TD 09 Ducted Fan

aungmyatoo wrote:The small acrylic tube in the middle of your photo. Any idea what that is for, that also missing in mine. If really necessary I have to search that tube size as well. thank you

After some studying, I found out!!
This polycarbonate tube has the diameter of the "spider" that sits on the tank end and is 35 mm or 1 3/8" long. It fits over the engine mount and is used when mounting a .15 engine. The tube has to be cut to shape and fits around the engine mount with a part that goes below the engine. This can be seen in figure 3. The explanation is in the last paragraphe of the previous page above figure 1.

I bought this kit about 25 years ago in a model shop here in Germany.
At that time I wanted to build a Horten IX and was looking for a second kit. But I never saw one again and today I would do the project electrically.
At the moment I have no idea what to do with it. I know what 1/2A Nut would do with it   , but .09 TD / Conquest .15 is not my class.
I hope the question is not dubious here in the forum, I think I paid around 80 bugs back then. How would the value be today?

Hello Emanuel,

I have a RK720, the next larger Version of the RK709. I did know Bob Kress personally. He invented the ducted Fan with a model engine in the late 70's. When I remember correct, he hold the patent for it. He worked for Grumman Aerospace and was responsible for the variable sweep wing in the F14. In the early 90's, his ducted Fans where superior in thrust, but, a pain for the average modeller to build. He designed a range of very interesting model aircraft with unique features. EG a P-39, engine in the middle and two belt-drives to the outer Propeller. I also have a F15 designed by him, this could be flown either with a Cox 09 in the front, or, with a RK709. Amazingly, as the F-15 was a rival design to the F-14. I build it with the RK-720 and a K&B .21 It had a thrust to weight ratio of about 1,5 to 1, which was sensational at this time. I think, the RK-709 is a collectors item. Too complicated to build and meanwhile there are many many electric fans around.

regards,

Roland

Thank's for the background info.

When I got my ducted fan, it came as parts in a box without the polystyreen. I'd like to know the shape of the curved hole that houses the turbine.



According to Kress' articles in RCM issues of 1977, this profile should be ideal for the air inlet when constructing the ducted fan nacelle. Can someone draw the curved line on a piece of paper and make a scan?

Thanks.

Hope you mean thouse holes...

Haven't got a scanner

Emanuel,

Thanks for the effort but it's in fact the curved or rounded shape of the polystyreen insert - the white bit - that I'm after

Thanks Emanuel, That's what I needed. I assume that are 5mm squares.

In the mean time I searched for the ducted fan articles by Kress on RC Library:

Part 1......RMC 10/1977 https://rclibrary.co.uk/title_details.asp?ID=2216
Part 2......RMC 11/1977 https://rclibrary.co.uk/title_details.asp?ID=2223
Part 3......RCM 4/1978 https://rclibrary.co.uk/title_details.asp?ID=2331
Part 4......RCM 5/1978 https://rclibrary.co.uk/title_details.asp?ID=2337

I also had hydro-dynamics when I was studying.
So I know that the curve would have to be turned by 90 degrees, the slight curvature of the curve must be inside the pipe so that the air detachment is smaller. Here is my engineering table book with examples, unfortunately in German.

I started the build of my ducted fan. I hope to bring this to a good end because I have the impression that many difficulties will arise during construction.

According to the instructions, the first thing to do is to assemble the fuel tank. 2 fuel nipples need to be opened with a 1,5mm drill. They're the connections to the fill and vent tubes. In the big central hole comes a plastic and rubber plug with a 2" suction line and clunk weight. The plug has a washer and nut that compresses and expands the rubber inside the tank hole to make the assembly fuel tight.

First, I was puzzled reading the instructions but soon found out they had to be read from right to left.

emanuel wrote:

I didn't know - and it's something that Kress doesn't mention- that putting a pylon in the middle of the intake reduces significantly the losses. I suppose that is what can be seen in the air intake of a MIG15.



That plane is after all a Focke-Wulf Huckebein. Give to Cesar what belongs to Cesar!

After assembly, the silicon tube for the clunk weight was too stiff. In the instructions, Kress suggests to use Aerotrend #1001. This happens to be the standard 049 silicon tube. I replaced the tube and now the clunk works perfectly.




The rubber seal of the tank plug needs a little soap for lubrication before mounting. I then fixed the 3 silicon tubes. The upper tube is for venting. the middle one is the feed to the engine and the bottom one is for filling the tank.

At this stage I have a nice plastic squid!

The vent tube is smaller than the filler tube and this has a reason. Both tubes pass trough a wing profile shaped tube and te passage is very narrow.



The kit I have is not made for receiving a TeeDee 09. The back of the fan is countersunk for making it possible to mount a longer engine. The fans for a 09 are just flat. The  engine mount is for an Enya 11 CX. I haven't got a TeeDee 09 or an Enya 11 CX but what I have is a Conquest. For this engine, the engine bearers need to be bevelled a bit on the inside to give room for the crankcase.

getback wrote:Are you going to put this in a Mig 15 or something else ? The Conquest .15 should get the job done , I  don't have or ever ran one But have seen then fly/run  !

I don't know what model to pt that in yet; early jet plane, airboat, Super Cyclops?? and I still have to test run that Conquest!

Wow, adding a Conquest. This will rock.

Yes, a Conquest engine should really wind that thing up compared to a TD .09 engine.

Just be careful, the early conrods (cast ones) on the Conquest engines are fragile and cannot take too high rpms.

Today, I made what Kress calls the clear plastic centerbody. It's a piece of polycarbonate tube that has to be cut to size and that goes around the motor mount and extends below the engine. One could call it a sump guard.







The inside diameter of the tube is just too small to slide over the round part of the motor mount. Parts were cut out with a Dremel and adjusted with a file. the centerbody needs to be screwed onto the motor mount with  4 #2x 3/8 PHSMS !?  That means  pan head sheet metal screws. It takes some time to translate these numbered screws and drills.      






Screws:




Drills