Projects 'nother question or two???????

Loopy

Active Member
I know there is a "sticky" that I should be able to use to arrive at what my needs are, but I have a mental block when it comes to electrics. As I have mentioned elsewhere, I am planning to build a WACO UPF-7. Expected to weigh 8#. 56" wingspan. The original plans called for a 70 four stroke engine. I need help deciding on what size electric motor, escapement and servos to buy. There seems to be a plethora of options. Altitude Hobbies has suggested a Leopard 5055-650 or 550 motor with an 80 watt escapement. Any other suggestions from the experienced members is appreciated. :thankyou: :anyone:
 

Smoggie

Well-Known Member
Those recommendations look good with i'm guessing a 4S battery for the 650Kv motor or 5S for the 550Kv and a 15" prop? If you want to look at other motor brands anything around the same weight and Kv should work. By the way ESC stands for Electronic Speed Controller. Escapements were things found in RC planes 60 or 70 years ago :)

For servos, a lot depends on budget, you don't really need anything too fancy. You can go down a size of servo generally from what these old plans call for, so you could use mini instead of standard size because servos perform way better than they used to. I'd go for mounting an individual (mini) servo for each aileron in the wing rather than the single servo with linkages that was typical 'back in the day'. For the rudder and elevator a standard size as per the plan would work fine, or minis to save a few grams.
 
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Loopy

Active Member
Those recommendations look good with i'm guessing a 4S battery for the 650Kv motor or 5S for the 550Kv and a 15" prop? If you want to look at other motor brands anything around the same weight and Kv should work. By the way ESC stands for Electronic Speed Controller. Escapements were things found in RC planes 60 or 70 years ago :)

For servos, a lot depends on budget, you don't really need anything too fancy. You can go down a size of servo generally from what these old plans call for, so you could use mini instead of standard size because servos perform way better than they used to. I'd go for mounting an individual (mini) servo for each aileron in the wing rather than the single servo with linkages that was typical 'back in the day'. For the rudder and elevator a standard size as per the plan would work fine, or minis to save a few grams.
Well, H--L, I am OLD school. A really old geezer. :pride:I remember the rubber band 1 click 2 click system. IF you can call that a system.

Should I be concerned re: the voltage of the servo? There is no servo recommendation. I have found that a digital is superior to analog and metal gears preferable to plastic. :thankyou:
 

RandyDSok

Well-Known Member
Mostly this will be an FYI and not a recommendation as I think the motor you were suggested is probably just fine for the job. Later I will link to a company that produces custom wound motors that I really do like, but they do come at a price.

The motor's name is also an indication of it's size... but companies will use two different methods to name with... On the Leopard I believe they are using the outer dimensions of the case itself ( although I'm not sure where exactly they are getting the 55 from unless the diagram shown is the wrong one )... So the 5055 should be the outer dimensions of the "can" ... ie 50mm diameter width and somewhere they are measuring 55mm long.

The other method you'll see are the approx. measurements of the stator within the can. I prefer this later method since the thickness of the can material and the gap between the can and stator can vary, but that is still a subjective opinion. Either way, just pay attention to which measurement style the model you are looking at is using when comparing different motors.

The company I mentioned, uses the stator size to name their motors. Their closest equivalent to the one you mentioned is going to be something in their DM-4315 class of motors. The company name is Subsonic LLC and they sell Motrofly motors that are as mentioned, custom wound in a variety of kv's. In fact, you can call them and even get a motor wound to your own specs if you wish. The DM-4315 series has 16 available kv's to select from once you are adding them to your cart, their example spec sheet only lists about 6-8 examples of what you can expect out of a motor given a certain kv, voltage and prop size.

You can find them here https://subsonicplanes.com/Home_Page.html ... They also welcome calls or emails for any questions you may have.
 

Loopy

Active Member
Mostly this will be an FYI and not a recommendation as I think the motor you were suggested is probably just fine for the job. Later I will link to a company that produces custom wound motors that I really do like, but they do come at a price.

The motor's name is also an indication of it's size... but companies will use two different methods to name with... On the Leopard I believe they are using the outer dimensions of the case itself ( although I'm not sure where exactly they are getting the 55 from unless the diagram shown is the wrong one )... So the 5055 should be the outer dimensions of the "can" ... ie 50mm diameter width and somewhere they are measuring 55mm long.

The other method you'll see are the approx. measurements of the stator within the can. I prefer this later method since the thickness of the can material and the gap between the can and stator can vary, but that is still a subjective opinion. Either way, just pay attention to which measurement style the model you are looking at is using when comparing different motors.

The company I mentioned, uses the stator size to name their motors. Their closest equivalent to the one you mentioned is going to be something in their DM-4315 class of motors. The company name is Subsonic LLC and they sell Motrofly motors that are as mentioned, custom wound in a variety of kv's. In fact, you can call them and even get a motor wound to your own specs if you wish. The DM-4315 series has 16 available kv's to select from once you are adding them to your cart, their example spec sheet only lists about 6-8 examples of what you can expect out of a motor given a certain kv, voltage and prop size.

You can find them here https://subsonicplanes.com/Home_Page.html ... They also welcome calls or emails for any questions you may have.
Holy Cow!!!!! Can't afford those prices!!!:dizzy::dizzy::thankyou:
 

RandyDSok

Well-Known Member
Holy Cow!!!!! Can't afford those prices!!!:dizzy::dizzy::thankyou:

Yeah, custom wound motors aren't cheap. There are reasons for it, the motor I have from them ( a DM-2820 ) has the same power class as an E-Flight Power 46 only mine weighs in at 152g instead of the 290g that the Power 46 comes in at. That is an extreme example since other higher end brands ( Hacker and Scorpion for example ) were more closely related in power/weight to the Motrofly motors when they had a similarly classed motor. The specs shown on the one you mentioned, were in the same ballpark so if it's a good brand with a decent reputation for support, I'd go with that one as well.
 

Fly-n-Low

Active Member
I like Hitech servos... I have them on my heli and my 3D plane. As said, metal gear digital are the way if you can to spend the money. Randy and Smoggie are on point!

Randy, those motors!!! :hdbng:

One thing though, a biplane at 56" is like a mono at 80" or so as far as power goes. Some one correct me if I am wrong.
 

RandyDSok

Well-Known Member
One thing though, a biplane at 56" is like a mono at 80" or so as far as power goes. Some one correct me if I am wrong.

Not wrong.... but incomplete but a percentage is often used to generalize or approximate the differences. To get more exact you would look at the total wing area... not just the wingspan difference. Some additional factors which are starting to get into the weeds are things like the differences in airfoil shape efficiencies.... Then there is the air density vs size of the aircraft discussion, in short a smaller aircraft is affected more by the air, wind etc than a larger one is. I'm sure an aircraft engineer can add even more things that should be considered... but I am most certainly not one of those.

I think for our needs... just comparing total wing areas between the two models... is probably close enough for a generalization.
 

Loopy

Active Member
It just blows me away the amount of knowledge you guys have. You all must have been doing this for decades!!! :dizzy: :dizzy:
 

RandyDSok

Well-Known Member
I've probably have just under a decade of actually being "in" the hobby. I do happen to research a lot on the things that interest me. I'd attribute most of that to my Dad, whom also got me started when I was young and saw I had an interest in it. He started early on in the hobby before there were proportional radios even, in fact, I recall a few stories about their free flight models as well. Later, my Dad and an uncle would even salvage radios out of cars and then convert them over for use as single channel pulse RC radios. As I was growing up, I'd always go out to the garage when Dad was working on something and of course that included his RC airplane collection. I'm sure I bugged the heck out of him with a million questions while he was doing something to them. Things just evolved from there.
 

Loopy

Active Member
I've probably have just under a decade of actually being "in" the hobby. I do happen to research a lot on the things that interest me. I'd attribute most of that to my Dad, whom also got me started when I was young and saw I had an interest in it. He started early on in the hobby before there were proportional radios even, in fact, I recall a few stories about their free flight models as well. Later, my Dad and an uncle would even salvage radios out of cars and then convert them over for use as single channel pulse RC radios. As I was growing up, I'd always go out to the garage when Dad was working on something and of course that included his RC airplane collection. I'm sure I bugged the heck out of him with a million questions while he was doing something to them. Things just evolved from there.
And you know, your dad probably appreciated having you there. I too built model air planes from a young age back during WWII. Balsa then was just really crappy. They were rubber powered. I remember my first successful flight. I was thrilled!!!! My first powered free flight was an .049 glo. I put WAAAY too much fuel in it and it flew almost to the moon. One successful flight only.:grief: I got into control line during the early to mid 60's. I had so many trophies that finally I just junked them. No place to store them. I still have my last scratch built Semi-scale F-111 hanging on my garage wall. Got into motorcycling in 66-67 and didn't have time for modeling after that. RC was just getting a good start about that time. I just got serious about RC last winter, so that's why I need so much help with the electronics. I really appreciate all the help and advice from this forum.:arms::arms:
 

Loopy

Active Member
Here's a "nother question!!!! What is the best glue for models nowadays? In the old days we used Ambroid and Hoby Poxy. It seems to me that most any good wood glue would suffice, such as TiteBond or Elmer's and any 2 part epoxy for the extreme jointing.
 

RandyDSok

Well-Known Member
I'd say TiteBond over the Elmer's.... but I may be biased and it's not based on any bad experiences I've had in the past with Elmer's ( the actual wood glues themselves, not the general white one ). I'm pretty sure that today, the good modern CA's ( of various thinness/thickness depending on the application needed ) are probably better for most building needs, I'm uncertain of what brand to suggest since it's been a long time since I've built or repaired anything. I'd also still use a good epoxy for things such as landing gear installations or firewalls... on the firewall application probably only for a nitro build since that will protect the wood against getting soaked, same problem on suggesting a brand on this since I haven't used any in so long.
 
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