Magic Hand RC 73" Yak build thread

[maineflyer]

Nitro,
Here are the pics I promised and one of the pump set up.
Jeff

[maineflyer]

Cowl & Canopy
I got some work done this morning on the cowl and fit it along with the canopy to the fuse. No issues to speak of but I had to cut more of the cowl than I would have liked to get it to fit over the muffler and allow it to be attached to the fuse. The canopy slides right under the rear fo the cowl in the front and attaches using 2 hex head bolts into pre-mounted blind nuts. Two thing I am going to do is take some canopy glue and follow the mounting points of the canopy and add some more glue there and cover the front of the fuse with black ultracote so that any fuel cannot enter. I noticed the front of the EF yak comes pre-covered and I can see impending issues with the Pitts muffler blowing exhaust back into the fuse. so to prevent this I will cover the entire fuse front with some black ultracote. I will probably mount the Hitec 225 throttle servo in the front end right behind the fire wall. I also mounted a coule of vinyls from TBM on the tail "The start of a little bling"!
Here are some pics!!
Jeff

[maineflyer]

Done:
I finished the plane up this morning except for balancing. I have the throws set for 3d and a lower amount. the plane came in at 11 lbs 5 ozs or a 25.89 oz per sq'. All up ready to fly weight. I will be taking the spats off before flying on the grass so that should save an ounce or 2. Here are the final pictures. I hope to have some flight reports soon. The speed of the servos with the A123 and the amount of throws I can get is OUTRAGIOUS!!
Here are a few pics.
Jeff

[maineflyer]

Maiden:

I got the plane out to the field today and got the motor running good. The pumped 1.60 was spinning the APC 18x6 at just over 9,000 RPMs and idling at around 2,000 with good transition. I wish I had some video but I couldn't find a camera. We did get some pictures.
I had the balance at 152mm which seemed ok (just a touch of down elevator inverted. First flight was pretty much the usual shake down. I little aileron trim and some rudder. The plane tracked ok but was pitch sensative due to the throws I had set. (all I could get on high rates with 70% expo) and about half that on low with 30% expo. Knife edge on low rates was very good but needed some coupling which I thumbed out (Pulled to the gear). Inverted spins on high rates were very, very flat. I brought the plane in a little hot to see what it would do and the glide was very nice. I went around and lowered the idle some and it came in over the runway and settled in nice and neat. Taxied back and refueled.

I have to say the pumped 1.60 started and transitioned like a dream. I was very happy with it knowing there was only 4 tanks through it.
The next flight is where the problems began. I added 50 % expo on the elevator low rates and this cured the pitch issues immensely. I just got back into the air and did a respectible rolling circle and notice the engine burbling some so I brought the plane by at about 30' and it seemed to smooth out so I pulled up and added throttle and the engine quit. So here I am in a nose up attitude with little airspeed at about 45-55' over a plowed field, down wind of the field. I pushed the nose over to get some speed and the only option was to pancake it into the field. Well needless to say light ply and balsa in a plowed field don't equal a happy outcome. The gear immediatley pulled out and then the prop caught the dirt and fulcromed the engine mount and fire wall out and the throttle servo and mount came loose. The cowl is totally trashed but other than that, the fire wall and gear mount everything else is unscathed. I looked everything over once I got it home and the prop, spinner and engine are all fine. Wings, tail and canopy don't have a scratch.
I also found the cause of the problem when I was going over the engine. The one thing that didn't make the trip was the glow plug. When I preflighted the plane I went over everthing at home and all was ok. I can only think that it worked loose during all the preflight fiddling and I didn't think to torque it down before the first flight nor did I check it after.
MY FAULT!!
Anyway, the plane flew well for what I did with it and I will be repairing it for more flights to come. I will call TBM and order another cowl and have at it.

Here are a few pics of the plane.
Jeff

[nitrobeast]

I am finally getting back to this project. I'll be running the engine with the pump for the first time today. Hope i can get a nice tune on it and get motivated to finish it...

[maineflyer]

Nitro,
I have mine fixed and have flown a number of flights with it. I have the CG currently at 6.5 inches and it flys well at that CG. I am still tuning the plane but like how it flys. I have probably 10 flights on it since the maiden. Let me know how yours comes out.
Jeff

[nitrobeast]

	Quote: Originally Posted by maineflyer
	Nitro, I have mine fixed and have flown a number of flights with it. I have the CG currently at 6.5 inches and it flys well at that CG. I am still tuning the plane but like how it flys. I have probably 10 flights on it since the maiden. Let me know how yours comes out. Jeff

Jeff

I think we got the engine/pump set pretty damn good!! We let it idle for 40-60 seconds and then full throttle and all was well. High end screams and low end is nice too. 1.60 makes great power.
Now i must get this thing done.
Are you running a 18x6w prop? I was gonna ask you about the cg since the manual i have is for the smaller one.
Did you do any mods to the firewall? Hows it holding up?
Rui

[maineflyer]

Rui,
I am running an APC 18x6W and it tachs around 9,000 and idles at about 1,650 or so. Transition is fast always but it sounds different sometimes in the air. I am begining to think it might just be normal noise as the engine unloads going to idle. It will take some time to unwind down to idle as I mentioned earlier. So don't forget to extend your final legs or you will be overshooting your landings. I have my CG at 6.5" from the leading edge. I would start yours at about 6", the plane flys well at that CG and then back it up some from there if you want a little more rearward CG. You will most likely have to put the battery on the side of the motor box to acheive that 6" CG and if you want to go back further you can just back the battery up into the fuse. I had to add a couple of ounces of lead to the motor mount to get the 6" CG at 6" on mine. Good luck and keep me posted!!
Jeff

[cyoung450]

MaineFlyer,

Sorry to read about your mishap. Very nice build thread too.

I have been flying gas for about 2 years now and sold everything Nitro I had, BUT I really want one of these 73 inch planes for the simple fact of convinence. AND my Buddy has one in the box that he doesn't want and is going o let me have it for a very cheap price, so all I need now is a GAS engine. Has anyone tried a 26cc engine in ths yet? How about a 40cc? I was thinking of this engine..

http://www.maxfordusa.com/spe-43.aspx this is a 43cc engine, and weighs 51oz with ign and muffler
The os 1.60 weighs in at 42.5 oz with muffler
There are a couple of other 40-45cc engines out there that I am looking at, looks like 3 lbs is about what there are all at. The 26cc is just not enough power.

Any info would be great.

Thanks,
Conrad

[maineflyer]

Conrad,
I think the 43 CC would be a great set up. I would beef up the firewall and move your battery back into the middle of the fuse to acheive balance. I have been flying my plane at about 6 1/2" GC and it still has room to go further back. The plane is similar to the EF yak is size so I used their CG recommendations. I think I could go back a little further but think the knife edge coupling will get worse as I go. I would also check the AMA magazine. Troy Built has an add in there for this plane at $200 something through that add. I would call them on it. I know they are modding the plane slightly and I beleive adding a CF wing tube and possibly gear for the plane. They now have an aftermarket tube for around $45 I think. If you could get the plane for the lower price and buy the tube (weight savings of 5+ oz) Your gasser should come in right around 12lbs depending on batteries.
I think you will like the plane.
Jeff

[kencz]

Still building mine and going to put an OS 200 fourstroker in it.

Any updates on your project? Did you ever get it repaired and the bugs exterminated?

Ken

[maineflyer]

Oh ya, been flying it all summer and it is very nice. It harriers both ways really good. Main gear are a little soft and change the tail gear out for something more robust. Mine bent so many times just from taxiing that while bending it back after a perfect landing it broke in 1/2 thus ending a beutiful flying day after the first flight. You will be very happy. Also make sure your stab incidence is 0 on both sides.
Jeff

[kencz]

Hi,
Did you go with the included wing tube? It seems like an awful heavy piece of pipe compared to similar planes I have examined.
TBM is now sell a CF tube for about $20 and I'm thinking it may not be a bad idea.
Your comments?
Also, which Parry Pump are you using? Some folks are suggesting the oscillating version that basically works off vibration.
Your ideas?

Thanks,
Ken

[maineflyer]

I would put a CF tube and gear in immediately if they have them. You are right the tube is WAY heavy. It sould save you 5 oz easy. I have a VP-30 (pump) installed and the backplate drilled which is very easy and it works great. I have the tank back against the wing tube. I haven't got a CF tube for it yet as I currently have the Yaks brother on the bench (EF 74" yak) Same setup with A-123s and Hitec corless digis around. I have a NIB 1.60 and pump waiting for her. Once I fly the EF some I will probably tweak the Magic Hand some and buy a new tube.
Thanks
Jeff

[Captinjohn]

Two vary simular aiplanes![ATTACH][/ATTACH]