Need help with these specifications

R

RedGuy

New Member
Hey everyone, I've got a dilemma. I'm in a quad-copter competition and the specifications look very odd.
b. Rotors
i.Maximum length (tip to tip) = 6 in.
ii.Metallic materials are not permitted.
iii.Rotors must not be sharpened to a point.
c. Motors
i. Maximum angular speed at rated voltage (no load) = 7200 rpm.
ii. Maximum propeller to motor gear ratio = 5.
d. Power:
i. Maximum output voltage = 24 V.
ii. Maximum capacity = 2400 mAh.

Simply, with those rotor sizes and that maximum RPM, we don't see any way to get lift on this. Gearing is not an option for my team. We have a 250 quad kit with a 2 cell battery, 920kv motors (aprox. 6600 RPM), and 5-inch 6-bladed props and we get no liftoff. Some insight would be greatly appreciated! This is for the Science Olympiad Quadrotor event.
 
RedGuy, let me start with saying I have never raced quadcopters and I know enough about quadcopters to be dangerous. This said, I'm an old time RC aircraft guy and I am also a retired engineer with aviation background.

RC props and even real aircraft props come with a diameter and pitch number. You stated you have 5 inch props, do you know what the pitch value is? Whatever you have you may need a higher number to allow enough bite. The number of blades could also be an issue. Propeller efficiency goes down with increased blades as a general rule. A two blade 5 inch propeller with a larger pitch might get you where you need to be.
 
I've recently started using up to date parts & have noticed considerable weight reduction.
Micro cameras along with vtx & antenna that weigh the same as a cloverleaf.
Maybe you need to upgrade.
 
IMG_20180311_203307292-600x1068.jpg
It's working but I just need to check its range @ 50mw. If I can get 600m @ my spots then these are my new goto vtx.
£24 =1g
u.fl cloverleaf = 3g
Runcam sparrow =4.6g
9g fpv kit. A TBS triumph Weighs more.
You probably know this being a racer but I thought I did throw this out there.
But 2S lipo & 250 frame is a mismatch.
Unless it a 5" floss, like matchstick arms.

Is this a race competition.
It does sound odd.

How long you been flying for?
 
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