Wing tip wheels, one or several?

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Our self-launch glider has downturned wing tips. From the factory, there was nothing more than a skid to make contact with the ground. Over time, people seem to have settled on putting a roller-blade wheel there, presumably because it dramatically improves ground handling. However, the wheel isn't very pretty and because of the drooped tips there's no way to install the wheel without it dramatically disturbing airflow.

I'm wondering if two small inline wheels could suffice to replace the one big one. In my mind, the advantage of a bigger wheel is reduced rolling resistance on uneven ground. However, inline wheels might close that efficiency gap, without having as large an effect on airflow.

Thoughts?

[PGS]

On Friday, June 5, 2020 at 2:54:31 PM UTC-4, wrote:
> Our self-launch glider has downturned wing tips. From the factory, there was nothing more than a skid to make contact with the ground. Over time, people seem to have settled on putting a roller-blade wheel there, presumably because it dramatically improves ground handling. However, the wheel isn't very pretty and because of the drooped tips there's no way to install the wheel without it dramatically disturbing airflow.
>
> I'm wondering if two small inline wheels could suffice to replace the one big one. In my mind, the advantage of a bigger wheel is reduced rolling resistance on uneven ground. However, inline wheels might close that efficiency gap, without having as large an effect on airflow.
>
> Thoughts?

A roller blade wheel is not that large, I'm surprised that it would "dramatically" disrupt airflow. Perhaps you are correct in theory, but many times theory is not proportional to practical reality.

[Kenz Dale]

>> A roller blade wheel is not that large, I'm surprised that it would "dramatically" disrupt airflow. Perhaps you are correct in theory, but many times theory is not proportional to practical reality.

That's fair. Let me specify that it dramatically disturbs local airflow. I doubt it really affects things 2m away.

In our case, they're really chunky wheels and they're actually mounted outboard of the wingtips. So they have an outsized effect vs. more standard approaches. This is what motivates the desire to change. I'm just guessing here, but I wonder if they don't have as large an impact as not properly taping seals.