New Product 3dHobbyshop 57" Sukhoi Su-26mx

[BoneDoc]

Congrats Adam. Your life will never be the same ... (in a good thing ).

[bill clark]

Originally Posted by bill clark

when I put my E-Sukhoi together I used my spare motor (Hacker A50-14s, 550kv heli) and my batts from my Razor 10s heli ( 2 TP 25c 3850's in series) the batteries were pretty tired and would only hold 15.5volts wide open making 7.5lbs of static thrust on a APC 15x7e. ive been flying it this way for a few weeks. I bought a new TP 30c 3850 5s and a Xoar 15x8 knowing it should pull that prop with the new battery but when i started testing i was pleasently surprised. what i found was.........

prop rpm amps volts watts thrust

apc 17x4w 8645 76 18.73 1423 12lbs2oz!!!!!!!! 2-1 power to weight
xoar 15x8 9000 72 19.18 1381 9lbs13oz
apc 15x6w 9000 62 18.86 1169 9-1
apc 15x7e 8750 77 18.86 1452 8-12
apc 15x8e 8086 85 18.25 1551 7-13!!!!!!!!
old battery on apc 15x7e
7400 52 15.5 806 7.5
these test were performed in the plane with a digital fish scale and my
eagletree data logger and were repeated to make sure i had good data.
interestingly my saito 115 pulled the 17x4w to 8600rpm and maid 14lbs (2 more than the electric)of thrust and thats probably because the prop was unshrouded and in the plane the cowl takes up alot of prop space. the 17x4 also is very quite but it is heavy cause its for nitro. the saito is rated at 2hp which when converted to watts is basically the same as the 17x4 electric. so now im off to the feild

my flight testing basically reflects what is shown above and that is that the Xoar 15x8 is the best all around of the props tested, outstanding vertical,followed by the APC15x6w and 15x7e. the 17x4w performed like it did static but is heavy to accelerate (nasty little amp spike). actually it was hard for me to tell the difference between it and the Xoar exiting hover vertically even though it made almost 2 1/2 more lbs of thrust. i'm going to set a switch to run about 85% throttle for most of my flying to keep the flight time up. As Scott says in his book, rediculous power isnt nessecary but its sure nice when you want to use it, like a 10 foot departure on a windy day.

[800mZero]

Originally Posted by AllBread

Good news:

The more I fly this plane, the more I like it. I think that it's the most rewarding plane in the 3DHS line-up that I have flown. I had taken some time off from it while it's power system was in another plane. During that time, I spent lots of time improving my harrier with the 47" Edge. Coming back to the Sukhoi, it took me a second to find the sweet-spot (both control and set-up wise) but once I had it, I realized what a harrier beast it is. I can lock this thing in with absolutely zero rock both upright and inverted now and it looks awesome with it's long fuselage making it's way down the runway in high alpha mode. Inverted fly-by's are real crowd pleasers and the tumbles are very high energy.

This plane doesn't just "give it to you" like the SHP does, but once you go through your setup cycle (cg, trim, thrust, etc.) and get used to it's handling, it flies like a dream and probably has the broader flight envelope (vs the 55" SHP).

Bad news:

I have a few spars this diameter from other planes and I grabbed the wrong (and, of course, shorter) one. After it's 10th high-g tumble of the day, I ripped the wing right off doing a parachute. There was surprisingly little damage after it's long, spiral flutter to the ground - smashed the cowl up and tore off the landing gear. Wing is fixable, but boy do I hate fixing airplanes. It will fly again, but I'm afraid it will be awhile.

Ryan

allbread--after almost doing the same thing myself I now take the carbon tube and scratch lightly in the surface of the tube the model name so i dont get em mixed up.

[mahak213]

I was at the field today flying my Sukhoi and on landing, I ended up ripping the gear out. It was a VERY smooth landing...so I was surprised when it went skidding down the runway on its belly . After inspecting it, it looks like the gear plate de-laminated. If you look closely at it, its a lot of thin ply pressed together with fiberglass like material. It ended up splitting along each layer and basically looked like it had just pulled the top few layers away from the bottom. Both formers are still intact, the only damage is to the plate the gear mounts too. I'll have pics as soon as they're done uploading.

I just started pulling all the wood out from the damaged area and in each former are notches that the plate fits into. None of these notches had glue in them. I was able to remove the scrap with just my fingers...

[mahak213]

Pics

[theKM]

Originally Posted by mahak213

Pics

dang... managed to pull it through the glass! Looks like there there may be a story attached to that one

Pop a new plate in there and she'll be good to go. Plate on the Edge went up to the front former, so if the Sukhoi's the same, may need to be slicing forward a little to dig the rest of it out to replace it right. That structure is super strong, which is a bummer if you manage to break it as replacing is a little more involved (but certainly worth the effort!).

[mahak213]

Originally Posted by theKM

dang... managed to pull it through the glass! Looks like there there may be a story attached to that one ...

Sorta had a feeling people would think that...doesn't matter.

Its already back on its feet, and the covering iron is heating up as I type. I'll test it out tomorrow if its nice, but there is rain in the forecast. If not, thursday it is. This plane flies so nice, I was more pissed my day of flying was cut short than the fact that the gear ripped out.

[Jerry Combs]

Originally Posted by theKM
dang... managed to pull it through the glass! Looks like there there may be a story attached to that one ...

Sorta had a feeling people would think that...doesn't matter.

I have had mine pull out like that more than once on landings that were fairly smooth including one that was done by a friend who is a very good pilot.

[800mZero]

just out of curiosity have you guys been filling up the gear plate "bay" with poly glue such as gorilla glue?

[Jerry Combs]

Mine was filled with gorilla glue. Later, I filled the bay with a balsa block epoxied in and still had the gear tear loose. I fly from grass most of the time and I may have hit a hole. I am going to try it without the wheel pants and see if that helps. If not, I think I am going to go to a 1/2" thick gear plate.

If you look closely at Mahak's pics you can see that the ply delaminated, mine did too.

[Tim Semeraro]

I CA all of mine, and when the CA drys, I fill the Area with Gorilla WOOD GLUE. It takes 24hrs to soak in and dry, but it drys very thin, and makes for a semi rigid bond. I have done this on 6, 3DHS planes, and Ive never had a gear plate come out. I can say that my 47" SHP, and my V1 40" edge took a beating(well over 100 flights), and went through many sets of LG. I sold them to people who are not great pilots, and they still have not broken.

[mahak213]

I guess this seems to be a common problem. On my repair I ended up epoxying a few layers together, flipping the grain of the wood each time. I then added notches that would fit into the preexisting ones in the formers. Seems fairly strong, and for good measure, I filled the bay with some Gorilla glue.

[bigbobed]

I got tired of repairing mine and gave it to a friend. He's an excellent pilot and did a good repair. Be interesting to see how he makes out.

[bigbobed]

After reflecting on the problem and finding I'm not the only one, I wonder if the problem is the cf gear? Those are pretty long legs with lots of leverage. Somethings got to give and it's sure not going to be stiff cf.

[blucor basher]

The one rule about aircraft landing gear is: No matter what type of gear or plate an airplane has, you will be able to find modelers who don't like it and have changed it and like it better some other way. We sell lots of carbon gear for Acromasters because people complain about the wire, we sell lots of carbon gear for little yaks because people complain about the aluminum, and other companies sell aluminum for our airplanes because people complain about the carbon. We supplied our 55" Yak and 55" Extras with aluminum which was tempered to bend before applying much force the plate, and we can't keep the carbon upgrades in-stock because nobody likes the aluminum bending, even though with the carbon, if they slam it, the wood will take the abuse rather than the gear.

It is for this reason that we try focus on proper landing technique, because this allows a pilot to have whatever type of gear he likes and own some very light designs. Also, grabby grass puts more abuse on gear than nearly anything else. You can see intuitively that a "harrier plop" looks damaging, but (provided the wheels roll freely) it imparts an upward force into the gear plate. When you see nuts torn through layers of ply and fiberglass, this indicates a *rearward* force, pulling back on the wheels and twisting the gear backward. Something has to grab the gear to apply this rearward force. Either grass has to grab at the wheels pants or a wheel has to fail to roll from some reason. The popular "one wheel pant in the hole in the runway" landing is an example of this rearward force application. In this case, especially if a pilot if forced to land on grabby grass, it is important to approach as slowly as possible. This points out that, although some pilots are afraid to land on asphalt for fear of damage (grass looks "softer" to many people) asphalt has the very, very important property of not penalizing you for a fast landing. Provided your wheels roll freely and you're pointed even close to straight ahead, you can set down on asphalt quite fast without imparting any large forces to the undercarriage. Grass is often not like that, whether the pilot realizes it before the landing or not.

Also, everyone should keep in mind that over the internet, no one can see your landings. I'm pretty proud of my landing technique, but someone else might think I'm terribly abusive...who knows. The point is, if he and I are talking about "smooth landings" we might be on completely different pages and never know it.