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Pete Tindal Sukhoi Re-engine

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Peter Hawtin22/09/2008 13:05:00
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59 forum posts
8 photos

I though some of you may like to hear about the changes I recently made to my Pete Tindal SU26MX Sukhoi.

The 27% Sukhoi 26MX (2.1mtrs),  originally had a Zenoah 62 fitted, and it aways felt like an aerobatic truck rather than the light weight it should have been, but the design of the model needed the weight on the nose to get it to ballance. I never really liked the Zenoah, being a pain to start and when it finally gave up the ghost I put the Sukhoi in the back of my garrage and their it stayed. 

I recently was shown a new 51cc petrol motor that like many others now starting to emerge is purpose built for model flying rather than modified strimmer engines. The Area 51 comes complete with exhaust, ignition and substantial stand-offs and the measurments seemed about right for my Sukhoi.

I liked the Area 51 as the mounting lugs on the motor are very substantial, and the supplied standoffs are also well made with 5mm mounting holes for the motor end, and 6mm fittings for the fire wall. This gives a really solid mount on to the fire wall without adding too much weight. The Peter Tindal Sukhoi I have has a Kevlar honeycomb sandwich construction on the fusealarge, and the firewall is a glass fibre moulding with a plywood plate glued on the rear. The larger fittings on the Area 51 really stiffened this firewall up compared to when the Zenoah was fitted. The Motor was supplied by Gashanger.com and Paul supplied a great mounting template enabling you to see exactly where the holes and the throttle cable needed to be drilled. Its good to find a supplier that has the service and knowledge to support its customers.

The Sukhoi used to weigh in at 7Kg, now with the area 51 mounted slightly forward (6mm) of the Zenoah and some changes to the main spar and UC (aluminium to Carbon), it now weighs in at just under 6Kg.  That is with 2 x 4200 5 cell receiver batteries through an SM services battery backer just in front of the spar to keep the model balanced, drive the smoke pump (yes I like to show off) and for added safety.

I have a problem with ground clearance, so max prop size is 22" and that's cutting it really close as it trims the grass on take off! I am looking at ways of adding 30mm to the end of the carbon undercarriage or I am going to try a 20 x 10 3 blade prop to see how that feels. Has anyone used a 3 blade on a similar motor, if so what size/make? What was it like?

Peter

Peter Hawtin22/09/2008 13:05:00
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59 forum posts
8 photos

Part 2

Area 51 has now done about 45 mins running in the Sukhoi; I am using Halfords fully Synthetic oil at 30:1 and will leave this for at least another hour of running. The carb was originally set to 1 ¾ out on low and 2 1/8 out on high, all I have done is take the low needle in till its picks up reliably but the High still has not been touched. 

Its still rich on the bottom end and burbles on 1/3 throttle, and will need perhaps a 1/8 turn in to get it about right. ( its about 1 1/8 out now) and the high needle will need some work to obtain the best once I change to 50:1 oil.

The good news is that with the motor still running a rich it has amazing power and pick up, putting the Zenoha to shame.  For the first hour I am using a Graupner G sonic Pro 22x8 prop. It is a bit on the small size and pulling 8400 on the ground, it must be unloading to over 9500 in the air(if not more), but it sure pulls well!! 

I have tried a Graupner G sonic Pro 22x10 prop to see what sort of revs I can expect, and this with no mixture change gave just under 7400, running VERY rich.  I will complete the first hour of running on the 22 x 8 prop and then go up to the 22 x 10 and start taking the low end in, then we will see what the Area 51 can do, and its pretty good now.

Mind you the sound of that prop at 9000+, is like music, we have one of the worlds best full-sized display teams (The Blades) based 2 miles from our strip who fly the Extra 300 and the noise the Area 51 makes on the 22 x 8 is just the same. 

One thing I discovered about starting the Area 51 is not to be too agressive. I was used to the Zenoha...tough leather glove and give the prop a good belt. The area 51 is amazing, couple of flicks on the choke, then just push the prop over TDC to start it purring. Give it a hard flip and it sulks from miss use.

I just need to find an exhaust that can quiet the beat a bit without loosing too much power. I cant fit a canister or pipe (no room) unless its less that 8" as I will have to fit it across the airframe behind the motor.

Peter Hawtin26/09/2008 18:52:00
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59 forum posts
8 photos

Had a disaster on the Sukhoi, with the left Aileron servo arm cracking and spining on the shaft. This happened during an inverted flick, leaving the right aileron at 20 degrees up!

 Managed to get the model down in one piece, but broke the rudder, undercart and exhaust outlet pipe. No big deal as the rudder is already fixed, and CArbon Copy are producing me a new Undercart and it should be with me next week.

 The exhaust however is another thing, it was a bit noisy anyway, so I have decided not to get a new standard exhaust, but have contacted Weston UK to produce a custom in-cowl unit. It will be interesting to see how it effects the motor.

Peter

Dusty27/09/2008 19:53:00
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1632 forum posts
560 photos
Wow Peter good job on saving your model, sounded like it could have been alot worse! post some pics of the smoke pump in action
Peter Hawtin27/09/2008 20:31:00
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59 forum posts
8 photos
http://www.modelflying.co.uk/sites/3/images/member_albums/32729/P1010004_1.jpg


http://www.modelflying.co.uk/sites/3/images/member_albums/32729/P1010014_1.jpg


http://www.modelflying.co.uk/sites/3/images/member_albums/32729/P1010015_1.jpg


http://www.modelflying.co.uk/sites/3/images/member_albums/32729/P1010016_1.jpg


http://www.modelflying.co.uk/sites/3/images/member_albums/32729/P1010023_1.jpg


http://www.modelflying.co.uk/sites/3/images/member_albums/32729/P1010017_1.jpg


http://www.modelflying.co.uk/sites/3/images/member_albums/32729/P1010002_1.jpg


http://www.modelflying.co.uk/sites/3/images/member_albums/32729/P1010007_1.jpg


I now know how to loose Lift on a big plane !!! Both Ailerons 20 deg up needs virtually full elevator to keep level, The main problem I had was the rate switch is just above the right stick, and struggling with almost full left aileron and up elevator, there was no way I could reach the rate switch...xome more movement and expo would have been so usefull!!

I have all the bits to get it finished this week, Carbon Copy, had my custom under cart delivered in 3 days, and Gashanger.com, has sorted out the standard exhaust 2 days after speaking to them.

Got to say its good to have the support of good suppliers.

Here are a few pics of the instalation, please bear in mind the model is over 5 years old!!

Peter

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