skaliwag

My Feedback: (1)

I know it has been discussed ad nauseum but what is the preferred prop for the the trusty Cox.
I seem to remember an APC 4 X something was popular.
A customer is buying a built up wing Scalpel and needs prop choices.

MJD

My Feedback: (1)

4.2x4 is the standard go fast APC sport prop for 1/2A's. The 4.5x3.5 is similar, a hair more blade area and a hair less pitch. 5x3 for more pull, not as speedy, but great "all round" .049 performance. Good test flight prop as well. If the prop starts with 5.5- or 6-, the last number should be 2 or 3, and save it for a slow draggy airplane.

That's my $0.02.

aspeed

The control line Mouse race guys are using the electric APC 4.75 - 4.75" last I heard, as it gives the best speed and mileage as well. They are using the reedies. Rotary valve engines, a 4 1/4 - 4" is a good standard to start at as mentioned. Speed and acrobatics play a big role in choice.

Pond Skipper

APC 4.75 - 4.75E is a good choice for a reedie.

airraptor

My Feedback: (66)

APC has a 1/2A prop that is a 4.2x4 with small stiff blades but it may not be enough load but should turn over 21,000 on a black widow if I remember correctly

Pond Skipper

Carbon mix HQ Prop 4x4.5 (speed tip) out performs that prop within the
power range of all Cox .049 engines.

airraptor

My Feedback: (66)

where do you buy those?

Pond Skipper

HQ 5x4.5
http://www.ebay.com/itm/121953933452...%3AMEBIDX%3AIT

HQ 4x4.5

http://www.ebay.com/itm/121953933420...%3AMEBIDX%3AIT


Here is the 4x4.5 in action

https://www.youtube.com/watch?v=7IaQ4o_qXZ8

airraptor

My Feedback: (66)

I went to APC today and talked with Robert. I picked up a prop to test out for 1/2s. The problem I have is I dont have anything to compare against. So if you could post some numbers of that prop on a Black widow or TD .049 or TD .051 that would be nice with COX fuel. Also pond shoot me a PM and maybe I can send you two of these props to test your self.
This prop I will test is a 4x4.5 E prop for multi rotors. I think it will be a lot of load but I will test next week. I have a Q40 champ race this weekend.

Pond Skipper

I have done numerous APC prop tests.. the thicker airfoils at the hubs rob
a bit of power from small IC engines. The E style have very aggressive
pitch at the hub and rob power to from the low torque small IC engines
I use back cut on the blades to offset rpm loss and has been fruitful.

Here some numbers for small IC APC props.



Last time I ran a TD .049 was with a 4.1x4.1E with back cut here is the results:
https://www.youtube.com/watch?v=5bCto2zdGUY
https://www.youtube.com/watch?v=5bCto2zdGUY Published on May 7, 2016
TD .049 /SPI / Throttle Sleeve Ports Allow SPI function / Prop 4.1 x 4.1N / 30% Nitro
Static 24,790 rpm / 7.4oz thrust / .127hp / 94.74w / 96.2 mph
Unloaded 30,492 best on Vid 1 / 118.4 mph per prop calc.
Doppler reading has it at 117mph per pass at 1:47mins into the vid.

MJD

My Feedback: (1)

I was curious about the 4.75x4.75 so I ran one on the front of a good running (really) Dragonfly on 25% and saw 17,700. For S&G I ran a 3 blade 4x4.5 drone props with narrow blades.. 23.6k. Brushed the prop on my jacket and spit a blade too! Not touching that one again, but the size was appealing.

Pond Skipper

You should try the carbon HQ's tough props.

MJD

My Feedback: (1)

Yeah I know - this was just a pack I scooped up out of curiosity from the LHS. They looked kewl so I grabbed a pack.. no scientific endeavour involved.

From the little I saw there I'll be paying more attention to the small APC E-props re 1/2A's.

aspeed

The 4.75-4.75 would give you 85 mph plus maybe a bit more if it unloads in the air. Pretty good for a reedy. I think the reedies float at about 18,000 rpm, and that is their powerband. I do have to laugh at the reedy and speed being used in the same sentence. The thin blade papers out to 103mph, but I doubt that.

Pond Skipper

I would recomend the Carbon APC 4x75x4.75 big drop in weight for more rpm and thinner.

Here is the only carbon, nylon HQ prop I broke down wind out of fuel tried to milk it the wind caused a
violent tip stall smack straight down into a hard dirt patch this summer. As you can see there
is plenty of meat on the bone.