Formost 150 Build/Conversion - RC Groups
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Jul 13, 2017, 10:56 PM
Calm before the storm
Flyboy81's Avatar
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Formost 150 Build/Conversion


I have recently agreed to build a Formost 150 for a friend of mine I met here on R/C groups. I am in the preliminary stages of the build. All the other stuff I had planned to build is on hold until I can get this one finished. I hope to achieve all the goals set for this build. It will Include the following:

1) Create a cheater hole for the EDF on the underside of the airplane.
2) Install electric retracts and reinforce the landing gear housing areas.
3) Possibly reinforce the tail booms on this one as I have read about people folding theirs on high speed runs.
4) Retrofit a fan housing assembly and create a battery tray/RX area.
5) Hopefully make the canopy fit a little bit better that what was provided.
6) Not screw this up.
7) Decals and maybe some touch up on the paint.

Also if anyone has built one of these before wants to chime in please do. If you just want to follow this build chime in. I should be posting weekly updates on how it is going. I hope to have this done in about a month or two. I am a slow builder and can only dedicate about 2-3 hours per night and sometime less with family and work.
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Jul 18, 2017, 01:46 PM
wannabe Jet guy
CRCJA's Avatar
Have you looked at the other threads? Here is a link to one you might find interesting.
https://www.rcgroups.com/forums/show...EDF-conversion

I would abandon the "Cheater Hole in the bottom" and just do like the others and make one in the hatch. You don't want the user (I assume Gary) sucking up debris into the fan and or mesh getting clogged because it's under the plane. I bought inlets for mine back in the day (left one in the picture below) but I don't know / think you can still get them. They are Venture intakes sold by the same company.

Ralph
Jul 18, 2017, 10:39 PM
Calm before the storm
Flyboy81's Avatar
Thanks for the response. I haven't cut the cheater hole yet but I do have a cheater hole template made. I have screening for the cheater. Yes building this one for Gary. I am really just doing what he asked me to do. I thought ducting would be a better option as well. I appreciate the comments and I will consider them. I don't like the idea of a cheater either but also trying to do what Gary has asked me to do. I will look into cost as well...if they are 100 bucks or something crazy then no.
Jul 19, 2017, 11:18 AM
wannabe Jet guy
CRCJA's Avatar
Just to be clear, I am not saying to abandon the cheater hole all together, I am saying make it on the hatch like others have done.

1. You don't weaken any structure or have to add re-enforcements.

2. Already a proven Design.

3. No small rocks to knick the fan blades (or like 99% less of a possibility of it happening).

Either way, good luck on your modifications, and by all means, what ever works for you and or Gary. I still have my foremost with the EDF too.

Ralph

Quote:
Originally Posted by Flyboy81
Thanks for the response. I haven't cut the cheater hole yet but I do have a cheater hole template made. I have screening for the cheater. Yes building this one for Gary. I am really just doing what he asked me to do. I thought ducting would be a better option as well. I appreciate the comments and I will consider them. I don't like the idea of a cheater either but also trying to do what Gary has asked me to do. I will look into cost as well...if they are 100 bucks or something crazy then no.
Jul 19, 2017, 04:02 PM
John Green
I had a couple of these a few years ago. There were a couple of others in the club flying the Formost and I always found the sag ( upflexing of wing tips) of the plane alarming. One members wing looked like it flexed up 4 or 5 inches in tight turns. ( It may not have been that much, but watching you would have sworn the wing would break). We have a tight field so if you get any speed up you are going to pull high G turns to keep in bounds.
I solved the problem in my Formosts by putting a carbon fiber tube clear across the airframe and extending into the existing wing tubes. The carbon tube is 20mm if I remember correctly. You can turn one of the provided wing tubes into a drill by cutting teeth in one end and use that to drill the top corner of the wheel wells to clear the spar all the way across. The tires will still fit with room to spare. Makes the wing really solid for only a little time and effort. The tube however runs about $90. I had a P-60 in mine and it would haul... but I still had those tight turns to deal with, and the spar fixed that.

John

PS Lost both of mine to tip stalls on final when I slowed down just a little too much. It wants you to keep the speed up until you cross the thresh hold.
Jul 19, 2017, 11:04 PM
Calm before the storm
Flyboy81's Avatar
Thanks CRCJA and Plumber John for the comments. I am building it with a carbon tube that will span to both wings and through the fuselage. I haven't been feeling well this evening after a long day in the hot sun so no working on it this evening. I will see if I can work around or maybe even come up with a design of my own tubing. I am afraid that I will lay it up too thick and it would be heavy. I have 1/2oz fiberglass on hand but would mock it up with pvc glued and smoothed out to fit, greased and layed on till it hardens then peel it off. It was an idea but this would be the first time attempting it. As for the elongated sides I would have to get those measured and cut out with cardboard or paper stock first.
More updates this weekend possibly. My son is in town so I will be spending some time with him until he has to go back to his moms. Family first. Modeling second.
Jul 20, 2017, 01:53 PM
EDF all the way!
bruff's Avatar
Here are some pictures of my Formost 150. I ran the carbon spar all the way across which cured the flexing issues. No duct work just aux openings in the upper hatch. In process of installing a new fan, DS-86 AXi 120mm .
Bob
Jul 20, 2017, 07:23 PM
Calm before the storm
Flyboy81's Avatar
A picture is worth a thousand words. Nice set up there. Why not a cheater on the bottom then? Just tossing the question around here. I don't see any disadvantages to having a cheater on the bottom really. Other than maybe a bit of loss of lift? With a 76 inch WS that shouldn't be an issue at all. Plus if I can make it look as good as it flies then I think I have something. Also about the tip stalling issue. Any way to prevent that? possibly wing fences?
Jul 20, 2017, 08:00 PM
EDF all the way!
bruff's Avatar
Sucks up all the dirt and junk off the runway. will shorten the fan rotor life big time.

Bob
Jul 20, 2017, 10:46 PM
Calm before the storm
Flyboy81's Avatar
Ok so a screen wouldn't avoid that? I am on the fence really here. Gary wants a jet that aesthetically looks good (which I agree with) but also performs well (which I agree with as well) so with both things going into this I would prefer to do ducting. Alas, haven't found anyone avail to produce any ducting for this jet at a semi reasonable price.
Possibly a loose weaved piece of foam like for carbs on nitro engines.
Anyways I am still contemplating a work around this problem.
Obviously I would have to make the cheater even larger than anticipated for the screen and foam insert.
Jul 21, 2017, 12:01 AM
EDF all the way!
bruff's Avatar
Screen does a great job of blocking air. Really slows down it's flow. Open is best.
Bob
Last edited by bruff; Jul 21, 2017 at 12:33 PM.
Jul 21, 2017, 12:33 AM
Registered User
Zenoaheli's Avatar
i think you would need half scoops on each side to draw in enough air for the fan to produce enough thrust required for reasonable performance
Jul 21, 2017, 07:54 PM
Registered User
Quote:
Originally Posted by Flyboy81
I would prefer to do ducting. Alas, haven't found anyone avail to produce any ducting for this jet at a semi reasonable price.
.
Call Vertigo they still have the EDF inlets for the Venture.

http://www.airshowrc.com

Richard
Jul 22, 2017, 01:16 PM
Calm before the storm
Flyboy81's Avatar
I have Emailed Airshow RC hopefully get a response from them. Ducting isn't offered separately on the website so we will see what they say.
Jul 22, 2017, 05:38 PM
Registered User
Quote:
Originally Posted by Flyboy81
I have Emailed Airshow RC hopefully get a response from them. Ducting isn't offered separately on the website so we will see what they say.
Airshow will get back to you. I contacted them about a two weeks ago looking for spare parts for my Venture Jet. They told me the only parts they still had in stock was the EDF intake ducts and canopy for the Venture Jet. As already mentioned earlier, the Venture ductwork can be installed in the Fourmost 150.

Richard


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