Choosing an airframe


The entire community runs off the knowledge of others, recommending things for each other, building things for each other, coding things for each other. As I am trying to get some code together for later release it came to me that the maths I'd been using to help an RC Groups thread would be spot on for us. I of course posted it but changing it regularly (thanks to new model planes being released) has meant the file has to be uploaded continually to the thread so here is its own blog post. I actually posted an older one on my first blog but as I've altered it somewhat.

The file is nothing special in itself it just collates information and shows the viability of an airframe mathematically (not physically). The maths evaluates the attributes of an airframe to a few existing experiences (the first 10) on how difficult they were to fly this gives values on the beginner safe planes (wing loading). Again advice dictated to motor recommendations, 90w/lb is a base touted value for flight, 100w/lb is claimed to be perfect for gentle flight maneuvers. Spare mass is the mass you can add without the airframe going over the specified beginner "safe" values. The Additions part is to calculate the size of motor once you start adding stuff thats why a battery is first :)


Its certainly not definitive and its certainly not a bible but it should help the first timers or modders looking for a new toy. Just because the maths comes out fine it doesn't mean the plane will. As we have seen some planes are good EasyStar clones with similar specs but space inside them is 40% less thanks to giant walls. Research is your friend I just hope this does a little research for you. Values for the additions are in row 3 so make it bigger and change them if you want (APM is just the basic APM setup - APM + oilpan + MTK).


Feel free to post specs for planes that you want or like.

Data required: Name, Wingspan, Wing Area, Flying Mass

Name: Northrup GlobalHawk

Wingspan: 66ft

Wing Area: 169sqft


RC Plane Data

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  • Quality post Ritchie.  That's where we want to peg the contributions.
  • I stumbled upon a thread in RCG about calculating motor parts. It wasn't as precise as I had hoped so the motor choice stuff I've left out but I've added stall speed to the sheet now. Not sure how much help actually is yet.
  • I'd be more than happy to Chris direct manufacturer numbers means it will be perfect and not just a reseller weighing the box :) email sent ty.
  • If you are interested I can provide all info you need for our aircraft. Some are high end sUAS and a couple are foam hobby type sUAS. Send me an e-mail and I will gather all the info you need.
  • That will not happen on the spreadsheet because its about viability mathematically not physically. That why it's a research aid not definitive guide. If you want build suggestions lots of build logs are on here including mine :) my philosophy is if the maths works you just gotta keep trying. Heaviest things are batteries and motors so they go either end and other stuff in the middle. That way you can balance it more easily.
  • this would be great when there is one or two pictures showing the electronics:

    - how is it installed

    - how does it look like


    just collecting ideas how to install



  • @T.D. Gonzales

    If you want to give the app a bash all the data is in the spreadsheet (airframe data and calculations). There is nothing to hard in it and should give you a nice start. Perhaps I should get the site back up and have a database for this stuff.

  • @Ritchie 

    Well either way gathering the data is really helpful I kind of ended up guessing how big a battery to buy when I ordered my SkyFun(still in customs). This data shows that I managed to guess pretty close to right. If you want to do a program I would love to help. Since I'm just getting into this it would be a great way for me to put some skull sweat in without a lot of experience. 

  • This is helpful. Thanks!

  • @Shaw

    Well I've been very OCD about the numbers and used several sites to get the information checked and the worry is "outsiders" will see it as a joke to play while the rest of the genuine folks will find it helpful. Its a stupid concern really but I can currently back up all the figures using several vendors which means users can have faith in the information.

    Incidentally a calculator was on my site but having switched ISP the site has come down (free space :D). It wasn't a database thing just a cruncher ( driven). Might get that up again this month but given the highest hits were for my counterstrike stuff I'm not too worried.

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