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-   -   Do Conards provide lift in level flight? (https://www.rcuniverse.com/forum/aerodynamics-76/11673103-do-conards-provide-lift-level-flight.html)

mikes68charger 12-19-2019 01:54 PM

Do Conards provide lift in level flight?
 
So as the question states, do adding conards to a jet add lift thus changing the CG?
https://cimg8.ibsrv.net/gimg/www.rcu...ed455f3210.jpg
https://cimg9.ibsrv.net/gimg/www.rcu...11eed80c86.jpg
This is a NASA F15 they used for STOL testing, apparently they took F18 elevators and made the big Conards on the F15

I'm currently Restoring a Byron F15, and this is definitely odd and was thinking of adding this feature to my build, but worry about CG changes

allanflowers 12-19-2019 03:00 PM


Originally Posted by mikes68charger (Post 12570666)
So as the question states, do adding conards to a jet add lift thus changing the CG?
https://cimg8.ibsrv.net/gimg/www.rcu...ed455f3210.jpg
https://cimg9.ibsrv.net/gimg/www.rcu...11eed80c86.jpg
This is a NASA F15 they used for STOL testing, apparently they took F18 elevators and made the big Conards on the F15

I'm currently Restoring a Byron F15, and this is definitely odd and was thinking of adding this feature to my build, but worry about CG changes

I wouldn't know about the full scale plane you are referencing, which might have lots of computer power to control things, but on a model you better take a different CG into account if you want it not to instantly crash. The typical canard surface carries at least the same wing loading as the main wing.

rgburrill 12-20-2019 04:41 AM

Even high bypass turbofan nacelles provide some lift so I would certainly assume so.

ahicks 12-20-2019 05:21 AM

Agree on the lift, there will be some, but IMHO, how much is going to depend on it's angle of attack, especially as compared to the rest of the plane. Figuring the CG might be tricky. At take off and landing speeds the canard will no doubt have a lot of lift. As speed picks up, maybe not so much?

Might be a neat project, but I think I'd be tempted to add a canard to an inexpensive foam EDF to do some initial testing. That should be able to guide you on a bigger project.

allanflowers 12-20-2019 02:01 PM

Using a foam EDF for testing would be a great idea, maybe along with some simple chuck gliders. A lot depends on whether you would still use the model's existing elevator for pitch or these new canard surfaces (probably the worse option).
The balance of the plane should not vary depending on speed and load, at all. If there is an effect at one speed, it will be there in others too.


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