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Infinity 90 Build

How good is it ?

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cymaz12/01/2019 18:13:18
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8443 forum posts
1160 photos

Beginning with the wing servos....ummm....this is going to be a long buildfrown.

Why do the manufacturers put a corner piece right where the servo is going? Had to be sawn out.

Why is there no backing plate for the servo horns. There are only short screws. This was changed. Found some thread horns with stiff backing plate that will never pull out. So spent an hour searching for stuff, good job I have lots of stuff!

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The clevis ends were held in by a self tapper. That had to go. M2 nut and bolt with a Kavan M3 pushrod end. The supplied rods are barely over 1mm and like cheese.

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cymaz12/01/2019 18:15:30
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8443 forum posts
1160 photos

Savox servos fit a treat with a bit of wing hole trimming

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cymaz13/01/2019 19:57:21
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8443 forum posts
1160 photos

I must be losing my touch. All afternoon to install two aileron servos. However, I really satisfied with the result. Properly supported horn, securely bolted through. They are not going anywhere. The pushrods are M3 Carbon epoxied in and tight. No slop, endpoints 140 each way. Servo horns at exactly 90* with no sub trimming.

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Peter Jenkins13/01/2019 23:33:40
1193 forum posts
132 photos

Looking good Cymaz.

Although it's too late to affect your choice of pushrod, I find that using turnbuckle type connectors is a great way to make small adjustments to the surface without having to use either sub-trim or unbolt the clevis to make the adjustment. It is also provides as much fine tuning as you'd like. See picture below. These are made by Secraft and available from MacGregors. The horns are Dubro large control horns and the packing under the horn is actually a piece of triangular TE stock! Ideal for sorting out the bolt travel through a shaped aileron.

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cymaz14/01/2019 06:18:08
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8443 forum posts
1160 photos

Thanks for that, now in my favorites listyes. The elevators will be done the same way. I have several lengths of carbon pushrod and all the links I need. Must keep hunting through the hardware bins and use stuff. I am thinking of M2 for each elevator half, just to keep the tail weight down.

For once I’m trying hard not to add lots of weight. The engine bay and UC plate will be strengthened with strips of carbon fibre. BTW, can I use Zap 30 min epoxy to wet and fix the CF to the wood ?

Bruce Collinson14/01/2019 08:38:28
338 forum posts

It'll be too thick to wet out properly, won't it? Will you have to either warm it up, or dilute it with acetone/meths? Why not stick to skinning epoxy, as it were?

BTC

Peter Jenkins14/01/2019 09:21:46
1193 forum posts
132 photos
Bruce is right. I tried 30 min epoxy and it is: too heavy; is too viscous and drags the CF fibres out of place; does not adequately penetrate the CF mat. The Easy Composite resin is far superior in all respects. I was very impressed with the results.
alex nicol14/01/2019 12:36:22
243 forum posts
6 photos

I've used zap 30 before with no issues........if you warm both bottles up in the microwave 10 - 15 seconds it's fine. The only thing is it'll go off a bit quicker so you need to work fast

cymaz14/01/2019 17:09:40
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8443 forum posts
1160 photos

Thanks all......I have got some resin/ hardener some for fibre glass some where in the garage....will hook it out and have a play with both. I will set up a couple of test pieces and take some notes. Might be interesting in the difference between epoxy and fibreglass resin, we shall see..

The elevator closed loop crank arrived today. Nice bit of kit. I used the same on a bid biplane or two. The DLE 20ra is due Tuesday/ Wednesday. We have an 84dB @7m limit at St Austell DMC. So at the same time as getting the engine from RCWorld I purchased a couple of pepper pot mufflers for the ends of the exhaust tubes. They may prove of use, they may not. It might be a case of getting the stock exhaust modified......exciting isn’t it teeth 2

Edited By cymaz on 14/01/2019 17:17:20

cymaz14/01/2019 17:22:48
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8443 forum posts
1160 photos

BTW! Those Savox servos are a nice bit of kit. Very smooth and precise. And they fit onto Futaba horns. Might be persuaded to change from the Hitec 625mg.

cymaz14/01/2019 17:56:16
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8443 forum posts
1160 photos

Look what I’ve just found party

Fibreglass matting ok? Or should I go with carbon fibre that is already ordered?

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Peter Jenkins14/01/2019 18:32:48
1193 forum posts
132 photos
I'd wait for the carbon fibre. It's both stronger and lighter than fibreglass. Epoxy resin is also much heavier and more viscous than specialist carbon resin. Properly applied it's much better than fibre glass and lighter. One thing you must always remember on a specialist aerobatic aeroplane is to keep weight down. Vertical performance will be undermined as weight rises.
cymaz14/01/2019 18:36:47
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8443 forum posts
1160 photos

I will wait and do this at the weekend when I can use a warm kitchen. Thanks for the advice

Peter Jenkins14/01/2019 23:50:11
1193 forum posts
132 photos

While you are waiting for your CF, I thought you might like to see how my DLE35RA fitted into my Majestic. The Majestic is a 2000/01 design by Christophe Paysant Le Roux (8 times world aerobatic champion). The design is dated but I bought this to get through a full Aerobatic C schedule rather than fly 2 electric flights. The engine installation is just like the one you are facing here.

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I had to fit the throttle and choke push rods and fit the fuel pipe before fitting the engine in place. You need 3 hands for this job! The other problem was tightening the mounting bolts but the provision of cooling holes and slots allows an Allen key with a ball driver (must be a good quality one or the ball will slip in the socket head) and then using a tube over the end of the Allen key to tighten up the bolt.

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You can just see the top bolt in this photo. The bottom bolt is accessed through the hole at the front of the cowl.

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It is a right PITA!

cymaz15/01/2019 05:30:13
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8443 forum posts
1160 photos

Thanks Pete. It does seem tight. The DLE20ra is beam mount but I expect it to be just as tight,

Bruce Collinson15/01/2019 08:50:13
338 forum posts

Cymaz,

Agree re Savox servos.

Your engine mount ought not to be anything like as tight, with beam mounts, but I will be fascinated to see how the soft mounts adapt to a DLE. The throttle linkage might be interesting though, probably more so than the choke lever.

How much carbon are you intending to install at the front? I'd have used the glass, although perhaps a lighter grade. Can't see the weight being an issue, especially if your tank is going where designed.

Don't hold your breath re the pepper pot inserts, they just seem to stifle the engine although you might just creep below 84dB. Too many compromises, am on the cusp of swapping mine for a 120 4 stroke. The only thing we never got round to trying was putting steel wool in the original exhaust but the bottom line is that it's too small to have much effect. You might be able to smuggle a proper pipe in though.

BTC

cymaz16/01/2019 16:53:11
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8443 forum posts
1160 photos

 

Began tackling the elevator linkage. I did buy a World Models elevator crank from Steve Webb. However, the black and white poor line drawing defeated me. So after a couple of emails the brilliant sales people at WM sent me this....

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So much easier to understand. I’ve added a couple of ply plates drilled out for a 10mm hole to fit in the tail and we are ready to fix in.

Edited By cymaz on 16/01/2019 16:55:34

SR 7116/01/2019 17:20:40
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266 forum posts
61 photos

Now thats neat Cymaz

cymaz16/01/2019 18:36:03
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8443 forum posts
1160 photos

yes

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Bruce Collinson16/01/2019 20:51:10
338 forum posts

Mind the pull-pull rudder cables, now that you’ve narrowed the inside of the fus just in front of their exit slots. I put c. 4” plastic tubes and liteply brackets, to keep the tubes clear of the bell crank, fixed to the former in front of the bell crank. It’s slightly tight back there.

BTC

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