Build - BMJR Fiasco

Started by msatin, March 06, 2023, 08:55:57 AM

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Frank v B

#15
Mark,

Looks great to me as a charter member of the 50/50 club*

re: your "I have had a lot of trouble with this, as the hinge always would get crumpled or the fabric would come off as I tried to insert it into the slot"

2 tricks I use:

1) after you cut the balsa with the sharp end of a pointy #11 blade, turn the blade around and do a few passes with the unsharpened end.  It scrapes the joint open to turn a slit into a slot.
2) cut off the 4 pointy corners on each CA hinge so it does not snag as you push it into the slot.  It funnels the hinge into the slot.  See thumbnail photos from my Guillow's B25 build post about cutting the corners off CA hangs. If you wish to enlarge https://temac.ca/smf/index.php?topic=7745.60

This usually works.

Frank

* 50/50 rule- if you can't see the mistake at 50 feet and 50 km/h don't waste your time fixing it.   ;)
"Never trade luck for skill"

Gregor77

Mark, you may want to up the pitch on the prop, my experience is that a 5 pitch is going to do nothing to move the plane.  Even a 6 pitch is not enough, 7-10 pitch are good, but do a watt test to make sure it doesn't draw too many amps.

Example:  6 pitch was used for nitro planes as far as I can tell, mainly so idling they don't start flying away.   The LT40 I have has a 6 pitch 12" prop and its terrible, I am at 3/4 to full and its barely moving, plus the battery lasts a good 20 mins.  I would rather have some extra horse power and pull and less play time.

As far as electric, you just need to fly nice at 1/2 throttle and the rest if you want to be sporty with it.   

My 2 cents!

Awesome build by the way!


msatin

Thanks George.
The most important piece of advice I can give to anyone interested in building, is to not hesitate to ask for help.
This club has an abundance of talented people who are always available to provide guidance.
You never fail until you stop trying

msatin

Interesting observation Greg - Thanks!
I've never measured the amp draw on any of my planes. I guess it's time to start.  :D
I think I will bring several props, based your pitch recommendations, to the maiden, and select the best matched
You never fail until you stop trying

Michael

The specifications for the motor you are using recommend a propeller with 9" diameter / 4.5" pitch.

If you use a prop with 10" pitch, I guarantee you that something will burn.

Your original choice of using a 10/5 propeller is a reasonable start.
Michael

msatin

Thanks Michael.
I think that's the correct path.
Start with original choice, and have a couple of other options to test if necessary
You never fail until you stop trying