Why fixed wing is better for mapping than rotary wing

with 3 Comments

Until the last few weeks, I had been assuming that we would be looking at using a quadrocopter for this research. I knew this was going to involve a lot more engineering than a balloon or kite, but until looking into it a few weeks ago, I didn’t know how much more.

Essentially, all the parts must be extremely well balanced, and thus tolerances for various parts are very, very low. This drives up manufacturing costs and makes fabricating our own parts with a 3d printer/whatever extremely time consuming and in the end, not really viable. This is compounded by increased software complexity, which I know we are all OK with conceptually, but in practice is not realistic or sustainable. Once we are in Iceland, we don’t want to need to minimize maintenance and not have the most fragile setup possible.

The only benefit of a rotary wing UAV is the ability to generate lift without horizontal thrust, which is not what we require. We are doing one long continuous flight, criss-crossing a terrain. This problem is best suited to fixed-wing UAVs, which are simpler to maintain and fly, can carry greater payloads and are not as sensitive, are much, much more efficient at generating lift, and if we run out of batteries, can glide down to earth. The biggest downside to fixed wing designs is the need for horizontal thrust to generate significant lift, making horizontal takeoff/landing necessary. This is not a problem in Iceland, where we have plenty of space. This is all leading to the final point, which is that this limited lift which can be generated by a rotary wing UAV means a payload would keep our flight times below 20 minutes, making mapping outside of a small radius around us difficult. I think we could easily get up to an hour or more on a fixed wing design with a payload with the same (if not smaller) budget.

So, in summary, even though it’s way less sexy, the fixed wing aircraft is our only real option. My next course of action is contacting old friends who are either hobbyist UAV flyers or in aerospace.

3 Responses

  1. Nic Arnold

    I believe we had already gone over some of theses. There is no perfect drone (yet) for all of our purposes. The biggest issue with fixed wing is generally cost, its about $1400 for a drone capable of mapping compared to $650 for a basic quadcopter capable of small area mapping. I’m not convinced that we will be able to 3D print a drone capable of what we need it for. While some are great for hobby builds, the current 3D printed drones that are up to par with prebuilt drones cost no less to make and generally not as well made. Before moving forward at all on which to buy we need to get a concrete idea on what we need the drone to actually do.

  2. Benjamin Liebersohn

    Good points. I agree a custom fabricated models are almost as unlikely as 3d printing, but nonetheless with exploring. What quad/fixed drones were you looking at with those price points?

  3. Nic Arnold

    Definitely keep exploring possibilities, but the big advantage of a rotary drone is relatively stable images on a constant location, so if you are looking at one particular area you could use a live view and watch from a computer. I don’t know about live view from a fixed wing, its probably possible, but you would have to do several flybys to get a good look at anything and most mapping work (better quality and larger area set than quadcopter) would have to be done in post processing. The base model of DJI’s phantom can be gotten at 650USD-800USD depending on the deals and discounts available (http://store.dji.com/product/phantom-3-standard?from=buy_now&site=branchsite).

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