robson63pilot

I would show the progress as I go through the REACTION build. The parts fit is very perfect, and that this is truly a joy to build

Michael T Ward

Hello im looking at buying a R54 as my first jet infact i have decided to get one im going to put a wren 75 on it but my club has two rules i have to follow. 1 - a jet must have a kevlar fuel cell2 - must have majority of wheels with brakes so i have to put brakes on the two main wheels. I was also looking at a set of trailing link struts so i protected from the roughness of the grass strip and the ocaional rough landing so i was wondering will this undercarage combo fit http://dreamworksrc.com/catalog/reac...xe-p-1311.html
And a frend gave me on of these http://dreamworksrc.com/catalog/star...em-p-2491.htmland said it would be fine to go on the side of the plane just above the wing and i was wondering if i put it there would it cuse problems with fuel coming out going along the side because of wind and going in the front of the engine so i was thinking the best place for it would be on the bottom just i front of the wing that way there is no risk of feul being injested in the front of the turbine wich i beleve would be bad please correct me if im wrong.

So if all you guys could help that would be great.

speedbrake

Michael,
You didn't mention which version of the R54 you were buying. The ARF version comes with composite tanks and has a retract system available with brakes from PST for $650. The balsa kit has a retract system available from BTE. Robart has struts and brakes available for that system. There are composite tanks available for the balsa kit. Sorry I don't have a company name for you...read through the R54 thread and you will find one.

The Dreamworks retracts look really nice. They are designed for the ARF kit. I'm sure they would fit the balsa kit as well. The fuel fitting looks really cool, however I plumbed both the ARF and balsa kits per directions with no problems. The fuel vent on both exit the bottom of the fuselage just in front of the wing.

Good luck,
Keith

Michael T Ward

Thanks for that. I am going to get the balsa kit one i dont have that much biulding exsperence but everyone raves about the kit so i want to try building a plane and my father can help where i lack he has a lot of exsperence with balsa planes he has 25 planes every sigle one balsa and all constructed by him. And i have already found a kevlar fuel cell - http://dreamworksrc.com/catalog/reac...2oz-p-925.htmli saw other people using them in this thread. oh and one other reason i went with the kit is the arf is much bigger and the kit is already pretty big and i want to do my own paint job.

BruceTharpe

My Feedback: (1)

Michael, I have to correct my friend Keith on one thing. The Pro-Links retract package from Dreamworks is for the ARF Reaction. They are not a drop-in fit for the R54 wood kit. The ARF struts are substantially longer than the wire struts normally used in the wood kit. I don't think the Pro-Links can be modified to fit the kit, but I suppose the kit could be modified to fit the Pro-Links. I don't have any instructions or guidance on how to do that, so you would be doing your own engineering if you modify the kit design. Just want you know the facts before jumping in with the Pro-Links...

bobparks2

My Feedback: (1)

Looks like you already found the JetTech Kevlar fuel tank made for the balsa R54. I have one and its a nice tank. I measured the actual capacity a while ago, and its posted somewhere in this thread. Its quite close to the claimed size. OTOH, it does not have as much extra capacity as you would think compared to the stock plastic tank, because the DuBro 50 oz is actually quite a bit larger than claimed, near 60 oz as I recall.

For the balsa Reaction, it probably does not need the Kevlar tank to be safe in a crash. The fuel tank is well protected in the fuselage, and there is a lot of structure between tank and engine. The "fireball" crashes that happen sometimes with jets are due to the engine ingesting liquid kerosene from a ruptured tank, while the engine is still running. If the engine goes out even 1 second before the fuel hits it, no fireball. So, compare the R54 setup with all those jets that put a tank immediately in front of the engine with nothing in between and you will see that its just fundamentally a LOT safer. Also, the balsa R54 has that long, all wood nose. Thats going to absorb a lot of energy in a crash as it comes apart. Way more than most fiberglass jet fuselages, which just shatter. That also protects the tank. (does anyone here know of any high speed, nose first R54 crashes and what happened?)

So, the R54 with plastic tank is probably WAY safer than almost all the other jets out there with Kevlar tanks. But, you have a good, available option with the JetTech tank, and it gives you about a minute extra flying time anyway, so just go with that.


Interesting rule for a grass strip.. you probably dont really need brakes at all. Bruce's suggested electric brake works well, but I fly from a paved runway and want a bit stronger brakes. I went to some conventional Jet wheels with pneumatic brakes. I dont have the packaging anymore but think they are Trim brand.

The trailing link will help on the grass roughness, but IMHO, ALL of the sprung struts for RC jets that I have seen have too soft springs to really help in hard landings. They bottom out at less than 2g's and you are then worse than having wire struts.

I just bought one of those last week. Nice unit! No worry about fuel getting sucked into the engine, since once the engine is running, the fuel is going the other way and air is being sucked into the vent pretty rapidly. I have not decided between a side mount and a bottom mount yet. Side is easier access and you are less likely to forget and leave the plug in place, but if its on the bottom, any drips dont land on the plane, so its a bit neater. I will most likely put it on the side.

Bob

jetflyr

I just bought one of those last week. Nice unit! No worry about fuel getting sucked into the engine, since once the engine is running, the fuel is going the other way and air is being sucked into the vent pretty rapidly. I have not decided between a side mount and a bottom mount yet. Side is easier access and you are less likely to forget and leave the plug in place, but if its on the bottom, any drips dont land on the plane, so its a bit neater. I will most likely put it on the side.

Bob
[/quote]

Lately, I've found that just in front of the wing root, slightly angled down works very well. Easy to see, easy to attach/detach and hard to forget. Drips (and there are some when disconnecting) fall downward, and since it is not on the bottom, things don't get banged/jammed when sitting the plane on its belly.
Greg

bobparks2

My Feedback: (1)

A bit hard to angle it on the slab sides of the Reaction, but that sounds good to me. On the side, near the bottom, just in front of that bulkhead with the holes for the air tanks.

Thanks!

Got a bit of progress on it this weekend. Boring stuff like making wiring harnesses, but now that is done, its time for final assembly on the wing.

Bob

Michael T Ward

Can somone provide me with the mesurements for the standard wire struts so i can have a look around for some shorter struts of some as close to the right length as possible

BruceTharpe

My Feedback: (1)

The kit R54 struts were kept relatively short because they are wire. As mentioned in many posts, the wire struts do a fine job on grass and can handle more abuse than you might expect. To be honest, I haven't spent any time researching possible trailing link replacements - maybe there's something out there now that will come close. This pic should help with dimensions...

PaulD

My Feedback: (39)

I would follow Bruce's advice and just go with wire struts and Robart retracts - works well and is more cost effective. If you want the brakes, buy a set of intarico wheels/brakes and stick them on. (They're made in Aus anyways airen't they?) If you do go with the Dreamworks set - get ahold of them first and tell them the application - they should be able to size up a set with the proper strut lengths. I built a Reaction for a budy last year and he had purchased JEt A-1 gear for it but with the correct lengths. It seemed to work really well and the springs were not too soft. I believe Dreamworks also has options for stiffer springs - I would buy both sets and experiment to see what works best for you.

The Jet-Tech Kevlar tank is overkill IMO but if your club says you need it then you don't really have any other options.

Have fun building it - they're a great flying airframe. Don't be afraid to put at least an 18 lb turbine on it - they respond really well to the extra thrust.

PaulD

JustFlyIt

Have to admit...I added the Prolink to my Reaction because I just plain liked their looks and the "knee joint" seemed like a good idea. I know that there was nothing wrong with the wire struts. Had to make a few changes for the wheel well but nothing major or difficult.

Also, I have the brakes too. I hope to fly my Reaction at Jets Over the Heartland in June and I am pretty sure that they require "traditional" brakes.

I have a few things left on my Reaction to finish and hopefully its maiden flight is mid-April. Definitely will post a video.

My Reaction: http://www.rcuniverse.com/forum/fb.asp?m=10899776


Don

robson63pilot

Building the wing completed
And small changes the retracts Behotec C-36/2

Bruce ,thank you for all the answers to my questions

JohnVH

My Feedback: (38)

P70 guys, any tips, also, can anyone get me some pics under the hatches?

Thanks!

Ayrtonsenna

My Feedback: (1)

P70 + Reaction= sold mine back awhile ago, In my eyes, it was the best combo.. good luck

PaulD

My Feedback: (39)

John,

I managed to squeeze a P70 under the airframe. U need to use spacers (plywood) approx 3/8 thick between the turbine mount that comes with the plane and the Jetcat mount so the turbine will fit into the mount. I also notched out the boattail quite a bit for the starter to move the turbine as far forward as possible.

PaulD

JohnVH

My Feedback: (38)

I have the P70 mounting kit from Bruce, and the tail is notched, Im more looking into the under the hatch layout, trying to find my manual for recommended setup but cant find it. I have it around here somewhere....

I have the wing ready to go, servo's in the fuse, just figuring out the details then pull the P70 from my BVM Fury..

BruceTharpe

My Feedback: (1)

Another good time to refer to my "Index to the Definitive R54 Forum Thread" here:

http://www.btemodels.com/r54threadindex.html

Scroll down to the "Radio Systems, Servos, Batteries, Antennas" category for a peek under the hood of many R54s. I know maxvertical and ayrtonsenna used P70s in theirs...

JohnVH

My Feedback: (38)

awesome, thanks Bruce, forgot about that!

picard1

My Feedback: (2)

John,
I can shoot and post some under hatch pics tonight.

KC36330

P-70 is a great combo!!

JohnVH

My Feedback: (38)

is cg anything to worry about? Keep everything forward as possible?

KC, notice much CG shift with that fuel tank up front?

bobparks2

My Feedback: (1)

Putting 2.4 GHz antennas right next to a carbon fiber plate would seem to be not a good idea.

If nothing else, those antennas are fully shadowed to any signal coming up from the bottom, and you will get some destructive interference reflections with signal from the top.

Actually, why even use carbon fiber for a mounting plate? Other than the bling factor, I sure dont see any advantages over lite ply, and it sure has a lot of disadvantages. (hard to cut, expensive, RF opaque and reflective, and if its not a sandwich panel, minimal vibration damping)

Bob

KC36330

it does have some shift but it's not anything drastic and well worth the extra flight time.

FYI it's simulated carbon it's been taken to over 3000' AGL, never lost a single frame on any flight.

JohnVH

My Feedback: (38)

my old 3.3m comp arf yak was laced in carbon throughout, never had any range issues with it, but it was on 72mhz. Ill be putting 2.4 JR in this things.

Im suprised you could even see it at 2000', you even sure it was that high? Ive flown over an rc field at 1500' before and the planes flying were specs below me..