ameyam

I am close to finishing a GP Reactor Bipe. With my custom build and reinforcement the airplane will come out heavier. I estimated based on component weights that it is likely be be around 3.2Kg with 700g allocated to the engine (OS FS 91SII or 110A). This is still within the 3.1 to 3.4kg range in the manual but I still have to do quite a bit. However, I am also considering a DLE20 on it later.

Have two questions:
1) The issue is that the firewall is drilled out for a GP 90-120 mount. Based on my previous attempt to mount the DLE20 on another airplane, I noted that even when adjusted to its widest, the GP 90-120 mount is not wide enough for the DLE20. On that airplane I had to use the 120-180 mount but I cant use that mount here as the firewall holes dont line up and its a big hassle to make new holes so close to the existing ones (I will end up with slots rather than holes). The 90-120 mount can probably take the engine but then the two halves will not interlock as the bolt slot will needs to be opened. I think its just a bit- 2mm or so on each side. I dont want to open out the bolt hole as this wouldnt be secure. So my question is, should I grind out a couple of mm each side in the beams to allow the dle20 to fit on the same 90-120 mount? I think the engine mounting holes are fairly further inside the beams, not too close to the edge.

2) The airplane requires you to solder one side clevices on the pushrods. However, I have no soldering experience and I want to learn that now because I have already made a bit of mess with the tail hinging when the CA on the nylon hinges dried both times before I could get them in (local CA is a bit too quick drying, I didnt even get time to drop the bottle). I have 4-40 SS pushrods from Sullivan and Dubro spring steel clevices with spring retainers in good quantity. I am also using Dubro Heavy duty scale black-colour FRP horns instead of the stock

http://www3.towerhobbies.com/cgi-bin...?&I=LXD875&P=7
http://www3.towerhobbies.com/cgi-bin...&I=LXD937&P=ML
http://www3.towerhobbies.com/cgi-bin...?&I=LXFV03&P=7

These will also offer ease of adjustment and since the pushrods are SS, not MS, they should be much sturdier and corrosion resistant. But some on the field told me not to use them because they are likely to corrode fast in the humid Mumbai weather and because the threading makes them prone to snapping. Should I use them anyway? I could paint over the unused length after I am done for corrosion resistance

Will post pics if I can once I get the dle out of storage, its just too far back on the loft right now.

Ameyam

ameyam

Anyone?

opjose

For the firewall do this...

Get a wooden dowel and cut "plugs" from the dowel, almost to the size of the thickness of the firewall.

Glue them in place with epoxy. Once dry, sand so they are flush with the firewall.

Now re-do the mount PROPERLY as if there were no holes at all.

opjose

Soldering the pushrods is not a big deal.

"roughen" the metal pushrod with fine sandpaper. Do the same with the clevis if possible.

Mark the location of the clevis ( measure twice !!! ).

Put the pushrod on a holder of some sort that will keep the clevis in the proper position.... put the clevis in place and assuming you are using pre-fluxed solder, have at it.

Otherwise dip the clevis in flux, put in place and solder away.

Get the clevis and rod hot... Apply a bit of solder to the tip to wet the iron as you heat the clevis and rod... the wicking action of the solder will help distribute the heat on the metal.

Keep heating until you get the solder to melt when directly applied to the clevis or rod... at that point apply solder more liberally until it flows into the juncture.

Remove the iron and allow to cool.

You should end up with a strong solder joint.

ameyam

Opjose,

the pushrod run horn-to-horn on the ailerons is just 90mm, may be less when you factor in the larger spring-steel clevises I am planning to use. I think I can get away with full threaded rods there, will sheet them with silicon tubing to prevent corrosion and scratching the monokote in storage. For the rudder and elevator I am using aluminium servo horns. There I am thinking of just using a z-bend on a standard one side threaded pushrod as the servo horn has sufficient material to be drilled out.

With the engine, there are hardwood spacers for the blindnuts installed behing and I have fibreglassed over. To get them out, a lot of work will be needed with the dremel. I want to retail the stock holes so that I can use either a 91 /110 4C or the DLE later. Hence I has asking whether I should sand the 120 mount just where there is interference with the dle casting to fit the engine in that mount

Ameyam

opjose

I can't imagine that corrosion would be such a problem, you would want to encase the rods in tubing.

If they do get corroded, it may be time to change them out anyway.

IMHO a better solution is to assemble the rods, get them to the right lengths, fly the plane to make sure the trims are right, then remove the rods and dip them in polyurethane and let dry for a couple of days.

The Poly will leave a thin transparent coating behind.

Re: Engine.

You normally remove / fix this before fiberglassing....

The DLE is going to produce more torque and vibration than a 2 or 4 stroker.
I wouldn't reduce the beam thickness by grinding some material out... better to get a larger beam more suitable for that engine...

ameyam

I made a temporary measurement on the pushrod yesterday, its about 95mm with provision to adjust both sides. Its SS, so cutting with the dremel and standard cutting wheels in a plummer vice will be an exercise. Will do it on the weekend. Thanks for the PU idea, will try that

With the engine, I am going to need to check the CG once the airplane is assembled with engine temporarily strapped on. Am also concerned that even the custom wrap around muffler I have just received will not fit into the cowl, its that tight due to the right thrust. I am considering starting off with a FS91 but am worried the airplane would be too heavy for 3D (think it will be 3.4kg total). I also have the 110A, need to run in that. Frankly thinking gas is too much of a hassle on this one- best to keep the 91 of the Reactor 46 and the 110 for this airplane as originally planned. Health reasons may not permit me to fly this particular airplane till October at this rate so I am taking it easy for now, not pushing the build even though I have it 90% complete

Ameyam

opjose

Re: Engine...

Better to use what the plane was designed for anyway...