Scale down plans for 11** motor.

[Madewthrealchz]

Hi. I'm curious to know at about what size plans should be scaled down to if I were to power them with an 1100 size motor and say a 3" prop. I'm thinking about maybe a small slow flyer for small parks. Perhaps scaling down the Mini Pietenpol or Tiny Trainer. Or even scaling the Simple Cub or Old Fogey to something that size. Right now it's a thought experiment but I'm curious to see if you guys think it's easily doable or if the scaling creates some issues.

 

[ElectriSean]

It pretty much boils down to the power to weight ratio. Get the thrust data from the recommended power pack for the plane, as well as for the power system you want to use and see how they compare. Just remember that scaling down won't directly correlate to weight reduction as the thickness of the foam board doesn't change.

 

[Morgan]

I hav never built somthing this small before but my guess is About 45% if you want a slow flyer .if you are only running on 2s you might to go a little smaller.

 

[Madewthrealchz]

It pretty much boils down to the power to weight ratio. Get the thrust data from the recommended power pack for the plane, as well as for the power system you want to use and see how they compare. Just remember that scaling down won't directly correlate to weight reduction as the thickness of the foam board doesn't change.

Thanks for the feedback. I started scaling the Simple Cub down to 40% as a starting point. But in the process it has dawned on me that the thickness of the foam will remain constant so it's causing some readjustments in the way the plan goes. I have plenty of Readi-Board so I want to make a quick mock-up of the 40% to see how heavy the airframe is. Then I can compare it to the power system specs and see where that leaves me. Plus I just really enjoy building airframes. So if I have to do it a couple of times it'll be fine with me.

 

[Gazoo]

Thanks for the feedback. I started scaling the Simple Cub down to 40% as a starting point. But in the process it has dawned on me that the thickness of the foam will remain constant so it's causing some readjustments in the way the plan goes. I have plenty of Readi-Board so I want to make a quick mock-up of the 40% to see how heavy the airframe is. Then I can compare it to the power system specs and see where that leaves me. Plus I just really enjoy building airframes. So if I have to do it a couple of times it'll be fine with me.

Unless I'm mistaken, I believe that scaling down an airframe but keeping the foam the same thickness will result in a tail heavy airframe. This is because there is more mass aft the center of lift at the wing when the foam thickness increases. You may want to consider moving the servos forward so you don't have to add nose weight.

I have never scaled anything down so take it for what it's worth.

By the way, I like your attitude. I like to build more than fly sometimes.

 

[Mid7night]

I love this idea!

Keep in mind, as you scale things down, not only will you need to account for the constant thickness of foam, but you also will be allowed to reduce or remove certain features that may have been in the larger build for strength purposes. Like wing spars and power pod doublers ... as you scale down the mass scales down by the CUBE of the scale factor, so weight and the forces involved come down QUICKLY.

Be judicious with glue, only use parts that are NECESSARY to hold the plane together, and I think you'll have a winner. Definitely stick to 2S, and look closely at the Emax 1106-4500 that FT just put in their "Micro Twin" Power Pack H. I don't think you'll need a twin, but I think that motor warrants SERIOUS consideration ... ::hint:: ::hint::

 

[Madewthrealchz]

Well I gave it a try. A lot of considerations when scaling down this far. The obvious issue is having the thickness of the foam being the same as on the full size. It really requires modifying a lot of the plan. Also, I didn’t do any work on the power pod. Just wanted to see what the basic frame looked like. Gotta say. It’s damn adorable. Even if I never power it it’ll make a great chuck glider. I’m thinking this might be better at 50 or 55%. Here’s a picture of it next to my Mini Scout. Not a standard sized Scout, mind you. But a Mini Scout.

https://www.ebayphotogallery.com/zdjecia/z1035/10358067/big/3.jpg