Replies to This Discussion

Permalink Reply by Matt Pope on July 5, 2023 at 8:40pm

I'm assuming you're referring to the 701 here? 

I'm not sure about the kit parts, but for what it's worth, here's my understanding of the change from 30 to 15. This is just from reading between the lines in various places (maybe someone else can confirm or correct this?). The 701 was originally designed to have 30 degrees of flaps, so 30 is structurally safe, but pilots weren't prepared for the rather extreme nose-down attitude and steep approach required to maintain energy in a power-off approach with 30 degrees of flaps. They would raise the nose to a more familiar approach attitude and the resulting high sink rate and low airspeed meant they didn't have enough energy to flare, so they had hard landings, which they blamed on the airplane. Since the customer is always right, the maximum flap deflection was reduced to limit the amount of trouble people could get into.

Here's an old post that gives advice for working up to landing with 30+ degrees of flap in the 701: http://www.zenithair.com/kit-data/701-ms.html

People are winning STOL competitions with 15 degrees, so unless you need to make really steep approaches to clear an obstacle at a very short field, then 15 degrees is probably plenty. Thirty degree flaps should be safe as long as the pilot learns how and when to use them and respects Vfe... definitely check that with Zenith first though if you're considering making yours with 30 degrees.

• ▶ Reply

Permalink Reply by ExpColt on July 11, 2023 at 1:24pm

Matt yes it is a Ch701 sorry about that I forgot that piece of information. I will check with zenith if I decide to go with 30° thanks for the link and information. I'm curious to find out if I can make the slot long enough in the stop to have a 15° and 30° position? I do like the upgrade flap mechanism zenith offers and I'm still considering that as an option but I feel like I could put that money to better use at this point and get the plane flyong sooner. I can always do upgrades later

• ▶ Reply

Permalink Reply by Jim and Amelia Isaacs on July 14, 2023 at 1:06am

https://www.homebuiltairplanes.com/forums/threads/what-i-learned-ab... 
There’s additional info in Joe Spencer’s thread above regarding 30 degrees of flaps and other 701 pilot experiences when using them. I can’t find any official Zenith information explaining why they eliminated the 30 degree setting from the original plans but from what I’ve read elsewhere it’s likely as Matt said, safety reasons that arose during extreme STOL operations as well as a few other normal operational issues that were not desirable.
There is a forum on this website for just the 701, if you search that one you will find other comments about flaps 30 vs. flaps 15. Also for any future new topics regarding your 701 that may produce more replies than posting here on the Open topics forum.

• ▶ Reply