parkpilot01

I ordered a Hangar 9 Pulse XT 40, and now it's waiting patiently under the christmas tree [:@]. I'm planning on building it strong, even if it turns out a little heavy. I'm going to reinforce the firewall, but i dont know how? Any ideas will be much appreciated.

cold_reboot

My Feedback: (20)

Fiberglass Cloth and Epoxy (do this on the inside of the fuselage btw)

w8ye

My Feedback: (16)

Use tri-stock in the corners and fiberglass the tank compartment.

I change the landing gear to bolt on with nylon wing bolts then I reinforce the LG mount.

cold_reboot

My Feedback: (20)

All of what w8ye said, I was assuming the Hanger 9 would have the tri stock reinforcement already there. I've never had a Hangar 9 that I paid much attention to (I had a Hanger 9 P40 but sold it without ever opening the box...I'd starting kit building shortly after acquiring it). The one ARF I've had for a while (VQ 109E) and still have didn't have any tri stock reinforcement. It's never been flown. I plan on stripping the shelf paper covering and recovering the whole thing. While I'm at it I'm also going to cut a new firewall from aircraft ply since the Vietnamese firewall seems extremely flimsy and brittle.

manks7477

Build it as per the plans. These planes are well designed and are engineered to be strong enough.

Build your plane to perform in the air, not to survive a crash. My experience is that if your hit hard enough on the nose wheel to break loose a firewall, the break likely absorbed part of the impact that would have done a lot more damage to the airframe. I would much rather have to repair a fire wall that popped out than repair a fuse that snapped.

As for bolt down wings, if you are an experienced flyer, then yes, if you are learning go with the elastic bands, they are much more forgiving when you crash - and you will.

If you do pop the firewall out, or it becomes loose, use the triangle stock and 30 minute Epoxy, that will help shore up the repair.

cloudwalker

Hi park pilot, You got all good advice off the guys, but I,m sure they wont mind if I chip in with what I do. As long as you dont add to much weight im all in favour of strong fire wall. I start by cutting a 3.16 th birch fire wall, this fits to back of the one on your plane and then your angle stock . Ive never had one come apart yet. Athe moment i have this arrangement supporting a 20cc gasser.CHEERS if you cant walk on water learn to swim[sm=drowning.gif]

Bob Mitchell

The firewall on my Alpha 60 separated 5 minutes into it's maiden flight. H9 replaced the plane and on the second one I pinned the firewall using either 1/8th or 3/16's dowel.

scratchonly

I agree with 7477; most kits have adequate firewall mounting. You may lose your firewall if you build too heavy, this happening due to severe contact with the ground![&o][&o][&o]

cloudwalker

HI manks I think your advice to parkflyer was sound and well put over. I was just thinking of one kit maker here in the british isles (scotland). He stated on the plan that I should stick the fire wall with super glue then put a piece of glass cloth on with super glue. IM glad I didnt follow the instrucions as i saw on one of these pages that somone had used the advice , and the engine had came away in flight lucky for him the cowl retained the engine. I suppose its important not to go to strong and not to weak. regards Bill if you cant walk on water learn to swim.[sm=drowning.gif]

bigtim

My Feedback: (13)

you probably should have posted a link http://www.horizonhobby.com/Products...ProdID=HAN4100 so people were clear on the plane, I had to look it up myself to see it was a low wing sport model.

what I would do is check the firewall for triangle stock in the corners, if there is some which most H-9 planes come with now, because of repeated complaints of firewalls ripping out don't trip just assemble it,and have some fun.

if your worried about it, then warm some epoxy,by heating up some water and setting the bottles in it with the tops removed,just like pancake syrup,warming the 2 parts separatly will allow the epoxy to thin and spread out easaly.

it doesn't need to be hot just warm, it will be watery, the heat will make the epoxy kick faster so just mix a little at a time, and with a cheap brush coat the tank area with the epoxy, it will provide a fuel proof tank compartment in case you get a leak in your fuel tank and will strenthen the joints where the firewall joins the fuse other than that your just adding weight which for that plane is no help,you don't need alot just enough to wet the wood, it will provide strength and fuel proofing without adding alot of weight.

if your going to strenthen any area I would look at the landing gear attachment point being a tail dragger thats a area that can be a weak point,and on the pulse it doesnt look all that strong from the photos on Horizons site just take a look if it looks sound then don't bother with it .

finally when your coating the tank and LG areas, before you apply the epoxy, install the blind nuts for the engine mount, and landing gear first , just dip the bolts in Vasaline/petrolium jelly to prevent the epoxy from sticking.
screw them into the blind nuts to protect the threads fom getting clogged up with glue,not too deep, just enough to protect the threads, the epoxy will hold the blind nuts in place,if you coat the wood before you install the blind nuts the points won't be able to penetrate the wood to hold in place when your ready to mount your engine etc....

when the glue is dry just back the nuts out wipe any exess Vasoline off and assemble away.

cold_reboot

My Feedback: (20)

I don't know about the Pulse, but the Hangar 9 warbirds were/are known for firewall separations. Hangar 9 may have fixed this by adding tri stock reinforcement, you'll just have to look inside the fuselage when you open it up. I usually reinforce the landing gear area with a few pieces of tri-stock as well

bigtim

My Feedback: (13)

the 2 warbirds from H-9 that I have, P-51 and P-40, both have tri-stock at the firewall/fuselage joint, they seem to have listened/got sick of replacing planes that have had firewall separation.
when I got mine a couple of years ago, the correction was allready made, after reading alot of the complaints about this issue in the forums it was the first thing I checked when I recieved the airframe before assembling them.

Hossfly

Good idea PP01. Adding a few ounces structural weight to most of these ARFs doesn't hurt anything. I have built powered models since the late '40s. I have suffered many structural failures especially during the first 10 years when there was NO epoxy, NO CA, and little fiber glass.
For those that say ARF structure is good enough, well I like to know when those guys are flying at a field that I am at, so I will be more alert when within 100 feet of where they start up.
I have been witness to a number of engines departing company with airframes. To note was some 4 years ago a very highly experienced club member was flying an ARF with an oversized engine, a G-38 in a .90 airframe. After a couple flights, he was starting up again and decided to tach from the front. About that time that G-38 wanted to fly so much, it left the airplane sitting and took half a thumb and half each of two fingers along for the joy ride. [X(]
Later I looked at the firewall and mounting area and I would not have been flying that machine as it was structured with a low powered .40 much less a G-38 vibrator.
In the last 5 years I have seen a half dozen engines, from .40 to 4 cu. ins., depart the ARF machine in the air or on T.O. roll, and since I really don't fly much anymore, lord only knows how many I have missed.

I well reinforce my firewall areas. Good plywood doublers, thick ply firewalls, triangle stock, epoxy and medium FG inside the fuse., and even to adding 90* metal around the firewall edges, bolted to the firewall and doubler areas, absolutely, for gas burners. My GP "Little Toni", first with D-Jett .90, now just a sporster with a ST .90, 4 years going, had a very weak front end, which I did not redo adequately until after about 10 flights I discovered a problem. I had to go into it and make major revisions. Still going strong.

BTW, BigTim told you about warm epoxy. Here is the easy way. Mix it up, plop a big ball of it in the area to be applied, use your monokote gun or a hairdryer and warm it up. You can make it gin-thin, brush it around, and it will run into every crack and crevice, plus soak well into any cloth. Quick and easy but werar safety glasses if as messy as I am.

Most of my airplanes are built-up. ARFs however are NOT in my opinion well engineered at all. Mostly they are JUNK!

IMO, again, YOU are a very wise person for assuring that your engine will be kept in its place.

Best of luck to you.

496xl

Hossfly,
Sorry you feel or experienced ARF's that way in your life, myself have flown them
for over 12 years and never have been bitten like you have. ARF's are as good
as the person that puts it together,period.Just like a kit,like you said...beef it up,
Still learning,
Perry

pdm52956

My Feedback: (1)

I have the XT 40 and love the plane. Mine is loaded with a 46AX and it's a bit nose heavy. You'll most likely need a touch of weight to get to the correct CG, and you'll want it to be there. Expecially if it's your first low wing or tail dragger, or both. If I remember correctly, 2.75" is CG center. Put it there and you'll love the way it flies. You can adjust as you see fit after you trim things out and find out how it flies for you.

As for the fire wall, I can't remember (I claim old age) if it's beefed up with tri stock or not but regardless, I did coat the fire wall area with some thinned epoxy. I didn't make it too thick of a coat, just enough to provide some fuel proofing. Since the plane is slighty nose heavy to begin with, I didn't want to add too much weight up front. I've also gone to a 7.4 lipo with a 5.6 voltage regulator for the rx battery. Saved a little weight over the Nimh pack. None the less, I've not had any problems with the fire wall strength. I check it everytime I fly and nothings come loose yet.

I've not touched the main gear. I've read time after time about it being a weak spot, and it might very well be, but I've not had any bad experiences with it. I've had some bouncy landings learning with this plane since it is my first low wing tail dragger, and the plane comes in pretty hot compared to the trainer I have, but maybe I've just been lucky. It wouldn't hurt to reinforce it, but that's your choice.

Our field has a rather large hill in the distance off one end of the runway, and I've found that the plane can get lost in the background on approach. I took some black covering and added some "leading edge boots" to the wings and that seemed to help with approach orientation. I don't know, it helped me anyway.

You'll enjoy the plane. I haven't heard of anyone yet that hasn't. Fly it fast, fly it slow, just fly it. It likes that! Hope I've been of some assistance.

Paul

bkdavy

My Feedback: (1)

Reinforcing a firewall without adding significant weight is easy if you think about it. Most people like to add Tri-stock behind the firewall. My personal view is that this is not as effective as the two methods I use.

The easiest and lightest is to simply drill three holes through each side of the side fuselage formers into the firewall. the holes shoul not be greater than 1/2 the thickness of the firewall (1/8" holes for a 1/4" firewall). Then put toothpicks or dowels into the holes with 30 minute epoxy. If the fit is a alittle loose on the pins, use gorilla glue. If the firewall is only 1/8" ply, you can add small 1/4" ply blocks behind the fire wall, and then pin into those blocks from the side and the front. The key is to get as much interlocking structure as possible without adding a lot of wood.

If the plane isn't covered (kit, not ARF) the second method is to use light (.5 or .75 oz) fiberglass cloth with finishing resin. Wrap the fiberglass on the OUTSIDE of the corners of the firewall and the fuselage sides. This will ensure the fiberglass is loaded such as to resist the firewall pulling away under load. Putting fiberglass on the inside is less effective. As long as you use light cloth and finishing resin, you'll never notice it under the covering, at it will add a lot of strength. One layer is sufficient, but you can add two without visible effect. After the resin has cured, add a second coat of resin, then sand after its cured to feather it into the fuselage sides.

Brad

flyinrog

My Feedback: (1)

What he said, then slather a tablespoon of mixed up epoxy on the front and back of the firewall...Rog

parkpilot01

Wow, thanks for all the help you guys have come up with. I'm gonna go ahead and reinforce the landing gear with some tri stock and epoxy when i get the plane, because I fly from quite a rough grass runway, and ive seen many taildraggers lose their main gear on there.With regards to the firewall, I'll check whether it already has tri stock behind it, and if not i'll coat it with some epoxy. I would beef it up some more, but I will be putting a 46AX in it, and with pdm52956 saying its nose heavy anyway, I don't want to make it worse.

pdm52956

My Feedback: (1)

Oh you wouldn't do much damage with the weight if you reinforce the fire wall. There isn't a lot of room to get to the aft side of the fire wall anyway, and you'll see that the blind nuts for the engine mount will limit the size of the tri stock. When I coated the forward side of the fire wall, I got as much of the aft side epoxy coated as well. I'm figuring that probably helped with the strength......at least a little.

As for the nose heavy condition, mine did run nose heavy with the 46AX and I had to add a little weight to the tail, but I don't think it was outside the forward CG limit before I added the weight. The first time I flew the plane, I didn't have any tail weight added but when I brought the CG to the center of the range, what a difference in the flight characteristics! I ran out of elevator on landing without the weight, use much less elevator after the weight was added.

As for the gear, you might consider going to nylon bolts to mount it if you'll be flying off grass. They might shear off on a less than perfect landing before the gear block was to rip out. I don't fly off grass, so I'm not sure if that would help save the gear or not. I have landed long many times when I first started flying this plane and ran out of runway onto grass. Didn't have any issues there, but then that's not the same as a full grass landing now is it. Anyway.......just my thoughts.

You'll love the plane. Enjoy it.

Paul

496xl

Hi Hoss,
Sorry you feel that way about ARF's, I've flown my beefed up ARF's for over 15 years,
never any problems,I tried to break them,did'nt happen. So long story short.....you must
have a sour taste in your mouth that need not be said in this Forum. ARF's are as good
as the builder........................Just like any kit. Please do not discourage our readers.

P.S. when I say beefed up ARF's, meaning nothing to do with the airframe. And if I ever visit
your field, I will do a low fly buy across your head with my ARF. You can trust my bird.

Beeing nice,
496xl

Jetdesign

My Feedback: (8)

My plane just came with tri stock around all four sides of the firewall - inside AND out! Doused them ALL with a good bit of 30min epoxy. Four more pieces ran from the firewall down the length of the plane to the main cabin; those got epoxied as well. Mixed some alcohol in the remaining epoxy and fuel proofed the whole inside and outside of engine compartment. I think if someone got sneaky and put a bomb in my plane, a pile of splinters would fall from the sky, just behind the perfectly in-tact engine compartment of my plane

It's now SO solid; feels nice

w8ye

My Feedback: (16)

That's the way to do it.

Around the engine and tank compartments I try to make sure the thinned epoxy flows into all those cracks and crannies.

Hossfly

Since this is YOUR second such post relating to ARFs as good as the builder, and specifically addressed to me, I gather you are trolling for some kind of altercation.
IMO, these beginners need some encouragement on proper airframe care. They don't get it from these ARFs that dominate the market. If they do get discouraged when someone advises them the safe route to take, then what the "L" do you expect of them when they are missing fingers, hand, etc. Again, IMO, anyone too meek to address such should stick to badminton and gardening.

Your beefing up having nothing to do with airframe means nothing to me. As far as your low pass over my head, have at it but please be advised that such a pass is limited one to a customer. That, SIR, is a promise! [>:] You will be very eager to restrain any desire to make a second one. [sm=49_49.gif]

Hossfly

Guess you noticed that your second post received the answer that you were trolling for, and those two posts did not stay long. HA!

As for ARF structural integrity, a very interesting item is in the Dec. '08 RC Report. 62" w/span TWIN ELECTRIC E-Flite "Dueces-Wild" Review. THIRD FLIGHT, BOTH FIREWALLS SEPARATED. 'nuff said!