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IAR-99 SOIM (hawk) for 90mm EDF

FoamyDM

Building Fool-Flying Noob
#1
Inspiration:
90mm EDF, 80A ESC and 3000 6S battery with no plane.
Looked around, the diamond looks appealing. but I thought about what else... and decided to design the Romanian Air Force IAR-9 SOIM (hawk)

iar_99c_soim-68782.jpg IAR-99_8.jpg

Plane Specs:
from the Wiki Page:
General characteristics
  • Crew: 2
  • Length: 11.01 m (36 ft 1 in)
  • Wingspan: 9.85 m (32 ft 4 in)
  • Height: 3.9 m (12 ft 10 in)
  • Wing area: 18.71 m2 (201.4 sq ft)
  • Aspect ratio: 5.2
  • Airfoil: NACA 641A-214 (modified)
  • Empty weight: 3,200 kg (7,055 lb) equipped
  • Max takeoff weight: 4,400 kg (9,700 lb) Trainer; 5,560 kg (12,260 lb) Ground attack
  • Fuel capacity: Internal:1,370 l (360 US gal; 300 imp gal); External:up to 450 l (120 US gal; 99 imp gal) (in 225 l (59 US gal; 49 imp gal) drop tanks)
  • Powerplant: 1 × Turbomecanica/Rolls-Royce Viper Mk632-41M turbojet, 17.79 kN (4,000 lbf) thrust
Performance
  • Maximum speed: 865 km/h (537 mph; 467 kn) trainer, clean
  • Maximum speed: Mach 0.76
  • Range: 1,100 km (684 mi; 594 nmi) Trainer with internal fuel; Ground attack with internal fuel 967 km (601 mi; 522 nmi)
  • Combat range: 345 km (214 mi; 186 nmi) hi-lo-hi at 5,280 kg (11,640 lb)all-up weight
  • Service ceiling: 12,900 m (42,300 ft)
  • g limits: +7 / -3.6
  • Rate of climb: 35 m/s (6,900 ft/min) at Sea level
  • Wing loading: 235.2 kg/m2 (48.2 lb/sq ft) Trainer; 297.2 kg/m2 (60.9 lb/sq ft) Ground attack
  • Thrust/weight: 247.5 kg/kN (2.42 lb/lbfst) Trainer;312.7 kg/kN (3.06 lb/lbfst) Ground attack
Armament

Build Specs:
TBD

Plans:
Alpha Set 90mm EDF IAR-99
1 of 4, 2 of 4, 3 of 4, 4 of 4
canopy.jpg

Come build with me...
 

Attachments

FoamyDM

Building Fool-Flying Noob
#2
I managed to cut this out and start building.
I feel I made some Good Headway. Here are the progress photos.
I had to adjust the rear fuslage sides and top to adjust for the angle of the bottom. I trimmed 3/8" (2 thicknesses.)

IMG_20181012_003025912.jpg rolled over to see if it lines up. wing cut and ready? IMG_20181012_012014866.jpg
Nope, I need more Cowbell, well higher spar at least; IMG_20181012_084648273.jpg
Now I've glued the fuse up and tested to fit the EDF. As designed I will be cutting groves for the lip. so far working great. the nose seems like it will come together nicely. (held off for now.)
IMG_20181012_084657158.jpg
Got the wing folded over, and wanted to look at a photo before I add the tiny dihedral that is present. I didn't want to add too much. IMG_20181012_085921676.jpg
Lay-up mock-up, yup. the vision is coming together. IMG_20181012_092027928.jpg
So FAR, i am pleased. I'm worried about the size of the wing vs. weight/size of the plane... now to work out the details. :devilish:

Out you devil! :)
 

FoamyDM

Building Fool-Flying Noob
#4
I'm been excited and anxious about the canopy. I want to do a foam one, for now, then use this as template for overhead or reflective mylar.
I designed one up and tried it out. I also put together the undercarriage part. What's that called?
Here's some pics, I'm very happy how they turned out. See for yourself.
IMG_20181025_012003166.jpg IMG_20181025_012020347.jpg IMG_20181025_011953062.jpg
This is my first real attempt at 100% pre-designed curvy stuff. It did need a tiny of trimming to fit flat. 😀
 

DamoRC

Well-known member
Mentor
#5
Looks really great! 90mm EDF on 6S? That's a lot of power.

You said you were a little worried about the weight versus the wing size - what do you think your final all up weight will be?
 

FoamyDM

Building Fool-Flying Noob
#6
Lets see....
600g 6S 4.2Ah Battery + 310g motor + 82g esc + 6g receiver + 4 MG servos - 50g + 4 sheets of FB and glue - 340g = ~1.4 KG? with 2.6 to 2.8g+ of thrust...
I know the ratios are fine, It's a small thin wingfoil. I'm used to Flite test style, which makes me worry about how much lift I'm going to get on those wings.
 

buzzbomb

I know nothing!
#7
Just chiming in to say I think it is looking really cool! I've said it on this forum before, and I'll say it again: I can't wait to see that thing in air!
 

FoamyDM

Building Fool-Flying Noob
#8
I have glued the canopy down to a base (note to self:add canopy base to drawing set) and the rest of the turtle deck. I also cut the wing profile out of the bottom...
1554442076328401336829.jpg 1554442108518140469761.jpg
and for the tail assembly to the turtledeck and maintain a motor access hatch.
It's looking promising to me.
IMG_20190405_012215392.jpg
I want to add retracts. Let me fly this first.
I have to spend some quality time with the air intakes and an iron to the wing edges.

Stiffen here, mould there. Pretty soon you have an airplane.

I plan to do the canopy like the viggen battery hatch. And latch it with a magnet or two
 
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