hello room,

I am thinking about getting this plane, Just wondering who has .61 2 strokes or larger in it.

For those of you who are interested in more info about balancing this plane, here are my two cents. I installed an OS 46 fx with futaba 3004 servos in the stock locations (ie two elevator servos and rudder servos mounted in the rear). Mine came out way tail heavy. I ended up mounting the 600 mah receiver battery and 3 additional ounces of lead underneath the fuel tank to get it to balance.

I haven't gotten to fly this plane yet, but it sure looks great. Covering is great, parts fit is very good.

There isn't area in the cowl for cooling air to exit. Has anyone had problems with overheating?

You will have to cut out some of the bottom of the cowl to allow air to exit.

Bob

The rocket is a great looking plane but when in the air there is to many white arears both top and bottom and you quickly loose orientation. I bought it because it looked fast, but it is tail heavy with 3 servos in the tail , I would put them in the fuselarge if poss. I fitted an Irvine 53 2 stroke in mine, on its side with the exhaust neatly cut in the bottom. I did have to shorten it and remove the baffles or it would not exit the cowl, this made it sound a bit more raw, had an 11x7 pulled it great until the elevator hinges pulled out and nose dived into the beach, make sure you use a realy thin CA or those hinges WILL PULL OUT. Good luck

I maidened my Harmon Rocket this morning. I was careful to place CG about 5/8 inch ahead of the range recommended in the instructions, since 3 servos are mounted on the tail, and due to posts I read on these threads regarding balancing the plane.
I motored it with an Evo .46/Bisson Pitts muffler and 11x6 APC prop. Plenty of oompf, good handling with low rates despite 10-20mph wind and gusts that occasionally hit 25-30 at altitude with turbulence from a tree line upwind of field.
Tomorrow, larger diameter wheels, 12x6 prop and hopefully, less wind.
By the way, this was my first ARF. My two previous planes have all been RTF trainers.

stallwart ,
So, can u tell us more about how it flew and what u thought about it ?
Thanks.
Jake.

Since it was my first ARF, I was somewhat trepidated about flying the maiden myself. An AMAC contender in our club was onhand and checked my work. I had hoped he would maiden the plane, but time taken figuring out some radio issues prevented him from being available. I had to do it myself[X(]

First, I would not recommend using the supplied z-bend connection to the throttle. The metal to metal connection seemed to cause interference problems. I know this is "Ned's First Reader" stuff, but it was so easy to use the kit supplied rod. As long as no one else was using their radio, it didn't seem to matter, but I have changed throttle linkage this afternoon. I used 2-56 rods for every thing else.

As for flight, I was amazed! I had purposely balanced with the CG a bit forward for safety and still found the need for a couple of clicks of down on the vator. Surprisingly, about 4 clicks of right aileron trim was needed, despite my inability to get a good axial balance and with the torque effect of the prop. Once trimmed, it flew very well and very predictably. Nothing it did in horizontal or vertical maneouvers caused any surprises. Landing (6 or 7 flights) never caused me to bend the gear struts, which I was somewhat concerned about due to reports on the threads. Landings need very little power, less than I expected, even accounting for the stiff headwind this morning. Please keep in mind I've only flown an H-9 Arrow, Alpha and PTS P-51 before this plane and am quite green.

All flights were at low rates, with travel set at recommended throws. The radio I used is the limited JR 421 which doesn't give me an easy way to change from hi to lo rates (still new at this).

The quick answer is the plane flies great. The peanut gallery were all impressed, and believe me, I'm not that good an R/C pilot.

If you paint the inside of your canopy black it not only looks cool but helps with orientation as well.

If you're looking for more paint and trim schemes for the HR3, look around on this site.

http://www.harmonrocket.com/main.htm

Some photos of mine. Flew again today with terrific winds. I made some mods (prop, larger wheels for our rough field, changed throttle linkage, and some other minor adjustments) that threw trim way off and faced near disaster. Got some help from clubmates and manged another 5 or 6 flights.

The plane definitely dislikes strong wind. It has a tendency to weathervane with the large vertical tail surfaces. However, rolls were crisp and axial with little or no rudder or elevator input needed. Even with such a small engine as the Evo .46, it looped easily from level flight. With low rates it is still very sensitive to input. With the wind so high, it was difficult to test stall characteristics properly.

It’s been a bad week for flying. Firstly I put my OMP katana profile in, (pilot error). Then two days later my trusty workhorse Seagull Harmon Rocket suffered terminal tail plane flutter after performing some split S`s and went it very fast with complete lack of elevator control.
The tail plane has snapped in half on either side of the stab. The only thing holding it together is the elevators. Worst of all the battery broke free on contact, striped the wire and shorted out, frying all the electrics. The lesson here being don’t cable tie the battery lead to tidy it up.
The plane only had an Irvine 46 so was not exactly over powered, in fact I was considering a bigger engine for it. I had joined the two elevators together with 3mm rod, running from one s3001. I had used the supplied pushrods which at the time seemed sturdy enough. I had even filmed the hinge gaps as I do with all my models.

This was a fantastic model. It is brilliant value for money at around £90 and easily the best quality of finish and least amount of construction from any ARTF I have ever built. But I know someone else in this thread had exactly the same failure so be warned.

With hind sight I would have strengthened the tail plane, maybe braced it. I would have also used better pushrods and maybe a better servo.
The plane is in remarkably good shape considering the speed at which it hit the ground. I won’t bother repairing it; I might as well just buy another at £90.
I would still recommend this plane to all from novice to experienced pilots. It makes a great windy day bash plane.
BTW the Cof G is spot on with the Irvine 46 up front and only two standard servos in the tail. Battery was on the servo tray.
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Sorry about your losses, but I'm sure it'll all soon be forgotten with a #90 outlay and a few hours work. I have also considered bracing the tail feathers, but there's not that much to tie on to back there.
Meanwhile, mine's flying better and better, or maybe I'm becoming better with it.

I maidened my son's HR the other day and shortly after takeoff, while flying full-bore, but straight and level, I had one side of the stab fail. Fortunately I was able to bring it in safely.

We added bracing to the tail after it was glued back in place. He also changed to 4-40 pushrods

I must have managed to get one with a stronger tail section. After 40 odd flights, everything's still fine.....except, after sitting in the sun on the flight line, the warp on the port horiz. stab. reappears. 3 clicks of right aileron trim seems to take care of that.

anyone have more flight reports for this bird..im considering getting one for a sunday flyer/semi speed plane...ive seen where some members have had failures mostly to the stab..this concerns me..as saftey is most important when wanting speed..thanks guys


chris

I have a HR thats been sitting around the shop. After reading this post I can't decide which power plant to use..a new Saito .65 or the Evo.46? probable will boil down to which is easier to install, any thoughts or suggestions would be welcome. I get the feeling that I would have to beef-up the LG and use a pull-pull if I go with the Saito?. Also are the twin elevator servos necessary or can I just rod them together? Thanks. Mikel-T

I got 2 flights in on mine today its got an evo .46 and its fairly quick.I'm still using the stock gear its fine if you grease every landing .I've bent it up a few times but it bent right back.Fun little plane though I'm glad I picked it up

Hello Evrybody
French Guy flying an Harmon Rocket, with an OS 70 SURPASS II...incredible filght performances (with APC 13X7)
The landing gear has been reinforced with crossed cables, in order to optimize the ****ty one provided.
I can promise that the performances are huge, and the OS fits perfectly with the plane

Mikel-T, we rodded the two elevators together, (1/8" Music wire) but if you do that, beef up the pushrod.

Personally, I think the pushrods are too flimsy even if you're using two servos.

And after hearing all of the Stab problems that others have had, (And having one myself) I would recommend bracing the Stab.

how did you brace the stab? will a carbon rod set up like on the funtana .90 work?I like to dive bomb the runway and I'd hate to auger it in wide open

I did it on top, but you could easily do it on bottom like the Funtana

thank you Minnflyer, your setup is much better . I'm gonna reproduce your setup for my planes that looks really stout !

We flew it yesterday for the first time with the new tail brace and it worked great. Did lots of VERY high-speed passes without any problems.

I am just starting to build my new Harmon Rocket. I am VERY concerned about the weak horizontal stab. I am going to install my new Jett 50 in the nose, and I really want to run it FAST... [>:] So I am thinking about removing the covering from the bottom of the stab and adding new balsa structure near the center section in attempt to make it much stronger. I would rather not add and external wires if I can help it. Has anyone attempted this? Any opinions on wether or not this might do the trick? The Rocket looks like a great kit, can't wait to fly it. Thanks to all for your suggestions!

Jeff

Jeff,

I am flying with an OS .61 FX and a 12x7 prop. I did nothing to strengthen the horizontal stabilizer, and have had no problems in about 20 flights. I like to fly it hard and fast, and the stabilizer is still very firm, with no sign of weakening. I would think if you add some balsa to the bottom of the stabilizer right at the root, or maybe some triangle stock to give you extra surface area to glue to the side of the fuse, this would be good insurance. I would think that the stabilizer bar would be easier.



Minnflyer,
Speaking of the stabilizer bar. What did you use for that. It looks very nice and clean. Did you make yours or is there a prebuilt one you can buy? I wouldn't mind the extra support just in case.

Thanks,

Adam

Those are just electrical ring connectors soldered to a piece of pushrod wire