Taz_Hobbies

My Feedback: (15)

DLA-32 gasser going in my new GW MX2.

I have a 5 3/8" measurement from the firewall to the end of the cowl, measured at the centerline of the crank.
The DLA-32 (rear carb) with stock 2 1/2" long standoffs measures 6 3/8" from the firewall to the backplate of the spinner / prop hub. So if left unchanged, I'd have 1" of hub adapter hanging out of the cowl which is unacceptable in my book. To change to 1 1/2" - 1 3/4" stand offs is no problem, except I have to carve out some firewall to allow the carb to protrude backwards thru the firewall by about 1/2". I will allow for adequate clearance for the carb and airflow to the venturi, but does this sound normal and has anyone else run into an issue like this?

Any ideas fellas?

pe reivers

Do what you have to do.

Taz_Hobbies

My Feedback: (15)

Yes, I surely will. Just seems odd that a 30cc airplane doesn't exactly accept a 30cc engine quite as nicely as you'd assume it would.

mrbigg

My Feedback: (21)

I always plan for a hole in the firewall with a rear carb engine. I think I got lucky once and didn't have to have a hole.

pe reivers

It's impossible to make a plane that will exactly fit all 30cc-ish engines on the market. There is no dimensional standardization yet.

Taz_Hobbies

My Feedback: (15)

Okay, thanks. I just didn't want to get into hogging on the firewall if there was another option. Thanks again guys.

pe reivers

You may move the firewall back, or glue a "paper cup"* in, so the carb will not spit back fuel into the fuselage.

* or similar

Taz_Hobbies

My Feedback: (15)

Hadn't looked at that yet since the newstand-offs won't be here until Monday or Tuesday.
Trial fit the tail feathers and bolted the wings in place. Test fit the carbon gear & wheel pants. Ran into a couple little fitment issues, but nothing you wouldn't normally expect.

Some folks don't care for this color scheme, I happen to just love the "Green Bean"!

pe reivers

My B-inlaw has a green plane. You either hate it or love it.

kerwin50

That looks just like my Green Machine. She's a GW MX as well. I have a DLE 30 in her as well.
I drilled a hole and cut my stand offs down. In all reality it's just as easy to move the firewall back.
You'll want to fiberglass the motor box as well.
And change out the fuel tank.

kerwin50

heres some pictures of mine. This plane does like to come in hot. But she 3D's really well.
This is my 2nd fuse the 1st one got broke up a few weeks back.
Where'd you get yours from?

Taz_Hobbies

My Feedback: (15)

The glassing of the motor box is just a strength / vibration thing? I hadn't heard of that, but I will certainly add that to my list of things to do.
I ordered CNC machined stand offs, even though I thought about cutting them myself.

I ordered mine from Milehighrc after speaking with a fellow member at my club, and then promptly found it 3 other places for about $80 lower price! Go figure!

What size tank did you go with? I noticed the tank in there seems small for a gasser.

All of my stuff is on the bench except for 3 more servos which will be here next Wednesday. I am running Hitec 5645's on everything (2 on the elevator) except the throttle. My twin miracle switch is here, the Batshare, both 2300Mah A123 packs, the opticle engine cut off and of course the DLA32. I have 18/6 props to start with and we'll see where we go from there.

I am by no means a 3D pilot, I'd call myself more like a 1D pilot! I am more of a zip around, burn a couple holes in the sky, sunday morning sport guy. I hope she isn't too much ship for me.

kerwin50

O yes you will need to glass that motor box. If I had it to do over I'd move the fire wall. cutting a hole in the firewall really weakens it. I've had to rebuild it a couple of times.
I land the plane fast and don't try to slow it down much. She lands much better that way.
I was using a single servo for the elev but on the new fuse I went with 2.
With 2 servos on the elev she came out a tad tail heavy.
Make sure you have metal geared servo's.
I'm trying these servo's out now http://www.hobbypartz.com/33p-solarservo-d770.html

Taz_Hobbies

My Feedback: (15)

So here are a couple shots of the fitting of the DLA 32 so far. Really had to hog the firewall out to make her fit and I can't lie, I am very concerned about it. I am contemplating removing the 5/16 stand off shim and laminating a 5/16 ply firewall "doubler" in front of the original firewall for added strength. The biggest issue this will create is I will be unable to access the high & low speed needles nor will I be able to access the curb idle screw.

Small price to pay I guess for added insurance. What do you guys think?




  

kerwin50

I had to drill a hole on the motor box at an angle to access the needle valve, That along with a weaken firewall is why I suggested you just move the firewall back.
Although I didn't do it on mine because I no longer have the stock stand offs after I cut them.
Well once again RCU's server doesn't like my photos

Taz_Hobbies

My Feedback: (15)

I had considered your suggestion, but after a little more consideration, I decided to go this route and leave the firewall move as a last resort. With the interlocking motor box already assembled, I just didn't want to disturb the thrust angles and start over. But of course I will if this turns out to be unsafe.

I have seen several installations of 30cc gassers in the same manner as our by pilots who really wring their stuff out hard, all of which have had no report thus far of any failures of the firewall. I know myself, I over build planes, so maybe it's my "Bigger Is Better" philosophy that is getting the best of me.

And to add to my pressure, I am re-covering a Funtana S90 I purchased from an RCU member while trying to get the fabrication / fitting of the MX2 at the same time! I am addicted!

kerwin50

Yeah i've busted my firewall up once but I pieced it back together and fiberglassed and laminated it with 1/32 lite ply on the back side. I just fiberglassed the front side.
this was due to my motor coming loose and a dead stick/stalled landing

Taz_Hobbies

My Feedback: (15)

I meant to ask, what size fuel tank do you have in yours?

kerwin50

I think it's a 10 or 12 oz dubro. The stock tank leaked after time.

kerwin50

BTW here's a really great build an fly thread on your plane
http://www.flyinggiants.com/forums/s...ad.php?t=54048

Taz_Hobbies

My Feedback: (15)

Hey that is a great thread, thanks for it.

I decided on the firewall issue. I am going to add a 1/4" firewall doubler which will allow it to be super strong even with the center hogged out for the carb and it also allows me to remove the 1/4" spacer on the standoffs for a more stable mounting platform. I will of course gusset it and glass it.

As you can see, there is quite a bit hogged out for the carb. I think the additional 1/4" ply laminated in front of the OEM firewall should do the trick.

Taz_Hobbies

My Feedback: (15)

I also changed out the stock hinge points for Robarts and I worked on getting the hinge line as tight as possible with no binding. I am pretty happy with the results of a little time working the air gap.

kerwin50

O buddy your looking good. Your going to love this plane. I hope the DLA works out for you.

speedracerntrixie

My Feedback: (29)

I wouldn't be too worried about the firewall. The material in the center really does nothing but go along for the ride. When the engine is bolted on it becomes a structural addition. You may want to consider pinning the firewall and if the motor box does not have any tri stock on the inside you will want to add some. Because the wood has already been sealed with god knows what, glassing will be of little value because unless you are sanding the finish off you are glassing onto the finish and not bare wood. Being a small airplane adding weight would be something I would consider carefully.

kerwin50

Well speed speaking from experience I didn't glass my motor box in the beginning and after a 1/2 gallon of fuel it started coming apart.
Several others have had this same problem with this plane as well.
The motor box is not sealed and the fiberglassing really did help.

Even with the addition glassing and beefing up the landing gear area my plane came out to 10lbs 4 ozs which gave it a wing loading of 23 ozs per ft. Thats quite lite.
She's a real 3 d machine and makes some one like me even look good.
Knifes edges are effortlessly, Flatspins are floaty and slow while Knife edge spins will blow your mind.