Well, I’ve already mentioned the speed of this delta plane:
“If powering the pictured delta by a .90 ducted fan engine and a 9*9 carbon prop turning 23000 in the air speeds of only 170 mph are possible.”
More prop pitch will reduce speed here!
The pictured one was the first “prototype” just powered by a .60 FIRE sport engine and a sport prop – a
lame dog but still much quicker than the stock Laser Arrow.
However, this delta only has the name “Laser Arrow” in common with the genuine construction:
- 6% airfoil thickness instead of much too thick stock 10 %
- fully concealed engine + pipe (glass fiber cowl construction)
- carbon spars for improving strength
- fully balsa sheeted wing for improving strength
- landing skid made of glass fiber
- Glass fiber strip incorporated into the leading edge for better strength
- fully concealed linkages
- Sandwich construction of the vertical fins: 1 mm glass fiber plus 1 mm strong balsa at each side
- Altered fin geometry
- Weight with a .90 ducted fan engine and light non-muffled tuned pipe is about 2500 grams wet
So we do realise that 170 mph are very slow for a .90 ducted fan engine powered speed plane. These 170 mph have been measured in a 200 m speed trap after a very shallow dive. You’ll hardly find a prop driven delta being faster in a 200 m trap. Please remember: While flying a 200 m FAI speed trap it is much more difficult to obtain the wanted speed than by a radar gun measurement.
I would like to recapitulate:
Even if extremely modified, prop driven deltas are not suited for satisfying speed - a quite inefficient combo. I do explicitly include the DD and Whip which I’ve flown myself.
Sounds a bit harsh, but prop driven deltas just look nice.
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