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p.mulwitz(at)worldnet.att
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 Posted: Sat Dec 09, 2006 10:10 pm Post subject: CH701 Power: Rotax or Jabiru |
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Hi Steve,
I can't offer a factual argument that says you should use a Rotax or
Jabiru. I suppose both are quite popular, and both are likely to
provide you with a good experience.
I am building a CH601XL and plan to opt for the Jabiru 3300 rather
than the Rotax 912ULS. In this case the Jabiru offers considerably
more power than the Rotax. It also has less parts and systems to
break since it lacks the PSRU, oil cooler, and water cooling system
required on the Rotax. It also has one carburetor rather than two.
These issues are not even as clear on the 80 horsepower versions of
these products.
I don't think the propeller issue is all that important. It is
crucial that you select a proper propeller for the engine and speed
of your airplane. While there may be some efficiency differences
between a large propeller spinning slowly vs. a smaller propeller
spinning faster I believe you will get similar performance from you
plane with either choice.
In any case, I wish you good luck and many happy hours flying behind
which ever engine you choose. Both of these choices are new engines
designed (or at least offered) for use in aircraft. Either one will
probably do a lot better for you than any rebuilt automobile conversion.
Paul
XL fuselage
At 08:24 PM 12/9/2006, you wrote:
| Quote: |
Again the perennial question..redrive vs direct drive.. Is it really
a requirement to swing a large prop for 701 (non floats) at low speeds?
If so , why do some people comment that they fly behind direct
drives no problem?
What is the ACTUAL difference in performance?
I'd like to use a Jabiru 2200 because I like the engine, and I think
Rotax is really taking advantage of their niche market price wise !
(It costs more for the engine than the rest of the aircraft put
together here in Aus !!)
Factual Information GREATLY appreciated !
Steve
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jetboy
Joined: 22 Jul 2006
Posts: 233
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| Posted: Sun Dec 10, 2006 12:39 am Post subject: Re: CH701 Power: Rotax or Jabiru |
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Steve,
I went with the Jabiru 2200 the only other 701 I've been in was a 532 powered one - I will say its speeds and climb rate seem similar to mine. It was 960 lbs, I run the later 1100 lbs revision. I'm certain that an 80 hp Rotax will do better except the compromise for complexity and cost. The 912S is harsh on 701 airframes- make sure you build with the revised H Stab attach brackets. I do like the new mounts offered attaching to the rear of the engine, that may also help.
Before choosing, I ran many calculations and observations. You loose 5% or so to a small dia prop. The other problem will be weight and cooling. The 2200 gets along fine I would not like to repeat the excersise with a 3300, corvair or geared air cooled engine because of those issues. Theres a geared VW due up north soon and I'm waiting to hear if alls OK.
I would accept a new (current build) 2200 or used / new 80 hp 912 on my aircraft. I would rather run a small rotary there was nothing available.
Actual figures are cruise (at) 2900 rpm 63 KTs Max speed 70 KTs climb 1 up 400 - 800 fpm 2 up full load 200 - 400 fpm no stupid comments please a 701 is landing limited and takoff distances are much shorter as advertised. I have not had opportunity to test props etc. also my airspeed is with a static vent not factory specs which are without.
Ralph /
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Ralph - CH701 / 2200a |
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dougsnash(at)yahoo.com
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| Posted: Sun Dec 10, 2006 6:49 am Post subject: CH701 Power: Rotax or Jabiru |
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Steve, I cannot offer any real performance numbers at
this time because I am still building. I'll be
joining the front and back halves of the fuselage
sometime this week.
I've chosen the 912 UL for my plane. I stumbled
across a deal that was too good to pass up otherwise
I'd have gone for the 912ULS. Another builder in my
area is going Jabiru because of the price difference
and he likes what he has seen so far of them. Once we
have our aircraft flying, you can guarantee there will
be some head to head comparisons done.
I'm in Canada and CAN-ZAC recommended that I stay away
from the Jabiru for the 701. They said if I were
building a 601, the 3300 is an excellent engine but
for the 701 you really need the longer prop. Another
deciding factor is that I will likely end up on floats
at some point since I live in an area with so many
lakes to land in.
I guess it comes down to personal choices. As someone
else mentioned, if you do decide to go with the
Jabiru, optimizing the propeller is extremely
important.
Good luck with your building
do not archive
Doug MacDonald
Northwest Ontario, Canada
Cheap talk?
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