SpiderJets

I also started with the idea : 'I'll make 2 small mods...."

And then... you meet with a first guy who flew it and changed something you did not really think of... and who also has a friend who flew his... and crashed...

And then you say : "Ok, I'll make 2 small mods and one single big one..."

And there you go. We almost redesigned the whole thing in the process !

But the good news is : I am close. I should fly again next weekend, weather permitting ! [>:]


Nicolas.

tomcat0818

My Feedback: (3)

i just got back let you all know that we did 8run with this he was diong roll flips and and just to let you all know we took all safey be for
the frist run thay had that all set up but any way we check it over be for all run it did good in all runs we are going to do more mods
to it over all it stayed in tack did not come a part so not bad but it can use some more mods and now 100% at we seen it frist hand
we now know what we have to do ..and the guys that did this thay been flying for over 15 years and we do have pic and video of it
and as soon as i get back on disk i will post it

bahamadude

The least they could have done maybe is lower the price, add that work must be done and start over with a version III.


Now they have a video on the site !! Oh my


Talk about testicular fortitude (grapefruit size ) [:@][:@][:@]

RCISFUN

My Feedback: (44)

OK I have put together a PDF conversion document for the Formost 150, it is still a rough draft but I figured I would share.

This conversion is different from Nicolas's conversion as it utilizes a longer CF spar.

You can download the file from the following link
This file contains all of the drawings in PDF format so you can print them out and use them as templates, the drawings are scaled for 8 1/2" x 11 paper

http://www.filecrunch.com/file/~5yukdj

Instructor

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Hi RCISFUN,

I sent you a pm on the PDF file you supplied. Let me know what you think.....

Larry

tomcat0818

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think for more info ..we did do some test run was all go just to see how the new kits hold up it did good but i think it need some more mods ..we did the test with his plane
but he have the money to do with .i dont i just mine i got two of them and i dont have
a lot of money so i like to do it right the frist time so that i came in here to get all the info i can i know thay say it junk but with some time i know this can be a good flying plane and i been get a lot of help and plus seeing one fly with 2 small mods done to
it was cool anyway thanks larry for all that info it help a lot and thanks to for the info
thay gave me

RCISFUN

My Feedback: (44)

Hello Larry and to all other who have PM'd me, I appreciate all of the positive comments that I have received.

MattyC-130

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I will be ordering one this week. Planned Mods:
- Replace 4 aluminum wing tubes with 2 carbon fiber tubes that extend halve the length of the wing panels and all the way through the fuselage.
- Remove sheeting on bottom of panels from spar back double sheer web between ribs with sheer web running verticaly.
- Double all the ribs, from the spar aft, overlaping oval lightning holes.
- Add tubes for the carbon fiber wing tubes to fit into.
- Remove all covering from wing panels and horizontal stab. glass with 3/4 oz. glass.
- Strengthen main landing gear blocks inside the wing with fiberglass and carbon fiber tape.
- Fill booms with 2 part filler as described in this thread.
- 2 DS821s in the horizontal stab
- New Canopy, I hate the looks of the present one.
- Split flaps between the fuselage and booms.
- Sand the booms and fuselage paint grey and orange in Tiger Meet Scheem like the Tiger Meet F-16
- Plan on using JJ-1800 for this project, yet to buy from Gabe.
Matty

RCISFUN

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You may want to reconsider the filler of the vertical fin, if you download my PDF instructions you will find a 1:1 drawing of the former I used for the fin, also all of the ribs are included

MattyC-130

My Feedback: (5)

RCISFUN,
Thanks a million for the PDF file, has alot of great info I will be using on my Formost.
You are the kind of member and poster to this forum that RCUniverse is designed for. Sharing and offering techniques/info for your fellow RCer. Rather than some of the premodonas out there that offer no useful information and would rather get on their high horse and slam and downgrade aircraft and engines that don't cost $10,000.
Thanks again
Matty

RCISFUN

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Thanks for the complements

jets2

Hi, here is a link to my formost video with smoke pump http://uk.youtube.com/watch?v=CAX9gfs-QZw

MattyC-130

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Very impressive high speed snap rolls. What mods did you do to the wing and booms? What engine are you using?
Thanks,
Matty

i3dm

My Feedback: (51)

I agree - looks great ! which mods ?

jets2

Hi Matty look at Post #: 336

jets2

Formost has a jetcat p60, carbon fiber spar in wings , drilled small holes in bottom of booms and wings ,put $5.00 Grate stuff spray can foam inside wings and booms ,did not fill them full! wings and booms are very strong

bahamadude

any pics of the inside with foam ?

SpiderJets

Just for everyone's better understanding of the dangers of the unmodified kit, I have removed the top balsa skin completely from my new set of wings.

I am posting here some photos of the internal structure of the wings. This is very fragile and totally unsafe. The wing tubes are barely supported, the wing ribs (balsa 2mm thickness) very fragile, and the original balsa wing spar of 1/10" balsa (2,5mm) with the grain in the wrong direction must be considered as a non-existent part.
The oval shaped openings only make it a lot worse.

Only modification done so far on these photos is the full plywood wing spar (W1...W7), which is in the Digitech conversion set and which adds a lot of strength.

In the meantime, I have continued the wing reinforcement on mine. We go for the 10G barrier, minimum. [8D]

i3dm

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Spiderjets, so is the Digitech conversion suitable enough as far as wing strength goes ?

RCISFUN

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Here is some photos of my wing

RCISFUN

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Ok...tonight I decided it was time to put all of the wing mods that I did to the test, I'm not sure if this was the best set-up but this is what I did.

I supported the outer wing panels with 3/16" plywood on two saw horses. I padded the plywood with old towels, then I placed the Formost inverted on the boards, then padded the bottom of the wing with more towels. I then placed a sand bag that was marked 70 Lbs (32 Kg) on the wing, when I weighed it on the scale it was 80 Lbs (36Kg).

You can see in the photos that the wing did bend slightly under load, I am assuming that this was a 5 G test as i am hoping this will weigh 16 Lbs when completed. I am planning on using a RAM 500 for power so there is no way I would ever pull more than 5 G during normal flights.

For this test all I did was slide the wings and the booms onto the CF spar, no bolts were used and I used the stock small alum. anti rotation tube in the back of the wing.

SpiderJets

Finally some test which is impressive ! Congrats Rich, I wish you the best with your maiden flights. PS. Try to do something about the torsion forces on the wing also, these break the four-five mid wing ribs... I also agree with your idea that it is not really necessary to replace the rear spars with one long spar, they basically only serve as anti-rotation and for spreading the landing gear shocks.

Gents, please try the same G-test with your jets [8D].


I am not doing much on my Formost right now, but the idea will be to do a similar test as Rich, but with myself standing on top of the wing shoulders of my FoldMost between the two tailbooms.
I am sure mine would be eventually able to take a JetCat P-160, although such idea is insane and misleading and not meant to encourage others for trying the same stupidity.... with less building&reinforcing care perhaps. Just want to proove that you can do something useful with a crappy original design. I do not want to open the discussion either, about the pro's and con's of the extra work done and what particular aspect drives each modeler in this hobby. All I can say is that I look forward to finish this project very soon and enjoy it with full confidence for a very long time to come.


Nicolas.

SpiderJets

There are two main forces destructing the original wing: the forces on the wing spar and the torsion force. Together, they break the internal structure.
The G-forces break the wing spar and the torsion forces break the wing ribs.

Solving the G-force problem.
---------------------------------------
The main structural problem with the Formost is that the G-forces on the wing tube are not properly translated to the wing spar. To achieve this, you must create a rock solid structural bridge between the wing tube and the wing spar. Reinforcing the wing spar with the panels W1-W7 makes the wing spar very strong, but the link is still weak. Such creates breaking forces on the third and fourth wing rib in particular.

What I did is creating a triangle plywood "box" structure, with connects the wing tube with the wing spar, by adding also panels BEHIND the wing tube, all the way to the wing spar.
On the top and bottom will be glued 2mm plywood triangles (covering the triangle above W7-W6-W5), so a complete plywood box is made. Such "box" is almost unbreakable.

On mine, I have also glued the wing panels W1-W7 on the back side of the whole spar, so it is doubled now. (Doubling it is not absolutely necessary.)

I am not ready yet, but the photo in attachment shows the idea well.

Solving the torsion force problem.
-----------------------------------------
After that, I have to close the main oval openings of the wing ribs with thin balsa rectangles in the other grain direction, apply a new balsa wing skin, and then glass the entire wing.
Glassing the wing will help the most against torsion, but the wing ribs must be able to stand the internal push and pull forces ( "imploding" / "exploding" ) .

-Sorry for my bad english.-



Once finished, I am sure this structure will be able to carry my own weight.

Nicolas.

richbran

There are a few contributors (US born... heh, heh,) in this thread that can learn a lot from You, Nicolas!

Keep up Your efforts, all of the readers here like it, whether You think it is "sane" or not that one has to put so much redesign in an ARF..... basically building it again from scratch, good to see many still out there who can appreciate this skill.

RCISFUN

My Feedback: (44)

Nicolas,
Great job on your wing so far, I can't wait to see your load test.
It would be good to see others doing this test also.

I agree it is not absolutely necessary; however... you can't beat twice the strength for a little of work, effectively you have created an I beam spar
I would recommend that the manufacturer should adopt the I beam construction.

Boxing in the short spar section on your wing is perfect, I did basically the same thing only on sections 3, 4 & 5 as my spar is now in deeper.


For clarity I will identify the ribs from the root out as 1, 2,3...

The plywood ribs I added to ribs 3, 4 and 5 should solve the rib opening issue, and Rib 1 (root) looks like it is made from sufficient material, so this leaves Rib 2 on mine untouched, from your photo this rib looks like swiss cheese.
Also I did not do anything with ribs 6, 7 and 8 as I feel that the loading on the outer portion of the panel was sufficiently lower; however here again the manufacturer should consider making all of the holes much smaller in all of the ribs, use virgin wood that is not spliced together and good glue for the joints.

p.s. I agree with richbran...you could be an English teacher