Any thoughts/tips on the Starmax JAS-39 Gripen?

[K CLOSE]

Anybody got any pointers/thoughts on the JAS-39 Gripen? I had a real bad experience with the RICCS Mirage 2000 (H/L put it right 'tho) and now I have the Starmax coming. I STILL haven't gotten around to building my GWS ME 262, but to be fair it's only been like 2 years:roll:. Anyway, I thought a RTF as a first EDF seemed a DGI (dam good idea). Any pointers anyone? I mean besides build the 262 already.:p>

[bhatch21]

Hi. I have the StarMax Gripen and I'm flying it with my own electronics. If you get the RTF version, it'll likely have the 4300kv motor and draw 25-28 amps. This is a heavy load for the stock 1300 18C pack. It will come down hot and won't last long. I'm using a 1800 20C pack pushed back in the modded battery cage. Most people are flying this one balanced about 1.5" further aft than what the manual gives for the C.G. My Gripen didn't rotate on the maiden until I chopped the throttle. After that, I turned the main landing gear around and now it rotates easily. My setup makes 300 watts and I feel it needs more power. It tracks well in the air, holds a nice harrier, and flares easily for landings. Good luck.

[K CLOSE]

bhatch21,
Thanks for the tips. So the basic airframe is good, but she's gonna be underpowered as stock. Would you suggest a R/O/G (clubs runway is long and paved) or a strong hand launch by a friend?

[bhatch21]

I wouldn't say its underpowered for a park flier EDF, but more power would make its flight performance better. Top speed with my 300 watt setup is probably 45mph. I fly off of pavement myself, and would suggest this method for the maiden. Be prepared for a 100-150' run out.

[Angler-Hi]

I wouldn't say its underpowered for a park flier EDF, but more power would make its flight performance better. Top speed with my 300 watt setup is probably 45mph. I fly off of pavement myself, and would suggest this method for the maiden. Be prepared for a 100-150' run out.

I had to have the same length run out for the HL F-18 stock. I would definitely upgrade to a better powerplant right out of the box. Their powerplants that come stock in these EDFs are JUST enough to get them off the ground and fly. The performance is usually seriously lacking.

[K CLOSE]

I got the Gripen yesterday, and a quick inspecton shows it to be rather similiar to the Mirage.???? I'm stuck at work for a bit, so I won't be able to build it for a while. Once I get to "run it up" I'll check the power. I figure if it seems good I'll trim in a bit of up elvr. and give her a run down the runway.:silly: If it's weak-- is there a better brushless I can just drop in there? Or is this a bigger motor/fan/esc situation?

[Angler-Hi]

I was looking at the HL website but it doesn't say what mm fan unit it uses. I'm assuming it's 55mm. Talk to Don aka The Don. He's a fellow watthead and has his own site for great upgrades.
http://donsrc.com/cart/index.php

He has definitely helped me with choosing an upgrade for my Intruder.

[bhatch21]

I believe the stock fan is your standard Chinese 5-blade 64mm fan with a 20mm motor housing. I'm not sure what the shaft size is on the stock motor, probably 2 or 3mm. Angler is right, Don has "Wicked" motors with standoff adapters that will fit in the stock fan. I also fly my Gripen with a little reflex in the elevons.

[Angler-Hi]

I stand corrected...64mm. Thanks bhatch21.

[K CLOSE]

Thanks guys. I'll post again once I've checked her out

[K CLOSE]

Well, I finally got a chance to start on the Gripen. Plane looks great EXCEPT (a)- no canopy was in the kit and (b)-the battery is wired in reverse. Gotta call Hobby Lobby again.:sad:

UPDATE
I finished up the build except for the missing canopy, not that there is really anything to the build-pretty straight forward. I pulled the main landing gear mounts and reversed them like bhatch21 suggested. Also set her up for minimal throws for the maiden. I did go ahead and line the rear ducting. The interior of the "thrust tube" was very rough and from what I have gleaned from reading thats a big no no. I used heavy, smooth card stock poster board and mounted it under the rear lip of the fan, scotch tapeing the seam at the inner and outer overlaps. I didn't legnthen or restrict the ducting, just lined it so it was smooth. Good idea or no???? I could pull it out if this is a bad idea. Also, My Gripen balances just aft of the stock mounts. I kinda thought I'd leave it for the maiden, as it should be slightly more stable this way, no?
Awaiting Pennys to be thrown at me--two at a time:p>.

[bhatch21]

Also, My Gripen balances just aft of the stock mounts. I kinda thought I'd leave it for the maiden, as it should be slightly more stable this way, no?
Does it balance behind the stock CG location or behind the main landing gear mounts? I think behind the main LG mounts is too far aft and would be tail heavy. The plane will be less stable in this condition. Check the suggested CG in the manual, it gives a measurement from both the nose and tail cones.

[K CLOSE]

Sorry for the confusion, poorly worded on my part. I ment just aft of the stock ballance point, maybe a 1/4 inch or so. I belive you said your flying at about 1 1/2 inches rearward, so I figure I sould be slightly more nose heavy.

Called H/L again today. Got the OK to re-wire the battery:) and I should see a canopy in 5-7 days:(. Any thoughts on the duct "liner"????

[bhatch21]

Ok, I understand the balance issue now. It should fly there, just make sure to have at least 1/4" reflex in your elevons. I haven't done any testing with regards to duct work, but the smooth liner sounds like it can only help. Good luck.

[K CLOSE]

just make sure to have at least 1/4" reflex in your elevons.
::oOk, heres where I'll show my ignorance. What does that mean ????. I've never had an elevon plane before, is this something akin to differental?

[bhatch21]

Reflex just means "up" pre-trim (as in pulling back on the stick). Set your trim sliders to neutral and use the control rod clevises or EZ connectors to raise the trailing edge of the elevon control surfaces 1/4" above the wing. This counter acts the tendency of a delta (especially a nose heavy one) to pitch its nose down.

[K CLOSE]

Oh, ok. Thanks for clearing that up. I did put in a bit just because it seemed like a good idea. No where near 1/4" tho, I'll go back and crank it up.
H/L email says the canopy shipped today, so if I'm lucky I'll fly it within the next week or so.

[K CLOSE]

Well, I got the canopy yesterday. I mounted it up and snuck off for her maiden. It flys GREAT:tc:! I have no doubt that the help and tips everyone gave was a huge part of why it went so well. Now for a quick flight report for anyone who might be intrested in the Hobby Lobby/Starmax Gripen....

The build is easy, as you would expect in a RTF, so I won't go on about it. I found the power to be good, and I'd like to think my duct liner helped (probably didn't do a darn thing:Q). The plane needs a long run out like bhatch21 said, and I think turning around the main landingear like suggested helped her lift off. And you have to lift her off, she won't just power up and lift off on her own.

Once airborn it flys great. It really is remarkably stable and slows great for landing. I put it through a few moves on the second flight and found inverted flight stable. The loops were tight, and did not require any dive. Tight snap rolls require rudder, and then are quite fast. Rudder has a LOT of authority. I have the controls on the slowest possible throws, and set there it's very stable. I think once sped up it will be very responsive. I slowed it ( several mistakes high mind ) and tried a harrier type move and the Grippen just hung there like a kite. She will wobble a bit but very controlable, really neat stuff. Once I get brave enough it will make for cool landings.

One complaint:( - Flight times are short. Mixed throttle and no real areobatics found a first flight time of less then 5 min. Fortunately she dead sticks in perfectly:ws:. Timed my second flight at 4 min and the 1300 mAH battery took in 1000 mAh.

With my vast ducted fan experience ( two flights on this plane :Q ) I would highly recommend this plane to any lurkers out there thinking of trying their hand at their first ducted fan. Stable, fun and with a top speed around 40 mph it's a great way to get your feet wet. But I think I will be in touch with "The Don" before too long...:p>

Thanks again bhatch21 and Angler-Hi!

[K CLOSE]

Just one more note on the Starmax Gripen....
I snuck off today for a quick flight as I had a small window of opportunity to go fly. BAD IDEA on my part, as it was really windy. I mean flags snapping and real estate signs standing out at 3 O'clock windy- no exaggeration. Had to be gusts in the 40 mph range. But I went to the club field ( nobody else there, wonder why;-) ) and flew the Gripen- I was just dieing to give her another go. The end result was....
This plane is bloody brilliant. I set her on the runway and she was being blown backwards. Punch full throttle, ground manners are great with the steering nose wheel, and she's airborne in 10 feet. The field is on a hillside, and once above the tree line the wind was ridiculous. Full throttle into the wind requires a dive to make any ground progress. Turn left and low level flybys are at the 80-90 mph range. Turn back and climb/dive to chew your way back upfield. The whole time the plane flew FANTASTIC. I know it's no ball of fire, but the only other planes I've flown in winds like this are my GWS Zero and GWS based F2G. This was much more stable than them (Zero is still my favorite chunk of epoxy tho':Q). In high winds with the Zero the cross winds keep rolling it to one side or the other. I can only assume that delta wings are more stable than low wing warbirds.
But here's the best part:silly:-- if I ran out of power I knew I was done for. No way a dead stick would be anything other then death today. So I landed at about the 3.5 minute mark to be safe. I lined up on the runway, cut power and kept her level with the elevons and into the wind with the rudder. From about 18' high, modulating the throttle, she harriered down for a perfect 3 point landing. DEAD FLAT at my feet :$. Kept a bit of throttle on so she wouldn't get blown back wards, bent down and picked her up:Q. Best bit of flying I've done in a long while (maybe ever:rolleyes:), and as usual I was by myself. After that I was done, any other flights would tempt fate and were destined for destruction. That and the fact that I was too chicken to go again.
Anyway, it's one heck of a plane. I know there are many faster/better/more detailed jets out there, but for my fellow ducted fan newbies out there---you can't go wrong with this one. Flights are short and it's not very fast (my F2G Super Corsair is easily more than twice as fast), but its a great flying set up. There is basically no building and it's not very expensive, so your not afraid to take a chance or two with it playing around or learning stuff. To my mind it's a great start in the nebulous world of ducted fan.:eek: