It is interesting to compare the specs on a Dyke Delta with
a BD4. Correct me if I get the numbers wrong Kelly.

.... Gross ..empty ..HP..rate cl..top spd..span..Wing area..stall
BD4  2000 ...1080...180...1400 .....183 ...26 ft..102....... 61
Dyke 1950 ...1100...180...2000 .....190 ...22 ft..183....... not listed

The span loading which is another way of saying aspect
ratio (sort of) is nearly the same.  The BD4 is the only 2000
pound gross weight experimental airplane that I could find specs for.

The numbers are from Don Crawford's book A Practical
Guide to Airplane Performance and Design.

Most flying wings have surface area that does not provide lift.
In fact  some part of the rear part of the wing must provide down force
since the CG remains ahead of the center of lift. The loss of fuselage
drag is therefor made up to some extent by an increase in surface
area of the wing.

The numbers are pretty close. The top speed difference may be significant
or may just be  experimental error. The BD4 is a real box with fixed gear
and the Dyke Delta is fairly clean with retractable gear. Same goes for
rate of climb as the power loading of the BD4 is lower than the Dyke Delta.
It would be interesting to know what the best climb speeds were for
both airplanes. The over all efficiency is about the same.
Paul Lamar

Paul,
  It would be hard to find a Lyc. 0-360 powered Dyke
Delta with a 960lb empty wt. Most are closer to 1100
lbs and those with a constant/speed prop even heavier.
  Gross wt has been increased to 1950lbs,climb of 2000
fpm is at light wt. Top speed varies but some of the
cleaner versions have a top cruise approaching 190mph.
  I believe a 13b powered Dyke has the potential to be
both lighter and faster.

The Delta newsletter editor had
the first engine run of his 13B powered Dyke in late Dec.
  He should be flying this year if all goes well.His 13B
is from Atkins,Ross 2.85 psru,Ivo 3-blade elect,Tracy's
EFI/IGN box.He plans to fly with carb then switch to EFI
after test flights.

 Kelly Troyer

Dyke Delta/13B Rotary Power

Thanks Kelly. I thought that data might be wee bit inaccurate here and there.
I corrected the above table. The original  empty weight to gross weight
ratio was exceptional but not too far off rag and tube airplanes.
Rag and tube have always been exceptional. Particular the
external braced wing versions.

Carbon fiber airplanes have yet to achieve those ratios. My Kis 
Cruiser with carbon reinforcement here and there spar caps etc., etc. 
has a gross weight of 2400 pounds and an empty weight of 1300.
Better than the C182 however at 1900 lb/3000 lb.

It is great to hear about yet another rotary powered airplane. They just
keep coming out of the wood work.

Won't be too long before the rotary will be light airplane engine of choice.

BTW what is best climb speed for the Dyke Delta?

Paul Lamar
 
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