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Models for the Wren 44 - AGAIN!

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Models for the Wren 44 - AGAIN!

Old 04-12-2015, 11:46 AM
  #26  
FlyEng
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Check out my A7 add. Its on RCU and RGC
Old 04-12-2015, 12:25 PM
  #27  
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I was thinking about this 90mm T -33 from blackhorse
http://blackhorsemodel.com.vn/?product=thunderbirds

David
Old 04-12-2015, 01:49 PM
  #28  
icepilot
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Did you find a price for the T-33 from Blackhorse?
Old 04-12-2015, 03:57 PM
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The thunderbird scheme is no out yet they have another scheme that has the price. I think it was between 400-500euros
Old 04-12-2015, 09:29 PM
  #30  
Henke Torphammar
 
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Originally Posted by icepilot View Post
Did you find a price for the T-33 from Blackhorse?

Too small... http://modellhobby.de/BLACK-HORSE-Sk...&c=8997&p=8997
Old 04-13-2015, 04:43 AM
  #31  
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Selling right now

preceptor jet from phoenix models
jtm 90mm edf viper jet usarcjet
coming sebart mini avanti
check http://www.vogelsang-aeroscale.com if have the big budget.

Go and see forums at electric jet at rcgroups simce as here is fuel jets the other site is where all the electric guys hang.

Check also the buy and sell here and clasifieds at other site. Constantly selling jhh build jets which are for your turbine. Recently saw some f86.

cheers

juan
Old 04-13-2015, 04:48 AM
  #32  
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Living in Norway any Europe manufacturer is the way to go.

Sebart
savex l39 was build for this turbine.
There are several german manufactures buy a rc jet magazine and has a lot of vendors.

juan
Old 04-13-2015, 09:13 AM
  #33  
invertmast
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What would be the desired size for a wren44 size jet... 50" span, 60" long?

reason i ask, im finishing the CAD design on a sportjet that is loosely based on a popular speed jet and have been debating in sizing it for a 90mm or 100-120mm EDF. Pulling double duty for smaller turbines is prefered as well.
Old 04-13-2015, 08:19 PM
  #34  
Henke Torphammar
 
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Originally Posted by invertmast View Post
What would be the desired size for a wren44 size jet... 50" span, 60" long?

reason i ask, im finishing the CAD design on a sportjet that is loosely based on a popular speed jet and have been debating in sizing it for a 90mm or 100-120mm EDF. Pulling double duty for smaller turbines is prefered as well.
If a 105mm fan fits the Wren/K45 will. 90mm too tight(heavy) and 120mm too large. I'm aware of several 90mm with Wren44, but I think they are way too heavy, I'm also aware of Icepilots large Viperjet... but too large for fun I guess. Remember it's still a quite heavy engine needing to be fitted close to CG and not that powerful.
Old 04-13-2015, 11:54 PM
  #35  
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Originally Posted by invertmast View Post
What would be the desired size for a wren44 size jet... 50" span, 60" long?

reason i ask, im finishing the CAD design on a sportjet that is loosely based on a popular speed jet and have been debating in sizing it for a 90mm or 100-120mm EDF. Pulling double duty for smaller turbines is prefered as well.
Thomas

The main thing is to make sure that the plane will be light and the installation as simple as possible. Not easy to make as good a plane as the semi scale Savex L39. With a minimal installation it could weight dry complete with engine ready to fly under 9 lbs and fly the pants off most at the field. The old AMD Hawk surprisingly was a good flyer with a 44 and horrid with a 54. I would opt for about 1 litre of fuel. Best to use a pleated paper filter and save the weight of a UAT. In the UK no need for brakes and Springair air up spring down retracts with wire legs are light with a single action electronic valve. The exhaust pipe lightest weight solution is a Wren single wall pipe. Don't bother with gear doors and internal ducting, you can use the interior of the fuselage as a duct if you avoid too many formers.

The Wren 44 and the Kingtech 45 are both 4.5 Kg thrust.

If you can keep the weight complete ready to fly at 9 lbs that would be a good target.

John
Old 04-14-2015, 02:18 AM
  #36  
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John,
thmnks for the info. I was contemplating having the turbine mounted in the far rear to eliminate the need of a tailpipe, or a very short one (18-20"). Im not sure yet if i will do built up wings/H. Stabs or composite, maybe both. The solid model is done and will likely utilize a single access hatch along the top of the fuse that is around 20-26" long.
Old 04-14-2015, 04:06 AM
  #37  
Henke Torphammar
 
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Originally Posted by invertmast View Post
John,
thmnks for the info. I was contemplating having the turbine mounted in the far rear to eliminate the need of a tailpipe, or a very short one (18-20"). Im not sure yet if i will do built up wings/H. Stabs or composite, maybe both. The solid model is done and will likely utilize a single access hatch along the top of the fuse that is around 20-26" long.
Keep the pipe or go for pantera/F4 design. Engine badly needs to be as close to CG as possible! it make a HUGE diffrence in AUW. Every millimeter counts! (and/or a long nose.)
Old 04-14-2015, 07:51 AM
  #38  
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Sounds good. What wingspan/length do you guys think? Weight i dont see being to big a problem
Old 04-14-2015, 05:46 PM
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I built an 83% Turbinator. I started with a Limey Bob laser kit. It uses E-Flite retracts, HK electric brakes, standard digital servos and an old Ram 500.

Its flies great and was easy on the budget. It wasn't a hard build but it took a little work.

The Wren 44 would fly it well. It came out at about 15 pounds. I think you could save a few pounds by using wire landing gear and lengthening the nose a few inches to reduce the ballast. It uses large batteries and ballast to get the CG correct. If I built another, I would probably also use flat tail surfaces like the Reaction to same more weight and simplify the build.

At 12-13 pounds it would be awesome!

Scott
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Old 04-14-2015, 11:19 PM
  #40  
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Thomas

I would go with your initial thoughts, but agree with Henke that the engine is best at CG point. The one thing to avoid is a plane designed by committee. You will recall the FEJ Liberty which is no longer made! As you are trying to make a fast sport jet I would try and get it at 1:1 thrust weight and keep the wing loading as low as you can. You also could look at the BVM Electra and consider why it has not been a hit when converted to '44 or P60 power. Those who did the conversions a while ago predicted they would be popular, but I haven't seen one for some years. Also I do not recall them as being very fast.

John
Old 04-15-2015, 02:25 AM
  #41  
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Originally Posted by Jgwright View Post
Thomas

I would go with your initial thoughts, but agree with Henke that the engine is best at CG point. The one thing to avoid is a plane designed by committee. You will recall the FEJ Liberty which is no longer made! As you are trying to make a fast sport jet I would try and get it at 1:1 thrust weight and keep the wing loading as low as you can. You also could look at the BVM Electra and consider why it has not been a hit when converted to '44 or P60 power. Those who did the conversions a while ago predicted they would be popular, but I haven't seen one for some years. Also I do not recall them as being very fast.

John

John,
i would like to make it decently fast, but still have great low speed handling for those with shorter fields, aerobatic qualities are high in the list as well.
The design is mainly finished, i just have to finalize the airfoils and begin working in structures then i'll start looking into doing plugs and such.

Thomas
Old 04-15-2015, 10:10 PM
  #42  
Henke Torphammar
 
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Maybe a delta sportsjet? Like the squall or something like that. Sort of if a Futura would mate a Mirage 2000 :-)

Old 04-15-2015, 11:42 PM
  #43  
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Thomas

I shall be very interested to see it.

John
Old 04-16-2015, 11:28 AM
  #44  
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Wow! the Squall.. that's a throwback.
Old 04-16-2015, 01:50 PM
  #45  
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While the squall was a cool and unique looking airplane, i really didnt like the way it flew, so i couldnt bring myself to do a larger one of it. That said, the model i emmulated mine from is very nice and everyone i know who knows the original would love to have one, so i think this will be a hit at a smaller price and size.
Old 04-16-2015, 07:12 PM
  #46  
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Looking forward to seeing your design.
Old 04-17-2015, 12:51 PM
  #47  
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Originally Posted by Scott Todd View Post
I built an 83% Turbinator. I started with a Limey Bob laser kit. It uses E-Flite retracts, HK electric brakes, standard digital servos and an old Ram 500.
<snip>

Scott
Hi Scott, your Turbinator looks splendid! How are you getting on with the HK electric brakes? I have a couple of sets, and dismantled one to see how it worked. Pretty darn crude with a very short bushed bearing surface that looked ready to wear out within a couple of take-offs and landings. It seemed to me that they might be OK for a 5lb EDF model, but my Wren 44-powered Hawk I bought one pair for weighs 14lb, and I'm not confident the axles and bearings will take the strain for long.

Gordon
Old 05-13-2015, 03:34 PM
  #48  
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Time to get some input from you guys and give a quick little update on my design.

the 3D Solid model is done and will be going out for CNC'ing of the fuselage plug soon. Vertical fin will be integrated with the fuse and the canopy hatch will bemolded separately.

size- 62" length, 53" span, 530 sq.in of wing area
9 sq.in of exhaust exit area, 12.78sq.in of inlet area

I'm hoping to run one airframe for 90-120mm edf's and small turbines. I'm not going to release any photo's or cad renderings yet,but rest assured, this thing is awesome looking.

So,here's what i'm wondering.

Would you guys want built up, foam core or all composite? It utilizes full flyingstabs and the linkage will likely be all internal.
Retracts- what do you guys use weight category wise? i'm planning to utilize off the shelf units.
Gear doors, yay or nay?
flaps- yay or nay?

Thanks,
Thomas
Old 05-13-2015, 04:44 PM
  #49  
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Sorry I'm late responding Gordon...

The e brakes have been doing well. You need to take them apart every 10 flights or so and make sure there is no sand or dirt in them. It just takes a few minutes and I make it part of my post flight so When I put it away, its ready for next time. My 15lb model is doing fine with them. I had some issues with the Eflite retracts but sorted it out. I had too many extensions and splits and the voltage drop was causing them to freak out. I hard wired everything except the wing connections and they have been working good since.

Thomas, my 83% 15lb Turbinator flies really well. I think if it was a few pounds lighter, it would be a lot nicer and easier on things like gear and brakes. Its not built heavy, it just needs lots of ballast to balance. I hate to see full flying stabs. They induce more load on system and I have found them to be flimsy and a failure point. Just ground handling or bumping into them can induce large loads where a fixed stab could easily absorb them. Just my opinion....Foam cores are alright. If done right, it can simplify the build a bit. Gear doors look cool and may give a few MPH's but otherwise are a pain. A nose gear door can produce more speed but the main doors don't do much for us. Definitely flaps Jets are slippery enough as it is....
Old 05-13-2015, 06:06 PM
  #50  
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Thomas,

Flaps- yes
Gear doors-no
flying stab? Seems like unnecessary complication for a sport jet but it is your design.
I would go foam core wings. Makes iterations much easier if you need to modify. You have to get it right the first time tooling up for composite.

Look ok forward to seeing what you come up with. I really think there is going to be a market for this size plane. The new K45 is really going to be attractive to folks wanting to fly smaller jets for convenience and also people getting in to jets for the first time..

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