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HSD MB339 review anyone???

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Old 10-25-2018, 10:08 PM
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Originally Posted by ms200a View Post
Hi All, I have the Boomerang MB-339, 25 flights todate, arizcowboy was very helpful in the cg and other info, this is my setup;

​​​​Aileron High 20mm, Mid 15mm, low 10mm. expo 10% on all, I like mid position the best. Elevator high 23mm, mid 19mm, low16mm,15% expo all. Again I like mid position the best. I also slowed elevator servo down a touch to keep from inducing pitch oscillation and getting into the huck a buck when landing. Flap Mid 13mm, Full 40mm, mixed in crow Ailerons up10mm, CROW ONLY with FULL flap! Flaps slowed down to soften any pitch change and look more realistic on ground. Flap elevator mix, none on mid, 2.6mm down elevator on full Flap.
CG. location Larry Roper Boomerang jets said; The Leading edge of the wing tip and arizcowboy (rcuniverse) said his HSD is at 135mm from where wing meets fuse. Mine is now at 131mm from leading edge where wing meets fuse. With a swept wing this can be a bit tricky to measure where the balancer makes contact to the wing. Because the trailing edge has no sweep, if you measure from trailing edge forward it works out to 257mm, with cg set at that point, it still needs some down elevator in inverted but not much. FWIW my flying style is lazy, I just like to turn, roll, loop, split s, Immelmann, that stuff, I fly with an old p-70 for power at a little better then 1/2 throttle and at full across the deck to build up energy for vertical stuff. I can fly for 7min but keep it around 5 for fuel cushion incase someone needs to land or has trouble. The wing tanks will also help slow it down and you'll need to stay in the power base to final which for me is good because the P-70 spool up time is measured with a calendar. The crow acts like a bit more washout. I rate all my planes this way "would I buy it again" Yes absolutely, already saving for a 2nd one to dress gray camo. Fly's like a trainer because it is one, Qualifies as a warbird because it is one. As the Italians say Ciao



ms200a,

Thank you very much for taking the time and providing your settings which are a big help! I have one concern which is the landing speed. We have a rather short runway about 120 meters paved with no room for mistakes and unfriendly run offs. Can you please advise the MB339 is able to land slow without having the risk to stall
Thanks in advance
Regards
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Old 10-26-2018, 06:04 AM
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Originally Posted by extra 300 View Post
ms200a,

Thank you very much for taking the time and providing your settings which are a big help! I have one concern which is the landing speed. We have a rather short runway about 120 meters paved with no room for mistakes and unfriendly run offs. Can you please advise the MB339 is able to land slow without having the risk to stall
Thanks in advance
Regards
​​​​​​ Hi extra 300 wow thats a short field. I'd say landing speed would be in the 48kph range (just a guess). I'm going flying this am. I'll pace off 120 at the dry lake see how i do, let you know.
Mike
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Old 10-26-2018, 06:41 AM
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Originally Posted by extra 300 View Post
ms200a,

Thank you very much for taking the time and providing your settings which are a big help! I have one concern which is the landing speed. We have a rather short runway about 120 meters paved with no room for mistakes and unfriendly run offs. Can you please advise the MB339 is able to land slow without having the risk to stall
Thanks in advance
Regards
Unrelated to this particular airplane but do you run air speed telemetry? When I started using airspeed telemetry it made landings so much more consistent and landing on shorter runways much easier.
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Old 10-26-2018, 01:59 PM
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Hi MS200a

Thanks for all the details. From what you see, do you think the gear / gear mounts would hold up on a semi rough grass field ?

thank you.
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Old 10-26-2018, 02:00 PM
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Originally Posted by extra 300 View Post
ms200a,

Thank you very much for taking the time and providing your settings which are a big help! I have one concern which is the landing speed. We have a rather short runway about 120 meters paved with no room for mistakes and unfriendly run offs. Can you please advise the MB339 is able to land slow without having the risk to stall
Thanks in advance
Regards
​​​​​​
Ok logged another 3 flights no wind. Paced off 100 paces which is about 300 Feet on hard surface. Taxied out, set flaps to mid, held brakes throttle to full then with turbine spooled up release brake. Plane was easy to hold on center, rotated at about 170-180 feet (normally I delay the rotation for more speed) shallow climb to continue to build speed, retracted the gear and flaps all good. Landing; I will reference throttle to stick position as I don't know if 1/2 stick = 1/2 thrust output. So at 1/2 throttle stick I drop gear then set flap to full and as plane slows, advance throttle stick to aprox 3/4. Then as I turn base I reduce to aprox 1/2 and hold that until I turn final, then reduce to aprox 1/3. when I know I have it, reduce further with nose up at about 10-15 degrees, the plane will give up energy with wing tanks attached full flaps and crow so don't get too slow. I set down on mains letting it slow on it's own then stuck the brakes hard! Stopped in about 100" feet.
You should be fine at you field. FYI this is my first experience with electric brakes. They do not apply evenly and if you ease into them you will get a skid to strong wheel. If you hit them hard then ease up no problems. Because we have a larger field I just let it roll out then stick 'em and it stops straight.
As a point of interest the plane is short coupled so don't be afraid to pull the elevator in a turn like a foamy, nose will drop a bit in a lazy turn and hold true in a tighter one. Also I have my brake slaved to my elevator with DOWN they come on at about 1/2 and full on at full down elevator. It's an old school set up but if I have to abort the stop and punch it, then the brakes are off and not fighting me and I"m not fumbling for a switch or knob.
Good luck to you keep us posted
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Old 10-26-2018, 02:12 PM
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Originally Posted by DUCMOZ View Post
Hi MS200a

Thanks for all the details. From what you see, do you think the gear / gear mounts would hold up on a semi rough grass field ?

thank you.
Yes the gear and mounts are quite robust, and trailing link is a good choice for bumps. FYI both pinch bolts on both of the mains loosened, so I would lock-tite them. The pinch bolt is a star bit and the head will not clear the gear frame, but you can back it out a bit put a drop in the hole and let it creep in, then a drop on the other side and tighten it back up. since i did that they have stayed snug. Also the ventricle fins and wing tanks screws will loosen lock-tite those as well

Last edited by ms200a; 10-26-2018 at 02:15 PM. Reason: more info
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Old 10-26-2018, 02:16 PM
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Originally Posted by why_fly_high View Post
Unrelated to this particular airplane but do you run air speed telemetry? When I started using airspeed telemetry it made landings so much more consistent and landing on shorter runways much easier.
Stock tank and its 75oz
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Old 10-28-2018, 12:12 PM
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Thanks again for your detailed description for take off and landing on a simulated short field, I really appreciate your efforts, it gives me confidence to go ahead and start my build. I will have a K-85 powering my MB339, will also incorporate a few of the upgrades, knowing that I have one of the first kit produced.
Dany
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Old 10-29-2018, 06:43 AM
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Regarding the pinch bolts. I believe that this kit uses the JP hobby retracts like so many others. The pinch bolt work but a hard landing or time can cause them to loosen or the main struts to turn. You would be served greatly by drilling and tapping the retract and placing a small grub screw to help hold the main struts and keep them from turning. That way, even if the retract pinch bolt loosens, the struts will stay in place and will not turn.
Tone
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Old 12-05-2018, 04:41 AM
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Question on turbine size for this plane.
The description on BananaHobby states : "Engine is ready for your 80kg to 140kg turbine"
I have a JetCentral Cheetah SP (140 size) available. I fly from a grass field, about 200m long.
Is it practical to put a 140 in this plane? Most people seem to be at the lower range of turbine size.
Also, on the Boomerang RC site, the turbine size range is listed as "Recommended turbine size 6kg - 10kg. "
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Old 12-05-2018, 11:14 AM
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Originally Posted by ltc View Post
Question on turbine size for this plane.
The description on BananaHobby states : "Engine is ready for your 80kg to 140kg turbine"
I have a JetCentral Cheetah SP (140 size) available. I fly from a grass field, about 200m long.
Is it practical to put a 140 in this plane? Most people seem to be at the lower range of turbine size.
Also, on the Boomerang RC site, the turbine size range is listed as "Recommended turbine size 6kg - 10kg. "
Well, 1 kg force equals 9.81 Newtons, so Banana Hobby is saying you want an engine that produces between 784 N to 1373 N. A Cheetah Se is a 160-class engine meaning 160 Newtons of thrust. So at a minimum, Banana Hobby has the units all off. Now in the detailed information they say " 8~12kg (17.6~26.5 lb) turbine engine (not included) " which is closer.

The airplane has a 68" wingspan and is listed to weigh 21 lbs with turbine and fuel. At 21 lbs, an 80 will push it very well. A 140 (or 160) would rip the wings off! I'd trust Larry at Boomerang when he says a 6kg (60 size) to 10kg (100 size) turbine. I watched him fly it off of grass at the Tiger Meet in SC and it did fine. Ask him what size engine he had in his.

Bob
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Old 12-06-2018, 05:27 AM
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I spoke to Larry about this.. He is a great guy and a very honest business person. I would listen to him ... He knows the plane because it is his design.

Andy
CRX Turbines

Originally Posted by rhklenke View Post
Well, 1 kg force equals 9.81 Newtons, so Banana Hobby is saying you want an engine that produces between 784 N to 1373 N. A Cheetah Se is a 160-class engine meaning 160 Newtons of thrust. So at a minimum, Banana Hobby has the units all off. Now in the detailed information they say " 8~12kg (17.6~26.5 lb) turbine engine (not included) " which is closer.

The airplane has a 68" wingspan and is listed to weigh 21 lbs with turbine and fuel. At 21 lbs, an 80 will push it very well. A 140 (or 160) would rip the wings off! I'd trust Larry at Boomerang when he says a 6kg (60 size) to 10kg (100 size) turbine. I watched him fly it off of grass at the Tiger Meet in SC and it did fine. Ask him what size engine he had in his.

Bob
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Old 12-06-2018, 03:33 PM
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Originally Posted by ltc View Post
Question on turbine size for this plane.
The description on BananaHobby states : "Engine is ready for your 80kg to 140kg turbine"
I have a JetCentral Cheetah SP (140 size) available. I fly from a grass field, about 200m long.
Is it practical to put a 140 in this plane? Most people seem to be at the lower range of turbine size.
Also, on the Boomerang RC site, the turbine size range is listed as "Recommended turbine size 6kg - 10kg. "
im sure the airframe can take it with proper throttle control, but the burger issue is flight time. Iíve stuffed a cheetah into a boomerang sprint, but it has a 4ltr tank. So flight times are still reasonable. I LOVE the cheetah, but itís a gas guzzler at any power setting. With only 2ltrs on board, your flight times will be VERY short.

Iím thinking of getting one of these from boomerang and will probably put a JC rabbit in it. Which is still better then a 1:1 thrust to weight ratio.
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Old 12-07-2018, 04:39 PM
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Originally Posted by afioretti View Post
I spoke to Larry about this.. He is a great guy and a very honest business person. I would listen to him ... He knows the plane because it is his design.

Andy
CRX Turbines
that's some funny stuff there. I like Larry , but he did not design the MB 339 . I talk to the owner of factory at least three times a week .

Last edited by arizcowboy; 12-07-2018 at 05:05 PM.
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Old 12-08-2018, 04:27 PM
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Terry... there is some serious discrepancy over the rights of this model and the design. Does not matter who the factory is.



Originally Posted by arizcowboy View Post
that's some funny stuff there. I like Larry , but he did not design the MB 339 . I talk to the owner of factory at least three times a week .
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Old 12-09-2018, 06:49 PM
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Originally Posted by afioretti View Post
Terry... there is some serious discrepancy over the rights of this model and the design. Does not matter who the factory is.

Come on. Is this like the time you said you were the only place to buy Swiwin engines? Weve been selling this plane for six months now. Larry (a great guy) is a vendor just like the rest of us. But he didn't design it. He imports it just like the other distributors selling it.
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Old 12-10-2018, 06:33 AM
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Andy, I have never said I was the only one selling Swiwin turbines. I set you up as a dealer, recall? I stated that I am the only one offering warranty service on Swiwin turbines in the USA.

As for Larry, I know him a very long time. He is not a vendor in this case, He is the owner of the company. If Larry asserts that he owns the MB339 composite design, I highly doubt he would make the statement without the necessary paperwork to back up his statement.

Andy

Originally Posted by RCJETWERX View Post
Come on. Is this like the time you said you were the only place to buy Swiwin engines? Weve been selling this plane for six months now. Larry (a great guy) is a vendor just like the rest of us. But he didn't design it. He imports it just like the other distributors selling it.

Last edited by afioretti; 12-10-2018 at 07:31 AM.
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Old 12-10-2018, 02:05 PM
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Originally Posted by afioretti View Post
Andy, I have never said I was the only one selling Swiwin turbines. I set you up as a dealer, recall? I stated that I am the only one offering warranty service on Swiwin turbines in the USA.

As for Larry, I know him a very long time. He is not a vendor in this case, He is the owner of the company. If Larry asserts that he owns the MB339 composite design, I highly doubt he would make the statement without the necessary paperwork to back up his statement.

Andy
Andy, you’re trolling again....

Now back to the people who have the 339, are eyeing the 339 or who are building it.

Last edited by RCJETWERX; 12-10-2018 at 02:09 PM.
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Old 12-10-2018, 02:26 PM
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..

Last edited by afioretti; 12-11-2018 at 03:52 AM.
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Old 12-10-2018, 10:09 PM
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Can you please leave the presumed ownership of this kit aside and focus on the composite MB339 characteristic and flight performance?
Thank you
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Old 12-11-2018, 06:36 PM
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Absolutely. I have spoken to Andy offline and I believe he now understands how this jet came to be.

Back to the mb339.
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Old 12-12-2018, 02:16 PM
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I would also like to hear more about this wonderful looking plane. Iím very interested in getting one.
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