I took the slats off to try to get more cross country speed and I was amazed with the difference, 12% more speed. There was no change in take-off or landings. Most of the flying I do is long distance and using the standard airfields. How can I get an approval to fly the aircraft without slats ?? For me to be legal here in New Zealand, I need an approval from the aircraft designer. Any help will be appreciated.

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Thats pretty cool.  What is the past and present speed.  And no difference in take off??? The slats are a big part of the STOL.


I am scratch building a 701 and never intended to put slats on it. I would be interested in the before and after performance numbers of your aircraft. Also what engine, empty weight, etc.

   I think if you e-mail Zenith and ask for permission, (in writing) to fly the 701 without slats that they would do that for you. Right now they are probably pretty busy cleaning up the wreckage of their aircraft after the storm at Sun N Fun.

Good luck,


Hi Bob and Jesse

These are the figures of my flights.

27th of March 2011  ZENAIR CH701                        
Flight test with and without slats.                       
Course : triangle from Motueka -  Kaiteriteri - 5nm east to sea - back to Motueka. 15 nm miles.                       

With slats :                        
Climb 55-60 kts, 300-500 fpm.    Landings : 50kts over the fence and flare out @ 45KTS   
Without slats :                        
Climb 60-70 kts, 500-800 fpm.    Landings : 55kts over the fence and flare out @ 50KTS   

Indicated sp    Indicated sp    GPS speed    GPS speed
with slats       Without slats    With slats    Without slats

80                 80                     71               70
80                 90                     70               74
70                 90                     65               81
78                 85                     71               80
80                 85                     72               80       
78                 85                     71               82       
80                 85                     71               82       

78.00            85.71                70.14          78.43        Average

Long flight test. Motueka to Paraparaumu across the Cook Strait around 105 nm one way.                               

With slats :    Motueka to Paraparaumu 1 hr 45 min                       
                    Paraparaumu to Motueka  1hr 50 min                       

Without slats :    Motueka to Paraparaumu 1 hr 30 min                       
                         Paraparaumu to Motueka 1hr 25 min     


I would like to fly the aircraft without slats if I am allowed to by Zenith. I shall contact them  in a week or

two. My engine is Jabiru 2200 80hp standard. On all above flights, I was loaded to maximum, full tanks

and two adults etc.               

Ck The CG. Removing the slats changes the cord.

This may help, he states that there is no problem from an design stand point.


As for cord, I don't think they create any lift, guys who remove them say no trim changes, but they do weigh I think 14lbs, so CG will change a bit.

some 20 yrs ago i flew an CH701 equiped with rotax 503,two grown adults passenger NO SLATS at all and the plane STOL performance was AMAIZING,i believe the result of less weight from not carrying slats seems to compensate for less drag on cruise,Take off , and land in fact i haven"t try an CH701 with slats yet

The changes seem plausible, and there are some 701 flying in Australia like this, and I strongly advise you read up about adding VGs - obviously the Stolspeed from Aussie would be the easiest to do. They will probably be able to tell you the Australian acceptable certification that these examples fly with, as for NZ registration it must meet ANO 95.32, 91.55 or 101.55 - unless you want to operate it as an experimental category, that is.


So to your question as to getting approval in NZ to operate as a class 2 microlight,


first go to CAA website and read Rules part 103 and Advisory circular AC103.

You will find the statements that any modification that may affect safety requires a modification approval and part of the test of the approval is that the aircraft still complies with its original basis for certification which was stated in the original registration application form CAA 24047. For your aircraft this basis is most likely TP10141E. Even with a letter from the manufacturer stating that it is safe to fly without slats does not confer continued compliance with the design standard TP10141E, therefore I suggest your easiest way to revalidate the flight permit will be to re-register it under the ANO compliance rules from Australia.


Your other option is to have it re-tested by an approved test pilot, which will be very involved, effectively you become the designer of a new model of aircraft. In any case, the model designation should change and all the placards and speeds need recalculation.


I hope this helps (probably not what you wanted to hear), you might like to contact   




Thanks Ralph, sounds scary . . too much mucking around. I might sell the ch701 and buy something faster for the long distance flying. The aircraft flies better without the slats, landings are 10/10, but if it is going to be too much hassle to re-certify, than plan B will come into action (sell it).




Becarefull with the : something faster for the longest flying, thats where i came from and believe me its quiet EXPENSIVE

for an single pilot budget

Thanks Nelson, what did you use to fly before ch701 ??? It is a pity that I can't fly without slats here in NZ.
its an C172 RG,very nice and way fast cruiser but if the whole plane and operation  cost goes to pilot only, she can easy melt your credit card

Shafid, don't be put off by suggestions of needing letters from the manufacturer and going cap in hand to CAA. Remember it's a microlight and not an amateur built aircraft. The requirements are considerbly less for the type of minor modification you are proposing. My CH701 is highly modified from the original with retracting leading edge slats, different wing profile and the 120hp jabiru engine. When I applied for certification is was as simple as stating NZ103 as the certification basis. Nothing else was required and the test flying phase was still only 10 hours.

Talk to Rex Kenny from CAA as to the requirements before you go and buy a Cessna 177RG. You will be surprised at how simple and painless the modification process will be. There are a number of ICP Savanahs flying in NZ with the slats replaced by VGs and still fly very nicely I understand.


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