|Sep 25, 2013, 02:22 AM|
United States, MN, Hubbard
Joined Jan 2004
Here are some pictures of my Calypso motor mount, cooling and the battery compartment.
I am not happy with the motor mounting right now and will probably remove the plywood box and put in standoffs so I can put a larger hole behind the motor for more air flow. Everything else comes down cool but the motor is hot enough that I can't hold my finger on it more than a few seconds.
The first picture shows the ( ugly) truncated spinner and lower cowl air opening. Later on I may try to duplicate what you did with your spinner. The ESC is straight behind the opening. The second picture shows where most of that air exits just below the wing. This is an oddity of the Calypso design. The bottom front fuselage is lower than the wing, probably because a pipe tunnel was supposed to be there and lead into a groove in the wing center section. You can see the back of the ESC if you look carefully through the air exit holes.
The battery slides into the front of the fuselage through the bulkhead at the wing leading edge. Balsa spacers glued to the sides keep it centered. Then a restraining former is slid into a channel on the fuselage sides and a foam spacer holds the battery forward, allowing space on the sides and top for air flow. That air exits at a hole on the bottom of the fuselage just behind the wing trailing edge.
None of it very sophisticated, but so far it seems to work well.
The large hatch helps and the plywood doubler than runs through the wing area was laminated to the balsa sides with some carbon fiber tow between them to stiffen that area.
I hope this is clear enough. I'm no great photographer.
|Oct 24, 2013, 07:13 PM|
Sorry for the delay.....Lost track of my own thread!!
Thanks for the pictures. It is interesting to see how you engineered your conversion. It seems simple and effective.
I am surprised you motor is coming down hot. It would seem like you have enough airflow. How big is the exit hole? I understand that the rule of thumb is that the exit needs to be three (3) times larger than the intake. Your intake would include the chin scoop and the spinner. You might want to check that. Also, how many amps are you pulling? How many watts? My Conquest set up runs at a peak of 67 amps so the motor and the battery are not working too hard. (1600 watts on a motor rated for 2000 and 67 amps from a 5000 mAh battery is only 13c.)
Thanks again. I am really glad to know that the Conquest inspired you.
|Oct 25, 2013, 04:50 PM|
United States, MN, Hubbard
Joined Jan 2004
No problem on the delay, I've been away or two weeks anyway.
I have a very large hole on the underside behind the wing. I've heard the same ratio and have used it on glow powered cowled in engines in the past. I am sure the exit is large enough.
What I think is happening is that the air flow through the motor itself is getting stopped or slowed too much . I think I need to remove the plywood box mount, put the motor on stands offs and get better access to a hole directly behind the motor. The hole is there but I think that air holes in the side of the box are perhaps too restrictive to allow it to be effective
.My Calypso is running at around a 62 amp peak according to the Castle ESC and Castle Link data logging, so just under 1400 watts.
I am new enough at larger electric motors that there may be no problem at all. I may be worrying about nothing. It is just that the motor is hot enough that I can't comfortably hold a finger on it for more than 2 or 3 seconds after the flight. The speed control is running under 103 F.
Any advice from more experienced electric guys like you would be greatly appreciated here regarding motor running temps.
It has become cold enough here in Northern Minnesota (30's F) that I won't be flying for a while.
Once I can fly it again, I'll try to have a friend with one of those infrared temp guns and find out what it is really running at. I think I remember reading if it is under 140F it should be fine.
Thanks for your comments and inspiration!.
|Nov 29, 2013, 09:57 PM|
So the Conquest IVe got published in Model Aviation. I thought the plane was worthy of the monthly Focal Point so I submitted it late last year. I got a plug in for the Classic Pattern Association while I was at it.
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