XtremeFoamies Sentinel F3P/3D

Here lately, I've really been on a kick of building exotic and somewhat unique aircraft – quite a far cry from the types of planes that I used to fly, but an opportunity arose last Fall that I just couldn't pass up, so I'll try to document as much of this project as I possibly can.

Being in this great hobby for 28 years now, I've built and flown just about every type of airplane there is. Some of the most satisfying flying I've enjoyed, however, was that of Pattern Aerobatics. While I cannot claim to have been the “best” at this type of flying, I do have to say that it kind of brought me “out of my shell”, so to speak. If you've been in the hobby for a few years, you've no doubt found yourself in a bit of a rut as one time or another. You take off, fly the normal circuit (a left-hand pattern at my local field), do your usual “up-wind” maneuvers followed by your routine down-wind maneuvers, and then you land. About the most “out of the norm” excitement that you may experience is finding yourself having to shoot a “dead-stick” landing. For me, breaking that boring routine was getting into Pattern Aerobatics (also known simply as “Pattern”).

So what is Pattern? Basically, it's a type of flying where the pilot flies a preset sequence of maneuvers and a panel of judges score him/her in the precision and execution of those maneuvers. Without going into all of the specifics of Pattern flying here, I'll refer you to a great website article written by Mr. Bob Pastorello.

What Is Pattern?

With all that being said, it's been some years since I've played the Pattern game, but I still like to fly some of those old maneuvers, each time trying to make them more precise, more fluid, and more perfect than the last. Unfortunately, the aircraft that I've been flying as of late really don't lend themselves to precision aerobatics (WannaBug, SuperFly, HyperFlea, MiniArrow, PBF, etc.). I am happy to report that I now have an electric plane suitable to fill that void – the XtremeFoamies Sentinel!

The Sentinel is classified as a 3D aircraft which basically means that it can be an indoor Pattern aircraft, as well as a plane capable of the the type of 3D flying that many talented pilots are doing today. Let me take a moment to make one thing crystal clear – I am no 3D pilot! Oh, don't get me wrong. I would love to be among the ranks of those that can do this kind of intense, radical, and breathtaking flying, but I lack those skills (and discipline to develop them). LOL I am quite happy just being a simple Pattern Pilot.

My good friend and fellow PhlatPrinter owner, Mr. John Carver, opened a great little online store (please see the link at the end of this article) last Fall so that he could supplement his hobby by selling a line of kits that he's personally designed. The first kit in what will surely be a sizable line of great products was the Sentinel. After expressing an interest in building one of these planes to satisfy my Pattern itch, John offered to send me one to try out. My first “official” review!

In advance of the shipment of the kit, John emailed me a package containing some instructions and build photos to guide me on my way. After a close review of the photos, all I was thinking was “oh dear, what have a got myself into!”. Why? Prior to this build, I had built exactly three other airplanes comprised soley of 3mm Depron. After each of those builds I promised myself NEVER AGAIN! LOL Planes built from this thin material tend to be VERY fragile and extremely difficult for my big old hands to assemble. Additionally, I noticed from the photos that John sent that there was some sort of unusual trussing method used to strengthen the light-weight airframe and it was a method I was completely unfamiliar with. I guess it goes without saying that my excitement in embarking on this new project turned to a bit of dread. Without a doubt, I would be venturing out of my comfort zone to tread some unknown waters with this build!

After putting the build off for a few weeks, I decided that the time was finally right to start this adventure. I opened up the box and started pulling out the pieces and parts. First off I'd like to say that, as a part-time supplier of kits I've designed and cut on MY Phlatprinter, I know the challenges one can face in getting a kit to it's final destination void of shipping damage. Although there was evidence that my box had taken some pretty good hits on it's journey to me (slammed in the truck's door, flung across the shipping dock, perhaps even mistakenly delivered to a gorilla at some zoo), the parcel was so well packaged that no damage to it's contents could be detected. What I found when I removed everything was nine pieces of precisely cut 3mm Depron and a pretty extensive carbon and hardware package!

I'll warn you now, these pictures are all very large. I did this so that when you click on the thumbnail, you can see a LOT of detail...

GETTING STARTED

As I mentioned before. This plane builds using methods I've not tried in the past. Fortunately, the clearly written instructions and included pictures really guided me through the build sequences quite nicely. The key to this deign is that you build everything upside-down! The fuselage top is one of the last parts that gets glued into place. Something that you'll want to have at your disposal is a building surface that is nice and flat, and large enough to accommodate most of the wingspan and the entire length of the fuselage (I build on a piece of tempered glass).

Your first task is to join the horizontal stabilizer/elevator, fuselage side strengthener, wing, and fuse side nose pieces together. I used Bob Smith Industries Foam-Safe THIN CA, as it cures quickly when you hit it with a spray of Accelerator (also from Bob Smith Industries) and doesn't melt the foam. After these pieces have been glued, the next step is to glue the bottom fuselage piece into place. Lining it up is very easily done as John uses tabs and slots to correctly align the pieces. Be sure to use a square when putting this piece in place! Correctly squared assemblies provide for the greatest strength, which is very important in lightweight designs like this.

Something worth noting with this kit (and I don't think my pictures really describe it well) is that the hinges for the ailerons and elevator are step-cut into the foam with the PhlatPrinter's bit. All the builder has to do here is simply strengthen the hinge-point with a strip of lightweight clear tape across the top of the wing/aileron area, and then flex the surface up and down a bit to loosen it up – a truly unique and ingenious hinging method!

TRUSSING FOR STRENGTH

This is, perhaps, the biggest concern I had with the build – the trussing. As it turned out, it was all a piece of cake. If you follow the instructions and carefully cut the carbon fiber rods to the exact lengths noted in the instructions, you just can not go wrong. Rather than trying to explain how everything goes together, I'll just let the pictures speak their “thousand words” each. Again, I cannot stress enough just how easy this technique turned out to be. It was so easy, in fact, that I fully intend to incorporate this design in some future planes that I've been working on (thanks, John!).

And, as you can see, I couldn't resist mocking up the plane by temporary affixing the rudder and top fuselage piece in place – looks cool, eh?

ELECTRONICS INSTALLATION

Here is one of the things that I (as a total perfectionist) really hate doing – installing all of the electronics. I am so fussy about getting everything positioned just right that I tend to second-guess everything to the “nth” degree. You see, the goal with any GOOD radio installation is to have everything installed in such a way that you can achieve perfect balance of the model (Center Of Gravity) without the battery installed. Doing it this way ensures that when you install the battery directly on the CG, the plane will always balance – no matter what size battery pack you use (this is an old trick I learned long ago with Nitro-powered aircraft – nothing worse than re-trimming a plane in flight when the fuel tank drains!). I don't balance my models with the battery – I balance them up front with the radio equipment. With this kit, the servos cut-outs are already done, so you've got that part all worked out for you! Everything else just kind of fell into place, so rather than go into in real detail with this boring stuff, I'll just inundate you with a bunch of pictures. LOL

THE GEAR I USED

I had intended to use a LazerToyz 17 gram outrunner (2211-17) on this model with a small 2s pack, but my new motor was DOA. Not wanting to wait any longer to get this little plane in the air, I opted to just use my Blue Wonder 1500kv motor with my 2s350 FlightPower battery and a GWS 8060 Slow propellor. The ESC is a Castle Creations Thunderbird 9. As you probably ascertained from the pictures above, I am using a Spektrum AR6300 receiver and three of the 6 gram DSP60J servos. I originally reported on my podcast that this combination yielded a 6.6 oz plane, but I reported that erroneously. I forgot to subtract the fixture (a cut-away plastic coffee cup) I used to help me balance this model on my scale. My actual weight was 6.1 ounces! That is not bad for an aircraft of this size (36 inch Wingspan, 38” Length). Had I been able to save weight using that 17 gram outrunner instead of the Blue Wonder, I should have been able to get under that 6 ounce mark!

DECORATION

Again, I was in such a hurry to get this plane finished off that I elected to not airbrush it. Left with a drab old all-white plane, I had to do something with it so I opted to try out something that I learned from Mark and Trish Carew (aka, the PhlatBoyZ). I worked up some graphics in Adobe Illustrator CS and printed them out on Avery #8665 label stock. This stuff is clear with an inkjet matte finish, sticks well, and holds the inks nicely. Below are some pics showing my final aircraft.

FLIGHT PERFORMANCE

As I mentioned earlier, I am no 3D pilot so once I settled into flying this plane in a manner that is most comfortable for me (Pattern), I quickly became one with it. It's every bit as smooth as the 1.20-sized plane I used to fly, but this one flies so much slower! I think it really makes me look much better a pilot than I really am. LOL Down-lines are slow due to the canter on the side-force generators on the wings, knife-edges are almost automatic (partially due to that aft CG I like to use – about 40% of the average wing-chord), inverted flight requires only the slightest hint of down elevator, and snaps are VERY crisp!

As of the writing of this article, I only have about three flights on this new plane, but I can see that it's a real winner! I have been forced to fly outdoors only with it as I have been unable to make an indoor flying session yet this year! I am hoping to get some gym-time in at least once before the season is over so that I can enjoy it in "dead air" as well as put it in the hands of my buddy (a REAL 3D pilot). At that point I should be able to get some good video to post here of the Sentinel properly put through it's paces.

FINAL THOUGHTS

If you, like me, have been looking for an indoor Pattern or 3D plane to hone your skills on I must recommend the XtremeFoamies Sentinel. The aircraft builds quickly without any surprises, is of the utmost quality, flies wonderfully, and is a true bargain at the price that's advertised. Snag one up; I don't think you'll be disappointed!

www.XtremeFoamies.com