looks like I need 107g extra, without a battery, to balance. An 850mah 3s weighs 70g. Suggestions?

 

[Jeffo]

Ok, 1050mah 3s comes in at 97g, plus the receiver at 7g, that oughta do it 🙂

 

[RustySocket]

The battery is the best thing to use to counter balance the motor in rear mounted designs.
Its always a good idea to build new planes, especially in winter. If you don’t fancy the FT power packs just look at the two figures of the motor, the first one e.g. 2212, is the motor size, then the second is the KV, which is the number of turns per volt expressed in thousands. Take those, then search for a motor that matches, check the peak current and find an ESC with a bit above that as it’s peak current, for example if your motor pulls 25A then a 30A esc is a good idea. All the power packs are too expensive here as well. Bulk buy the cheap plastic gear servos like the Tower hobbies or Hobbyking ones, get some Y leads and servo extensions then you have what you need.

@FDS Old school nitro flyer here and new to the electric world. Thanks for your short summary on how to evaluate the motor. The only thing I might add is to look at the weight too and make sure it's in the ballpark to what the plans call for. I purchased a combo from FT for my first (a Baby Blender) but I was buying things like servos, and extensions that I didn't really need in the process. I figured I'd do it once to get something that I didn't have to guess about. But going forward I will be looking into other sources and piece things together on the cheap.

@Jeffo your on the right track having a fleet built and ready to go. Your skills will come and you will be flying advanced designs in no time at all. I love to see the new guys to the RC hobby actually building planes from plans rather than buying the current Horizon ARF. When you build the plane yourself, you know how to fix it when you break it. And you will break it.... Enjoy.

 

[Jeffo]

So I’ve got 3 planes ready to go, it’s still miserable outside, and I have a stack of foam board sheets asking to be turned into airplanes. Enter the 80% old fogey. The full size calls for a B power pack. Should I stick with that, or go a bit smaller?

 

[The Hangar]

@Jeffo on my sparrow I stuck a 1000 mah 3s in mine and when that wasn’t enough, I put a 1500 mah 2s in the nose. I was using 9g servos and had them back in the fuse a little. It flew kinda heavy, but it was ok.

 

[Jeffo]

Along with the 80% old fogey, I built an 80% simple cub. Planning on using the same motor/esc for both. If the motor is a 1000kv with a 1045 prop, is there any chance of the 30a esc getting catastrophically hot if I put it inside the swappable pod? Not much airflow in the cub, so not sure if that could become an issue. I have no idea if that motor is suitable for either plane, but I figured at $15 for motor/esc/props, I’d throw it in and see what happens!

 

[The Hangar]

Along with the 80% old fogey, I built an 80% simple cub. Planning on using the same motor/esc for both. If the motor is a 1000kv with a 1045 prop, is there any chance of the 30a esc getting catastrophically hot if I put it inside the swappable pod? Not much airflow in the cub, so not sure if that could become an issue. I have no idea if that motor is suitable for either plane, but I figured at $15 for motor/esc/props, I’d throw it in and see what happens!

That would fly a 100% fogey or scout just fine. Actually I’d recommend building a full sized old fogey or old speedster as they fly really really slow - slower than a mi I actually since both will weigh similarly due to the same electronic setup, but the larger size will mean more wing area and thus will fly slower. The old speedster was the first plane I was able to successfully fly by myself.

 

[Jeffo]

I was actually considering the speedster, but given the name thought maybe I should choose something slower! I built at 80% to keep the size down a bit, as I’m running out of room to store these things. I’m sure once the decent weather arrives my fleet will diminish quickly!

 

[BATTLEAXE]

Along with the 80% old fogey, I built an 80% simple cub. Planning on using the same motor/esc for both. If the motor is a 1000kv with a 1045 prop, is there any chance of the 30a esc getting catastrophically hot if I put it inside the swappable pod? Not much airflow in the cub, so not sure if that could become an issue. I have no idea if that motor is suitable for either plane, but I figured at $15 for motor/esc/props, I’d throw it in and see what happens!

If you are running your planes downscaled to 80% you will easily be able to spin a 8-9" prop in the same pitch range, thus reducing the amps required to spin them, keeping your ESC cooler in the process. That's actually a good match doing the b pack on the downscaled planes. It will fly like the full size on the C pack