Backcountry Pilot • Building a Zenith CH 701

Building a Zenith CH 701

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Re: Building a Zenith CH 701

Hi Tom, We took a look at using VG's because we thought there might be some advantage to that. But we decided to stay with the slats mainly because we wanted the inspection process to be as simple as possible and because the plane will be offered for sale after we get some time on her. If you stick right to the plans there tends not to be any questions. There were a number of decisions made on that basis.
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Re: Building a Zenith CH 701

I've stuck with the slats on my plane. While the improvement in cruise speed is claimed to be perhaps 5mph, I did not want to loose the margin in slow flight. I have no interest in trying to recover from a stall at 100 agl.

tom
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Re: Building a Zenith CH 701

Well, we got it done! Here is the group of us putting in the LAST rivet!
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The N number was added and we wheeled it outside.
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Since this thing takes off in 90 feet and we were only planning on taxing it, two of us got in to hold it down.
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Of course since we had to show it off to so many people we wore the battery down turning the Dynon 180 and lights off and on and off and on... So we had our first jump start before our first taxi!
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Here are the fearless taxi test pilots on their way to destiny!
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After a safe return from one end of the runway to the other we gave other people rides!
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So here it is!
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It came in a bit under $40K. We are totaling up the hours to build it now. The Jabiru 3300 engine starts with a half turn of the prop, runs really smooth, and is so quiet you can sit in the cockpit and have a normal conversation without headsets.

The bubble doors allow two beefy guys to sit side-by-side and provides a great view.
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We are going to add some dark green carpet to the interior. The cockpit panel is nice and clean.
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The paperwork is being filled out and we have to make an appointment to get it inspected. Then we go for first flight! Stay tuned!
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Re: Building a Zenith CH 701

Very nice! You guys will have a blast.
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Re: Building a Zenith CH 701

Rod, are you planning to sell it for only what you have in it, or are you going to add a profit for your EAA chapter or your group of builders? There may be a guy here locally who could be interested in it, but I have not mentioned it to him yet and I have no idea if he is ready to buy now. But he built half of a 701 once, and built 3/4 of a 601 before all the problems, and he loves the Jabiru engine.

Bill
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Re: Building a Zenith CH 701

Bill,

The plane was financed by my brother. The deal is that we have the fun of building it and then we get to fly it for a year. After that my brother will sell it and maybe make a little money. I have to tell you, we really did have fun on this project. We probably could have had it done in six months but it was really a chance to have a neat social project for the guys in the EAA chapter.
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Re: Building a Zenith CH 701

Skystrider wrote:Bill,

The plane was financed by my brother. The deal is that we have the fun of building it and then we get to fly it for a year. After that my brother will sell it and maybe make a little money. I have to tell you, we really did have fun on this project. We probably could have had it done in six months but it was really a chance to have a neat social project for the guys in the EAA chapter.


Good for you guys! All the way around...now thats aviation the way it is supposed to be. Enjoy! And send us tons of pictures along the way. [-o<
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Re: Building a Zenith CH 701

Monday, January 10 we had our FAA inspection and we passed with no squawks! What a surprise!

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Here are some finished pictures with the carpet installed.

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In this picture you can see the ELT installed and the Dynon remote compass in the upper right corner.

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We replaced the suction cups used to hold open the doors with struts.

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Building this plane with a group of EAA folks was a lot of fun! :lol:

Now we just have to wait until the snow melts off the runway so we can get a first flight in! [-o<
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Re: Building a Zenith CH 701

What do you mean, "wait until the snow melts"? I have a Federal nose wheel ski and one Federal regular 1500 ski for a deal at $300 for both. All you need is another 1500 and send Tim over to pick them up. I hope to see it next Oct at our Ohio Bush Planes (OH82) fly-in??
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Re: Building a Zenith CH 701

patrol guy wrote:What do you mean, "wait until the snow melts"? I have a Federal nose wheel ski and one Federal regular 1500 ski for a deal at $300 for both. All you need is another 1500 and send Tim over to pick them up. I hope to see it next Oct at our Ohio Bush Planes (OH82) fly-in??


Hahahaha! I am actually thinking about that! Unfortunately, Tim took a job with General Atomics working on Predator aircraft. He is now out in Palmdale, Ca!

And, yes, I intend to once again try to make it to your great fly-in if the creek doesn't rise like it has the last two years. (RATS!) #-o

I am thinking I should just fly out on a nice week end!
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Re: Building a Zenith CH 701

Congratulations on your inspection. A very good looking 701 and it should be a great plane with the engine choice.
Do you have someone that has flown a 701 for the test pilot? If not I may be able to offer some help to who ever does on what to expect from the plane.
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Re: Building a Zenith CH 701

Thanks for the offer dirtstrip! I am always open to any advice or tips you can pass along.

Another fellow in the area has a 701 with a 912 engine. He has been stopping in on a regular basis to answer questions and pass along info. There are four of us who are planning to go out to the factory to get a couple hours of instruction. I have been told by a couple of folks that since I fly a Maule the transition should be easy. It just gets off the ground faster! :wink:
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Re: Building a Zenith CH 701

dirtstrip, Savannah Tom and probably others here have far far far more experience with this type of aircraft than I, but in my one flight I noticed a few things that were different and quirky about the 701. Consider these factors and be ready for them on your flight if they happen:

1) The 701 had a lot of drag and not a large amount of mass. When you pull the power back, forward motion stops in a hurry and big vertical motion is right on it's heels. So IMHO fly a lot closer to the airport and a lot higher than what you could get away with in your Maule.

2) With the power pulled back, on a stock factory built 912 powered 701, there was a very pronounced buffet at 60 miles an hour. Now we knew that the actual stall speed of the 701 is down in the 30's, so it wasn't a pre-stall buffet. Doesn't matter why... but when you decelerated down close to 40 you did not feel the REAL pre-stall buffet (the airplane had been shaking for the last 20 miles an hour), so the stall came without a warning that you could recognize.

Good luck on your first flight Rod. Be conservative and suspicious of everything. The place where you fly the first flight will have a huge effect on what options you do or do not have in an emergency. Your home field may not be the safest or best option, listen to that little voice. Look at the flight path on takeoff - if you have a power loss or fire or something big, what would it take to get the airplane back down on it's wheels without skidding or flipping over or cartwheeling. Would you need to make any sharp turns, a 180 degree turn, or would you be able to have a smooth area ahead or slightly off to one side? Will you be able to concentrate 100% on the airplane, or will you have to give up 25% of your attention to a control tower or other busy traffic in the pattern?

Make sure you do the old-school model airplane trick of running the engine at full power with the nose held up at least 30 degrees. You would be surprised at how many fuel delivery and engine problems might be exposed by this ancient trick. Put the main wheels up on heavy benches or big blocks or something, and put the tail on the ground so you get a FAR higher nose-up angle than you could ever get in flight. Raise and lower the tail at various throttle settings including full power, until you have proven beyond doubt that your engine does not run any leaner, richer, or less reliably in these attitudes.

Do a sailplane pilot's "positive control check" just before engine start (after you have transported the airplane and/or reassembled it at the first flight location). Have people clamp their hands on both sides of each control surface, trying to RESIST the movement of the controls. Overpower them with the stick and pedals. During this check, LISTEN and FEEL through the control system for any noises, slippage, friction, or bending/deformation in any part of the control system when the forces are acting against control movement. (I can recite a few names of pilots who would still be here with us...)

When you take a quiet moment beforehand to pray for help to have a safe first flight, be open to the idea that God may have chosen to answer your prayer not by shielding you from having a problem when you are airborne, but by giving you the brain power and attention to detail (three days previously) to find where the Devil has sabotaged your aircraft :)

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Re: Building a Zenith CH 701

Thanks for the info Bill! You can never be too prepared!
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Re: Building a Zenith CH 701

Good advice from Bill and applicable on first flights of any aircraft. I will be specific to the 701 with my comments and what I know of it.
I did not have buffet on mine when closing throttle above stall. I have heard of instances where there was and I believe it may be individual combinations of engine rpm and props at work here. I will address this first.

The prop blast over the cabin and between the wings shoulders hitting the under cambered surface of the horizontal stabilizer allows the high tail of the 701 to respond instantly to throttle inputs by creating lift on the underside pulling it down. Prop blast or lack of it quickly affects the lift and control of the elevator. I suspect this is what is the cause of the buffeting some have noticed. It is elevator or stab buffet from either prop blast or blockage. A wide bladed, or three blade slow turning prop can block more air to the elevator than a stopped one will. Do not cut the throttle to idle when you have made the threshold but carry a little throttle right through flare and close it when the mains touch. Closing the throttle is going to end the flight. A little throttle will let the elevator act more like when the engine is off in glide. Carry a little rather than let the slow turning prop deprive the elevator of full effectiveness.

My advice is no flaps on the first flight.

The elevator really lifts the nose with the power in right at the start of the roll. The nose will come right up with power. To accustom yourself to this, play with the stick and add power with the brakes locked to feel the effect of power on the tail as it lightens the nose. Do not expect the brakes to hold you stationary at full power, at least mine didn't.

Next let the plane roll on the runway and add power with the stick back to raise the nose. It will not take much but feel the light responses of the stick as the nose comes up and you balance it on the mains while rolling then cut power back and see how the throttle lets the nose back down. When you have this throttle to attitude response in mind and you are comfortable with feeling the stick inputs the next step is to get some ground clearance under the wheels and then slowly cut power again to feel it settle back to the ground, nose high. The mains touch first then with easing the throttle back more, the nose drops when the elevator quits flying. Notice the high angle of attack that is the landing and takeoff configuration. It is steep and if not for having the upswept tail, it would be dragging on the ground. Also, as the nose drops the slots on the wing are no longer exposed to the oncoming air. Once the nose begins to drop the airflow through the slats vanishes quickly from the wing, the lift is gone and you are ground stable in the roll out, all at once. Couple the slat leveling that cancels wing lift with the full deflection rudder and you have got a very good crosswind ability in a light aircraft.

The 701 is a plane that will be off the ground shortly after the throttle is in. Climb out is steep but on the first flight don't test this. I posted a steep climb out in the 100hp engine shoot out thread from a 701 first flight. Don't do that. What was he thinking! I will talk about why.
I climbed at 60 mph. Flew at 70-80 and approached at 55-60. Forget the 1.3 of stall with this plane. Here is why, the climb out speed as well as the approach speed should be high. Bill mentioned it, with little weight, and high drag from the leading edge slats, speed decays rapidly and sink rate goes up when power is back or lost, especially on climb out. These things are what gives this plane its short landing, just be aware of it and know it will be there.

In the case of engine out, point the nose down and keep the airspeed up to the 55 approach speed, 60 is fine too (This is the no flaps approach speed.) Do not try to stretch out the landing. You will use this speed to carry you through the flare, as I said when you raise the nose for flare and touch down, the wing slats are more exposed, catch a lot of air and will slow you rapidly. The emergency landing is totally uneventful as long as you carry the approach speed. Remember nose down, get the airspeed up. The speed will bleed itself off fast at flare. This plane can land just about anywhere.

On normal landing, again approach 55-60. You should not approach with the throttle closed. Think airflow on the elevator. Fast idle is good. The prop at this speed keeps airflow over the elevator allowing the extended flare and lets you get nose high into something less than the take off attitude, then touchdown on the mains. When the mains touch pull the power back gently and the nose lowers, the slats level and the whole thing is done flying. Flights over all at once. Again very stable in the rollout with 7' gear and only 27' of wing with no lift left in them. The newer 701 can have an extended wing which might call for some adjustment over what I have stated. I understand the glide ratio is somewhat better. I think mine was less than 8:1.

When this plane stalls power off it will not buffet nor will it drop a wing. It is one of those planes that will almost flat fall at a high sink rate. I think the reason for this is that when it stops flying its sink rate increases to the point where the slats once again have airflow and the directed air from the slats keeps the wing flying and from falling off. It would be difficult to hold it in the stall but you would be losing altitude rapidly. It stalls, flies, stalls, flies all the way down. This would also be my conclusion as to why you should not use the 1.3 number for approach. The sink rate at this airspeed is too high and not how you want to touch down. Can't say it enough, keep the airspeed up on climb out and approach. As you get more feel for the plane then start on flaps. Full flaps steepen the approach to the point of ridiculous. With power off landing it is my opinion that full flaps make for a very steep approach and a very abbreviated landing, uncomfortably so that I wouldn't recommend it in an engine out situation.

The unique blend of throttle and control, sink rate and slats will become the tools you love in the plane. I think that influenced my decision to buy the Tundra with its steep approach ability. I spoke two nights ago with the man from Indiana who bought my 701 in Nov. of '06. He later sold it to a friend who begged him for it so he relented but shortly after buying it the friend died of cancer. He would now like to buy it back from the relatives. They won't part with it. He said flying with the eagles over the nearby power plant with his friend was one of the best memories he had. He misses the plane and I have to agree with him that it is the most fun plane I have ever flown.

(Note here. I have just read some changes on the 701 that were made since mine and of late. I don't know how much these will affect the flight characteristics that I have described. In addition to the extended wing I mentioned, there are now VG's available from the company for the under cambered horizontal stab and that is in keeping with the lowered air flow behind an idled prop. VG's may help extend elevator control at lower airflow over the stab, and with an extended wing would almost be a necessity to make the elevator stay in flight for at least as long as the extended wing. The other is one that I am sure yours and others all have now is the elimination of the last hole of flaps. The old full flap position was so steep as to almost be unusable for landing, certainly not for engine outs. These sound like good improvements. You are going to love flying this plane.)
Last edited by dirtstrip on Sun Jan 16, 2011 11:09 am, edited 4 times in total.
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Re: Building a Zenith CH 701

dirtstrip, Thanks for taking the time to pass on that information. I really appreciate the insights and I will be sure to keep them in mind for my first flights. Both you and Bill have provided some very specific recommendations that helped fill in gaps in my knowledge.

I find that having someone spend time writting this stuff out on the forum is more beneficial than a casual conversation because I can go back and reread what was said several times. That helps me retain and understand it better. Thanks again guys!
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Re: Building a Zenith CH 701

How about an update?
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Re: Building a Zenith CH 701

mr scout wrote:How about an update?


Haha! Well, we have made a lot of progress. We received the airworthiness certificate and placed it in the document holder with the W&B and registration. As soon as our tech advisor shows up, we are going to velcro it to the inside of the plane. In addition, and this is a big one, I took a 4 x 4 pressure treated board a foot long, cut it on a 45, drilled holes, attached rope connecting the two pieces, and with a large black marker wrote "N3701M" on it. So now we have "official" chocks!

Other than that, since January we have been sitting around waiting for two feet of snow and ice to melt off the hangar and runway. And I thought watching grass grow was exciting! #-o
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Re: Building a Zenith CH 701

What was your hour total and was that figure per person? I am thinking of building something just to putt around here. I was going to use the Pawnee but the guy that is covering the wings is so slow I think I may just sell it. Maybe I will put the Pawnee on Barnstormers and start over, I read the Savannah already has the holes sized is the 701 the same? Do you dimple them? It appears a guy can build a complete one in the time it takes to build a set of RV wings.
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Re: Building a Zenith CH 701

The work log book shows 977 hours total. Realistically, it was really about 2/3 of that, or 650 hours, because this was partially a social event. The 701 has the majority of its holes pre drilled. No dimpling was necessary as pull rivets were used.

In all honesty I would buy a 750. It came out after we were well into the 701. It is still LSA but it is bigger and better refined. Estimated build time went from 450 hours on the 701 to 350 hours on the 750. That is for the aircraft frame. The engine and instruments add time. The 750 will take less time to build and give you a better fit and finish.
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