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dougsnash
Joined: 14 Apr 2008
Posts: 281
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 Posted: Sun May 15, 2011 4:24 am Post subject: 701 Streamlined Strut Covers |
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I finished installing the streamlined strut covers on my CH-701 yesterday. Many 701 builders suggested this was good for between five and eight MPH increase in cruise. Honestly, I'm not sure I got even one MPH cruise increase.
Where I did get a significant improvement was in the slow speed end of the cruve. Before the plane would start to get a bit mushy with a climbout speed of about 40 MPH indicated. Not ready to stall, just not as solid as say 55 MPH. Now I can pull the nose up to 30 MPH and the plane feels rock solid.
I did some stalls with this new configuration and was amazed to be falling vertically with almost no forward movement. This was an illusion caused by a stiff headwind but was still "Totally Cool." The stall comes on with minor buffet at about 20 MPH indicated with no flaps. Essentially below the white arc on my airspeed indicator.
Another advantage to the strut covers is they look fantastic. I wasn't sure how they were going to turn out but am thoroughly impressed. I think I'm going to take some pictures today.
So the question is, am I missing something that caused the limited increase in cruise performance? I have the 80hp Rotax with a three blade Warp Drive prop. The blades are 70 in diameter, have nickle leading edges and are set to about 8 deg. I'm cruising about 5200 RPM at an indicated 78 MPH. Full power climbout gives me about 5400 RPM and wide open straight and level gives me about 5800 RPM. I didn't try a speed run last night at full power because of the stiff wind.
Any suggestions other than removing my slats? They are staying where they are.
Doug MacDonald
CH-701 from scratch
NW Ontario, Canada
Do not archive
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stolpilot.wilde(at)gmail.
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| Posted: Sun May 15, 2011 10:30 am Post subject: 701 Streamlined Strut Covers |
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On 5/15/2011 5:22 AM, MacDonald Doug wrote:
| Quote: |
I finished installing the streamlined strut covers on my CH-701 yesterday. Many 701 builders suggested this was good for between five and eight MPH increase in cruise. Honestly, I'm not sure I got even one MPH cruise increase.
Where I did get a significant improvement was in the slow speed end of the cruve. Before the plane would start to get a bit mushy with a climbout speed of about 40 MPH indicated. Not ready to stall, just not as solid as say 55 MPH. Now I can pull the nose up to 30 MPH and the plane feels rock solid.
I did some stalls with this new configuration and was amazed to be falling vertically with almost no forward movement. This was an illusion caused by a stiff headwind but was still "Totally Cool." The stall comes on with minor buffet at about 20 MPH indicated with no flaps. Essentially below the white arc on my airspeed indicator.
Another advantage to the strut covers is they look fantastic. I wasn't sure how they were going to turn out but am thoroughly impressed. I think I'm going to take some pictures today.
So the question is, am I missing something that caused the limited increase in cruise performance? I have the 80hp Rotax with a three blade Warp Drive prop. The blades are 70 in diameter, have nickle leading edges and are set to about 8 deg. I'm cruising about 5200 RPM at an indicated 78 MPH. Full power climbout gives me about 5400 RPM and wide open straight and level gives me about 5800 RPM. I didn't try a speed run last night at full power because of the stiff wind.
Any suggestions other than removing my slats? They are staying where they are.
Doug MacDonald
CH-701 from scratch
NW Ontario, Canada
Do not archive
Doug: After some time on mine, I believe I got about 4 more mph for the
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same throttle setting. I can cruise at 85 mph at 5200 rpm with no
problem with a 912S and the prop is set at 11.5 degrees. I don't know
if it is just me but it seems to float more on landing with the strut
covers on. This is a 701 so we are talking about only another 20 feet
before touchdown. Or it could be just bad technique on my part.
Dan Wilde
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Tommy Walker
Joined: 12 Jan 2006
Posts: 442
Location: Anniston, AL 36207
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| Posted: Sun May 15, 2011 12:08 pm Post subject: 701 Streamlined Strut Covers |
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Doug,
We had about a 11.5 degree setting with our warp/rotax setup. I believe we
set it to get about 5200 rpm on the ground. I'm surprised you have such a
shallow prop pitch. Our's was a 912S though, so maybe that was the
difference.
Sorry about introducing a new subject into this thread.
Tommy Walker in Alabama
| Quote: |
--> Doug<dougsnash(at)yahoo.com>
So the question is, am I missing something that caused the limited
increase in cruise performance? I have the 80hp Rotax with a three blade
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Warp Drive prop. The blades are 70 in diameter, have nickle leading edges
and are set to about 8 deg. I'm cruising about 5200 RPM at an indicated 78
MPH. Full power climbout gives me about 5400 RPM and wide open straight and
level gives me about 5800 RPM. I didn't try a speed run last night at full
power because of the stiff wind.
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_________________
Tommy Walker
N25A - Anniston, AL |
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dashwood
Joined: 24 Jan 2009
Posts: 73
Location: sw ontario canada
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| Posted: Sun May 15, 2011 1:37 pm Post subject: Re: 701 Streamlined Strut Covers |
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i am running a t6041 warp on a 912 set to 12deg. this is in the record book for the plane but i seem to recall the builder sampling up to 14deg. and settling back to 12 or slightly above.i don't think i have ever run a full power tied down run up. too scary for me I'm sure the builder did . his rendition of when the rope broke is a hoot. i do get takeoff rpm of 5200 to 5250rpm at 60indicated. a 50mph indicated climb may be a little less at around 5180. level flight (full throttle) will always start at 5280 and will gradually creep to 5400. slight nose down will bring on the 5500rpm over rev warning light and sounder. i always have to decrease throttle in decline. i consistently cruse at 85 to 90mph indicated. i am disappointed if the gps doesn't read a solid 90mph ground speed. one thing i have learned in my short flying experience is the air speed indicator vary greatly from one plane to the next. a formation flight of several planes will get you as many airspeed reports as there are planes.
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_________________
Ross Alexander: CH701 driver 912ul 788tt
It only takes two things to fly, airspeed and money
Last edited by dashwood on Sun May 15, 2011 8:40 pm; edited 1 time in total |
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dougsnash
Joined: 14 Apr 2008
Posts: 281
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| Posted: Sun May 15, 2011 6:56 pm Post subject: 701 Streamlined Strut Covers |
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Tommy, I think I have two things working against my prop pitch. First is the 80 hp instead of 100 hp. Second is the 70 inch prop as opposed to the 68 that most people run. I chose the longer prop because I plan on going with floats someday. I'm kind of regretting that descision now.
I'm going to try and put a little more pitch back in. I've tried a few different settings from up near 11 back down to the 8 I have now. Maybe 8.5 or 9 might work better with the less airframe drag I have now.
Thanks to everyone for the feedback.
Doug MacDonald
CH-701 scratch
NW Ontario, Canada
Do Not Archive
--- On Sun, 5/15/11, Tommy Walker <twalker(at)cableone.net> wrote:
| Quote: | posted by: "Tommy Walker" <twalker(at)cableone.net>
Doug,
We had about a 11.5 degree setting with our warp/rotax
setup. I believe we
set it to get about 5200 rpm on the ground. I'm
surprised you have such a
shallow prop pitch. Our's was a 912S though, so maybe
that was the
difference.
Sorry about introducing a new subject into this thread.
Tommy Walker in Alabama
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ruruny(at)aol.com
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| Posted: Mon May 16, 2011 3:05 am Post subject: 701 Streamlined Strut Covers |
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...I have the 80hp Rotax with a three blade Warp Drive prop.
The blades are 70 in diameter, have nickle leading edges and are set to about
8 deg. I'm cruising about 5200 RPM at an indicated 78 MPH. Full power climbout
gives me about 5400 RPM and wide open straight and level gives me about 5800
RPM.
Doug,
I have an 80 hp rotax 912, 68" warp drive prop 3 blade with no nickel leading edges.
Originally the prop was 70" as I was planning on the 912s. When I got the 912 I called
warp drive and they recommended the prop 68". I sent it back and they cut the blades down
for $10 each.
I originally set my prop pitch for 11.5 deg as this seemed the consensus for what most people
were running but I could only get 4800rpm at full throttle climb. She climbed ok but the cruise was
awesome in the 90s. According to many on the rotax-list I was lugging engine. The next flights I
decreased the pitch by 1 deg gaining 200 rpm on each adjustment but loosing cruise performance.
I ended up with 8.5 deg with 5700 climb and about 75mph cruise at 5200 rpm
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rockiedog2
Joined: 03 Mar 2010
Posts: 19
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| Posted: Tue May 17, 2011 6:09 am Post subject: Re: 701 Streamlined Strut Covers |
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>>> one thing i have learned in my short flying experience is the air speed indicator vary greatly from one plane to the next.
You got that right! Our IAS can vary so much as to be useless for comparison purposes, the only real way to know what we have is careful, thoughtful testing using the GPS. An 80 mph IAS plane could easily be doing 85 or 75, or even more difference than that. But I know everybody already knows that, right? It just appeared that thruout this thread everybody was mostly referencing IAS for their comparison as well as evidence of what their particular plane was doing.
My 701 airspeed is accurate from about 75 down to 36 mph. Below 36 the error grows as speed decreases, above 75 the error grows as speed increases. At 30 mph TAS stall it's indicating 20 mph. At 94 TAS cruise it's indicating 110 mph.
FWIW
Joe
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