turnnburn

My Feedback: (49)

I need a set of wing mounting tubes/spars for a Hoptspot. I need the dimensions, O.D., wall thickness, type material and where I can buy said material. I would also like to get a Clear canopy. I now know that the O.D. is 20 mm which equals 25/32" if Im not mistaken. I dont know the I.D. or wall thickness yet.

cmjets

Hello:

You can get it here:

http://www.rcuniverse.com/forum/m_11333192/tm.htm

Regards from Spain.
Carlos Márquez
_________________________________
http://cmjets.blogspot.com.es/

turnnburn

My Feedback: (49)

There must be somebody or somebody who knows somebody that might have an extra set of the 20mm hardened alluminum wing joiner tubes for a Hot Spot ? Even a crashed (bent ) tube might help me. If nothing else I will try to find the tubing locally but I would sure like to know the wallthicknees or I.D. or both ?

Randy M.

My Feedback: (38)

The hotspot uses a single tube going all the way through the fuse into the wings. should be easy to find

turnnburn

My Feedback: (49)

do you know what the wall thickness or inside diameter is ?

jason

My Feedback: (1)

The ally tubes also had dowel rods about 5 inches long pressed to the wing-fin-fuse shear points.

Jason

Randy M.

My Feedback: (38)

I don't remember the thickness. I do remember graupner supplied a wood dowel plug that was inserted into the tube. It was about 6-8 inches long and was positioned centered on the wing joint. Just get a quality tube, aluminum or carbon fiber. You should be fine. I had an 18-20 lb engine on mine and flew it as aggressive as I wanted. Never a problem.
You may try troybuilt or modelbaul and see what they can do

turnnburn

My Feedback: (49)

Yes, but I intend to go to 25 lbs eventually.

Randy M.

My Feedback: (38)

.035 chromoly should work

turnnburn

My Feedback: (49)

centered on what wing joint ? The joint where the wing mates up to the fuselage/vertical fins. I presume. if that is the case I would need two wooden dowls, one for each side. I assume they go inside the aluminum spar, one on each side, centered with approx 3 inches sticking into the wing panel and 3 inches inside the fues wing root where the wings mate up at.

turnnburn

My Feedback: (49)

.035 is the wall thickness ?

Randy M.

My Feedback: (38)

wall is about 1mm. that's probably why they went with the dowel insert. can't hurt to go a little thicker.

jason

My Feedback: (1)

I have two Hotspot tubes here. One is 19.90mm with a .9mm wall and the other is 19.85mm with a .78mm wall.

Jason

Art ARRO

My Feedback: (5)

turnnburn,
I just measured the alumimum spar wall thickness and it is .040". This is on my Graupner Hot Spot, and note that there were, and are,several suppliers of this kit over time. Grooved wooden dowelsare inserted into the spar to reinforce the wing-to-fuselage joint. The grooves are shallow, about 1/16" wide and deep, and probably only serve to retain any adhesive to hold their position within the spar. My Hot Spot is pre-maiden and has JRDS-168 servos for the rudders-installed with shortest HD servo arms, longest Robart control horns and 4-40 linkage with Sullivan clevises. JR8411 servos, 1eaper wing panel, are my elevon controls. Ensure that the fins are really stiff and mine are reinforced with CF strips running spanwise and glassed with 2 oz cloth. The fins are also retained to the fuselage by 10-32 bolts,fore and aft, threaded into fuselage-mounted blind nuts.
Be sure to include about 1/4" uptrim in the elevons to providesome airfoil reflex before the maiden. There areseveral Hot Spot pilots here and you should ask their advice on anything that you're unsure of. Good luckwith this classicjet and happy landings-no bouncing!

Art ARRO

SJN

Strongal 20mm, 1mm

http://www.flugmodellbau-shop.eu/pro...x-1000-mm.html

turnnburn

My Feedback: (49)

Thanks for the info, you hit on several ares where I have questions. You obviously also saw my JR 168 servo post. This airplane came equipped with JR 8411, one per side for elevon. I had concluded that this servo should be up to the task, I was concerned as I see most guy run two servos per side but mix them as elevons rather than one for ailerons and one for elevators. But I think these servos will do the job kust fine with a proper amount of safety margin. Whoever built this glued the fins in place plus there are two I think # 8 or # 10 sized screws also. I have no idea what kit this was built from. There does not appear to be any reflex built into the wing that I can detect. I am assuimg it would be pretty obvious even to the naked eye ?

Sadly the hinging of my elevons and rudders is a little suspect. The left wing elevon has a a pretty good bow in it. The builder failed to notice this and at both the root and the tip the elevon centerline is not on the wing centerline. Im not yet sure why but the left elevon can only move about half as much in either direction as the right elevon can. The right elevon has more than enough travel but the left one Im araid does not have enough. I expect I will be cutting the hinges, removing them and then do my best to get the bow out and then rehinge properly. the hinge line gap is marginally acceptable on the elevons. Since I will close that gap after redoing the left elevon I will need to rehinge the right side as well so they both have little or no gap and an even gap on both sides. Both rudders have an excessive gap that needs to be resolved. One rudder is a bit warped or bowed also. So...........looks like I will be rehinging both rudders also.

Art ARRO

My Feedback: (5)

One JR 8411 servo per elevon is fine, guys have installed 2 for redundancy-still rigged as elevons- not separate ailerons and elevators.
Glued fins to the fuselageare fine but ensure that they are stiff-in torsion, at the tips. That's where the flutter begins. I used Kraft Hayes polypropylene hinges , 3 ea, for the rudders, epoxied and pinned with toothpicks. For the elevons I chose 4 ea. per surface Klett large/HD hinges, epoxied and pinned in place. I'd fix the bowed surfaces and seal the gaps with Scotch clear vinyl tape, one side is enough usually the bottom. Re-hinging is recommended as the Hot Spot is a pretty high performance jet.
Also, think about securing the canopy to its frame with small (#1 or 2) sheet metal screws as there are a lot of requests for spare canopies that depart the model inflight.

Art ARRO

turnnburn

My Feedback: (49)

I finally made my the first two flights on my hotspot that I purchased unflown a few months ago. It has an old AMT air start mercury that I am starting with a leaf blower since I don't have a scuba tank. First two flights went quite well, cg,control throws and trim were all quite good. I did notice a slight tendancy to hunt a little as far as level pitch trim is concerned. I would get it to where I thought it was trimmed for level flight on one pass then on the next pass it seemed to want to descend a bit. I need to check to see if the elevator centering is good or if maybe its not quite centering the same each time. I might also move the cg forward a bit even thou it is not at the recommended aft limit yet. All in all it was a very satisfying first day out. did make one slightly hairy go around on the first landing, otherwise it was a piece of cake.

erbroens

A backward or forward CG in the Hottie doesn´t wouldn´t help in this problem, A forward CG makes landings harder "running out of elevator" , and a back cg makes the airplane "touchy" or "unstable" at landing approach. At speed there is hardly a difference between this two settings.

As you said it is more likely that there is a problem in the centering of the servos, and/or slop in the linkage or even slop in the wing alignment pins.


Anyway great to hear you had a great day with it.