The firewall cracking is usually not the problem. The lack of glue, pins, glass or tri stock allows them to come out of the plane. You said it seems there was no glue on the old firewall. How did you correct that? Did you pin the original firewall?

Flying freak,
please do not think i am picking on you as your success would make me happy. You have a good engine and there is no need for you looking for and not finding it out in the brush because it came out of the airframe. As so many here have stated it is a common problem for the firewall to come out of ARF Q-500 planes and Q-500 kits when they are not put together right. I can not see what you have done very well from the pics but gluing a piece of ply on the nose and not correcting the problems with the original firewall may not help you. There are several people in here responding to your questions that know more then me so lets make sure it is right before the maiden. DaveN and BobB, do I have a valid concern? If you two do not think so I will bow out.

Im pretty sure it helps because tis almost a second firewall and i KNOW this one has enoguh glue/glass were as the first one seemed very thin and thus has very little surface area but now having it all glued in there there is about 3 times the surface area for the epoxy to hold that in which should help a bunch and there was very little tristock on the insted (3 small peice that were about a half inch long each.)

I use spruce tri-stock to help lock in firewalls, and I don't think there is a better glue than Gorilla Glue for these retrofit jobs. GG never gets brittle and never lets go.

Ditto that - Gorilla Glue aka ProBond polyu and the like, totally rock for structural joints on porous materials, other than the bits that ooze out on the exterior. I love 'em. If you know how to use them they are also far superior to epoxy for skinning foam wings.

MJD

Mike,

I agree with your statement on the firewall.. I must have read you're original post incorrectly.. I though you referring to how the engine/engine mount was installed, not the firewal.. My bad..

When the Viper and Predator first came out, the firewalls were very poorly installed. It was fairly common to see them come loose on a rough landing. Thankfully, they have gotten better, but they are still not as good as they can be.

Gluing a 1/8" piece of aircraft ply to the nose, does help. It ties the four sides of the fuse to the nose and adds thickness to the firewall, which I believe is only 1/4" to begin with, that is a good start. Adding 1/4" triangle stock around all four inside corners is also very helpfull, unfortunately, some of the ARFs have poorly laid up glass on the inside that makes it difficult to get the tri stock to fit properly.

Another way of reinforcing this area is to mix a batch of 30 minute epoxy with chopped carbon Fiber, a little cab-o-sil, and some micro balloons and make fillets all around the inside corners of the firewall. To protect the mixture from getting in the blind nuts Wax or Crisco up a set of bolts and screw them into the blind nuts from the front.

Lastly, you can pin the fuse sides to the firewall with toothpicks or 1/8" dowel. Personally, I am not a big fan of doing this when all four sides of the fuse are balsa. It works much better if the top or bottom nose piece is ply, pinning to balsa is not nearly as effective.

I do most of my noses with Gorilla Glue also, works very well.

Here is a picture of what I'm talking about in regards to the CF nose reinforcement.

This is from DK's Hurrikane instructions off www.supertrc.com

I am not confused anymore. You are one of the guys I listen to when advise is needed.

Yep, I'm pretty good at giving advise but rarely do I practice what I preach

Another method for re-enforcing, [or to make repairs] is to take sawdust, pack it into the nooks and crannies and then drizzle some thin CA on it. First, all the hot glue that the Arf was gobbed & cobbed together with needs to be scraped away, because it seems to repel real glue. A nice sharp wood chisel works wonders to delete some of that GodawfulArfwerk.

WEll one flight on it today i can saftly say this plane will never fly again maybe il but another i ahve one question is the cg in the manual correct? it was sooo badly out of trim it was unflyable if i would ahve gained hight and elt go it would ahve done an outside loop it wanted to dive sooo bad anyways i guess its part of the fun right [] well im running out of planes and the working season is over so no more fun for me

....this is what I told you in post #2 of this thread. My plane was darned near uncontrollable too. []

expo was set to 35% that wasnt the issue its almost as if the incedence of somthgin was completly off it just wanted to dive and dive hard it would NOT fly hands off this is what led to problems on landing ....

....did you crash the plane ?

Yes it crashed because there i had to land with the plane still WAY out of trim and ran out of up ele

Don’t give up build another.

I built my own pylon racer not quiet legal as the fuse at the wing was out by 1/8 of and inch.

But built the std tail section.

Fitted a MVVS Q500 and Hatori pipe.

On the fourth flight the pipe detached from the manifold and damaged the throttle servo.

Had to fly wide-open and big circuits.

Then ten seconds later no control.

Plane flew off into sunset never to be found again.

From what everyone saw looks like the lose pipe must have smashed the insides to bits and plane went off on its own at about 150 mph.

I was gutted to say the leased looked for hours for the plane to no avail.

So just a story to make you feel a bit better at least you have all your parts.

Also, I have owned the Lanier Predator prior to designing my own and that flew well once set-up and had an amazing glide. The only problem was you loose aileron and rudder effectiveness fast as it slows down, so line them up for the landing zone and let it sink in from a fair way out.

And most of the pylons planes are a handful until you get it dialled in then turn left go fast. I love the way the turn so fast, first time went round the first pylon twice. It was cause for some ragging at the field.

André