Bruce Tharpe Engineering Flyin' King

[Vince53]

Here's some photos of my recently completed BTE Flyin' King. The way I fly these need to be taken before the maiden flight. I live in Michigan and it'll be a bit yet untill the snow clears but I'll be ready.

This was made from a beatifully cut kit, the first plane i've built this big. No laser cut parts in the kit but the fit and quality is as good as anything I have worked on before. The pieces are machine cut and sanded with help of templates. Take a look at the web site about Bruce's history and scroll down on the first page and check out the four trainers he built for NASA.

http://www.btemodels.com/index.html

On to my project, the 80.5" Flyin' King. I'm a great believer in high voltage setups with inrunners and gearboxes to turn large props and achieve high overall efficiency. Some of the old stuff is pretty inexpensive since the availability of large outrunners. Here's what I have set up:

Maxcim Neo-13Y motor
MEC Superbox Ratio 6.4:1
14s M1 A123cells
CC HV45 esc
All up weight 12.2 pounds, 195.2 ounces.
Hitec HS6635HB servos, one high torque servo for flaps
Larger landing gear from TNT
6" Kavan inflatable tires
RX power from 2 5cell packs with independant switches
The receiver will be a Spektrum AR7000 (just got it back from a firmware update for Quick Connect. It also works with the Spektrum information module)

[Dereck]

It'll fly great! Bruce is one of the best sports RC designers around - we had a Flyin' King around DC for a while, IIRC, Astro 40 or 60G cobalt and an obscene number of Big Round Jugs - 24 to 30. Flaps too. Flew around great.

Be interested to hear how you get on running your MaxCim on a sensorless ESC. I was using MaxCims back when it was either MaxCim, with superb speed control and a high voltage BEC, or Aveox with ESCs that were basically complicated on/off switches - though they did catch on eventually.

Then life "improved" to sensorless ESCs with jerky switch-ons to high idles. Outrunners, with short attention span instruction manuals were another 'improvement' over easily changed gear ratios. Buy the wrong motor, all you have to do is buy another motor - much easier than changing a $10.00 pinion ;)

Isn't progress great ? :rolleyes:

[Vince53]

Dereck,

I have run this Maxcim with the sensored controller in an Lt-25 and the low speed control was incredible. You could start it out slow and count the rpm's. The Maxcim works fine with a sensorless controller, you just lose all that low speed smooth startup.

I have a stock of home made gearbox shafts. Much easier than getting a motor shaft replaced in case of a poor landing.

Vince

[Dereck]

Hi Vince
The one thing I never had the nerve to try with a MEC box was modd'ing the shaft from an Astro cobalt 05 type gearbox to fit. It's the right size and threaded to just bolt a prop on - and accepts an OS spinner nut, which are really nice bits of work. But the Astro shaft is alloy and would have been prone to bending.

The MEC box with the later 1/4" shaft is far better than the original 3/16" shaft version - I bent one of them once when my 20 cell Four Star ran into a patch of tall grass! Used to take a couple of spares to flying sessions and got quite good at field-swapping them too. The 1/4" shaft - I don't recall ever bending one of them.

The MaxCim ESC was superb for speed control, and I plan on continuing to use the one I have left. Tom Cimato was a working pro in the electric motor speed control industry - he actually had work flying on the space shuttle - and reckone sensorless was what you used when what you mostly wanted was 'cheap'. Will try running one of my motors on a sensorless, from what you say. It's better than them sitting around - they have survived some unplanned arrivals better than their ESCs.

Regards

Dereck

[twest]

I'm interested in how that gearbox holds up at that power level. I will be using that gearbox with an astro 40 brushless, 8s a123, 60 amps in a staudacher this spring. If the mec gearbox doesn't hold up, I will need to use one of the 'innerdriven' gearboxes.
The choices of higher power gearboxes have decreased with the popularity of outrunners.

-another gearhead

[Kou]

twest:

I have been using the MEC on my Venus 2 with 7S2P A123 turning APCE 16X10 pulling about 70 amp static. Seem to work OK. I am now working on a 2M Sword using the same gear box turning 18x10 and 19x12. It seem to work on the bench but have not flown the plane yet.

I just check the MEC website, it seem to me that they have discontinue their Monster box. I never use a Monster box but was planning to so that is too bad.

MK

[KOMET 44]

What prop size??
KOMET44

[Vince53]

I can't be positive since the spinner partly covers it, but it looks like a 6.4:1 ratio with a 14x10 APCE prop. That is subject to change after flight testing. I just weighed it; AUW is 12.2 lbs, 195.2 ounces. If the weather gets better I'm hoping for a maiden later this week.

Vince