Christian Holmstedt
Well-Known Member
- Joined
- Jun 14, 2014
- Messages
- 63
I haven't been on here in years but I went through my old RC stuff the other day and found my half-built stash of stuff and tons of files with ideas and concepts.
Big plans back then to get into FE tunnel racing. Got a PX-300 (?), nice kit, but it was never finished. Got all the cool telemetry stuff too. I had plans for a custom hull that also never materialized. The paper design got quite far but nothing got done. One thing that actually got done was a custom 4 blade propeller. This was 5 or maybe closer to 6 years ago and it's been sitting in a box ever since.
It's designed for 3.50 cc Nitro and P Ltd/P Spec/ P Class Fast Electric Outboards. I read up on what basic size and characteristics racers used used at the time but since no boats were finished I never got to actually try it.
I have no idea how it performs. It might be way too big and hard to drive...
It's designed from scratch with all parameters calculated in a spreadsheet and had it made by a 3D printing service out of bronze. It's a 4-blade cleaver with the following specs:
Diameter: 42mm
Pitch: 55mm
Pitch/Diameter ratio: 1.6
Rake: 20mm
Pitch progression: 5mm (leading edge pitch is 50mm, final pitch is 55mm)
Cup: 23mm (pitch at the very trailing edge is 55+23mm)
Since it is a lost wax casting the final prop is slightly smaller than specified. I think the diameter is closer to 41mm.
It fits on a regular 3/16" fitting but due to shrinking it took some work to drill it out to fit.
I'm still itching to know how it performs so I'm thinking about lending it out to someone to have a go at it.
The guy/gal trying it would have to have their tunnel stuff together and running fast already. I am interested in performance numbers such as speed, acceleration (data logs) and over all drivability/feel of it compared to propellers available today.
It was quite expensive to have it made (~$60) so the main thing I am asking is to get it back undamaged and in a reasonable time. It's all about the honor system, if you know what I mean...
I will ship it to you at my expense. You do the test runs and post results here and ship it back to me (you pay shipping).
Are you interested?
Post some pics & stats of what you run now and we'll see what can be arranged.
Attached are a few pictures of it mounted on an OS lower unit in its raw unfinished state and pictures of it after sharpening and balancing was done. It's not perfectly balanced but I think it will be good enough.
Big plans back then to get into FE tunnel racing. Got a PX-300 (?), nice kit, but it was never finished. Got all the cool telemetry stuff too. I had plans for a custom hull that also never materialized. The paper design got quite far but nothing got done. One thing that actually got done was a custom 4 blade propeller. This was 5 or maybe closer to 6 years ago and it's been sitting in a box ever since.
It's designed for 3.50 cc Nitro and P Ltd/P Spec/ P Class Fast Electric Outboards. I read up on what basic size and characteristics racers used used at the time but since no boats were finished I never got to actually try it.
I have no idea how it performs. It might be way too big and hard to drive...
It's designed from scratch with all parameters calculated in a spreadsheet and had it made by a 3D printing service out of bronze. It's a 4-blade cleaver with the following specs:
Diameter: 42mm
Pitch: 55mm
Pitch/Diameter ratio: 1.6
Rake: 20mm
Pitch progression: 5mm (leading edge pitch is 50mm, final pitch is 55mm)
Cup: 23mm (pitch at the very trailing edge is 55+23mm)
Since it is a lost wax casting the final prop is slightly smaller than specified. I think the diameter is closer to 41mm.
It fits on a regular 3/16" fitting but due to shrinking it took some work to drill it out to fit.
I'm still itching to know how it performs so I'm thinking about lending it out to someone to have a go at it.
The guy/gal trying it would have to have their tunnel stuff together and running fast already. I am interested in performance numbers such as speed, acceleration (data logs) and over all drivability/feel of it compared to propellers available today.
It was quite expensive to have it made (~$60) so the main thing I am asking is to get it back undamaged and in a reasonable time. It's all about the honor system, if you know what I mean...
I will ship it to you at my expense. You do the test runs and post results here and ship it back to me (you pay shipping).
Are you interested?
Post some pics & stats of what you run now and we'll see what can be arranged.
Attached are a few pictures of it mounted on an OS lower unit in its raw unfinished state and pictures of it after sharpening and balancing was done. It's not perfectly balanced but I think it will be good enough.