HobbyKing BF-109 Pylon Racer - RC Groups
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May 26, 2012, 07:13 AM
The wheels touch down FIRST??
BJ64's Avatar

HobbyKing BF-109 Pylon Racer

Hi guys.

Not sure if this thread belongs under here - is it a Warbird? Or is it a 'high performance plane'?

It kinda sits somewhere in between, but I've put it under the Warbird's section.

There's not a lot of info on the 'Net about these lil planes, and only relatively a few comments on the HK website under the product.

So maybe we can use this as a Forum to discuss the various aspects of this plane - like the build quality and the building of it itself.

Motor/ESC/LiPo combinations that owners of this rather unique are using.

Plus anything else you'd like to discuss about the HobbyKing BF 109 Pylon Racer...

Last edited by Jim T. Graham; Jun 01, 2012 at 11:10 AM.
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May 26, 2012, 07:59 AM
The wheels touch down FIRST??
BJ64's Avatar
Ok... I'll start the ball rolling...

I found the fibreglass fuze to be of excellent quality for a plane in this price range. It maybe a little thin aft of the cockpit area, but it still seems to be rigid enough. I guess the acid test will be how the tail-end behaves at speed - depending on what sort of powerplant you go for.

It's not a scale fuze - far from it. Kinda squashed a bit in the longitudinal axis. It actually has a rather mean look to it with the blacked-out canopy and black stripe that runs along the top back to the tailfin, and is perhaps is a tad 'cartoonish'. Sort of a hot-rod.

The German Cross decal is interesting - not the full cross, and actually recessed into the glass. As is the number ‘1’, and a couple of other little blips on the starboard side. The yellow around the cowling is very neatly finished on mine, and there's a couple of exaggerated details and guns slots around the nose area. And there plenty of places on the aircraft to put your own fav Schmitty decals

I’ve read that the rear stab slot has a positive incidence to it. To my untrained eye, it does look like the LE of the stab will be a touch high. Hopefully those with more knowledge in this area will comment as the Forum progresses. I may hold off gluing the stab in until this gets sorted – I’d rather file it out a bit now rather than trying to fix it once it’s all together.

The wing themselves look well made – balsa sheeted foam core. The grey covering with the yellow tips looks good, though the more finicky may find fault with a few of the overlaps etc. The wings have little plywood ‘bibs’ on them for where they slot into the fuze – this looks a bit fragile to me, again depending on how hard you are going to push the aircraft. The rear of the wing fixes to the fuze via a pair of screws and captive nuts.

Ailerons are actuated via a single servo with a full double-sided control horn – servo sits in the centre of the wing. You’d have to do some surgery if you wanted to run independent ailerons.

Now – a few of the not-so-good things so far:


No instructions – at all. Well, not with my kit, anyways.

Ian from HobbyKing Support kindly supplied the following link to a PDF format of the ‘manual’ : http://www.hobbyking.com/hobbyking/s...65X7478X19.pdf

It’s a bit sparse, but there’s enough there to assemble the plane and set the recommended factory CG.


The bolt holes for the rear of wing mount points aren’t pre-drilled. No biggie, as it’s pretty simple to do, but it would have been nice to have them already there so that everything matches up – which it doesn’t. Strangely enough, the mount bracket has the holes predrilled.

Wing Mount Captive Screws

The wing mount captive screws weren’t ‘captive’ on mine at all. As soon as I touched them, they fell out. Plus, they’re the wrong size! The supplied wing bolts are 4mm, while the nuts are 2.5-3mm. And just to add insult to injury, they don’t line up with the wing holes in the fuze if you set the retainer bracket to where they show you on the wing in the pic in the manual.

A bit dodgey, IMHO – but nothing that can’t be fixed.

Wing Join

I took a fair bit of care getting the wing joiner in the right place and joining the wings to set the correct amount of dihedral, but I either didn't do it right, or the fuze is slightly out. There's a bot more of gap between the wing curve and the fuze curve on the starboard side compared to port. Not sure whether this will affect anything, or that there's all the much I can do about it - short of trying to cut into the join until it's loose enough to adjust for a better fit, then re-gluing it. It's more or less cosmetic at this stage, but it's there if you look.

Control Horns, Rods, Servo Bays etc.

The control horns and clevises are made from that real brittle plastic. You may want to replace these with your favourite Dubro’s or whatever – particularly the clevises.

The aileron servo bay is a bit iffy. The base (where the servo makes contact with the bottom of the wing ply) needed a bit of a Dremel clean-up so that the servo would sit square. The servo retaining plate doesn’t have the best of fits. I had to fiddle around with screws, CA etc. until I managed to fashion a half-decent servo mount.

Motor Bay

The entry to the motor bay is restricted by the pentagonal hole cut into the ply that is part of the pre-installed Elevator/Rudder servo cradle. The LiPo is supposed to Velcro up into that area somehow, though I haven’t got that far yet (and there's no Velcro supplied either).

The access to the motor bay will govern the size of motor you can run - a 36-55 inrunner won't fit in there without some Dremel work on the oddly shaped ply hole (a 36-55 is probably going to be waaay too heavy for this plane, but I had one lying around so I thought I'd see if I could get it in there. Nup.

Nose Plate

The nose plate is shown as pre-drilled on the HK product page and in the manual so that it can accept several motor types - mine just has a single hole for the axle to come through. I don't know whether this is a good thing or bad thing. It does mean I can drill holes into a fresh 'firewall', but I'm not sure how much of a PITA this might turn out to be.

More later…
Last edited by BJ64; Jun 08, 2012 at 09:45 PM.
Jun 02, 2012, 08:53 PM
The wheels touch down FIRST??
BJ64's Avatar
Having a bit of trouble sourcing the recommended "1400-1600kv 28mm inrunner".

Does such a thing even exist...?

Jun 03, 2012, 12:23 PM
Registered User
Manu Simon's Avatar
A friend of mine bought it. He was able to put a 35mm outrunner without any problems: this one actually:

Unfortunatly he lost it during maiden due to radio problems, lost all control and the plane crashed nose first.
Jun 03, 2012, 10:41 PM
The wheels touch down FIRST??
BJ64's Avatar
Thanks for the info, Manu.

Sorry to hear about the lost plane.

I figured I was going to need to go for something bigger than a "28mm 1400-1600kv inrunner" (which I don't think even exist - when they're that narrow in diameter, they're usually 3000kv+).

How did your friend get it past the servo/LiPo cradle bulkead? I tried to poke a 35mm diam motor through there, and it looks like there's a bit of Dremel work to get it through.

The Turnigy 3648 at 1450kv should give the 109 a decent amount of poke. Apart from the crash, how did your friends plane fly? Nice and quick? And do you know what prop he was using - and where the CG was set and any other mods needed to get it flying?

Sorry for all the questions, but there's not a lot of info about these things around yet (hence the reason I started this thread).

I think they're a fabulous looking machine - can't wait to see mine in the air

Jun 04, 2012, 10:26 PM
Registered User
Fearse's Avatar
I also have one of these planes and like you have not decided what motor im going to use. i have a D37-L40 1250kv exceed rocket motor that i was thinking of using but i will have to finish assembling the plane to see if its weight will be ok. Ive had this plane for some time now and kind of hit a snag when it came to assembling the servo tray for the elevator and rudder. Its almost like I didnt get all my parts( actually I know I didnt ). I need to get off my rear and finish it.
Jun 16, 2012, 05:54 AM
Registered User
Thanks for the ref. to the manual doc. I have just about completed my build and have used the following;
ESC H'King 50 Amp
Battery Turnigy 2.65 30-40c 4s
Prop 7x4.5 H/K Pt#7940
Bench test showed the following:
32.95 Amps
!4.85 volts
I had to grind out the fuselage former so that the motor would fit , then I had to grind some more so that the battery could also slide through.
Still have to install elevator and rudder servos. Have used a 63mm plastic spinner with alloy backplate(sprayed matt black).
Jun 16, 2012, 08:39 AM
Registered User
TripleW's Avatar
Do we get a pic of the bird in question?
Jun 17, 2012, 07:10 AM
The wheels touch down FIRST??
BJ64's Avatar
Originally Posted by TripleW
Do we get a pic of the bird in question?
Haven't seen any set-ups yet.

The Bird is fairly new, and hence this thread - to see if we can get a few ideas of what people are running.

I've managed to Dremel out the servo bay 'firewall' to shoe-horn a Turnigy 3648 1450kV into the motor bay. I'm not sure how this wall all work out, as the motor is a tad on the large/heavy side.

Once I've got it mounted, I can work backwards to see how a 40-60A ESC and LiPo to suit will work as far as CoG goes.

If it ends up too heavy on that set-up, I may have to try something a tad smaller like the 3536 1200kV W.A.D. is going to run.

For now, here's a couple of pics of the airframe itself from the HK website.

Pretty sleek, and cuts a fairly wicked profile, IMHO.

If it flys half as good as it looks, it may be a wee gem

Jun 17, 2012, 08:33 AM
Looking4Grass in AZ
Afraidtoregister's Avatar
Pretty much the coolest project airframe I've ever seen. Can't wait to see setups.
Jun 18, 2012, 05:12 AM
Registered User
Finally got servos installed.For the ailerons I have used GWS
Micro 2BBMG,probably overkill but they shouldn't let me down.The rudder has a Hextronic HXT900 and for the dual elevators I have used Corona DS-939MG Digital.I wasn't too keen on using the 9gram servos as suggested in the assembly instructions.This plane is meant to be flown flat out at all times and that is what I intend to do!This plane is definitly not a bind and fly proposition: plenty of scope for improvement and fixing kit problems, but I relish the task of remedying these problems . You end up with a plane that is free of problems and a personal pride in making a great plane out of a cheap kit that most R/C fliers couldn't be bothered with. God, I hope the plane flys!
Jun 18, 2012, 08:13 AM
The wheels touch down FIRST??
BJ64's Avatar
Really looking forward to hearing how you get on with your 109 Racer, W.A.D.

I'll hopefully get back into continuing the build on mine later this week

I've gone for HXT-900 on the (single) aileron and rudder, and an MG-90 for the Ele on mine. I'd like to do separate aileron servo's, but I can't be bothered cutting the the wing bay just now.

As I mentioned before, it will be interesting to see how it all pans-out with a Turningy 3648 1450 up the front. I like the idea of running a bigger prop/lower kV v's than the 'screaming meanie' sound of a high kV/small prop.

Those ole warbirds had that 'deep prop' sound - so if I can find a way to emulate the super-charger whine over the top of more resonant larger prop, it might just sound good. Maybe some kind of reed or 'flute' shoved somewhere near the lower nose intake duct (cut open for airflow)?

Dunno - just some ideas I'm playing around with.

First and fore-most, of course, is to get the thing up there to see if it's a fighter or a fizzer.

The basic airframe suggests that it should fly quite well - though I'm seriously thinking of re-inforcing that LE plywood bib that tucks into the slot up front. I can just see the fuze continuing upward while the whole wing assy decides to part company with the aircraft during a high-G pull-up

Should be a few challenges coming up as we find the ideal combo for this rather unusual yet promising looking plane...

Aug 04, 2012, 05:14 AM
The wheels touch down FIRST??
BJ64's Avatar
Looks like I'm 'back on the air'.

Well, in some threads at least...


Hmmm... maybe not?
Aug 07, 2012, 12:52 AM
Registered User
Well the plane is a goer! Maiden was O.K.; ground handling quite a handfull but plenty of power and airborn very promptly.Ailerons are quite sensitive,will reduce throws to calm them down. After getting the plane trimmed,went to full throttle which resulted in loud vibration noise, reduced power and noise ceased. Landed and discovered that the ply/fiberglass engine mount was starting to break up underfull power. Have reinforced with 3 layers of 6 oz glass and epoxy; this has cured the problem. looking forward to future flights.
Aug 07, 2012, 09:07 AM
The wheels touch down FIRST??
BJ64's Avatar
So kewl to hear that, WAD.

Mine is coming close to completion - though I opted for the Turnigy 3648 1450kV motor.

Reading that you had firewall problems running your 3536 1200kV, you've got me a bit worried now - since the 3648 I've put in mine is bigger, heavier, and pulls a heap more power.

How did you get in there to do your reinforcing? Can't even get my pinkies in there to touch the motor, let alone try to do any surgery to the nose/firewall area. Or did you do it from the outside?


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