Mercury Mallard
08-09-2007, 06:17 PM
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Mercury Mallard
I took a notion to build an early competition power model and chose the Mercury Mallard as I had built quite a few Mercury models some time ago and was always impressed with the designs and quality of the kits.
The Mallard was designed in 1950 ( I think) as a 48" competetition power model - ie a power burst of 10 seconds and hopefully a 3 (?) minute glide.
Phil Smith sells the Mercury plans and I had the Mallard scaled up for R/C to 72" span and to power it with a 400 watt brushless (which took it up almost vertically).
I kept the CG as per plan at 83% back from leading edge which was fine as long as it was a calm day and I took power off gently to let it level off and go into a turn. The gentlest of control to nudge it to keep it in the field worked, but any attempt to straighten the glide for any length of time ( or in wind to keep it upwind ) simply put it into progressive stalling which could only be cured by putting it back into circling. ie the model was behaving as a competition model and was not designed for in flight control with the aft CG. lesson learned for me - for R/C keep CG in usual 30% or thereabouts.
Thermals took it up with ease- getting them down meant lots of down to fly straight out of thermal and not my usual practise of full up and full rudder to tight circle down but stay in vicinity of thermal to hitch a ride back up once I was comfortable with height compatable with my eyesight and below the local light aircraft flybies.
I have posted a few photos in my gallery - the landing sequence was almost a free flight landing with little pilot interference - them were the days
John
The Mallard was designed in 1950 ( I think) as a 48" competetition power model - ie a power burst of 10 seconds and hopefully a 3 (?) minute glide.
Phil Smith sells the Mercury plans and I had the Mallard scaled up for R/C to 72" span and to power it with a 400 watt brushless (which took it up almost vertically).
I kept the CG as per plan at 83% back from leading edge which was fine as long as it was a calm day and I took power off gently to let it level off and go into a turn. The gentlest of control to nudge it to keep it in the field worked, but any attempt to straighten the glide for any length of time ( or in wind to keep it upwind ) simply put it into progressive stalling which could only be cured by putting it back into circling. ie the model was behaving as a competition model and was not designed for in flight control with the aft CG. lesson learned for me - for R/C keep CG in usual 30% or thereabouts.
Thermals took it up with ease- getting them down meant lots of down to fly straight out of thermal and not my usual practise of full up and full rudder to tight circle down but stay in vicinity of thermal to hitch a ride back up once I was comfortable with height compatable with my eyesight and below the local light aircraft flybies.
I have posted a few photos in my gallery - the landing sequence was almost a free flight landing with little pilot interference - them were the days
John
