After removal of the foam, the servo will fit into the opening with the mounting tabs flush against the foam.
A HET 6904 fan is a perfect fit with the mounting lugs removed. I'm using a HET 3W motor and TS36 ESC to run on a 2200 ma 4s Dualsky lipo pack for this project.
1/64" ply sheeting is added to the top and bottom of the fuselage for extra strength on the taileron supports. Apply it to the tops 1st since it's a straight surface.
After the 5 minute epoxy cures on the tops, the lower sheeting is added.
In stock form the taileron swivel bushings tend to loosen up after a few flights So, I went ahead and fixed them in advance on this one. They can be popped out fairly easy since they appear to only be glued to the plastic outer covers.
Before gluing them back in, I push the small ends of the bushings into some wax to fill the hole in the bushing. Apply epoxy liberally inside the holes in the foam and to the outside of the bushing. After pushing the bushing back into place and before the epoxy cures, use a small piece of wire to push the wax (and any epoxy) back out of the bushing.
In stock form the clear plastic taileron "covers" play an important role in strengthening the taileron supports. On this one they are mostly for appearance since the ply is much stronger than stock form with the plastic. They will be painted white along with the ply before finishing the model.
Just as a note for anyone else contemplating this experiment, the leading edge of the fan housing is located about 1/4" back from the point used for measuring stock fan location.
A shot down the inlet to the fan with the lower ducting installed.The plans call for just a few dabs of epoxy down each side, but in this case I made the glue joint the full length. In the event the airframe outlives the power plant, I'll worry about cutting access holes at that time.Let's not forget, this is my 4th one of these. <g>
One of my dislikes in the stock kit is the vertical fin since it's bare foam. I don't know why they don't give it the same wrap that's on the wing and tailerons. Seems like I'm constantly "dinging" mine. On this build I glassed the entire vertical
using light cloth and minwax poly-acrylic. I also added a glass joint where the wings join to the fuselage since I'm not using the included decals.
Almost completed. I still have to add "my fix" to the canopy attachment and balance it when the battery pack arrives. All my past ones have used the stock color scheme (decals) but wanted this one to resemble the big Cermark 16 I'm building in Edwards Air base colors.
My canopy latch modification is pretty simple and only requires the sacrifice of a clicker type ink pen to make. The factory slot is enlarged to accomodate the size of the spring after which it's secured into place with some 5 minute epoxy. CAUTION: The epoxy only encloses about 1/3 of the total spring length. Much more than that and you could wind up with a pin that will not retract far enough.
Stocker & modified side by side.
Photo taken night before.
Took both to work with me today for a precise weigh in on some good scales.
AUW stock with Dualsky 2200 3s 25c = 20.8 oz.
Thrust stock 14.5 oz.
AUW mod with Dualsky 2200 4s 25c = 26.6 oz.
Thrust mod: 27 oz + (not measured since the esc popped when I went to run it up. grrrr!).
CG balance worked out (1/4" back from cheater hole leading edge) with the Dualsky 2200 4s 25c pack mounted as shown here. It's close but the canopy does still fit without any modifications.
I don't yet know the AUW of this one, but do know that thrust to weight ratio exceeds 1:1 at full throttle. It would be capable of climbing straight up from a dead stop if there was enough airflow over the control surfaces to control it.
It can be done, in one evening even if your determined to get a test flight the next day. Stopped by Georges and picked up a Castle Phoenix 60 on my way home from work. After getting home cut the belly open. Having a hot knife made it fairly easy to get a reasonably clean cut in the foam.
New esc installed (yes, I had to solder all the connectors) and fuselage prepped for reinstalling the belly pan. I used some thin strips of 1/64" ply to reinforce the portions of the inlet ahead of the fan as well as at the front & rear for the belly to rest on.
Repair completed. I may still add some glass to the seam but hate to keep adding weight. For now a little clear packing tape does the trick. Using the Castle meant having to add a BEC. (Luckily I had one of the little Castle lightweights) I could have bought 2 TS-54's for what this fix cost. But, determination over rode frugality. ;-)
At least it still makes enough thrust to overcome it's own weight and is ready for a test flight tomorrow morning.
A "Family Portrait". Big brother, little brother and the kid from down the street.
The maiden test flight could have gone better, but at least it went (on the second attempt).
I really wanted both hands on the radio when it launched so asked another club member to toss it for me. Somehow he got a finger caught in the cheater hole and it rolled the plane into the ground as soon as it left his hand. Broke the nose off pretty much even with the front of the inlet. It was a pretty clean break and I managed to borrow some 5 minute epoxy from another club member and glued it back on. (I was really DETERMINED!)
I did the launch myself the second time and luckily it wasn't far from being trimmed. Took about 4 clicks of down and another couple of left to have it where I wanted it.
It's not as fast as I thought it would be and I'm guessing around 105-110 mph at full throttle but has outstanding vertical performance. It flies about as fast at half throttle as the stocker does at full and a 4 minute flight left the 2200 ma 4s pack about 110 degrees when I landed it. My charger just finished putting 1382 ma back in it. Not too shabby in my book. I usually burn that much in the stocker for a five minute flight and land with the batteries hotter than that 'cause I'm pushing them harder.
It's kind of hard to see the little speck of an airplane at times but my camera man draftee did a pretty good job of keeping up with a fast moving small target. With that said, press the play button if you want to see the video.