grumania

I would like to inform the EDF comunity about progress on the F 100 project.
It has always been my wish to make a conversion of our F 100 to EDF. Unfortunately I never had the time to get away from other important work to be done but now as we have enlarged GRUMANIA and also have an EDF specialist in the team, it was time to get my hands on it. There were several problems to deal with - most of all the comments of so called experts who always mentioned the scale inlet of the Sabre to make me believe that the EDF version will never work.
To take this before - thats all bullsh..
For having a starting point, I chose a low cost setup, just to get an impression of what is possible.The guideline was a simple setup with no retracts, scale cockpit, wing stations or so.
The duct that I designed had to make room for a retract that is later installed ( by the way, this duct is also a much better solution for the turbine guys who now have a full ducting system together with the Wren 44 ).
The chosen fan was the WEMOTEC MIDI fan, a very small and light Kontronik speed controller ( Beat 50-8-30) and a 7s 3800 Lipo battery.
Several tests on the bench have been made.
Fan without model, without lip, with inlet lip, attached to duct without model, the same inside the fuselage, followed by some tests with the fan installed behind the duct, with and without a rear duct. As expected the version with an open mounted fan gave the best results. Surprisingly we managed to get the rated thrust of the spread sheets in the WEMOTEC catalog - with some modifications on the model.
These are in detail:
1. The F 100 has a lot of "natural openings" which almost double the inlet area of the original nose inlet. There are machine gun openings, link ejection openings ( a lot !), emergency ram air turbine opening and many more.
2. The nose gear door, consisting of the smaller forward one - we left that away.The rest of the door can be hinged to create a "blow in door" like on Panthers and Cougars used ( spring operated doors, that open themselfes if engine needs more air)
3. The duct has a large opening above the nose gear - same size as gear door.
4. The duct was mounted 100 mm behind the end of the duct - sitting in the tail of the Sabre
All these modifications gave a perfect result regarding thrust, scale looks and practical construction issues.
We used a 250 mm rear duct, manufactured by WEMOTEC. The measured thrust with the duct was 1700 gramms ! Thats not bad at all, considering that the fan will produce only 1800 gramms in an open configuration WITHOUT The rear duct that is significantly tapered down to 85 % !
These first tests have been very encouraging and finally we could vectorise the formers and produce a first batch of ducts and formers.The first prototype will be flown soon with this setup soon.
Parallel, we are doing tests with a "high end " setup. People who know me are expecting a full scale Sabre with all that bells and whistles, with scale retracts and with a take of from gras- and that s what I was expecting from the F 100 right from the start. The next setup is an Aeronaut fan, a power motor driven by an 8S 5000 mAh battery and a TURNIGY 100 amp speed controller.The fan is place much more forward and the batteries can be serviced through the open canopy instead of the gear opening on the WEMOTEC Version. Total weight of the model with retracts and radio is 4000 gramms - the expected thrust will be in the 3700 gramm range -sounds promising
I`ll keep you updated about progress.
Ilja
GRUMANIA JETS

MaHo

Hi Ilja,
how much is the weight ready to fly with this setup!?
regards Martin

grumania

Hello Martin,
the motor for the TF 2000NG setup is the ARC 36-75-1. This engine provides brute power but is a bit heavier than the motor in the WEMOTEC version.The weight is 294 grams. In addition to that we will have a slight increase in speed controller weight, as I chose the Turnigy Sentilon 100A 5-12S BESC, which is again a bit heavier than others ( the reason for this controller is simply the extreme good price ! ).
Taking this in acount will result in an overall increase of 200 gramms but the copper cables are much shorten as the fan is much more forward. Another thing that I did not mention is that we put a model on the scale that was a B quality kit with very heavy parts, i.e. standard kits will be lighter - at least 200 grams.
That means that the weight - ready to go- will be the same - 4000- 4200 grams with a thrust of about 3700 gram.

Ilja

grumania

Hello Martin,
the motor for the TF 2000NG setup is the ARC 36-75-1. This engine provides brute power but is a bit heavier than the motor in the WEMOTEC version.The weight is 294 grams. In addition to that we will have a slight increase in speed controller weight, as I chose the Turnigy Sentilon 100A 5-12S BESC, which is again a bit heavier than others ( the reason for this controller is simply the extreme good price ! ).
Taking this in acount will result in an overall increase of 200 gramms but the copper cables are much shorten as the fan is much more forward. Another thing that I did not mention is that we put a model on the scale that was a B quality kit with very heavy parts, i.e. standard kits will be lighter - at least 200 grams.
That means that the weight - ready to go- will be the same - 4000- 4200 grams with a thrust of about 3700 gram.

Ilja

jcterrettaz

My Feedback: (1)

Well done, I always follows you work Ilja you are very talented[8D] . Keep us posted with price and options. It's definitively a nice Jet. But why 90 mm fan ? A Stumax(110 mm) fan will add some realisme with a real Jet sound..
J-C

grumania

Thanks for the kind words !
I thought about different fan options from the very beginning.The Stumax is of course in my considerations. For "simplicity" , I chose the 90 mm version, as I am not an EDF expert. The 90 mm version has some other advantages against the Stumax , more about that later.

Ilja

grumania

OK, lets start with the progress of last weeks work.
We made the new formers and ducts. A first trial fit of all the components showed that the prototype formers have been perfect and no changes are needed for serial production.The Photo shows this first "stick together" which was done in just two minutes.
The basic idea behind the former layout was to get the duct strengthened by means of a keel which is interlocking with the formers.This means that the internal structure is responsible for the outer skin strength and vice versa.Once glued to the fuselage, the whole assembly is some kind of sandwich.
This allows me to keep the weights of the single components as light as possible.

Ilja

grumania

Next step:
Glueing the formers to the keels.I used 5 minute epoxy to get a quick result. The blind nuts for the nose gear are also in position already, the formers are prepared for the retract mounting, I chose a flat mount system ( older kits had a different former layout with different retract fixing)

Ilja

grumania

Step two:
Sliding the duct inside the former/keel group and fixing it with epoxy.
The area behind the last former ( right side) is where a turbine is fixed if the MW 44 turbine is used. -YES, the turbine is mounted through the main gear wheel well as before with the old kits.


Ilja

grumania

Step 3.
Trial fitting the assembly in the fuselage - very tight fit.

grumania

Step 4:
Remebering the cackling duct of the first tests, I decided to strengthen the duct .I did it the same way as on the prototype ducting with the addition of honey comb pieces on top of the duct as this will be my desired location for the batteries.
By the way, my batteries arrived and for those gram fanatics- they weigh 550 gramms each ( two 4s packs).
I also installed the new motor that arrived and glued the Aeronaut fan as per instructions.

grumania

Step 5:
Cutting out the extra opening between former 1&2. This is the area where the nose gear retracts ( NO- it does not retract inside the duct !)
The cut out pieces are not thrown away! Lets safe the envirenment - these act as rails for the later made battery tray.#





Ilja

grumania

Step 6:
The fan
Where do I position it ? The first tests showed that a position about 100 mm behind the duct is perfect regarding thrust issues. As I chose a "high end"- setup that is much heavier ( motor ,speed controller behind CG !), I had to change the original position of the fan more forward to get make the desired battery position possible. A quick assembly of the model with all components together inside the fuselage showed me the perfect location for the fan.
What a surprise - Now I am exactly at the location, where the forward fuselage is mounted to the rear part ! Perfect - the motor stays in the front while the rear fuselage part contains only servos for rudder and elevator, very practicle.

grumania

Step 7
Shown in previous post, I could cut off the rear section of the duct.The duct assembly could have been much easier if I knew this before...........
OK, now I cut off the rear part and make some little mods to the rear former to accept the Aeronaut fan. Now its just a few steps to my ready build model.
As you might have seen on previous pics, theres always this silver Hun in the back ground.That is my show model that has been made for exhibitions and fairs, it is an "empty" fuselage without any formers at all.
I decided to use this model to underline the basic idea behind the former/duct- layout.
On the other hand, it is something different if you build a model and paint it then or the other way around !
To see the ready painted model every day in the workshop, is something that speeds up building the internals............
Picture shows the rear duct and eyelid style - scale nozzle. I`m starting to get nervous and can`t wait to get my hands on the flying Hun.

Ilja

grumania

One disadvantage of the ready built "Show-Hun" is its fixed rudder - at that time there was no scale rudder available but meanwhile I have a propper rudder that fits to the rest of the detailing.

Ilja

grumania

One disadvantage of the ready built "Show-Hun" is its fixed rudder - at that time there was no scale rudder available but meanwhile I have a propper rudder that fits to the rest of the detailing.

Ilja

jcterrettaz

My Feedback: (1)

Ilja , you are the best You should publish an article about this F100 EDF in RC Jet International . Let me know when this electric version is ready for shipping to Canada.Merci.
J-C

Greg Covey

Hi Ilja,

I agree with J-C, your builds are very impressive! Thanks for posting photos and showing your progress.

Regards.

cyclops2

When are you starting the build thread on the..............FULL SCALE .........as in the thread title ?


Rich

grumania

Sorry for the misunderstanding. Its just a bad translation from German into English.The German expression of "full scale" ( thats very common here when talking about scale models ) just means that the model is completely scale in any aspect, showing surface details down to the tiniest detail and featuring other scale aspects such as scale wing airfoil, scale cockpit and............. The little Sabre provides this



Ilja

mark_d

Great looking example Ilja, I envy your skills. The weathering is perfect.
The american expression for a finely detailed model is precision scale btw. As big as the giant scale models are getting now i too thought you were making a 1:1 scale version of the Super Sabre. The title definitely got my attention!

grumania

Just found an old picture from the beginning of the redesign, made this summer. I thought it might be of interest. Here you see the basic layout of the duct, very similar to the shape on the FULL SIZE -Hun ( haha, this time right , Mark !).
Of interest is the position of the retracted nose gear.As on the full size, its very tight here ! The leg features the distinctive "kink back" when it is out ( 90 deg. movement )

Ilja

grumania

Step 8

The wing plug ins
As I didn`t had much time today,I only made the plug ins.This was very quickly done and not a big thing.Just cut two brass tubes and glued it to the main former.

grumania

The whole duct/formers group is still not glued to the fuselage and will not be . After epoxy has set, I took out the assembly and trial fitted the wings again.Now with the wings attached to the inner structure, the basic idea behind this layout comes apparent.
The fuselage is not much more than a shell which has nothing to do with the stability of the model.It would even be possible to fly now without any fuselage around it.
There`s one little detail that might be of interest. The two holes in former N0. 2 are for the tanks ( turbine version ) a third tank is on top giving a total of one litre - just enough for the little Wren 44.

Ilja

grumania

Step 9

The whole assembly again slipped into the main fuselage and another trial fit showed that everything is as it should be, perfect fit of wings to the fuselage side wall ( the wings root rib contour is not straight as the fuselage has a concave shape )
The inside of the fuselage has been sanded for the next step - glueing in the double former to hold the fuselage tail - thats something for tomorrow.....................
Of interest in this shot are the various "holes" in the forward fuselage.These are scale openings that are not only nice details on a scale model - in this case, the sum of all these openings doubles the inlet area ! Sometimes scale details help to solve problems......


Ilja