H9 33% Pawnee Tug Conversion

[Xroadie]

Finished up the Pawnee today. It balances with the radio batteries in the cockpit. It just needs the spinner and pilot. I added an anti-glare panel and wing anti slip treads.

[Xroadie]

Just got verification.....10 inches at the root rib....not the leading edge.

[Xroadie]

I'm about to balance the Pawnee I'm working on. I have read a CG of 10 inches is good for aerotowing....is that 10 inches back from the leading edge of the wing or 10 inches back from the leading edge of the root rib? There's quit a difference

Pete

[Stevenson]

its gigantic plane build.

[kd4jaz]

I bought new springs from McMaster, took the gear apart to replace/upgrade the springs. The stock springs are made of stainless and appeared in good order. Put the OEM's back in place. I do think I'll build up the upper gear bearing supports, raise the top support just a little, this will give just a bit more ground clearance for the prop. I also replaced the 10-32 upper bearing bolts as they were slightly bent. Over 3 yrs of takeoffs and landings on those, so I can't complain too much. I picked up two 3/16" stainless steel pins from McMaster-Carr for the upper LG supports mounts. I'm going to build a bulkhead for those and install at a later date. I'll post pictures when I do.

[stevekremer]

Thanks Jim. I know that trick. I am making headway.

Steve K

[JimD]

Steve, here is a way to cut the holes accurately.

[lenb]

We didn't need to cut holes for the wires

.

[stevekremer]

No snow here, but cold. I am trying to fit the Pawnee cowl. I think I am going to have to cut holes in the sides to get the plugs and ignition caps to clear. and put holes further back to route the ignition wires thru. once cut, then remove plugs, install cowl, install plugs, put on ignition caps, sounds like a lot of holes. Any other suggestions before I start cutting?

Thanks

Steve K

[lenb]

That looks great Steve,
Cut the headers with a cutoff disc or hacksaw,
a tube cutter will crush them in slightly and may cause issues I've been told ?

[stevekremer]

OK Got the cannisters fit and mounted. Now to get the cowl to fit with them and get the headers hooked up
By the way, how do you recommend cutting the headers? Hack saw, cutting wheel, tubing cutter........

Steve K

[Xroadie]

Where did you get those strut fittings from?

http://www.mcmaster.com/#2448k41/=10nha73

[kd4jaz]

I ended up using the Red Wing Xion locks Andrew....I had a set of four that I bought for my KA6, but they weren't long enough, so I tried those. I could have soldered the bushing on a 440 bolt, like Tom said and mounted the McMaster Carr slide catches, but the Xion locks literally take seconds to mount in the fuselage and I already had four I am going to use the slide catches on the Carbon Cub.

I also upgraded the strut end clevis, to the ones that Len suggested...again from McMaster Carr. I got the size threaded for 4mm, a 25mm long 4mm threaded rod and a 4mm coupler nut that I found at a Menards store. The new clevis is only 16mm long...which is much shorter than what comes with the kit, necessitating lengthening the 4mm threaded rod on the end of the strut. I cut down the strut end rod to half the length of the coupler nut and added the 25mm long rod then added the 4mm nut supplied with the kit and the new clevis...I used Red Loctite on all. On the strut mounting plate on the side of the fuselage, I drilled out the hole to 1/8" for the new clevis and because the new clevis has a 1/8 wide jaw and the strut plate is only about 1/16" thick I added phenolic washers, that I had sitting around to the underside of the plate with JB Weld. I did that so the clevis would not rattle on the plate.

Here's a pic


Len in your photo there is a fan shaped ply bulkhead under the turtle deck, the model I'm working on just had a piece of foam there. I thought the ply was buried in the foam and I dug away the foam looking for it. Also who sells tow releases that are designed to mount on the back of a bulkhead like you used? The pilot I am building this model for supplied two releases, one from Iflytallies and one from Espirit....both are designed to mount to the front of a bulkhead.

Pete

Where did you get those strut fittings from?

[kd4jaz]

Hi Steve,

I found a photo sequence for doing the canister modification and thought I would post them for you or anyone who is interested.

Len

[ATTACH=CONFIG]n6136[/ATTACH] [ATTACH=CONFIG]n6137[/ATTACH] [ATTACH=CONFIG]n6138[/ATTACH] [ATTACH=CONFIG]n6139[/ATTACH] [ATTACH=CONFIG]n6140[/ATTACH] [ATTACH=CONFIG]n6141[/ATTACH] [ATTACH=CONFIG]n6142[/ATTACH] [ATTACH=CONFIG]n6145[/ATTACH][ATTACH=CONFIG]n6144[/ATTACH] [ATTACH=CONFIG]n6143[/ATTACH]

Very nice workmanship!

[kd4jaz]

This is not a new idea obviously.....but all our other threads about it are gone......for now!

I just started working on a commission to build a H9 33% Pawnee for aerotowing. The model will have a DA100, with the standard pitts mufflers. The customer also supplied a tow release mechanism for the tug. Is there anything that needs to be modified or upgraded on the Pawnee for aerotowing? I plan to go with as big a gas tank as possible...100 oz...if it will fit! What about the landing gear...do the springs need to be upgraded?

Thanks for any input!
Pete

I have a DLE 111cc in my pawnee turning a Falcon CF 27x10 wide blade and have towed 55 lb sailplanes with it. (towed the 55 lb before putting on the 27x10 CF) No problem towing a 6M Ventus that weighs 26 lbs to 1000' in about 1 minute. I've got over 250 tows, I did replace the bulkhead landing gear bolts with larger ones. The OEM bolts bent.

Marc