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jpspencer(at)cableone.net
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 Posted: Thu Jan 17, 2008 4:36 am Post subject: Flight Report andQuestion-701/Engine Failure |
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I got a little more interested in your post and looked a little further...looking at my Wt/Bal I find that I am usually taking off local at about 15% MAC/780#. From your post it sounds as if you were about 31%. The pitchup might well be "normal" with cg that far back and only require resetting the elevator trim to a different T/O setting.(On the big planes they calculate a trim position dependant on c/g for every takeoff-in case you didn't already know that...for all I know you may be a 747 captain or something like that). I haven't flown mine with the c/g that far back so don't know if it pitches up or not but wouldn't be surprised if it did. Somebody else with heavy weight experience should be better on that question. On the other hand, on my particular plane the trim setting doesn't seem to have much effect on takeoff...I don't notice much difference with the trim set midscale or full noseup. I wonder if you can carry any baggage at all with that weight behind the baggage compartment.
On engine failure at high pitch...Jetboy said the nose will come down no problem. I haven't flight tested that and maybe he has but I have always assumed the opposite. With the pitch angles that are immediately possible just after liftoff(very low altitude) on a max effort takeoff and climbout(912s, 579# EW), if it quits I believe it will require immediate full down elevator to save it...and if the prop isn't blowing on the elevator it isn't gonna do much cause the airspeed will be so low. In fact I have always thought that the gap between the wing roots was mostly for the prop to blow on the tail and make it work. At any rate I don't normally do extreme climbouts unless there is some high priority need for it like showing off. Has anybody gone to altitude and simulated a max effort takeoff/climbout at say 35 CAS then pulled the power to see if the nose will aggressively come down? Jetboy?Believe I will try it and see what my plane does. Will report.
Good Luck
Joe
The green one on utube
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lgold(at)quantum-associat
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| Posted: Thu Jan 17, 2008 11:02 pm Post subject: Flight Report andQuestion-701/Engine Failure |
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Thank you for the advice Joe
The weather was clear and warm here in Northern Ca. today. I flew the new 701 up to Quality Sport Plane's (QSP) hanger in Cloverdale, about 45-Miles north of my Petaluma Ca. base. Winds at 3000' over Santa Rosa's Class D airspace were as high as 30-MPH, but surface winds were light along the Russian river route into Cloverdale. Before take-off, I set the elevator trim all the way down (tab up) and did not experience any of the sharp push upwards at takeoff... Problem solved.
As to the weight and balance with the BRS behind the baggage compartment. First, I put the battery on the firewall to help with the balance. I don't know anything about MAC. (The Zenith weight/balance diagram says MAC is 1430 +/- 15mm, but I don't understand how to translate this into an allowable CG). I focusing on the Zenith 701 diagram that shows the allowed CG range is from 280 to 500mm behind the front of the slats. Is this correct? I ran the figures to see how close my planes CG comes to the back of the CG range (the 500mm point) under various conditions. Here are a few results:
Pple Fuel Bag Tot CG
wt Gal wt wt mm
__________________________
160 05 0 814 424
185 20 0 959 445
185 20 80* 1159 503 (* baggage compartment was strengthened)
370 20 40 1184 490
370 40 40 1304 500
You can see here that I can put almost 80# of baggage with a 185 pounder pilot and still be just within the CG. I can also have two 185 pound people along with 40 gal of fuel and 40 pounds of baggage without moving the CG outside of 500mm from the slats limit (provided, of course, that I am willing to degrade the planes ability handle "g" loads). From this I don't think I am out of balance. However, my plane has one characteristic that does concern me. With 20 Gal of fuel, with some difficulty I can push the back of the fuselage to the ground and it stays there! The tail will even stay on the ground with my 170#s sitting in it. Not certain what this means, but I did do my weight and balance twice because of this.
One other thing of importance. Michael Heintz at QSP examined my plane and noticed that the main gear was not tightly secured to the fuse. It actually rocked front-to-back several inches when pushed. I had followed the Zenith instructions regarding securing the gear and flat rubber strips. I remember it said not to over tighten them, but gave no torque setting. Michael changed the flat rubber from my 4-year old kit to rubber cut from an old tire. This time we torqued it down much more than I had done originally. Problem fixed... Thank you Michael.
I have to add that Michael Heintz and the people at Quality Sport Plane LLC (see http://www.qualitysportplanes.com/) have been more than helpful during the construction of my 701. They want to see that we builders do a good job. I purchased almost nothing from QSP (my kit came from a guy in Alaska who decided not to build) yet Michael was always available with free advice and help. Thank you Michael!
Les
From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Joe Spencer
Sent: Thursday, January 17, 2008 4:32 AM
To: Zenith-List(at)matronics.com
Subject: Flight Report andQuestion-701/Engine Failure
[quote]
I got a little more interested in your post and looked a little further...looking at my Wt/Bal I find that I am usually taking off local at about 15% MAC/780#. From your post it sounds as if you were about 31%. The pitchup might well be "normal" with cg that far back and only require resetting the elevator trim to a different T/O setting.(On the big planes they calculate a trim position dependant on c/g for every takeoff-in case you didn't already know that...for all I know you may be a 747 captain or something like that). I haven't flown mine with the c/g that far back so don't know if it pitches up or not but wouldn't be surprised if it did. Somebody else with heavy weight experience should be better on that question. On the other hand, on my particular plane the trim setting doesn't seem to have much effect on takeoff...I don't notice much difference with the trim set midscale or full noseup. I wonder if you can carry any baggage at all with that weight behind the baggage compartment.
On engine failure at high pitch...Jetboy said the nose will come down no problem. I haven't flight tested that and maybe he has but I have always assumed the opposite. With the pitch angles that are immediately possible just after liftoff(very low altitude) on a max effort takeoff and climbout(912s, 579# EW), if it quits I believe it will require immediate full down elevator to save it...and if the prop isn't blowing on the elevator it isn't gonna do much cause the airspeed will be so low. In fact I have always thought that the gap between the wing roots was mostly for the prop to blow on the tail and make it work. At any rate I don't normally do extreme climbouts unless there is some high priority need for it like showing off. Has anybody gone to altitude and simulated a max effort takeoff/climbout at say 35 CAS then pulled the power to see if the nose will aggressively come down? Jetboy?Believe I will try it and see what my plane does. Will report.
Good Luck
Joe
The green one on utube
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jetboy
Joined: 22 Jul 2006
Posts: 233
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| Posted: Thu Jan 17, 2008 11:13 pm Post subject: Re: Flight Report andQuestion-701/Engine Failure |
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Joe, I havent recorded test data for engine shutdown at full angle of climb speed attitude, but I previously have done this in other ultralight and a C150A I used to own, from a safe height and prepared for a spin. Hope I didnt mislead too much about that, but in most situations with no propwash I am slightly nose low with elevator on the up stops and it took me a while to get accustomed to the pitch vs power effects especially during landing. I normally do climbout and approach at 50 Kts to keep everything solid and drama to minimum.
I run at 34% MAC normally which is near full aft cg limit in fact I was considering closing the rear baggage extended area to standard to prevent me getting too much aft. I have divided it off with bungee cord and only stow sleeping bags etc. way back.
http://youtube.com/watch?v=LIi5mQ9XUSM
Ralph
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