Today's Message Index:
----------------------
1. 12:19 AM - Re: 701's in the Houston area? (txpilot)
2. 12:27 AM - Re: Jury Struts (txpilot)
3. 11:42 AM - Re: Zenith CH750 Detail Pictures (Brady)
4. 11:48 AM - Re: Zenith CH750 Detail Pictures (Chris Kehoe)
5. 12:15 PM - Re: Zenith CH750 Detail Pictures (Brady)
6. 03:19 PM - Re: Zenith CH750 Detail Pictures (gburdett)
7. 04:32 PM - Re: Engine comparision chart (carl)
Message 1
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| Subject: | Re: 701's in the Houston area? |
Jimmy,
I'm currently building a 701 in Conroe (CXO). There's also a guy here flying an
801.
I'm not flying (although I hope to be soon). You're welcome to take a look at
my project if you'd like. Send me a message.
Dan Ginty
N787DG
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 8345#208345
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Thanks, but I already got them together. The filing wasn't as bad as I thought.
I just added Superfil on the ends to pretty it up.
I saw an 801 on the field and the guy had his own welded steel tube assembly for
jury struts. It was much neater than what ZAC has in mind, but I imagine it
comes with a weight penalty. I was curious if anyone else out there designed
a better wheel.
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 8346#208346
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| Subject: | Re: Zenith CH750 Detail Pictures |
Stefan,
I don't mean to down talk the Jabiru 3300.
But the advertised weight is dry weigh.
I have to say that I think the Jabiru has room for improvement.
I think for the money you can get a much better engine.
You can buy a completely built Corvair with all the bells & whistles for substantially
less than the Jabiru.
Granted I am very Biased towards the Corvairs.
I build Corvair Conversions and My next engine is being designed to compete Directly
with the 3300.
So far I feel comfortable saying that I think my next engine will be lighter than
the Jabiru installed with comparable or better power.
That being said; I want to point out another advantage to the Corvair over the
Jabiru & Rotax. And that is parts availability and cost.
I think most people look at the initial cost, power, and weight too closely and
forget to think down stream a bit.
Can you buy Jabiru and Rotax parts at your local auto parts store?
What is the difference in cost for any given part compared to a Corvair?
I urge you to keep a close eye on the Corvair movement and learn as much as possible
about the builders as you can.
William Wynne's web site is full of information: www.flycorvair.com
Mark Langford's site is equally informative: http://home.hiwaay.net/~langford/
Food for thought,
--------
Brady McCormick
Poulsbo, WA
www.magnificentmachine.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 8392#208392
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| Subject: | Re: Zenith CH750 Detail Pictures |
Sounds like you and I have the same gameplan. Amphibs are in my long
range plans, but initially I want to fly with the Tundra tires for
awhile. As far as engines go, the Corvair is beyond a doubt the most
bang for the buck, but it's a bit heavy and may not provide the prop
torque we're looking for. The Jab 3300 vs Rotax 912S info below shows
the two to be close with properly trimmed props, but then there are
several other factors to consider as well. Personally, I'd prefer a six
banger purring along at 2750 RPMs over a 4 at 5500 any day.
Rotax versus Jabiru - Anticipated Ground Static Thrust for a Certain
Propeller
A propeller will produce a certain thrust based on the torque and RPM it
experiences. Consequently, an engine comparison can be done from this.
Engine Type
Model
Power (HP)
Engine RPM
Calculated Engine Torque
Actual Torque (Ft Lb)
Reduct. Gear *
Prop RPM
Prop Torque (Ft Lb)
Fuel rate (L/Hr)
Comments
Rotax
582(48)
63
6500
50.9
50.1
2.58
2519
129
27.3
Max 6800 RPM, with lower torque.
Rotax
582(48)
65
6250
54.6
54.0
2.58
2422
139
27.0
Rotax
582(48)
63
6000
55.1
55.3
2.58
2326
143
26.0
Max torque.
Rotax
582(40)
53.6
5500
50.1
50.0
2.58
2132
129
22.0
Max torque. Max 6400 RPM, with a lower torque.
Jabiru
2200
84
3300
133.7
134.0
1
3300
134
18.0
Jab with Mod combust chambers.
Jabiru
2200
75
2900
135.8
136.0
1
2900
136
16.0
Max torque = 137 Lbf Ft @ 2700 RPM
Jabiru
2200
62
2400
135.7
135.0
1
2400
136
14.0
14 L/hr @ cruise (75%)
Rotax
912
81
5800
73.3
72.3
2.273
2552
164
22.8
Max 5 min @ this RPM.
Rotax
912
78
5500
74.5
74.0
2.273
2420
168
22.0
Max cont. pwr RPM.
Rotax
912
75
5200
75.8
75.6
2.273
2288
172
21.5
Rotax
912
73.5
5000
77.2
77.5
2.273
2200
176
21.2
Max torque.
Rotax
912
68.5
4800
75.0
75.0
2.273
2112
170
20.6
Rotax
912
62
4350
74.9
74.0
2.273
1914
168
19.2
Jabiru
3300
126
3300
200.5
199.0
1
3300
199
28.5
With Mod combustion chambers.
Jabiru
3300
120
3100
203.3
203.0
1
3100
203
27.1
Jabiru
3300
113
2900
204.6
205.0
1
2900
205
25.6
Jabiru
3300
109
2750
208.2
208.0
1
2750
208
24.7
Max torque.
Jabiru
3300
100
2550
206.0
206.0
1
2550
206
22.6
Jabiru
3300
93.5
2387
205.7
205.0
1
2387
205
21.1
Advertised fuel rate = 20 L/hr at cruise.
Jabiru
3300
88
2263
204.2
204.0
1
2263
204
19.9
Jabiru
3300
84
2145
205.7
203.0
1
2145
203
19.0
Jabiru
3300
80
2058
204.2
203.0
1
2058
203
18.1
Rotax
912S
100
5800
90.6
89.2
2.43
2387
217
27.0
Max 5 min for take-off.
Rotax
912S
95
5500
90.7
91.5
2.43
2263
222
26.0
Max cont. pwr.
Rotax
912S
90
5000
94.5
94.4
2.43
2058
229
20.0
Rotax
912S
86
4800
94.1
94.6
2.43
1975
230
18.0
Max torque.
* Assume minimal loss from engine torque to prop torque in reduction
gear.
Conclusion: For a similar prop, anticipate Jabiru 3300 to have greater
static thrust than Rotax 912 and slightly lower than 912S with a prop
trimmed for 5800 engine RPM. Prop experiencing 2387 RPM & 217 Lbf Ft
torque. Note that the Jabiru 3300 would have 205 Lbf Ft of torque at
that 2387 prop RPM. Should trim prop for Jab optimum 2750 RPM and torque
of 209 Lbf Ft. Mario Gaulin, Ontario, Canada. 29 Oct 2003.
Message 5
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| Subject: | Re: Zenith CH750 Detail Pictures |
Chris,
Rather than re type all the info, have a look at Marks site.
This link is his camshaft page and as you can see the Corvair will easily produce
197 Foot pounds of torque.
Keep in mind that this is only a 3.1 liter Corvair
I have a slightly larger Corvair in the works and a hydraulic roller cam may be
utilized.
Marks link is: http://home.hiwaay.net/~langford/corvair/cam_advance.html
If you would like to discuss any specifics please feel free to Email me off list.
brady@magnificentmachine.com
--------
Brady McCormick
Poulsbo, WA
www.magnificentmachine.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 8399#208399
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| Subject: | Re: Zenith CH750 Detail Pictures |
It will be interesting to see how the RotaMax progresses over the next few years-
good torque, good weight, and power in the right range by the limited info
available but it is in the very early aviation use stage-and it needs a PSRU.
A real experiment right now. If it proved to be reliable-it would be a good CH
750 match . Zenith indicates that a 72-maybe a 74 would be the largest prop that
would fit well. I believe it is a 72 on it right now although not pitched
to perform-just for joy rides.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 8423#208423
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| Subject: | Re: Engine comparision chart |
Chris.
I have to comment on the fuel flow numbers given for the Rotax 912 in
your post. My 701/912 amphib with a WD three blade 70"regularly gives
me:
Prop Pitch (At Tip) RPM Fuel Flow
8.5' 5000 15-16 LPH
9.5' 4800 13-14 LPH
This is measured consumption on several Xcountry flights two of them
from the Ottawa Canada area to Oshkosh. I have ordered a GSC in flight
adjustable with WD blades and hope to improve on fuel flow and overall
performance. Anyone with experience with this prop please comment. Right
now I am looking for 8 mm X 1.25 mm pitch metric bolts to mount the prop
to the 912 hub. I don't have exact dia yet but shank is not more than 12
mm and thread 25 mm. Anyone with a source please advise.
We are getting beautiful 20'C weather in the land of the freeze and it's
Thanksgiving Day tomorrow,
Regards
Carl
----- Original Message -----
From: Chris Kehoe
To: zenith701801-list@matronics.com
Sent: Sunday, October 12, 2008 2:47 PM
Subject: Re: Zenith701801-List: Zenith CH750 Detail Pictures
Sounds like you and I have the same gameplan. Amphibs are in my long
range plans, but initially I want to fly with the Tundra tires for
awhile. As far as engines go, the Corvair is beyond a doubt the most
bang for the buck, but it's a bit heavy and may not provide the prop
torque we're looking for. The Jab 3300 vs Rotax 912S info below shows
the two to be close with properly trimmed props, but then there are
several other factors to consider as well. Personally, I'd prefer a six
banger purring along at 2750 RPMs over a 4 at 5500 any day.
Rotax versus Jabiru - Anticipated Ground Static Thrust for a Certain
Propeller
A propeller will produce a certain thrust based on the torque and RPM
it experiences. Consequently, an engine comparison can be done from
this.
Engine Type
Model
Power (HP)
Engine RPM
Calculated Engine Torque
Actual Torque (Ft Lb)
Reduct. Gear *
Prop RPM
Prop Torque (Ft Lb)
Fuel rate (L/Hr)
Comments
Rotax
582(48)
63
6500
50.9
50.1
2.58
2519
129
27.3
Max 6800 RPM, with lower torque.
Rotax
582(48)
65
6250
54.6
54.0
2.58
2422
139
27.0
Rotax
582(48)
63
6000
55.1
55.3
2.58
2326
143
26.0
Max torque.
Rotax
582(40)
53.6
5500
50.1
50.0
2.58
2132
129
22.0
Max torque. Max 6400 RPM, with a lower torque.
Jabiru
2200
84
3300
133.7
134.0
1
3300
134
18.0
Jab with Mod combust chambers.
Jabiru
2200
75
2900
135.8
136.0
1
2900
136
16.0
Max torque = 137 Lbf Ft @ 2700 RPM
Jabiru
2200
62
2400
135.7
135.0
1
2400
136
14.0
14 L/hr @ cruise (75%)
Rotax
912
81
5800
73.3
72.3
2.273
2552
164
22.8
Max 5 min @ this RPM.
Rotax
912
78
5500
74.5
74.0
2.273
2420
168
22.0
Max cont. pwr RPM.
Rotax
912
75
5200
75.8
75.6
2.273
2288
172
21.5
Rotax
912
73.5
5000
77.2
77.5
2.273
2200
176
21.2
Max torque.
Rotax
912
68.5
4800
75.0
75.0
2.273
2112
170
20.6
Rotax
912
62
4350
74.9
74.0
2.273
1914
168
19.2
Jabiru
3300
126
3300
200.5
199.0
1
3300
199
28.5
With Mod combustion chambers.
Jabiru
3300
120
3100
203.3
203.0
1
3100
203
27.1
Jabiru
3300
113
2900
204.6
205.0
1
2900
205
25.6
Jabiru
3300
109
2750
208.2
208.0
1
2750
208
24.7
Max torque.
Jabiru
3300
100
2550
206.0
206.0
1
2550
206
22.6
Jabiru
3300
93.5
2387
205.7
205.0
1
2387
205
21.1
Advertised fuel rate = 20 L/hr at cruise.
Jabiru
3300
88
2263
204.2
204.0
1
2263
204
19.9
Jabiru
3300
84
2145
205.7
203.0
1
2145
203
19.0
Jabiru
3300
80
2058
204.2
203.0
1
2058
203
18.1
Rotax
912S
100
5800
90.6
89.2
2.43
2387
217
27.0
Max 5 min for take-off.
Rotax
912S
95
5500
90.7
91.5
2.43
2263
222
26.0
Max cont. pwr.
Rotax
912S
90
5000
94.5
94.4
2.43
2058
229
20.0
Rotax
912S
86
4800
94.1
94.6
2.43
1975
230
18.0
Max torque.
* Assume minimal loss from engine torque to prop torque in reduction
gear.
Conclusion: For a similar prop, anticipate Jabiru 3300 to have greater
static thrust than Rotax 912 and slightly lower than 912S with a prop
trimmed for 5800 engine RPM. Prop experiencing 2387 RPM & 217 Lbf Ft
torque. Note that the Jabiru 3300 would have 205 Lbf Ft of torque at
that 2387 prop RPM. Should trim prop for Jab optimum 2750 RPM and torque
of 209 Lbf Ft. Mario Gaulin, Ontario, Canada. 29 Oct 2003.
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