"Kollmann 2Buck Racer-X, Racer-T and Racer-V" Series - Page 2 - RC Groups
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Jul 20, 2017, 09:24 PM
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Yes, I have a CNC router and I just made the cut file to crank out 1 firewall plus 4 control horns. I used 1/16 ply. Here are photos of the finished cut and the finished pieces. I would be happy to cut more if you can supply me with some plywood. Although the 3D printed version may be the ultimate...
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Jul 21, 2017, 01:05 PM
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Sweet!


I'd be happy to pay for the plywood for a dozen sets and whatever you need for your time.
I also may have some "Nosen" plywood around here, I'll check.

I'll still do the 3D printed mount/firewall to try out but the foam/plywood will always be a lot lighter. and take 1/10th the time. Printers are SSSLLLLOOOOWWW.

Let me know.

-J
Jul 23, 2017, 01:22 PM
Registered User

Progress


I do intend on trying a "pitcheron" version because the build would be strong and simple and the control wires/horns could be deleted. Also, it would be a two servo airframe, hence lighter, and could survive a more radical clipping with the same loading and a cleaner airfoil. I just need to design a 50 cent way to pivot the wings. The build would be less conventional, but I think it might still be pretty easy.

I'm looking forward to some ribbon/combat with these too. They are so small that, even when you are trying, It's very hard to get two of them to touch each other.

We had two in the limbo contest yesterday, I struck the vertical steel pole Three Times! The third time finally dislodged the wing and damaged the turtledeck but it will fly again. These are tough little planes.
Greg made it under the minimum limbo a half-dozen times with the prototype.
Touch and goes with no landing gear are not something you see every day.

Here is a pic comparing the size and configuration...the cat always poses for the camera without being asked.
Jul 24, 2017, 01:50 PM
Registered User
Nice work, Joe.

I don't see a cat....

I do, however, see the fur covered bowling ball.........
Jul 25, 2017, 02:21 PM
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I printed up some power pods and horns if anyone needs some for a racer build.
-J
Jul 25, 2017, 04:22 PM
Registered User
what power pod file are you using?
Jul 26, 2017, 11:12 AM
Registered User
I tried a few.

The ones in the picture are a little thin for my tastes, but I bet they will work fine. they are under:
this link:

https://www.thingiverse.com/thing:633310

I tried the solid as well as the latticed, The latticed one is a bit weird to print, but would do nicely with PLA probably. I'm using ABS so I can post-print strengthening and smoothing with acetone.

This one looks a bit thicker and has no thrust angle and uses popsicle sticks instead of skewers

https://www.thingiverse.com/thing:1598145

The firewall working loose from the rest of the pod is an early failure mode on the original method of construction. Though it's an easy fix when it happens. I am hoping this makes the plane easier to build, with no Plywood to cut , and maybe a bit tougher.

I'll be designing my own nose soon so the firewall, mount (thicker) and a fairing that matches the spinner base will be all one part. Also the forward fairing as a separate part. Which is one of the more twitchy things to build
Jul 31, 2017, 12:49 PM
Registered User
I now have lots of plywood firewalls and horns (thanks to Richard) SO If anyone wants one or two , let me know. Also have some 1.5" two-blade spinners printed-up that fit the excellent GWS 5043 props.

I tested the V yesterday some more (until a VNE snap roll broke the rubber band on the wing) and it flew well but on the more rigid 5 x 4 bullnose prop it would really scream, but sag after a lap or two regardless of battery. I tried the GWS 5043 which is thin, flexible and cheap, and it flew at full throttle (pretty much) for over 10 minutes with no sag at all. Probably a tad faster than the 3-bladed 5/4 that had been the weapon of choice so far.

The crash, a full throttle tumbling cartwheel death splat at full speed, resulted in a couple of wrinkles and a bunch of dirt on the nose. I replaced the rubber bands and flew another couple of batteries. Just two rubber bands allows the wing to dislodge easily under crash loads, preventing too much damage. With four bands, the -T when it hit the steel pole during the limbo, did a lot more (repairable though) damage to the fuselage.

-Joe
Last edited by Joe Kollmann; Jul 31, 2017 at 12:56 PM.
Aug 16, 2017, 02:33 PM
Registered User
We had four of these up and "mock-racing" , which I guess what you call it when everyone is cutting corners and trying to figure out how low is "too low", last weekend. Had a few midairs, but everyone pretty much was able to screw-glue and re-rubber band to get back in the action. We've seen some pretty small wings, maybe 30% less area than the one in the plans I posted and they don't seem much faster if at all, but get quite twitchy with less wing. I bet at open throttle , despite different props, wing size/area, and the three different tail configurations there wasn't a half a lap total difference between any of the five airplanes we've had up and going. This is pretty cool because it all boils down to efficient flying and (once we have spotters) pylon cutting and maybe a little throttle management. The laps are in my opinion , a little faster with a reduced throttle just before turning, making for a smaller turn radius, and then gunning it down the straight in a shallow dive. WIth partial throttle , these things turn on a dime with the original semi-elliptical "racer wing". Something like an 8' radius at 90deg bank.
Aug 24, 2017, 12:37 PM
Registered User
FOUR IN THE AIR AT ONCE
Well...we've got a few of these built now. Seven, I think. In ten laps no single plane can lap another and the wings are between 100% and 50% of the design in the plans for the tiny racer. With less wing it predictably gets harder to fly but isn't significantly (if at all) faster. I believe the T-tail is the most stable and controllable and has lasted the longest. We've had three to five up and mock racing in winds up to 15KT with no problem. Here are a few pics

https://flic.kr/p/Y345y8
https://flic.kr/p/XM2uw9
https://flic.kr/p/WNyKaP
https://flic.kr/p/Y345zR
Aug 24, 2017, 12:44 PM
Registered User
mondofresh's Avatar
My Racer T is ready to maiden. I'm hoping the wind dies down this afternoon.

I went with an aileron-elevator only build. I did some reinforcement with 2m flat CF bars to strengthen the wing, rudder, and elevator.

One question - where should the balance point be? I put the recommended battery under the power pod and the plane seems quite nose heavy.
Aug 27, 2017, 11:43 AM
Registered User
mondofresh's Avatar
Here is my contribution to the growing fleet...

Tough to trim out, but I'm getting close to having it dialed.

I was surprised how easy it is to land this sucker. It slows down very nicely and doesn't have any nasty tip stall tendencies.

PROTIP: Joe is right, surfaces are very sensitive. Recommend dialing your rates down and adding lots of expo.

Thanks Joe for a fun plane!
Aug 29, 2017, 01:13 PM
Registered User
They do build pretty nose-heavy. especially with the V and clipped tail surfaces. I have a nickel taped to the tailcone of one of them. That said, they fly fine with the CG about an inch behind the leading edge which is only about 22% MAC I think this tames them down a bit. Ideal Cg is probably 1.5" behind leading edge, but we'd probably need to move the wing forward 1/4 inch to get that without adding a bunch of weight.
Oct 22, 2017, 08:17 PM
I want to fly everything!
Lance Nordby's Avatar
Hey Joe, I'm building one and I got questions.

What size are the push rod wires; .032 or .047?

I'm not a fan of belly floppers. If I come up with a landing gear design that can be retrofitted and I made enough for everyone would you guys be down with that? I would use a standard O-ring for the tires and create a 3D model of the hubs so they could be printed. ROG race takeoffs would look cool. You could also taxi back to the pits without having to wait for everyone else to get done flying.

I've always hated that unfinished look of the fuselage being open on the front. Can I fill mine in without everyone hating me? At least for that reason anyway.

Can you save a power pod for me? I forgot to get one from you last weekend.

And a firewall, and a spinner and anything else?

Is it alright if I change the shape of the wing and tail feathers a little to make it look a little different? The span and surface area would stay the same. I just want to put my stank on it.

I suppose it will be up to me to make a couple of fan inflated pylons. Or does someone have a good idea for these?

L.


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