Thorp Air Command - T18.net

Heat is the issue with the side vent of the engine cooling. Your primary goal here is to insulate. As for sound, get a good headset.

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Bob Highley
N711SH
SN 835
KLAL

Ah, I don't notice much heat on the panels even being bare metal.

I don't have issues with sound but we aren't able to bring our dogs for a ride in the thorp due to the sound. If I pull my headset away from an ear to listen for engine noises it's painful loud even in cruise. If the insulation did anything for this I might be inclined to try it. I know the lack of exhaust muffler is the main reason but I'm not adding that boat anchor of weight to the thorp.

What is considered loud is a matter of perception. I don’t really consider my Thorp loud because I could carry on a conversation without an intercom and/or ANR. That may be too loud for dogs though and is quieter than I am use to.

Mine is insulated all the way around in one way or another to the spar. The sides are done to the seat backs.

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

Mine isn't close to that sound level. That's about like my Piper though. In my thorp I don't think I could handle more than 30 seconds without a headset. It causes physical pain in my ears. And I was on a 105mm field artillery line for my first 4 years in the army.

I had the same Maule tailwheel on my airplane. I believe either Ken Brock or Tom Hunter highly recommended replacing the single fork with a dual fork tailwheel as there had been incidents of the single fork breaking. I changed to the ACS dual fork on the standard Thorp flat spring. I can not determine from your tailwheel photo, but I also highly recommend compression springs rather than extension springs on the control horn.

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[b]Terry[/b]

Heat on the sides hasn't been much of a problem with my Thorp. You might enjoy the extra room without the Styrofoam. Besides that, do you know how flammable that stuff is? I'm not fond of the bubble wrap stuff either, but for places like the firewall you might use fiberglass wool - it doesn't burn. McMaster-Carr has lots of "aircraft hardware" and here's some 1" lightweight, foil-faced, rigid fiberglass sheets you can cut with a knife:

https://www.mcmaster.com/#thermal-insulation/=1ajhhpl

Les Krumel,
Albuquerque

Hi All, I'll be removing most of the insulation prior to the conditional inspection. But I'm not sure how to get rid of the insulation on the firewall without taking out the tank - any ideas? BTW - I did a burn test on a piece of the foam insulation that I took out already and it burns pretty well, Les.

I'll look into the tailwheel after I do the taxi tests and report on how it feels. I believe I have the compression springs.

My conditional is being split into at least two sessions - 1) while the airplane is apart, and 2) when it's all buttoned up and ready to go. The first session is scheduled for Dec 30.

I'm torquing the engine mount bolts this weekend on Saturday. I have the O-290G with the rubber donut mounts with the steel spacer inside. When torquing these AN7 bolts, should I torque them to the standard AN7 value - or just "snug" them up to where the steel spacer inside is snug? How do you define "snug"?

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

I had everything out of mine to move my battery to the firewall. There is little to no room behind that tank although depending how strong the glue is held you could possibly use a long piece of aluminum sheeting (in a small width) and get it under the insulation at the bottom and work it up to the top to pry it from the firewall. Then once all the glue is broken you could just pull it out. That seems tedious but I think it would work. I think it would be extremely hard to get insulation stuck back on with the tank in place though. I have maybe 1" between the tank and the firewall which would make it hard to get an adhesive backed piece of insulation up inside there then properly seated. The biggest issue would be not being able to properly clean and prep the surface.

If all you are doing is removing then I would use the above technique and it should come off with some work.

I don't know the answer of the torque but both A&P at my field (one which has built and restored many experimental and pre-ww2 planes) says they always use the given torque settings based on the AN bolt size unless there is a published number in a manual (such for specific engine bolts). I would think that mount would be standard torque on what that AN7 should hold although hopefully someone else in here has the specifics on the engine mounts. I would 100% use a proper torque wrench though.

The rigid fiberglass board I mentioned is stiff, so you can just push it into place if you cut it to fit tight.

Hi Everyone, I hope you are all well and had a good winter. I basically took a 2.5 month break while it was very cold here, and I've now started working on N12055 again .

Last night I did a cowl fit check. After changing out the old, sagging rubber shock mounts last year, the new donuts lifted the engine back to where it used to be (about 3/16"). The prop hub is now centered in the cowl's prop spinner opening. And you can see where the generator pulley was rubbing on the inside of the cowl but isn't any more.

I've read that this type of cowl required people to remove the prop to remove the lower half just to change the oil, for example. If so, what are best remedies such as cutting in access doors, etc?

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

I don't remove my lower cowl to change the oil. I've got a quick drain. I feed a small hose up through the exhaust opening to the quick drain. Easy.
Cubes

thats what I do as well. I remove my lower cowl once a year at CI time. I am able to get it off and on without removing the prop, but it takes some time to do it.

Ryan - do you have the Ratray (sp) cowling like mine? If so, what is the procedure you've worked out to get it off and on?

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

I dont know which type cowl I have. But, to make my life easier, when I remove the lower cowling, I remove the gear leg fairings first which I have made to be undone with a few screws. I basically drop the back end down first then drop it out of place. Reverse goes for the installation. IT has to be done that way because the prop/spinner will get in the way otherwise. The only part about my lower cowl I dont like is that my carb heat system is part of my lower cowl, so I have to remember to undo the carb heat cable, and tubing.

I have a quick drain as well, but when I change my oil, I also inspect everything in the engine compartment, clean the plugs, check all the electrical, feed the squirrel and check for any leaks. Hence I remove the whole cowl. Takes less than 5 minutes when sober on mine though. I figger firewall forward is worth an inspection a cupla more times a year than the rest of the plane....I hope that doesn't come across as sanctimonious.....I'm the last person here who should be preaching.....

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)