Confused by a Lowbo Plan - motor choice

[Eifion Herbert]

So I'm building the Lowbo from the plan in RCMW in the summer.

See here

The description here stipulates a 2228 Turingy motor, well there's no such thing, but there are 2822 size motors, so I assume this to be a typo. However, all motors of that size come up around 80 - 90 Watts max, which if my model comes in at the expected 1.75 lb mark is only going to get me around 50 Watts per pound.

The actual plan itself stipulates a 2238 size motor, can't find anything in that size either, so I've given up trying to work out what was actually used on the prototype. Assuming I would like 100 - 120 Watts per pound for reasonable performance I'm looking for deliver something around the 180 - 200 Watts mark, with a mediumish Kv rating.

I'm looking at these three as possible options - am I in the right ballpark?

Motor 1

Motor 2

Motor 3

Edited By Steve Hargreaves - Moderator on 17/11/2015 15:57:31

[Tomtom39]

Hello,

I've built one of these some while ago (my had one of the E-Flite park 480 motors in it - vaguely remember approx 220W on 3S Lipo with 12X6 APCE and a 35A Esc -one I had left over from another project) . It flew very well

Your middle choice from HK seems about right .

Best of luck with it

[Steve Hargreaves - Moderator]

Eifon, you might like to take a look here for advise on how to post links in your threads....

I think any of the motors will fly the plane but I would suggest going for a kv around the 1100 mark if you can....that should give you around 200 watts on an 8 or 9" propeller.....the description of the model suggests a 7x5 prop which seems very small for a 42" span model. What sort of prop clearance do you have? Might it be that a small prop is required to clear the ground I wonder.....

[Steve Hargreaves - Moderator]

PS...I assume you plan on using a 3S battery by the way......if not we'll need to take another look at the kv figure....

[ron evans]

Hi Eifion

You may already be aware, but just to clarify, some manufactures stated numbers refer to the internal stator size, so a 2228 could well be 28 38 on the outside. Some Turnigy and Emax motors are like this but not all. They don't make it easy do they.

Good luck

Ron

Edited By ron evans on 17/11/2015 16:41:51

[Eifion Herbert]

Thanks for tidying up my links Steve, will try to remember it doesn't automatically parse URLs.

The prop seems small to me too, there's plenty of clearance as far as I can see, the motor axle sits a good eight inches above the ground at the moment, make that nine by the time I fit the wheels. Even allowing for the tail to come up there's still plenty of room for an 8 or 9" diameter prop I'd have thought.

It's good to know I'm not a million miles off in my selections.

I'll be running it on a 3S, plan says 1500 mAh, going to try to sneak in a 2200 for longer flight times if the weight doesn't become too much of an issue.

[Tomtom39]

The 2200 mAh was the battery I used but switched over to a 2650mAh (3s) with no issues .

[PatMc]

Judging be the photo of the original, there looks likely to be plenty of room for the motor. If that is the case I'd wait until the model was about complete, see how much weight in the nose/battery bay area would be needed to achieve the cg, then decide on motor & battery. I'd be thinking in terms of an 8" or 9" prop with a 900 - 1000kv motor.

[Eifion Herbert]

Posted by PatMc on 18/11/2015 11:40:19:

wait until the model was about complete, see how much weight in the nose/battery bay area would be needed to achieve the cg, then decide on motor & battery.

The thing is to move forward with the build the next thing I need to do is glue in F1, and I'd rather fit the captive nuts and the motor mount to it before it's inside the fuse, so I need to choose now. Also as my building style can most kindly be described as "agricultural", I'm not holding out much hope of coming in under weight!

[PatMc]

I was going to suggest that if you need to add nose weight a heavier motor with a 4mm or 5mm shaft would be more robust & run cooler at all throttle settings.
This E-Max for example takes my 33 oz glider up in a vertical climb to 200 mtrs (660 ft) within 30 secs using 250W power. The prop is a 9 x 5 folder but it's on a spinner that extends it to 9.75", a fixed 9x6 would probably take about the same or a little less power but I'd think certainly enough for a very sprightly performance from the Lowbo.

[Tony Wright 2]

There is an email address at the end of the article ,did you not think to contact the designer ? Everything re motor prop etc (7x6) is corect

tomtom 39 states he built a lowbo somewhile back ? The prototype was only built in June 2015 ?

Lets get your facts right .Tony Wright designer...

[Tony Wright 2]

The silence is deafening !!!!!!!!!!!!!!!!!!!!

[Anthony Wright 3]

Hello did you ever fly the lowbo ?