I have just got down to putting together a GP Reactor Bipe. I was quite dissapointed when I looked at the fuse structure. The thing is essentially a 2mm ply frame with holes that have been sheeted over with balsa. There is almost no tristock anywhere, no stiffning balsa, nothing! Everything is just interlocking ply, even the bulkheads are not reinforced in place. Even the LG block is just a ply former. Its likely to break soon on our rough field and I will need to reinforce before I do anything else.

Now, I am planning to convert the fuse side into a box structure by gluing balsa strips (1/4"x1/4") on the inside to form a truss like structure and then sheeting over with balsa ply for additional strength to form a box frame. Te balsa strips will be applied in the direction in which force runs in the fuse in case of a hard landing i.e. going from the TE on the LG towards the next bulkhead. Then I will use tristock on all bulk heads. Will add birch blocks with the LG block and tristock the inside to hold it in place. Will also fibreglass the firewall from both sides. I believe all this wont add too much weight, will be using a FS110A anyway.

My question is

1) Is this a good way to go about strengthening?

2) Should I use CF instead of the 1/4" x 1/4" balsa strip or will it just punch through in a hard landing? Also, there is a step between the balsa frame and sheeting which I will need to fillup on the inside with some ply to provide the balsa strip more bearing area. Should I just add the ply under the balsa strip or fill up the entire bay with ply?

3) Anything else you suggest?

Ameyam

Anyone?

I have over 150 flights on my bipe with a DLE-20 in it and haven't had any problems with airframe. This plane is flown hard with giant rates and it is still intact. I did do some glass work on the firewall but thats it.

Steiny

If you are flying from a paved runway, that is the reason. Our rocky bumpy field will cause more damage sooner. I am thinling atleast re-ply the inside of the fuse, then tristock wherever I can reach and fibreglass the firewall

By the way, what servos did you use?

Ameyam

I have had 3 relatively minor incidents with mine: 1st was battery coming loose/loss of esc power. Plane glided in on its own onto the gear, but tore gear off. Rebuilt the landing gear plate with the pieces and added tristock.

Second was hovering and hitting LVC on esc; dropped from about 8' onto lower left wingtip, breaking wing and tearing out gear plate/lower wing dowel plate. Repaired again, adding more tristock and some 1/4" square stock alongside the 2 landing gear fuse bulkhead formers. I would think if you add some tristock to the bottom/sides of the gear plate area, you will be fine.

Just dorked it on a wingtip again, doing a low torque roll in the wind. Wind pushed me more than expected, and I hit on the lower left wingtip again. Broke my (new) lower wing again. Both times, the wing broke right at the middle wing strut mounts. Think I can fix the wing this time...

None of this abuse caused any real damage to the fuse or firewall, and I'm running 1700+W on a fairly large outrunner. Don't think you'll need to do much else to the fuse except beef up the LG area, though 'glassing the firewall wouldn't hurt.

Nope off grass and snow Ds-821's all around.

Old pic with Saito 91 Just not enough power!

Thats a given- the LG Block needs beefing up. I mad the same mistake on my previous (two) Reactor 46s where I didnt reinforce the LG block and it broke off many times. In that airplane the LG 'block' is inside the fuse, so it does a lot of damage when it rotates. Someone on the Reactor 46 thread suggested two things to prevent this- adding CF stock inside the LG block and replacing the LG

The Bipe shares a few of the 46's problems- firstly the LG block is just a ply former. Secondly, the LG is two piece. In a hard landing, the LG flexes outward and the ply simply breaks in the middle. Also, the LG tends to rotate, crushing the fuse components near its trailing edge. So, I am planning to add in the CF stock across the fuse to take the bending moment and then put in some (furniture) ply in the LG block and secure it in place with tristock to take the compressive stress and shock. Problem is the tristock has nothing to glue against as there will be a gap between it and the fuse side due to the balsa frame. So at the minimal, I will need to fill up that bay

Second thing that happens in a less than perfect landing- if you hit the wingtip, the fuse will break at the dowel and behind the wing TE. To avoid both, I will tristock and fibreglass these areas

Firewall needs to be fibreglassed to take the larger engine / possibility of a DLE20 later.

I will need to relocate the blind nuts, so am ordering 4mm blind nuts so that I have something standard to work with instead of 5/64 screws everywhere (you can only use allen keys for those)

I will be using larger 3" rubber (or foam, depending on the total weight) wheels and am getting CF landing gear from HK that is one piece.

Plus I will put tristock everywhere in the fuse I can reach

Doubt this will add too much weight. I am still to study the fuse properly, not enough time after work[]

Ameyam

So you KNOW that this plane Needs reinforcement....but yet you don't kow what to use or where to reinforce it??

It is GOOD that the wing breaks at the dowl....That way it will give, and not destroy you wing entirely if you crash...

I am just asking whether CF or wood. Also wanted to know whether there are any other critical problem areas. Guess I convinced myself though

Ameyam

Build to fly, not to crash lol. Almost any of the modern ARF's are built largely of lite ply, which is a bugger to repair. A little reinforcement beforehand would be a good idea, but I wouldn't get carried awayit won't fly as nice, the more weight you add. Mine is 7lb 5oz RTF with 3300mah 6S packs. Flies very nice at that weight.

I have a DLE-20 and abuse it terribly. Full power outside snaps, blenders, etc. Fly it harder than my Velox and I snapped the wing off that one last week. Stock. Except added music wire between the wheels to keep the prop from breaking when the gear spreads and a little extra bracing for the engine.

I have a slightly more difficult problem right now. I accidentally mounted the wing brace the wrong way round. In trying to correct this, I broke the brace. There is some damage to the fuse as well but I repaired that. Now, the brace isint available for purchase seperately, only with the fuse and since installing the brace is one of the later steps, I already have assembled many of the parts on to the fuselage. Thus there is no point in ordering a seperate fuselage (and in any case, they are out of stock right now). Wrote to GP requesting them to send me a replacement brace and told them I was willing to bear the costs for that but so far no response

Does the brace actually serve a structural purpose or should I simply mould it out of some high density polystyerene (the extruded variety which can be sanded)?

Ameyam

It is what holds the top wing on! I would not use anything other than stock parts. I always check mine for stability because, I too fly mine very hard. Some times I laught because it stays together, everybody looks at me funny when I'm done flying, thinking tha I was trying to break it. All I know is I giggle when I fly this plane!

Looking through the manual, the brace actually just supports the wing against the fuse.

If I understand correctly, in a bipe the top wing produces a lot of lift and if it were not properly supported, the top wing would just break in two or break off the fuse. In the real thing they actually use the wire bracing to tie the upper wing top the lower wing. This may appear to have a bit of slack on the ground but once in the air, the wire bracing tightens up as the top wing tugs on it.

Now coming back to the Reactor Bipe model, there is no 'screwing-in' the top wing to the brace. You just have two dowels in the top wing that go into slots in the wing brace when you assemble. There is no physical assembly between the two other that that. So, the brace is there for aligning, providing a route for the wiring and for supporting the wing- it acts entirely in compression and the real load is taken by the wing struts that you screw in both sides of the fuse into both top and bottom wing. So, technically I can use just a polustyerene block -they are good in compression as I would be using blocks used in rooftop insulation (capable of taking 750kpa if I am not mistaken)- they are samp;es provided by vendors and its called 'XPS'.

Now hold on a minute before the readers get any wrong ideas. I have another Reactor Bipe which is still in the box and it has the brace. I am looking to see if I can get someone to replicate it for me so I can use on this airplane. If I cant find a source, I can make in polystyerene and then fibreglass over the top. I just dont want to use the brace from the other model right now and pass the problem onto when I build that one

Ameyam

THERE IS A CENTER SCREW!!!! You need to poke a hole through covering to istall it Plese read instructions more carefully.

Steiny

There is a 6-32 or 8-32 screw and blind nut that hold the top wing to the fiberglass supportdon't forget it! If you can make a mold with the foam and then 'glass it, great. This center pylon or brace is HIGHLY functional, in my opinion. A chunk of foam ain't gonna cut it...

So where is some photos of this part you talk about? A picture is worth a thousand words. Hey....get some phots on these forums like the F**ing G***ts have!!!

I do declare

Thats the way I am talking about, though I didnt see the screw. Let me first try the fibreglass (or wood) replication route if someone has the expertise or time for it. It is at times like this that I wish I had a 3d printer-scanner or a cnc machine or atleast a pantograph. It would be so easy to replicate it with a dremel then!

captinjohn, the camera's not working now else I could have been the first to put one up. The broken brace is gone but I have the replacement brace (from the other kit) which I will post. I am taking the part to a couple of auto repair shops today to see if they can replicate it using their fibreglass kits. I have a 4mm blind nut (here only metric sizes are available) to use and I need to order some anyway locally for replacing those in the firewall and LG where I wont use the stock inch screws. Worst case would be an order for replacement fuselage but that too unlikely tight now

Ameyam

If you have access to fiberglass and epoxy then I would make s mold
Of the new one you have. You could then make a new brace when you get the time to do so.

You can then take the new one off the nib reactor, and replace it when ready.

If you type in the words. Mold fiberglass parts ect ..you should be Abe to do it...

Try this... http://www.youtube.com/watch?v=C9wdAZWh0OA Good Luck, Capt,n

Actually, I am thinking of just using this. Its 'fomular metric 50mm thick' made by Owens Corning. Its high density extruded polystyerene 48kg/cu.m and high compressive strength. Like I said, its used for overdeck (roof top) insulation and very often we just put equipment such as air handlers, cooling towers, piping, etc directly on it (when the PCC blocks for those equipments cannot be planned at the design stage. I am in the building services industry). As you can see, I already have the basic shape marked on it. I didnt go for the fancy curves of the original part, choosing to straightline everything. Will ofcourse make a airfoil shape later. In itself this material is hard and doesnt deform easily. To add to that I will apply atleast two coats of fibreglass cloth on top (will build the part slightly smaller than original and then add the cloth on top). Will then add in a couple of CF dowels or one hollow tube (for the wiring) for additional rigidity. For the screw, I will insert a block of birch and then tap in and use a nylon or MS screw as we used to do with wing bolts earlier. Think that should make it strong enough

Ameyam