The links below are from Google and are not necessarily endorsed by Art Wallace
Force One Designed by Laddie Mikulasko
Review by Art Wallace
Flight
The
plane was in perfect shape. Every thing was programmed. I had about 50%
exponential on all control surfaces. I took it out to the field. fueled
it up. Started the engine. Everything was perfect, idle perfect, top end
perfect. Idle up was working. I taxied out to the runway and lined it
up. The wind was about 10 knots right down the middle of the runway. I
accelerated to full throttle, started to rotate, and it died. I picked
it up and tried to restart it. No fuel?
I opened up the fusalage and it is full of fuel. The tank had two
cracks in the rear corners where I had slipped it over the main spar.
Ugh! Everything is soaked in fuel.
So
I get a new tank. Replace the foam. Check the CG. I check for leaks. I
dry out the system. I take it
out to the field. Range check it. I start it up. Everything is working.
I taxi down the runway at full blast. Now this is not so easy to do because
the plane had a tendency to tip over on it wing tips as you accelerate.
This is embarrassing but wing tip skids keep the damage down. I rotate
and the plane flies like a duck with a rock taped on it’s back. It just
wants to stall. It has the flight characteristics of a ducted fan plane
that is going to crash because it has too high a wing loading and not
enough power. The plane noses in after stalling four times.
I
bring it back to the pits. I fuel it up. There is miraculously no damage.
I start the engine. This time I adjust it with the tachometer to get maximum
speed with smoke (O.S. 0.46 FX with a 10-6 APC pusher). I run up the throttle,
let it go. We have a paved runway that is about 400 feet long. I rotate
just at the end and I am in the air. It flies better. Not too fast. Very
heavy. It won’t maintain a vertical climb. It is very twitchy. I zoom
around. It falls out of the sky on Cuban eights. It is hard to fly well.
Finally, I am about 50 feet up and 200 feet from the runway. The engine
dies. The plane just drops like a rock. The glide is just down. It survives
without damage. I put in 90% exponential
on all surfaces. I then fly it well for two flights. I make sure they
are about 8 minutes so I don’t get to the point where it can’t feed fuel
from the mid tank feed that Laddie
Mikulasko recommends. I never bothered to fix the tank problem. I think
it is fundamentally bad design to have the fuel slosh to the back of the
tank, and the clunk not be able to get to it.
Sucking air is a bad idea in a plane that falls out of the sky
if the engine dies. Despite these
problems, I manage to fly it well and put it on the runway both times.
I
take it home. Tune it up a bit more. Get everything to work better. I
flew it again. This time the engine was working better. It was almost
fast. It almost had enough power. I looked on Tower Hobbies to get a pusher
prop with more pitch. You can’t put any prop larger than a 10 on it because
the prop is in a groove. There just aren’t any other pusher props other
than the APC 10-6 that I had. It still has a thrust to weight less than
1. It also doesn’t have wind over the control surfaces at slow speeds.
I have never flown a ducted fan but that is supposed to be one of the
differences between the ducted fan planes and prop jets. It was definitely
harder to control at low speeds.
I
took it out today. I flew a warm up flight with the Delta Vortex. Multiple
Cuban eights, vertical eights, hammer heads, split S’s, hovering, hammer
heads with a roll on the way up and down, inverted flight, multiple square
loops. Perfect landing in high wind. I feel good.
I
fuel up the Force One. I tune the engine to peak thrust. I blast down
the runway and rotate up. It is moving much better. The speed is higher.
I think. Wow, I have finally gotten it adjusted to fly well. I start doing
Cuban eights. I am inverted about 200 feet up and pulled up to complete
the loop. I am heading toward the ground at full throttle. It
is a maneuver that I have made many hundreds of times with the Delta Vortex.
The Force One made it to an attitude where the wings were level, the engine
was a full throttle, the unfortunate thing it that the wing is in a high
speed stall and it is plummeting toward the ground at 100 miles an hour.
It was very, very strange. The plane just fell out of the sky like a lead
pancake. Engine running at full blast. It was as if the wing just stopped
working. No lift. Nothing. I must have stalled the entire wing with the
up elevator command. The plane landed absolutely flat. The landing gear
were driven through the wing. There was no damage to the nose because
the plane was absolutely flat when it hit. The wing has many, many broken
spars, ribs, the radio trays were broken, the epoxy coated balsa in the
fuel compartment was shattered. It is a total loss.
What
went wrong? My Force One weighed
in at 5 lbs. It had seven servos and a 1300 ma battery pack. The wing
loading was a bit high (18.6 oz/square foot) but not terrible. I think
what went wrong was that I had too much elevator throw. With elevons and
the elevator linked together, I was able to stall the entire wing simultaneously.
When I pulled up from inverted, despite having a forward velocity of 100
mph, the wing simply stalled. I pancaked in.
I
am not impressed with this airplane. I think it looked cool, but there
is a fundamental limitation to the design. You can’t put a larger prop
on the plane because it is in the center of the wing. You can’t increase
the pitch because there aren’t pusher props available with more pitch.
You have to be very careful with engine placement. I had to route
out my engine mount to get the engine to sit further forward to get prop
clearance. I had built it perfectly, except I forgot about the thickness
of the monocoat on the engine mount which wrecked my prop clearance. Moving
the engine forward required modifying the mount and remounting the engine.
The prop must loose some efficiency being in the wing. There is little
to no air flow over the control surfaces at low forward speeds. There
may be some strange behaviour with lift going through the engine hole
allowing a high speed stall.
My
impression is simple. If you want a really good delta wing plane build
or buy a Delta Vortex. Avoid the Force One unless you want a plane that
will give you the introductory difficulties of a ducted fan at low cost
and lower speeds.
Which
Delta Wing plane do I recommend? The
one with 200+ flights and really good aerobatics.
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The links below are from Google and are not necessarily endorsed by Art Wallace