| >> The author wrote that he described a Heinkel 162 powered by this DF
>> unit last year. ..... does the author give any more info ?
The article would have been written in '89, but it appeared in the
March 1990 issue, page 16.
"Karl-Dieter Wiegand ... with a ducted fan Heinkel 162 Salamander
powered by a Keller 80/11 (cobalt) on thirty-six 900 mAh cells. Karl
built the plane from a Bauer kit, the ducted fan is also from Bauer,
the BM 40/81. I do not see this particular unit listed in the Bauer
advertisements. The Salamander is normally flown with a .60 engine and
a BM-50-S fan unit, which I think is equivalent. The BM-50-S uses a
10-15 cubic centimeter engine (.60 to .90 cubic inches) with a rotor
speed of 15,000-22,000 rpm. The unit can be used with five to fifteen
blades, I think Karl used twelve. The Keller motor turns the fan at
14-15,000 rpm, with a thrust of 2 kp (4.4 lbs.). Current draw is 20
Amperes, so the power input is about 720 Watts, nearly one horsepower.
Flying weight 4.3 kg (9.5 lbs.). Karl made only one major change from
the kit, he increased the span ...... to 1520 mm (60") to increase the
wing area to 50 sq. dm. (775 sq. in.). .... takeoff was ... after a
400 foot ground roll. ..... an experienced pilot to handle it safely.
..... plenty of room in it for larger cells ... a 1700 pack ...
"The Bauer Modelle line .... specialize in ducted fans, and have a
Messerschmitt ME 262 for .60 size fans ($550), the Heinkel HE 162 for
.60 engines ($322), the Skyhawk A-4 for .90 engines ($440), and the
Hornet, a sport model, for .60 engines ($220). They have three fan
units, the BM-30-7 for .40 engines ($170), the BM-50-S for .60-.90
engines ($187), and the BM-70-S for .80-.90 engines ($194). Their
catalog is $6, write to Bauer Modelle, 8501 Allersberg,
Neumarkterstrasse 28, W.Germany."
There are three photos with the article. Nice looking plane.
I hope this is what you wanted.
Alton who rarely sees a 400 foot runway for models!
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| hi folx,
nobody writing about electric ducted fans in the past, so i will update
this topic. this article has also been posted to the usenet. if anyone
is interested in one of the articles mentioned, please contact me.
there are df's available from
kress jets inc.
500 ulster landing road
saugerties, ny 12477
it is said that they also have a floppy disk available, but i do not know
what's on this disk. i suppose diagrams rpm's vs. thrust, but it might also
be their evaluation and design program.
in the september issue of Flug- und Modelltechnik (FMT), a german rc mag, is
a plan for an A10 (warthog?) designed by heino dittmar. technical data is:
span: 100 cm
length: 90 cm
weight: 1200 g
wing area: 15.5 dm^2
wing loading: 77.4 g/dm^2
power: 10 x 1000SCR, will feed both motors
engines: 2 x Speed400/6V
fan diameter: 6 cm, 3 blades
thrust per fan approx. 250 g, @9Amps. per motor
i have seen it flying, it's pretty fast (but not lightning-fast...) and
makes a very good impression. the whole fan is constructed from wood, no
ready made parts are available. construction is simple and straightforward.
built also by heino dittmar exists a mig15, a little bit smaller (maybe 80
cm span). a plan is planned for the future.
the ELEKTROFLUG SPEZIAL, a special issue of the FMT-mag dealing only with
electric matters, features a report by heino about the evolution of his fans.
also articles about the morley fan, different nicad's tested and so on.
then there is the swiss hans buehr, he has built a df based on the 540
racing motor type. the unit had 10 cm diameter prop (the new one has only
9 cm), and thrust in the 500 g range. he built a BA146, equipped with 4
df's. weight was around 5 kg, span 2.3 m, retractable gears, landing
light. a plan of these df's is available, in the elektro-Modell, another
new german mag. construction material is wood too.
on the modellbau sued, a fair held at stuttgart, a fan unit was presented
by conzelmann/natanek. it uses a speed 400, the "tunnel" is cut from foam,
with two reinforcment rings, which are also used to mount the fan.
the rotor is three-bladed, and the blades are sickle-shaped. it looked like
milled out of plastic, this might have been the prototype rotor. maybe
production will be molded (?) plastic. no further technical details up to
now, only the price: 100,- DM (complete kit, including motor) a little bit
to much in my opinion. if they would sell the rotor alone...
some observations and my personal opinion:
the magic lies in the rotor construction.
both fans i described above are constructed on a try and error basis (and
maybe still not optimal).
at the electric fly-in i attended in september, several other df's could be
seen. these where either derivates of heino dittmar's construction with 5
blades, or made out of a hairdryer. the experts (both heino dittmar and
hans buehr were present at the meeting) agreed that the hairdryer-
fan is not suitable for our purposes, the pitch of the blades would not be
enough, neither would be the pitch-distribution along the blade nor the
blade shape... they proved to be correct, as the custom made fans flew
better, faster, more realistic sound (this means, that you can hear if the
air goes through the fans "smooth" or "rough", the latter indicating some
misalignment of airspeed vs. fanspeed).
couldn't someone with the required knowledge compute an efficient rotor?
how about it, mr. selig, mr. donovan?
this part is directed to a guy from the usenet, who wrote the >... lines.
if anybody has an idea of what he is speaking, please feel free to fill in.
>I just spoke with a local guy who's into things electric. He's currently
>playing with a ferrite 540 - one of the Tamiya motors (black something?).
>He found that these things get better as they speed up, until the comutator
>gives up the ghost. Also, efficiency generally goes up with voltage.
>So, he's rewound the armature for higher voltage and is using electronic
>switching for the commutation.
could you drag him to your terminal, so he explains what he did exactly?
rewinding i can still understand, but why and how an electronic switching?
in the end it is not one of those "reversed" motors (i.e. magnets turning,
copper coils stationary and electronically commuted, this motor was
mentioned a while ago, having good efficiency but bad price), so what???
>The result is a 540 size motor running at 30+ volts, 35000 rpm, and
>putting out 500 watts! Even more amazing is that the 500W is measured at
>the OUTPUT of a reduction gearbox, so it can turn a useful prop!
^^ this means the motor is even turning higher! what a
marvel for a ducted fan!!! how about balancing at this high revs?
have fan eh, fun
joe t.
|
| Hi Joe T.,
Thanks for sending the information that came with
Hartmut's motor. The pictures of Heino's A-10, Mig-15 and
your group's Hercules were impressive. The Hercules was
painted much nicer than the picture I saw of it in Aufwind.
Electric ducted fans are still very much in the experimental
stage in this country. The Morley fan unit is being marketed
through Kress Jets and seems to perform well on certain
airplanes. I spoke with Bob Kress at the KRC meet this year
about the Electric F-15 Eagle they are marketing. I saw the
plane, but it did not fly. Tom Hunt, a Senior Aeronautical
Engineer at Grumman, who has designed several of Kress Jets
other planes(Pucara, Beech 18, P-38) expressed doubt that it
would fly. Apparently the plane has about 36 oz. of thrust
and weighs around 56 oz.
Keith Shaw's Horten IX flying wing flys well and shows that
electric ducted fans are viable. He reportedly spent 5 years
developing this model which uses two 2.6" fans of his own design
and fabrication. The fans are powered by two modified Astro 05
motors turning the fans at 32,000 RPM. Top speed is around 120 mph,
with 30 amp draw. I have seen it fly twice and it is spectacular!
I think everything has to be right for scale like ducted fan model
to fly. The weight of the batteries really does hurt here. It seems
only the most knowledgeable designers and builders are able to
do it successfully at this time.
Have you ever seen any of the commercially available offerings
from Germany fly(ie Bauer Mig)?
Regards,
Jim
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