Hi Bob,
Magnificient looking twin, great job as always. I thought I would chime in since I just received a new custom timer Will designed for me to allow for the E-Flite .10 to .15 electric retracts. I had been trying to get these retracts to work with my Z-Tron Z.4 timer, but ultimately found out this timer will not work with these specific retracts even though there is a retract channel built into this timer. After speaking with Mike Palko and Sergio, it was determined the cause was probably an insufficient sized BEC. These retracts operate in the 4.7 to 7.4 volt range and draw 5 milliamps at idle and 150 milliamps in operation. There is only one BEC that will work with the Z-Tron Z.4 timer and it is only sized to power the actual timer and one retract servo. These retracts do not use a servo, the motor is housed in the retract assembly and the only BEC available for the Z.4 is not large enough to power these retracts.
I ordered a 10 amp Castle BEC to pair with the new Hubin timer and anxiously waited for it's arrival. Here is the test report I sent to Will earlier today with the results. Hopefully this may save someone a bit of time sorting this whole electric retract thing out. I know Will sells a timer with an included BEC built in, but I did not test that one, I tested one which requires an internal BEC. Not sure if the timer with the built in BEC will work with these retracts or not, perhaps Will might know.
"Hi Will,
It was kind of cold and a bit windy last Sunday, but Wayne, Sam and I went flying anyway and we got a chance to check out your new timer with the retracts. Everything performed flawlessly though I might certainly tell you a funny story about the first takeoff. We programmed the timer and ran it through a few dry runs on the ground without powering the motor and the retracts worked perfectly. OK, get the lines rolled out, plug in a new battery and give it a go.
We had programmed the RPM for the Plettenberg 25/12 at just over 9300RPM as a starting point. Wayne wanted to get a tach reading so we would have a reference for the timer though I protested a bit due to the 10 second retract sequence. Well, it did seem we could check it for a second or two and still have time, so I said OK, let's try it.
Wayne's grandson Sam was holding the plane while Wayne plugged in the arming switch and then activated the timer, tach in hand. The motor started and quickly came up to RPM for Wayne to get a tach reading whereupon I immediately motioned Sam to let the plane go just as soon as Wayne had exited the immediate area. Sam let it go smoothly and it could not have rolled more than two feet on the ground when I noticed the gear starting to retract. Lucky for us, the small concrete pad we take off from only rolls about 10 feet before the slope takes a severe downturn. I was holding all the up elevator I could and luckily she went airborne without so much as even scratching the APC prop. Gear was completely retracted at about a foot of altitude.
You should certainly caution anyone purchasing this timer as is they cannot monkey around on takeoff. As soon as you feel the first pull of the prop spinning up, it is time to let this baby go. The longest distance we could get that day before the wheels retracted was just short of a full lap. While I think this is perfect and just what I would like for competition, it leaves no room for tach readings or any delay once the motor starts.
The three burp warning was excellent and it could not be missed. The 5 second delay after the burps was perfect for the gear retraction and using the Schulze ESC provided the immediate brake after motor shutdown. Couldn't really give much feedback on the slow start to RPM since we don't have a long paved takeoff area.
These are the E-Flite .10 - 15 size electric retracts and they worked perfectly with a 10 amp Castle BEC and your timer.
Plan on doing some more testing, but overall I am very satisfied with this timer. If I were to make a wish list of things I would like to see integrated in future models, here are a couple of items.
If it were possible to program both the retract delay time from start-up and the speed of the actual retraction itself, those would both be positive. I am not an engineer, but it seems these could likely be controlled through the timer. Another feature I think would be nice though certainly I don't know if it is possible is the brake feature. If this function could be set through the timer, might make life easier for Castle ESC's.
Going over to Waynes' tonight to set up another plane for electric conversion - we were thinking a Castle 75 AMP ESC and another Plettenberg 25/12 (since we already have those). Will look to find a way to use a brake with this controller, but I know you said this might not be a good match. I only have one Schulze 18.61 which is in the retract ship. I could borrow this Schulze 18.61 or get another one, but wanted to get your opinion on this. Please let me know if you know of anyone else successfully using a Plettenberg with a Castle ESC.
Thanks for the great job and the quick service, you made our weekend. It was so impressive seeing that gear come up and surprisingly, we were amazed at the difference it made in this particular aircrafts performance. It is a lead sled of the highest order, probably tipping the scales at close to 80 ounces, but many of the weight related issues with cornering and wobbling seemed to smooth right out. Man, it looked good in the air as well, when I cut those four foot bottoms on the inside squares it looked like I had a mile of clearance
Thanks again and Merry Christmas !
Jim Smith (Smith Brothers Stunt) "
I am happy to relate our experiences with retracts to any who are interested. These retracts allow you to remove the coiled wire gear to replace with standard wire (without the coils) which we will do on the new Tracers we are about to build. They are very robust and I think on initial inspection and trial they will more than meet our strength needs - uses with 1/8 or 3mm wire, haven't miked yet. We all flew it a few times and Sam even got to try a nice bounced landing for a good stress test (it was very windy and cold). No problems so far. Will probably take a few photos next weekend to post here if the weather cooperates since most of us have never seen a ukie stunter flying with retracts.
Merry Christmas to all