View Single Post
Old 01-06-2021, 02:54 PM
  #13  
RKTLaunch
Member
 
Join Date: Dec 2020
Location: Texas
Posts: 90
Default

Originally Posted by quorneng View Post
RKTLaunch
For a vertical take off the total weight is not too much of a problem, it just has to less than the available thrust! However 'balancing' a plane on thrust is a lot more difficult.
If the plane is intended to 'fly' using its wings then the resulting wing loading does have an impact on the speed it has to move through the air.
This wing loading 'formula' roughly calculates the minimum flying speed.
"Awing
's stall speedin mph is approximately equal to 4 times the square root of the wing loading in ounces per square foot"
With a wing loading in the order of 53 oz/sqft the minimum speed comes out at about 29 mph.
Remember this is only an indication, the actual minimum speed depends on a number of parameters including it physical size. For a given wing loading the bigger the plane the better.
In addition this would be the speed that effective aerodynamic control would be lost so the minimum practical speed would be something like 25% higher.

At the moment your predicted wing loading is pretty high for the size of plane you propose.

I had originally considered rocket launching this model. I have a lot of experience at that. Then I looked at the cost of the rocket motors that would be appropriate. Nix on that. I think a sling-shot will do the job, but landing would be pretty difficult without slats and flaps, which of course....there's no way I'd build that into a model. I think what I have to do is weigh all the materials, before I make any final decision. I may play around with making the model bigger and adjusting the wing area. The added balsa and birch is small compared to the electrical. Again, I won't make those decisions until I order and weigh the materials.

In the '90s I designed and built a push-pull with twin queen-bees, only about 30 x 30". There was so much power, I just barely had to toss it and it had monster power. Free-flight and I did not damage to it. It landed flat in a soccer field, but I went on to testing wing design with rocket launching instead. Putting a small model 300ft in the air in a second and a half was a good way to test my experiments. I was successful, but I have some real adjusting for the EDFs....batteries, etc.

Last edited by RKTLaunch; 01-06-2021 at 03:11 PM.
RKTLaunch is offline  
 
Page generated in 0.06172 seconds with 8 queries