LGM Graphix

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Well, after approximately 4 weekends here is what I have so far.
Trim Aircraft Spectre. It is fitted with a RAM750, BVM wheels and brakes, Spring air retracts, JR radio equipment, a tail pipe is coming from RTI, and a custom tank from Jet Tech. I managed to get 2 liters in there LOL!!!!!

It's actually a pretty quick kit to build considering all you get is fiberglass fuse and foam cores. A lot of the ply parts are precut, but I changed the gear mounts as I thought their system was heavy and not very strong. I managed to screw up my canopy though so I'm on the hunt for a new canopy (I hate those things LOL!!!)

Anyway, not sure yet what the finish will be on it, but it will be something cool, and visible!!!!!!

Here's a few pics so far

SJN

Looks great already :-)

are the wings sheeted, or do you have to apply the skin yourself?

SJ.

CRAZYFLYERuk

are you really putting a ram750 in it cus trim say it does 189 mph with a ramtec/os91
im putting the pst j600 in mine & i think that may be i bit over in power

ps does the ama have a 1 : 1 t/w ratio on turbine models

andy

LGM Graphix

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I really am putting a RAM750 in it. I considered a PST, but I thought about it, and I talked with Dean Wichman about it, and beyond not wanting to buy another engine, I am flying at 3200ft above sea level, off of a grass strip, and didn't think that a PST would do any better for me than a fan. I don't have to run 18 pounds of thrust of course. I am in Canada, so the only limit's I have are a top speed of 250mph according to our MAAC code. There is no power to weight ratio here like the .9 : 1 that the AMA has. However, I won't be running it at full power anyway, I don't want it to be stupid, but I had the RAM, and the truth is, the air start ram isn't much heavier if any heavier than an auto start PST with the extra batteries and stuff anyway.

LGM Graphix

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You have to do it all, the only thing done for you in this kit is the fan mounts are installed (which were crooked incidentally, thankfully I had to modify them for the turbine mounts anyway). But you have to sheet everything (and they don't even include the balsa) cap everything, fit everything etc. Their machine cut parts have been pretty good, requiring only very little sanding to fit, especially nice was the precut hatch rails and formers, it made cutting out the hatch very simple, actually this hatch was easier to deal with than most jets I've built with a molded hatch.

CRAZYFLYERuk

i have the j600r which is 1kg thurst more than the standard 600

we dont have the t/w ratio in the uk so i have no prob there

have springair retracts /trim brakes im putting 1 servo for flaps & 1 on each elv + ale dont like the look of the rods that came with the kit would be ok for d/f not turbine

andy

wiking

Look at this baby it has SimJet 3000!!
MACH 0,5-6 at least Owner,Builder,Pilot is Lars Palm Sweden.
i have more pic,s of the mod,Spectre.

Regards
P.Anderson

LGM Graphix

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I really considered that too, but I got looking at the stabs, and the bearing blocks they used I did not think were up to the task of supporting the stabs without a rod going directly across and tied into one crank as an integral unit. I will be using just a single servo with their crank system, on that crank that they have built, it would require over 6000 pounds of force in shear loads to break it and I am not concerned about that. As for the ailerons, I have also decided to use one servo, I put the torque rods in a vice to see how much they flexed, and they took so much force to move, that again, I don't feel they are innappropriate for a turbine. The ones in my kit are 3/16" solid rod (I'm sure they are the same in all kits) and the weakest point is going to be the links and servo horn as is usual. I am using heavy duty 4-40 ball links and aluminum servo arms in all of them.
One of the reasons I feel that they will be perfectly acceptable is that I consider airplanes like my Kangaroo, which although it uses one servo per surface, we are relying on those composite cicuirt board material horns, and they haven't failed, but that is a far weaker system than what is on the Spectre.
The other reason is, when the jet is moving at a high speed, the amount of throw is very little. I have built all my surfaces with hidden gaps to help alleviate flutter, and in airflow, with surfaces at neutral, there is little load on any servo's. I may run 2 servo's together on the stab for extra power, but I don't think it's needed either. I don't plan on running a full 18 pounds thrust out of my 750 and doing 250 with it. But when you look at the stab rods, and the crank that they use, it is a very beefy system. I dont' really have any concerns with it's strength, and with a full flying stab like this, if one side fails, having 2 servo's isn't going to save your airplane with only one stab half working. The big trick on that style of stab is making sure it's balanced well, and making sure there is no slop.

LGM Graphix

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wiking,
Could you email me pics of that modded spectre? especially if you have any of the turbine installation and tailpipe setup? Also, does that one have a bigger wing?


thanks
Jeremy
[email protected]

Hawkflyer

That looks great.

I have the DF version it flies great. The only modification I would do if I was to build another
are
Make the engine hatch bigger
Install some sort of former in the rear fuesalage, as on mine and others I have seen if you grab the fin at the top you can flex it a fair bit each way. I think it is actualy the fuesalage that twists.
It seems ok for DF but if you make the aircraft a lot heavier it might cause a problem.

How much fuel can you fit in the fuesalage ? Do you use the same inlet ducts or do you make them smaller to fit the fuel tanks in?
Are you putting the elevator servo as per the DF version? If so will the heat effect it?

It is a shame Trim don't make a turbine version.

wiking

Hi there!
Here is some info about the Spectre.

The wing are extended about 4 inches on each side with a fiberglass molded part.
The stab is molded and the vertical fins under the fuse are also molded.
Fuel cells are molded and the total amount of Jet A1 is 2.7 liters incl the hopper tank.

Lars dont have any engine hatch on the Spectre because it makes the fuse stronger
he have all the nipples and fuelings under the canopy.

The fin has a lot of carbon fiber just to make it.

Inlet system is smaller and its full bypass.
The heat does not effect the elevator servo beucase it is isolated from the warm parts.

Jeremy i will send you pics of the Spectre but first i must ask Lars if its ok.


Best Regards
Per Anderson

wiking

BMT

Hi Jeremy,
I have flown my own Spectre in D/F format fitted with a BMT80 (19lbs thrust) some years ago. I did however strengthen the bottom wing skin with kevlar right past the wheel wells. The Spectre has a high wing loading so anything less than a good landing cracked my wing from wheel well to LE. Glass would not hold. I used the standard torque rods on flaps/ail and a high power servo for the stab with a 2" pushrod. Heat is not a problem if you use a double walled pipe. My engine was mounted very far back with 2l of fuel just about on the CG. The spectre is a joy to fly and can be landed at almost walking pace if you keep the nose up and some throttle up.
Andre Baird[img][/img]

LGM Graphix

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Wow, looks like Lars has done some major mods to it! Thank you for the pictures!

Andre',
My engine is mounted fairly close to the CG with the tanks in between the inlets, so unfortunately I will be taking off nose heavy. I am very glad to hear you say it can be landed slowly though as previous to your comment I had heard it was a very fast landing airplane. I was told to add a speed brake but I'm not sure where I would do that, behind the wing and you hit it on nose high landings, in front of the wing and you have issues with actuation and strength IMO. I will be using a double wall pipe, with the same servo idea's you mentioned. I am also adding a former to the rear of the fuse with a spar to support the fin. I'm glad to hear about the landing gear cracking, although I have modified my mounts to be an integral piece, not the 2 rails like the plans use, I can see those torquing very badly which is why I built mine the way that I did. I think I'll be ok with the wing.
By the way, I think your Spectre has about the nicest scheme on it that I've seen on any Spectre so far, it really flows nicely with the lines of the jet and the color choice is great!

BMT

Hi Jeremy,
I did not have any problems with the gear mounts really but the kevlar helped with the centre section and the weak area between the wheel wells and the LE and TE of the wing. The Spectre does land very fast unless you get it onto the "reverse power curve", meaning you do a landing circuit with ever increasing elevator and throttle until you have a good nose up attitude. Use as much flap as you can get, up to 80 deg. You are then able to do your final approach from a fair altitude trading elevator for speed if you feel your approach is to slow. the decent is the very steep but with a nose high attitude. The higher throttle level also translates into quicker throttle response when needed. One point of concern is do not overdo this on a windy day. The last few feet of boundary layer above the runway has a lower windspeed and you drop like a brick through it if you are to slow. To fix this you gain speed just before landing trading some height for speed and then flare the normal way. In fact this type of landing needs a tailskid as you land very nose high!
Thanks for the scheme compliment. I used auto 2 pack metallics with a clear coat and tons of elbow grease. I refinished the model but did not build it. I still have it but the wing with the D/F cutout evetually started to weaken.
The mods Lars did will give a lot of speed as the D/F intakes are like big airbrakes.
Cheers
Andre

wiking

Turbine Spectre parts for sale!

LGM Graphix

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oh dear, does that mean it's broken? or that he's still got the molds and making parts [sm=bananahead.gif]

Kaos1

Glad to hear how well the Spectre flys. I'm building one now. DF version, OS 91 w/ Dynamax fan. I have the wing about completed and saw in the instructions that the flaps are to be beveled 0.5mm on the top with 5mm on the bottom. Does this mean 0.5mm back from the leading edge of the flap? The torque rod is well down toward the bottom of the trailing edge of the wing. So I take it that there is a deep, narrow break between the flap and wing as seen from the top and a shallow wide break from the bottom?

This has been a slow project with little interpretational hang ups along the way and I'm getting anxious to get this bird in the air. It doesn't help that I can only squeeze out a few minutes hear and there to build.

Anyone with experience on the rudder effectiveness on the Spectre? I have heard varying opinions but not sure if they have come from experienced Spectre pilots.

Thanks for any advice!

Kaos1

BMT

Hi Kaos1,
Never used the rudder much except for takeoff and point/slow rolls. At turbine speed it seemed adequate to me at least. I used micro metal geared Hitec servo on the rudder.
I would say that in turbine or even D/F mode test flying and familirization is best done on a real long runway. That goes for most jets....
Andre

Minch

I too have a Spectre awaiting a turbine conversion, I got my conversion bits from trim, a stainless tail pipe and engine pod. All I will have to do intakes wise is make them a bit smaller. I am intending to put a Wren 54 in mine, I already have the engine but I am putting it in something else at present as the Spectre is going to be a long term project as I have an Avonds F15 to build next.

Just a few question on the Spectre, I was thinking of possibly using a one piece elevator rod or splitting it at the centre(so you have 2 equal lengths) and then putting a brass or similar sleeve over the rod so it is vertually the wide of the inner fuse. Anyone done it this way or has everyone stuck to Trim's D/F instructions method. If anyone has done it a different way could they explain.


Minch

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Minch,
I too considered using a single rod through the entire fuselage, but then you run into the problem of, how do assemble it all, and worse, what to do should you ever need to remove it? You could fasten it at each stab half with a bolt like a plug in wing tube, but you really don't have much thickness and I don't think I would want that shaft just sitting in the wood blocks they give you. If you were to make a fiberglass sleeve that it slid into tightly then it would possibly work ok. The problem with splitting it in the center, is that you still have 2 rods, only now you have no way to strongly connect them. Using a brass tube as support would not carry the strength that the big aluminum crank arm they supply has. You would then need to use a crank on both sides of the stab with 2 servo's (not that this is a bad idea) as you cant' put a single crank in the center. I think that their system is a decent system. I considered using 2 servo's for the stab, one on each half, but then though, in a full flying stab aircraft, if one half fails chances of survival are so slim anyway that I don't think it would be of much benefit. My stab will use the standard system, but I have to move my elevator servo. I have a double wall pipe built by RTI, but the outer pipe was made to fit the diameter of the tailpipe opening which puts it a little to close to the elevator servo and the arm hits it. So my plan is to move the elevator servo up into the engine bay and use a carbon fiber pushrod fully supported all the way back to the stab crank to acctuate it. I will be using a JR DS8611 servo which at 220oz of torque should be WAY more than enough. My choice of using a carbon fiber rod is simply due to the lack of change with temperature found in Carbon fiber so there shouldn't be any trim changes. I went around and around on this for a long time, and I thought about many different options, but it's amazing how strong a pushrod is inside of a sheath (golden rod style) when totally supported. I used the carbon fiber golden rods on the elevators of my exocet and they are rock solid. I will take some pictures of my elevator servo installation in the Spectre as I do it so you can see. The other thing I like is that my servo will be closer to the CG. Just a little less weight in the tail.

I used a DS168 wing servo in the fin for the rudder, and will be using Trim's standard aileron and flap system although I built a hidden hingeline into it. I used the standard inlets, but due to using the RAM750 that isn't a problem, they are actually smaller than what is on my exocet and my exocet works fantastic and the 18 pound thrust engines don't seem to be as susceptable to problems do to large inlet sizes.

Perhaps I'll get some work done on the stab today

Jeremy

wiking

I meant that you can order the option parts to convert your DF Spectre in to a Turbine Spectre!

Its simple you order and i make parts
Just tell me what you need

P.Anderson


p,s
Jeremy i have take the Digi Cam and visit Lars.
I send you pics after the week-end.

If there are any interest i can upload some pics on the Rc Universe

LGM Graphix

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Man, if you weren't overseas where shipping would be so high I'd order a canopy from you, I screwed mine up so now I have to make one

wiking

Aaahaaa you want a canopy made of carbon fiber!
I can make one for you if you want.

LGM Graphix

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sent you an email