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RadJet 800 from Hobby King

#3
i just ordered mine, it looks very similiar to that of a Bill Evans glow model from the 70's..google "Bill Evans Leading Edge .40 size" its a very nice plane as well
 
#4
I purchased it as the ARF. I would do it this way again as it allows versatility with the hatch covers. I understand the PNP version has all of this glued in place. I also installed a 6mm spar when I glued the wings to the fuselage. I love this plane and bring it almost every time we fly. Make sure you get the CG right. With a 1300 battery I had to add about 50g of weight back by the motor. My son clocked me at 119mph with that Doppler app for his phone with a 4s. Not sure how accurate it is but the plane can keep up with my sons Stryker.
 
#5
so im guessin that the top speed is close to 119? does any one know how stable it will be at maybe half or 3/4 throttle? it might be too much for me right off the bat.
 
#6
so im guessin that the top speed is close to 119? does any one know how stable it will be at maybe half or 3/4 throttle? it might be too much for me right off the bat.
119 was on the 4s. It's right at 100 on the 3s. I rarely use the 4s because its really too much for the stock motor. When I fly with the 3s I am between half and three quarter throttle most of the time.
 

lobstermash

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#9
OK, just finished putting together the PNF version. Unlike many planes I've built recently, this one requires more than just hot glue thanks to the plastic canopy, skid plate and servo covers (I've tried this with hot glue before on other planes and the plastic wilts). I'm also having issues with the canopy space - the 1300 fits nicely, but the cables and XT60 connector don't want to pack down properly. Other than that I'm liking the quality of the foam and simplicity, though not rapidity, of the build.

I'm surprised at the quoted wing loading, which isn't that far above a Bixler, so there should be some good slow flying characteristics. I notice that the motor is now different to the Bixler motor too - something that's changed from the early build. I wish I could get into the guts to check out the ESC and motor mount, but they're firmly glued down with what looks to be way too much glue. It'll be a delicate surgical procedure if/when I need to swap the motor out (I've got an AXN motor begging to go in something fast).

Looking forward to the maiden.
 

Brian fred carr

Site Moderator
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#10
Well chaps this how they fly...and what i did to mine to make it portable....keep flying and an intro to where it was flown.....the plane is well worth $49.00 i am about to chuck a 2200kv on her and see what she does all the footage was flown on stock with a 1000Mah 3s
 
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lobstermash

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#11
Took her up for a maiden today. Andre, you're going to love it! The only sticking point is the launch. I sidearm launch my deltas, and this is every bit as tricky as the Parkjet to get in the air. On my first attempt, I accidentally bumped the throttle (I fly mode 1) and couldn't get it going again quick enough. Got a bump on the nose for my trouble.

Next attempt I almost lost it again, but managed to recover. Once it gets going, it's a point and shoot, wonderful little plane to fly. I'd just flown my Parkjet, and in comparison this is noticeably slower with the stock motor. Unlike the Parkjet, which had unlimited vertical with both the stock motor and my EDF, it runs out of puff after a few meters unless you build up some speed for vertical climbs. Speaking of vertical though, the ailerons have full command right up to stall. Now that's an impressive attribute.

The speed run is respectable - I'd have a guess about 75-80mph. With pretty high throttle most of the time, I drained the 1300 3s pack in about 6 minutes. Although it glides OK, I found for landing it goes better coming in fast and low, using ground effect to get the angle of attack right. One flare gets it to landing speed, the second flare stops it from nosing in.

As far as balance goes, the 1300 probably puts it slightly nose heavy, but I only needed a couple of clicks of trim to keep the nose level at half throttle. I did used to think that the Parkjet was the one plane that everyone should have, being cheap, fast and fun, but this ticks the boxes and is a lot higher quality, reliable and better value (to get the Parkjet flying costs about the same).
 

lobstermash

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#13
Er, um, yeah... Fell from about 7-8 meters when it went into a flat spin. I couldn't pull out, but it only had a small bump on its nose. Next I botched a landing with the throws perhaps a little too high, which produced a cartwheel. Again, a little bump on the nose and a missing low battery alarm, and that's it!
 

lobstermash

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#15
Er, in a word, no. The Funjet is bigger, so is more suited to crazy 5s and 6s setups. I reckon you could put a pretty respectable 4s system in the Radjet and some carbon in the wings to handle the extra G. But space is fairly tight in the fuse. And I'm not sure if it would reach 350km/h like some of the Funjet setups I've seen (glydr, did you ever see that guy's 6s one at Kambah? It was a frightening machine... I wonder where he flies it now).
 

jholber2

Junior Member
#16
Maiden flight of my Radjet 800 yesterday was really dissappointing. Maybe I received a defective motor?

Well maybe I was a little impressed / and a little dissappointed. Build time was pretty quick. In the time it took me to charge 2 new Zippy 1300's, all of the epoxy was set and controls were setup. I waited til the next afternoon to fly and the plane really felt solid without any spars in the wings. The EPO foam in this kit is quite dense and has a sturdy feel to it. The motor felt like it made good thrust.

My biggest concern is the CG. To get the CG that the manual listed...I had to mount the receiver in the mid portion of the plane, and the battery almost halfway into the midsection. With it pushed to the back of the canopy, it was way too nose heavy. Even halfway in, it was still a little nose heavy but I figured I could trim it out...

Wrong! 3/4 power take off, it fell like a brick. I got my girlfriend to toss it on the next go...full throttle...barely creeped off and I was about to put it down but it picked speed after 20 yards and started to climb. I expected it to rocket off, but it just kept creeping. Turned it into the wind to get some lift and I knew it was going down. It started blowing backwards in a 7 mph breeze! Tried to turn it around but it dropped in a spiral. Dropped it hard from about 40 feet. Crushed my receiver, split my lipo, broke the motor shaft off.

The plane is in perfect shape! A little wrinkled on the nose but not chipped, bent or broken! I'm not sure what to say about this little plane. It might be great as a kit with your own motor, esc...but the stock motor/esc was a joke if not defective. The motor looks high quality, maybe just over-rated for this setup?

Anyone know of a replacement shaft for this 1850kv motor? I would like to bench it to see what it is really pushing...
 
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lobstermash

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#17
A lot of advice on rcg is that the cg is more like 400mm from the nose. I fly mine with the cg just in front of the finger holes, which is still a little nose heavy. To get this, my 1300 has to go right into the circle hole as far as possible.

Just getting a replacement shaft would probably cost as much as a new motor. I expected the stock motor would be the Bixler motor, as both planes are made by the same manufacturer and the early Radjet pics show it being the same. But my motor has a much deeper bell. A lot of people run I think a 26-30 2200kv motor on this for extra go. I'm happy with the stock motor at the moment.

It sounds to me like you might have had the prop on backwards...
 

jholber2

Junior Member
#18
Haha, thanks for the input. I actually went to check the rotation and prop direction. It was correct. ;-) I took a stainless steel flybar from a crashed heli and made a new shaft. I used the extra prop supplied with the kit and benched the motor/ESC on my bench-type power supply.

The stock motor/esc only pulled 8 amps WOT. Swapped out the esc with an E-flite pro 35. 13 amps... There is a huge difference in mid-range rpm between to the two setups. The stock esc barely moves it at 1/4 stick.

Took it up on my f22 scratch build with a turnigy plush 40 and the same prop...it's not bad, still not a rocket, but flyable. I still think it would be over-rated for the radjet's lower wing loading.

MY ADVICE: GET THE ARF. GET A BIGGER MOTOR. (It will help with the CG as well)

*Or buy the pnf and get a pretty good deal on small motor and two servos.
 
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lobstermash

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#19
The only other thing I could think of would be if the prop isn't secured tightly enough and starts spinning on itself at higher throttle. Mine really tears along at WOT and is a bundle of fun. I wish I got the ARF (wasn't available in my local warehouse) so I could hollow out the battery hatch a little, just to bring the cg back a bit. Oh, and probably add an AXN motor (2200kv) for an extra few mph.

A few people on RCG have stuck a 4s in and the stock motor only draws 16A and gives it an extra 10-15mph or so. Not bad for a stock system, hitting the 95-100mph!