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Permalink Reply by Bob McDonald on November 1, 2010 at 8:16pm

The CH750 kit supplied wings are 3 ft longer than the CH701. The elevator and horizontal stabilizer are 1 ft wider than the CH701. The fuselage is 10 inches longer than the CH701. The airframe is larger and heavier with an empty weight around 150lbs heavier than the CH701. I have VG's installed on the underside of the elevator. To appreciate the effect of VG's watch Bob Jones video on Utube of flying his CH701 in Alaska with VG's installed.

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Permalink Reply by David Tanner on November 2, 2010 at 1:06am

I have one of the very early CH701 with Rotax 912UL 80 HP engine.

I used to fly at about 65 knots and used 17 litres per hour of Standard unleaded gas. I removed the draggy slats and replaced then with a row of VG's along the top of the wing. Fuel consumption at the same speed went down to 14 litres per hour. I also put a row of VG's along the bottom of the elevator( I may have been the first one to do so) and it now has much more authority. I can now actually pull it into a stall with power off and the power on stall is more manageable without the sudden left wing drop. Rate of climb has also increased by a considerable amount.

David Tanner
vk3auu@dcsi.net.au

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Permalink Reply by Sarah Ashmore on November 2, 2010 at 7:29am

Try this link for StolSpeed Aerodynamics, a manufacture of wing VG kits ($97 US) in Australia. If you go through all of the links you will see reference to adding 2 feet to each wing and replacing the slats with VG's. The claims are it wil cost maybe 1-2 kts on stall but gain 8-10 kts in cruise. Those figures are for the CH701 but should apply to the CH750. In a CH750 the wing extension is probably not as usuful. For what it is worth I plan to go with the VG's and leave the slats in the bow they came in as I am really looking for a high wing, all metal LSA and not a STOL aircraft.

http://www.stolspeed.com/slats-v-s-vgs

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Permalink Reply by Hank Optland on November 5, 2010 at 2:59am

It would be really nice if Zenith themselves would offer a CH-701-VGEW version ...Vortex Generators, Extended Wings.

In my opinion, if Zenith could offer such an option to the ultralight buying public, they would be able to meet the competition from other light recreation aircraft manufacturers head on, e.g, ICP Savannah.

Such an option would especially be useful in countries such as Australia and New Zealand where the MTOW of "ultralights/microlights" are limited to 544 kg, counting the CH-750 out because it is too heavy for this category. Offering such an option would also extend the life of the CH-701 for another decade or more.

It may in fact be possible to merge the extended wing technology (and some of the other nice features) of the CH-750 with the enhanced CH-701 that I'm writing about here. Hopefully, the VGs and extended wing options would be possible at no great increase in costs.

I remember the excitement when bubble doors came along as an option, giving Zenith CH-701 users increased shoulder space for minimal additional cost. I believe the number of CH-701 buyers would significantly increase if the two extras mentioned in this post became available as low-cost options.

What do you think, Mr Heintz?

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Permalink Reply by Dennis Mitchell on April 2, 2020 at 12:54pm

I realize the original post was ten years ago so getting a response is unlikely. I just bought a 701 partially completed kit. The wings are extended 20 inches and I have a bunch of VGs from StolSpeed. The wings are fabricated already but there are no inspection panels so I may remove some rivets so I can open them up and inspect the modifications, basically how the extension was made and the quality of work.
Has anyone seen plans or instructions for extending the wings? Is there a splice in the main spar? If so how and what materials are used?
Thanks for any advice..
Dennis M

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Permalink Reply by Ralph Powell on April 3, 2020 at 8:18am

Dennis,

Have you used an endoscope for inspections, yet? A half inch hole and pop in plug for the snake and you are in business. I purchased one this winter and am still finding new uses for it. Sometimes it’s great, sometimes it may be easier to remove some rivets.

HomeBuiltAirplanes.com recently had a write-up on spar theory that may help you understand the impact of adding the extension. The author appeared to be very knowledgeable, but subject is over my head. 

Good luck!

Ralph

N750RP

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