http://www.rcuniverse.com/forum/atta...mentid=2047358Thanks for the comments Mike. the problem with the servo mounts is not the length of the servo fit but the width . The servo cover legs ( if you want to call it that) are not long enough for the 20mm wide servos and the outer hole sits pretty close to the outer end of the servo cover mount legs. Sorry , Maybe I didn't explain it good enough. Thanks

Here is a picture of what I mean. I use .75mm spacer between servo and the cover si when I mount the rubber anti-vibration mounts I have room. don't like the servo touching anything solid......

I love my Sprint. As a first jet, it is the way to go.It flies nicely and will do acrobatics as well. Lands almost by itself!

You are very lucky to get one. However, there are a lot of tips in the thread here. I got mine last winter and all the little problems listed here years ago still applied. So, ... I suggest making a abbreviated list of the problems and fixes listed before you build it.

I never used crow. 1/2 Flap to slow her down and full flap for landing. Just chop the throttle on the base leg and let it glide in. If you get into a significant cross wind, then I keep the throttle up a bit. I do have a long asphalt runway here. So I usually touch down right in front of me. This thing has a wide range of speed at which you can land it.

The problem I had with the pro-link gear were the holes for the axles were not drilled thru and the hole seems to be drilled in the wrong side putting the axle on the wrong side. Lot of people ran into that. I just drilled the axle hole thru and then cut the axles to length to fill the hole completely. However, later I discovered that if you remove the links you can swap them and solve the problem w/o drilling.

On the brakes I went with air. The Air system control valve that Dreamworks provided did not work very well proportionally. I ended up trashing that electronic valve and going over to the U.P. 6. Good luck with the Electric brakes. They may work just fine. I considered swapping over to them. But after getting the U.P.6, I stuck with the air.

Boomer Sprint
 

Yes I was very very lucky to get a new in the box one. Picked up the last one from Kilroy's building service. Not sure what the going rate was when you bought yours but ; hey I guess when you get the last one in NA can't be too choosy ! I think I will forget the idea of Crow on the rudders as is not needed by what I have read. I will be making a mold copy of the wheel wells as well and making up fibreglass ones as well as I don't care for the bolt down fit I have seen in some of the pictures. When I get to that stage will see where I am at.

What's was your impression on the servo cover legs I posted ..... not much there for the outer screws ?

Thanks

My covers have held up to over 100 flights. I used Hitec 5585MH all around. I pre-drilled all the mounting holes in the covers. Your servo does not look like it is flush with the cover. What is keeping it out there? I do not recall my fit being that close to the edge of the mount. I did have to make sure the servos were centered and flush with the covers though.

By the way: I trashed all the provided hardware. Went to Standard screws and bolts. Trashed the Links and clevises. I ended up using Dubro horns and clevises. Made up some linkages using threaded rod covered with carbon fiber tube. I have seen several out there with bent control linkage. Most of the ones I have seen that have been out there in the field for a while have replaced linkage and control horns.

As per one of my earlier posts I use .75mm spacing between the cover and the servo as I don't care for the flush fit plus it doesn't make much difference in any case. I have some ideas that will probably work. I agree with you on the hardware and I hate the way they put Z bends in the control rods. Z bends are fine for 40 size and smaller planes of foamies but definitely not Jets.

I agree, rudder brakes are not necessary, lands like a ***** cat. I don't use crow either, those thick wings slow it down nicely, but not a bad thing to have as an option. I have a K100 in mine.
Cant help on the brakes.
Chris

I have seen a lot of experienced jet pilots who hard mount their servos to the bearers, no grommets or inserts just large headed screws, they say the grommets where designed for IC applications with lots of vibration, this does not apply with turbines, it seems that the more experience you have the less complicated you make your everyday jets, Ali Mc used Z bends and all the standard hardware, even Spektrum servos, think they where the 921's on his Sprints.

You guys with your long runways and landing half a mile away have it all your own way, I can see both ends of our grass patch even if I am lying down, this makes crow a necessity, its nice to have if you need it, forgot to mention that all of the crow is set against the throttle, if I have to open up to go around the ailerons go back to centre and the flaps go to half setting, again only really necessary if you have a short runway.

Mike

This thread got me thinking of how many flights Ive had on mine with my servos hard mounted to the plastic servo mounts. It reminded me of a video my friend made FIVE years ago. Ive got hundreds if flights on this plane now.

For your entertainment :)
http://vimeo.com/6446884

Such a pitty they not available anymore, love my Sprint.

NEXT question.... Has anyone used the Dubro HD swivel link with 4-40 connecting wire rods... any pros cons and opinions please . Have used them on larger aircraft but not jets before as this is my first one. Haven't read a whole lot on linkages but then I am only at page 74. Thanks

Used Dubro horns and clevises. Made linkage out of 4 x 40 threaded rod and covered with carbon fiber tubing to dress things up. Just went over all the linkage today. I did find a cotter pin that was missing from the Dubro hardware. Used Hitec high voltage, metal geared digital servos all around. Used Hitec's servo arms. They put their HD arms in the HD servos. The guys at Aeroworks claim they never seen or heard of one of those plastic arms fail. Typically, I have in the past stuck to aluminum arms. But this one has the stock arms.

Nice video. Sitting here looking out the window at 4" on new snow! Although, one of our jet guys just sent me an email suggesting skis. Not sure how I would get them to retract, without a lot of work. :)

Im using the Dubro HD swivel link aswell. There still working after years. Though I think I did change the one on the elevator once. Gets kinda hot back there and I didnt like the look of it. But that was after 3-4 years of flying. What ever you use..Keep an eye on the elevator linkage. Many of us use a pipe to direct the more lazy heat/exhaust beyond the Horizontal stab during start up. I have also laminated an area under the Hor Stab with alluminum duct tape since the heat can hit that area during very slow flight, hovering etc..

Thanks on the vid Len... And I too am looking at 2" of snow this morn :(

Hi Sejenssen ;

just wondering how how you made out with your VT80 turbine as far as the balance , did you require any balancing lead up front and
how much. I am also considering the VT80. Due it's lower weight . Also do you have some pictures of where you mounted it, and the rest of the fuse installation ......Many thanks .
Len
From the sunny Okanagan , cold but no snow yet !

http://www.rcuniverse.com/forum/atta...mentid=2053217http://www.rcuniverse.com/forum/atta...mentid=2053218http://www.rcuniverse.com/forum/atta...mentid=2053219Starting to do my servo install and find that the servo cover legs vary in length of about 17.6mm to 17.9mm. Have contacted a few with older sprints
and find they are 20mm long. More like what I need. The first pic is an ealier servo cover with a 20mm wide Futaba servo and the second is measured and the third is my Sanwa servo 19.5mm wide mounted flush with the cover... no space. Have checked with Boomerang and hope to get replacements except for the rudders as using much narrow servos there.

Having the servo covers problem fixed by Boomerang jets for the ones I need. I only ask for what I need ....no more, no less. Thanks Boomerang for coming through. In the process of re gluing most of the ply fittings . Has anyone flown the Sprint without gluing the fuse to the centre wing section as recommended by Alan ;as I am contemplating glass thus section at some point as many have done. Would like some feedback, please. Thanks

I recall reading way back in this thread that someone asked the same question about not gluing the wing/fuse section. Alan replied that it was very important that the wing be glued to the fuse.


Thats all I can tell you.

http://www.rcuniverse.com/forum/atta...mentid=2069165http://www.rcuniverse.com/forum/atta...mentid=2069166Yes, I do recall reading that but also a couple had not done the full glue and did not have a problem except they did not really do a full out flying extreme flying with it..

My reasoning for leaving it as a bolt on is I want to glass the center section before permanently doing a glue job... Sooo I may just do the center glassing and then paint in the spring. Will see.

Received some replacement servo covers with longer mounts and should do just fine. Gotta get at it this week.

Here are a couple of changes I did and yes, the brakes fit much better when drilled thru and mounted on the other side. The other picture is a mode I will be doing with the main CF wing tube. I made some inner CF tubes that will be glued inside the thin CF main wing tube and tie in thru from the inner wing section into the outer plug in wings. I am sure the wing tube is fine but feel more comfortable with a beefed up supported section, tying in the three pieces. Each piece is just under 5 inches by 1mm wall thickness .

FINALLY, have decided to glass the centre section since it is highly recommended to be glued to the fuse rather than do it later. Since the wood is very soft to keep control of the weight I find hat every time I look at it there seems to be compression marks. The JM VT80 should be here early next week.

If there are any suggestions on the build , comments are welcomed.

I initially drilled the holes in the link all the way through for the axles and then swapped the struts around. This got the Prolink brakes to fit fully on the machined boss of the strut. However, later, when replacing link springs, I figured it out that all I really needed to do was swap the trailing links and then the holes were on the right side of the strut to allow full engagement of the brake on the strut's boss. Either way works.

I just glued mine per the manual. Have never seen any compression marks or any other signs of deterioration and, ... I have a P-90RXi (24# + thrust) and put the plane through some pretty extreme acrobatics. No need to glass the thing, unless you just want to do it for the heck of it.

To Len from Len:
Regarding the axles and brake lineup ; Yes I thought of the same thing but was easier to drill than disturb all the Loctited screws. Not a problem, mine`s done as per posting. I used a brass pipe to line the main gear up. some have used a solid 3-16 rod I think.

My center wood may have been softer , so decided to do the glassing. actually I found the wood in the center section to be very soft for an aircraft like this. Don`t care for the extra work but probably better in the end. Wonder who will be handling the Boomerang line in the US ; in future.

Found a great fix for the aluminum guide rods and tight fit. Had a round file in my tools that was exactly the same diameter as
the aluminum rods. Chucked that in my variable speed drill and run it into the holes very gently and now everything slides perfectly. My guess is that when they drilled and taped the lock screws holes for the wing rods is that some of the metal stuck down into the wing rod holes creating binding with the rods.

Am into my second reading of this forum and I know I read how many drops of thin CA on each fibre hinge but for the life of me forgot how many. Should have copied it into my manual when I read it first time. Too much to remember ... Lol ...tried a search but came up empty handed . Thanks for th help. Did 10 drop each side per hinge so far. This enough ?

Another issue , small but still an issue is the top hatch trim matching the canopy. When slid forward to match the front then the back of the canopy does not fit the back and when slid back to match at the rear then colour mismatch at the front. More unplanned work that should not be there on this price of an ARF.

Pulled the covering off the big top hatch and glassed it. Primed and waiting for some decent weather so I can paint. Will post pictures when done. Anybody know when and if any dealership being set up in North America again or what the status is with Boomerang jets ?

Colin the UK Boomerang importer has stated a couple of months ago thats he intends to bring the kits back to the usa at some point in the future but did not have a target date.
I suspect we wont hear anything until all is set up and ready to go.